Search results for "materiaalitutkimus"

Effective elastic properties of biocomposites using 3D computational homogenization and X-ray microcomputed tomography

2021

A 3D computational homogenization method based on X-ray microcomputed tomography (μCT) was proposed and implemented to investigate how the fiber weight fraction, orthotropy and orientation distribution affect the effective elastic properties of regenerated cellulose fiber-polylactic acid (PLA) biocomposites. Three-dimensional microstructures reconstructed by means of the X-ray μCT were used as the representative volume elements (RVEs) and incorporated into the finite element solver within the computational homogenization framework. The present method used Euclidean bipartite matching technique so as to eliminate the generation of artificial periodic boundaries and use the in-situ solution d…

Instrumentation for time-of-flight elastic recoil detection analysis

2016

Time-of-flight elastic recoil detection is an ion beam based method to analyze the elemental composition of thin film samples at different depths. In order to improve the mass resolution and to enable kinematic correction a position sensitive gas ionization chamber energy detector was constructed. This detector along with pre-existing timing detectors were connected to a modern fully digitizing data acquisition setup. This thesis describes the design of these instruments, including all aspects from the mechanical design of the gas ionization detector to the algorithm and software development of the digitizing acquisition setup. The performance of the system has been studied with measurements …

The effect of steric hindrance on the packing of elongated objects

2016

Fibres of various materials can be deposited to form planar mats of fibres. These kinds of structures have gained substantial attention owing to their direct relation to both large industrial fields, such as paper and nonwovens, and biological structures, such as natural networks of fibrin, actin and collagen. In addition, similar structures are important in new emerging fields such as flexible electronics and tissue engineering. The physical properties of these structures are directly related to the connectivity of the network, thus a thorough understanding of the contact formation of the system is of great importance from both a scientific viewpoint as well as for its application in the e…

Discrete element model for viscoelastic materials with brittle fracture : applications on glacier dynamics

2017

Kuituverkostojen yksityiskohtainen analysointi korkean resoluution kolmiulotteisista kuvista

2009

Luonnontieteellisin analyysimenetelmin tunnistettu Akseli Gallen-Kallelan väripaletti

2020

Artikkeli on kokonaisuudessaan ensimmäinen laatuaan Suomessa ja se esittelee tutkimuksen tuloksia koskien Akseli Gallen-Kallelan käyttämiä väriaineita. Tutkimusaineisto on läpileikkaus taiteilijan taiteellisesta tuotannosta vuosilta 1880–1929.  Se koostuu 265:stä maalauksesta ja 83:sta öljy- ja temperavärituubista. Tutkimuksessa käytetyt analyysimentelmät ovat ainetta tuhoamattomia luonnontieteellisiä analyysimenetelmiä: energiadispersiivinen röntgenfluoresenssi spektroskopia (EDXRF) ja polarisaatiomikroskopia (PLM).
  
 Avainsanat: Akseli Gallen-Kallela, taiteilijatarvike, väriaine, pigmentti, taiteen materiaalitutkimus, EDXRF, polarisaatiomikroskopia.

Observations on the Painting Technique and Materials Used in the Painting of Lake View, by Akseli Gallen-Kallela

2021

Calibration of the bone mineral density scale on X-ray microtomography

2016

The microstructure of bentonite clay

2018

Bentonite is a common clay having many applications. One of them will be in the spent nuclear fuel repository, as a buffer material between host rock and the canisters containing the radioactive waste. This application has high requirements for the material used, ranging from, among others, appropriate mechanical properties, chemical stability, fine porous structure to sufficient hydraulic conductivity. The material should maintain its properties over time as the life span of the repository is hundreds of thousands years. The aim of this thesis was to investigate the structure of bentonite clay in a condition similar to expected in the repository. The research focused mainly on the pore str…

Analysis of microtomographic images of porous heterogeneous materials

2015

In this work, we study the phases of image processing chain of microtomographic imag- ing in order to obtain reliable results while optimizing the time spent on denoising and segmentation. We consider that the decisions made at the early phases of the processing chain are most important and the selection made there essentially determine the overall quality of imaging process. We also compare here various denoising method qualita- tively, however, we think that the pure noise removal ability is not the only requirement for noise removal in microtomographic images. By proper denoising we can affect selec- tion of segmentation methods and, thus, also the quality of the analysis. Additionally, …