Aforementioned Parameter Research Articles

SEAKEEPING PERFORMANCE OF A HYDROFOIL IN WAVES USING CFD APPROACH

Hydrofoil usually experiences high resistance and excessive vertical motions (heave and pitch) that may affect the passenger’s comfort due to the harsh environmental condition. Therefore, it is necessary to investigate seakeeping performance of a hydrofoil ship in waves due to the presence of a complex hydrodynamic phenomenon. To achieve this objective, an analysis of Computational Fluid Dynamic (CFD) approach on a hydrofoil ship motion is proposed. Several parameters such as Froude Number and foil angle of attack have been taken into account. The results revealed that the subsequent increase of Froude Number was inversely proportional to the heave and pitch motions. Inherently, these have led to an upgrade of hydrofoil seakeeping performances presented in the form of high Response Amplitude Operators (RAO). Furthermore, the increasing angle of the foil bow was proportional to the heave motion while for the foil stern, 7.5o showed lower heave motion, then followed by 5o and 10o respectively. For the pitch motion, the increase of foil bow was lower at 5o then followed by 10o and 7.5o. The increase of the foil stern was proportional to the pitch motion experiences by a hydrofoil. In general, this CFD simulation is very beneficial to ensure operational effectiveness of hydrofoil design in high sea states with respect to the aforementioned design parameter.

Investigating the Multifaceted Nature of Radiation-Induced Coagulopathies in a Göttingen Minipig Model of Hematopoietic Acute Radiation Syndrome.

Coagulopathies are well documented after acute radiation exposure at hematopoietic doses, and radiation-induced bleeding is notably one of the two main causes of mortality in the hematopoietic acute radiation syndrome. Despite this, understanding of the mechanisms by which radiation alters hemostasis and induces bleeding is still lacking. Here, male Göttingen minipigs received hematopoietic doses of 60Co gamma irradiation (total body) and coagulopathies were characterized by assessing bleeding, blood cytopenia, fibrin deposition, changes in hemostatic properties, coagulant/anticoagulant enzyme levels, and markers of inflammation, endothelial dysfunction, and barrier integrity to understand if a relationship exists between bleeding, hemostatic defects, bone marrow aplasia, inflammation, endothelial dysfunction and loss of barrier integrity. Acute radiation exposure induced coagulopathies in the Göttingen minipig model of hematopoietic acute radiation syndrome; instances of bleeding were not dependent upon thrombocytopenia. Neutropenia, alterations in hemostatic parameters and damage to the glycocalyx occurred in all animals irrespective of occurrence of bleeding. Radiation-induced bleeding was concurrent with simultaneous thrombocytopenia, anemia, neutropenia, inflammation, increased heart rate, decreased nitric oxide bioavailability and endothelial dysfunction; bleeding was not observed with the sole occurrence of a single aforementioned parameter in the absence of the others. Alteration of barrier function or clotting proteins was not observed in all cases of bleeding. Additionally, fibrin deposition was observed in the heart and lungs of decedent animals but no evidence of DIC was noted, suggesting a unique pathophysiology of radiation-induced coagulopathies. These findings suggest radiation-induced coagulopathies are the result of simultaneous damage to several key organs and biological functions, including the immune system, the inflammatory response, the bone marrow and the cardiovasculature.

Hedging and machine learning driven crude oil data analysis using a refined Barndorff-Nielsen and Shephard model

In this paper, a refined Barndorff-Nielsen and Shephard (BN-S) model is implemented to find an optimal hedging strategy for commodity markets. The refinement of the BN-S model is obtained with various machine and deep learning algorithms. The refinement leads to the extraction of a deterministic parameter from the empirical data set. The problem is transformed to an appropriate classification problem with a couple of different approaches — the volatility approach and the duration approach. The analysis is implemented to the Bakken crude oil data and the aforementioned deterministic parameter is obtained for a wide range of data sets. With the implementation of this parameter in the refined model, the resulting model performs much better than the classical BN-S model.

