ANALYSIS OF VARIANTS OF STRUCTURES OF BUILT-UP COLUMNS ON EXAMPLES OF COLUMNS FOR CRANE RUNWAYS

U ovom radu je prikazana višekriterijumska analiza za dve varijante izvođenja složenih dvodelnih štapova koji su izrađeni od standardnih U profila, sa ispunom od spojnih limova, pri čemu su posmatrani na primerima stubova dizaličnih staza. U ovom istraživanju, pored različitih kriterijuma stabilnosti, analizirani su i različiti slučajevi provere čvrstoće, kao i nosivost šava kod veze spojnih limova sa U profilima. Takođe, izvšena je i optimizacija potrebnog broja spojnih limova, kao i njihovih dimenzija, za obe varijante složenih štapova, pri čemu se posmatralo kako se menja broj ovih limova, kao i njihova masa, pri povećanju sile pritiska na stub dizalične staze. Za postupak analize i optimizacije primenjen je alat Solver, kao i EA algoritam, u Ms EXCEL softveru. Primena ovakvog postupka se pokazalo opravdanim, pre svega zbog same prirode problema i analize, pri čemu se vrlo brzo može doći do potrebnih parametara pri projektovanju ovih tipova struktura. Takođe, pokazano je kako se menja ukupna masa stuba dizalične staze, pri promeni sile pritiska, za jednu i drugu varijantu, kao i poređenje masa stubova ovih varijanti.Publishe

THE IMPACT OF THE POSITION OF THE HYDRAULIC CYLINDER MOUNTING POINT ON THE CHASSIS LOAD IN MOBILE ELEVATING WORK PLATFORMS

The paper deals with the structural analysis of the typical mobile elevating work platform moving quasi-statically in the vertical plane. With certain approximations included a model for calculating load transmission from the basket to the support on the vehicle chassis has been developed. It allows tracking changeable load conditions for each structural element, as well as tracking force changes in each hydraulic cylinder of the articulating boom, depending on the angles of boom joints and the geometric parameters of boom sections. Derived analytical dependences can be used as the basis for design and optimization of the hydraulic installation and hydraulic component selection. On the other hand, the functions obtained enable position adjustment of the hydraulic cylinder mounting point of the first section in order to reduce the load impact on the chassis.Publishe

Employee Recruitment and Its Relationship with Employee Satisfaction: Verifying the Mediating Role of the Employer Brand

The transformation of a capital-intensive to knowledge-driven economy has marked the beginning of a new epoch in business doing. Carrying out business activities in an extremely dynamic environment has greatly reduced the importance of traditional concepts and techniques, which is the reason why the focus has shifted to human resources and their management. Accordingly, a company should attract, retain and motivate its employees in order to ensure a high level of their satisfaction by ensuring the achievement of strategic goals. A possible direction of achieving the desired position is based on the development of the employer brand. Therefore, the aim of this paper is to determine the impact of practice in conducting employee recruitment activities on their satisfaction, as well as the influence of the employer brand as a mediator on the identified relationship between the recruitment and satisfaction of employees in Serbia. The results of the conducted empirical research study have proven the existence of a statistically significant positive influence of employee recruitment on satisfaction, while the mediating influence of the employer brand has also been fully confirmed

Optimization of crane hooks considered as curved beams with different cross-sections – a comparative study using MATLAB

This paper presents the analysis and the optimization of the geometric parameters of different crane hook cross-section types. The study included trapezoidal, rectangular, square, elliptic, circular and T cross-section. The reduction of hook critical cross-section area was set as the primary goal for the optimization process. The criterion of maximum permissible stress is set as the constraint function, while the maximum stress values at the characteristic points were calculated according to Winkler-Bach theory, considering the hook as a curved beam. The optimization procedure was conducted using some metaheuristic optimization methods, in conjunction with known MATLAB functions. The goal of this research was to determine the optimum geometric parameters of mentioned cross-section types and to compare them in other to gain some conclusions and choice recommendations.Publishe

Comparative Analysis and Optimization of Different Cross- sections of Crane Hook Subject to Stresses According to Winkler-Bach Theory

The paper presents comparative analysis and optimization of the geometric parameters of different cross-sections of crane hook at the critical places. The reduction of the cross-sectional area of crane hook is primary goal of this research. The selected sections are trapezoidal, elliptic, parabolic and their special cases. Criterion of maximum permissible stress in the characteristic points of cross-section is set as constraint function. Some geometric limits are taken, too. Stresses are observed according to Winkler-Bach theory. Optimization procedure is performed by using the method of Lagrange multiplier and GRG2 algorithm. The obtained results of optimization for different types of cross-sections are compared with each other and with the geometric values of standard hook solution.Publishe

Effects of capacity sharing on delays and re-routings in European ATM

In this paper we analyse the effects of capacity sharing between Area Control Centres on delays and re-routings. We assume two different design options for capacity sharing (within Air Navigation Service Providers and within Functional Airspace Blocks) and compare them to a baseline scenario. Using the CADENZA optimization and simulation model, we build a case study of a busy day in the ECAC area, using 100 different scenario runs in order to capture traffic variability as well as capacity reductions. Results show that capacity sharing leads to a decrease of delay and re-routing costs that outweighs the additional costs of enabling capacity sharing even if we assume relatively high additional costs per shared sector-hour. Moreover, it can be shown that capacity sharing within ANSPs already delivers 3/4 of the benefits that can be achieved via capacity sharing within FABs.This project has received funding from the SESAR Joint Undertaking within the framework of SESAR 2020 and the EU's Horizon 2020 research and innovation programme under the Grant Agreement Number 893380.Peer ReviewedPostprint (published version

The Deflection of the Column-mounted Jib Crane with Tapered Boom by Finite Difference Method

One of the most frequently utilized crane types in industrial applications is the column-mounted jib crane. There are many different designs according to different requirements about lifting height, span, payload capacity, drive options, etc. Within the efforts to optimize the structure's mass, heavy-duty jib cranes with high payload capacity and extended reach often have their boom tapered. Besides strength, deflection is the most considered design criteria, where the crane structure is subjected to the total payload capacity at the tip of the boom. The paper presents the application of the finite difference method (FDM) and MATLAB code for the deflection of the column-mounted jib crane with a tapered boom. Obtained results are very close to the results from the finite element method (FEM) model in Ansys.Publishe