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Wyniki wyszukiwania dla: RADIO CHANNEL MODELLING
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Simulation of the switched reluctance drive system
PublikacjaSwitched reluctance motors (SRM), unlike other types of motors, for their application require a control system and the supply from a power electronic converter. A method of modelling and mathematical model of an SRM in a switched reluctance drive (SRD) system is presented in the paper. Modelling is based on Lagrange's energy method. Coefficients of the Lagrange's equation have been calculated using the finite element method (FEM)....
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Uwarunkowania teleinformatyczne technologii radia programowalnego. .
PublikacjaOmówiono zagadnienie realizacji infrastruktury teleinformatycznej dla sieci radiokomunikacyjnej pracującej przy użyciu technologii radia programowalnego(software radio). Przedstawiono koncepcję tworzenia takiej technologii, która w przyszłości zdominuje rynek usług telekomunikacyjnych. Poruszono problem kosztów budowy i wdrożenia, co ostatecznie zadecyduje o sukcesie rynkowym tego przedsięwzięcia.
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Polynomial Chaos Expansion in Bio- and Structural Mechanics
PublikacjaThis thesis presents a probabilistic approach to modelling the mechanics of materials and structures where the modelled performance is influenced by uncertainty in the input parameters. The work is interdisciplinary and the methods described are applied to medical and civil engineering problems. The motivation for this work was the necessity of mechanics-based approaches in the modelling and simulation of implants used in the repair...
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Polynomial Chaos Expansion in Bio-and Structural Mechanics
PublikacjaThis monograph presents a probabilistic approach to modelling the mechanics of materials and structures where the modelled performance is influenced by uncertainty in the input parameters. The work is interdisciplinary and the methods described are applied to medical and civil engineering problems. The motivation for this work was the necessity of mechanics-based approaches in the modelling and simulation of implants used in the...
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The Backbone Coloring Problem for Small Graphs
PublikacjaIn this paper we investigate the values of the backbone chromatic number, derived from a mathematical model for the problem of minimization of bandwidth in radio networks, for small connected graphs and connected backbones (up to 7 vertices). We study the relationship of this parameter with the structure of the graph and compare the results with the solutions obtained using the classical graph coloring algorithms (LF, IS), modified...
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Digital Audio Broadcasting or Webcasting: A Network Quality Perspective
PublikacjaIn recent years, many alternative technologies of delivering audio content have emerged, with different advantages and disadvantages. In this paper pros and cons of digital audio broadcasting and webcasting transmission techniques in a network quality perspective are described. A case study of user expectations with respect to currently available services is analyzed, and the perceived quality of real digital broadcasted and webcasted...
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Time-domine Dipole Fields in acoustic and Elektromagnetics
PublikacjaThe ultrawideband (UWB) radio technique presents a challenge not just for technology. The UWB carrier-free pulses act at a close distance, their electromagnetic fields being very different from classic monochromatic plane wave. The author proposes to adapt a time-domian approach to analysis of broadband spherical fields, both acoustic and electromagnetic, in fundamental cases of quasi-point physical sources.
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Effect of Soft Handover on the Capacity of WCMDA/FDD Interfece Using MRC RAKE Receiver in Uplink
PublikacjaIn the paper the mechanism of soft and hard hanover in UMTS is presented. Simulation tests for different services having various performance requirements and transmission rates have beeen made. Simulation results showing effect of soft handover in comparison with hard handover on the capacity of WCMDA/FDD radio interfaceare described, when the RAKE receiver with Maximal Ratio Combining has been implemented in RNC.
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Detection of the Direct Sequence Spread Spectrum Signals with BPSK Modulation
PublikacjaThis paper presents a method of the DS CDMA signals with BPSK modulation detection through the examination of the enhanced signal spectrum density. On the base of experiments carried out on the real radio communication signals the impact of a narrowband emission occurring in the examined frequency band on the detection process effectiveness was shown. The results of the experiment aimed at the detection of the satellite navigation...
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M2M communications system proposal for maritime applications
PublikacjaThis article describes the proposal to use the M2M communication to enhance the safety of people, ships and other marine infrastructure, in broadly defined marine systems. In addition, there are numerous examples of planned solutions to be implemented in the near future as well as new services. The proposal for M2M communication system architecture is described below. In addition, the use of the STRUGA system radio interface as...
