Search

The Fourier-Galerkin method is considered here for the solution of the unit cell problem that describes the homogenized properties of periodic materials in the scalar elliptic setting. The method is based on a Galerkin approximation with trigonometric polynomials and leads to linear systems suitable for iterative solvers. In [1], Zeman et al show the effectiveness of Conjugate gradients (CG) which is compared here with its block version (BCG). We show that the latter version outperforms the CG especially for anisotropic materials with non-symmetric distribution of material properties. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)

Photoluminescence measurements on 6$H$-SiC doped with nitrogen have been performed under hydrostatic pressure up to 50 kbar at low temperature $(T$=29$\ifmmode\pm\else\textpm\fi{}$2 K). The observed emission lines ${S}_{0}$, ${R}_{0}$, ${P}_{0}$, ${S}_{02},$ and ${R}_{02}$ are due to excitons with holes from the $A$ and $B$ valence bands bound to the neutral nitrogen donor. The energy shift of the ${P}_{0}$ line under hydrostatic pressure is used to determine the linear pressure coefficient of the indirect gap of 6$H$-SiC, which yields 0.20 eV/Mbar. The energy difference between the emission lines ${S}_{02}$ ${(R}_{02})$ and ${S}_{0}$ ${(R}_{0})$ of 5.15$\ifmmode\pm\else\textpm\fi{}$0.1 (5.08$\ifmmode\pm\else\textpm\fi{}$0.1) meV gives the splitting ${\ensuremath{\Delta}}_{\mathrm{AB}}$ of the topmost valence bands. We employ nonrelativistic band-structure calculations within the density-functional theory based on the local-density approximation in order to calculate the pressure coefficient of the indirect band gap of 6$H$-SiC (together with those of 4$H$, 2$H$, and 3$C$-SiC as well as those of diamond, Si, and Ge) and the crystal field splitting of the valence band. The latter, together with the experimental splitting ${\ensuremath{\Delta}}_{\mathrm{AB}}$ of the topmost valence bands A and B is used to estimate the spin-orbit splitting of 6$H$-SiC to be about 7.7 meV. The calculated pressure coefficient shows good agreement with the experimental value.

In 1994, Moulinec and Suquet introduced an efficient technique for the numerical resolution of the cell problem arising in homogenization of periodic media. The scheme is based on a fixed-point iterative solution to an integral equation of the Lippmann-Schwinger type, with action of its kernel efficiently evaluated by the Fast Fourier Transform techniques. The aim of this work is to demonstrate that the Moulinec-Suquet setting is actually equivalent to a Galerkin discretization of the cell problem, based on approximation spaces spanned by trigonometric polynomials and a suitable numerical integration scheme. For the latter framework and scalar elliptic setting, we prove convergence of the approximate solution to the weak solution, including a-priori estimates for the rate of convergence for sufficiently regular data and the effects of numerical integration. Moreover, we also show that the variational structure implies that the resulting non-symmetric system of linear equations can be solved by the conjugate gradient method. Apart from providing a theoretical support to Fast Fourier Transform-based methods for numerical homogenization, these findings significantly improve on the performance of the original solver and pave the way to similar developments for its many generalizations proposed in the literature., 22 pages, 1 figure

Analysis of material interfaces in composite materials is in the center of attention of many material engineers. The material interface influences significantly the overall behaviour of composite materials. While the perfect bond on material interface is modelled without larger difficulties, the imperfect bond between different components of composite materials still causes some obstacles. This contribution concentrates on application of the FETI method to description of the imperfect bond.

Photoluminescence experiments on 6H-SiC doped with nitrogen have been performed at low temperature (T = (29 ± 2) K) under hydrostatic pressure up to 5 GPa. The pressure coefficients of the S0, R0, P0, S02, and R02 emission lines related to the neutral nitrogen donor bound excitons were determined. The pressure coefficient of the indirect gap of 6H-Sic deduced from the P0 line turns out to be +2.0 meV/GPa. Nonrelativistic band structure calculations within the density-functional theory based on the local density approximation are used to calculate the pressure coefficients of the indirect band gaps of the 6H, 4H, and 3C SiC polytypes. The comparison with available experimental data shows good agreement with the theoretical results.

