Polynomial Fitting Function Research Articles

A SINS/DVL navigation method based on hierarchical water velocity estimation*

Aiming at the problem that Doppler velocity log (DVL) cannot measure the velocity of the vehicle in the middle water environment, a Strap-down Inertial Navigation System (SINS)/DVL integrated navigation method based on hierarchical water velocity assistance is proposed. Firstly, according to the principle of DVL water layer flow measurement, the paper gives a hierarchical water recurrence principle. On this basis, a water velocity estimation method based on average weighted recurrence is proposed. The carrier depth information is introduced in this method, and the carrier velocity information is obtained by means of average value. This method can prevent the carrier velocity anomaly caused by the large error of single-layer water velocity measurement. Secondly, in view of the problem that the DVL water velocity measurement is easily disturbed in the middle water environment, a sliding window and a Chebyshev polynomial fitting function are introduced to realize the robust treatment of the water velocity. On this basis, combined with the Huber M robust filter algorithm, a hierarchical water velocity assisted integrated navigation algorithm based on the improved Huber M robust estimation is proposed to further improve the autonomous navigation accuracy in the middle water environment. Finally, the method proposed in this paper is verified by simulation. The results show that the hierarchical water velocity estimation method proposed in this paper can effectively estimate the water flow velocity, and its robust filtering algorithm can further improve the SINS/DVL integrated navigation accuracy in the middle water environment.

A new alternative for assessing ridging information of potato plants based on an improved benchmark structure from motion

Ridging based on crop height is essential for promoting potato plant growth and increasing potato yield. However, existing crop height estimation methods are greatly affected by the flatness of the digital terrain model (DTM), and estimation results with low leaf area are often unsatisfactory. To quickly and accurately estimate potato plant height in the early growing stage and guide ridge operation, an unmanned aerial vehicle (UAV) visible light system was used to collect RGB images of potato plants shortly after sowing and on the 50th day after planting. A red–green fit index (RGFI) was constructed using a digital orthophoto map (DOM) on the 50th day after planting potato plants and the Gaussian mixture model (GMM) threshold method to classify the experimental plots. The mean value of soil digital surface models (DSM) after classification was taken as DTM, and the benchmark structure from motion (BSfM) was proposed in combination with the structure from motion (SfM) method. The results showed that the BSfM had a higher correlation with the measured plant height than the SfM method, with an R2 value of 0.7807 and RMSE value of 1.8272 under second-order polynomial function fitting, indicating that BSfM could effectively minimise the effect of DTM flatness on plant height estimation. BSfM relies only on DSM distribution with soil and potato plants and can be easily calculated, with great potential as a rapid and cost-effective tool to estimate crop height.

Application of the Finite Difference Parabolic Equation Model in Forestry Remote Telemetry

In this article, the finite difference parabolic equation (FDPE) method is presented to calculate the propagation loss (PL) for electromagnetic waves (EWs) in the forest environment. The FDPE method is more efficient and convenient than the empirical models and has more advantages on compatibility and accuracy for long-range EWs prediction. The Debye–Cole dual dispersion model is used to simulate the effective permittivity of vegetation. The results of the FDPE model are compared with those of the advanced refractive effects prediction system and measurement results, and a good agreement is observed. Research found that PL for EWs varies with the effective permittivity. Also, the effective permittivity is a function of radio frequency, weight moisture content, and volume content of vegetation. Thus, it is necessary to establish a statistical model to determine some relations between the PL and plant biophysical parameters. The polynomial fitting method is adopted to process a large amount of PL data for obtaining a linear function. Then, the volume content and moisture content of vegetation can be determined according to the polynomial fitting function. It provides a novel and efficient method for forestry remote telemetry, which is specifically suitable for large-scale inaccessible region with serious environment.

Bi-fractional-order reference model parameters-based control system design

It is known that analytical manipulation of the time-domain representation of fractional order transfer function is, hitherto, a challenging task. In this study, a controller design methodology based on the direct synthesis design method is proposed using bi-fractional order transfer function as a reference model and certain time-domain criteria. First, an analysis examines the effects of bi-fractional order transfer function parameters, that is, commensurate fractional order, damping ratio and natural frequency, on the system time-domain criteria. This examination has allowed us to set up a relation between damping ratio and commensurate fractional order. Next, a polynomial function fitting is established in order to express the damping ratio in terms of this commensurate order. Bi-fractional-order reference model is regenerated using the above-mentioned relationship. Furthermore, a control design algorithm that utilizes the newly derived bi-fractional order reference model is developed by considering control signal limitations. The proposed fractional order control design method is then compared with globally optimized fractional order proportional-integral-derivative (PID) controllers under the same circumstances and performance index. Finally, the implementation of the proposed controller design algorithm is done on a real-time active suspension system. The results are very satisfactory and incoherent with the simulations.

