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Open access

Bálint Levente Tarcsay, Éva Mihálykó-Orbán and Csaba Mihálykó

Abstract

Safety regulations demand the elimination of random mistakes and the reliable operation of production units. However, the control and maintenance of batch and semi-continuous processes haalways been difficult. In this paper, a way of preventing malfunctions in batch and semi-continuous processes is presented by using appropriately designed buffer tanks. A stochastic model was investigated in which batch and continuous subsystems were linked by an intermediate storage tank. The main concern was the reliability of the system. Reliable operation was defined as neither the exhaustion of raw materials nor the excessive accumulation of them. The counting processes that describe the random batch-input and random batch-output processes are supposed to be independent homogeneous Poisson processes with different rates. By introducing a function that describes the material in storage, reliable operation is defined as when this function satisfies two inequalities for a time interval of any duration. By applying probabilistic methods, an integral equation is set up for the the reliability. Nevertheless, its analytical solution cannot be determined, hence the values according to a Monte Carlo simulation are approximated. By applying this method, a link could be identified between the necessary initial buffer and tank capacities that belong to a reliability level. Economic investigations were conducted to help determine the optimal initial buffer and tank capacities that satisfy the appointed reliability level.

Open access

Tomasz Ireneusz Jedliński, Jacek Buśkiewicz and Paweł Fritzkowski

Abstract

Apart from the strength requirements, modern lighting pole designs have to meet a number of safety requirements in the event of collisions. The paper compares the experimental tests performed at the collision test track according to EN 12767 with the results of the numerical analysis carried out in Ansys LS-DYNA. The objective of the work is to prepare a new structure of a thin-walled lighting pole of steel which minimizes absorption of the kinetic energy of the vehicle and, simultaneously, its production costs are comparable to those of a standard pole. The tests were carried out at an impact speed of 100 km/h.

Open access

Ildikó Szedljak, Anikó Kovács, Gabriella Kun-Farkas, Botond Bernhardt, Szabina Králik and Katalin Szántai-Kőhegyi

Abstract

Red lentils are a very important raw material in the food industry due to their high protein content and high level of health-promoting components. The nutritive value of red lentils is the most important attribute from a research point of view; it can be increased by germination, soaking as well as physical and biochemical processes. The antinutritive materials are reduced or denatured by the germination process and indigestible components become available to the human body. Heat treatment was applied to achieve different temperatures and increase the microbiological stability of germinating samples. The effect of heat treatment on the amounts of certain components and the activity of oxidative enzymes was tested during our experiments; the nutritional characteristics (water-soluble total polyphenol content (WSTPC), water-soluble protein content (WSPC), water-soluble antioxidant capacity, in addition to peroxidase and polyphenol oxidase enzyme activities) of different treatments in red lentil samples were monitored. The WSTPC in our samples ranged from 0.726 mg Gallic Acid Equivalent GAE/g DW (DW being dry weight) to 1.089 mg GAE/g DW, and the WSPC varied from 19.078 g / 100g DW to 29.692 g / 100 g DW. Results showed that germination led to an increase in the WSTPC and WSPC. The peroxidase enzyme activity also exhibited an increase during germination which could result in deepening of the colour of the finished products. Germination resulted in the water-soluble antioxidant capacity of red lentil samples decreasing.

Open access

Mathias Flansbjer and Jan Erik Lindqvist

Abstract

This project focused on how the cracking process in concrete is influenced by both the micro and meso structures of concrete. The aim was to increase knowledge pertaining to the effect of critical parameters on the cracking process and how this is related to the material’s macroscopic properties. A methodology based on the combination of different experimental methods and measuring techniques at different scales was developed. Crack propagation during tensile loading of small-scale specimens in a tensile stage was monitored by means of Digital Image Correlation (DIC) and Acoustic Emission (AE). After testing, crack patterns were studied using fluorescence microscopy.

Open access

Katalin Kóczán-Manninger and Katalin Badak-Kerti

Abstract

Bread samples were made using flour mixes of Triticum monococcum (Tr. monococcum) and Triticum spelta (Tr. spelta). They were tested for their rheological behaviour over the first 3 days of storage at room temperature, and for their characteristics based on a Hungarian Standard. Parameters were set such as the volume of the baked product, baking loss, crumb characteristics and elasticity of crumbs. The behaviour of flour from einkorn wheat is different to that of Tr. spelta. The properties of the tested flour mixes measured by a farinograph show that Tr. spelta produces an acceptable dough, on the other hand, the dough of Tr. monococcum develops quickly but is very unstable so weakens within minutes of being kneaded. This also suggests that doughs composed of einkorn wheat flour require a different type of kneading than those of Tr. spelta (or Tr. aestivum, also referred to as common wheat) flours. Breads composed of Tr. spelta were comparable with those made with Tr. aestivum, the crumb elasticity was above 90 % on the day of baking, which indicates high quality. The Tr. monococcum breads, however, were of low grade: the volume of the breads decreased by increasing the ratio of Tr. monococcum to Tr. spelta and the elasticity reduced to unacceptable levels (less than 60 %). It should be mentioned that the grading was based on breads made purely from Tr. aestivum flours.