Luminescence and Raman scattering experiments have been performed on different types of porous silicon (PS) samples as a function of the hydrostatic pressure. These measurements allow to compare the response of the material in different structural phases and show that under moderate conditions of pressurization the strong PS luminescence is still observed though the sample has been transformed in a structural phase different from the diamond phase. They provide also upper bounds on the degree of the phase transformation which is discussed. In addition specific PS Raman features are observed for the first time on these transformed samples. It is concluded that the PS luminescence is not related to the diamond phase of silicon and that the emitting medium involves more likely surface related complexes of the material.

This paper presents a stochastic Wang tiling based technique to compress or reconstruct disordered microstructures on the basis of given spatial statistics. Unlike the existing approaches based on a single unit cell, it utilizes a finite set of tiles assembled by a stochastic tiling algorithm, thereby allowing to accurately reproduce long-range orientation orders in a computationally efficient manner. Although the basic features of the method are demonstrated for a two-dimensional particulate suspension, the present framework is fully extensible to generic multi-dimensional media., 4 pages, 6 figures, v2: minor changes as suggested by reviewers, v3: corrected two typos in the revised version

The paper reviews several topics associated with the homogenization of transport processed in historical masonry structures. Since these often experience an irregular or random pattern, we open the subject by summarizing essential steps in the formulation of a suitable computational model in the form of Statistically Equivalent Periodic Unit Cell (SEPUC). Accepting SEPUC as a reliable representative volume element is supported by application of the Fast Fourier Transform to both the SEPUC and large binary sample of real masonry in search for effective thermal conductivities limited here to a steady state heat conduction problem. Fully coupled non-stationary heat and moisture transport is addressed next in the framework of two-scale first-order homogenization approach with emphases on the application of boundary and initial conditions on the meso-scale., 19 pages, 13 figures, 2 tables

This paper presents a methodology and software tools for parametric design of complex architectural objects, called digital or algorithmic forms. In order to provide a flexible tool, the proposed design philosophy involves two open source utilities Donkey and MIDAS written in Grasshopper algorithm editor and C++, respectively, that are to be linked with a scripting-based architectural modellers Rhinoceros, IntelliCAD and the open source Finite Element solver OOFEM. The emphasis is put on the mechanical response in order to provide architects with a consistent learning framework and an insight into structural behaviour of designed objects. As demonstrated on three case studies, the proposed modular solution is capable of handling objects of considerable structural complexity, thereby accelerating the process of finding procedural design parameters from orders of weeks to days or hours., 22 pages, 15 figures, v2: Substantially revised after the first review

The focus of this paper is on the analysis of the Conjugate Gradient method applied to a non-symmetric system of linear equations, arising from a Fast Fourier Transform-based homogenization method due to Moulinec and Suquet [1]. Convergence of the method is proven by exploiting a certain projection operator reflecting physics of the underlying problem. These results are supported by a numerical example, demonstrating significant improvement of the Conjugate Gradient-based scheme over the original Moulinec-Suquet algorithm.

The physical characteristics of focused two-successive (tandem) shock waves (FTSW) in water and their biological effects are presented. FTSW were ­generated by underwater multichannel electrical discharges in a highly conductive saline solution using two porous ceramic-coated cylindrical electrodes of different diameter and surface area. The primary cylindrical pressure wave generated at each composite electrode was focused by a metallic parabolic reflector to a common focal point to form two strong shock waves with a variable time delay between the waves. The pressure field and interaction between the first and the second shock waves at the focus were investigated using schlieren photography and polyvinylidene fluoride (PVDF) shock gauge sensors. The largest interaction was obtained for a time delay of 8–15 μs between the waves, producing an amplitude of the negative pressure phase of the second shock wave down to −80 MPa and a large number of cavitations at the focus. The biological effects of FTSW were demonstrated in vitro on damage to B16 melanoma cells, in vivo on targeted lesions in the thigh muscles of rabbits and on the growth delay of sarcoma tumors in Lewis rats treated in vivo by FTSW, compared to untreated controls.