Damage Distribution Map Based Damage Accumulation Calculation Approach for Welded Joints

Fatigue damage accumulation under variable amplitude loadings is vital for the life prediction of welded structures. An approach based on damage distribution mapping is presented. S-N curves of welded joints are utilized to construct fatigue damage zones, and a corresponding polynomial fitting function is derived from the heat transfer FEA solution. Experimental results for cruciform and T joints under tensile and three-point bending are employed for validation. Compared with four existing damage models, the proposed approach shows greater accuracy and provides a better description for the early stage of fatigue.

Extended model of bouncing boundary for droplet collisions considering numerous different liquids

Sprays are widely utilised in different technical and industrial applications. The produced droplet size spectrum is one of the most important parameters that determine the spray characteristics and performance. Depending on the operational conditions and the spray structure, the droplet size spectrum obtained after atomisation will be of course modified by collisions between droplets. In numerical calculations, the Euler/Lagrangian approach is a favourable method for obtaining relatively accurate predictions of spraying processes. However, for correctly modelling droplet collisions, reliable boundary line correlations are needed for distinguishing the different droplet collision outcomes, which are bouncing, coalescence, and separations. These boundary lines are summarised in so-called collision maps to demark the various outcome scenarios. The result of a binary droplet collision depends on numerous parameters, namely, the kinetic properties (droplet velocities, droplet diameter ratio, impact angle) and the physical properties of gas and droplets (droplet liquid, density and viscosity, surface tension, type of gas phase, gas phase pressure and temperature). The boundary line for bouncing, primarily used in numerical studies so far, was derived based on experiments with ethanol droplets by Estrade et al. (1999). However, this theoretical derivation, based on an energy balance, unfortunately neglects viscous dissipation effects. Therefore, the deviations of the predicted bouncing region are pretty large for liquids with higher viscosity or other physical properties. Hence, a data-driven model is proposed in this paper, with new assumptions and definitions, considering the dissipated energy during the collision and the shape changes (i.e., deformation) of the collision complex. For that purpose, two new parameters are introduced in the model, namely a shape factor and an energy conversion rate, both depending on the impact parameter B, which describes the lateral displacement of droplets at a collision. Therefore, the new bouncing model is related to the degree of droplet deformation. The dependence on B could be described by linear correlations with two parameters for slope and intercept. These parameters are correlated with the Ohnesorge number, and polynomial fitting functions were derived with the help of numerous available experiments for different liquids. The upper limit of Ohnesorge numbers in the present study was Oh<0.35. Due to the dependence on the Ohnesorge number, the proposed model very well captures the effect of liquid properties on the bouncing boundary, however, not necessarily the influences of environmental conditions and interface modifications. The model was validated by comparison with numerous available experimental results.

Tracking Nonradial Outflows in Extreme Ultraviolet and White Light Solar Images

Understanding the solar corona requires knowledge of its dynamics through its various layers and subsequent connectivity to the heliosphere. This requires understanding the nature of the outflows and the physical transitions through the middle corona (∼1.5–6.0 R s ). While this region is still inaccessible to in situ measurements, remote sensing observations are available, but their interpretation can be controversial due to line-of-sight effects and the nonradial motion of outflowing structures close to the Sun (≤3.0 R s ). In this work, we describe a method to mitigate these challenges by generating nonradial height–time profiles of outflows by using advanced image processing techniques. The northern and southern boundaries of a large equatorial streamer during the 2008 solar minimum were identified in STEREO/SECCHI solar images, using two different methodologies based on thresholds of brightness and piecewise polynomial function fitting. To address line-of-sight issues, we used tomographic reconstruction of the 3D distribution of the coronal electron density based on SECCHI/COR2 images. Spectral analysis of the time series of the position angle of the streamer boundary revealed its oscillatory nature at some heights at 36–48 and 10.5–14.6 hr. Dividing the distance between the northern and southern streamer boundaries in equal parts at each height, we obtained nonradial height–time paths from which we generated nonradial profiles of corona/solar wind plasma outflow. We tracked outflows as they moved uninterruptedly from the Sun in EUVI, through COR1 and into COR2. Finally, we discuss the preliminary results of nonradial plane-of-sky velocities for a coronal mass ejection and two small-scale features.

