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Tytuł:
Biometric indicators of growth and development of Lolium perenne and Trifolium repens in terms of recultivation of soil contaminated with petroleum
Autorzy:
Pawluśkiewicz, Bogumiła
Małuszyńska, Ilona
Małuszyński, Marcin
Dąbrowski, Piotr
Gnatowski, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/2203569.pdf
Data publikacji:
2022
Wydawca:
Instytut Technologiczno-Przyrodniczy
Tematy:
germination dynamic
Gompertz regression model
lawn plants
polycyclic aromatic hydrocarbons
PAH
pot tests
remediation
seedlings parameters
Opis:
The aim of the research was to determine the factors defining the growth and development of Lolium perenne and Trifolium repens upon petroleum contamination. The top layer of clay soil contaminated with petroleum products resulting from an oil pipeline failure was collected for the tests. The control was the same type of uncontaminated soil with the addition of, under laboratory conditions, tissue paper. The research was conducted in two stages. The first concerned the germination process and seedlings parameters (Petri dishes). The germination energy (GE) and the germination capacity (GC) of seeds were determined. The seedling’s development was also evaluated based on ‘WinRhizo PRO 2009’ software. Then, in the second stage, pot tests were carried out, where the growth and development of species in the first year after sowing were temporarily measured. The parameters studied were the number, height, green and dry masses of the plants. A Gompertz regression model describing seed species germination and number species as time dependent dynamic was applied. The data were analysed statistically using variance analysis (ANOVA) and the PCA (principal component analysis) method. The results of our study indicated that admixture of petroleum into the soil does not seriously affect the development dynamics of Lolium perenne seedlings. The diesel oil contamination mostly affects the germination of the Trifolium repens by a statistically significant increase of the maximum value of germination and increasing the maximum growth rate.
Źródło:
Journal of Water and Land Development; 2022, Special Issue; 70--79
1429-7426
2083-4535
Pojawia się w:
Journal of Water and Land Development
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic control of discharge energy during wedm for the purpose of eliminating vibrations of the wire tool electrode
Autorzy:
Straka, Ľuboslav
Kuchta, Patrik
Powiązania:
https://bibliotekanauki.pl/articles/2037395.pdf
Data publikacji:
2021
Wydawca:
STE GROUP
Tematy:
acoustic emission
dynamic control
Main Technological Parameters
MTP
Wire Electrical Discharge Machining
WEDM
Wire Tool Electrode
WTE
Opis:
Production in all industry fields is currently affected by new scientific and technical knowledge and the requirements for its rapid deployment. In many cases, the most modern and highly sophisticated technical systems are applied. Simultaneously, fully automated production systems are rather successfully used and progressive production technologies are implemented. In most cases, there is an integral part of a management system that operates the challenging technological processes. These processes would not be executable without the system's precise control, which provides a suitable precondition for ensuring the high quality of manufactured products. However, the customer's demanding requirements are not always met. These involve increased requests for the quality of the final product due to the reduction of the tolerance band and application of high-strength materials. This paper aims to describe one of the solutions by which it is possible to achieve a higher quality of the machined surface after wire electrical discharge machining (WEDM). The solution proposes that through dynamic management, the WEDM process eliminates the vibrations of the wire tool electrode and thereby achieves a substantial increase in the quality of the eroded area in terms of its geometric accuracy. With the support of an extensive database of information with precise exchange of information, the proposed system will allow to control the electro discharge process with regard to the optimal way of operation of the electro discharge machine on the basis of individually selected conditions.
