Modelling of three-point bending test of beams with steel inclusion situated in the middle of the span

The aim of this paper is to present the numerical model of the fracture response of the test specimens with a steel inclusion in the shape of the prisms which length is equal to the specimen’s width. Specially designed fine-grained cement-based matrix specimens of the nominal dimension 40 x 40 x 160mm with inclusion of 8 x 8 x 40mm and central edge notch serves to determine of the influence of the interfacial transition zone on the effective mechanical fracture parameters of composite. The numerical models of three-point bending test of these specimens are created in ATENA software

Model Based Control of Moisture Sorption in a Historical Interior

This paper deals with a novel scheme for microclimate control in historical exhibition rooms, inhibiting moisture sorption phenomena that are inadmissible from the preventive conservation point of view. The impact of air humidity is the most significant harmful exposure for a great deal of the cultural heritage deposited in remote historical buildings. Leaving the interior temperature to run almost its spontaneous yearly cycle, the proposed non-linear model-based control protects exhibits from harmful variations in moisture content by compensating the temperature drifts with an adequate adjustment of the air humidity. Already implemented in a medieval interior since 1999, the proposed microclimate control has proved capable of permanently maintaining constant a desirable moisture content in organic or porous materials in the interior of a building.

Control System Design Based on a Universal First Order Model with Time Delays

An original modelling approach for SISO systems is presented, based on a first order model with more than one delay in its structure. By means of this model it is possible truly to hit off the properties of systems which are conventionally described by higher order models. The identification method making use of a relay feedback test combined with transient responses of the system has proved to be suitable for assessing the model parameters. With respect to its plain structure the model is well suited to be applied in the framework of an internal model control scheme (IMC). The resultant control algorithm with only one optional parameter is very simple and can easily be implemented, for example by means of a programmable controller (PLC)

Anisochronic Internal Model Control Design

The features of internal model control (IMC) design based on the first order anisochronic model are investigated in this paper. The structure of the anisochronic model is chosen in order to fit both the dominant pole and the dominant zero of the system dynamics being approximated. Thanks to its fairly plain structure, the model is suitable for use in IMC design. However, use of the anisochronic model in IMC design may result in so-called neutral dynamics of the closed loop. This phenomenon is studied in this paper via analysing the spectra of the closed loop system

Experience of Implementing Moisture Sorption Control in Historical Archives

This paper deals with a novel approach to inhibiting the harmful impact of moisture sorption in old art works and historical exhibits preserved in remote historic buildings that are in use as depositories or exhibition rooms for cultural heritage collections. It is a sequel to the previous work presented in [2], where the principle of moisture sorption stabilization was explained. Sorption isotherm investigations and EMC control implementation in historical buildings not provided with heating are the main concern in this paper. The proposed microclimate adjustment consists in leaving the interior temperature to run almost its spontaneous yearly cycle, while the air humidity is maintained in a specific relationship to the current interior temperature. The interior air humidity is modestly adjusted to protect historical exhibits and art works from harmful variations in the content of absorbed moisture, which would otherwise arise owing to the interior temperature drifts. Since direct measurements of moisture content are not feasible, the air humidity is controlled via a model-based principle. Two long-term implementations of the proposed microclimate control have already proved that it can permanently maintain a constant moisture content in the preserved exhibits.

Meromorphic observer-based pole assignment in time delay systems

summary:The paper deals with a novel method of control system design which applies meromorphic transfer functions as models for retarded linear time delay systems. After introducing an auxiliary state model a finite-spectrum observer is designed to close a stabilizing state feedback. The observer finite spectrum is the key to implement a state feedback stabilization scheme and to apply the affine parametrization in controller design. On the basis of the so- called RQ-meromorphic functions an algebraic solution to the problem of time- delay system stabilization and control is presented that practically provides a finite spectrum assignment of the control loop

Polynomial approximation of quasipolynomials based on digital filter design principles

This contribution is aimed at a possible procedure approximating quasipolynomials by polynomials. Quasipolynomials appear in linear time-delay systems description as a natural consequence of the use of the Laplace transform. Due to their infinite root spectra, control system analysis and synthesis based on such quasipolynomial models are usually mathematically heavy. In the light of this fact, there is a natural research endeavor to design a sufficiently accurate yet simple engineeringly acceptable method that approximates them by polynomials preserving basic spectral information. In this paper, such a procedure is presented based on some ideas of discrete-time (digital) filters designing without excessive math. Namely, the particular quasipolynomial is subjected to iterative discretization by means of the bilinear transformation first; consequently, linear and quadratic interpolations are applied to obtain integer powers of the approximating polynomial. Since dominant roots play a decisive role in the spectrum, interpolations are made in their very neighborhood. A simulation example proofs the algorithm efficiency. © Springer International Publishing Switzerland 2016

Strategy Competitive Fight

Diplomová práce se zabývá nalezením takové strategie, která umožní zavedené firmě setrvání v pozici lídra trhu spotřebitelských úvěrů v České republice. K tomu potřebuje získat pokud možno detailní informace o aktivitách konkurence, vývoji oborového prostředí a trendu preferencí koncového zákazníka. Na základě těchto informací formuluje několik možných strategických variant včetně jejich dopadu na zákazníka, obchodní partnery a interní chod firmy.The thesis deals with finding such a competitive strategy, which enables a well-established Copany to remain on the leading edge of sales finance market in the Czech Republic. To do that, it is necessary to acquire as detailed information about competitors´ activities, professional environment development and end-user preferences trend, as possible. Based on this information it proposes possible models of strategic options including the impact on customers, business partners and internal issues.

Effect of the Mechanical Fracture Parameters of Inclusion on Fracture Behaviour of Cement Composite

This paper concerns the results of research into the effect of the mechanical fracture parame- ters of inclusion material on the fracture response of specially designed cement-based composite speci- mens. These specimens of the nominal dimensions 40 × 40 × 160 mm with inclusion in the shape of prisms with nominal dimensions of 8 × 8 × 40 mm were pro- vided with an initial central edge notch and tested in the threee-point bending configuration. The aim of this paper is to analyse the effect of the mechanical fracture parameters of inclusions material on the ef- fective mechanical fracture parameters of cement-based composite. The results of this research indicate the de- pendence of the effective mechanical fracture parame- ters of cement-based composite on the Young’s modulus of inclusion material

Changes of TMZ Steel Structure during Welding and Subsequent Straightening with Oxy - Acetylene Flame

Diplomová práce se zabývá vlastnostmi termomechanicky zpracovaných ocelí, jejich výrobou a mechanismem jejich zvýšených mechanických vlastností. Pro experimentální část byla vybrána TMZ ocel v jakosti S355MC, ze které byly vyrobeny a svařeny vzorky metodou 135 (MAG). Následně byla u jednoho vzorku provedena simulace rovnání kyslíko-acetylénovým plamenem při teplotě do 800 °C, další vzorek byl ponechán pouze ve svařeném stavu. Na těchto vzorcích byly provedeny nedestruktivní i destruktivní zkoušky, které slouží k porovnání změn mechanických vlastností a změn struktury v oblastech svarového spoje pro oba případy.The diploma thesis deals with the properties of thermomechanically processed steels, their production and the mechanism of their increased mechanical properties. For the experimental part, the samples were manufactured from the TMZ steel of steel grade S355MC and welded using the 135 (MAG) method. Subsequently, one of the samples was simulated to straightening using oxygen-acetylene flame at a temperature up to 800 °C, while the other sample was left in the welded state. To compare changes in mechanical properties and changes in the structure in the close vicinity of the weld for both cases, non-destructive and destructive tests were performed.345 - Katedra mechanické technologievýborn