An Investigation Into the Effects of an Annular Gap on Surface Settlement

Ground displacement is an inevitable problem in the excavation of tunnels and underground spaces near the surface. The importance of surface settlement increases with a reduction of the depth of tunnelling. In urban areas, when settlements exceed the allowed value, they can damage surface and subsurface structures. Therefore, the identification of factors that affect settlements is critical. One of the essential factors is the grouting behind the segmental lining of a tunnel. An annular gap behind the segmental ring usually causes more problems such as surface settlement and displacement and damage to the precast concrete and unsuitable sealing. Void thickness has a large effect on the amount of maximum surface settlement and the shape of the surface settlement curve. This study focuses mainly on the effects of the aforementioned parameter on surface settlements. Both numerical and empirical methods were used in this study. In addition, the field data were presented in order to support the predicted surface settlements by 3D numerical modelling. The results obtained from the 3D numerical modelling were in agreement with the field measurements. The obtained results revealed that the amount of maximum surface settlement and shape of the surface settlement curve is strongly related to the annual gap thickness and the grouting operation.

Numerical Study of an Oscillating-Wing Wingmill for Ocean Current Energy Harvesting: Fluid-Solid-Body Interaction with Feedback Control

The performance and flow around an oscillating foil device for current energy extraction (a wingmill) was studied through numerical simulations. OpenFOAM was used in order to study the two-dimensional (2D) flow around a wingmill. A closed loop control law was coded in order to follow a reference angle of attack. The objective of this control law is to modify the angle of attack in order to enhance the lift force (and increase power extraction). Dimensional analysis suggests a compromise between the generator (or damper) stiffness and actuator/control gains, so a parametric study was carried out while using a new dimensionless number, called B, which represents this compromise. It was found that there is a maximum on the efficiency curve in terms of the aforementioned dimensionless parameter. The lessons that are learned from this fluid-structure and feedback coupling are discussed; this interaction, combined with the feedback dynamics, may trigger dynamic stall, thus decreasing the performance. Moreover, if the control strategy is not carefully selected, then the energy spent on the actuator may affect efficiency considerably. This type of simulation could allow for the system identification, control synthesis, and optimization of energy harvesting devices in future studies.

Efficient Generation of Different Topological Representations of Graphs Beyond-Planarity

Beyond-planarity focuses on combinatorial properties of classes of non-planar graphs that allow for representations satisfying certain local geometric or topological constraints on their edge crossings. Beside the study of a specific graph class for its maximum edge density, another parameter that is often considered in the literature is the size of the largest complete or complete bipartite graph belonging to it. Overcoming the limitations of standard combinatorial arguments, we present a technique to systematically generate all non-isomorphic topological representations of complete and complete bipartite graphs, taking into account the constraints of the specific class. As a proof of concept, we apply our technique to various beyond-planarity classes and achieve new tight bounds for the aforementioned parameter.

STABILITY ANALYSIS OF HYBRID ENERGY STORAGE BASED ON SUPERCAPACITOR AND BATTERY

The aim of the work is to analyze the stability of the battery-supercapacitor hybrid storage of power supply for resistance micro-welding equipment, considering the possible variation of the system parameters and taking into account parallel series resistance of the circuit components. Methodology. The sufficient accurate mathematical model of the hybrid energy storage system to stability analysis has been obtained by the state-space average method. According to the state-space averaging method, PWM switching converters are described by separate circuit topologies for each switching period. The system of differential equations for each time interval has been derived by use of the Kirchhoff rules. The small-signal model transfer function of the SEPIC converter has been obtained by applying the Laplace transform to linear state equations averaged over one switching cycle. Finally, the Nyquist stability criterion has been considered to evaluate the stability of the proposed energy storage system. Results. Bode diagrams of an open-loop system for different values of the duty cycle, average load current, and input voltage have been obtained by using MATLAB software. The gain margin ranges from 14.6 dB to 26.4 dB and the phase margin ranges from 45.4 degrees to 54.8 degrees. From these results, it is obvious that the proposed system meets the stability criteria regardless of the aforementioned parameter fluctuations. Originality. The high-efficiency energy storage system for micro resistance welding technology has been proposed. Developing of the energy storage system according to the battery semi-active hybrid topology enables to control the Li-ion battery discharge current within the maximum allowable value. SEPIC converter utilization ensures the high-efficient operation of the power supply despite the battery charge state. Moreover, this topology allows implementing series and parallel configuration of both batteries and supercapacitors to obtain the required value of voltage and current. Practical significance. The mathematical model of the SEPIC converter has been developed by applying the state-space averaging technique. The stability analysis for parameter variation, such as duty cycle and the average load current, the input voltage has been performed by using Nyquist criteria.