In the analysis of composite materials with heterogeneous microstructures, full resolution of the heterogeneities using classical numerical approaches can be computationally prohibitive. This paper presents a micromechanics-enhanced finite element formulation that accurately captures the mechanical behaviour of heterogeneous materials in a computationally efficient manner. The strategy exploits analytical solutions derived by Eshelby for ellipsoidal inclusions in order to determine the mechanical perturbation fields as a result of the underlying heterogeneities. Approximation functions for these perturbation fields are then incorporated into a finite element formulation to augment those of the macroscopic fields. A significant feature of this approach is that the finite element mesh does not explicitly resolve the heterogeneities and that no additional degrees of freedom are introduced. In this paper, hybrid-Trefftz stress finite elements are utilised and performance of the proposed formulation is demonstrated with numerical examples. The method is restricted here to elastic particulate composites with ellipsoidal inclusions but it has been designed to be extensible to a wider class of materials comprising arbitrary shaped inclusions., 28 pages, 12 figures, 2 tables

This paper presents an approach to constructing microstructural enrichment functions to local fields in non-periodic heterogeneous materials with applications in Partition of Unity and Hybrid Finite Element schemes. It is based on a concept of aperiodic tilings by the Wang tiles, designed to produce microstructures morphologically similar to original media and enrichment functions that satisfy the underlying governing equations. An appealing feature of this approach is that the enrichment functions are defined only on a small set of square tiles and extended to larger domains by an inexpensive stochastic tiling algorithm in a non-periodic manner. Feasibility of the proposed methodology is demonstrated on constructions of stress enrichment functions for two-dimensional mono-disperse particulate media., Comment: 27 pages, 12 figures; v2: completely re-written after the first review

The present paper deals with mathematical models of heat and moisture transport in layered building envelopes. The study of such processes generates a system of two doubly nonlinear evolution partial differential equations with appropriate initial and boundary conditions. The existence of the strong solution in two dimensions on a (short) time interval is proven. The proof rests on regularity results for elliptic transmission problem for isotropic composite-like materials., 34 pages, 3 figures

A two-layer statistically equivalent periodic unit cell is offered to predict a macroscopic response of plain weave multilayer carbon-carbon textile composites. Falling-short in describing the most typical geometrical imperfections of these material systems the original formulation presented in (Zeman and \v{S}ejnoha, International Journal of Solids and Structures, 41 (2004), pp. 6549--6571) is substantially modified, now allowing for nesting and mutual shift of individual layers of textile fabric in all three directions. Yet, the most valuable asset of the present formulation is seen in the possibility of reflecting the influence of negligible meso-scale porosity through a system of oblate spheroidal voids introduced in between the two layers of the unit cell. Numerical predictions of both the effective thermal conductivities and elastic stiffnesses and their comparison with available laboratory data and the results derived using the Mori-Tanaka averaging scheme support credibility of the present approach, about as much as the reliability of local mechanical properties found from nanoindentation tests performed directly on the analyzed composite samples., Comment: 28 pages, 14 figures

The paper describes the futures trading and aims to design the speculators trading strategy. The problem is formulated as the decision making task and such as is solved. The solution of the task leads to complex mathematical problems and the approximations of the decision making is demanded. Two kind of approximation are used in the paper: Monte Carlo for the multi-step prediction and iteration spread in time for the optimization. The solution is applied to the real-market data and the results of the off-line experiments are presented., {"references":["B. Graham, Security Analysis. New York: McGraw Hill Book Co., 1934,\n4. ISBN 0-07-144820-9.","J. Bogle, The First Index Mutual Fund: A History of Vanguard Index\nTrust and the Vanguard Index Strategy. Bogle Financial Center.","\"Stockcharts (http://www.stockcharts.org/).\"","D. Bertsekas, Dynamic Programming and Optimal Control. Nashua,\nUS: Athena Scientific, 2001, 2nd edition.","I. Nagy, L. Pavelkov'a, E. Suzdaleva, J. Homolov'a, and M. K'arn'y,\nBayesian decision making. Prague: CAS, 2005.","M. K'arn'y, B. J., T. V. Guy, L. Jirsa, I. Nagy, P. Nedoma, and L. Tesaˇr,\nOptimized Bayesian Dynamic Advising: Theory and Algorithms. London:\nSpringer, 2005."]}

