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Impact of calcium ions leaching caused by biogenic acid attack on durability of cement composites
No full textLeaching of calcium ions increases the porosity of cement-based materials, consequently resulting in a negative effect on durability since it provides an entry for aggressive harmful ions, causing corrosion of concrete. Sulphuric acid corrosion of concrete can be caused due to attack of aggressive media naturally existing in the environment. Another possibility of corrosion formation is biogenic acid effect through the agency of microorganisms.
The paper is focused on the investigation of the influence of biogenic acid attack on the cement composites affected with bacteria Acidithiobacillus thiooxidans. The concrete specimens with 95% wt. addition of antimicrobial activated granulated blast furnace slag as durability increasing factor as well as without any addition were studied. The experiments proceeded during the nine 7-day cycles. The pH values and chemical composition of leachates were measured and evaluated after each cycle. The higher resistance of concrete samples with the addition of 95% wt. of antimicrobial activated granulated blast furnace slag to the aggressive environment was confirmed. The leaching of calcium ions of concrete sample affected with bacteria Acidithiobacillus thiooxidans was 1.13 times lower (736.6 mg/L of leachate) for concrete sample with antimicrobial activated granulated blast furnace slag addition comparing to concrete sample of ordinary CEM I Portland cement without any additives (832.0 mg/L of leachate)
The machine drawings of Hans Hammer in the context of the contemporary machine representations
No full textThe first known drawings of machines can be found in warfare-themed manuscripts. The oldest of them dates back to the 14th century, but their proliferation took place in the 15th century. During the century an almost standardized drawing style, vocabulary was developed, which also survived throughout the Renaissance.
Compared to the relatively high number of the survived warfare-related manuscripts that included drawings (their number is above 50), the representation of machines for civil usage is very rare throughout the century, even though the architectural drawings also proliferated during this century, and they also introduced a distinct representation style.
The survived portfolio of the Strasbourg master builder Hans Hammer lies at the intersection of this two disciplines: it includes both machine and architectural drawings in a large number. Given the occupation of the master, it can safely assumed that in contrast to those found in the majority of the contemporary machine drawings, his machines served civil purposes.
In this article the following questions are discussed: how do Hans Hammer’s machine drawings fit in the corpus of the contemporary machine drawings both by drawing style and function; and with which manuscripts can a direct connection be made
Fast Iterative Solvers for Large Compressed-Sparse Row Linear Systems on Graphics Processing Unit
No full textEngineering problems involve the solution of large sparse linear systems, and require therefore fast and high performance algorithms for algebra operations such as dot product, and matrix-vector multiplication. During the last decade, graphics processing units have been widely used. In this paper, linear algebra operations on graphics processing unit for single and double precision (with real and complex arithmetic) are analyzed in order to make iterative Krylov algorithms efficient compared to central processing units implementation. The performance of the proposed method is evaluated for the Laplace and the Helmholtz equations. Numerical experiments clearly show the robustness and effectiveness of the graphics processing unit tuned algorithms for compressed-sparse row data storage
Serial Delay-Line Readout for Position Sensitive Neutron Beam Monitor
No full textThe intensity of neutron beams is measured by neutron beam monitor detector at research reactors, in order to allow normalization of neutron scattering data. A two dimensional position sensitive neutron beam monitor has been developed, able to measure the distribution of beam intensity in its cross-section. The neutron adsorption efficiency of these monitor detectors are low enough to minimize the intensity loss, but high enough to provide low statistical error. Since the number of detected events is not too high, the dead time is not crucial for these detectors. A novel readout method has been developed that slightly increases the dead time but eventuates a robust, simple and flexible system. This new method relies on the serial connection of the delay-lines, minimizing the number of analogue signals. Two or three analogue signal outputs are enough to reconstruct the two-dimensional intensity matrix. Combining this new method with a comprehensive acquisition on the primary signals, the quality parameters of the detectors are also improved. Design and measurement results at the Budapest Research Reactor are presented
Pedestrian’s Level of Service on Tramline Platforms in Budapest
No full textThe article aims at presenting the analysis of pedestrian behavior at transport stops, with special focus on tram platforms. The most important characteristics of a platform are length and width. Determining the level of service is also applied in international context on the basis of which the area is measurable. This article aims to show these briefly, and provides a recommendation for domestic application while incorporating the most characteristic features. On the basis of the measurement and micro-simulation, recommendation can be made for the level of service. The method of improving the quality of service is shown through the enlargement of the platform’s effective area
Application of information technologies and principles of lean production for efficiency improvement of machine building enterprises
No full textThe head-line of the article is advisability to combine information technologies and principles of lean production in activity of machine building enterprises to ensure efficiency improvement. The article reviews enterprise resource planning systems and the lean production conceptions: their development and construction basis, main advantages and weaknesses
Edge finite element method in case of high frequency simulations
No full textThe paper deals with high frequency simulations with edge finite element method realized with PETSc functions. The weak formulations of the high frequency simulations are derived from Maxwell’s equations in frequency domain. To reduce the calculation time, the finite element method was implemented in PETSc environment. The realized simulation environments were validated with simple examples, which analytically can be calculated
