Numerical method to determine the elastic curve of simply supported beams of variable cross-section

István Bíró,Livija Cveticanin,Péter Szuchy 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.6

In this paper a new numerical method to determine the elastic curve of the simply supported beams of variable cross-section is demonstrated. In general case it needs to solve linear or small nonlinear second order differential equations with prescribed boundary conditions. For numerical solution the initial values of the slope and the deflection of the end cross-section of the beam is necessary. For obtaining the initial values a lively procedure is developed: it is a special application of the shooting method because boundary value problems can be transformed into initial value problems. As a result of these transformations the initial values of the differential equations are obtained with high accuracy. Procedure is applied for calculating of elastic curve of a simply supported beam of variable cross-section. Results of these numerical procedures, analytical solution of the linearized version and finite element method are compared. It is proved that the suggested procedure yields technically accurate results.

Procedures for determination of elastic curve of simply and multiple supported beams

István Bíró,Livija Cveticanin 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.1

In this paper two procedures for determination of the elastic curve of the simply and multiple supported beams are developed. Determination of the elastic curve is complex as it requires to solve a strong nonlinear differential equation with given boundary conditions. For numerical solution the initial guess of the slope at the end of the beam is necessary. Two procedures for obtaining of the initial guess are developed: one, based on transformation of the supported beam into a clamped-free one, and second, on the linearization of the problem. Procedures are applied for calculating of elastic curve of a simply supported beam and a beam with three supports. Obtained results are compared. Advantages and disadvantages of both methods are discussed. It is proved that both suggested procedures give us technically accurate results.

Extension of silo discharge model based on discrete element method

István Oldal,Ferenc Safranyik 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.9

Silos are containers used by almost all fields of industry for storing granular materials and generally classified in two types: mass flowand funnel flow. One of the most important design parameter of these equipment is the discharge rate which depends on the flow mode. There are high numbers of analytical and empirical models used for determine this parameter, however none of them is suitable for bothflow modes; moreover the accuracy of mass flow models is not acceptable. Recently a few numerical discharge models are made forcertain geometries; but the applicability of these models in case of different flow modes was not examined. Aim of our work is the creationof an experimentally validated numerical discharge model based on others work and examination of this in term of different flowmodes. We prove that our modified model is suitable for determine silos discharge rate independently from flow mode.

INTERNAL MODEL-BASED ROBUST PATH-FOLLOWING CONTROL FOR AUTONOMOUS VEHICLES

Adorján Kovács,István Vajk 한국자동차공학회 2024 International journal of automotive technology Vol.25 No.2

The paper presents a new internal model control (IMC) based control technique for lateral trajectory tracking of autonomousvehicles. The controller’s proposed structure employs a robust, fault-tolerant nonlinear internal servo control with optimalreference generation concerning vehicle yaw stability and physical limitations. The presented inscription of the referencegeneration creates a convex optimization task that can be used in real-time applications. Improvements in yaw-rate stabilityof vehicle motion control are fi rst shown through simulation results performed in a Simulink environment. The controllerstructure was also implemented in a real-time model and was examined in a Mercedes C-Class vehicle. In this article, thesimulation results and the real-time measurements are presented. The results show that the proposed controller has higheffi ciency in disturbance rejection and lower sensitivity towards parameter changes compared to a model predictive control(MPC) structure.

Relationship of dairy heifer reproduction with survival to first calving, milk yield and culling risk in the first lactation

Fodor István,Lang Zsolt,Ózsvári László 아세아·태평양축산학회 2020 Animal Bioscience Vol.33 No.8

Objective: The aim of our study was to determine the associations of heifer reproductive performance with survival up to the first calving, first-lactation milk yield, and the probability of being culled within 50 days after first calving. Methods: Data from 33 large Holstein-Friesian commercial dairy herds were gathered from the official milk recording database in Hungary. The data of heifers first inseminated between January 1, 2011 and December 31, 2014 were analyzed retrospectively, using Cox proportional hazards models, competing risks models, multivariate linear and logistic mixed-effects models. Results: Heifers (n = 35,128) with younger age at conception were more likely to remain in the herd until calving, and each additional month in age at conception increased culling risk by 5.1%. Season of birth was related to first-lactation milk yield (MY1; n = 19,931), with cows born in autumn having the highest milk production (p<0.001). The highest MY1 was achieved by heifers that first calved between 22.00 and 25.99 months of age. Heifers that calved in autumn had the highest MY1, whereas calving in summer was related to the lowest milk production (p<0.001). The risk of culling within 50 days in milk in first lactation (n = 21,225) increased along with first calving age, e.g. heifers that first calved after 30 months of age were 5.52-times more likely to be culled compared to heifers that calved before 22 months of age (p<0.001). Calving difficulty was related to higher culling risk in early lactation (p<0.001). Heifers that required caesarean section were 24.01-times more likely to leave the herd within 50 days after first calving compared to heifers that needed no assistance (p<0.001). Conclusion: Reproductive performance of replacement heifers is closely linked to longevity and milk production in dairy herds.

