Vilnius Gediminas Technical University
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Experimental characterization of the self-healing capacity of cement based materials and its effects on the material performance: A state of the art report by COST Action SARCOS WG2
No full textHeuristically known at least since the first half of XIX century, the self-healing capacity of cement-based
materials has been receiving keen attention from the civil engineering community worldwide in the last
decade. As a matter of fact, stimulating and/or engineering the aforementioned functionality via tailored
addition and technologies, in order to make it more reliable in an engineering perspective, has been
regarded as a viable pathway to enhance the durability of reinforced concrete structures and contribute
to increase their service life.
Research activities have provided enlightening contributions to understanding the mechanisms of
crack self-sealing and healing and have led to the blooming of a number of self-healing stimulating
and engineering technologies, whose effectiveness has been soundly proved in the laboratory and, in a
few cases, also scaled up to field applications, with ongoing performance monitoring. Nonetheless, the
large variety of methodologies employed to assess the effectiveness of the developed self-healing technologies makes it necessary to provide a unified, if not standardized, framework for the validation and
comparative evaluation of the same self-healing technologies as above. This is also instrumental to pave
the way towards a consistent incorporation of self-healing concepts into structural design and life cycles
analysis codified approaches, which can only promote the diffusion of feasible and reliable self-healing
technologies into the construction market.The authors acknowledge the support from EU COST Action CA
15202 ‘‘SARCOS” (http://www.sarcos.eng.cam.ac.uk). E. Cuenca
and L. Ferrara acknowledge the financial support of the PoliMi
International Fellowships 2015 (PIF). T. Van Mullem and N. De
Belie acknowledge the grant (17SCIP-B103706-03) from the Construction Technology Research Program funded by Ministry of
Land, Infrastructure and Transport of Korean Government
Investigation and evaluation of railway ballast properties variation during technological processes
No full textRailway ballast (RB) layer has to limit tie movement by resisting vertical, lateral and longitudinal forces
from the train and the track, to reduce the stresses from train loads applied to the subgrade, thus limiting
permanent settlement. It also has to provide immediate water drainage from the track structure, to aid in
alleviating frost problems, to facilitate maintenance surfacing and lining operations, to provide support
for ties with the necessary resilience to absorb shock from dynamic loads. Secondary functions include
retarding vegetation and resisting effects of fouling from surface deposited materials, absorbing airborne
noise, providing adequate electrical resistance between rails, facilitating the redesign or reconstruction of
the track. These properties are obtained through the use of proper gradation crushed granite, by determining its proper laying and compacting technological parameters, by ensuring sufficient thickness
and profile of the layer. This paper presents statistical investigations of the four samples of crushed granite taken from transporter belt (TB), plant stockpile (PS), wagon (W) and railway construction (RC)
uncompacted layer used to RB course. The gradation (particle size distribution), density of crushed granite particles (DENP), water absorption (WA24), Deval index (MDE), Los Angeles coefficient (LARB coefficient)
and resistance to crushing (SZRB) of four samples were measured. Statistical parameters of crushed granite qualitative indicators, histograms, theoretical curves of normal distribution are presented. Their compliance with normal distribution was verified by employing the criteria of skewness, kurtosis, Pearson,
Shapiro-Wilk and Kolmogorov-Smirnov. Dependance of standard deviations of percent passing through
sieves on the means of percent passing through these sieves was obtained from regression analysis.
