The use of artificial intelligence (AI) in companies is advancing rapidly. Consequently, multidisciplinary research on AI in business has developed dramatically during the last decade, moving from the focus on technological objectives towards an interest in human users’ perspective. In this article, we investigate the notion of employees’ trust in AI at the workplace (in the company), following a human-centered approach that considers AI integration in business from the employees’ perspective, taking into account the elements that facilitate human trust in AI. While employees’ trust in AI at the workplace seems critical, so far, few studies have systematically investigated its determinants. Therefore, this study is an attempt to fill the existing research gap. The research objective of the article is to examine links between employees’ trust in AI in the company and three other latent variables (general trust in technology, intra-organizational trust, and individual competence trust).... [more]

This paper presents the effect of a composite poly(3,4-ethylenedioxythiophene) polystyrene sulfonate PEDOT:PSS and copper-doped nickel oxide (Cu:NiOx) hole transport layer (HTL) on the performance of perovskite solar cells (PSCs). Thin films of Cu:NiOx were spin-coated onto fluorine-doped tin oxide (FTO) glass substrates using a blend of nickel acetate tetrahydrate, 2-methoxyethanol and monoethanolamine (MEA) and copper acetate monohydrate. The prepared solution was stirred at 65 °C for 4 h and spin-coated onto the FTO substrates at 3000 rpm for 30 s in a nitrogen glovebox. The Cu:NiOx/FTO/glass structure was then annealed in air at 400 °C for 30 min. A mixture of PEDOT:PSS and isopropyl alcohol (IPA) (in 1:0.05 wt%) was spun onto the Cu:NiOx/FTO/glass substrate at 4000 rpm for 60 s. The multilayer structure was annealed at 130 °C for 15 min. Subsequently, the perovskite precursor (0.95 M) of methylammonium iodide (MAI) to lead acetate trihydrate (Pb(OAc)2·3H2O) was spin-coated at 4000... [more]

The dynamic characteristics of hydropower unit governing systems considerably influence the stability of hydropower units and the connected power system. The dynamic performances of hydropower units with power regulation mode (PRM) and opening regulation mode (ORM) are different. This paper establishes a detailed linear model of a hydropower unit based on the Phillips−Heffron model. The damping characteristic and stability of two regulation modes with different water inertia time constants TW were analyzed. ORM tended to provide negative damping, while PRM often provided positive damping in the major parts of the frequency range within the normal frequency oscillations when TW was large. Eigenvalue analysis illustrated that PRM has better stability than ORM. To validate the analysis, a simulation under two typical faults WAS conducted based on a nonlinear model of a hydropower unit. The simulation results illustrated that the responses of units with PRM are more stable in terms of impo... [more]

Energy efficiency in the building industry is related to the amount of energy that can be saved through thermal improvement. Therefore, it is important to determine the energy saving potential of the buildings to be thermally upgraded in order to check whether the set targets for the amount of energy saved will be reached after the implementation of corrective measures. In real residential buildings, when starting to make energy calculations, one can often encounter the problem of incomplete architectural documentation and inaccurate data characterizing the object in terms of thermal (thermal resistance of partitions) and usable (number of inhabitants). Therefore, there is a need to search for methods that will be suitable for quick technical analysis of measures taken to improve energy efficiency in existing buildings. The aim of this work was to test the usefulness of the type Takagi-Sugeno fuzzy models of inference model for predicting the energy efficiency of actual residential bui... [more]

Air-core coil current transformer is a key piece of equipment in the digital substation development. However, it is more vulnerable to various faults when compared with the traditional electromagnetic current transformer. Aiming at understanding the effect of various parameters on the performance of the air-core coil current transformer, this paper investigates the influence of these factors using the maximum information coefficient. The interference mechanism of influencing factors on the transformer error is also analyzed. Finally, the Stacking model fusion algorithm is used to predict transformer errors. The developed base model consists of deep learning, integrated learning and traditional learning algorithms. Compared with gated recurrent units and extreme gradient boosting algorithms, the prediction model based on stacking model fusion algorithm proposed in this paper features higher accuracy and reliability which helps improve the performance and safety of future digital substat... [more]

The amount of heat lost through the envelope of a building is one of the most important variables that affects the energy performance evaluation of a house. In addition, it is especially important to estimate and accurately diagnose the amount of heat produced by windows. In Korea, windows’ U-values reflect a building’s initial design values and thermal characteristics that determine the thermal performance of an existing building, and is a factor that can overestimate the energy performance of a building. Therefore, there is a need for a field measurement method that can accurately measure the total U-value of windows in an existing house. This study provides a method of quantitatively measuring the total U-value of windows using the infrared (IR) method in ISO 9869-2. As a result of measuring the U-value using the infrared (IR) method, the Korean Standard (KS F 2278) for window performance test result values and the root mean square error (cvRMSE) for the U-value measurements using t... [more]