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Novel Fault Identification for Electromechanical Systems via Spectral Technique and Electrical Data Processing
PublikacjaIt is proposed, developed, investigated, and validated by experiments and modelling for the first time in worldwide terms new data processing technologies, higher order spectral multiple correlation technologies for fault identification for electromechanical systems via electrical data processing. Investigation of the higher order spectral triple correlation technology via modelling has shown that the proposed data processing technology...
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On the influence of the acceleration recording time on the calculation of impact severity indexes
PublikacjaThe paper concerns with the analysis of normative requirements pertaining to experimental setup of a crash test and its numerical modelling. An overview of parameters describing the collision of a vehicle with a road restraining system is presented. A short description of a concrete road safety barrier is presented. A brief description of numerical modelling procedures for crash tests is given as well. The parametric influence...
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On Applications of Fractional Derivatives in Circuit Theory
PublikacjaIn this paper, concepts of fractional-order (FO) derivatives are discussed from the point of view of applications in the circuit theory. The properties of FO derivatives required for the circuit-level modelling are formulated. Potential problems related to the generalization of transmission line equations with the use of FO derivatives are presented. It is demonstrated that some of formulations of the FO derivatives have limited...
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Hydraulic resistance analyses of selected elements of the prototype Stirling engine
PublikacjaThe paper presents the results of simulation tests of hydraulic resistance and temperature distribution of the prototype Stirling alpha engine supplied with waste heat. The following elements were analyzed: heater, regenerator and cooler. The engine uses compressed air as a working gas. Analyses were carried out for three working pressure values and different engine speeds. The work was carried out in order to optimize the configuration...
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Testing OFDM Transmission Schemes for Shallow Water Acoustic Communications
PublikacjaLarge variability of communication properties of underwater acoustic channels, and especially strongly varying instantaneous conditions in shallow waters, is a tough challenge for the designers of underwater acoustics communication (UAC system. There is a need for developing adaptive signaling schemes that would dynamically optimize signal parameters in both physical and link layers of communication protocols. The orthogonal frequency...
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System eLoran w Europie
PublikacjaW artykule przedstawiono historię powstania oraz stan aktualny systemu eLoran w Europie. Opisano także strukturę sygnałów Loran-C i sposób transmisji danych w rozwiązaniach Eurofix i Loran Data Channel, a także plany rozwojowe systemu w różnych częściach świata.
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A Nyquist filter of fractional delay
PublikacjaIn the paper a novel discrete-time FIR fractonal delay specjal filter is investigated. This is a Nyquist filter which, besides the traditional its attribute (interymbol interference (ISI) free property), has the ability to compensate for subsample transmission delay involved, for example, in multipath propagation channel. The performance of the filter is analysed and illustrated.
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Synchronic digital stereophotography and photogrammetric analyses in monitoring the flow of liquids in open channels
PublikacjaThe authors present the results of their research into photogrammetric documents based on synchronic digital images. Examples presented in the paper indicate the value of synchronic stereophotography in registering phenomena connected with liquids. Combining synchronic stereophotography with photogrammetric methods has allowed the authors to develop an application useful for monitoring the flow of a liquid in an open channel.
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Diagnostics of thermal processes in antenna systems of broadcast stations
PublikacjaDiagnostics is an important element associated with the operation of a radio antenna systems, allowing earlier detection of potential damage. Thermography is one of the diagnostic tools, which allows for non-invasive assessment of technical condition. It brings together both financial savings associated with the removal of the damage and the potential effects caused by it. The article presents an example of using a thermal imaging...
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Narrowband Transmission Quality in Presence of Modified IEEE 802.15.4a UWB Signal
PublikacjaThis paper presents results of measurement of narrowband transmission quality in presence of impulse radio UWB interference. In the first part of paper, unmodified IEEE 802.15.4a IR UWB signal is used. Then some modification of transmitted pulse sequence is proposed, which allow to reduce UWB power spectral density at frequency of narrowbandtransmission. Finally narrowband transmission quality in presence of modified ultrawideband...
