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Linear systems in Gauss-type quadratures for variable-sign weight functions
No full textWe consider a recently proposed Gauss-type quadrature formula with respect to a weight function that changes sign in the interior of the integration interval. An important step in its construction is to introduce a modifier function used to transform the given integral into a sum of one integral that does not cause a quadrature error and the other integral with a property that the points from the interior of the integration interval at which the weight function changes sign are the zeros of its integrand. Determining a modifier function requires solving an associated system of linear equations. For the same integral, different modifier functions can be chosen, and hence different linear systems can be obtained. From a theoretical perspective, only necessary is that the associated system has a solution, but from a computational perspective, it is also important that the associated system is not too ill-conditioned and that the structure of its matrix is as simple as possible. We analyze the conditions under which it is guaranteed to obtain, for instance, a system with a Vandermonde matrix or a system with an identity matrix. We also give examples where systems with an arbitrary matrix are obtained, both those that have and those that do not have a solution
Pareto Optimization as the Basic for Selecting Robotic Mechanic Assembly Technologies
No full textThe task of selecting robotic mechanic assembly technologies (RMAT) is considered as a multi-criteria optimization task, which in this formulation is solved on the set of previously obtained solutions regarding the selection of RMAT. The purpose of the paper is to increase the efficiency of technological preparation of robotic mechanical assembly production of machine and instrument engineering due to a new approach to the selection of RMAT using Pareto optimization and the peculiarities of the selection task formulation. The novelty consists in the further development of a science-based approach to solving multi-criteria selection task, based on the first proposed formalisms of the specified process, which reflect the peculiarities of the selection task formulation, its meaningful essence and the content of the Pareto optimization method. The practical value of the research lies in the proposed engineering- acceptable approach to solving applied multi-criteria selection tasks on the example of RMAT selection, which is invariant to the statement of the selection task, the dimension of the task, and its meaningful essence. The methods of discrete optimization, fuzzy multi-criteria selection of alternatives, and the Pareto optimization method were used for the research. The main results of this work consist of the development of formalisms and the demonstration of the efficiency of the proposed approach for the applied task of RMAT selection. The peculiarity of the developed approach is the combination of Pareto optimization, performed on a discrete set of local criteria. Directions for further research are presented
Mechanical behavior of ship to shore container crane subjected to different stochastic wind actions.
No full textExperimental and numerical research of the flow inside the control valves trim
Get PDFIn this paper are presented desing, testing and numerical analysis for two manufactured control valve trims. Valve trim is consisted of cage or dick stack, plug, stem and seat. Size from app. 15.88 mm (0.625 in) up to 101.6 mm (4 in) is suitable for 3D metal and plastic print, what is presented in this paper. Selective laser melting 3D metal printing is applied on the disc presented in this paper. Even better material properties from rest of the valve parts could be obtained. This is of great importance for valve retrofitting. In this paper is presented, also, new developed channel geometry, what is followed by various fluid flow phenomena. Measurement results for second prototype manufactured by 3D printing using plastics are presented in details. Here is shown, in short, procedure for determination of KV values of the test valves according to the EN 60534-2-3, Industrial-process control valves - Part 2-3: Flow capacity - Test procedures. In addition, some aspects of CFD calculations are presented
Error bound of Gaussian quadrature rules for certain Gegenbauer weight functions
No full textIn this paper we present an extension of our previous research, focusing on a method to numerically evaluate the error term in the Gaussian quadrature formula with the Legendre weight function, as discussed by Jandrlic et al. (2022). For an analytic integrand, the error term in Gaussian quadrature can be expressed as a contour integral. Consequently, determining the upper bound of the error term involves identifying the maximum value of the modulus of the kernel within the subintegral expression for the error along this contour. In our previous study, we investigated the position of this maximum point on the ellipse for Legendre polynomials. In this paper, we establish sufficient conditions for the maximum of the modulus of the kernel, which we derived analytically, to occur at one of the semi-axes for Gegenbauer polynomials. This result extends to a significantly broader case. We present an effective error estimation that we compare with the actual one. Some numerical results are presented
Ergonomic Adjustment Needs of Transport and Mining Machines: A Preliminary Study of Operators’ Attitudes in Serbia
No full textPrevious studies suggests that accidents and/or incidents involving heavy machinery are unanticipated and unfortunate occurrences most frequently caused by human error. Therefore, the primary objective of this research was to conduct a preliminary investigation into the views held by operators of transport and mining machinery towards the ergonomic adjustment of their work environment to accommodate their specific needs. Namely, the aim of this paper is to analyze the various factors that contribute to the degradation of working conditions, leading to the emergence of occupational diseases and to the likelihood of accidents and incidents. In this research, the factors that influence the possibility of human error due to unfavorable workplace conditions, ergonomic characteristics of the cabin, the physical condition of the operator, job satisfaction and management commitment were analysed, as those factors are recognized by previous research.The research utilized a questionnaire tool to gather data from individuals operating machinery in the transportation and mining industries. There were 93 operators of transport and mining machines willing to participate in this survey, of which 65 were operators of various mining machines, while 28 operators worked on cranes. All surveyed crane operators have an average height in the range of 165-182 cm and a weight of 70-102 kg. Surveyed operators of mining machines have an average height in the range of 166-190 cm, but there are high deviations from the average weight, i.e. 9.23% of them have a weight of over 110 kg, that is, the weight is in the range of 60-150 kg. The examined machines included cranes with a span from 9 to 25 m and its load capacity from 10 to 160 tons, as well as excavators, bulldozers, drills, dumpers, backhoe loaders, bucket wheel excavators and loaders. The data was subsequently subjected to