Localization of plastic strain induced by softening can be objectively described by a regularized plasticity model that postulates a dependence of the current yield stress on a nonlocal softening variable defined by a differential (gradient) expression. This paper presents analytical solutions of the one-dimensional localization problem under certain special nonuniform stress distributions. The one-dimensional problem can be interpreted as describing either a tensile bar with variable cross section, or a beam subjected to a nonuniform bending moment. Explicit as well as implicit gradient formulations are considered. The evolution of the plastic strain profile and the shape of the load-displacement diagram are investigated. It is shown that even if the local constitutive law exhibits softening right from the onset of yielding, the global load-displacement diagram has a hardening part. The interplay between the internal length scales characterizing the material and the geometry is discussed., to appear in International Journal for Multiscale Computational Engineering

Nanotechnology and Construction in the 21 Century From nanotechnology to new production systems: the EU perspective Nanotechnology in civil engineering Nanotechnology: business and investment opportunities Integration of European nanotechnology research in construction Application of nanotechnology in construction - current status and future potential Nanotechnology for construction beyond the imagery Techniques and Instrumentation Focused Ion Beams (fib) - tools for serial sectioning of nanoindentation sites in cementitious materials Micro - an intermediate step to nano level analysis in concrete like composites Applications of DualBeam in the analysis of construction materials Synchrotron-Radiation X-ray Tomography: a method for the 3d verification of cement microstructure and its evolution during hydration Observation of the nanostructure of cement hydration by Soft X-ray Transmission Microscopy Study of pozzolan-cement interaction by Atomic Force Microscopy (afm) Estimation of the degree of hydration and phase constitutions by the SEM-BSE image analysis in relation to the development of strength in cement pastes and mortars Modification of cement paste with silica fume - a NMR study Modelling Modelling and temperature dependence of microstructure formation in cement based materials Numerical modelling of volume changes in cement-based systems at early ages Numerical modelling and experimental observations of the pore structure of cement-based materials Virtual concrete: working at the nanometer scale Evaluation of theoretical models for assessing interfacial properties in aged grc using fibre push-in test Moving-window representation of interfacial debonding in concrete Molecular modelling of confined fluids and solid-fluid interfaces in Portland cement and related materials Density functional calculation of elastic properties of portlandite and foshagite Exploring the micro-mechanics of open-ended pile driving via discrete element modelling Materials and Products Nanostructure of single carbon fibres investigated with synchrotron radiation High-performance nanostructured materials for construction Synthesis and characterization of nanoparticulate calcium aluminates Effects of water-cement ratio and curing age on the threshold pore width of hardened cement paste Effect of curing regime and type of activator on properties of alkali-activated fly ash Take a closer look: calcium sulphate based building materials in interaction with chemical additives Investigation of the micro-mechanical properties of underwater concrete Applications Thin films and coatings: atomic engineering The Nanohouse(TM) - an Australian initiative to develop the home of the future Building fapade integrated quantum dot concentrated solar electricity production Microsystems for the control of cable vibration Carbon nanotubes and their application in the construction industry Nano-science and -technology for asphalt pavements Natural roofing slate: the use of instrumented indentation technique to measure changes in the elastic modulus and hardness due to weathering Use of instrumented indentations for quality control of building materials Subject Index.