When performing AC/DC-DC/AC power conversions, multilevel converters provide several advantages as compared to classical two-level converters. This paper deals with the dynamic modeling, control, and robustness assessment of multilevel flying-capacitor converters. The dynamic model is derived using the Power-Oriented Graphs modeling technique, which provides the user with block schemes that are directly implementable in the Matlab/Simulink environment by employing standard Simulink libraries. The performed robustness assessment has led to the proposal of a divergence index, which allows for evaluating the voltage balancing capability of the converter using different voltage vector configurations for the extended operation of the converter, namely when the number of output voltage levels is increased for a given number of capacitors. A new variable-step control algorithm is then proposed. The variable-step control algorithm safely enables the converter extended operation, which prevents... [more]

Defining distinctive areas of the physical properties of rocks plays an important role in reservoir evaluation and hydrocarbon production as core data are challenging to obtain from all wells. In this work, we study the evaluation of lithofacies values using the machine learning algorithms in the determination of classification from various well log data of Kazakhstan and Norway. We also use the wavelet-transformed data in machine learning algorithms to identify geological properties from the well log data. Numerical results are presented for the multiple oil and gas reservoir data which contain more than 90 released wells from Norway and 10 wells from the Kazakhstan field. We have compared the the machine learning algorithms including KNN, Decision Tree, Random Forest, XGBoost, and LightGBM. The evaluation of the model score is conducted by using metrics such as accuracy, Hamming loss, and penalty matrix. In addition, the influence of the dataset features on the prediction is investig... [more]

Wind power prediction (WPP) of wind farm clusters is important to the safe operation and economic dispatch of the power system, but it faces two challenges: (1) The dimensions of the input parameters for WPP of wind farm clusters are very high so that the input parameters contain irrelevant or redundant features; (2) it is difficult to build a holistic WPP model with high-dimensional input parameters for wind farm clusters. To overcome these challenges, a novel short-term WPP model for wind farm clusters, based on sequential floating forward selection (SFFS) feature selection and bidirectional long short-term memory (BLSTM) deep learning, is proposed in this paper. First, more than 300,000 input features of the wind farm cluster are constructed. Second, the SFFS method is applied to sort the high-dimensional features and analyze the rule that the forecasting accuracy changes with the number of features to obtain the optimal number of features and feature sets. Finally, based on the res... [more]

Electroporation is a phenomenon that consists of increasing the permeability of the cell membrane by means of high-intensity electric field application. Nowadays, its clinical application to cancer treatment is one of the most relevant branches within the many areas of electroporation. In this area, it is essential to apply homogeneous treatments to achieve complete removal of tumors and avoid relapse. It is necessary to apply an optimized transmembrane potential at each point of the tissue by means of a homogenous electric field application and appropriated electric field orientation. Nevertheless, biological tissues are composed of wide variety, heterogeneous and anisotropic structures and, consequently, predicting the applied electric field distribution is complex. Consequently, by applying the parallel-needle electrodes and single-output generators, homogeneous and predictable treatments are difficult to obtain, often requiring several repositioning/application processes that may l... [more]

This paper discusses the question of heat flux distribution between bristle package and rotor during a rubbing event. A three-dimensional Computational Fluid Dynamics (3D CFD) model of the brush seal test rig installed at the Institute of Thermal Turbomachinery (ITS) was created. The bristle package is modelled as a porous medium with local non-thermal equilibrium. The model is used to numerically recalculate experimentally conducted rub tests on the ITS test rig. The experimentally determined total frictional power loss serves as an input parameter to the numerical calculation. By means of statistical evaluation methods, the ma in influences on the heat flux distribution and the maximum temperature in the frictional contact are determined. The heat conductivity of the rotor material, the heat transfer coefficients at the bristles and the rubbing surface were identified as the dominant factors.

In the 21st century, it is becoming increasingly clear that human activities and the activities of enterprises affect the environment. Therefore, it is important to learn about the methods in which companies minimize the negative effects of their activities. The article presents the steps taken and innovative actions carried out by enterprises in the energy sector. The article analyzes innovative activities undertaken and implemented by enterprises from the energy sector. The relationships between innovative strategies, including, inter alia, digitization, and Industry 4.0 solutions, in the development of companies and the achieved results concerning sustainable development and environmental impact. Digitization has far exceeded traditional productivity improvement ranges of 3−5% per year, with a clear cost improvement potential of well above 25%. Enterprises on a large scale make attempts to increase energy efficiency by implementing the state-of-the-art innovative technical and techn... [more]

