HVAF (High Velocity Air Flame) flame spraying can generate supersonic high-temperature gas jets, enabling thermal spraying at unprecedented speeds. However, there is a problem with the energy cost of this device. This study focused on combustors that used cheap liquid fuel (kerosene) as the fuel for HVAF. In this research, we have developed a compact combustor with a narrow channel as a heat source for the HVAF heat atomizer. Using this combustor, the stability of the flame formed in the combustor, the morphology of the flame, and the temperature behavior in the combustion chamber were investigated in detail. As a result, the magnitude of the swirling airflow had a great influence on the structure of the flame formed in the combustor, and the stable combustion range of the combustor could be determined. As the swirling air flow rate changes, the equivalent ratio of the entire combustor changes significantly, and the flame structure also transition from the premixed flame to the diffusi... [more]

Shunbei Oilfield is characterized by substantial heterogeneity and a complex oil−water relationship. The water-oil interface is dynamically changing, and it is a crucial parameter for reserve calculation and evaluation. The main purpose is to analyze the effect of fluid flow in multi-scale media on the water-oil interface. It is well known that the fracture-cavity reservoirs have well-developed fractures and karst caves, and their distribution is complex in Shunbei Oilfield. This paper presents a way to simplify the fracture-cavity system first, then uses a unit of oil wells as a system to study the water-oil interface, which avoids impact on the water-oil interface due to oil production. A detailed step by step procedure for solving the semi-analytical solution of water-oil interface in a fracture-cavity reservoir by using an explicit algorithm and a successive steady-state method is presented. The solution can be used to investigate water-oil interface behavior. In this paper, we val... [more]

The nature of carbonate deposition as well as diagenetic processes can cause the development of unique geological features such as cavities, vugs and fractures. These are called karsts. Encountering karsts while drilling can lead to serious consequences such as severe mud losses, drops of bottom hole assembly and gas kicks. To improve drilling safety in intervals of karstification, it is important to detect karsts as early as possible, preferably in advance. In this paper, we review methods and technologies that can be used for the prediction and early detection of karsts. In particular, we consider acoustic, resistivity, seismic and drilling-data methods. In addition to the inventions and technologies developed and published over the past 40 years, this paper identifies the advantages, limitations and gaps of these existing technologies and discusses the most promising methods for karst detection and prediction.

In recent years, the role of digital enterprises in the global economy has been growing. The issue of assessing their impact on social aspects is noticeable. The aim of the article is to show social impact as a key factor in the development of digital business models. The Analytic Hierarchy Process (AHP) method used and the criteria for social impact assessments based on heuristic methods allowed for the components of business models that relate to social impact to be ranked, and subsequently for socially oriented enterprises functioning in the digital economy to be ranked. The companies selected for the research are understood by the authors as digital business models, the concept of which is embedded in a pro-social management intention. Purposive sampling, which in this situation was considered to be the most effective in terms of the objective of the paper, was applied. The literature review, analyses and heuristic research have demonstrated that the social factor in modern applica... [more]

New technologies reaching out for meeting the needs of an aging population in developed countries have given rise to the development and gradual implementation of the concept of an autonomous vehicle (AV) and have even made it a necessity and an important business paradigm. However, in parallel, there is a discussion about consumer preferences and the willingness to pay for new car technologies and intelligent vehicle options. The main aim of the study was to analyze the impact of selected factors on the perception of the future of autonomous cars by respondents from the area of Southeastern Poland in terms of a comparison with traditional cars, with particular emphasis on the advantages and disadvantages of this concept. The research presented in this study was conducted in 2019 among a group of 579 respondents. Data analysis made it possible to identify potential advantages and disadvantages of the concept of introducing autonomous cars. A positive result of the survey is that 68% of... [more]

This paper presents the results of a study conducted to determine the dynamic power of a hydraulic leg. The hydraulic leg is the basic element that maintains the position of a powered roof support. It is located in the structure between the canopy and the floor base. The analysis assumes that its power must be greater than the energy of the impact of the rock mass. The energy of the rock mass is generated by tremors caused mainly by mining exploitation. The mining and geological structure of the rocks surrounding the longwall complex also have an influence on this energy generation. For this purpose, stationary tests of the powered roof support were carried out. The analysis refers to the space under the piston of the leg, which is filled with fluid at a given pressure. The bench test involved spreading the leg in the test station under a specified pressure. It was assumed that the acquisition of dynamic power would be at the point of pressure and increase in the space under the piston... [more]

