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Found 6319 publications

Comparison of magnesium determination methods on Hungarian soils

Csaba Centeri Renato Kalocsai G. Milics Zsolt Biró Viktoria Vona A. J. Kovács Gergely Jakab Zsolt Giczi

Publication Name: Soil and Water Research

Publication Date: 2020-01-01

Volume: 15

Issue: 3

Page Range: 173-180

Description:

Magnesium is one of the most important nutrient elements. Soils are tested for magnesium in many countries with several extractants. Each country has its own validated methods, best-suited for its soils. The current study was designed to compare different magnesium content measuring methods with 80 Hungarian samples. The magnesium content was determined by the potassium chloride (1 M KCl 1:10), Mehlich 3 and CoHex (cobalt hexamine trichloride) methods. The maximum, mean and median values resulting from all the Mg determination methods showed the following order of measured magnitude: KCl < CoHex < M3.

Open Access: Yes

DOI: 10.17221/92/2019-SWR

Experiencing the sense of presence within an educational desktop virtual reality

Borbála Berki

Publication Name: Acta Polytechnica Hungarica

Publication Date: 2020-01-01

Volume: 17

Issue: 2

Page Range: 255-265

Description:

This study examines the sense of presence in MaxWhere desktop virtual reality. Thirty-one people participated in the research. The participants spend about fifteen minutes in the virtual environment. For measuring presence, the Igroup Presence Questionnaire (IPQ) was used. The results showed that more automatic navigation positively relates to spatial presence. This research also measured the participants' level of experience with the VR software. A significant difference was found in the spatial presence and experienced realism: the more experienced users gave higher ratings on both subscales. At the same time, the involvement and the general presence scores were similar in the two groups, which is advantageous in education as the presence is positively related to the learning outcome.

Open Access: Yes

DOI: 10.12700/APH.17.2.2020.2.14

A combined fuzzy and least squares method approach for the evaluation of management questionnaires

Dalia Susniene Ojaras Purvinis Ĺaszĺo T. Ḱoczy

Publication Name: Studies in Computational Intelligence

Publication Date: 2020-01-01

Volume: 819

Issue: Unknown

Page Range: 157-165

Description:

A set of answers to questions to employees of various companies in Lithuania may refer to various positive and negative aspects of the attitudes of employees. These are called Organizational Citizenship Behavior (positive) and Counterproductive Work Behavior (negative). The components in the answers may be grouped by expert knowledge, and by statistical analysis and, according to these approaches, based on expert domain knowledge by management specialists, fuzzy signature structures describing the mutual effects of single elements in the questionnaire may be created. There are some slight differences between the two results, that indicate that expert knowledge is sometimes not objective. An additional step applying hybrid Generalised Reduced Gradient algorithm and Genetic Evolutionary Algorithm for heuristic optimization of the aggregation parameters in the Fuzzy Signatures reveals a final model according to the responses. These latter results raise some new questions, including the idea of the use of undeterministic graphs, thus resulting in Fuzzy Fuzzy Signatures. The method could be applied to other similar multicomponent vague data pools.

Open Access: Yes

DOI: 10.1007/978-3-030-16024-1_20

Investigation of swings caused by sudden wind loads during operation of an aerial ladder

Péter Horváth F. Hajdu Rajmund Kuti

Publication Name: Fme Transactions

Publication Date: 2020-01-01

Volume: 48

Issue: 2

Page Range: 351-356

Description:

In Hungary, as in other countries around the world, intervention firefighting units often use a mechanically operated aerial ladder for highaltitude rescue tasks. The safe operation of the equipment is only possible under strict safety regulations and requires a high level of expertise from the operating staff. During each intervention, extraordinary events such as sudden wind gusts can occur, which can cause extreme overload of the structural members of aerial ladders and have adverse effects on the equipment that can lead to malfunctions and-even worse-to accidents. Therefore it is important to study the consequences of external influences on aerial ladders during operation. The examination was performed on a widely used Magirus M32-L aerial ladder. The reason for choosing this type of aerial ladder is because it has a wide operating range, therefore test results can be a good starting point for other similar equipment as well. In this paper the development of our beam model and the performed finite element simulations are presented. The aim of the research is to develop a model based on geometrical measurement data that is suitable for studying the effects of wind gusts on the ladder structure. With our research, we aim to contribute to the safe operation of aerial ladders and to prevent possible accidents.

Open Access: Yes

DOI: 10.5937/FME2002351H

Purification of model dairy wastewaters by Ozone, Fenton pre-treatment and membrane filtration

Zsuzsanna László E. Lakatos Mihály Zakar Gábor Keszthelyi-Szabó Dániel Imre Farkas

Publication Name: Periodica Polytechnica Chemical Engineering

Publication Date: 2020-01-01

Volume: 64

Issue: 3

Page Range: 357-363

Description:

This study aimed to investigate the effect of ozone and Fenton-reaction as a pre-treatment before ultrafiltration of model dairy waste waters containing sodium caseinate. Filtration resistances and pollutant retentions were determined and compared. It was found, that both pre-treatment increased the retention, achieving almost 100 % pollutant elimination efficiency after short term pre-oxidation. The effect of Fe-ion concentration on Fenton pretreatment efficiency also was examined, and it was found that higher concentration resulted in decreased filtration resistances, revealing that coagulation-flocculation effect of reactants has dominant role in the protein separation efficiency. The presence of lactose also affects the pollutant removal efficiency, it promotes fouling in presence of Fenton reagents.