The use of Kruskal-Wallis test by ranks showed that means obtained in different sample-taking locations
did not differ statistically. The maximum value of standard deviation of this dependance, equal to mean
of 50% percent passing, was used to evaluate the homogeneity of crushed granite used to construct the
ballast layer according to the variation of its gradation. Absolute allowable error of minimum sample size
n, equal to 5%, 10%, 15% and 20%, was calculated. Investigation results indicated that due to segregation
the homogeneity of the gradation of crushed granite used to construct the ballast layer from its production site to its exploitation site decreased by 78%. During the technological processes of loading, transporting and spreading the gradation has hardly changed
Įžvalgi investavimo globaliose akcijų rinkose strategija siekiant grąžos tvarumo
Get PDFThe increasing amount of available information on the activities of stock markets and issuers, a rapid expansion of stock markets (increasing market capitalization, growing number of listed companies) and the intensive growth of globalization processes, does not always help investors to make effective investment decisions. Therefore, the issue of stock markets and stock selection for the formation of investment portfolios is particularly important to investors. Although, the issuer’s financial data and the databases of financial markets are very detailed and able to characterise many of the features of the subject being analysed, these data are not fully provided for the purpose of sustainable investments. This problem is being solved in the dissertation – searching ways, how to apply and combine the most commonly used individual methods for equity market selection, stocks selection and investment portfolio formation, thus using statistical data, which are already available, for assessing the markets of different development levels and for the selection of particular stocks to achieve the investment return sustainability.
The aim of the dissertation is to develop a methodology for the implementation of intelligent investment strategy in equity markets, which provides opportunities for achieving investment return sustainability in financial markets for various investors.
The dissertation consists of an introduction, three chapters, general conclusions, literature reference list (283 publications), list of scientific publications by the author on the topic of the dissertation (23 publications), summary in Lithuanian and 8 annexes. The volume of the dissertation is 157 pages, excluding annexes. Text contains 20 numbered formulas, 36 figures and 26 tables.
The factors of globalization, which have an influence on financial markets behaviour, were analysed, the possibilities of classical investment methods application for the stock markets and particular stock selection as well as the links between various economic indicators and stock market returns were examined, the concepts of investment return sustainability and intelligent investment strategy were expanded in the first chapter. The methodology of stock markets evaluation, stock selection and intelligent investment strategy for investor is proposed in the second chapter. Experimental and numerical results of the intelligent investment strategy implementation are presented in the final chapter.
23 articles on the topic of the dissertation has been published: six of them in the journals, abstracted and indexed in scientific international databases, three in other peer-reviewed scientific journals, eleven in conferences proceedings and three in the conferences proceedings referred by the Clarivate Analytics Web of Science. The results of the dissertation were presented at ten scientific conferences
The robust finite volume schemes for modeling non-classical surface reactions
Get PDFA coupled system of nonlinear parabolic PDEs arising in modeling of surface reactions
with piecewise continuous kinetic data is studied. The nonclassic conjugation conditions are
used at the surface of the discontinuity of the kinetic data. The finite-volume technique and the
backward Euler method are used to approximate the given mathematical model. The monotonicity,
conservativity, positivity of the approximations are investigated by applying these finite-volume
schemes for simplified subproblems, which inherit main new nonstandard features of the full
mathematical model. Some results of numerical experiments are discussed
The sustainability narrative in contemporary architecture: falling short of building a sustainable future
No full textSustainability has emerged, arguably, as the premiere mission of contemporary architecture.
