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In this article, authors discuss new possibilities for the spatial design universal aesthetic development. Creative artistic means are conditioned by the human ability to comprehend and interpret objects in a particular context. Ideas of arts and science coexistence have been relevant since antiquity. The 20th century, especially the Bauhaus movement, gave a rational basis for conjoining artistic inspiration with the parametric constraints. Contemporary digital technologies provide new possibilities to enhance human creative potential by employing scientific methods. In search of material environment evaluation reference points, it is important to establish a robust connection of human mind and physical world. Subjectivity and intersubjectivity of experiences raise issues in human perception studies, involving both phenomenal and material processes. Embodied cognition reveals itself as an intuitive experience or discovery which provides a new perspective for the creative application. The authors aim to investigate the creative opportunities of automated shape generation systems. The main issue is to find a universal application of creative process analysis. Parametric constraints offer the opportunity to use statistical tools in art practice. These constraints are based on embodied cognition capabilities. Combined methods of qualitative and quantitative evaluation help to assess the contextual relevance of the object and to determine the cultural and pragmatic effectiveness of automated design solutions. The study offers theoretical and applied cross-disciplinary research direction to discover new creative means in material environment design, including architecture and urban planning.

The stochastic modelling of the microcracking and the force-displacement behaviour of the tensile steel reinforced tie using the lattice model is presented in the current article. The three-dimension problem of the modelling of the tie is reduced to the two-dimensional so as the main stiffness parameters of the concrete and the reinforcement of the two-dimensional model would be the same as for the three-dimensional. The concrete and steel obey the Hook law. All elastic constants, as well as dimensions of the tie, were assumed as the deterministic quantities except for the critical concrete tensile strains which were treated as a two-dimensional stationary uncorrelated truncated Gaussian random field. The discrete element approach and the explicit integration scheme have been used for the modelling. The estimations of the main parameters of the force-displacement behaviour stochastic process and other statistical indexes were obtained using 72 realization of the force-displacement behaviour of a chosen model. Extra two stochastic realizations of the two different models, as well as three deterministic models, were modelled to compare stochastic and deterministic behaviour of the force-displacement behaviour. The analysis showed that the force-displacement behaviour of the tie under tensile force cannot be treated as a Gaussian stochastic process when the p value is 0.05 at the small displacements and within the interval when the cracking of the concrete is very intensive. However, at the bigger displacements, when the cracking becomes less intensive, the tensile force can be treated as a Gaussian random variable.

Modern industrial enterprises require high accuracy and precision feedback systems to fulfil cutting edge requirements of technological processes. As demand for a highly accurate system grows, a thin gap between throughput and quality exists. The conjunction of ultrafast lasers and modern control strategies of mechatronic systems can be taken into account as an effective solution to reach both throughput and tolerances. In the present paper, the dynamic errors of the moving platform of the one degree of freedom stage, based on linear motor and air bearings, have been analyzed. A precision positioning system is investigated as a symmetric system which is based on symmetric linear motor. The goal of the present article is to investigate the controllers of the different architecture and to find the best controller that can ensure a stable and small dynamic error of the displacement of the stage platform at four different constant velocities of the moving platform. The relations between the controller order, velocity and the displacement dynamic error have been investigated. It is determined that higher-order controllers can reduce the dynamic error significantly at low velocities of the moving platforms: 1 and 5 mm/s. On the contrary, the low order controllers of 4th-degree polynomials of the transfer function can also provide small dynamic errors of the displacement of the platform., This article belongs to the Special Issue Symmetry in Optimization and Control with Real World Applications

This paper is devoted to investigating numerically, by finite element analysis (FEA), and analytically the influences and effects of laser processing of the surface of thin-plate, low-carbon structural steel. The plate mechanical properties&mdash, axial and flexural stiffnesses, force-deflection behavior and cross-section force-strain behavior&mdash, are investigated after different laser treatments. An analytical methodology of the estimation of the cross-section area of the laser-processed metal is also proposed in the present article, that can be applied to choosing the reasonable distance between the centers of the laser-processed tracks. The methodology takes into account the width of the laser-processed tracks and the distances between these tracks. The experimental, finite element numerical and analytical analyses showed that the laser treatments of the surface of the steel plate increase the yield point of the laser-processed metal and the axial and flexural stiffnesses of the plate.