Open Access: Yes

DOI: 10.3311/PPch.15046

Automated synthesis of process-networks by the integration of P-graph with process simulation

Ákos Orosz Raymond R. Tan Jean Pimentel Ferenc Friedler

Publication Name: Chemical Engineering Transactions

Publication Date: 2020-01-01

Volume: 81

Issue: Unknown

Page Range: 1171-1176

Description:

Chemical process simulation has become one of the most important tools for the analysis of process networks. The simulation software currently available are not capable of automatically generating the process structure, the designer must provide it as an input for the simulation. This limits the contribution of simulation to the latter stages of design after the structure has been clearly defined. Since the P-graph methodology was originally conceived to generate process structures systematically, it can be used to produce the topology of the problem automatically based on rigorous combinatorial axioms and algorithms. In this work, the properties of two P-graph algorithms are exploited to automatically generate alternative structures in a commercial simulator, conferring the latter an improved capacity to assist during the early stage of design. Initially, the maximal structure generation (MSG) algorithm is employed to identify a rigorous superstructure from the initial set of plausible operating units. The solution structure generation (SSG) algorithm is then used to enumerate all combinatorially feasible processes included in the superstructure. Each process structure is individually exported to Aspen Plus®, where rigorous models are used to simulate its performance. A set of alternative processes ranked by their economic performance can be generated. This integrated methodology is employed in a case study for producing methyl lactate from methanol and lactic acid. This work demonstrates that integration of P-graph with rigorous simulation constitutes an enhanced tool for process synthesis that automates the generation of process alternatives, providing useful information and additional insight of the synthesis problem.

Open Access: Yes

DOI: 10.3303/CET2081196

Measuring global value chains by input-output tables

Koppány Krisztián Gáspár Tamás

Publication Name: Statisztikai Szemle

Publication Date: 2020-01-01

Volume: 98

Issue: 9

Page Range: 1035-1065

Description:

No description provided

Open Access: Yes

DOI: 10.20311/stat2020.9.hu1035

Water-assisted production of polypropylene/boehmite composites

László Lendvai

Publication Name: Periodica Polytechnica Mechanical Engineering

Publication Date: 2020-01-01

Volume: 64

Issue: 2

Page Range: 128-135

Description:

In this study polypropylene (PP) matrix-based boehmite alumina (BA) reinforced composites were prepared batchwise in an internal mixer. BA particles up to 10 wt.% were incorporated by 1. traditional melt mixing and 2. in a novel, Water-Assisted (WA) way, called fast evaporation mixing, during which BA was dispersed in PP with the use of an aqueous carrier medium. The WA way with pure water as medium proved to be ineffective because of the presence of the Leidenfrost effect. Therefore, an additional agent, carboxymethyl cellulose (CMC) was used to increase the boiling temperature of the water. Mechanical, morphological and thermal properties of the composites were determined. Scanning electron microscopy images revealed a partially dispersed structure of BA within the PP matrix in all cases, where aggregates and dispersed particles were identified as well. The size of the agglomerates observed was the smallest when BA was incorporated by being dispersed in water/CMC firstly. The mechanical tests results indicated that the reinforcing effect of BA was also most prominent in this case. However, CMC had an opposite effect on PP, than BA thus reducing the overall enhancement in mechanical properties. Differential scanning calorimetry showed an increase in the crystallinity ratio of PP with increasing BA content, which indicates a nucleating effect of BA.

Open Access: Yes

DOI: 10.3311/PPME.13981

Hungarian Territorial Changes and Nationality Issues Following World War I

Mónika Ganczer

Publication Name: Hungarian Yearbook of International Law and European Law

Publication Date: 2020-01-01

Volume: 8

Issue: 1

Page Range: 120-135

Description:

In the aftermath of World War I, Hungary had to relinquish approximately two-thirds of its former territory and over half of its population under the terms of the Trianon Peace Treaty of 4 June 1920. This inevitably brought about a change in the nationality of persons pertaining to territories transferred to other states. However, the interpretation and implementation of articles concerning nationality were highly ambiguous. For example, the rights of citizenship in a commune, the so-called pertinenza, was not defined in the peace treaty, although the determination of affected persons and beneficiaries of the right of option was explicitly based on that particular criterion. Hence, the fate of these individuals largely depended on the domestic legal regulation and the subjective treaty interpretations of successor states. The application of treaty provisions was not always in conformity with the text, which sometimes proved advantageous, other times disadvantageous for the affected persons. This study seeks to explore the theoretical background, the past and present interpretation, the practical application and the judicial treatment of articles concerning nationality in the Trianon Peace Treaty. The paper also exposes the major problems and shortcomings of the Treaty and makes suggestions for an appropriate wording and adequate interpretation of relevant treaty provisions. Furthermore, in order to provide a full picture of how territorial changes following World War I affected the nationality of millions of individuals, the study takes into consideration other contemporary international instruments with a bearing on the change of nationality or its consequences.

Open Access: Yes

DOI: 10.5553/HYIEL/266627012020008001008