Green assessment tools abound, consultancy services flourish, buildings are marketed on the basis
of sustainability performance, and government, media, and corporations seem preoccupied with
assessing the quality of the built environment through a green lens. Yet for all the effort, and indeed
for all the progress made, fundamental issues resistant to the structural change that is essential for
genuine sustainability remain. This paper reviews the state of play of sustainability across the urban
landscape. It considers the road travelled so far, and points out some of the major challenges that
lie ahead
Modeling of combined slip and finite sliding at spherical grain contacts
No full textThe present paper is aimed at developing the analytical description of the interaction of two contacting spheres for several classes of slip and sliding trajectories, typical in the experimental testing. The analysis accounts for memory effects in the slip regime and configurational effects in the sliding regime, expressed in terms of an active loading surface and memory surfaces within the space of contact forces. Analytical relations for contact response are derived for linear and piecewise-linear motion trajectories of the sphere. The problem of multiple contact interaction of the sphere moving over the regularly packed granular bed is also considered analytically. It is demonstrated that the dual contact activation-separation processes occur within the combined slip–sliding modes, essentially affecting the distribution of contact tractions. The results obtained are relevant for the class of contact problems requiring analysis of interaction of slip and sliding displacements, in particular in testing grain contact interaction aimed at specification of elastic, frictional and wear parameters
Numerical simulation of nonlocal delayed feedback controller for simple bioreactors
Get PDFThe new nonlocal delayed feedback controller is used to control the production of drugs in a simple bioreactor. This bioreactor is based on the enzymatic conversion of substrate into the required product. The dynamics of this device is described by a system of two nonstationary nonlinear diffusion-reaction equations. The control loop defines the changes of the substrate concentration delivered into the bioreactor at the external boundary of the bioreactor depending on the difference of measurements of the produced drug delivered into the body and the flux of the drug prescribed by a doctor in accordance with the therapeutic protocol. The system of PDEs is solved by using the finite difference method, the control loop parameters are defined from the analysis of stationary linearized equations. The stability of the algorithm for the inverse boundary condition is investigated. Results of computational experiments are presented and analysed
WEBIRA - comparative analysis of weight balancing method
Get PDFThe attributes weight establishing problem is one of the most important MCDM tasks. This study summarizes weight determining approach which is called WEBIRA (WEight Balancing Indicator Ranks Accordance). This method requires to solve complicated optimization problem and its application is possible by carrying out non trivial calculations. The efficiency of WEBIRA and other MCDM methods – SAW (Simple Additive Weighting) and EMDCW (Entropy Method for Determining the Criterion Weight) compared for 4 different data normalization methods. The re-sults of the study revealed that more sophisticated WEBIRA method is significantly efficient for all considered numbers of alternatives. Efficiency of all methods decreases with increasing number of alternatives, but WEBIRA is still applicable, while appli-cation of other methods is impossible as the number of alternatives is greater than 11. WEBIRA is the least affected by the data normalization, while EMDCW is the most affected method
Panel data analysis of public and private debt and house price influence on GDP in the European Union countries
No full textThe panel data analysis of the influence of change in real public debt, real private debt, and deflated house prices on the
GDP in selected European countries is performed. Least squares and autoregressive AR(p) model were used with crosssection
and period both fixed by dummy variables. The research has confirmed strong negative influence of public debt with
zero, one and two year’s lags as an independent variable on the GDP as the dependent variable. This is not surprising
having in mind limited functionality of the European central bank as a lender of the last resort for the countries of the monetary
union, that is, for the most of the analysed countries. This finding also confirms the necessity of the transformation of the
European Monetary Union to the European Financial Union. Private debt has definite positive influence on the GDP as the
dependent variable. It was confirmed by measuring this influence with zero, one and two and three years lags, but this positive
influence was 2–3 times lower than the negative influence of public debt on the GDP. House prices unlagged have similar
absolute value of positive influence on the GDP coefficient as the absolute value of the negative influence of lagged public debt,
according to the regression coefficients received. However, house prices, leading by 2 years, have negative influence on the
GDP, but this influence is almost 5 times weaker than the negative influence of unlagged public debt
Heidegeriškoji naudos ontologija
No full textStraipsnyje mėginama apsvarstyti naudos ontologiją. Laikoma, kad mūsų laikais esmingą utilitaristinę nuostatą
– nesvarbu, ar naudos siekimas vertinamas pozityviai, ar negatyviai, – grindžia subjekto ontologija.
Reikia atgauti tikroviškąją naudos prasmę, subjekto ontologiją keičiant Dasein ontologija. Kaip visada, heidegeriškajame
mąstyme svarbi istorinė dimensija, ontologijos virsmą siejant su įsiklausymu į jos graikiškąsias
ir ikisokratiškąsias ištakas. Čia interpretuojame heidegeriškąjį turbūt pirmosios Vakarų ontologinės ištaros –
Anaksimandro išlikusio fragmento – apmąstymą, kuriame nauda pasirodo kaip būties vardas. Parodome, kaip
Būtyje ir laike suformuluotos struktūros atpažįstamos ir Vakarų ontologinės pradžios apmąstyme