Advances in remote data acquisition techniques have contributed to the flooding of society with spatial data sets and information. Widely available spatial data sets, including digital terrain models (DTMs) from aerial laser scanning (ALS) data, are finding more and more new applications. The article analyses and compares the heights of the 14 highest peaks of the Polish Carpathians derived from different data sources. Global navigation satellite system (GNSS) geodetic measurements were used as reference. The comparison primarily involves ALS data, and selected peaks’ GNSS measurements carried out with Xiaomi Mi 8 smartphones were also compared. Recorded raw smartphone GNSS measurements were used for calculations in post-processing mode. Other data sources were, among others, global and local databases and models and topographic maps (modern and old). The article presents an in-depth comparison of Polish and Slovak point clouds for two peaks. The results indicate the possible use of la... [more]

A fluidic oscillator with a bent outlet nozzle was investigated to find the effects of the bending angle on the characteristics of the oscillator with and without external flow. Unsteady aerodynamic analyses were performed on the internal flow of the oscillator with two feedback channels and the interaction between oscillator jets and external flow on a NACA0015 airfoil. The analyses were performed using three-dimensional unsteady Reynolds-averaged Navier-Stokes equations with a shear stress transport turbulence model. The bending angle was tested in a range of 0−40°. The results suggest that the jet frequency increases with the bending angle for high mass flow rates, but at a bending angle of 40°, the oscillation of the jet disappears. The pressure drop through the oscillator increases with the bending angle for positive bending angles. The external flow generally suppresses the jet oscillation, and the effect of external flow on the frequency increases as the bending angle increases.... [more]

The aim of this study was to identify the factors inducing customers to choose cashless payments made with payment cards at retail and service outlets during the COVID-19 pandemic. We identified factors that are crucial for consumers’ functioning under pandemic conditions, but which have so far been neglected in research. The estimated logit model indicates that the variables significantly influencing the more frequent choice of payment cards at retail outlets are related to the fear of infection and perception of the advantages of new technological solutions in connection with social distancing. Our study shows that, in addition to sociodemographic characteristics such as age and level of education, emotionally motivated factors induced by the pandemic have begun to play an important role in the transition to cashless payment.

The influence of lighting on crime was investigated by considering the effect of ambient light level on crimes recorded in three US cities for the ten-year period 2010 to 2019. Crime counts were compared for similar times of day, before and after the biannual clock change, therefore employing an abrupt change of light level but without an obvious intervention such as improving road lighting in an area. The results suggest a significant increase in robbery during darkness, confirming previous studies. The results also suggest darkness leads to an increase in arson and curfew loitering offenses, and to a decrease in disorderly conduct, family offences (non-violent) and prostitution. Future research investigating the effectiveness of improved street lighting should consider that this may not be beneficial for all types of crime.

Sound localization is a vast field of research and advancement which is used in many useful applications to facilitate communication, radars, medical aid, and speech enhancement to but name a few. Many different methods are presented in recent times in this field to gain benefits. Various types of microphone arrays serve the purpose of sensing the incoming sound. This paper presents an overview of the importance of using sound localization in different applications along with the use and limitations of ad-hoc microphones over other microphones. In order to overcome these limitations certain approaches are also presented. Detailed explanation of some of the existing methods that are used for sound localization using microphone arrays in the recent literature is given. Existing methods are studied in a comparative fashion along with the factors that influence the choice of one method over the others. This review is done in order to form a basis for choosing the best fit method for our us... [more]

This paper presents the concept of one possible but unconventional implementation of a Low Pressure Tube Transport (LPTT) system for a network with station-to-station distances of 300 km, based on the use of circular tunnels in which modular vehicles consisting of three interconnected functional segments move on wheels with airless tires. The physical limitations associated with high-speed vehicle travel in tunnels are presented. The reasons for the expected inconvenience in the travel system, compensated by short travel times, are justified. Assumptions for the use of locomotion, safety, and passenger segments in the construction of a vacuum modular vehicle are presented, as well as systems to ensure the efficient conversion of serial traffic in tunnels to parallel traffic in station areas. Schemes of station construction and traffic organization in the station area are presented, as well as assumptions for a number of systems increasing the safety of vehicle traffic used in emergency... [more]