Position of Hungarian Merino among other Merinos, within-breed genetic similarity network and markers associated with daily weight gain

Zsolnai Attila,Egerszegi István,Rózsa László,Mezőszentgyörgyi Dávid,Anton István 아세아·태평양축산학회 2023 Animal Bioscience Vol.36 No.1

Objective: In this study, we aimed to position the Hungarian Merino among other Merinoderived sheep breeds, explore the characteristics of our sampled animals' genetic similarity network within the breed, and highlight single nucleotide polymorphisms (SNPs) associated with daily weight-gain. Methods: Hungarian Merino (n = 138) was genotyped on Ovine SNP50 Bead Chip (Illumina, San Diego, CA, USA) and positioned among 30 Merino and Merino-derived breeds (n = 555). Population characteristics were obtained via PLINK, SVS, Admixture, and Treemix software, within-breed network was analysed with python networkx 2.3 library. Daily weight gain of Hungarian Merino was standardised to 60 days and was collected from the database of the Association of Hungarian Sheep and Goat Breeders. For the identification of loci associated with daily weight gain, a multi-locus mixed-model was used. Results: Supporting the breed's written history, the closest breeds to Hungarian Merino were Estremadura and Rambouillet (pairwise FST values are 0.035 and 0.036, respectively). Among Hungarian Merino, a highly centralised connectedness has been revealed by network analysis of pairwise values of identity-by-state, where the animal in the central node had a betweenness centrality value equal to 0.936. Probing of daily weight gain against the SNP data of Hungarian Merinos revealed five associated loci. Two of them, OAR8_17854216.1 and s42441.1 on chromosome 8 and 9 (–log10P>22, false discovery rate<5.5e-20) and one locus on chromosome 20, s28948.1 (–log10P = 13.46, false discovery rate = 4.1e-11), were close to the markers reported in other breeds concerning daily weight gain, six-month weight, and post-weaning gain. Conclusion: The position of Hungarian Merino among other Merino breeds has been determined. We have described the similarity network of the individuals to be applied in breeding practices and highlighted several markers useful for elevating the daily weight gain of Hungarian Merino.

Analytical approach of funnel flow discharge

Ferenc Safranyik,István Oldal 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.2

Design engineers often encounter problems because of the special mechanical behavior of granular materials. Such a typical problem is predicting discharge rate of silos and hoppers. This important design parameter must be known during the development of material transport devices attached to the container, but the calculation of this parameter may be challenging because well-known theories of hydrodynamics are not applicable. Several models are formed to evaluate discharge rate of silos, although most of them based on experimental observations are unable to explain physics of particle outflow. Oldal’s theory accounts for granular discharge of funnel flow, cylindrical silos with formation, and collapse of unstable arches above the orifice. It is applied to rectangular hoppers in this paper to generalize and prove this theory. An extended equation is derived by applying the original hypothesis that is validated using laboratory experiments and numerical simulations.

Role of Culture in the Relations Between Hungary and Korea

András Szüts,István Medvigy 한국외국어대학교 EU연구소 2023 EU연구 Vol.0 No.65

Identification of V-belt power losses with temperature measurement

László Kátai,István Szabó 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

The efficiency of V-belt drives is determined by several factors collectively: the slip occurring during drive transmission, the externalfriction occurring when the belt enters and exits the pulley as well as the hysteresis loss resulting from inner friction. An experimentalapparatus and calculation method was developed in order to determine the increase in temperature emerging from the contact of the beltand the pulley in idling mode. The tested V-belt piece was bent on a pulley performing alternating motion while the temperature of theV-belt was measured. During the testing the temperature generated in the V-belt was measured as a function of changes in three parameters(Pretension, diameter of pulley and bending frequency). On the one hand, the temperature generated in the V-belt can be estimatedwith the assistance of the function determined on the basis of the testing results. On the other hand the so-called damping factor characterizingthe contact with the pulley (The external friction when entering and exiting the groove) and the hysteresis loss (Inner friction) arealso determined. On the basis of the damping factor (x≈400 Ns/m2) of the V-belt involved in the experiments the other losses (Poth) occurringfrom the pulley-V-belt contact and internal friction may be estimated. With the help of the mathematical models defined for thepulley diameter and belt frequency, taking into consideration the minimization of heat generation, optimal parameters can be calculatedthat serve as beneficial references for designing and tuning V-belt drives.

Enhancement of the mixture quality of corn grains in a single-shaft paddle mixer using DEM simulations

Seifeddine Garneoui,Péter Korzenszky,István Keppler 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.3

Numerous powder manufacturing industries such as food and pharmaceutical require the use of mixers to ensure that loaded materials meet a certain level of uniformity to procure an end-product of a high standard. Studies concerning mixing issues still do not fully cover the choice of the optimal mixer parameters. In this paper, we investigated the effects of filling configuration and the number of paddles on the mixing rate in a single-shaft paddle mixer. We used bi-colored corn grains as solid particles and employed discrete element simulations using LIGGGHTS-PUBLIC®. To calculate the static friction, rolling friction, and the coefficient of restitution, we applied the box discharging technique. The coordinates-based mixing rate socalled nearest-neighbor index was employed to quantitatively examine the different mixing rates along the mixing period according to two variables, namely, filling type and paddle number. Filling one type of particles then filling the other type on top of it in the mixer achieves better mixing efficiency compared with sidewise filling of particles. The use of a high number of paddles improves the mixture uniformity, while using more than five paddles has no further impact on the mixture. Also, mixing is more efficient when dealing with particles that have the same or different number of clumps, whereas mixing spherical grains with five-sphere clump grains decreases the mixing efficiency considerably.