Calibration of parameters of mathematical models is still a tough task in several engineering problems. Many of the models adopted for the numerical simulations of real phenomena, in fact, are of empirical derivation. Therefore, they include parameters which have to be calibrated in order to correctly reproduce the physical evidence. Thus, the success of a numerical model application depends on the quality of the performed calibration, which can be of great complexity, especially if the number of parameters is higher than one. Calibration is traditionally performed by engineers and researchers through manual trial-and-error procedures. However, since models themselves are increasingly sophisticated, it seems more proper to look at more advanced calibration procedures. In this work, in particular, an optimization technique for a multi-parameter calibration is applied to a two-phase depth-averaged model, already adopted in previous works to simulate morphodynamic processes, such as, for example, the dike erosion by overtopping.
Measurement of leaf area is commonly used in many horticultural research experiments, but it is generally destructive, requiring leaves to be removed for measurement. Determining the individual leaf area (LA) of bedding plants like pot marigold (Calendula officinalis L.), dahlia (Dahlia pinnata), sweet William (Dianthus barbatus L.), geranium (Pelargonium × hortorum), petunia (Petunia × hybrida), and pansy (Viola wittrockiana) involves measurements of leaf parameters such as length (L) and width (W) or some combinations of these parameters. Two experiments were carried out during spring 2010 (on two pot marigold, four dahlia, three sweet William, four geranium, three petunia, and three pansy cultivars) and summer 2010 (on one cultivar per species) under greenhouse conditions to test whether a model could be developed to estimate LA of bedding plants across cultivars. Regression analysis of LA versus L and W revealed several models that could be used for estimating the area of individual bedding plants leaves. A linear model having LW as the independent variable provided the most accurate estimate (highest R2, smallest mean square error, and the smallest predicted residual error sum of squares) of LA in all bedding plants. Validation of the model having LW of leaves measured in the summer 2010 experiment coming from other cultivars of bedding plants showed that the correlation between calculated and measured bedding plants leaf areas was very high. Therefore, these allometric models could be considered simple and useful tools in many experimental comparisons without the use of any expensive instruments. and F. Giuffrida ... [et al.].
The paper is focused on theoretical design and experimental realization of an automatized process of user-friendly definition of a region of interest and its accurate scanning with a terrestrial optical scanner. A measurement system is designed and analysed. Simplicity and robustness of such a process promises wide usage in many geodetic applications. Moreover, a calibration procedure is described and tested as well. The theoretical model and the measurement device is realized and verified by an experiment. and Článek se zabývá teoretickým návrhem a experimentální realizací automatizovaného procesu uživatelsky komfortního zadání oblasti zájmu a jejího následného přesného skenování laserovým skenerem. Je navržena a analyzována měřická sestava, která svou jednoduchostí a robustností slibuje široké využití v řadě geodetických aplikacích. Dále je navržen a testován metodický postup kalibrace procesu. Teoretický návrh a měřická sestava je realizována a ověřena experimentálně.
The use of electromagnetic (EM) soil moisture probes is proliferating rapidly, in two broad domains: in field and laboratory research; and in strongly practical applications such as irrigation scheduling in farms or horticultural enterprises, and hydrological monitoring. Numerous commercial EM probes are available for measurement of volumetric water content (θv), spanning a range of measurement principles, and of probe dimensions and sensing volumes. However probe calibration (i.e. the relationship of actual θv to probe electrical output) can shift, often substantially, with variations in parameters such as soil texture, organic matter content, wetness range, electrical conductivity and temperature. Hence a single-valued, manufacturer-supplied calibration function is often inadequate, forcing the user to seek an application-specific calibration. The purpose of this paper is to describe systematic procedures which probe users can use to check or re-determine the calibration of their selected probe(s). Given the wide diversity of operating principles and designs of commercially-available EM probes, we illustrate these procedures with results from our own calibrations of five different short probes (length of 5 to 20 cm). Users are strongly recommended to undertake such calibration checks, which provide both a) pre-use experience, and b) more reliable in-use data. and Používanie elektromagnetických (EM) snímačov vlhkosti pôdy sa rýchlo rozširuje tak v terénnom výskume, ako aj v laboratóriu. Sú používané v praktických aplikáciách ako je riadenie závlah na farmách a záhradách, ako aj v hydrologickom monitoringu. Pre meranie vlhkosti pôdy (θv) sú dostupné početné typy komerčných EM snímačov, založených na viacerých princípoch merania a snímače majú rozdielnu veľkosť snímaných objemov pôdy. Kalibračné krivky takýchto snímačov (t.j. závislosti medzi reálnou vlhkosťou pôdy θv a elektrickým výstupom snímača) sa môžu posúvať - niekedy podstatne - a to v závislosti od rozdielnych parametrov pôdy, ako je jej textúra, obsah organických látok, rozsah vlhkostí, elektrická vodivosť a teplota. Z toho vyplýva, že jednoznačná kalibračná krivka, dodávaná výrobcom je často neadekvátna, čo núti užívateľa snímač kalibrovať v špecifických podmienkach. Cieľom tohto príspevku je opísať procedúry, ktoré môžu byť použité užívateľmi pri rekalibrácii vybraných typov snímačov. Berúc do úvahy širokú paletu princípov EM snímačov, ilustrujeme tieto procedúry výsledkami vlastných kalibračných testov na piatich typoch krátkych snímačov (dĺžka od 5 do 20 cm). Užívateľom odporúčame rekalibráciu komerčných snímačov, ktorými získajú predbežné skúsenosti a spoľahlivejšie výsledky pri meraní vlhkosti pôdy.