Study of the influence of crystalline phases on optical characteristics of a glass-ceramic in the visible range via simulations by the four-flux method

Opal glasses fabricated by Arc (Arques, France) are glass-ceramics that consist of a glassy matrix mainly constituted of silicon dioxide with well crystallized fluoride compounds as inclusions. These later (ca. 8 vol%) play the role of light scattering centers leading to the well-known milky feature of the commercialized glassware, dinnerware products. Their overall chromatic characteristics strongly depend on few parameters (e.g. the refractive indexes of the glass and the ceramic(s), the concentration of inclusions, their mean size, the surface roughness of the article, etc) that have to be determined and controlled during the manufacturing process to end at the product with the desired optical properties. Using a transfer matrix formalism, the 4-flux method can indeed be used to anticipate the transmittance and reflectance of an object for different set of parameters. The impact of each aforementioned parameter on the color rendering will be here separately discussed, and simulations will be confronted to experimental data to assert their validity and their interest to the genesis of new products with targeted optical properties.

Photovoltaic systems on dairy farms: Financial and renewable multi-objective optimization (FARMOO) analysis

The aim of this study was to develop a financial and renewable multi-objective optimization (FARMOO) method for dairy farms. Due to increased global milk production and European Union policies concerning renewable energy contributions, the optimization of dairy farms from financial and renewable standpoints is crucial. The FARMOO method found the optimal combination of dairy farm equipment and management practices, based on a trade-off parameter which quantified the relative importance of maximizing farm net profit and maximizing farm renewable contribution. A PV system model was developed and validated to assess the financial performance and renewable contribution of this technology in a dairy farming context. Seven PV system sizes were investigated, ranging from 2 kWp to 11 kWp. Multi-objective optimization using a Genetic Algorithm was implemented to find the optimal combination of equipment and management practices based on the aforementioned trade-off parameter. For a test case of a 195 cow spring calving dairy farm in Ireland, it was found that when the relative importance of farm net profit was high, a PV system was not included in the optimal farm configuration. When net profit and renewable contribution were of equal importance, the optimal farm configuration included an 11 kWp PV system with a scheduled water heating load at 10:00. Multi-objective optimization was carried out for the same test case with the goals of maximizing farm net profit and minimizing farm CO2 emissions. Under this scenario, the optimal farm configuration included an 11 kWp PV system when the relative importance of farm net profit was low. This study included a sensitivity analysis which investigated the use of a 40% grant aid on PV system capital costs. This sensitivity analysis did not significantly improve the financial feasibility of PV systems on dairy farms. Moreover, it was found that load shifting of a farm’s water heating enabled the majority of the PV system’s electricity output to be consumed. Hence the use of batteries with small PV systems on dairy farms may not be necessary. The method described in this study will be used to inform policy and provide decision support relating to PV systems on dairy farms.

Stone Matrix Asphalt (SMA) with Construction Waste and Curauá Fiber (Ananas erectifolius)

The SMA mixtures are characterized by a high void ratio, which favors binder draindown. In order to avoid this effect, fibers are added to the mixture, which in this case came from Curauá da Amazônia (Ananas erectifolius). The final composition studied resulted in 75% coarse aggregate, 15% fine aggregate, 10% filler, 0.3% of the Curauá fiber residue, and CAP contents equal to 6.50% and 6.88% for the formulations with SMA-Crushed Stone (reference) and SMA-construction and demolition waste (alternative), respectively. The results showed for the Tensile Strength that the composites with CDW reached higher results. The Resilient Modulus values presented small variations for the set of compositions in all loading levels at a temperature of 25°C. However, at a temperature of 40°C, the aforementioned parameter presented decreases in both researched formulations. In general, at all levels examined, higher results were observed for the alternative mixture (SMA-CDW). It is noteworthy the highest results of this parameter when comparing the compositions with the Curauá fiber residue and the formulations mentioned in the literature, with the presence of other types of fibers. Regarding the increase in temperature, there was a decrease in results for both mechanical parameters (TS, DM), but with lower losses for the SMA-RCD composition.

Settlements’ firewood consumption estimation based on geospatial modelling: a case study of the Republic of Georgia

ABSTRACT Many research methodologies aim to calculate forest resource and firewood consumption on the village, community, municipality, regional, and national levels. This parameter is vital for decision-makers in a number of areas, such as environmental protection, forest governance, energy, the economy, and disaster risk management and prevention. As a number of studies show, there is no alternative to heating with firewood in Georgian villages. This model uses a dataset for Georgia to facilitate the calculation of the aforementioned parameter for populated areas via PostGIS spatial analysis and statistical analysis of existing data. Elevations, degree-days, and firewood consumption rates were measured per capita and household for populated areas. The model determines the volume of firewood required for heating in rural settlements. The demand for firewood in each village can be calculated by the number of inhabitants. Settlements represent minor administrative units according to which firewood consumption on any administrative level, whether it be on regional or municipal levels, is defined.