Infrared radiation denoising model of “sub-region-Gaussian kernel function” in the process of sandstone loading and fracture

Rock damage and fracture are the basic and common scientific problems that mostly happen during the extraction of minerals and construction engineering projects in a rock mass environment. These problems can cause dynamic coal mine catastrophes such as coal and gas explosions, rock bursts, and mine water inrush. The accurate and effective monitoring of these problems can provide reliable information for early warning of coal mine dynamic disasters, surrounding rock fractures process, and water inrush in mining face. Furthermore, these challenges can be effectively monitored using infrared radiation technology. However, the infrared radiation data can be affected in the presence of noises which can cause ineffective monitoring of the aforementioned problems. Therefore, it is essential to denoise the associated noises to enhance the infrared radiation characteristics effectively for the development of better monitoring and early warning system. This paper analyzed the characteristics of sandstone's infrared radiation noise curve under biaxial loading. The infrared radiation temperature curve's subregion denoising technique uses the correlation coefficient of a polynomial fitting function as an assessment index. As a result, the infrared radiation energy is suggested and presented as an infrared radiation index to establish the threshold of the Gaussian kernel function. A new model of “sub-region-Gaussian kernel function” average infrared radiation temperature denoising is established, which solves the problem of infrared radiation temperature distortion in the sandstone loading and fracture process. The findings of this research will lay down a theoretical and experimental foundation for the application of infrared monitoring technology to the effective monitoring and early warning of engineering projects such as coal mining, tunnel excavation and stability analysis of slope.

Numerical study of the Roberge-Weiss transition

We study the Roberge-Weiss phase transition numerically. The phase transition is associated with the discontinuities in the quark-number density at specific values of imaginary quark chemical potential. We parameterize the quark number density $\rho_q$ by the polynomial fit function to compute the canonical partition functions. We demonstrate that this approach provides a good framework for analyzing lattice QCD data at finite density and a high temperature. We show numerically that at high temperature, the Lee-Yang zeros lie on the negative real semi-axis provided that the high-quark-number contributions to the grand canonical partition function are taken into account. These Lee-Yang zeros have nonzero linear density, which signals the Roberge-Weiss phase transition. We demonstrate that this density agrees with the quark density discontinuity at the transition line.

FRUIT: A Blockchain-Based Efficient and Privacy-Preserving Quality-Aware Incentive Scheme

Incentive plays an important role in knowledge discovery, as it impels users to provide high-quality knowledge. To promise incentive schemes with transparency, blockchain technology has been widely used in incentive schemes. Currently, privacy, reliability, streamlined processing, and quality awareness are major challenges in designing blockchain-based incentive schemes. In this paper, we design a blockchain-based eFficient and pRivacy-preserving qUality-aware IncenTive scheme called FRUIT. With well-designed smart contracts, FRUIT achieves privacy, reliability, streamlined processing, and quality awareness during the whole procedure. Specifically, we design a novel lightweight encryption method by combining matrix decomposition with proxy re-encryption and a privacy-preserving task allocation based on the polynomial fitting function and hash function. Then, we leverage our proposed lightweight encryption and task allocation to build an efficient and privacy-preserving knowledge discovery protocol in order to securely calculate the data quality and truthful knowledge. To promise user reliability in the incentive scheme, we utilize the Dirichlet distribution to realize the automatic reputation prediction based on the data quality by deploying the reputation management on the blockchain. Moreover, we also deploy the payment management on the blockchain, endowing the incentive scheme to reward participants based on the data quality automatically. Through a detailed security analysis, we demonstrate that data privacy and task privacy are well preserved during the whole process. Theoretical analysis and extensive experiments on real-world datasets demonstrate that FRUIT has acceptable efficiency and affordable performance in terms of computation cost, communication overhead, and gas consumption.

