Air Void Distribution of Asphalts Determined by Computed Tomography

Durability and functionality of hot mix asphalts (HMA) depend on air voids and their characteristics. The air void content of asphalt core samples could be determined by direct and indirect methods. The direct methods are destructive since they determine the air void content by decomposing the mix into its individual components. They are usually accurate but time consuming and use hazardous solvents. Because of the environmental hazards and restrictions associated with the solvents other analysis methods become really important. The computed X-ray tomography (CT) makes it possible to create a complete 3D image about the whole inner structure without any preparation or chemical fixation of the specimen. This nondestructive structure testing has a great significance at the examination of road pavement structures and could substitute a number of complex laboratory test in a more accurate and robust way. This paper demonstrates the CT method for determining the air void distribution. It shows that the proposed method can determine the air void content very accurately and gives a lot of additional information about other features by showing the distribution of the air void content along any arbitrary axis of the core sample

Tomographic reconstruction of micro-vascular network in cerebral cortical samples

Objectives The purpose of the research is the automatic processing and analysis of high-amount (nearly 1500) and high-resolution synchrotron based tomography images of mammalian cerebral cortical tissues. The objective was to acquire quantitative data allowing future blood flow modeling based on the structure of cerebral vessel network. . The brain samples were processed with histological method compatible with synchrotron x-ray microtomography. The method developed performs automated extraction of the relevant parameters of the vessel network on a standard personal computer using previously set parameters. Method The method implemented on the image series performs automatic segmentation by using determined intensity values. The procedure finds the boundary of the vessels and provides quantitative measures of the segments, and it also creates the topology of the vessel network. Results Our method produces topologically correct network of continuous, branching micro blood vessels of the sample studied. We present multiple options for the visualization of the detected vessels. The data structure also contains the statistics of each detected cross-section, in addition with the numerical quality statistics of the continuous vessel branches (e. g. vessel length or mean diameter). The algorithm resulted in highly accurate fitting at micrometer geometric resolution. ConclusionThe reconstructed vessel network is the geometrically accurate description of the blood vessels in the tissue. The data acquired could be the base of a blood vessel surface reconstruction, and by adding physiological information it could be used for simulations in normal and pathological conditions (e. g. arteriosclerosis).  The precise vascular geometry and the distance distribution provides information about the barely understood neurovascular coupling, which is the basis of such modern diagnostic and research tools as the fMRI. After analyzing samples from multiple species or brain regions the difference could be determined objectively. DOI: 10.17489/biohun/2013/1/0

BETON TŰZTERHELÉS UTÁNI SZILÁRDSÁG- ÉS MIKROSZERKEZETI VIZSGÁLATA CT-VEL

Jelen cikkben csak a beton kémiai átalakulásának hatását vizsgáljuk a beton szilárdsági és belső szövetszerkezeti jellemzőire. Ezekbe beleértendőnek érezzük a melegítés során kialakuló belső szerkezeti átalakulásokat és repedéseket is. A vizsgálatok során 7 darab betonreceptúra nyomószilárdságát, hajlító-húzószilárdságát és testszilárdságát vizsgáltuk a hőmérséklet függvényében. Az alkalmazott hőlépcsők: 20, 50, 150, 300, 400, 500, 800 °C voltak. Mivel a pórusrendszer, illetve a repedések száma a hőmérséklet emelkedésének hatására változik és ez jelentősen befolyásolja a szilárdság alakulását, ezért a szilárdsági vizsgálatainkat kiegészítettük CT vizsgálatokkal is. A vizsgálatok során igazoltuk, hogy a CT vizsgáltok egyértelműen alkalmasak a hő (tűz) terhelt betonok vizsgálatára, vagyis a szilárdság csökkenést befolyásoló anyagszerkezeti átalakulások nyomon követésére

Automatic reconstruction of brain’s micro-vascular network based onX-ray synchrotron tomography

X-ray synchrotron tomographic microscopy enables the acquisition of large amount of images with a geometric and radiometric resolution sufficient for the morphometric and topologic analysis of vascular and even of microvascular network of different organs. In this study cylindrical shaped, NiDAB labelled brain samples of a diameter of half a millimeter were imaged and analyzed with an effective pixel size of 0.38 µm. Several thousands of tomographic slices build up each reconstructed volume meaning that an automatized analysis tool is indispensable. These big data sets are processed by the developed algorithms on commercially available PCs with an automated image analysis technology in acceptable processing time. The obtained vessel segments are stored for further topological and morphometric analyses or surface/volumetric visualization purposes. These analyses contain vessel feature distribution analysis followed by 3D reconstruction. The obtained results are in accordance to the literature data.DOI: 10.17489/biohun/2015/2/0

CT alkalmazási lehetőségei az építőanyagok vizsgálatánál = Possibility of Application of CT in case of Building Materials

Az építőanyagok belső szerkezetének ismerete számunkra nagyon fontos, hiszen az anyagok tulajdonságait és tartósságát az nagymértékben befolyásolja. Az anyagok belső szerkezete sok kiegészítő információt tartalmaz, melynek vizsgálata analitikai módszerekkel csak részben lenne lehetséges. A komputertomográfiás (CT) felvételeken a vizsgálat tárgya szeletekre bontva látható. Az adatmátrixból előállított kép tulajdonképpen egy sűrűségtérkép az adott anyagokról. Ezen sűrűségképen jól kirajzolódnak a vizsgált tárgy különböző sűrűségű elemei, ezáltal különböző sűrűségű összetevői is azonosíthatóak. A szeletek egymás utáni lejátszásával gyakorlatilag bele láthatunk az anyag szerkezetébe, de három dimenzióban is ábrázolhatjuk a vizsgált anyagot. A cikk keretein belül szeretnénk áttekinteni, hogy a CT vizsgálatok hogyan lehetnek célszerűen használhatóak az építőanyagok vizsgálatai során

CT and laboratory test of the wall panels after fire load

Nowadays prefabricated elements are typically made of highstrength concrete. In case of fire load, in addition to chemical and physical changes, spalling (detachment of layers) of the concrete surface may occur. This is especially true for the high-strength concrete. Based on our previous examinations we stated that computed tomography (CT) provides a good opportunity to test the fire-damaged buildings. However, the question is whether this method can be applied even if spalling of the concrete surface is caused by fire. Fire load tests were carried out on small elements (concrete cubes and blocks) and on full-scale wall panels, then results of these tests were compared. Beside the CT tests, laboratory tests were also carried out. Results of the tests were analysed and compared and by this we validated the correctness and applicability of the CT examinations