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Development of models for nitrogen-removal processes in subsurface flow constructed wetlands
PublikacjaThis paper summarizes recent progress in modelling approach of subsurface flow constructed wetlands (SSF CWs), focusing on nitrogen removal processes.
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Thermal self-action effects of acoustic beam in a vibrationally relaxing gas
PublikacjaThermal self-action of acoustic beam in a molecular gas with excited internal degrees of molecules’ freedom, is studied. This kind of thermal self-action differs from that in a Newtonian fluid. Heating or cooling of a medium takes place due to transfer of internal vibrational energy. Equilibrium and non-equilibrium gases, which may be acoustically active, are considered. A beam in an acoustically active gas is self-focusing unlike...
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Modeling the impact of discretizing rotor angular position on computation of field-oriented current components in high speed electric drives
PublikacjaModern drives consist of alternating current electric motors, and the field-oriented control (FOC) of such motors enables fast, precise, and robust regulation of a drive's mechanical variables such as torque, speed, and position. The control algorithm, implemented in a microprocessor, requires feedback from motor currents, and the quality of this feedback is essential to a drive's control properties. Motor phase currents are sampled...
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Solving Boundary Value Problems for Second Order Singularly Perturbed Delay Differential Equations by ε-Approximate Fixed-Point Method
PublikacjaIn this paper, the boundary value problem for second order singularly perturbed delay differential equation is reduced to a fixed-point problem v = Av with a properly chosen (generally nonlinear) operator A. The unknown fixed-point v is approximated by cubic spline vh defined by its values vi = vh(ti) at grid points ti, i = 0, 1, ... ,N. The necessary for construction the cubic spline and missing the first derivatives at the boundary...
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Analysis of Interspike-Intervals for the General Class of Integrate-and-Fire Models with Periodic Drive
PublikacjaWe study one-dimensional integrate-and-fire models of the general type x˙=F (t, x) and analyze properties of the firing map which iterations recover consecutive spike timings. We impose very week constraints for the regularity of the function F (t, x), e.g. often it suffices to assume that F is continuous. If additionally F is periodic in t, using mathematical study of the displacement sequence of an orientation preserving circle...
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Nuclear Power Plant Steam Turbine - Modeling for Model Based Control Purposes
PublikacjaThe nature of the processes taking place in a nuclear power plant (NPP) steam turbine is the reason why their modeling is very difficult, especially when the model is intended to be used for on-line optimal model based process control over a wide range of operating conditions, caused by changing electrical power demand e.g. when combined heat and power mode of work is utilized. The paper presents three nonlinear models of NPP steam...
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On the theory and numerical simulation of acoustic and heat modes interaction in a liquid with bubbles: acoustic quasi-solitons
PublikacjaTeoria rzutowania zaburzenia ogólnego na mody. Zastosowanie metody do badań układu równań typu Korteweg`a-de Vries`a. Rozwiązania analityczne i simulacje numeryczne.
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Extensions of Quasilinearization Method for Differential Equations with Integral Boundary Conditions
PublikacjaPraca dotyczy równań różniczkowych z warunkami brzegowymi typu całkowego. Podano warunki dostateczne na istnienie jedynego rozwiązania takiego zagadnienia i pokazano, że odpowiednio konstruowane ciągi monotoniczne są zbieżne do tego rozwiązania i jest to zbieżność kwadratowa. Te monotoniczne ciągi są przybliżonymi rozwiązaniami problemu wyjściowego i obustronnie szacują szukane rozwiązanie.
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Electro-mechanical shear buckling of piezoelectric nanoplate using modified couple stress theory based on simplified first order shear deformation theory
PublikacjaThis paper studies the electro-mechanical shear buckling analysis of piezoelectric nanoplate using modified couple stress theory with various boundary conditions.In order to be taken electric effects into account, an external electric voltage is applied on the piezoelectric nanoplate. The simplified first order shear deformation theory (S-FSDT) has been employed and the governing differential equations have been obtained using...