In the present work, the adhesion strength of the atmospheric plasma sprayed Ni Al coating deposited on differently pretreated Al Mg alloy substrate was measured in order to evaluate the effectiveness of the substrate surface cathodic cleaning in comparison with conventional mechanical and chemical substrate preparation methods. The study includes brief characterization of the deposited coatings, microscopic examination of the interface zones, and coating adhesion measurements by a pull-off test. Cathodic cleaning enabled a significant increase in adhesion strength: compared with the best result obtained on conventionally pretreated specimens (22.8 MPa), adhesion strength was improved by 9.6 MPa (or 42%) and was equal to 32.4 MPa. The results obtained showed strong correlation with surface free energy and hydroxides' concentration at the surface. Statistical analysis of the experimental data has been performed in order to relate adhesion strength to the main surface parameters.

This paper presents a finite element method (FEM)-based fracture risk assessment in patient-specific osteoporotic lumbar vertebra L1. The influence of osteoporosis is defined by variation of parameters such as thickness of the cortical shell, the bone volume&ndash, total volume ratio (BV/TV), and the trabecular bone score (TBS). The mechanical behaviour of bone is defined using the Ramberg&ndash, Osgood material model. This study involves the static and nonlinear dynamic calculations of von Mises stresses and follows statistical processing of the obtained results in order to develop the patient-specific vertebra reliability. In addition, different scenarios of parameters show that the reliability of the proposed model of human vertebra highly decreases with low levels of BV/TV and is critical due to the thinner cortical bone, suggesting high trauma risk by reason of osteoporosis.

One of the most important task in application of the Discrete Element Method (DEM) to simulation of geomaterials is the adequacy of description of contact between interacting mineral particles. In most of the cases the elastic force is expressed by using Hertz model, while description of viscoelastic damping force is still under discussion. Recently various damping models described by different values of overlap power factor are used in DEM calculations. The general form of viscoelastic damping constant was presented, where well-known damping models present particular cases of general relationships. It known no one already existing models can precisely represent experimental results in most of the cases. In this paper general damping model comprising several existing approaches is developed. Here displacement power factor is evaluated on the basis of experiment results. It was found that the proposed approach gives more accurate simulation results of coefficient of restitution in comparison to already existing damping models.

In the present article, a version of the lattice or spring network method is proposed to model the mechanical response of elastic particulate composites with a high volume fraction of spherical particles and with a much weaker matrix compared to the stiffness of the particles. The main subject of the article is the determination of the axial stiffnesses of the springs of the cell. A comparison of the mechanical response of a three-dimensional particulate composite cube obtained using the finite element method and the proposed methodology showed that the efficiency of the proposed methodology increases with an increasing volume fraction of the particles.

In the present paper, a possibility of an approximation of elastic particulate composite with a network of elastic springs that undertake only axial forces is considered. It is assumed that the springs are equivalent to two hemispheres interacting through a weaker interface member. In a frame of the suggested approach, the description of the composite is limited to translational degrees of freedom, therefore, only a normal interaction between the spheres was considered. The methodology for calculation of the axial stiffness of the elastic springs and obtained solutions of the stiffness in explicit form are the main novelty of the article. A comparison of the stiffnesses of the springs obtained by the proposed methodology and by the three dimensional Finite Element Method (FEM) has shown a good agreement between them in a wide range of the ratio of the modulus of elasticity of the particles and matrix at four different distances between surfaces of the particles. A possibility of the approximation of particulate composite by springs was tested and discussed in details by comparing results of a mechanical response of a sample (under three different loading cases) modelled as a three dimensional solid and as a system comprised of the springs. The solutions were obtained by the FEM.

The adhesive–dissipative behavior of a microparticle under the oblique impact is investigated numerically and the new discrete element method (DEM)-compatible interaction model is elaborated. The modeling approach is based on the Derjaguin–Muller–Toporov model of normal interaction for the adhesive elastic contact. Adhesion hysteresis is specified by the loss of the kinetic energy governed by the fixed amount of the adhesion work, required to separate two adhesive contacting surfaces. This effect is captured in the new interaction model by adding an additional dissipative force component to normal contact during unloading and detachment. The essential feature of this approach, differing from that of the viscous damping model, is that, according to the proposed method, the amount of the dissipated energy is not influenced by the actual initial velocity during the entire contact. The influence of adhesion on slip friction is reflected by considering the adhesive normal force components in the Coulomb's law ...

