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Tytuł:
Experimental and theoretical study of the reinforced concrete flat slabs with the central support loss
Autorzy:
Tur, Viktar
Tur, Andrei
Lizahub, Aliaksandr
Powiązania:
https://bibliotekanauki.pl/articles/2172407.pdf
Data publikacji:
2022
Wydawca:
Centrum Rzeczoznawstwa Budowlanego Sp. z o.o.
Tematy:
flat slab
robustness
resistance mechanism
membrane action
dynamic resistance
energy balance method
płaska płyta
krzepkość
mechanizm oporowy
działanie membranowe
opór dynamiczny
metoda bilansu energetycznego
Opis:
The paper experimentally and theoretically considers the issues of assessing the robustness and resistance to progressive collapse of a flat slab with a sudden removal of the central support. The results of testing two scale models of a fragment of a flat ceiling in the case of removal of the central support under static (specimen FS-1) and dynamic (specimen FS-2) loading are presented and analyzed. A theoretical approach to the quantitative assessment of robustness was tested, which is based on the provisions of the energy balance of a damaged structural system in an accidental design situation.
Źródło:
Inżynieria Bezpieczeństwa Obiektów Antropogenicznych; 2022, 4; 12--41
2450-1859
2450-8721
Pojawia się w:
Inżynieria Bezpieczeństwa Obiektów Antropogenicznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effects of Different Exercise Intensities on the Static and Dynamic Balance of Older Adults: A randomised Controlled Trial
Autorzy:
Ghasemabad, Kamran
Kamalden, Tengku
Dev, Roxana
Gasibat, Qais
Nekooei, Pooya
Majlesi, Sara
Nekouei, Paria
Alemi, Behzad
Powiązania:
https://bibliotekanauki.pl/articles/2148827.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Szczeciński. Wydawnictwo Naukowe Uniwersytetu Szczecińskiego
Tematy:
elderly
resistance training
high-intensity training
moderate-intensity training
low-intensity training
static balance
dynamic balance
Opis:
This study aims to find the effectiveness of different exercise intensities (high-, moderate-, and low-intensity) on the dynamic and static balance of elderly women. A single-blinded factorial design study was conducted in healthy older adults (>65 years) in 12 weeks. The authors have assessed the Forward Reach Test (FRT), Lateral Reach Test (LRT), One Leg Stand (OLS), Tandem Stand Test (TST) in 60 healthy older women at a gym centre, Fit House located in Bukit Rimau, Kuala Lumpur, Malaysia. Participants were randomly assigned to a High-Intensity Training (HIT) group; (n=15) (Mean age 69.60 ± 3.68) who performed four exercises [Leg Press (LP), Leg Extension (LE), Leg Curl (LC), and Calf Raises (CR)] at 80 to 90% of One-Repetition Maximum (1RM); Moderate-Intensity Training (MIT) group (n=15) (Mean age 69.27 ± 3.41) performed at 65 to 75% of 1RM; Low- Intensity Training (LIT) group (n=15) (Mean age 69.27 ± 1.94) performed at 50 to 60% of 1 RM; and a Control Group (CG) (n = 15) (Mean age 68.67 ± 2.38) with no training. Data was collected at pre-test, 4th, 8th, and 12th weeks of intervention. 60 participants were analysed and the main effect of time showed a statistically significant difference in the mean of all variables (all p < 0.001), and also there was a statistically significant interaction between intervention and time on all variables (all p < 0.001). Different levels of intensity on only the lower extremities muscles had a significant effect on the dynamic balance and static balance of the elderly population. After four weeks of training HIT, MIT, and LIT illustrated significant improvement in dynamic balance, as well as static balance.
