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The paper presents a comprehensive identification and assessment of occupational hazards related to the operation of robotic welding systems. New technology fundamentally improves quality and accuracy of welds, especially precise narrow seams connecting thin sheets or profiles. The paper draws attention to typical occupational hazards occurring in the workplace, as well as those resulting from the use of robotic welding devices. Risk assessment was performed using the commonly used RISK SCORE method. Moreover, as part of our own research, the employee’s reliability levels were determined by determining the probability of making a mistake. The human factor reliability study was carried out using HRA (Human Reliability Analysis) methods. The classic TESEO and HEART approaches have been expanded to include additional factors, such as human-machine interface (HMI), cognitive load, quality of documentation and procedures, and task ambiguity. This addition addresses a significant methodological gap in classic HRA analyses, which have so far overlooked these key aspects that influence the effectiveness and safety of human-robot interactions.

The paper presents a simplified model of the effective thermal conductivity (ETC) of a bundle of circular steel bars. This model is a modification of a previously introduced detailed model, in which the ETC value is determined based on an analysis of thirteen thermal resistances. In the simplified model, the number of resistances was reduced to four, and some of the equations describing individual resistances were modified. In the computational section, the results of both models were compared. Calculations were performed for twelve cases, determined by bar diameters (10, 20, 30, and 40 mm) and three bundle porosities (0.09, 0.14, and 0.21). The bars were assumed to be made of steel with 0.2% carbon content and a surface emissivity of 0.7. Air was considered as the gas filling the gaps in the bundle. The calculations were carried out for a temperature range of 25–800 °C. It was found that, compared to the detailed model, the simplified model yields values that are on average about 4.8% higher. For this reason, a correction factor of 0.954 was introduced into the simplified model. After applying this correction, the results of the simplified model deviate from those of the detailed model by only about 1%. The simplified model was also used for a qualitative analysis of heat transfer within the bundle. It was determined that, depending on temperature and bar diameter, the gap resistance is higher than the bar layer resistance by a factor of approximately 3 to 49. Moreover, it was shown that contact conduction is the key thermal phenomenon during the heating of the bundle. In this way, more than 60% of the thermal energy is transferred in the bundle gaps. The results of the presented model can serve as a valuable source of information for optimizing the heat treatment processes of steel bars.

DynPy is an open-source library implemented in Python (version 3.10.12) programming language which aims to provide a versatile set of functionalities for mechanical and electrical engineers. It enables the user to model, solve, simulate, and report analysis of dynamic systems with the use of a single environment. The DynPy library comes with a predefined collection of ready-to-use mechanical and electrical systems. A proprietary approach to creating new systems by combining independent elements defined as classes, such as masses, springs, dampers, resistors, capacitors, inductors, and more, allows for the quick creation of new, or the modification of existing systems. In the paper examples for obtaining analytical and numerical solutions of the systems described with ordinary differential equations were presented. The assessment of solver accuracy was conducted utilising a coupled electro-mechanical model of a direct current motor, with MATLAB/Simulink (R2022b) used as a reference tool. The model was solved in DynPy with the hybrid analytical–numerical method and fully analytically, while in MATLAB/Simulink strictly numerical simulations were run. The comparison of the results obtained from both tools not only proved the credibility of the developed library but also showed its superiority in specific conditions.

We study the application of electromagnetic actuators for the active stabilization of the Leipholz column. The cases of the compressive and tensional load of the column placed in air and in water are considered. The partial differential equation of the column is discretized by Galerkin's procedure, and the stability of the obtained control system is evaluated by the eigenvalues of its linearization. Four different methods of active stabilization are investigated. They incorporate control systems based on feedback proportional to the transverse displacement of the column, its velocity and the current in the electromagnets. Conditions in which these strategies are effective in securing safe operation of the column are discussed in detail.

The paper presents analysis of nonlinear response of a classical mechanical oscillator placed within a magnetic field and driven by a harmonic force. With an appropriate choice of control parameters, the system vibrates chaotically between different equilibrium positions. To prove this result, Lyapunov exponents have been calculated using the algorithm proposed by Rangarajan G., Habib S. and Ryne R. [18]. Moreover, the appropriate time series, phase portrait, Poincaré cross-section and power spectrum are given to support the conclusion.

Rotating elements supported on journal bearings are widely encountered structures in engineering practice. Most commonly, these are asymmetrically manufactured and loaded rigid rotors transmitting torque and carrying transverse as well as axial forces. Nowadays, despite high operational demands and high rotational velocities, such systems are still expected to exhibit stable working, even in the presence of small assembly deviations, light unbalance or external disturbances. The surrounding environment of a rotating machine may interact with it by kinematic excitation from vibrating foundation. This, in turn, may lead to hazardous response and the onset of irregular and chaotic motion of the rotor. The subject of the study is to find and analyze regions of the occurrence of such vibrations in the system of a rigid rotor supported in journal bearings. The bearings themselves are assumed to be non-perfectly mounted in the housing, i.e., their sleeves are inserted in rings possessing some viscoelastic properties. These properties are treated as variable parameters, and the aim is to move the regions of irregular and chaotic vibration outside the operational regime (angular velocity). The adjustability of the viscoelastic parameters may be realized by incorporation of smart materials such as piezoelectric or magnetorheological ones. The considered system is an asymmetric rigid rotor supported on two journal bearings subject to a steady kinematic excitation. The system is described by eight coupled nonlinear ordinary differential equations of motion. Results of the examinations prove that by selecting an appropriate magnitude of damping and stiffness of the bearing mountings, it is possible to enlarge the region of stable operation of the rotating system and thus secure its safety. This, however, does not mean the elimination of chaotic response at all, but only a shift of it outside the range of operational rotation speed.

