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Found 6674 publications

Numerical investigation on flexural buckling behavior of hot-rolled steel columns at elevated temperatures

Samer Nemer F. Papp

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 918-927

Description:

In this paper, a numerical investigation on the global buckling capacity of the axially compressed steel columns with hot-rolled I cross-section at elevated temperatures is presented. Geometrically and materially non-linear finite element model and the ABAQUS software were used to determine the buckling resistance. The numerical ABAQUS model was validated using experimental results available in the literature, and then the validated numerical model was used to generate a database of load-carrying capacity. The parametric study covered three different cross-section classes (class 1, 2 and 3), ten different non-dimensional slenderness ̄λ = 0.5, 0.6, 0.7, 0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.0), three different temperatures (400°C, 500°C, 600°C), and two stress-strain constitutive relations including (the nonlinear material model adopted in the European guidance for structural fire design EN1993-1-2, and a Bilinear material model), with and without residual stress. The influence of the model parameters on the load capacity of steel columns at elevated temperatures was evaluated. The results of the parametric study were compared with the results of the simplified calculation model presented in EN1993-1-2.

Open Access: Yes

DOI: 10.3311/PPci.17799

Nonlinear moving horizon predictive control of ground vehicles

Gyorgy Max Bela Lantos

Publication Name: Cinti 2014 15th IEEE International Symposium on Computational Intelligence and Informatics Proceedings

Publication Date: 2014-01-30

Volume: Unknown

Issue: Unknown

Page Range: 421-426

Description:

The paper deals with the approximately time-optimal control of automatically driven cars modeled with gear shift as discrete control input beside the continuous ones in a path between two path boundaries. The path boundaries are defined by their corner points that may be the result of image processing in real time or prescribed in advance. The path is divided into sections for which separate optimum control problems are solved in a nonlinear moving horizon predictive control (NMHPC) fashion increasing the semi-online character of the approach. In each section the problem can be formulated as a mixed-integer optimal control problem (MIOCP). The resulting MIOCP is solved by reformulating it to static mixed-integer nonlinear program (MINLP) using time discretization and direct multiple shooting method. Non-commercial open software packages are applied that substantially use the gradients of the objective function and the Jacobians of the constraints exploiting sparsity. The elaborated method can be applied both for combustion engine and electric driven cars. It can also form the basis to generate an offline database of a central general collision avoidance system (CAS) for varying path parameters on a grid which can further support real time applications.

Open Access: Yes

DOI: 10.1109/CINTI.2014.7028712

Logic testing of CMOS structures

Jozsef Sziray

Publication Name: Iccc 2004 Second IEEE International Conference on Computational Cybernetics Proceedings

Publication Date: 2004-12-01

Volume: Unknown

Issue: Unknown

Page Range: 59-64

Description:

The paper presents a test calculation principle which serves for producing tests of switch-level logic faults in CMOS digital circuits. The considered fault model includes stuck-at-0/1 logic faults on the connecting lines, as well as switch faults in the transistors. Both single and multiple faults are included. The transistor faults manifest themselves in stuck open (open circuit) and stuck short (short circuit) behavior. In this paper only combinational logic circuits are taken into consideration. The calculation principle is comparatively simple. It is based only on successive line-value justification, and it yields an opportunity to be realized by an efficient computer program. ©2004 IEEE.

Open Access: Yes

DOI: DOI not available

Development of atomic beam probe for tokamaks

M. Berta G. Anda I. G. Kiss J. Havlíček Sz Tulipán P. Hacek M. Aradi Cs Buday G. Veres S. Zoletnik A. Bencze

Publication Name: Fusion Engineering and Design

Publication Date: 2013-11-01

Volume: 88

Issue: 11

Page Range: 2875-2880

Description:

The concept and development of a new detection method for light alkali ions stemming from diagnostic beams installed on medium size tokamak is described. The method allows us the simultaneous measurement of plasma density fluctuations and fast variations in poloidal magnetic field, therefore one can infer the fast changes in edge plasma current. The concept has been worked out and the whole design process has been done at Wigner RCP. The test detector with appropriate mechanics and electronics is already installed on COMPASS tokamak. General ion trajectory calculation code (ABPIons) has also been developed. Detailed calculations show the possibility of reconstruction of edge plasma current density profile changes with high temporal resolution, and the possibility of density profile reconstruction with better spatial resolution compared to standard Li-BES measurement, this is important for pedestal studies. © 2013 Elsevier B.V.

Open Access: Yes

DOI: 10.1016/j.fusengdes.2013.05.064

Optimal plastic analysis and design of pile foundations under reliable conditions

R. M. Movahedi Sarah Khaleel Ibrahim

Publication Name: Periodica Polytechnica Civil Engineering

Publication Date: 2021-07-13

Volume: 65

Issue: 3

Page Range: 761-767

Description:

In this research, in order to evaluate the plastic limit load and also plastic design parameters of the long pile foundations subjected to horizontal loads, shakedown method is applied. In carrying out shakedown analysis and design methods, large plastic deformations and residual displacements could develop in the pile foundation which might lead to the failure of the structure. For this reason, complementary strain energy of residual forces proposed as a limit condition to control the plastic deformation of the pile structure. Furthermore, considering the uncertainties (strength, manufacturing, geometry) the limit conditions on the complementary strain energy of residual forces are assumed randomly and the reliability condition was formed by the use of the strict reliability index. The influence of the limit conditions on the plastic limit load and design parameters of the long pile in cohesionless soil subjected to lateral load were investigated and limit curves for shakedown load factors are presented. The numerical results show that the probabilistic given limit conditions on the complementary strain energy of residual forces have significant influence on the load bearing limit and the design parameters of pile foundations. The formulations of the reliability based problems lead to mathematical programming which were carried out by the use of non-linear algorithm.

