Strength analyses of screws for femoral neck fractures

This article represents a multidisciplinary approach to biomechanics (engineering + medicine) in the field of "collum femoris" fractures. One possible treatment method for femoral neck fractures, especially for young people, is the application of cancellous (i.e. lag or femoral) screws (with full or cannulated cross-section) made of Ti6Al4V or stainless steel. This paper therefore aims to offer our own numerical model of cancellous screws together with an assessment of them. The new, simple numerical model presented here is derived together with inputs and boundary conditions and is characterized by rapid solution. The model is based on the theory of beams on an elastic foundation and on 2nd order theory (set of three differential 4th order equations, combination of pressure and bending stress-deformation states). It presents the process for calculating displacements, slopes, bending moments, stresses etc. Two examples (i.e. combinations of cancellous screws with full or cannulated cross-section made of stainless steel or Ti6Al4V material) are presented and evaluated (i.e. their displacement, slopes, bending moments, normal forces, shearing forces and stresses). Future developments and other applications are also proposed and mentioned.Web of Science38583481

Properties of operators occurring in the Penrose transform

summary:It is shown that operators occurring in the classical Penrose transform are differential. These operators are identified depending on line bundles over the twistor space

Mapping rational rotation-minimizing frames from polynomial curves on to rational curves

Given a polynomial space curve r(ξ) that has a rational rotation–minimizing frame (an RRMF curve), a methodology is developed to construct families of rational space curves r˜(ξ) with the same rotation–minimizing frame as r(ξ) at corresponding points. The construction employs the dual form of a rational space curve, interpreted as the edge of regression of the envelope of a family of osculating planes, having normals in the direction u(ξ)=r′(ξ)×r″(ξ) and distances from the origin specified in terms of a rational function f(ξ) as f(ξ)/‖u(ξ)‖. An explicit characterization of the rational curves r˜(ξ) generated by a given RRMF curve r(ξ) in this manner is developed, and the problem of matching initial and final points and frames is shown to impose only linear conditions on the coefficients of f(ξ), obviating the non–linear equations (and existence questions) that arise in addressing this problem with the RRMF curve r(ξ). Criteria for identifying low–degree instances of the curves r˜(ξ) are identified, by a cancellation of factors common to their numerators and denominators, and the methodology is illustrated by a number of computed examples

Efficient methods of automatic calibration for rainfall-runoff modelling in the Floreon+ system

Calibration of rainfall-runoff model parameters is an inseparable part of hydrological simulations. To achieve more accurate results of these simulations, it is necessary to implement an efficient calibration method that provides sufficient refinement of the model parameters in a reasonable time frame. In order to perform the calibration repeatedly for large amount of data and provide results of calibrated model simulations for the flood warning process in a short time, the method also has to be automated. In this paper, several local and global optimization methods are tested for their efficiency. The main goal is to identify the most accurate method for the calibration process that provides accurate results in an operational time frame (typically less than 1 hour) to be used in the flood prediction Floreon(+) system. All calibrations were performed on the measured data during the rainfall events in 2010 in the Moravian-Silesian region (Czech Republic) using our in-house rainfall-runoff model.Web of Science27441339

Methodology of Surveying Real Estate for the Assessment of Selected Types of Non-residential Buildings

Cílem diplomové práce je návrh postupu provádění ohledání nebytových objektů. V diplomové práci bude provedena analýza metod používaných při oceňování nemovitostí se zaměřením na místní šetření. Na základě této analýzy požadavků jednotlivých metod na vstupní údaje pro ocenění a jejich vyhodnocení budou stanovena společná i specifická doporučení pro přípravu podkladů k ocenění nebytových objektů a pro místní šetření. Účelem diplomové práce je pomoc znalci s přípravou podkladů pro vypracování posudku.The aim of the thesis is to design procedure of inspection non-residential immovable property. There will be done analysis of methods used to evaluate immovable property, with focus on local investigation in the master thesis. Based on this analysis there will be set common and specific recommendation for preparation of source data, for evaluation of buildings, and for local investigation in case of evaluation buildings. The purpose of this thesis is to help experts with preparation of source data to make evaluating report.

Development and verification of model variable density flow in fractured media

Tato bakalářská práce je zaměřena na výpočet úloh podzemního proudění s nehomogenní hustotou. Problematika zde řešená je v kontextu s konstrukcí úložišť jaderného odpadu a možného průběhu kontaminace v případě havárie, nebo průběhu znečištění podzemních vod. Další oblast použití je v modelování podzemního proudění v přímořských oblastech, kde dochází k ovlivnění proudění slanou mořskou vodou. V úvodu je charakterizována fyzikální podstata podzemního proudění, jeho zjednodušení, ovlivnění hustotou a změnou proudění v okolí a uvnitř pukliny. V následující části je popsán matematický model a zároveň software použitý na vlastní modelování. Byla doplněna nová vlastnost ovlivňující proudění, hustota. Její vliv na proudění je demonstrován na testovacích úlohách.This bachelor diploma is focused on calculation problems of variable density of groudwater flow, concerning problems of construction deep geological repository of radioactive waste and possible contamination in case of accident, or groundwater pollution. Another area of usage is modelling underground flow in seaside areas, where the flow is being affected by seawater. In the introduction is characterized physical matter of underground flow, its simplification, affection by density and change in flow in a rift and its surroundings. In the next part of work is described mathematical model and software used for modelling. New attribute affecting flow was added, the density. Its effect on flow is demonstrated on excersisses