• MACHINES

    Influence of trolley motion in the dynamic behavior of semi-portal cranes

    Machines. Technologies. Materials., Vol. 15 (2021), Issue 5, pg(s) 170-175

    The paper presents dynamic analysis of the Semi-Portal Cranes for the case of Trolley motion travelling on Crane’s Girders. Semi-portal cranes are mainly mounted in the industrial facilities, and they consist of metallic structures with big dimensions and many mechanisms that carry heavy loads. We will analyze the influence of the Trolley motion in the dynamic behavior of Semi-Portal Crane while carrying maximum Load, in particular the influence of Load swinging and oscillations. The method of analysis is acquiring experimental measurements and comparing those results with the results gained through modeling of crane, and carrying simulations. Designing the Crane’s 3D model with software and motion simulations is the method applied in the paper to analyze dynamics and is important to explain the form and intensity of oscillations that can cause accidents, failures of parts, and other concerns about the safety. Analysis will be done for maximal and minimal speed of the Trolley. Conclusions from this paper will be useful about the design, dynamic response and safety of Semi-Portal Cranes. The analysis will be focused to find main kinematic and dynamic parameters influencing the crane dynamics, like forces, moments, speed (velocity), and Load swinging magnitude. The Crane is modeled based on the Data from standard manufacturer of Semi-Portal Cranes.

  • TRANSPORT TECHNICS. INVESTIGATION OF ELEMENTS. RELIABILITY

    Scissor lift dynamic analysis and motion regulation for the case of lifting with maximum load

    Trans Motauto World, Vol. 6 (2021), Issue 2, pg(s) 38-42

    This paper deals with Dynamic analysis of Scissor Lifts during the Load Lifting to determine their dynamic behavior, find the nature of oscillations, and the regulation of lifting to minimize these oscillations and optimize the work process. During the motion processes, the lift and its main parts undergo heavy forces, moments, and oscillations. The method of research is acquiring results through design, modeling, and simulations, comparing them with analytic calculations, and looking for the optimal motion regulation of the Load Lifting. The analysis will be acquired when the Scissor lift is carrying maximum Load. The study will be concentrated in the finding the nature of dynamic forces and stresses that acts on the main parts of the lift and the extent and the form of oscillations. Results will be shown in the form of diagrams and contour views as the solution results of the tested system. Modeling and simulations will be carried using software SimWise 4D, based on the type of the Scissor Lift taken from Standard Manufacturer. Conclusions of these analyses are useful for design considerations, dynamic behavior, and safety of these types of lifts.

  • THEORETICAL FOUNDATIONS AND SPECIFICITY OF MATHEMATICAL MODELLING

    Modeling of аgent-based cyber-physical systems using goal-oriented approach

    Mathematical Modeling, Vol. 4 (2020), Issue 4, pg(s) 106-109

    Cyber-physical systems (CPS) integrate computing, networking and physical dynamics and are characterized by a high degree of heterogeneity and parallelism, with high dimensionality and complexity, including a variety of decision-making capabilities and control logic. Modeling and simulation of cyber-physical systems are considered important stages in the design, development and operation of CPS and their components. The main aim of the paper is to describe and analyze the evolution of agent based approach in the field of CPS and to define the basic requirements to the agent based systems regarding CPS. Based on O-MaSE methodology a software process model for agent based development of CPS is proposed. The approach includes the creation of 10 models reflecting various aspects and functionality of the CPS. The suggested approach is analyzed in terms of meeting the basic requirements for agent-based systems, imposed by the peculiarities of cyber-physical systems and fundamental requirements for their introducing, such as flexibility/changeability, reliability, reconfigurability, adaptability/agility and dependability.

  • DOMINANT TECHNOLOGIES IN “INDUSTRY 4.0”

    Applications of contemporary software systems for piezoelectric beams investigations

    Industry 4.0, Vol. 5 (2020), Issue 4, pg(s) 179-180

    This paper presents investigations of vibrations of cantilever beams with piezoelectric layers. The paper discusses the contemporary engineering and scientific software systems in order to select the appropriate for the study of mechanical and electrical dynamic behavior of piezoelectric beams.The system COMSOL has been chosen and a study with it has been stated with a static analysis and an eigenvalue analysis. Conclusions are made and a frequency response and time dependent investigations are planned to be done.

  • INNOVATIVE SOLUTIONS

    A review of modeling pem fuel cells for monitoring applications

    Innovations, Vol. 8 (2020), Issue 2, pg(s) 89-94

    Low operating temperature, compactness, high efficiency as well as low to zero emissions are features that cause large interest in Proton Exchange Membrane (PEM) fuel cells and are reasons that application of this technology is considered in many areas. However, for a massive deployment of the PEM fuel cell technology to the market, good control and monitoring are mandatory to increase efficiency and durability. For the control and monitoring of PEM fuel cell systems, appropriate system models are required. In this study, a review of modeling approaches to the PEM fuel cell systems is considered

  • Electrodeposition of copper on cold rolled copper substrate

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 6 (2020), Issue 1, pg(s) 11-14

    The microscopic and macroscopic views of copper electrodeposits obtained on plastically deformed copper substrates of different deformation degrees have been investigated. Experiments have been performed under galvanostatic conditions. There appear, depending upon the degree of reduction realized during substrate rolling, three types of deposit: epitaxial, homogenous and texture. Epitaxial growth is observed on unreformed substrate and on the substrates with lesser deformation degree (up to 60 %). With the increase of the substrate reduction degree, heterogeneous type of the deposit appeared and the phenomenon of twinning was stated. On very much deformed substrates, as well as in presence of organic additives, field oriented texture type of the deposit is obtained. On very deformed substrates macroscopic uneven deposits appeared, with the linear structure which follows the direction of substrate rolling. Possible explanations of this phenomenon are given.