Open Access: Yes

DOI: 10.3311/PPci.17402

Exploring the rosmarinic acid profile of dark chocolate fortified with freeze-dried lemon balm extract using conventional and non-conventional extraction techniques

E. Lakatos V. Kapcsándi Rita Székelyhidi Beatrix Sik Zsolt Ajtony

Publication Name: Lwt

Publication Date: 2021-07-01

Volume: 147

Issue: Unknown

Page Range: Unknown

Description:

The present study evaluated the feasibility of the fortification of dark chocolate with a freeze-dried lemon balm extract rich in rosmarinic acid (RA). Given the food matrix used, it was necessary to develop an analytical and extraction method for RA determination in fortified chocolate. A simple and efficient reversed-phase high-performance liquid chromatography method (RP-HPLC) has been developed for the estimation of RA in dark chocolate. The validity of the method was demonstrated by evaluating the system suitability, linearity, precision, accuracy, the limit of detection, and limit of quantification. The extraction of RA from chocolate was optimized using maceration with shaking (MACS) and microwave-assisted extraction (MAE). The experimental conditions, namely solvent type and extraction time, were optimized using the one-factor-at-a-time methodology. Under the optimized conditions, the proposed method showed good recovery within 95% and acceptable reproducibility with intra- and inter-day relative standard deviations of <2.3%. The method was linear from 5 to 800 μg/mL with a determination coefficient of 1.000. Moreover, the functional chocolate showed a homogeneous active ingredient distribution and retained its RA amount since no significant difference was observed during storage. Overall, the present method was successfully applied to determine RA content in fortified chocolate.

Open Access: Yes

DOI: 10.1016/j.lwt.2021.111520

A hybrid discrete bacterial memetic algorithm with simulated annealing for optimization of the flow shop scheduling problem

Olivér Hornyák Károly Nehéz Anita Agárdi László T. Kóczy

Publication Name: Symmetry

Publication Date: 2021-07-01

Volume: 13

Issue: 7

Page Range: Unknown

Description:

This paper deals with the flow shop scheduling problem. To find the optimal solution is an NP-hard problem. The paper reviews some algorithms from the literature and applies a benchmark dataset to evaluate their efficiency. In this research work, the discrete bacterial memetic evolutionary algorithm (DBMEA) as a global searcher was investigated. The proposed algorithm improves the local search by applying the simulated annealing algorithm (SA). This paper presents the experimental results of solving the no-idle flow shop scheduling problem. To compare the proposed algorithm with other researchers’ work, a benchmark problem set was used. The calculated makespan times were compared against the best-known solutions in the literature. The proposed hybrid algorithm has provided better results than methods using genetic algorithm variants, thus it is a major improvement for the memetic algorithm family solving production scheduling problems.

Open Access: Yes

DOI: 10.3390/sym13071131

The recent advances of near-infrared spectroscopy in dairy production—a review

Tamás Tóth George Bázár Zoltan Kovacs Haruna Gado Yakubu

Publication Name: Critical Reviews in Food Science and Nutrition

Publication Date: 2022-01-01

Volume: 62

Issue: 3

Page Range: 810-831

Description:

One of the major issues confronting the dairy industry is the efficient evaluation of the quality of feed, milk and dairy products. Over the years, the use of rapid analytical methods in the dairy industry has become imperative. This is because of the documented evidence of adulteration, microbial contamination and the influence of feed on the quality of milk and dairy products. Because of the delays involved in the use of wet chemistry methods during the evaluation of these products, rapid analytical techniques such as near-infrared spectroscopy (NIRS) has gained prominence and proven to be an efficient tool, providing instant results. The technique is rapid, nondestructive, precise and cost-effective, compared with other laboratory techniques. Handheld NIRS devices are easily used on the farm to perform quality control measures on an incoming feed from suppliers, during feed preparation, milking and processing of cheese, butter and yoghurt. This ensures that quality feed, milk and other dairy products are obtained. This review considers research articles published in reputable journals which explored the possible application of NIRS in the dairy industry. Emphasis was on what quality parameters were easily measured with NIRS, and the limitations in some instances.

Open Access: Yes

DOI: 10.1080/10408398.2020.1829540

Ion exchange with copper-tetraamine on naa (Lta) type synthesised zeolite

Pál Szakál Renato Kalocsai Éva Szalka Tamás Szakál Endre Andor Tóth Bálint Szüle Tamás Korim

Publication Name: Nova Biotechnologica Et Chimica

Publication Date: 2021-06-23

Volume: 20

Issue: 1

Page Range: Unknown

Description:

A crop growing in the right quantity and quality can only be secured if nutrients are provided in an adequate quantity and available form. Copper (Cu) has primary importance among microelements in growing winter wheat. Lack of Cu hinders nitrogen uptake by plants. Therefore, increasing bioavailability is important in crop production. It has been conducted successful foliar fertilisation experiments with Tetraamminecopper(II) sulphate for several years. The efficiency of the applied compound was enhanced by the application of a retarded nutrient-supply. To secure retardation, ion exchange was carried out in NaA type synthesized zeolite with Tetraamminecopper(II) sulphate. Structure of Tetraamminecopper(II) sulphate, and zeolite ion-exchanged by copper-tetraamine was analysed with a derivatograph and X-ray diffraction. Derivatograph analyses revealed heat stability. X-ray diffraction analyses revealed that copper-tetramine ions exchanged a significant part of the sodium ions of zeolite in ion exchange.

Open Access: Yes

DOI: 10.36547/nbc.886