The rising demand for lower noise emissions of car ancillary units due to electrification and higher customer expectations regarding driving comfort results in the need for more silent car components. Hydraulic driven car components in particular are often identified as a major source of noise in the system. Therefore, it is mandatory to investigate the noise sources inside the hydraulic system. In this work, a combined CFD-FEM approach is applied to estimate the flow-induced noise radiation of a mechanically driven transmission pump. To achieve this goal, the mapping procedure to hand over the pressure field from the CFD to the FEM mesh must be valid. For this purpose, the error during the mapping process is evaluated and different parameters, which influence the mapping results, are analyzed. Additionally, the impact of the time step size and the length of the time signal on the frequency resolution of the force signal is investigated to get an appropriate excitation force for the vi... [more]

New types of power system transients with lower time constants are emerging due to the replacement of synchronous generation with converter interfaced generation and are challenging the modeling approaches conventionally applied in power system simulation. Quasi-stationary simulations are based on classical phasor models, whereas EMT simulations calculate the instantaneous values of models in the time domain. In addition to these conventional modeling approaches, this paper investigates simulation based on dynamic phasor models, as has been proposed by the Shifted Frequency Analysis. The simulation accuracy of the three modeling approaches was analyzed for characteristic transients from the electromagnetic to the electromechanical phenomena range, including converter control as well as low inertia transients. The analysis was carried out for systems with converter interfaced and synchronous generation whilst considering the simulation step size as a crucial influence parameter. The res... [more]

Based on the general theory of fractional order derivatives and integrals, application of the Caputo−Fabrizio operator is analyzed to improve a mathematical model of a two-mass system with a long shaft and concentrated parameters. Thus, the real transmission of complex electric drives, which consist of long shafts with a sufficient degree of adequacy, is presented as a two-mass system. Such a system is described by ordinary fractional order differential equations. In addition, it is well known that an elastic mechanical wave, propagating along a drive transmission with a long stiff shaft, creates a retardation effect on distribution of the time−space angular velocity, the rotation angle of the shaft, and its elastic moment. The approach proposed in the current work helps to take in account the moving elastic wave along the shaft of electric drive mechanism. On this basis, it is demonstrated that the use of the fractional order integrator in the model for the elastic moment enables it t... [more]

Gears are common and important components of many types of propulsion systems applied in mechanical engineering. The aim of this paper is to present the mechanical design and performance analysis of a novel two-stage magnetic precession gear (MPG). The main advantage of the proposed design is the ability to obtain higher transmission ratios than other currently known magnetic gear types. A detailed analysis of the performance of the MPG was carried out employing a developed numerical model of the magnetic field in the proposed gear. The MPG model is based on the finite element method (FEM) and allows determining the relations between the torque acting on the main components of the gear, load angles, and air-gap lengths. To validate the developed FEM model, the prototype of an MPG with a 1/144 gear ratio was built and tested. The experiments were also focused on determining the mechanical efficiency as well as the influence of rotational speed and lengths of air gaps on the maximum load... [more]

Protection of marine environment and reduction of GHG emissions are currently imperative criterion for ship design. For ships in service, including fishing vessels powered by internal combustion engines, options of retrofitting are sought to reduce their hydrodynamic resistance and fuel consumption. One such possibility is the addition of a simple-shape bulbous bow, which can be installed at low cost to upgrade a fishing vessel. We present an analysis of the effect that the bulbous bow has on fishing vessel resistance across the whole range of speeds at which the entire work cycle of the vessel is carried out. The resistance was calculated using a calculation of fluid dynamics (CFD) method for the actual size of the vessel. We show that it is possible to develop such a bulbous bow for which the resistance of fishing vessel with a bulbous bow is going to be lower than that of an unmodified shape. For the modified shape of the fishing vessel, fuel consumption, amount and composition of e... [more]

In this article, the method of hard rock mining by undercutting or back incision using asymmetrical disk tools as an alternative to the milling method with the use of cutting tools was described. The results of modelling the penetration of a single asymmetric disk tool edge into an artificial and natural rock sample were presented and compared with empirical laboratory tests. The effect of stand tests for mining artificial rock samples using asymmetrical disk tools mounted on the rotating plate was presented. The tests were carried out on two unique test stands. The solution of an innovative mining head with a complex motion trajectory, using the asymmetrical disk tools, was presented. The innovative mining head especially developed at the AGH Kraków Department of Machinery Engineering and Transport for roadheaders, was presented. The results of preliminary field tests with the use of this mining head were also described.