  • MATHEMATICAL MODELLING OF TECHNOLOGICAL PROCESSES AND SYSTEMS

    Study the work of specialized car service as queue theory

    Mathematical Modeling, Vol. 4 (2020), Issue 1, pg(s) 31-34

    Study the refusal of requests received in a specialized automotive service workshop in the city of Rousse was investigated. The present work analyses the average monthly requests from customers of the workshop and the number of the actual repairs is determined. The work in the service have been seen as a mass service system with a non-stationary mid-month incoming stream with queries. Under nonstationary conditions, the basic values of the system parameters were calculated and Mat Lab application was created. The proposed approach can serve as a methodology for analysing and optimizing the activity of other universal automotive service

  • DOMINANT TECHNOLOGIES IN “INDUSTRY 4.0”

    SIMULATION OF SURGE PROTECTION ACCORDING IEC 61000-4-5

    Industry 4.0, Vol. 4 (2019), Issue 6, pg(s) 293-296

    An important requirement of digital electronic devices is the comprehensive provision of electromagnetic compatibility. In particular, it is necessary for electrical, electronic and radio equipment to ensure a sufficient level of noise immunity when exposed to microsecond pulse interference. The international standard IEC 61000-4-5 regulates the testing of equipment for microsecond impulse noise. Carrying out such physical tests is quite complicated and requires expensive equipment. The article proposes computer simulation of testing electronic devices in accordance with the requirements of IEC 61000-4-5.

  • MATHEMATICAL MODELLING OF SOCIO-ECONOMIC PROCESSES AND SYSTEMS

    SECURITY THREAT PROPAGATION MODEL CIVIL AVIATION FACILITY

    Mathematical Modeling, Vol. 3 (2019), Issue 2, pg(s) 70-72

    In the last few years there has outlined a well-defined tendency to consider aviation security with regard to the optimal management of its level with the consistent solution of the identification, measurement, evaluation and decision-making problems. For this purpose aviation security is shown as a state related to the object’s under study defined parameters, the quantitative display of which in the dynamics of their changes under the influence of external and internal factors remains in acceptable limits in terms of the object’s operation. However, the environment is formed by the object’s safety equipment, which represent a definite list of technical and other functional elements, solving the problem of the internal and external factors countermeasure. If we consider the situation of counter-strategy as a pseudo field, the proposed model belongs to the class of boundary value problems described by partial differential equations. The problem has no analytical solution, and computational modeling is very limited by mathematical formalization’s issues. It is offered to use hybrid computer tools, which have undoubted advantages in this case.

  • TECHNOLOGIES

    Investigation and analysis of electrochemical machining of 321-Stainless Steel based on response surface methodology

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 7, pg(s) 298-301

    Electrochemical machining (ECM) is prevalent and competitive manufacturing process which uses for machining of hard and tough materials in high tech industries. Hence, experimental investigations on ECM of different materials play essential role to effectively utilize this process. This paper demonstrates a systematic approach for achieving comprehensive mathematical models in order to investigate the effect of machining parameters on the process responses of 321-Stainless-Steel and analysis of machining performance based on the response surface methodology (RSM). Machining voltage, tool feed rate, electrolyte flow rate and concentration of NaNO3 solution were considered as the machining parameters while material removal rate (MRR) and surface roughness (Ra) were considered as the process responses. Experimental plan was performed by a central composite design (CCD), and the proposed mathematical models statistically have been evaluated by analysis of variance (ANOVA). Analysis shows that the RSM method has been appointed properly as the design of experiments (DOE) method for resolving curvature in ECM process responses. Also, the results show that the machining performance is greatly influenced by machining parameters. Especially the voltage and electrolyte concentration are the most important parameters.

  • Importance of mathematical modeling in innovation

    Mathematical Modeling, Vol. 3 (2019), Issue 1, pg(s) 32-34

    Mathematical modeling is the key parameter in designing new devices. Renewable energy technologies are getting higher importance in the near future. Mathematical modeling of circulating fluidized bed (CFB) biomass combustion could improve both their design and operation, reduce any associated problems and facilitate the implantation of this technology. A good understanding of the combustion and pollutant generating processes in the gasifier can greatly avoid costly upsets. Presently, there is a focus on developing models of CFB for burning biomass and waste material. The objectives of these models are to be able to predict the behavior with respect to the combustion efficiency, fouling problems and pollutant emissions performance of different fuels or mixtures in commercial CFBs. In this study, importance of mathematical modeling in designing CFB biomass gasifiers is investigated in view of innovative solutions.

  • Traffic synthetic model development and calibration in Anamorava region

    Machines. Technologies. Materials., Vol. 13 (2019), Issue 4, pg(s) 173-177

    The main objective of this paper is to develop and calibrate traffic synthetic model for forecasting traffic demand in Anamorava region. The model on existing situation is developed based on “meta model” which uses PTV Visum software. In order to set up a model were taken into account input variables number of residents, number of people employed, working places available as well as the traffic volume entering and exiting this region at “peak hour”. With intention to have traffic volumes as an outcome expressed as AADT, correction coefficients are applied. Multiplying the traffic volumes with correction coefficient there is traffic demand gained for the period of 24 hours which is an indicator to be used for comparison of results. In order to get the reliable model for forecasting, calibration of it is done through TFlow Fuzzy algorithm technique based on GEH test, R2 and percentage deviation criterions. Once the level is completed satisfactory, the final model can be used to forecast the traffic demand for this region.