Methodology for Designing an Optimal Test Stand for Camera Thermal Drift Measurements and Its Stability Verification.

The effects of temperature changes on cameras are realized by observing the drifts of characteristic points in the image plane. Compensation for these effects is crucial to maintain the precision of cameras applied in machine vision systems and those expected to work in environments with varying factors, including temperature changes. Generally, mathematical compensation models are built by measuring the changes in the intrinsic and extrinsic parameters under the temperature effect; however, due to the assumptions of certain factors based on the conditions of the test stand used for the measurements, errors can become apparent. In this paper, test stands for thermal image drift measurements used in other works are assessed, and a methodology to design a test stand, which can measure thermal image drifts while eliminating other external influences on the camera, is proposed. A test stand was built accordingly, and thermal image drift measurements were performed along with a measurement to verify that the test stand did eliminate external influences on the camera. The experiment was performed for various temperatures from 5 °C to 45 5 °C, and as a result, the thermal image drift measured with the designed test stand showed its maximum error of 16% during its most rapid temperature change from 25 °C to 5 °C.

Chloride Ions' Penetration of Fly Ash and Ground Granulated Blast Furnace Slags-Based Alkali-Activated Mortars.

Due to the need to reduce the CO2 emissions of mineral binders, researchers are considering the use of alkali-activated materials (AAMs) as an alternative to cementitious binders. The properties of AAMs can be more advantageous than those presented by cementitious binders, and thus they can replace Portland cement binders in some applications. Mechanical tests of AAMs are being conducted on an ongoing basis; however, durability issues related to reinforcing steel in conditions in which steel members interact with chloride ions remain unsolved. In this paper, the precursors for AAM preparations are blends of fly ash (FA) and ground granulated blast-furnace slag (GGBFS) in four slag proportions: 0%, 10%, 30% and 50% expressed as a percent of FA mass. Four alkali-activated mortars were prepared, denominated as AAM 0, AAM 10, AAM 30 and AAM 50, respectively. Their basic physical and mechanical characteristics were investigated, as were their gas transport properties. The nitrogen Cembureau method was applied to determine the permeability of the mortar. The transport properties of the chloride ions were determined using the modified NT BUILD 492 migration test. The comparison of results obtained demonstrated a positive effect of GGBFS addition in terms of an increase in bulk density, permeability, porosity and, at the same time, a reduction in chloride ion penetration. The water absorption tests also provided insight into the open pore structures of mortars. The measurements revealed a strong dependence between fluid transport through the mortars and the water absorption and initial water content of materials.

Review of Solutions for the Use of Phase Change Materials in Geopolymers.

The paper deals with the possibility of using Phase Change Materials (PCM) in concretes and geopolymer composites. The article presents the most important properties of PCM materials, their types, and their characteristics. A review of the latest research results related to their use in geopolymer materials is presented. The benefits of using PCM in building materials include the improvement of thermal comfort inside the building, and also the fact that the additive in the form of PCM reduces thermal gradients and unifies the temperature inside the concrete mix, which can reduce the risk of cracking. The paper also presents a critical analysis related to the feasibility of mass scale implementations of such composites. It was found that the use of PCM in sustainable construction is necessary and inevitable, and will bring a number of benefits, but it still requires large financial resources and time for more comprehensive research. Despite the fact that PCM materials have been known for many years, it is necessary to refine their form to very stable phases that can be used in general construction as well as to develop them in a cost-effective form. The selection of these materials should also be based on the knowledge of the matrix material.

Temperature Compensation Method for Raster Projectors used in 3D Structured Light Scanners.

Raster projectors are commonly used in many various measurement applications where active lighting is required, such as in three-dimensional structured light scanners. The effect of temperature on the raster projector, in some conditions, can lead to significant deterioration of the measurements performed with such a scanner. In this paper, the outcomes of several experiments concerning the effects of temperature on raster projectors are presented. The described research is focused on the thermal deformations of projected images caused by common thermal effects observed in projectors: those caused by the warming-up process and changes in ambient environmental temperature. A software compensation method is also presented. It is suitable for implementation in any existing measurement method that uses raster projectors. The results of performed verification experiments show that the developed compensation method can decrease the thermal drift of the projected images by up to 14 times in the ambient temperature range .

Temperature Compensation Method for Mechanical Base of 3D-Structured Light Scanners.

The effect of temperature on three-dimensional (3D) structured light scanners is a very complex issue that, under some conditions, can lead to significant deterioration of performed measurements. In this paper, we present the results of several studies concerning the effect of temperature on the mechanical base of 3D-structured light scanners. We also propose a software compensation method suitable for implementation in any existing scanner. The most significant advantage of the described method is the fact that it does not require any specialized artifact or any additional equipment, nor access to the thermal chamber. It uses a simulation of mechanical base thermal deformations and a virtual 3D measurement environment that allows for conducting virtual measurements. The results from the verification experiments show that the developed method can extend the range of temperatures in which 3D-structured light scanners can perform valid measurements by more than six-fold.

Temperature Compensation Method for Digital Cameras in 2D and 3D Measurement Applications.