Bayesian Model Averaging and Prior Sensitivity in Stochastic Frontier Analysis

This paper discusses Bayesian model averaging (BMA) in Stochastic Frontier Analysis and investigates inference sensitivity to prior assumptions made about the scale parameter of (in)efficiency. We turn our attention to the “standard” prior specifications for the popular normal-half-normal and normal-exponential models. To facilitate formal model comparison, we propose a model that nests both sampling models and generalizes the symmetric term of the compound error. Within this setup it is possible to develop coherent priors for model parameters in an explicit way. We analyze sensitivity of different prior specifications on the aforementioned scale parameter with respect to posterior characteristics of technology, stochastic parameters, latent variables and—especially—the models’ posterior probabilities, which are crucial for adequate inference pooling. We find that using incoherent priors on the scale parameter of inefficiency has (i) virtually no impact on the technology parameters; (ii) some impact on inference about the stochastic parameters and latent variables and (iii) substantial impact on marginal data densities, which are crucial in BMA.

Assessment of Power Quality Problems Using M-band Wavelet Packet Transform

The attention towards the quality of power supplied is increasing due to many factors. The deteriorated power supply results into large economic loss and loss of data. This has made the identification and solution of Power Quality (PQ) disturbances the stringent requirement of the day. Precise identification of such PQ disturbances helps us to plan the appropriate mitigation techniques. This article proposes an efficient technique for identification of various PQ disturbances using a statistical parameter Average Deviation and M-band Wavelet Packet Transform (M-band WPT). PQ disturbances as per IEEE 11592009 standard definition are simulated using MATLAB script files. Aforementioned statistical parameter is computed for each Mband WPT decomposition coefficient. Similar results are obtained using conventional Wavelet Packet Transform (WPT). At the end comparative study of the results of M-band WPT and WPT is done.

Optimization of Hetero-Gate-Dielectric Tunnel FET for Label-Free Detection and Identification of Biomolecules

In this article, for the first time, the performance of a double-hetero-gated-dielectric-modulated tunnel FET (DHGDM-TFET) biosensor device, having channel length ( ${L}_{\text{ch}}$ ) of 50 nm, is thoroughly investigated in terms of threshold voltage- ( ${V}_{\text {TH}}$ -), subthreshold swing- (SS-), ON-current- ( ${I}_{ \mathrm{\scriptscriptstyle ON}}$ -), and OFF-current- ( ${I}_{ \mathrm{\scriptscriptstyle OFF}}$ -) sensitivity parameters, in order to find its suitability in successful detection and identification of different biomolecules. The investigation is further extended to the optimization of the proposed sensor device, against cavity length ( ${L}_{\text {Cavity}}$ ) and misalignment effect between the cavity and high- ${k}$ dielectric, underneath the cavity of the sensor device. It is found that our proposed biosensor device works at its optimum with ${L}_{\text {Cavity}} =10$ nm, while the cavity is perfectly aligned with the underneath high- ${k}$ of the device. Furthermore, a comparison of our proposed device is performed against its equivalent high- ${k}$ only and SiO2 only TFET-based biosensors. For each aforementioned sensitivity parameter, it is found that our proposed DHGDM-TFET biosensor device outperforms the rest two devices, proving the superiority in sensing action.

Decoupling the Doppler Ambiguity Interval From the Maximum Operational Range and Range-Resolution in FMCW Radars

Classical saw-tooth Frequency Modulated Continuous Wave (FMCW) radars experience a coupling between the maximum unambiguous Doppler-velocity interval, maximum operational range, range-resolution and processing gain. Operationally, a trade-off is often necessarily made between these parameters. In this paper, we propose a waveform and a processing method that decouples the aforementioned parameter dependencies at the price of using multiple receiver channels within the radar. The proposed method exploits the fact that beat-frequency signals have the same baseband frequency, even if the transmitted and received chirps occupy different radio frequency bands, and have different center-frequencies. We concatenate those baseband signals in the time-frequency domain to restore the range-resolution and processing gain. An overview of FMCW parameters trade-off for related waveforms and a feasibility and limitations analysis of implementing the proposed processing method are presented. The method is verified by simulations and experiments with an FMCW radar for stable, moving and extended-moving targets. We additionally have highlighted its non-idealities in the simulations and experiments. We found that the proposed method indeed alleviates the trade-off between FMCW operational parameters and allows the extension of the Doppler ambiguity interval without compromising on those parameters.