Źródło:
Central European Journal of Sport Sciences and Medicine; 2022, 39; 49-64
2300-9705
2353-2807
Pojawia się w:
Central European Journal of Sport Sciences and Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A mathematical model of two-stage Solid Oxide Fuel Cell, SOFC, stacks for dynamic simulation of Combined Heat and Power system fed by natural gas
Autorzy:
Palus, Mateusz
Pianko-Oprych, Paulina
Powiązania:
https://bibliotekanauki.pl/articles/1849273.pdf
Data publikacji:
2021
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
dynamic model
natural gas
Solid Oxide Fuel Cell stacks
Combined Heat and Power
CHP
system
Balance of Plant
BoP
modelling
Catalytic Partial Oxidation
CPOx
reformer
steam reformer
Opis:
Zero-dimensional two-stage SOFC stacks dynamic model was developed to investigate the effect of operating parameters on stacks performance. The model resolves spatially thermal and thermo-electrochemical behaviour for electrochemical reactions, Catalytic Partial Oxidation and Steam Reforming processes. Design variables and thermo-electrochemical properties were obtained from in-house-fabricated SOFCs carried out by project partners. The completed SOFCs based Combined Heat and Power, CHP, system model was validated by data18 and numerical results obtained at steady-state mode showing its high-fidelity. A parametric study with respect to key operating parameters including changes in fuel utilization, lambda number and current density values was conducted. The global CHP system dynamic response, in term of the current/voltage delivered by two-stage SOFC stacks, under a fi xed fuel utilization, has been determined resulting in greater variations in the voltage of a single cell in the first stack in comparison to the corresponding values in the second stack.
Źródło:
Polish Journal of Chemical Technology; 2021, 23, 2; 1-11
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A mathematical model of two-stage Solid Oxide Fuel Cell, SOFC, stacks for dynamic simulation of Combined Heat and Power system fed by natural gas
Autorzy:
Palus, Mateusz
Pianko-Oprych, Paulina
Powiązania:
https://bibliotekanauki.pl/articles/1849268.pdf
Data publikacji:
2021
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
dynamic model
natural gas
Solid Oxide Fuel Cell stacks
Combined Heat and Power
CHP
system
Balance of Plant
BoP
modelling
Catalytic Partial Oxidation
CPOx
reformer
steam reformer
Opis:
Zero-dimensional two-stage SOFC stacks dynamic model was developed to investigate the effect of operating parameters on stacks performance. The model resolves spatially thermal and thermo-electrochemical behaviour for electrochemical reactions, Catalytic Partial Oxidation and Steam Reforming processes. Design variables and thermo-electrochemical properties were obtained from in-house-fabricated SOFCs carried out by project partners. The completed SOFCs based Combined Heat and Power, CHP, system model was validated by data18 and numerical results obtained at steady-state mode showing its high-fidelity. A parametric study with respect to key operating parameters including changes in fuel utilization, lambda number and current density values was conducted. The global CHP system dynamic response, in term of the current/voltage delivered by two-stage SOFC stacks, under a fi xed fuel utilization, has been determined resulting in greater variations in the voltage of a single cell in the first stack in comparison to the corresponding values in the second stack.
Źródło:
Polish Journal of Chemical Technology; 2021, 23, 2; 1-11
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling damaged precast structural system when its robustness check
Autorzy:
Tur, Viktar
Tur, Andrei
Lizahub, Aliaksandr
Powiązania:
https://bibliotekanauki.pl/articles/1819317.pdf
Data publikacji:
2021
Wydawca:
Centrum Rzeczoznawstwa Budowlanego Sp. z o.o.
Tematy:
robustness
resistance mechanism
progressive collapse
dynamic resistance
energy balance method
EBM
krzepkość
mechanizm oporowy
postępujące zawalenie
opór dynamiczny
metoda bilansu energetycznego
Opis:
Within the framework of traditional approaches to checking for resistance of reinforced concrete buildings and structures to the progressive collapse development, membrane (chain) forces in a damaged structural system are calculated separately, without considering its non-linear bending behavior during the formation of the plastic hinges and without checking the possibility of achieving large deflections. The authors propose an approach to modelling a nonlinear quasi-static reaction of a damaged structural system in an accidental design situation. This approach considers non-linear bending and the resistance of reserved horizontal ties, considering their ultimate ductility. The authors verified the proposed approach based on the results of experimental studies by others researchers. An example of the application of the proposed approach in assessing the robustness of a structural system made of precast concrete with a sudden removal of the central column is considered. In accordance with the provisions of the energy approach, an analysis is made of the contribution of individual resistance mechanisms to the total quasi-static and dynamic resistance of the damaged structural system. We show that the proposed calculation model adequately describes the behavior of a damaged structural system in an accidental design situation, and therefore to carry out parametric studies and check the robustness of building structures.