further analysis using descriptive statistics, cluster and principal component analysis. The study's results have provided evidence to support the initial premise, suggesting that human error is the primary cause of accidents and incidents involving transportation and mining machinery. The main cause factor, as perceived by a considerable majority of mining operators (79.9%) and crane operators (40%) is human error. The results suggest that there are differences in the ergonomic adjustment of workplaces of mining and transport machinery operators in manner that mining industry workplaces are better adjusted then transport industry workplaces.Cluster and principal components analysis led to the following conclusions. The key factors affecting the reduction of the quality of the working conditions of operators on mining machines are related to the seat rotation, absence from work due to poor working conditions (sick leave), nonadjustable armrests or non-existing armrests or armrests which are not set at the right height. The key factors that affect the quality of the crane operator's working conditions, are connected to characteristics of armrests (no armrests, armrests not at the right height, armrests are not adjustable), seat characteristics (seat height is not adjustable, seat is not adjustable horizontally, seat has not lumbar support, seat cannot recline, seat cannot be rotated), controls adjustment issues, the temperature in cabin regulation, visibility issues and to the absence of management commitment.A general recommendation as a measure to improve working conditions for operators of mining and transport machines is the usage of ergonomically adjusted seats with armrests. A proposal to introduce cameras that provide operators with better side and rear visibility could be considered, too, in aim to reduce the burden on the operator during reversing movements. In terms of management commitment, further focus on ergonomics climate is necessary to enable better working conditions for mining and transport machinery operators.Sample size enlargement is proposed as the future research avenue
The innovative method for determining the approximate value of the Bond work index
No full textIn this study, we examine an innovative approach to determining the Bond work index, a key
parameter in the mining and cement production industry that indicates material grindability. The
method relies on the first-order kinetics law and allows for the estimation of approximate index
values with any number of grinding cycles, depending on the desired data accuracy. An important
aspect of this approach is the multiplication of parameters G and P80 for each cycle by specific
coefficients, achieving values close to those of the last grinding cycle when equilibrium is
reached in the standard test. In this paper, we compare the results obtained by the innovative
method with the standard Bond procedure on various samples of mineral materials. Our analysis
shows a significant reduction in the mean square error as the number of grinding cycles increases,
indicating increased precision of the new approach
ARTIFICIAL NEURAL NETWORKS IN THE ANALYSIS OF SAFETY AND ERGONOMIC ASPECTS OF CABS OF MINING MACHINES
No full textPrethodna istraživanja su ukazala na značaj uticaja ergonomskih i ponašajnih faktora na bezbednost i zdravlje na radu rukovalaca rudarskim mašinama. U ovom istraživanju analiziraju se bezbednosni aspekti rada koristeći podatke o fizičkim karakteristikama rukovaoca i ergonomskim uslovima rada u rudarskoj industriji, tačnije u kabinama šest različitih tipova rudarskih mašina (buldozer, bager, damper, kombinirka, bušilica i utovarivač). Analiza je sprovedena nad podacima prikupljenim anketiranjem 61 rukovaoca rudarskim mašinama o ergonomskim faktorima, koji utiču na mogućnost povreda na radu. Primenom veštačkih neuronskih mreža, izvršeno je predviđanje pojave povreda. Rezultati pokazuju visok stepen tačnosti modela, što sugeriše mogućnosti unapređenja bezbednosti i zdravlja na radu kroz ergonomske intervencije i daje preporuku za dalju primenu veštačke inteligencije u rudarskoj industriji
Research and Engineering Activities in the Field of the Fire Protection at the UCIPS and the UB FME
No full textAt the University of Criminal Investigation and Police Studies (UCIPS) and the University of Belgrade Faculty of Mechanical Engineering (UBFME) are conducted research and engineering activities of interest for the complex topics with focus on the fire protection. In this paper will be presented in short research and engineering activities at both universities and three departments. Technical means of the police, Forensic engineering, Trasology, Termographic tests, Inspection and technical supervision, Analytical methods in forensic sciences, Expertise in forensic engineering, Forensic processing of the crime scene, Prevention and suppression offires, accidents and explosions, Tactics of special purpose police units, Security system for person and property, Environmental safety, Safety in emergency situations, Risk menagement in the protection and rescue system, Security protection of persons and property are studied at the UCIPS. At the UB FME are studied Risk analysis and Design of fire protection systems, Testing of the fire protection equipment and Expert analysis for court cases of fire accidents. In addition, at the UB FME Hydraulic Machinery and Energy Systems Department are studied, and developed pumps, fans and compressors with adequate systems and fluid flow measurement techniques
DESIGN KNOWLEDGE V.S. GENERATIVE AI
No full textThe application of artificial intelligence (AI) is still a controversial topic in creative disciplines. Recent advances in AI field like generative adversarial networks (GAN) and large language models (LLM) brought about conditions for the development of numerous content creation systems that today are referred to as generative AI. Since architecture, as one of the creative disciplines, deals with the generation of models and documentation on the basis of which buildings are built; naturally the notion of generative AI has attracted a lot of attention.
However, the application of these technologies requires a detailed understanding of the algorithms underlying generative AI, as well as the nature of the architectural process. Most current AI algorithms are based on learning from existing digital media such as text, graphics, audio, and video. For the typical person today who consumes all content through electronic media, this seems like a universal solution for all disciplines. However, the architectural process is far more complex. First, the texts and drawings that the architect creates are not the final expression but constitute a representation of the architectural object being designed. On the other hand, design knowledge is not classical propositional knowledge, but knowledge in action that is created through the design process and which as such can never be complete and represented in some static form. Considering that the life of architectural objects is mainly limited by the failure of the object's function and not its construction, design knowledge represents a crucial link in ensuring the resilience of architectural objects.
The paper provides a fundamental analysis of existing AI deep learning algorithms, as well as a study of theories about the design process and considers the ways in which they can be interconnected