Open access

Sándor Nagy

Abstract

To correlate the dipole moment and density dependence of the initial magnetic susceptibility on the basis of the former related theories and the probability analysis of chain formation, physically based analytical correlation equation was derived. After the local magnetic field strength and the chaining probability between two particle have been determined the chain and particle distributions came from the geometric distribution. The initial magnetic susceptibility was resulted from the summation of Langevin initial susceptibility of k-length chains. Two particles were considered in a chain if the interaction energy between them was below a certain limit. By varying slightly this energy limit around 70–75 % good agreement has been obtained between the simulation and theoretical data. Monte Carlo simulations were used to calculate the initial magnetic susceptibility of dipolar hard sphere system at different dipole moments and densities.

Open access

Tobias Danner and Harald Justnes

Abstract

Calcined clays are gaining increasing interest as future supplementary cementitious materials for the production of blended cements. Besides the mineralogy, the right production conditions can affect the pozzolanic activity of calcined clays. In this paper, the pozzolanic reactivity of two calcined natural clays in dependence of burning temperature, residence time in the furnace, cooling conditions and particle size of the final product is investigated. The highest pozzolanic reactivity was found at calcination temperatures between 600 and 800°C. While different cooling conditions had no identified effect on reactivity, decreased particle size and residence time increased the reactivity.

Open access

Kimmo Jalonen, Joonas Tulonen and Anssi Laaksonen

Abstract

Imposed and restrained deformations cause stresses in continuous concrete bridges, and in analyses of the superstructure these stresses are usually reduced to some degree due to creep and cracking of concrete. This study examines cracking and redistribution of stresses in a bridge superstructure under the loads and load combinations used in the original bridge design. The subject of this study is a three-span post-tensioned continuous concrete cantilever beam bridge. The bridge was analysed with non-linear calculation utilising the general force method and moment-curvature relationships. The analysis yielded the bending stiffness of the post-tensioned bridge superstructure as a function of bridge length under different loads. It was discovered that the secondary moment from prestressing force increased as the bending stiffness of the central span decreased due to cracking under external loads, which is not normally considered in design. The bending moment effects of linear temperature difference and support settlement decreased as expected as the superstructure bending stiffness decreased. The analysis provided new information on the effects of secondary moment from the prestressing force and on the difference between the cracked state and the linear elastic analysis of the concrete bridge superstructure.

Open access

Andres Belda Revert, Klaartje De Weerdt, Ulla Hjorth Jakobsen and Mette Rica Geiker

Abstract

The paper summarizes preliminary results on characterization of the microstructure and phase assemblage of mortar and concrete samples containing Portland and Portland-fly ash cement carbonated at either natural conditions, 60% RH and 1% CO2, 90% RH and 5% CO2 or 60% RH and 100% CO2. Different characterization techniques were used: thermogravimetric analysis to study the solid phases, SEM-EDS point analysis to investigate the chemical composition of the solid phases, optical microscopy to investigate the microstructure, and cold water extraction to characterize the chemical composition of the pore solution. The combined results on microstructure and phase assemblage indicate that carbonation up to 5% CO2 appears representative for natural carbonation. Pore solution analysis revealed similar trends for the three accelerated carbonation conditions.

Open access

Erzsébet Bognár, Gabriella Hellner, Andrea Radnóti, László Somogyi and Zsolt Kemény

Abstract

Glycidyl esters are foodborne contaminants formed during the production of fats and oils, especially during the deodorization of palm oil. The hydrolyzed free form of glycidol has been categorized as probably carcinogenic to humans by the World Health Organization’s International Agency for Research on Cancer. The aim of this research was to study the formation of glycidyl esters during the lab-scale deodorization of the three most widely produced seed oils in the world (sunflower, rapeseed and soybean). The effects of two independent factors – temperature and residence time – were analyzed by a 32 full factorial experimental design and evaluated by response surface methodology. In accordance with findings in the literature, the greatest amount of glycidyl esters was formed in the soybean oil matrix. For all three oils, the effects of both residence time and temperature were significant, while the latter was more so. To reduce the formation of glycidyl esters, milder deodorization is required, which is limited because of the purposes sought by the thermal operation and removal of volatile minor components and contaminants.