The present paper analyzes a stress–strain state of a composite timber–concrete T cross section under a short-term pure bending. The behaviour of a bending moment in respect of a curvature of the cross section was investigated as well. It is assumed that the plane section hypothesis is valid and layers do not slip with respect to each other. The parabolic stress–strain diagram with a descending branch, according to MC90, was applied to the compression concrete while a linear elastic relationship was applied to the timber. The stress–strain state of the cross section was investigated from the beginning of the loading up to the stage exceeding ultimate limit state. The analysis was conducted by applying control of the curvature of the considered cross section. The influence of the tension fibre-reinforced polymer (FRP) and compression steel reinforcements on the stress–strain state of the cross section was also considered. The obtained analytical equations of the layered members were solved numerically. It was found out that the bearing capacity of the cross section is restricted mainly due to low strength of the timber and the tension reinforcement is more effective than the compression reinforcement.

An analytical and numerical study of the tangential contact of a spherical particle under varying combined normal-tangential loading is presented. The normal and tangential contact is described by the Hertz and regularized Coulomb laws. This study is focused on the analysis of the tangential displacement of the particle’s contact point under variable normal force and reevaluation of the procedures for calculation of the tangential force. The incremental displacement-driven and force-driven constitutive relationships are developed. The importance of an adequate numerical treatment of the tangential component of the contact force is shown for the slide mode, and the recommendations for its evaluation are proposed. The performance of the algorithm is demonstrated by solving the problem of the oblique impact of the spherical particle on the wall. The suggested methodology allows us to analyse the elastic and sliding effects of the tangential interaction more precisely than existing methodologies. Besides, the issue of the direction of the tangential force, when the Coulomb limit is reached, was reconsidered in one-dimensional case by taking three versions of the unit direction vector, which are based on the tangential elastic displacement, tangential stick force, and tangential relative velocity of the contact point of the particle.

The authors have proposed a relatively simple and convenient method for engineering purposes that allows one to simulate time-dependent viscoelastic properties of a multilayered composite element subjected to loading along layer joints. The method proposed is found to be of a good coincidence in comparison with the known analytical solution of a two-layered composite element. Numerical analysis is also performed adopting the model proposed for the deformational response of reinforced concrete elements.

This article covers the investigation of the catalyst waste (T.R.M 1 and T.R.M 2) produced in the reactor of oil catalytic cracking. The analysis of this waste was carried out. The properties of T.R.M 1 and T.R.M 2 were investigated and determined, the mineralogical analysis of catalyst waste was implemented, the analysis of thermal effects during the burning was performed. Catalyst waste materials investigated were used in a ceramic system (from 7  to 20  of the overall amount). It was identified that the optimal quantity of additive T.R.M 1 in formation mixes was 10%. With this amount of the additive, after the burning of formation mixes at 1050C temperature, ceramic systems with the following properties were formed: total contraction - up to 6.5, density of the system - larger than 1847 kg/m 3 , compressive strength - larger than 13 MPa, water absorption - up to 11 , and effective porosity - up to 21 . The identified optimum quantity of additive T.R.M 2 in the formation mix was 20 %. The obtained ceramic systems have the following parameters: total contraction - less than 10 %, density - higher than 1852 kg/m 3 , compressive strength - higher than 15 MPa, water absorption - less than 9 , and effective porosity - lower than 17 .