MXene (Ti3C2Tx) coated highly-sensitive D-shaped photonic crystal fiber based SPR-biosensor

In this paper, a D-shaped surface plasmon resonance (SPR) refractive index (RI) based biosensor is reported for the earlier detection of various bio-analytes. The lattice of D-shaped photonic crystal fiber (PCF) offers a modified rhombus pattern for cladding air holes. D-shaped PCF is an open channel structure that fundamentally provides ease while interacting with different bio-analytes as compared to closed channels SPRs. A nanoscale MXene (Ti3C2Tx) layer is introduced with a uniform coating that drastically enhances the sensor’s sensitivity and performance. Finite element method (FEM) is employed to determine dispersion characteristics to acquire the confinement loss spectra as a function of wavelength for various bio-analytes. SPR shifts the resonant interference dip when RI of bio-analytes changes. The proposed SPR sensor with Au/ Ti3C2Tx layer exhibits maximum RI sensitivity of 47,260 nm/RIU at an analyte refractive index of 1.42 with a detection resolution of 2.11 × 10−6 RIU, which is 1.7 times higher than that of a single Au-layer SPR sensor. Moreover, it detects a wider range of bio-analytes (i.e., 1.30–1.43) using a third-order polynomial fitting function corresponding to the wavelength shift. It covers the detection of most known bio-analytes, i.e., cancerous cervical, breast and blood cells, adrenal gland, glucose concentration, proteins, viruses or DNA/RNA, etc.

Coupling effect of pyrolysis temperature and condensing temperature on the enrichment of high value-added phenolic compounds in bio-oil from pyrolysis of crop straw

Pyrolysis experiments were performed using cotton straw and corn straw as raw materials at 723 and 773 K. The variations in condensation efficiency, moisture, and content of important components in bio-oil condensed from pyrolysis vapors were investigated in a water-bath condensation temperature of 313–363 K. The condensing efficiency, moisture, and content of important components of bio-oil increased with increased pyrolysis temperature. The single pyrolysis temperature provided limited control over the quality of bio-oil. The variation in condensing temperature affected the condensing of pyrolysis vapors. As the condensing temperature increased, the moisture in bio-oil was reduced by 200%, and the maximum content of the important components was elevated. The phenol content of the target bio-oil increased by 340.40%. For guaiacol and its derivatives, the relationship between condensing temperature and their content was analyzed using a polynomial fitting function to explore the phase-transition patterns.

Investigating the impact of growth time of CdSe quantum dots on the structure and optical properties of its nanocomposites with SiO2 for improvement of optical devices

This study effectively succeeded in synthesizing CdSe QDs and CdSe- SiO2 nanocomposites with controllable tunable size and spectacular morphology by using a solvothermal technique. UV–visible spectroscopy was used to study the effect of the growth time of CdSe QDs on the optical properties of its nanocomposite with SiO2. The structure of the prepared nanocomposites of CdSe- SiO2 was studied through the measurements of X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy FTIR. The Effective Mass Approximation model (EMA), Simple Exponential Function (SEF), and Polynomial Fitting Functions (PFF) were employed to compute nanoparticle sizes, providing particle sizes of 3.86, 4.19, and 3.72 nm, respectively, for CdSe- SiO2 nanocomposites (2 min). For the same nanocomposite, these theoretical values were comparable to the experimental values of the particle sizes deduced from measurements of TEM (4.5 nm) and XRD (3.4 nm). The deduced optical parameters of CdSe-SiO2 nanocomposite, such as refractive index, dielectric constant, optical conductivity, electrical susceptibility, and some others, relied on the growth time of CdSe QDs. The absorption peaks of CdSe -SiO2 nanocomposites suffered from a bathochromic shift which increases as the growth time of CdSe QDs increases. Increasing the growth time of CdSe QDs resulted in increasing the reflection loss factor and decreasing the optical electronegativity. The values of the volume energy loss function (VELF) are greater than the values of the surface energy loss function (SELF) for the different nanocomposites. Consequently, the fast electrons miss their energies through their propagation within the studied materials more than through traveling on their surfaces. The enhancement of n values of nanocomposites of CdSe-SiO2 by increasing the growth time can candidate them to be usefully applied as antireflection coating for solar cells.

Coupling Interference between Eddy Current Sensors for the Radial Displacement Measurement of a Cylindrical Target.

In the radial displacement measurement of a small-sized cylindrical target, coupling interference between eddy current sensors reduces the accuracy of the measurement. In this study, finite element method (FEM) simulation based on ANSYS Maxwell was adopted to investigate the relationships between the coupling coefficient of the sensors and different parameters including the lift-off, cylinder diameter, axis angle, material, and excitation frequency. The experimental results were consistent with the simulation results. The coupling interference between the sensors increased with the decrease in the lift-off and cylinder diameter. The coupling effect decreased significantly when the probe axis angle increased to 120°, and the decrease in the sensor sensitivity was acceptable. A polynomial fitting function fitted the output signal well. A compensation method was given based on the compensation necessity evaluation. The results showed that the error of the rotor motion track was significantly decreased after compensation.

