Summary determination of velocity and acceleration in the dead position of four-bar mechanism by the stopping method

The paper studies a plane four-bar mechanism in a dead, kinematically indeterminate position. From that position, the mechanism could continue to move, continuously, or the driven lever would stop and move backwards. But, if we eliminate this second possibility, the position of the mechanism is no longer indeterminate and it would be logical that we can determine unknown speeds and accelerations by some kinematic method. The authors of this paper, applying the stopping method, came up with analytical expressions for determining unknown velocities and accelerations in the dead position of an four-bar mechanism.

Evaluation of vehicle parameters depending on technical vehicle inspection

In a strategic document of EU for Road safety improvement, up to 2030, "safe vehicle" is recognized as one of the pillars of a stable Road safety system. The part of the "safe vehicle" pillar is technical vehicle ispection, where parameters important for road safety are periodically checked. The aim of this work is to determine the quality of the measurement data and the ability to repeat measurements of some parameters during technical vehicle inspection, or more precisely, to determine whether measured data of turning wheel resistance and brakes ovality differ depending on the inspection place. The research is done by inspecting ten vehicles at five inspection places with different levels of resources use. The results show that the spread of measured data of turning wheel resistance is statistically significant and that it depends on the inspection place, as well as that measured data of turning wheels resistance significantly vary between inspection places. The measured percentage of brakes ovality is different from one inspection place to another, but the differences are statistically significant only for right wheels. The impact of inspection place, although less than in turning wheel resistance measurement, is still significant.

Suitability of aggregates gradation for base and subbase layers of pavement

The assessment of the suitability of the granulometric composition of the crushed stone aggregates (CSA) for an unbound base and subbase layers of pavement, in the Republic of Serbia is done based on the defined gradation bands, uniformity degree (Cu), coefficient of curvature (Cz), percentage of fines and percentage of particles passing a 0.02 mm sieve. On the other hand, standards which define the quality requirements of aggregates and unbound mixtures for road construction SRPS EN 13242 and SRPS EN 13285 introduce a significantly different approach to the assessment of the granulometric composition suitability. Categories are defined. Each category includes a particular boundary band, tolerances on sieves, differences in values passing each sieve. The categories are defined depending on the field of the application. For seven CSA 0/31.5 mm used for the construction of Corridor XI, a comparative analysis of the granulometric composition suitability was performed according to the requirements of the existing Technical Specifications (TS) of PE "Roads of Serbia" (PERS) and the specified SRPS EN standards. The analysed curves satisfy those technical requirements, but vary in categories from the most severe mixtures of the normal granulometric composition of the GA category, to the open mixtures of the GP category. It was concluded that the principle based on the defining allowed tolerances on the sieves and between the sieves, is more suitable for field control of of the granulometric composition and the good granularity of the aggregates. Technical Specifications should be modified to this approach.

Configuring a new educational machine tool based on hybrid kinematic mechanism

The paper shows the configuration of a new educational machine based on hybrid kinematics mechanism. The concept of a three-axis O-X hybrid mechanism is described, consisting of a single serial translational axis and a two-axis parallel mechanism that can operate in two variants, with extended form O and crossed form X-joints of the parallel mechanism. The virtual prototype of the machine was configured in a CAD/CAM environment, where simulations of the mechanism's operation were performed. A programming system for machine has been prepared that also enables program verification. An open architecture control system based on the LinuxCNC platform has been configured for control of the machine. The trial work of the machine was performed in order to verify the realized prototype and control.

Assessment of sustainability of different renewable energy systems based on life cycle exergy analysis

The sustainable development of energy systems does not only involve the use of renewable energy resources but the increase in their efficiency as well, enabling society to maximise the benefits of their consumption. The production of electrical energy from clean and renewable sources contributes to lowered fossil fuel exploitation and the reduction of its damaging effect on the environment. This is a way to reach the global target of sustainable development - striking a balance between resource consumption and the achievable natural cycle regeneration. Environmental protection is in the focus of attention. Namely, when energy system sustainability is assessed, in addition to the ecological sustainability assessment (based on life cycle analysis - LCA), attention should be paid to the decrease in energy quality in energy processes (exergy loss). This paper presents the thermodynamic approach to energy system sustainability assessment by applying life cycle exergy analysis (LCEA). The key issue is the assessment of systems which use sustainable energy sources: the wind turbine and the stand-alone photovoltaic solar system.

Urban regeneration of the industrial zone in Smederevo: Comparative analysis

This paper has a focus on Urban Regeneration, with the "still-active" industrial complex as the main element, on the Eastern outskirt of the City of Smederevo. It includes revitalization and networking with the cultural assets of the city, emphasizes their importance in terms of traditional and tourist conditions, in direct communication with a necessary urban methods for the revitalization of the entire area and the City of Smederevo. Due to the Comparative analysis of the "good practice" examples of the similar cities in Italy, the valorization of space and approaching the basic goal of the research has been performed. The aim of the research of this paper is to achieve the most effective urban regeneration and the new level of intervention along with the settings of guidelines for improving the quality of the completely coverage of the zone in which the complex is located, not only the certain zone of the industrial complex.

Influence of synthesis parameters on mechanical properties of nanocomposite PMMA-MXene

In this paper, the influence of solvents and reinforcement processing methods on the mechanical properties of nanocomposite poly-(methyl methacrylate) PMMA-Ti3C2Tx MXene was investigated. A weight fraction of reinforcement was 1% and two types of solvents were used for sample preparation: dimethylformamide (DMF) and acetone (Ac). Deionized water and DMF were used to delaminate the MXene. An additional peak at 1675 cm-1 was observed on the FTIR spectra of the obtained samples, which indicates that some amount of DMF remained in the material after drying. The results of microindentation show that samples where MXene was delaminated in deionized water and PMMA dissolved in acetone had a 74.46% higher reduced modulus of elasticity, which is supported by SEM images where better dispersion of MXenes is observed.

Understanding cyber technologies in a physical way

In this paper, we would discuss a bit more how cyber technologies operate in a physical way and why it's important to understand the limitations of a physical reality. So commonly - mathematical terms would get assumed as abstract - so they could be considered as somehow perfect. On the other hand, the reality would offer many boundaries and obstacles that should be avoided or better explained. As it's known, cyber technologies belong to digital systems containing so many electronic components that would have their physical performances. Those performances as well as the entire cyber defense of such digital technologies would be analyzed deeper through this effort.

Analysis of HDF curves for the formation of functional dependence in the wider area of the Republic of Srpska

In hydrotechnical practice, there is a great need to use precipitation data in the wider area of the area where the research is being done. The lack of precipitation stations that can register shorter-duration rainfall, less than 24 hours, poses a huge problem for Engineers in practice. Based on this work, an analysis of existing precipitation data is used to create a functional dependence on the wider region based on the available data. Thus formed functional dependency facilitates the solving of a large number of hydrotechnical problems. This work shows the formation of a mathematical model based on MS.

An overview of methods for eliminating the effects of interference in an active high-voltage power facility

In this paper, practical and conceptual problems related to the way of suppressing or eliminating the influence of interference (at a frequency of 50 Hz) in an active high-voltage power facility are discussed. The problem is relevant in the context of measuring the safety characteristics of the grounding system: grounding system impedance, touch voltage and step voltage. The paper gives an evolutionary overview of title methods. The review focuses on the characteristic problems and shortcomings of individual methods. Also, the basic characteristics of the author's FSM (Frequency Shift Method) method, which guarantees precise control of interference, are elaborated. In this sense, the FSM method is the basis for accurate and economical measurement of the safety characteristics of the grounding system.