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Study of free convective boundary layer of isothermal lateral surface of axisymmetrical horizontal body
PublikacjaPrzedstawiono rozwiązanie równań Naviera-Stokesa i Fouriera-Kirchhoffa we współrzędnych tau i sigma. Pierwsza jest styczną a druga normalną do konwekcyjnych linii prądu, wzdłuż jakich porusza się ogrzany od powierzchni płyn. Wynik w postaci równania na grubość warstwy przyściennej zweryfikowano dla granicznych przypadków ciała obrotowego o poziomej osi symetrii (stożka poziomego i kołowej pionowej płyty).
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Protection System Design of Induction Motor for Industries
PublikacjaThe fundamental and durable structures of induction motor, as well as their low manufacturing cost, make them popular components in a wide range of current applications. Providing a safety net for employees is a must-have for businesses. This project’s motivation for improvement is to provide industrial motors, lift motors, pumps, and so on with safety. An induction motor’s primary goal is to protect it from problems, such as...
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A PAIR OF PERFECTLY CONDUCTING DISKS IN AN EXTERNAL FIELD
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A fast algorithm for computing the flux around non-overlapping disks on the plane
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Expedited constrained multi-objective aerodynamic shape optimization by means of physics-based surrogates
PublikacjaIn the paper, computationally efficient constrained multi-objective design optimization of transonic airfoil profiles is considered. Our methodology focuses on fixed-lift design aimed at finding the best possible trade-offs between the two objectives: minimization of the drag coefficient and maximization of the pitching moment. The algorithm presented here exploits the surrogate-based optimization principle, variable-fidelity computational...
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Problem of proper decomposition and initialization of acoustic and entropy modes in a gas affected by the mass force
PublikacjaThe relations connecting perturbations specific for acoustic and entropy modes in an accelerated fluid or in a fluid affected by constant mass force, are derived. They allow to decompose the total vector of perturbations and the overall energy into acoustic and non-acoustic parts uniquely at any instant. In order to do this, three quantities are required, for example total perturbations in entropy, pressure and velocity. The evaluations...
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Torsional buckling and post-buckling of columns made of aluminium alloy
PublikacjaThe paper concerns torsional buckling and the initial post-buckling of axially compressed thin-walled aluminium alloy columns with bisymmetrical cross-section. It is assumed that the column material behaviour is described by the Ramberg–Osgood constitutive equation in non-linear elastic range. The stationary total energy principle is used to derive the governing non-linear differential equation. An approximate solution of the equation...
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Dynamic analysis of lightweight structure of the Viaduct Millau in France subjected to the wind fluctuations described by Karman’s and Davenport’s spectrum
PublikacjaThe article presents numerical simulations for wind impact modelling on the Millau Viaduct structure in France performed with two independent spectrum generation methods. The viaduct's construction in affected by strong forces, as it is situated in the Tarn river's valley. Thus, the loading coming from the wind cannot be modelled, the way it is in case of simple structures as static loading, but as a loading in a form of a spectrum...
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Quality Aspects in Digital Broadcasting and Webcasting Systems: Bitrate versus Loudness
PublikacjaIn this paper the quality aspects of bitrate and loudness in digital broadcasting and webcasting systems are examined. The authors discuss a survey concerning user preferences related with processing and managing audio content. The coding efficiency of a popular audio format is analyzed in the context of storing media. An objective study on a representative group of signal samples, as well as a subjective study of the perceived...
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Statistical Tuning of Walfisch-Ikegami Model for the Untypical Environment
PublikacjaThe Walfisch-Ikegami model has been investigated in terms of mobile radio systems designing in the untypical environment such as the maritime container terminal. The measurement equipment and procedures have been described as well as characteristics of investigated environment. Results of the statistical tuning in terms of path loss estimation in such environment have been analysed. The analysis has proved improvement of the path...
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Statistical Tuning of Walfisch-Ikegami Model for the Untypical Environment
PublikacjaThe Walfisch-Ikegami model has been investigated in terms of mobile radio systems designing in the untypical environment such as the maritime container terminal. The measurement equipment and procedures have been described as well as characteristics of investigated environment. Results of the statistical tuning in terms of path loss estimation in such environment have been analysed. The analysis has proved improvement of the path...
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Selected Propagation Models Modification for Application in Container Terminal
PublikacjaIt is particularly important to look for any propagation model that could be useful for designing mobile radio systems in container terminal environment. The selected propagation models have been investigated. The applied research methodology has been described too. Results of the statistical adjustment in terms of signal loss determination in such environment have been analysed. The analysis have proved effectiveness of adjustment...