Evaluating impacts of imprecise parameters on the performance of an ecosystem model OSMOSE-JZB

Ecosystem models are widely advocated for ecosystem-based fisheries management (EBFM). However, the use of ecosystem models is still limited in tactical fisheries management due to large uncertainties that undermine the confidence of stakeholders. Using a Monte Carlo simulation approach, this study quantified the impact of imprecise parameters on performance of a multi-species individual-based model “OSMOSE” (Object-oriented Simulator of Marine Ecosystems Exploitation) in evaluating the status of fish community, population, and individual. Uncertainties associated with the following five parameters were considered: fishing mortality (Mfishing), additional natural mortality (Mnatural), larval mortality (Mlarval), species-specific relative fecundity (RF), and the proportion of available low trophic level (LTL) biomass to high trophic level (HTL) groups (Plank.access). The imprecise value of Mlarval had the highest relative influence on model outputs. The imprecision of model outputs were sharply increased when the imprecisions of RF and Plank.access were high. The “compound sources” resulted in a greater imprecision of model predictions, confirming that the hierarchical model structure of OSMOSE facilitated the error diffusion. We also investigated the synergetic and antagonistic effects of aforementioned parameter uncertainty on the total biomass of the community (Biocom) and mean trophic level of the community (mTLcom). Both Biocom and mTLcom seemed not sensitive to the changes in Mnatural. The Mfishing and Mlarval had negative effects on mTLcom, and there was a positive relationship between two ecological indicators and last two parameters (RF and Plank.access). The Mlarval had a dominant impact on Biocom and mTLcom. Increasing Mfishing and Mlarval could result in a larger decline of Biocom and mTLcom compared to that caused by a single parameter. Similarly, there was a larger increase of Biocom and mTLcom after increasing RF and Plank.access. There was a small variation of Biocom and mTLcom when both Mfishing and RF changed, suggesting Mfishing could offset the effect of RF on Biocom and mTLcom. This study suggests that the imprecision of model parameters can greatly reduce utility of an ecosystem model. We recommend to develop research priority to reduce identified key sources of uncertainty and better understand error diffusion resulting from hierarchical model structures.

Morphological and Chemical Alterations of Root Surface after Er:YAG laser, Nd:YAG Laser Irradiation: A Scanning Electron Microscopic and Infrared Spectroscopy Study.

ABSTRACTAims and Objectives:This study aimed to evaluate the efficacy of Nd:YAG and Er:YAG lasers in removing the smear layer and to study the morphological and chemical alterations of the root surface using scanning electron microscopy (SEM) and infrared (IR) spectroscopy.Material and Methods:Fifty-five extracted upper incisor teeth were collected and 110 specimens of size 3 mm × 4 mm × 1 mm were prepared. For SEM evaluation, these samples were divided into six groups: A, B, and C. Group A comprised five samples that served as control. Groups B and C were further divided into five subgroups and each subgroup comprised five samples. All the specimens within the subgroups of B and C irradiated with 100, 200, 300, 400, and 500 mJ of Er:YAG laser and 211.66, 423.33, 635, 846.66, and 1058.33 J/cm2 of Nd:YAG laser, respectively. The morphological changes of the laser-treated sites were observed qualitatively using an arbitrary scale under SEM. The data obtained were statistically analyzed by one-way analysis of variance (ANOVA) multiple range test by Turkey’s honestly significant difference and Mann–Whitney U test. In chemical structural changes, Group D comprised five samples that served as nonirradiated control and Groups E and F were irradiated with the same aforementioned parameter and evaluated using Fourier-transform infrared spectroscopy.Results:Er:YAG laser at 100 mJ effectively removed smear layer without any crater formation. The Nd:YAG laser removed the smear layer at the energy density of 211.66 J/cm2 and 423.33J/cm2. The energy density of 1058.33 J/cm2 showed visible charring and deep crater with increased area of melted and resolidified minerals in SEM. In the chemical changes, IR spectroscopy graph showed the reduction in peak intensity beyond 846.66 J/cm2 of and new absorption band was noticed (2010cm–1 and 2017cm–1) at samples treated with 846.66 and 1058.33 J/cm2 of Nd:YAG laser.Conclusion:Er:YAG laser at lower energy density effectively removed smear layer without production of toxic substance as compared with Nd:YAG laser. Thus, Er:YAG laser can be used as an effective root biomodification agent.