Źródło:
Management Systems in Production Engineering; 2021, 4 (29); 260-265
2299-0461
Pojawia się w:
Management Systems in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic elastic properties of the hard coal seam at a depth of around 1260 m
Dynamiczne sprężyste właściwości pokładu węgla na głębokości około 1260 m
Autorzy:
Krawiec, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/1849546.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
dynamic elastic parameters
coal seam
P-wave velocity
S-wave velocity
seismic profiling
dynamiczne parametry sprężyste
pokład węgla
prędkość fali P
prędkość fali S
profilowanie sejsmiczne
Opis:
The knowledge of the dynamic elastic properties of a coal seam is important in the context of various types of calculations of the seam behavior under various stress-strain conditions. These properties are often used in numerical and analytical modeling related to maintaining the stability of excavations and the analysis of mechanisms, e.g. related to the risk of rock bursts. Additionally, during the implementation of seismic surveys, e.g. seismic profiling and seismic tomography in coal seams, the reference values of the elastic properties of coal are used in the calculation of relative stresses in various geological and mining conditions. The study aims to calculate the dynamic elastic parameters of the coal seam located at a depth of 1,260 m in one of the hard coal mines in the Upper Silesian Coal Basin (USCB). Basic measurements of the velocity of P- and S-waves were conducted using the seismic profiling method. These surveys are unique due to the lack of the velocity wave values in the coal seam at such a great depth in the USBC and difficult measurement conditions in a coal mine. As a result, dynamic modulus of elasticity was calculated, such as Young’s modulus, volumetric strain modulus, shear modulus and Poisson’s ratio. The volumetric density of coal used for calculations was determined on the basis of laboratory tests on samples taken in the area of the study. The research results showed that the calculated mean P-wave velocity of 2,356 m/s for the depth of 1,260 m is approximately consistent with the empirical relationship obtained by an earlier study. The P-wave velocity can be taken as the reference velocity at a depth of approx. 1,260 m in the calculation of the seismic anomaly in the seismic profiling method.
Znajomość dynamicznych właściwości sprężystych pokładu węgla jest istotna w kontekście różnego rodzaju obliczeń zachowania się pokładu w różnorakich warunkach naprężeniowo-odkształceniowych. Właściwości te są często wykorzystywane w modelowaniach numerycznych i analitycznych związanych z utrzymaniem stateczności wyrobisk oraz analizą mechanizmów, np. związanych z zagrożeniem tąpaniami. Dodatkowo w trakcie realizacji badań sejsmicznych np. profilowań sejsmicznych i tomografii sejsmicznej w pokładach węgla referencyjne wartości właściwości sprężyste węgla wykorzystywane są w obliczaniach naprężeń względnych w różnych warunkach geologiczno-górniczych. Celem badań jest obliczenie dynamicznych sprężystych parametrów pokładu węgla, położonego na głębokości około 1260 m, w jednej z kopalń węgla kamiennego w Górnośląskim Zagłębiu Węglowym. Podstawowe pomiary prędkości fal sejsmicznych wykonano metodą profilowania sejsmicznego. Te pomiary są unikatowe ze względu na dużą głębokość położenia profilu pomiarowego oraz trudne warunki pomiarowe w kopalni. W efekcie obliczono dynamiczne moduły sprężystości takie jak: moduł Younga, moduł odkształcenia objętościowego, moduł odkształcenia postaciowego oraz współczynnik Poissona. Gęstość objętościową węgla przyjętą do obliczeń wyznaczono na podstawie testów laboratoryjnych na próbach pobranych w rejonie badań. Wyniki badań pokazały, że obliczona średnia prędkość fali P równa 2356 m/s dla głębokości 1260 m jest w przybliżeniu zgodna z empirycznymi zależnościami określonymi we wcześniejszych badaniach. Prędkość fali P może być przyjęta jako prędkość odniesienia na głębokości około 1260 m w obliczeniach anomalii sejsmicznej w metodzie profilowania sejsmicznego.
Źródło:
Gospodarka Surowcami Mineralnymi; 2021, 37, 3; 159-176
0860-0953
Pojawia się w:
Gospodarka Surowcami Mineralnymi
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic handwritten signature identification using spiking neural network
Dynamiczna identyfikacja podpisu odręcznegoprzy użyciu pulsującej sieci neuronowej
Autorzy:
Kutsman, Vladislav
Kolesnytskyj, Oleh
Powiązania:
https://bibliotekanauki.pl/articles/2070220.pdf
Data publikacji:
2021
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
online signature identification
spiking neural network
invariant dynamic parameters
signature recognition
identyfikacja podpisu online
pulsująca sieć neuronowa
niezmienne parametry dynamiczne
rozpoznawanie podpisu
Opis:
The article proposes a method for dynamic signature identification based on a spiking neural network. Three dynamic signatureparameters l(t), xy(t), p(t) are used, which are invariant to the signature slope angle, and after their normalization, also to the signature spatial and temporal scales. These dynamic parameters are fed to the spiking neural network for recognition simultaneously in the form of time series without preliminary transformation into a vector of static features, which, on the one hand, simplifies the method due to the absence of complex computational transformation procedures,and on the other hand, prevents the loss of useful information, and therefore increases the accuracy and reliability of signature identificationand recognition (especially when recognizing forged signatures that are highly correlated with the genuine). The spiking neural network used has a simple training procedure, and not all neurons of the network are trained, but only the output ones. If it is necessary to add new signatures, it is not necessaryto retrain the entire network as a whole, but it is enough to add several output neurons and learn only their connections. Inthe results of experimental studies of the software implementation of the proposed system, it’s EER = 3.9% was found when identifying skilled forgeries and EER = 0.17% when identifying random forgeries.