Liquid-cooled structure design and heat dissipation characteristics analysis of cross-flow channels for lithium batteries

A detailed three-dimensional thermal model is developed to examine the thermal behaviour of a lithium-ion battery. This model is a cross-flow liquid cooling model, which can make the heat dissipation of lithium-ion battery pack achieve higher safety. Two kinds of fluids are used for cooling, and the polynomial fitting function is used as the heat source term of lithium battery pack. The battery temperature distribution under the conditions of different Reynolds numbers, different numbers of micro-channel and different micro-channel radii are studied for this model. The simulation results show that the maximum battery temperature is 295.84 K, the minimum battery temperature is 293.14 K, and the maximum temperature difference of the battery pack is 2.7 K. The maximum temperature and temperature difference of the battery under the model are in line with the reasonable operating temperature range of lithium-ion battery pack. The maximum temperature of battery pack decreases with the increase of Reynolds number, but the effect of Reynolds number on heat dissipation of lithium-ion battery pack has a critical value. As the number of micro-channels increases, the maximum temperature of the battery string decreases. However, when the number of micro-channels increases to a certain value, the maximum temperature of the battery pack decreases slowly. The maximum temperature of the battery pack does not decrease monotonically as the radius of the micro-channel increases. Orthogonal analysis results show that the Reynolds number has the greatest influence on the cooling effect of the model, followed by the size of the micro-channel radius, and the number of micro-channels has the least influence. The optimized liquid cooling model can effectively reduce the maximum temperature of lithium-ion battery in theory, and the maximum temperature of lithium-ion battery decreases by 26.24 K in comparison with that of single battery at 2C discharge rate. The reliability of the cross-flow channel model is proved by numerical analysis, and it is also proved that the cross-flow channel has an equilibrium point between the perturbation gain and the flow retarding effect. The heat dissipation effect of lithium- ion battery pack is correlated with the number and radius of micro-channels, but not a single positive correlation. Reasonably increasing the number and size of micro-channels can effectively enhance the heat dissipation effect of battery pack.

INSAT-3D and -3DR relative radiometric performance over bright target

The Geostationary Earth Orbit (GEO) satellite INSAT-3D and -3DR derived data products plays a vital role in helping to develop long-term trends of many climate variables and to improve our understanding of earth's environmental processes and dynamics occurring on the land, in the oceans and in the atmosphere. In order to provide high quality, consistent and well calibrated measurements, the radiometric calibration of the sensor must be consistent, stable and traceable to its calibration standards. Due to absence of an onboard calibration mechanism for the visible (VIS) and Short Wave Infra-Red (SWIR) bands, accuracy of Top-of-atmospheric radiance of these bands data depend on vicarious calibration methods to provide post launch calibration coefficients to compensate for the degradation responsivity. In this study, a methodology has been implemented to perform degradation assessment and seasonal variation pattern for the visible and SWIR band of INSAT-3D and -3DR satellite based on clear-sky observations. The current methodology relies on clear sky apparent reflectance which are derived from level-1 images over pseudo-invariant desert target. In this study, authors are focused to investigate visible and SWIR band performance based on clear-sky observations over desert target and the instrument long-term drift traced by a polynomial fitting function. A trending algorithm is proposed here, which consists of a polynomial function (for the description of instrument degradation performance) with two sine terms for quashing the impact of the seasonal variations of the solar zenith angle and atmospheric constituents, is applied to fit the time series of apparent reflectance.

The effect of graphene on structure and optical properties of CdSe nanoparticles for optoelectronic application

CdSe-reduced Graphene Oxide (CdSe-rGO) nanocomposite was synthesized using a facile hot injection method with excellent control over the size and morphology. The superb distribution of the CdSe quantum dots (CdSe QDs) and the tightly anchoring to the graphene sheets enhance their optical properties. Therefore, the effect of reduced Graphene oxide (rGO) on the structure and optical properties of CdSe nanoparticles is studied by X-ray diffraction (XRD), UV–visible spectroscopy, and transmission electron microscopy (TEM). As well as Effective mass approximation model (EMA) and Polynomial Fitting Functions (PFF) were used to calculate the sizes of nanoparticles, yielding particle sizes ranging from 4.64 to 5.46 nm and 2.74–3.72 nm, respectively. These values were comparable to those obtained by TEM and XRD. Furthermore, the data revealed that the direct energy gap of the CdSe QDs was reduced from 2.33 eV for the smallest size to 2.17 eV for the largest size. The optical parameters of CdSe-rGO nanocomposite such as the refractive index and extinction coefficient were increased with the particle size growth. As well, optical dielectric constant and optical conductivity were improved due to the increase of the particle size of CdSe QDs in the CdSe-rGO nanocomposite. So, the capability of CdSe-rGO nanocomposite to tune the optical parameters makes it a suitable candidate for a wide range of applications, specifically optoelectronics.