Beltéri Wi-Fi jelerősség feltérképező mobil robot tervezése

A cikk egy autonóm Wi-Fi jelerősség feltérképező robot tervezését részletezi. Szó esik benne a Wi-Fi jelerősségének méréséről, a mérés során vizsgált paraméter tulajdonságairól és értelmezésének módjáról. A robot tervének részletezése előtt bemutatásra kerülnek a vele elvégzendő jelfeltérképezési folyamatok, a robot elvárt funkciói és azok megvalósítása. A cikk központi témájául szolgáló terv két nagyobb fejezetben van ismertetve. A publikáció első részében a robot fizikai felépítését alkotó fontosabb alkatrészek kerülnek bemutatásra, azok funkcióival, felhasználásuk okaival és módjával, valamint előnyeikkel és hátrányaikkal. A második részben pedig a robot működéséhez szükséges programok és azok alapjai kerülnek részletezésre.

Evaluation of the radiation shielding capabilities of the Na2B4O7–SiO2–MoO3-Dy2O3 glass quaternary using Geant4 simulation code and Phy-X/PSD database

The important gamma and neutron radiation shielding parameters of the Dy3+ doped (65-x)Na2B4O7–15SiO2–20MoO3-xDy2O3 (x = 0, 5, 10, 15, 20 mol%) glass quaternary system were investigated to provide decisive information for their application in radiation environment. Gamma and neutron attenuation properties of the glass systems studied here were evaluated in terms of the mass attenuation coefficient (μm), transmission fraction (TF), half value layer (HVL), mean free path (MFP), effective atomic number (Zeff), exposure buildup factors (EBF) and fast neutron removal cross-section (∑R) parameters. Investigation of the each aforementioned parameter was performed thanks to the utilization of Monte Carlo simulations along with the Phy-X/PSD database. The photon attenuation characteristics were evaluated for gamma ray energies varying between 0.284 and 5.0 MeV. This study indicated that increase of the Dy2O3 content from 0% to 20% mole, enhances the gamma shielding capability due to the increase of the parameters μm and Zeff. In this study it was also observed that ∑R increases from 0.099 to 0.107 cm−1 as the molar fraction of Dy2O3 increases.

Effects of the performance parameters of a wheelchair on the changes in the position of the centre of gravity of the human body in dynamic condition.

PurposeThe aim of this research is to establish whether, and to what extent, the tilt angle, gear ratio of the propulsion system and propulsion frequency of a wheelchair influence the position of the centre of gravity. Furthermore, it verifies the usefulness of such research using an original test stand.Materials and methodsThe article presents the effects of three operational parameters of a wheelchair on the position of the centre of gravity of the human body. The study included 27 wheelchair propulsion tests of a wheelchair with pushrim propulsion using the following variable parameters: gear ratio of the propulsion system, propulsion frequency and wheelchair tilt angle. The position of the centre of gravity of the human body was measured in dynamic conditions at 100 Hz. The results were represented with ellipses defining the region of variability of the position of the centre of gravity of the human body. The coordinates of the centre of gravity were measured in relation to the reference system, with the start point at the centre of the axis of rotation of the rear wheelchair wheels. The measurements were taken in a horizontal plane in relation to the base on which the test stand was positioned.ResultsThe research carried out shows that the inclination angle of the wheelchair has the greatest influence on position of the ellipse describing the position of the centre of gravity of the human body. By controlling the change in the inclination angle value in the range from 0° to 5.4°, the standard deviation of the length of the horizontal half-axis of the ellipse (SD a) equal to 31.2 mm was obtained. For comparison, by changing the frequency of pushes (40 to 50 pushes per minute) of the wheelchair at a constant inclination angle, the standard deviation of the horizontal half-axis length (SD a) equal to 8 mm was recorded. The results of the study show a change in the position of the centre of gravity of the human body in dynamic conditions. They are relative to the contact points of the wheelchair wheels with the ground. Using the dimensions of the plotted ellipses, one can determine the values of pressure that affect the wheelchair’s individual wheels. Conclusions–Increasing the value of each aforementioned parameter resulted in the increase of strength required by the operator to propel the wheelchair. It directly influenced the position of the centre of gravity during the test.