Źródło:
Inżynieria Bezpieczeństwa Obiektów Antropogenicznych; 2021, 3; 63--81
2450-1859
2450-8721
Pojawia się w:
Inżynieria Bezpieczeństwa Obiektów Antropogenicznych
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research of rotary piston engine use in transport power plants
Autorzy:
Mytrofanov, Oleksandr
Proskurin, Arkadii
Poznanskyi, Andrii
Powiązania:
https://bibliotekanauki.pl/articles/2203852.pdf
Data publikacji:
2021
Wydawca:
Politechnika Śląska. Wydawnictwo Politechniki Śląskiej
Tematy:
rotary piston air engine
hybrid transport power plant
compressed air
external speed characteristics
car power balance
dynamic characteristic of a car
silnik powietrzny z tłokiem obrotowym
sprężone powietrze
charakterystyka prędkości zewnętrznej
bilans mocy samochodu
charakterystyka dynamiczna samochodu
Opis:
A schematic diagram of a transport hybrid power plant using a new design RPE-4.4/1.75 rotary piston air engine is proposed. Its external speed characteristic is determined, according to which the maximum engine power is 8.75 kW at 850 rpm and the maximum torque is 127.54 N∙m at 400 rpm. For various gears and speeds, all the components of the power balance were determined and the dynamic characteristic of the hybrid car was obtained when operated on an air engine. According to the dependences of the power balance, the total traction force from the rotary piston air engine on the driving wheels is 5 kN. The performance of acceleration of a hybrid car while working on an air engine is estimated, namely, the dependences of acceleration, time, and acceleration path are obtained. In urban traffic, the required time to accelerate the car to a speed of 60 km/h is 15.2 s and the path is 173 m. The possible drive range of the hybrid car on compressed air without additional recharging is analyzed. On one cylinder with compressed air with a volume of 100 liters, an initial pressure of 35 MPa, and a final pressure of 2 MPa, the hybrid car can travel about 26 km.
Źródło:
Transport Problems; 2021, 16, 1; 165--178
1896-0596
2300-861X
Pojawia się w:
Transport Problems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simplified analytical method for the robustness assessment of precast reinforced concrete structural systems
Autorzy:
Tur, Viktar
Tur, Andrei
Lizahub, Aliaksandr
Powiązania:
https://bibliotekanauki.pl/articles/1955933.pdf
Data publikacji:
2021
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
robustness
dynamic resistance
ties
energy balance method
membrane effect
Opis:
The article presents the simplified implementation of alternative load path method based on the energy balance approach. This method should be used to check the global resistance of a damaged structural system after the occurrence of an accidental event. Basic assumptions of simplified analytical models for modelling resistance of horizontal ties in a damaged structural system, taking into account the membrane (chain) effects, were presented. An approach to modelling the dynamic resistance of a damaged structural system based on the energy balance method is described. Calculated dependencies for checking the robustness of a prefabricated multi-storey building with hollow-core slabs after the loss of the central column are proposed and considered using an example. On the considered example, a comparison of the required tie sections area with the dynamic resistance designed using the energy balance method (EBM) and according to the current standards, and a statistical assessment of the reliability of the load-bearing capacity models are carried out. In the end, a brief algorithm for the simplified calculation of the dynamic resistance of a damaged structural system is proposed.