A well established framework of an uncoupled hierarchical modeling approach is adopted here for the prediction of macroscopic material parameters of the Generalized Leonov (GL) constitutive model intended for the analysis of flexible pavements at both moderate and elevated temperature regimes. To that end, a recently introduced concept of a statistically equivalent periodic unit cell (SEPUC) is addressed to reflect a real microstructure of Mastic Asphalt mixtures (MAm). While mastic properties are derived from an extensive experimental program, the macroscopic properties of MAm are fitted to virtual numerical experiments performed on the basis of first order homogenization scheme. To enhance feasibility of the solution of the underlying nonlinear problem a two-step homogenization procedure is proposed. Here, the effective material properties are first found for a mortar phase, a composite consisting of a mastic matrix and a fraction of small aggregates. These properties are then introduced in place of the matrix in actual unit cells to give estimates of the model parameters on macroscale. Comparison with the Mori-Tanaka predictions is also provided suggesting limitations of classical micromechanical models., Comment: to appear in International Journal for Multiscale Computational Engineering

This paper presents comparison of several stochastic optimization algorithms developed by authors in their previous works for the solution of some problems arising in Civil Engineering. The introduced optimization methods are: the integer augmented simulated annealing (IASA), the real-coded augmented simulated annealing (RASA), the differential evolution (DE) in its original fashion developed by R. Storn and K. Price and simplified real-coded differential genetic algorithm (SADE). Each of these methods was developed for some specific optimization problem; namely the Chebychev trial polynomial problem, the so called type 0 function and two engineering problems - the reinforced concrete beam layout and the periodic unit cell problem respectively. Detailed and extensive numerical tests were performed to examine the stability and efficiency of proposed algorithms. The results of our experiments suggest that the performance and robustness of RASA, IASA and SADE methods are comparable, while the DE algorithm performs slightly worse. This fact together with a small number of internal parameters promotes the SADE method as the most robust for practical use., Comment: 25 pages, 8 figures, 5 tables

Concrete is one of the most frequently used material in Civil Engineering. Nevertheless, as a highly heterogeneous material, it shows very complex non-linear behavior, which is extremely difficult to describe by a sound constitutive law. As a consequence, a numerical simulation of response of complex concrete structures still remains a very challenging and demanding topic.

Woven composites, i.e. composites reinforced with mutually interlaced systems of unidirectional fiber tows, belong to the most progressive material systems with applications ranging from strengthening of civil engineering structures to design of biocompatible medical implants. Therefore, understanding of overall behavior of these materials is a problem of considerable practical importance.

An efficient approach to the evaluation of effective elastic properties of carbon-carbon plain weave textile composites using the Mori-Tanaka method is presented. The method proves its potential even if applied to real material systems with various types of imperfections including the non-uniform waviness of the fiber-tow paths, both along its longitudinal direction and through the laminate thickness. Influence of the remaining geometrical parameters is accounted for by optimal calibration of the shape of the equivalent ellipsoidal inclusion. An application of the method to a particular sample of the carbon-carbon composite laminate demonstrates not only its applicability but also its efficiency particularly when compared to finite element simulations., 18 pages, 6 figures

This contribution presents a simple Finite Element model aimed at efficient simulation of layered glass units. The adopted approach is based on considering independent kinematics of each layer, tied together via Lagrange multipliers. Validation and verification of the resulting model against independent data demonstrate its accuracy, showing its potential for generalization towards more complex problems., 10 pages, 3 figures

Functionally graded materials (FGMs) are two-phase composites with continuously changing microstructure adapted to performance requirements. Traditionally, the overall behavior of FGMs has been determined using local averaging techniques or a given smooth variation of material properties. Although these models are computationally efficient, their validity and accuracy remain questionable, since a link with the underlying microstructure (including its randomness) is not clear. In this paper, we propose a modeling strategy for the linear elastic analysis of FGMs systematically based on a realistic microstructural model. The overall response of FGMs is addressed in the framework of stochastic Hashin-Shtrikman variational principles. To allow for the analysis of finite bodies, recently introduced discretization schemes based on the Finite Element Method and the Boundary Element Method are employed to obtain statistics of local fields. Representative numerical examples are presented to compare the performance and accuracy of both schemes. To gain insight into similarities and differences between these methods and to minimize technicalities, the analysis is performed in the one-dimensional setting., Comment: 33 pages, 14 figures

Finite element simulations on fibrous composites with nonlinear viscoelastic response of the matrix phase are performed to explain why so called two-point averaging schemes may fail to deliver a realistic macroscopic response. Nevertheless, the potential of two-point averaging schemes (the overall response estimated in terms of localized averages of a two-phase composite medium) has been put forward in number of studies either in its original format or modified to overcome the inherited stiffness of classical ”elastic” localization rules. However, when the material model and geometry of the microstructure promote the formation of shear bands, none of the existing two-point averaging schemes will provide an adequate macroscopic response, since they all fail to capture the above phenomenon. Several examples are presented here to support this statement.