W artykule zaproponowano metodę dynamicznej identyfikacji podpisów opartą na pulsującej sieci neuronowej. Wykorzystywane są trzy parametry dynamiczne podpisu l(t), xy(t), p(t), które są niezmienne względem kąta nachylenia podpisu, a po ich normalizacji –także do skali przestrzennej i czasowej podpisu. Te dynamiczne parametry są podawane do sieci neuronowej w celu rozpoznania jednocześnie jako szeregi czasowe bez uprzedniej konwersji na wektor cech statycznych, co z jednej strony upraszcza metodę ze względu na brak skomplikowanych procedur konwersji obliczeniowej,a z drugiej ręka zapobiega utracie przydatnych informacji –zwiększa dokładność i wiarygodność identyfikacjii rozpoznawania podpisów (zwłaszczaw rozpoznawaniu podpisów sfałszowanych, które są silnie skorelowane z autentycznymi).Zastosowana sieć neuronowa typu spiking ma prostą procedurę treningu, przy czym nie wszystkie neurony sieci są trenowane, a jedynie te wyjściowe.Jeśli konieczne jest dodanie nowych sygnatur, nie jest konieczne trenowanie całej sieci, ale wystarczy dodać kilka neuronów wyjściowych i uczyć tylko te połączenia.W wyniku eksperymentu programowego zaproponowanego systemu otrzymano EER = 3,9% przy identyfikacji sfałszowanych podpisów i EER = 0,17% przy identyfikacji fałszerstw losowych.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2021, 11, 3; 34--39
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of a mass variable drum winding a heavy rope
Autorzy:
Buśkiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/38629421.pdf
Data publikacji:
2021
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
angular momentum
two time parameters method
time-variable mass
dynamic equations
drum
Opis:
The paper focuses on a winch drum winding a heavy rope to present the variety of issues related to the dynamics of systems with rotating parts of time-varying mass. The dynamic motion equations for such systems are frequently either incorrect or derived under the assumption of mass constancy. When the mass variability is taken into account, simpler cases are discussed. The considerations on the angular momentum theorem enables formulating a new two time parameters form of the rotational motion equation for the system with time varying mass. Four cases are considered and different approaches of motion equations derivation are applied. The assumptions and solution methods of the analyzed systems as well as ambiguities and possible contradictions that may arise as a result of the trial of the problem formulation on the grounds of rigid body mechanics are discussed. The numerical simulations are presented.
Źródło:
Archives of Mechanics; 2021, 73, 5-6; 557-582
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Longitudinal automatic carrier-landing control law rejecting disturbances and coupling based on adaptive dynamic inversion
Autorzy:
Wang, Lipeng
Zhang, Zhi
Zhu, Qidan
Wen, Zixia
Powiązania:
https://bibliotekanauki.pl/articles/2090730.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
carrier-based aircraft
automatic landing
nonlinear dynamic inversion
lateral decoupling
parameters adaptation
statki powietrzne bazujące na lotniskowcach
automatyczne lądowanie
inwersja dynamiczna nieliniowa
odsprzęganie boczne
dostosowanie parametrów
Opis:
The longitudinal automatic carrier landing system (ACLS) control law is designed based on nonlinear dynamic inversion (NDI), which can reject air wake, decouple lateral states, and track the dynamic desired touchdown point (DTP). First of all, the nonlinear landing model of F/A−18 aircraft in the final approach is established, in which the parameters of the aerodynamic, control surfaces, and limited states are acquired. Second, the strategy of tracking the desired longitudinal trajectory through pitch angle control is adopted. The automatic power compensation system (APCS), pitch angle rate, pitch angle, and vertical position control loops are developed based on the adaptive NDI. The stable analysis and the principal description are derived in detail. Deck motion compensation (DMC) algorithm is designed by frequency response method. Third, the control parameters are optimized through the genetic algorithm. A fitness function integrated with velocity, angle of attack (AOA), pitch rate, pitch angle, and vertical position of the aircraft are proposed. Finally, integrated simulations are conducted on a semi-physical simulation platform. The results indicate that the adopted automatic landing control law can achieve both excellent performance and the ability to reject the air wake and lateral coupling.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; e136217, 1--10
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Longitudinal automatic carrier-landing control law rejecting disturbances and coupling based on adaptive dynamic inversion