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Empirical Adjustment of the Selected Propagation Models for Application in the Peculiar Environment of the Container Terminal
PublikacjaIt is important to look for any propagation model that could be useful for designing mobile radio systems in container terminal environment. Selected propagation models have been investigated. The applied research methodology has been described too. Results of the statistical adjustment in terms of signal loss determination in such environment have been analysed. The analysis has proved effectiveness of adjustment by increasing...
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Narrowband Transmission Quality in Presence of Modified IEEE 802.15.4a UWB Signal
PublikacjaThis paper presents results of measurement of narrowband transmission quality in presence of impulse radio UWB interference. In the first part of paper, unmodified IEEE 802.15.4a IR UWB signal is used. Then some modification of transmitted pulse sequence is proposed, which allow to reduce UWB power spectral density at frequency of narrowband transmission. Finally narrowband transmission quality in presence of modified ultrawideband...
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Damaged plasticity model - seismic analysis of structure of the Petronas Twin Towers (Kuala Lumpur) in Malaysia
PublikacjaThe article presents numerical simulations for the modelling of seismic impact on the structure of Petronas Twin Towers (Kuala Lumpur) in Malaysia with application of two methods. The Response Spectrum method, in which a spectrum of the structure's responses to an earthquake's impact is generated and the Acceletogram (BETA) method, in which we generate dynamic load in the form of a diagram of the connection between acceleration...
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Variable Order Differential Models of Bone Remodelling * *This work was supported by FCT, through IDMEC, under LAETA, projects UID/EMS/50022/2013, BoneSys, joint Polish-Portuguese project Modelling and controlling cancer evolution using fractional calculus, PERSEIDS (PTDC/EMS-SIS/0642/2014) and IF/00653/2012
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Shallow-Water Acoustic Communications in Strong Multipath Propagation Conditions
PublikacjaA phenomenon that has a strong impact on signal transmission conditions in Underwater Acoustic Communication (UAC) systems is multipath propagation. As a result of multipath propagation, the transmitted signal undergoes time dispersion which results in inter-symbol interference observed on the receiving side. Time dispersion is large, especially in horizontal channels in shallow waters which significantly limits the transmission...
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Hybrid System for a Person Tracking in Harsh Indoor Environments
PublikacjaIn the article, the prototype of a system for a person tracking in a harsh indoor environment, especially when no other commercially available radiolocalization system can be used, was briefly described. The prototype realizes the data fusion, i.e. combines data from inertial and environmental sensors and radio distance measurements to estimate the position of a moving person. It is worth noting that the concept and practical realization...
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Demonstrator technologii C-IED
PublikacjaArtykuł przedstawia budowę i działanie opracowanego na Politechnice Gdańskiej demonstratora technologicznego systemu AEGIS, przeznaczonego do przeciwdziałania atakom z wykorzystaniem prowizorycznych urządzeń wybuchowych detonowanych drogą radiową (RCIED — Radio Controlled Improvised Explosive Devices). Przedstawiono zaimplementowaną oryginalną metodę generowania sygnału zagłuszającego o dowolnie ukształtowanym widmie częstotliwościowym,...
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Research of Accuracy of RSSI Fingerprint-Based Indoor Positioning BLE System
PublikacjaRadio localization in indoor environment is still a challenging task due to environment volatility. In the paper are compared achieved localization accuracies for RSSI-Fingerprinting method utilizing Bluetooth Low Energy (BLE) for two different environments: large empty hall and narrow corridor. Measurements were done by 6 different smartphones of 3 different producers, which makes those measurements unique as accuracies achieved...
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Research of Accuracy of RSSI Fingerprint-Based Indoor Positioning BLE System
PublikacjaRadio localization in indoor environment is still a challenging task due to environment volatility. In the paper are compared achieved localization accuracies for RSSI-Fingerprinting method utilizing Bluetooth Low Energy (BLE) for two different environments: large empty hall and narrow corridor. Measurements were done by 6 different smartphones of 3 different producers, which makes those measurements unique as accuracies achieved...