Monitor unit prediction model for wobbling proton therapy with ridge filters.

We introduced an output factor (cGy/MU) prediction model for wobbling proton beams over the full range of proton energy, scatterer thickness, and the width of spread-out Bragg peak (SOBP). From December 2015 to August 2020, 1990 wobbling proton fields were used to treat patients, where 1714 fields had a diameter smaller than 11cm and 276 had a diameter between 11 and 16cm, which were designated as small and middle wobbling radius cases, respectively. The output factor is defined as the ratio of proton absorbed dose at mid-depth of SOBP to monitor unit (MU). It depends dominantly on proton energy, scatterer thickness, and the width of SOBP. We established the prediction model using the polynomial fitting function and determined its coefficients for the small and middle wobbling radius cases. We evaluated the accuracy of our prediction model by calculating the difference between predicted and measured output factors. For the small wobbling radius cases, the mean value of the output factor difference was 0.22% with a standard deviation of 1.3%. For the middle wobbling radius cases, the mean value was 0.20% and with a standard deviation of 0.79%. The large deviation was especially observed for wobbling proton beams having small field size and small width of SOBP. We made a prediction model of output factor for wobbling proton beams, thereby determining MU of each beam. This included the dependency of the output factor on the proton energy between 70 and 230 MeV, scatterer thickness, and the width of SOBP. For 93.6% of the small and 95.5% of the middle wobbling radius cases, the deviation between predicted and measured output factor was below 3%. The cases with deviations of predicted and measured output factor above 3% had small field size and small width of SOBP. The accuracy of our prediction model would be improved by adopting the field size effect and measuring more cases of small field size and small SOBP width in the future.

A Comparative Study of Fatigue Energy Dissipation of Additive Manufactured and Cast AlSi10Mg Alloy

In this paper, the fatigue energy dissipation of Gravity Casting (GC) and Laser-based Powder Bed Fusion (LPBF) AlSi10Mg alloys under cyclic loading are investigated. The increase in surface temperature related to the energy dissipation effect is decoupled and used to predict the fatigue limits of GC and LPBF AlSi10Mg alloys as being 55.8% UTS and 33.9% UTS, respectively. The energy dissipation rate is obtained by solving the one-dimensional thermal diffusion problem. This energy dissipation is separated into related and unrelated fatigue damage using polynomial function fitting. The energy dissipation related to fatigue damage for LPBF specimens is observed to be higher than that of GC specimens, which indicates worse fatigue performance. The fatigue damage entropy is employed to predict the fatigue life of both GC and LPBF AlSi10Mg alloys, which has a good agreement with the results of a traditional fatigue experiment.

Calibration of Gafchromic XR-RV3 film under interventional radiology conditions

Abstract Introduction: The purpose of the study was the calibration of Gafchromic films in clinical interventional radiology conditions and the assessment of the influence of dose range, the shape of the fitting curve, and its practical application. The aim of the work was to show how practically perform calibration in a wide range of doses. Material and methods: Gafchromic XR–RV3 films were included in the study. The calibration was performed for A and B film series separately. Doses from the range of 0 – 8 Gy were used. Film dosimeters were read out in reflective mode with a commercial flatbed scanner. Results: Among various degrees of a polynomial function, the best fit, which fulfilled the chosen criterion of 95% agreement between measured and reconstructed doses and simple equation criterion, was observed for third-degree polynomial. The fitting curve where the dose is the function of optical density (logMPV) was demonstrated to be more precise than the fitting curve based on MPV only. To minimize the difference between dose absorbed by the film and dose reconstructed from the fitting curve below 5% it is necessary to divide the calibration range of 0 – 8 Gy into two subranges for use in interventional radiology. This difference was set at a maximum level of 3.8% and 1.9% for the lowand high-dose range, respectively. Each series of films may have a slightly different calibration curve, especially for the low dose range. A deviation of up to 36% between two batches of Gafchromic film was observed. Conclusions: For the third-degree polynomial fitting function (one of the recommended in the literature) calibration should be done into low and high dose ranges and for each batch separately. A systematic error higher than 20% could be introduced when the fitting curve from one film batch is applied to the other film batch.