Following the glutamatergic theory of schizophrenia and based on our previous study regarding the antipsychotic-like activity of mGlu7 NAMs, we synthesized a new compound library containing 103 members, which were examined for NAM mGlu7 activity in the T-REx 293 cell line expressing a recombinant human mGlu7 receptor. Out of the twenty-two scaffolds examined, active compounds were found only within the quinazolinone chemotype. 2-(2-Chlorophenyl)-6-(2,3-dimethoxyphenyl)-3-methylquinazolin-4(3H)-one (A9-7, ALX-171, mGlu7 IC50 = 6.14 µM) was selective over other group III mGlu receptors (mGlu4 and mGlu8), exhibited satisfactory drug-like properties in preliminary DMPK profiling, and was further tested in animal models of antipsychotic-like activity, assessing the positive, negative, and cognitive symptoms. ALX-171 reversed DOI-induced head twitches and MK-801-induced disruptions of social interactions or cognition in the novel object recognition test and spatial delayed alternation test. On the other hand, the efficacy of the compound was not observed in the MK-801-induced hyperactivity test or prepulse inhibition. In summary, the observed antipsychotic activity profile of ALX-171 justifies the further development of the group of quinazolin-4-one derivatives in the search for a new drug candidate for schizophrenia treatment.

The motivation for this research was the need for a reliable prediction of the distribution of microstructural parameters in steels during thermomechanical processing. The stochastic model describing the evolution of dislocation populations and grain size, which considers the random phenomena occurring during the hot forming of metallic alloys, was extended by including phase transformations during cooling. Accounting for a stochastic character of the nucleation of the new phase is the main feature of the model. Steel was selected as an example of the metallic alloy and equations describing the nucleation probability were proposed for ferrite, pearlite and bainite. The accuracy and reliability of the model depends on the correctness of the determination of the coefficients corresponding to the specific material. In the present paper these coefficients were identified using the inverse analysis for the experimental data. Experiments composed constant cooling rate tests for cooling rates in the range 0.1-20 °C/s. The inverse approach to a nonlinear model is ill-conditioned and must be transferred into an optimization problem, which requires formulating the appropriate objective function. Since the model is stochastic, it was a crucial, yet demanding task. The objective function based on a metric of the distance between measured and calculated histograms was proposed to achieve this goal. The original stochastic approach to identifying the phase transformation model for steels was tested, and an appropriate optimization strategy was proposed.

The need for a reliable prediction of the distribution of microstructural parameters in metallic materials during processing was the motivation for this work. The model describing the evolution of dislocation populations, which considers the stochastic aspects of occurring phenomena, was formulated. The validation of the presented model requires the application of proper parameters corresponding to the considered materials. These parameters have to be identified through the inverse analysis, which, on the other hand, uses optimization methods and requires the formulation of the appropriate objective function. In our case, where the model involves the stochastic parameters, it is a crucial task. Therefore, a specific form of the objective function for the inverse analysis was developed using a measure based on histograms. The elaborated original stochastic approach to modeling the phenomena occurring during the thermomechanical treatment of metals was validated on commercially pure copper and selected multiphase steel.

Enhancing strength-ductility synergy of materials has been for decades an objective of research on structural metallic materials. It has been shown by many researchers that significant improvement of this synergy can be obtained by tailoring heterogeneous multiphase microstructures. Since large gradients of properties in these microstructures cause a decrease of the local fracture resistance, the objective of research is to obtain smoother gradients of properties by control of the manufacturing process. Advanced material models are needed to design such microstructures with smooth gradients. These models should supply information about distributions of various microstructural features, instead of their average values. Models based on stochastic internal variables meet this requirement. Our objective was to account for the random character of the recrystallization and to transfer this randomness into equations describing the evolution of dislocations and grain size during hot deformation and during interpass times. The idea of this stochastic model is described in the paper. Experiments composed of uniaxial compression tests were performed to supply data for the identification and verification of the model in the hot deformation and static recrystallization parts. Histograms of the grain size were measured after hot deformation and at different times after the end of deformation. Identification and validation of the model were performed. The validated model, which predicts evolution of heterogeneous multiphase microstructure, is the main output of our work. The model was implemented in the finite element program for hot rolling of plates and sheets and simulations of these processes were performed. The model’s capability to compare and evaluate various rolling strategies are demonstrated in the paper.