This paper presents MARTINE (Multi-Agent based Real-Time INfrastruture for Energy), a simulation, emulation and energy management platform for the study of problems related to buildings and smart grids. Relevant advances related to buildings and smart grid management and operation have been proposed, focusing either on software models for decision support or on physical infrastructure and control approaches. These two perspectives are, however, complementary, and no practical assessment can be achieved without a suitable interaction and analysis of the impact that decision-making models have on physical resources, and vice-versa. MARTINE overcomes this limitation by integrating, in a single platform: real buildings with the associated devices and resources; emulated components that complement the ones present in the buildings; simulated resources, players and buildings using multi-agent systems, real-time simulation with hardware in the loop capabilities, which enables integrating virt... [more]

Three connection methods for the combined heating systems of a closed-type heat-source tower heat pump (CHTHP) and solar collector (SC) were proposed in this paper: the heat-source tower (HST) and solar collector were connected in series (HST+SC), and the solar collector and heat pump (HP) condenser were connected in series (SC+HP) and in parallel (SC//HP). The calculation module of the closed heat-source tower was built using programming software based on C++ language, and three corresponding calculation models of the combined heating systems were established in the TRNSYS. Under the climatic conditions of the cold season in Changsha, the combined heating performance of the three systems was simulated and analyzed. The results indicate that the simulation results of the established models are in good agreement with the test results, and the simulation results can be used for the research of the system’s combined heating performance. When the outdoor air temperature and solar radiation... [more]

The article presents the possibility of using the currents’ physical components (CPC) theory to generate the reference current of the active power filter (APF). The solution proposed by the authors is based on the cooperation of minimizing balancing compensators (MBC), which, due to their use in 4-wire systems, have been divided into two structures. The first compensator, which purpose is to minimize and balance the reactive current and the unbalanced current of the zero sequence, is built in the star system (STAR-MBC). The purpose of the second compensator, which operation occurs in the delta system (DELTA-MBC), is to minimize and balance the other two components, i.e., the unbalanced current of the negative sequence and the unbalanced current of the positive sequence. The two structures cooperating with each other significantly reduce the currents associated with the reactive elements, i.e., reactive current, and the unbalanced current. As mentioned, these currents are reduced but no... [more]

A theoretical model was developed to investigate a falling-film absorber on horizontal tubes with an aqueous alkaline nitrate solution as working fluid. The absorbent, composed of an aqueous solution of nitrates (Li, K, Na) in salt mass percentages of 53%, 28%, and 19% respectively, offers favourable thermal stability, corrosiveness, and heat and mass transfer conditions which can be appropriate for absorption cooling cycles driven by high-temperature heat sources. The mathematical model developed characterises the heat and mass transfer processes and the flow regime effect (droplet-formation, droplet-fall, and falling-film) on the falling-film absorber. The results show the importance of the falling-film and droplet-formation flow regimes in the absorption process. The solution temperature and concentration profiles inside the absorber were established together with their values at the exit. The results obtained by the theoretical model were well in agreement with the experimental dat... [more]

Electric Vehicles (EVs) are becoming increasingly available and are expected to be a large part of the load in future power systems. EV chargers are a relatively new type of load and are mainly interfaced with the grid through power electronics. It is therefore important to investigate the impact they have on power system dynamic behaviour. In this paper, two detailed EV charger models (representing a typical slow and fast charger) were investigated. The aim was to test the capability of standard static—and more importantly, dynamic—load models, commonly used in power system studies, to represent the static and dynamic behaviour of EV chargers. Different control parameter settings for two types of EV chargers were investigated, as were the limits of standard power system dynamic load model structures’ accurate representation. Typical parameter sets have also been provided for cases where proper representation was possible.

There has been a gradual increase in the field of parts recovery from cars that are withdrawn from use. However, the disposal of automotive shredder residue (ASR) still remains a significant problem. ASR is refuse derived fuel (RDF), which contains mainly plastics, fiber sponges, and rubbers in different proportions, and therefore a thermal treatment of selected waste samples is applied. The presented research includes thermogravimetry (TG) analysis and differential thermogravimetric (DTG) analysis, as well as a proximate and an ultimate analysis of the ASR samples. The obtained results were processed and used as an input for modelling. The numerical calculations focused on the identification of the ASR’s average composition, the raw pyrolysis process product, its dry pyrolytic gas composition, and the combustible properties of the pyrolytic gases. The TGA analysis with three heating rate levels covered the temperature range from ambient to 800 °C. The thermal decomposition of the stud... [more]

Requirements of modern process and power technologies for compact and highly efficient equipment for transferring large heat fluxes lead to designing these apparatuses as dense parallel flow systems, ranging from conventional to minichannel dimensions according to the specific industrial application. To avoid operating issues in such complex equipment, it is vital to identify not only the local distribution of heat flux in individual parts of the heat transfer surface but also the uniformity of fluid flow distribution inside individual parallel channels of the flow system. A composite modelling system is currently being developed for accurate design of such complex heat transfer equipment. The modeling approach requires a flow distribution model enabling to yield accurate-enough predictions in reasonable time frames. The paper presents the results of complex experimental and modeling investigation of fluid flow distribution in dividing headers of tubular-type equipment. Different model... [more]