This paper analyses the compliance of the design codes calculation methods for punching shear resistance in reinforced concrete slabs STR 2.05.05:2005, E DIN 1045–1, ENV 1992–1â€1 EC 2, prEN 1992–1 [Final draft] EC 2, Model Code CEBâ€FIP 1990, BS 8110, ACI 318–99 to the experimental data. It has been analysed whether the difference in the results of the mean punching shear resistance received according to these methods and through experiments is statistically significant, when the level of significance value is 0,05. To analyse the significance of the difference of the means Student t test was used. An analysis was carried out to find out which methods show the least different resistance results from the experimental data. According to this analysis, a classification of methods was made. Student t test was applied to analyse in which methods the ratio between the punching shear resistance results obtained and the punching shear resistance results received through experiment is statistically insignificant. The level of significance value considered was 0,05. It has been determined that almost in all cases the difference between the punching shear resistance results received experimentally and theoretically is statistically significant. It has also been found out that generally the punching shear resistance can be calculated by applying the prEN 1992–1 [Final draft] EC 2 method. The best method to describe the punching shear resistance in minimally reinforced slabs is ACI 318. The worst results are obtained by applying ENV 1992–1â€1 EC 2 and E DIN 1045–1 methods. Kolonos-plokÅ¡tÄ—s jungties be skersinio armavimo veikiant sutelktajai apkrovai praspaudžiamojo stiprio normatyvinių skaiÄiavimo metodikų statistinÄ— analizÄ— Santrauka Darbe nagrinÄ—jamas gelžbetoninių plokÅ¡Äių praspaudžiamojo stiprio skaiÄiavimo normatyvinių metodikų STR 2.05.05:2005, E DIN 1045-1, ENV 1992-1-1 EC 2, prEN 1992-1 [Final draft] EC 2, Model Code CEB-FIP 1990, BS 8110, AC 318 atitikimas eksperimentiniams duomenims. IÅ¡analizuota, ar pagal Å¡ias metodikas apskaiÄiuotų ir eksperimentiÅ¡kai nustatytų praspaudžiamojo vidutinių stiprio reikÅ¡mių skirtumas statistiÅ¡kai reikÅ¡mingas, kai reikÅ¡mingumo lygmuo yra 0,05. Vidurkių skirtumo reikÅ¡mingumo analizei naudotas Stjudento t kriterijus. IÅ¡nagrinÄ—ta, pagal kurias metodikas apskaiÄiuotos stiprio reikÅ¡mÄ—s mažiausiai skiriasi nuo eksperimentinių duomenų. Tuo remiantis metodikoms priskirti rangai. Taikant Stjudento t kriterijų, iÅ¡analizuota, pagal kurias metodikas apskaiÄiuotų praspaudžiamojo stiprio reikÅ¡mių santykis su eksperimentiÅ¡kai nustatytomis praspaudžiamojo stiprio reikÅ¡mÄ—mis statistiÅ¡kai nereikÅ¡mingas. ReikÅ¡mingumo lygmuo imtas 0,05. Nustatyta, kad beveik visais atvejais skirtumas tarp eksperimentiÅ¡kai ir teoriÅ¡kai apskaiÄiuotų praspaudžiamojo stiprio reikÅ¡mių statistiÅ¡kai reikÅ¡mingas. Taip pat nustatyta, kad tiksliausiai praspaudžiamÄ…jį stiprį galima apskaiÄiuoti pagal prEN 1992-1 [Final draft] EC 2 metodikÄ…. Raktiniai žodžiai: gelžbetoninių plokÅ¡Äių praspaudžiamasis stipris, gelžbetoninių plokÅ¡Äių projektavimo normos, praspaudžiamojo stiprio statistinÄ— analizÄ—. First Published Online: 14 Oct 2010

The basic element of building, wall, must satisfty not only requirements for strength, stability, but also for cracking. Experiments and practice show that in many cases external decoration layers of external walls are cracked. It is because designers and builders do not take into consideration one of the basic conditions of the theory of layers—to satisfy compatibility of deformations of layers. Therefore it is necessary to know physical and mechanical properties of plasters such as strength limits of compressive and tensile strains and modulus of elasticity. In this paper, data and recommendations about strength and deformation properties of plaster are given, as well as regressive equations by which it is possible to choose the composition of composite cement-lime-sand mortar recording the following parameters: compressive and tensile strength, limit strain, modulus of elasticity. Analysis of experimental data shows that the compressive and tensile strength of mortar and modulus of elasticity mainly depend on the ratio cement/sand. Limit deformations depend on all 3 factors: cement, lime and sand. Article in Lithuanian. First Published Online: 26 Jul 2012

A methodology for prediction of the porosity of building ceramics caused by burning-out additives are proposed in the present article. The methodology is suitable when particles of burning-out additives is much larger than voids between particles of clay and filler. The proposed equations were verified by comparing theoretical calculations of the porosity with empirical data of ceramic articles of various compositions and with various amount of the burning-out additives. Crushed rubber was used as the burning-out additive. The Student test t was used for verifying statistic significance of difference between theoretical calculations and empirical data. The comparison showed a quite good agreement between the theoretical calculations and the empirical data. The proposed methodology can be useful to compose compositions of building ceramic articles, using burning-out additives, with desirable physical and mechanical properties – porosity, density, thermal conductivity, frost resistance, strength, modulus of elasticity and etc.