Geodetic and geodynamic applications of satellite Doppler observations require a proper knowledge of receiver parameters corresponding to avilable reduction software. In this paper different methods used for calibration of Doppler receivers are summarized. One of them based on GEODOP-III program and broadcast ephemeris is presented and checked by test computations.
The paper presents an issue of determination of the vertical index error of spatial optical scanners. The procedure for numerical calibration is presented and the methodology is verified with experimental data. The proposed procedure is basically intended for numerical calibrations of measured point-cloud data, and also to improve the output quality and to eliminate costs of mechanical calibrations of optical scanners. and V práci je analyzována problematika určení velikosti chyby čtení svislého úhlu při měření prostorovými optickými skenery. Je představen postup jejího numerického určení a metodika je aplikována a ověřena na experimentálních datech. Navržený postup může sloužit k numerickým kalibracím měřených dat mračen bodů, výrazně zvýšit kvalitu výstupů, a také eliminovat náklady vybrané mechanické kalibrace optických skenerů.
This project deals with calibration of experimental texturemetre at tensile and compressive loading. We have used the samples of European walnuts for the etalon calibration. We tested compressive loading and on the walnut. Measurements was realised on Stentor Andilog 1000 and on the developed texturemetre. These equipment recorded force and displacement. We could use those data, which were gathered to create dependencies of every device. We created correlations for each measurement. Also we could determine the accuracy of the equipments with apply of the coefficient of correlation. We could determine the linearity of the equipment with the help of the regression method. and Táto práca sa zaoberá kalibráciou vývojového textúrometra pri zaťažení materiálu tlakom. Pre dosiahnutie kalibrácie boli merané vzorky orecha vlašského zaťažené na tlak. Merania boli realizované na zariadení Stentor Andilog 1000 a na vývojovej trhačke. Prístroje zaznamenávali silu a premiestnenie. Z týchto údajov potom boli zostrojené grafické závislosti. Boli vytvorené korelačné tabuľky pre jednotlivé merania. Pomocou koeficientu korelácie sme zistili, že meracie zariadenia sú s vysokou pravdepodobnosťou zhodné. Pomocou regresnej metódy bolo dokázané, že existuje nelinearita pri vyššom zaťažení.
The paper deals with the realization of the optimal eye model mainly from the structural point of view, physical principles and mathematical modelling of the proposed device. The model eye is a proposed device (standard) designed to provide objective metrological control of non-contact eye tonometers that evaluate intraocular pressure. This is important for proper diagnosis of patients during ocular control. Using a model eye, we will be able to ensure correct measurement of this quantity (intraocular pressure) in ophthalmological practice, on non-contact eye tonometers. This variable is crucial for the correct diagnosis of elevated intraocular pressure, which is a major symptom of glaucoma disease. The paper presents the understanding of contemporary issues in eye tonometry and gives a vision for the future, for objective metrological provision of these devices. and Příspěvek se zabývá matematickým modelem fyzikálních principů oční rohovky a jeho konstrukční realizací. Modelové oko představuje etalon určený pro objektivní metrologickou kalibraci bezkontaktních očních tonometrů vyhodnocujících nitrooční tlak. Zjištění jeho velikosti je důležité pro správnou diagnostiku pacientů v oční ambulanci. Pomocí modelového oka jsme schopni zabezpečit spolehlivé měření nitroočního tlaku bezkontaktními očními tonometry v oftalmologické praxi. Hlavním příznakem glaukomových onemocnění je totiž zvýšený nitrooční tlak, jehož zjištění je pro diagnostiku klíčové. Následující příspěvek prezentuje současný stav oční tonometrie a poskytuje představu o objektivní metrologické kalibraci tonometrů v blízké budoucnosti.
The paper deals with the calibration methods for machines with parallel kinematics. The procedures are based on Newton method for numerical solution of overconstrained system of nonlinear equations. The methods are applied on redundantly actuated machine with planar kinematics named ‘Sliding Star‘. The redundant measurements of relative motions in joints allow on-line calibration in real time of machine tool operation. This could significantly improve the thermal inaccuracy of machine tools with parallel mechanisms. and Obsahuje seznam literatury
The article deals with the comparison of humidity measuring instrument calibration evaluation carried out in two climatic chambers under predetermined conditions. The approach of measuring instrument calibration evaluation, including measurement uncertainties, with consideration of confidence, is shown on specific example of measurement in climatic chamber. The article is focused on the compare of two calibrations evaluation. and Príspevok sa zaoberá porovnaním vyhodnotenia kalibrácie meradla vlhkosti vykonaných v dvoch klimatických komorách za vopred stanovených podmienok. Na konkrétnom príklade merania v klimatickej komore je ukázaný prístup vyhodnotenia kalibrácie meradla vrátane neistôt merania s uvažovaním spoľahlivosti. Príspevok porovnáva vyhodnotenie dvoch kalibrácií.