Lighting uniformity is a key factor in traffic safety, and it could even result in energy savings for light installations. However, highly uniform horizontal road lighting for motorized vehicles may not be optimal for pedestrian roads. Therefore, it is important to evaluate the way in which pedestrians experience road lighting uniformity. Accordingly, we employed a qualitative approach to examine pedestrian road lighting uniformity. Visual analyses were used to exemplify and discuss the perceived uniformity. The case studies were performed on three pedestrian roads with similar light installations. The results show that the experience of road lighting uniformity differs substantially between the three roads. Based on the case studies, there are many aspects that need to be considered beyond the light falling on the horizontal surfaces. This study suggests that the visual experience of road lighting uniformity for pedestrians is difficult to estimate with photometric values because the... [more]

For many institutions, it is important to evaluate a given driving technique as safe or unsafe based on measurable vehicle movement parameters. The paper constitutes a part of studies aimed at establishing a method of parameter-based evaluation of drivers in various road conditions, in other words, to create a so-called ‘driver profile’. The tests were carried out on a 650 km route, on four varying road types. Longitudinal and lateral acceleration values are used to evaluate the driving style. An analysis is presented of the impact of the type and shape of road on acceleration values. The results demonstrate that the same driver, when driving the same vehicle on an expressway, an inter-urban road or in urban traffic, will move with various acceleration values. A detailed analysis of acceleration values and distributions was conducted. Interesting conclusions were drawn after excluding the so-called ‘smooth driving’ sections, by acceleration ranges of −0.5 to 0.5 m/s2 from the analysis.... [more]

The efficiency of a skid-steer, all-wheel drive, multiple-axle vehicle with a hydrostatic drivetrain equipped with low-speed motors when it operates on soft terrain was studied. A flow divider enables a single pump to simultaneously power more than one motor circuit with different pressures in each. It prevents kinematic discrepancy and improves vehicle mobility. There are two types of flow divider: spool type and gear type, where each type has its own set of performance characteristics, such as flow range, pressure drop, accuracy and application parameters. In the present work, the influence of the characteristics of both types of flow divider on overall vehicle driveline efficacy is described.

This paper is an evaluation of the common macro-economic, micro-economic, and social factors affecting households’ financial situations. Moreover, the author’s objective was to develop a fuzzy logic model for forecasting fluctuations in the number of nonperforming consumer loans in a country using the example of Poland. This study represents one of the first attempts in the global literature to develop such a forecasting model based on macro-economic factors. The findings confirm the usefulness of the proposed innovative approach to forecasting the volume of household insolvencies in a country.

This work discusses the results of a study of the influence of rates of change of confining pressure on the result of a drained compressibility tests intended to determine the modulus of compressibility of a rock skeleton Ks. A series of cyclical compressibility tests was performed on samples of sandstone soaked in kerosene, for various rates of compression and decompression of the pressure liquid filling the cell and the pore volume of the sample. The studies showed that the deformability of the tested sample was directly proportional to the rate of change of the confining pressure. As a consequence, the value of the Ks modulus and Biot coefficient α decreased with increasing sample load rate. This phenomenon should be attributed primarily to equilibration of the liquid pressure inside the high-pressure cell with the liquid pressure in the sample pore space, caused by filtration of the pore liquid. These phenomena prove that the filtration process impacts the values of the modulus of... [more]

The rapid growth of Central European economies has been related to inward FDI, so these countries are often regarded as dependent market economies. What is interesting in this context is the international expansion of some domestic-owned manufacturing companies from Central Europe. Looking through the lens of global production networks (GPN) and evolutionary resilience perspectives, the paper aims to identify paths and mechanisms of development of new multinational companies, namely Polish automotive firms expanding from around 2010 onwards in the global markets through acquisitions and greenfield investments in Western Europe, North America, and Asia. The authors ponder on the underlying motives and barriers of this process, the capabilities, and features of Polish-owned companies. In order to do it, both qualitative (13 interviews with representatives of new multinationals and the other stakeholders preceded by content analysis of various documents, including company annual reports i... [more]

The occurrence of surface discontinuous deformations in post-mining areas is currently a significant and important problem, due to both the frequency of their occurrence and the threat they pose to public safety. This paper presents the results of research concerning the possibility of sinkhole formation in the areas of abandoned mining excavations. For the purpose of assessing the condition of the rock mass disturbed by the existence of numerous mining excavations, electrical resistivity tomography investigations were carried out for the selected area where mining was undertaken in the past at shallow depths and many underground workings accessing the deposit exist. The sinkhole hazard was also analysed theoretically with a new original model based on the solution of A. Sałustowicz’s pressure arch theory.