Autorzy:
Wang, Lipeng
Zhang, Zhi
Zhu, Qidan
Wen, Zixia
Powiązania:
https://bibliotekanauki.pl/articles/2173584.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
carrier-based aircraft
automatic landing
nonlinear dynamic inversion
lateral decoupling
parameters adaptation
statki powietrzne bazujące na lotniskowcach
automatyczne lądowanie
inwersja dynamiczna nieliniowa
odsprzęganie boczne
dostosowanie parametrów
Opis:
The longitudinal automatic carrier landing system (ACLS) control law is designed based on nonlinear dynamic inversion (NDI), which can reject air wake, decouple lateral states, and track the dynamic desired touchdown point (DTP). First of all, the nonlinear landing model of F/A−18 aircraft in the final approach is established, in which the parameters of the aerodynamic, control surfaces, and limited states are acquired. Second, the strategy of tracking the desired longitudinal trajectory through pitch angle control is adopted. The automatic power compensation system (APCS), pitch angle rate, pitch angle, and vertical position control loops are developed based on the adaptive NDI. The stable analysis and the principal description are derived in detail. Deck motion compensation (DMC) algorithm is designed by frequency response method. Third, the control parameters are optimized through the genetic algorithm. A fitness function integrated with velocity, angle of attack (AOA), pitch rate, pitch angle, and vertical position of the aircraft are proposed. Finally, integrated simulations are conducted on a semi-physical simulation platform. The results indicate that the adopted automatic landing control law can achieve both excellent performance and the ability to reject the air wake and lateral coupling.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 1; art. no. e136217
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New generation of fencing structures - dynamic/adaptive facades. Prospects of the use in Russia
Autorzy:
Spiridonov, Alexander
Shubin, Igor
Gerashchenko, Roman
Powiązania:
https://bibliotekanauki.pl/articles/2065643.pdf
Data publikacji:
2021
Wydawca:
Politechnika Częstochowska
Tematy:
fasady bioklimatyczne
fasady energetyczne
koncentratory światła
fasady sceniczne
fasada dynamiczna
energooszczędność
parametry mikroklimatu
bioclimatic facades
energy facades
light concentrators
stage facades
dynamic facades
energy saving
microclimate parameters
Opis:
Based on a review and analyses of new technology and solutions in modern facade structures, a classification of a new generation of facades has been carried out. There are five main classes of facade: “Bioclimatic” (or “green”); “Energy”; “Light concentrators”; “Scenic” (or “architectural”); and “Dynamic” (or “adaptive”). Their distinctive features are given in the article. The most common examples of facades from various classes are considered. An assessment was made on the prospects for using the new generation facades in Russia.
Źródło:
Budownictwo o Zoptymalizowanym Potencjale Energetycznym; 2021, 10, 1; 135--144
2299-8535
2544-963X
Pojawia się w:
Budownictwo o Zoptymalizowanym Potencjale Energetycznym
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Gas-Geodynamic Phenomena During the Preparatory and Mining Works in Seam 358/1 at KWK “Budryk”
Autorzy:
Zmarzły, Marian
Schubert, Michał
Salamon, Krystian
Powiązania:
https://bibliotekanauki.pl/articles/2064263.pdf
Data publikacji:
2020
Wydawca:
STE GROUP
Tematy:
outbursts of methane
outbursts of coal
methane hazard
gas-dynamic phenomena
transient states of air parameters
mine monitoring systems
zjawiska gazodynamiczne
stany nieustalone parametrów powietrza
zagrożenie metanowe
wyrzuty metanu
wyrzuty węgla
monitoring kopalń
Opis:
The nature of gas-geodynamic phenomena is so complicated and unpredictable that it forces the necessity of continuous search for new principles of identifying the outburst threat and ongoing monitoring of this threat with view of current conditions in the mine. After the incidents in JSW S.A, the mines carrying out works in seams threatened with outbursts, upon their own initiative introduced additional rigours and increased the frequency of measurements and tests regardless of the existing legal requirements. Incidents that have taken place in KWK “Budryk” in recent years show how important is continuous verification of knowledge related to the forecasting of the outburst threat on the basis of ongoing observations of works. The local occurrence of a zone characterized by high methane-bearing capacity in the coal seam, even after taking preventive measures and introducing additional rigorous did not allow for the complete elimination of gas-geodynamic phenomena and avoidance of danger to employed people.