This paper presents the results of several studies concerning the effect of temperature on digital cameras. Experiments were performed using three different camera models. The presented results conclusively demonstrate that the typical camera design does not adequately take into account the effect of temperature variation on the device's performance. In this regard, a modified camera design is proposed that exhibits a highly predictable behavior under varying ambient temperature and facilitates thermal compensation. A novel temperature compensation method is also proposed. This compensation model can be applied in almost every existing camera application, as it is compatible with every camera calibration model. A two-dimensional (2D) and three-dimensional (3D) application of the proposed compensation model is also described. The results of the application of the proposed compensation approach are presented herein.

Structured-Light-Based System for Shape Measurement of the Human Body in Motion.

The existing methods for measuring the shape of the human body in motion are limited in their practical application owing to immaturity, complexity, and/or high price. Therefore, we propose a method based on structured light supported by multispectral separation to achieve multidirectional and parallel acquisition. Single-frame fringe projection is employed in this method for detailed geometry reconstruction. An extended phase unwrapping method adapted for measurement of the human body is also proposed. This method utilizes local fringe parameter information to identify the optimal unwrapping path for reconstruction. Subsequently, we present a prototype 4DBODY system with a working volume of 2.0 × 1.5 × 1.5 m³, a measurement uncertainty less than 0.5 mm and an average spatial resolution of 1.0 mm for three-dimensional (3D) points. The system consists of eight directional 3D scanners functioning synchronously with an acquisition frequency of 120 Hz. The efficacy of the proposed system is demonstrated by presenting the measurement results obtained for known geometrical objects moving at various speeds as well actual human movements.

[The clinical significance of GastroPanel in diagnostics of Helicobacter pylori eradication efficiency in patients with dyspepsia with correlation of family history of gastric cancer]. / Kliniczne znaczenie GastroPanelu w diagnostyce skutecznej eradykacji Helicobacter pylori u chorych z dyspepsja w zaleznosci od rodzinnego wystepowania raka zoladka.

UNLABELLED: Gastric cancer remains a significant medical and social problem. Familial, hereditary, social, and demographic factors increase the susceptibility of subjects to cancer development, especially those infected with Helicobacter pylori (H. pylori). Apart from genetic studies, there are ongoing biochemical studies of possible practical value in assessment of the risk of gastric cancer development. The GastroPanelBiohit test, that include determination of the levels of gastrin (G-17), pepsinogen I (PGI), pepsinogen II (PGII) and antibodies IgG/IgA against H. pylori in serum, allowed us to determine whether there are any abnormal changes in the gastric mucosa. The aim of the study was to determine whether GastroPanel parameters, identified in patients with dyspeptic symptoms (with or without history of gastric cancer in first degree relatives) before and after successful eradication of H. pylori, have any clinical value, especially in gastric cancer development. MATERIAL AND METHODS: The study comprised 61 patients aged 18-56 years with symptoms of dyspepsia. In all patients, the preliminary urea breath test (UBT) for the presence of H. pylori was performed and the positive result qualified for further study. For final analysis, 42 patients were approved, who were divided into two groups: group I (a control group) - 22 patients with negative family history of gastric cancer among the relatives of first degree, group II - 20 patients with positive history of gastric cancer among the relatives of first degree. All the patients had the gastroscopy with the biopsy of gastric mucosa for the histopathological evaluation. Additionally, the GastroPanel test was performed. RESULTS: In the blood serum of the patients with H. pylori infection, the concentrations of gastrin (G-17), pepsinogen I (PGI) and pepsinogen II (PGII) did not depend on family history of gastric cancer (p > 0.05). Successful eradication of H. pylori decreases the levels of G-17, PGI and PGII (statistical significance p < 0.05), and this correlates with the histopathological changes of gastric mucosa. The patients with positive family history of gastric cancer had more intense H. pylori colonization of gastric mucosa (IV degree of insensitivity of infection in UBT; group I - 22% vs group II - 69%) as compared to the control group. After effective eradication of H. pylori, statistically significant decreases of IgG H. pylori antibodies and of the level of gastrin (p < 0.05) in blood serum were seen (in a 3 months follow up) only in the control group. CONCLUSIONS: Independently of the history of familial gastric cancer, the GastroPanelBiohit test provides important clinical data useful for diagnosis, for assessment of effectiveness of H. pylori eradication therapy and in evaluation of the degree of the inflammatory changes in gastric mucosa.

Lower body kinematics evaluation based on a multidirectional four-dimensional structured light measurement.

We report on a structured light-scanning system, the OGX|4DSCANNER, capable of capturing the surface of a human body with 2 mm spatial resolution at a 60 Hz frame-rate. The performance of modeling the human lower body dynamics is evaluated by comparing the system with the current gold standard, i.e., the VICON system. The VICON system relies on the application of reflective markers on a person's body and tracking their positions in three-dimensional space using multiple cameras [optical motion capture (OMC)]. For the purpose of validation of the 4DSCANNER, a set of "virtual" markers was extracted from the measured surface. A set of musculoskeletal models was built for three subjects based on the trajectories of real and virtual markers. Next, the corresponding models were compared in terms of joint angles, joint moments, and activity of a number of major lower body muscles. Analyses showed a good overall agreement of the modeling outcome. We conclude that the 4DSCANNER within its limitations has the potential to be used in clinical gait analysis instead of optical marker-based systems. The advantage of the 4DSCANNER over OMC solutions is that it does not burden patients with time-consuming marker application. This study demonstrates the versatility of this measurement technique.