Papers by Keyword: Calibration

Abstract: Most of types of laser distance measuring instrument cost hundreds of thousand dollars such as Atos scanner or Depth Camera that gives depth maps of space very fast. However, the handling is too complicated for non-professional users and the utilization of 3D reconstruction is very limited. This paper introduces a workflow of 3D reconstruction using a new cheaper instrument, the Microsoft Kinect. The first experiences with Microsoft Kinect v2 sensor are presented, and the ability of 3D modelling for mechanical parts is investigated. For this purpose, the point cloud on output data as well as a calibration approach are demonstrated.

Abstract: The success of gastronomic facilities is due, not in a small part, to perceived indoor atmosphere. This includes not just the interior design but also lighting and acoustics. Especially acoustics is a crucial parameter concerning the perception of the environment, but it is often neglected. The present case study investigates the usability and accuracy of acoustics simulation as applied to the retrofit project of a restaurant. The restaurant space was modelled in CAD-based modelling environment. Subsequently, acoustical simulations based on ray tracing were conducted and the simulation model was calibrated based on on-site measurements of the reverberation time. The initial simulation showed large deviations from the measured values, mainly because of uncertainties in the input data concerning the absorption properties of the used materials. Within three calibration steps, the model was revised, such that better results could be achieved. Subsequently both the initial and the calibrated models were used to develop strategies for the improvement of the acoustical performance of the space. After the implementation of the new design options in the restaurant, measurements were repeated. Again the results were compared with both the initial and the calibrated model. The results suggest that the calibrated model displayed a better performance regarding the prediction of post-retrofit circumstances when compared to the non-calibrated one.

Abstract: A low-cost data acquisition system that records information with K-type temperature probes and Dallas thermometers has been designed to carry out this research. For this, both the software and the hardware have been designed. A specimen was conducted for the thermal analysis of a homogeneous prism of a building wall. Environmental conditions have been controlled in laboratory. Four of the prism faces are thermally insulated with nearly adiabatic conditions. A source of heat is placed on one of the two uninsulated faces of the prism. This induces a temperature gradient in the wall. A sufficient set of thermometers is introduced into the prism to control the temperature gradient. The data acquisition system consists of Arduino-based controllers. The temperature at each moment can be accurately controlled with them. The data generated are saved in a file for later analysis, and to publish them on a web page is possible for real-time queries. These data allow to validate the finite element simulation model which has been carried out for this specimen. Thus, the results of the specimen have been compared with the data obtained from the model, and this allows to extrapolate the model for the thermal analysis of other façades.

Abstract: The article shows ways to improve spectral analysis of materials accuracy. It is proposed to perform image processing of a low-temperature plasma cloud during the analysis of the quantitative composition of materials. The experiment and addition of technical equipment of the spectrometer with a video surveillance system are described. An algorithm data processing is given that obtained during by testing of standard samples in various regimes in which the quantitative composition of various materials is determined This paper describes the addition of radiation control sensors to modern spectrometer. The given conditions and standard samples used to obtain the main results.

Abstract: This paper presents a high-resolution real-time 3D coordinate measurement system based on multi-angle intersection and cylindrical imaging. The measuring angle is detected by the linear camera equipped with cylindrical lenses, whose field of view is a 3D space rather than 2D plane. This camera has prominent advantages in precise coordinate measurement and dynamic position tracking due to the high resolution and outstanding frame rate of linear CCD. Each camera is a 1D angle measuring unit which confirms an angle thereby a plane passing through the light spot. With three cameras arrangement in front of the measurement field, the 3D coordinate of the light spot can be reconstructed by multi-angle intersection. An accurate and generic calibration method is introduced to calibrate this camera. The proposed calibration method is based on nonparametric ideas to find the mapping from incoming scene rays to photo-sensitive elements, and this method (black box calibration) is still effective even if the lens distortion is high and asymmetric. It is applicable to a central (single viewpoint) camera equipped with any lenses. The proposed calibration method is applied to the 3D coordinate measurement system. The coordinate measurement accuracy of the designed system is better than 0.49mm.

Abstract: A dynamic calibration method based on elliptical standard was put forward to further improve the calibration repeatability of measurement system of form measuring instruments. In this method, the radius difference of the major axis to the minor axis of elliptic contour acts as the standard value to calibrate the measuring system, and a low pass filter is used to filter the roughness, electrical noise and high frequency vibration signal which mixed into measurement data, the elliptic contour feature can be obtained accurately based on the low order harmonic properties. Compared with the traditional calibration method of flick standard, the proposed method ensure the calibration state is well consistent with the normal measuring state of the measuring system. Experimental results indicate that the calibration repeatability with 10nm can be achieved by measuring an elliptical standard. This method has been used in the calibration of measurement system of self-made ultra-precision cylindricity measuring instrument.

Abstract: One of the methods used for determining of the thermal conductivity coefficient value of building materials is the Calibrated and Guarded Hot Box method. This method is based on the principle of measuring the heat flux density that passes through the test specimen at a temperature difference between warm and cool parts of the measuring box. For measuring of thermal conductivity coefficient is at the Faculty of Civil Engineering of VŠB-TUO used the Cool Box. Measuring in Cool Box uses the same principle of measuring as Calibrated and Guarded Hot Box. For creating temperature difference during the measurements at the Cool Box is not used heat, but cold. Measurement of the thermal conductivity coefficient by a Cool Box is very complex in terms of measurement accuracy. That the resulting values as accurate as possible, it is necessary to calibrate itself refrigerated cabinets and all sensors that are used for measurements. This paper describes the principles of calibration of Cool Box and other components, which are used for measuring the thermal conductivity coefficient of selected natural building materials. Determination of the thermal insulation properties of selected materials is part of a long-term research focused on conventional and unconventional natural building materials.

Abstract: In this paper, the dynamometer for measuring the forces of the tool in FSW process was designed. The design principle of the dynamometer was adopted octagonal ring deformation to get the forces in FSW process. The design dynamometer was calibrated, the result showed the linearity and cross sensitivity of the dynamometer in allowed range, the worked reliable of the dynamometer was good. It can be used to measure the forces in FSW process.

Abstract: In the present investigation, the innovated drawing method combined with calibration process by elastic steel element of hemispheric surface part is studded. During drawing process strong meridional lengthen strength appears. That influence on necking and differential deformation distribution. In its tern, that influence on sizes and surface accuracy. Elastic element, produced of spring steel and placed along with solid punch designed to calibrate part in final drawing stage due to elastic strength happened in it. A simulation of hemispheric surface part drawing with elastic element was held. Experiment demonstrates positive influence of elastic element to decrease necking till 15-18% from started thickness. The produced part has correct strain-stress state, exact surface and minimum dispersion of dimensions.

Abstract: The paper is concerned with hypoplastic models for both coarse and fine grained soils. It concentrates on the description of models parameters and presents procedures for their evaluation based on actual laboratory tests. The sample of sand for the calibration of the hypoplastic model for coarse grained soil comes from the Třeboň basin. The sample was classified as Sa. The second sample was classified as saCl. This sample comes from the street Evropská in Prague and was used for the calibration of the hypoplastic model for fine grained soils. The classification was performed according to ČSN EN ISO 14688-2. Keywords: hypoplasticity, fine grained soils, coarse grained soils, calibration, parameters.