Background: Several studies have shown that antihypertensive monotherapy is commonly insufficient to control blood pressure (BP) in hypertensive patients and that concomitant use of ≥2 drugs is necessary in ∼50% of these patients. The combination of an angiotensin-converting enzyme (ACE) inhibitor and a diuretic, delapril plus indapamide (D + I), has been shown to be effective and tolerable, with no interaction between the 2 components. Another widely used combination of ACE inhibitor and diuretic is lisinopril plus hydrochlorothiazide (L + H). Objectives: The aims of this study were to confirm the antihypertensive efficacy and tolerability of the fixed combination of D + I in mild to moderate hypertension, and to compare its therapeutic efficacy and tolerability with that of L + H. Methods: The antihypertensive efficacy and tolerability of a fixed combination of D + I (30-mg + 2.5-mg tablets once daily) or L + H (20-mg + 12.5-mg tablets once daily) in patients with mild to moderate hypertension were compared in a multinational, multicenter, randomized, 2-armed, parallel-group study. Eligible patients were aged 18 to 75 years and had a diastolic blood pressure (DBP) 95 to 115 mm Hg and a systolic blood pressure (SBP) ≤180 mm Hg, both measured in the sitting position. After a single-blind, placebo run-in period of 2 weeks, patients were randomized to receive 1 of the 2 treatments for a 12-week period. The primary efficacy end point was the BP normalization rate (ie, the percentage of patients with a sitting DBP ≤90 mm Hg) after 12 weeks of treatment. Secondary end points were as follows: (1) the responder rate (ie, the percentage of patients whose sitting DBP was reduced by ≥10 mm Hg from baseline or had a DBP ≤90 mm Hg after 12 weeks of treatment), (2) the percentage of patients with a DBP ≤85 mm Hg, and (3) changes in sitting SBP and DBP after 4, 8, and 12 weeks of treatment. Results: A total of 159 hypertensive patients (88 women, 71 men) were randomized to receive D + I (44 women, 36 men; mean [SD] age, 53 [11] years) or L + H (44 women, 35 men; mean [SD] age, 55 [10] years). No significant between-group differences were found in any of the primary or secondary end points of the study. Both combinations induced a significant reduction in sitting DBP and SBP from baseline (P

This paper presents discrete optimization of reinforced concrete structures based on an efficient combination of deterministic and stochastic optimization strategies. The deterministic optimization algorithm is used for the detailing of a reinforced concrete cross-section for a given combination of internal forces. The stochastic optimization algorithm, based on the Augmented Simulated Annealing, is used for the optimization of a whole structure in terms of basic structural characteristics like types of materials, dimensions of elements or profiles of steel bars. The implicit parallelization of genetic algorithm is implemented to reduce the overall computational time. Obtained preliminary results outline the direction of future research.

We report the observation of nonlinear piezoelectricity under hydrostatic pressures in a semiconductor. Optical measurements were carried out on CdTe-based piezoelectric quantum wells. At 2.7 GPa the field is changed by a factor of 2, as the result of a strong variation of the piezoelectric coefficient. Such a piezoelectric effect arises because the ionic and electronic contributions to the total polarization nearly cancel, as predicted by a recent ab initio calculation. Similar effects are expected in ZnTe, ZnSe, and InAs, where this near cancellation also occurs. \textcopyright{} 1996 The American Physical Society.

Raman-scattering experiments performed on n-type GaAs samples, doped with Te, Si, and S impurities, as a function of hydrostatic pressure in the indirect-gap range 4\char21{}9 GPa, reveal the bistable character of the related impurity level under optical illumination. A numerical simulation of our results shows that the negative-U model of Chadi and Chang is valid for reproducing the experimental data at low pressure. However, at very high pressures beyond 5\char21{}6 GPa, a positive-U description involving a small lattice relaxation is necessary to reproduce results for Te- and Si-doped samples. This demonstrates that the DX defect evolves under pressure, and that a transition from negative to positive U can occur at about 5\char21{}6 GPa.