Źródło:
New Trends in Production Engineering; 2020, 3, 1; 131--148
2545-2843
Pojawia się w:
New Trends in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification and verification of dynamic parameters for the welding manipulator
Autorzy:
Jírová, Radka
Pešík, Lubomír
Powiązania:
https://bibliotekanauki.pl/articles/196834.pdf
Data publikacji:
2020
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
dynamic parameters
dynamic system
welding production line
welding manipulator
linear guiding system
parametry dynamiczne
system dynamiczny
linia do spawania
manipulator spawalniczy
system prowadzenia liniowego
Opis:
Welding production lines are indispensable parts of the production processes in the automotive industry. In many cases, the production line operation is ensured by equipment with linear conveyors or robots, wherein linear guiding systems are basic elements of these manipulators. The failure of some linear guiding system may lead to significant production losses. Hence, the knowledge of their operating loads is necessary to determine very exactly. The objective of this article is to identify and verify the basic dynamic parameters of the welding manipulator, as a starting point for the operating loads calculation of linear guiding systems. This issue was solved by combining the measurement of kinematic values and MBS (Multi-body System) analysis in case of the concrete linear welding manipulator, which was the main part of the observed welding line. We have measured time values of acceleration in defined points of the manipulator and evaluated them by FIR (Finite Impulse Response) filter, FFT (Fast Fourier Transformation) analysis and ODS (Operating Deflection Shapes) analysis. The obtained frequency spectrum showed oscillation frequencies, which could be compared with frequencies of the manipulator dynamical model by different mass and stiffness parameters. In this way, the dynamic parameters of the welding manipulator can be identified and used for the next calculations and simulations, where loads of linear guiding systems will produce very important results.
Źródło:
Zeszyty Naukowe. Transport / Politechnika Śląska; 2020, 106; 51-61
0209-3324
2450-1549
Pojawia się w:
Zeszyty Naukowe. Transport / Politechnika Śląska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of the parameters of vibrations during dynamic balancing of the fan rotor according to Polish and International Standards
Autorzy:
Śloderbach, Z.
Powiązania:
https://bibliotekanauki.pl/articles/947331.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
parametry drgań
wirnik wentylatora
normy ISO
wyważanie dynamiczne
parameters of vibrations
ISO standards
fan rotor
dynamic forces
dynamic balancing
Opis:
In the paper a procedure and methodology of acceptable calculations of powers, displacements (of amplitudes) and velocities of pulses according to ISO standards depending on the rotational speeds (frequencies) of rotor during attempts of dynamic breaking down taking into account effectiveness of vibration isolation were described. The proposed method is regarding one-sidedly hung rotors appearing in such appliances as rotors of fans, blowers, pumps and others. As permissible parameters of pulses values which are given in international standards PN-ISO-10816-1:1998P and PN-ISO-7919-1:2001 were assumed. Calculations were compared in the form of tables and they depicted with relevant graphs which have the character of useful nomograms. Also, recommendations for the design of the foundations and guidelines related to dimensions of the foundation, the weight and the way of fixing the device were given. In the end also closing remarks and conclusions were given.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 2; 473-483
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study of the nonlinear dynamics of a smooth and discontinuous oscillator with different smoothness parameters and initial values
Autorzy:
Chang, Yujian
Chen, Enli
Feng, Ming
Powiązania:
https://bibliotekanauki.pl/articles/281961.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
SD oscillator
experimental system
nonlinear dynamic characteristic
initial value sensitivity
smoothness parameters
Opis:
The dynamic response of a nonlinear system is very sensitive to initial conditions. Both the irrational nonlinearity and the large displacement of a smooth and discontinuous (SD) oscillator have been studied in this paper. An experimental study has been conducted on a model of the SD oscillator with different initial conditions and smoothness parameters. Experimental results indicate that tiny variation in the initial displacement will lead to different kinds of vibrations, and the system exhibits a wide range of nonlinear dynamical phenomena with the change of smoothness parameters. All experimental results are in good conformity with numerical simulation results.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 4; 935-946
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of the effects of flat cushioning insole on gait parameters in individuals with chronic neck pain
Autorzy:
Kirmizi, Muge
Simsek, Ibrahim Engin
Elvan, Ata
Akcali, Omer
Angin, Salih
Powiązania:
https://bibliotekanauki.pl/articles/306371.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ból szyi
parametry chodu
siła reakcji podłoża
obciążenie dynamiczne
amortyzacja
chronic neck pain
flat cushioning insole
gait parameters
ground reaction force
dynamic loading
shock absorption
Opis:
Individuals with chronic neck pain (CNP) walk with a stiffer spine known to cause an increase in dynamic loading on the spine. They also exhibit altered spatiotemporal gait variables, however, it is still unclear whether flat cushioning insole, which reduces dynamic loading on the musculoskeletal system by absorbing the ground reaction force, affects gait parameters in individuals with CNP. The aim of this work was to investigate the effects of flat cushioning insole on neck pain during walking and gait parameters in individuals with CNP. Methods: Twenty-one individuals with CNP and 21 asymptomatic controls were included. Assessments of gait parameters and pain were conducted in two sessions, standard shoe only and standard shoe with flat cushioning. In both sessions, all participants performed the 10-meter walk test in two walking conditions: preferred walking, walking at maximum speed. The force sensitive insoles and the video analysis method were used to assess plantar pressure variables and spatiotemporal gait variables, respectively. Pain was assessed using the Visual Analogue Scale. Results: Our results indicated that flat cushioning reduced the maximum force and force-time integral in both groups ( p < 0.05). Flat cushioning increased walking speed and step length in both walking conditions and reduced neck pain during walking at maximum speed in individuals with CNP ( p < 0.05). In asymptomatic individuals, no difference was found in spatiotemporal gait variables between two sessions ( p > 0.05). Conclusions: These results have suggested that the use of flat cushioning insole may improve neck pain during walking and spatiotemporal gait variables in individuals with CNP.
Źródło:
Acta of Bioengineering and Biomechanics; 2019, 21, 2; 135-141
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some effects of wind on ship’s manoeuvrability
Autorzy:
Szymoński, M.
Powiązania:
https://bibliotekanauki.pl/articles/117192.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
ship’s manoeuvrability
effects of wind
wind resistance
wind speed
windage area
wind pressure force
manoeuvring characteristics
dynamic parameters
Opis:
All ships experience an air and wind resistance while under way of sea, and they may experience adverse effects on wind while manoeuvring in harbours and limited waterways. The wind resistance is proportional to relative wind speed squared, wind direction and the projected windage area of the ship. The paper describes the effect of wind pressure into the ship’s superstructures and houses on ship manoeuvrability, in the range of the wind speed, for the ship which is with the large windage area. The above is one of the recommended information to be included in the ship’s manoeuvring booklet, as per IMO Resolution A.601(15). In sea practice, the manoeuvring characteristics in wind, as wind forces and moments, course-keeping limitation, and drifting under wind influence are fare from these estimated. The results obtained during the several years of practice in ship’s exploitation are included in this paper.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2019, 13, 3; 623-626
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of speed dependent fault parameters in a coupled rotor-bearing system
Autorzy:
Lal, M.
Satapathy, M.
Powiązania:
https://bibliotekanauki.pl/articles/140014.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
speed-dependent dynamic parameters
rotor-bearing-coupling
misalignment
analytical approach
multiple faults
Lagrange's method
parametry dynamiczne zależne
wirnik-łożysko-sprzęgło
niewspółosiowość
podejście analityczne
błędy wielokrotne
metoda Lagrange'a
Opis:
In rotating machineries, misalignment is considered as the second most major cause of failure after unbalance. In this article, model-based multiple fault identification technique is presented to estimate speed-dependent coupling misalignment and bearing dynamic parameters in addition with speed independent residual unbalances. For brevity in analysis, a simple coupled rotor bearing system is considered and analytical approach is used to develop the identification algorithm. Equations of motion ingeneralized co-ordinates are derived with the help of Lagrange’s equation and least squares fitting approach is used to estimate the speed-dependent fault parameters. Present identification algorithm requires independent sets of forced response data which are generated with the help of different sets of trial unbalances. To avoid/suppress the ill-conditioning of regression equation, independent sets of forced response data are obtained by rotating the rotor in clock-wise and counter clock-wise directions, alternatively. Robustness of algorithm is checked for different levels of measurement noise.
Źródło:
Archive of Mechanical Engineering; 2018, LXV, 3; 327-347
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
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