The paper presents the preliminary results on the development of an integrated stripline-based microwave-microfluidic module. The measurements were performed in a frequency range from 300 MHz up to 12 GHz, with the microchannel filled with three different test fluids—deionized water, the ethanol-water solution and pure ethanol. Due to the higher-than-expected losses in transmittance, the selected module was examined with use of the cross-sections taken along its length. The possible causes were highlighted and described. Likewise, the proposed areas of further investigations have been clearly described.

The cumulative displacement-time curve is the most common and direct method used to predict the deformation trends of landslides and divide the deformation stages. A new method based on the inverse logistic function considering inverse distance weighting (IDW) is proposed to predict the displacement of landslides, and the quantitative standards of dividing the deformation stages and determining the critical sliding time are put forward. The proposed method is applied in some landslide cases according to the displacement monitoring data and shows that the new method is effective. Moreover, long-term displacement predictions are applied in two landslides. Finally, summarized with the application in other landslide cases, the value of displacement acceleration, 0.9 mm/day2, is suggested as the first early warning standard of sliding, and the fitting function of the acceleration rate with the volume or length of landslide can be considered the secondary critical threshold function of lands... [more]

The paper presents the novel use of analytical models of a beam on an elastic foundation. The one-parameter model (Winkler model) and the two-parameter models (Filonenko-Borodich and Pasternak models) were investigated. These models were used to describe the elastic response of axially loaded blind rivets used with sandwich structures. The elastic response related to the elastic strain energy is mentioned in the paper as the resilience modulus of the connection. The databases from laboratory pull-out tests were used to verify these models. One type of blind rivet (aluminum, with three clamping arms) and one type of sandwich beam were used. The sandwich beams used in the experiments consisted of two thin-walled and stiff external facings (zinc-coated steel) and a thick, soft core (polyisocyanurate foam—PIR). In the test the sandwich beams were subjected to static, axial pull-out loading. The research provides the quantitative comparison between the laboratory experiment and the analytic... [more]

A natural radioactivity in thermal water was investigated based on 19 selected thermal waters from Poland. The analysed results show that the radionuclides’ concentrations in the study waters vary over a wide range. The temperature of the waters varies from above 20 °C to above 80 °C. The waters are characterised by different mineralisation, chemical compositions, and belong to different hydrochemical types. There is a good correlation between the water temperature and the depths of the aquifer formations occurrence, suggesting the thermal energy originates from the thermal geogradient. The concentration of radium is well correlated with the water mineralisation. The ratio of radium activity (226Ra/228Ra) in groundwater relates not only the ratio of uranium activity to that of thorium (238U/232Th) in aquifer formation, but also depends on the physical and chemical water properties. Based on the concentration of radon and its transport model, the radiation exposures due to inhalation of... [more]

Energy expenditure is a critical characteristic in evaluating the flight performance of flying insects. To investigate how the energy cost of small-sized insects varies with flight speed, we measured the detailed wing and body kinematics in the full speed range of fruitflies and computed the aerodynamic forces and power requirements of the flies. As flight speed increases, the body angle decreases and the stroke plane angle increases; the wingbeat frequency only changes slightly; the geometrical angle of attack in the middle upstroke increases; the stroke amplitude first decreases and then increases. The mechanical power of the fruitflies at all flight speeds is dominated by aerodynamic power (inertial power is very small), and the magnitude of aerodynamic power in upstroke increases significantly at high flight speeds due to the increase of the drag and the flapping velocity of the wing. The specific power (power required for flight divided by insect weigh) changes little when the adv... [more]

To study the plasma plume expansion dynamics of nanosecond laser ablating Al/PTFE, the Al/PTFE propellant was prepared by a molding sintering method and the rapid expansion process of the plasma plume was photographed using fast photography technology. The effects of the proportion of Al, laser energy and ambient pressure on plasma plume expansion dynamics are analyzed. The results show that the plume expansion process of laser ablating Al/PTFE plasma can be divided into three stages and this phenomenon has not been reported in the literature. The Al powder doped in PTFE will block part of the laser transmission into the propellant, thus reducing the laser absorption depth of the propellant. In the case of short pulse laser ablation, the reaction rate between Al and PTFE is optimal when the reductant is slightly higher than the oxidant. As the laser energy increases, the light intensity of the plasma becomes stronger, the plasma size becomes larger and the existence time of plasma beco... [more]