The authors have evaluated 311 answers of Czech obstetricians to the questionnaire concerning their attitude towards pregnant women that want to terminate their labour by caesarean section. The questionnaire contained six model situations: (1) normal delivery; (2) previous caesarean section; (3) breech presentation; (4) previous delivery of an injured baby; (5) protracted labour and (6) caesarean section apparently indicated by another obstetrician. In each situation the obstetrician was encouraged to choose from five different answers. The results have revealed the lack of unanimity in some cases, 3, 4 and 5. Here we feel that the obstetrician should meet the wish of the woman. However, in those situations that are clear from the medical point of view and where there is no professional indication for a caesarean section, it is in accordance with the Czechoslovak rule of law not possible to meet the wish of the woman.

A method for the efficient realization of high-order Infinite Impulse Response (IIR) output-decimating State-Space Digital Filters (SSDF) is presented. By applying the state decimation and block processing to the nth-order narrow-band SSDFs, computational efficiency as well as low round-off noise levels are achieved. Further, the favorable behavior of certain SSDF forms with respect to the overflow limit cycles is retained. Such Fast State-Space IIR Decimators (FSSD) are simple to design, have multiplication rates comparable to Finite Impulse Response (FIR) decimators, have a highly parallel processing algorithm, and are very easy to implement on programmable signal processors. In the digital filter applications which do not require the linear-phase response, the FSSD may be considered as an alternative to a single-stage FIR decimator for moderate decimation factors.

Laminated glass units exhibit complex response as a result of different mechanical behavior and properties of glass and polymer foil. We aim to develop a finite element model for elastic laminated glass plates based on the refined plate theory by Mau. For a geometrically nonlinear description of the behavior of units, each layer behaves according to the Reissner-Mindlin kinematics, complemented with membrane effects and the von K\'{a}rm\'{a}n assumptions. Nodal Lagrange multipliers enforce the compatibility of independent layers in this approach. We have derived the discretized model by the energy-minimization arguments, assuming that the unknown fields are approximated by bi-linear functions at the element level, and solved the resulting system by the Newton method with consistent linearization. We have demonstrated through verification and validation examples that the proposed formulation is reliable and accurately reproduces the behavior of laminated glass units. This study represents a first step to the development of a comprehensive, mechanics-based model for laminated glass systems that is suitable for implementation in common engineering finite element solvers., Comment: 22 pages, 10 figures, 3 tables

The purpose of this paper is to propose an inexpensive micromechanics-based scheme for stiffness homogenization and strength estimation of mortars containing crushed bricks, known as cocciopesto. The model utilizes the Mori-Tanaka method to determine the effective stiffness, combined with estimates of quadratic invariants of the deviatoric stresses inside phases to predict the compressive strength. Special attention is paid to the representation of C-S-H gel layer around bricks and interfacial transition zone around sand aggregates, which renders the predictions sensitive to particle sizes. Several parametric studies are performed to demonstrate that the method correctly reproduces data and trends reported in available literature. Moreover, the model is based exclusively on parameters with clear physical or geometrical meaning and as such it provides a convenient framework for its further experimental validation., Comment: 12 pages, 6 figures, 1 table, v2: moderate revisions after the first round of review

Micromechanical homogenization is often carried out with Fourier-accelerated methods that are prone to ringing artifacts. We here generalize the compatibility projection introduced by Vond��ejc, Zeman & Marek [Comput. Math. Appl. 68, 156 (2014)] beyond the Fourier basis. In particular, we formulate the compatibility projection for linear finite elements while maintaining Fourier-acceleration and the fast convergence properties of the original method. We demonstrate that this eliminates ringing artifacts and yields an efficient computational homogenization scheme that is equivalent to canonical finite-element formulations on fully structured grids., 29 pages, 8 figures