Źródło:
Budownictwo i Architektura; 2021, 20, 4; 93-114
1899-0665
Pojawia się w:
Budownictwo i Architektura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The development of postural control in 6–17 old years healthy children. Part I Postural control evaluation in modified Clinical Test for The Sensory Interaction on Balance in 6–17 old year children (mctsib)
Autorzy:
Orendorz-Frączkowska, Krystyna
Kubacka, Marzena
Powiązania:
https://bibliotekanauki.pl/articles/1397293.pdf
Data publikacji:
2020
Wydawca:
Index Copernicus International
Tematy:
balance maturation
balance system in children
posturography
static and dynamic balance
vestibulospinal reflexes
Opis:
Introduction: Proper development of postural control in children is connected with the maturation of the central nervous system, development of sensory organisation with appropriate use of proprioceptive, visual, vestibular information as well as reactions and postural strategy which allow the maintenance of balance in changeable environmental conditions. Developmental disturbances in this particular area is reflected in postural disfunctions and the assessment of these disfunctions and disturbances needs referring to normative values of the healthy population of children. Aim: Examination of postural control development in children aged 6–17 years. Material: 127 healthy children were tested (65 girls and 62 boys) aged 6–17 years. Method: Laryngological investigation, medical history interview, audiometry and tympanometry were conducted in all children. In the evaluation of postural control (mCTSIB-modified Clinical Test For The Sensory Interaction On Balance) a computer posturography system was used (Balance Master Neurocom). R esults: Further development of postural control was found in healthy children up to the age of 13 years of age. The development was not linear but showed transient characteristics with a faster development stage between the age of 6–7 and 8–9. Better postural control in girls, particularly the youngest, in comparison with boys was noticed. C onclusions: 1. The values of norm postural control in posturographic test mCTSIB in children aged 6–17 was established. In this test postural control development was completed in children before 13 year and it was not linear. 2. Due to gender differences it seems appropriate to use separate norms in order to evaluate the development of postural control in boys and girls.
Źródło:
Polish Journal of Otolaryngology; 2020, 74, 1; 29-35
0030-6657
2300-8423
Pojawia się w:
Polish Journal of Otolaryngology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The development of postural control in 6–17 old years healthy children. Part II Postural control evaluation – Limits of Stability Test (LOS) in 6–17 old year children
Autorzy:
Orendorz-Frączkowska, Krystyna
Kubacka, Marzena
Powiązania:
https://bibliotekanauki.pl/articles/1397378.pdf
Data publikacji:
2020
Wydawca:
Index Copernicus International
Tematy:
balance maturation
balance system in children
limits of stability
posturography
static and dynamic balance
Opis:
Introduction: The ability to Reach quickly to changing external stimuli, to move the body quickly and precisely in any direction and to maintain the centre of gravity above the support base, all contribute to maintaining balance in dynamic conditions. The Limits of Stability Test (LOS) provides information on the state of dynamic equilibrium in a standing position. Aim : Assessment of dynamic postural control in developmental age. Material : 127 healthy children (65 girls and 62 boys) aged 6 – 17years. Methods: All children underwent LOS test (posturograph NeuroCom) with registration of reaction time (RT), movement velocity (MVL), directional control (DCL) , maximum excursion (MXE) and endpoint excursion (EPE). Results: At the age of 6-7 years, not fully developed jumping strategy and visual feedback mechanism in the control of movement were observed. All tested parameters were significantly worse in children aged 6 – 9 years. After this period, a significant improvement in TR and MVL was observed, with no significant changes in subsequent age groups while significant improvement in MXE up to 12 , EPE and DCL up to 13 years of age was noted. No significant gender differences were fund in the LOS test parameters. Conclusions: 1 The LOS test showed significantly lower dynamic balance development in children aged 6 – 7 years. 2 The study showed a significant improvement in all parameters of the LOS test up to 13 years of age, which supports the termination of the function at that time.
Źródło:
Polish Journal of Otolaryngology; 2020, 74, 4; 18-24
0030-6657
2300-8423
Pojawia się w:
Polish Journal of Otolaryngology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of dynamic balance exercises on certain kinematic variables and jump shoot accuracy among female basketball players
Autorzy:
Alhawary, Ranya
Powiązania:
https://bibliotekanauki.pl/articles/1902562.pdf
Data publikacji:
2020-03-30
Wydawca:
Politechnika Opolska. Wydział Wychowania Fizycznego i Fizjoterapii
Tematy:
dynamic balance
motion analysis
jump shoot
accuracy
basketball
Opis:
The aim of the research is to identify the impact of dynamic balance exercises on certain Kinematic Variables andJump Shoot Accuracy among Female Basketball Players. Researchers used the experimental method for one groupwith pre - post Tests. The research sample was intentionally selected for Female Basketball Players under the ageof 16 at the Beni Suef club registered in the Egyptian Basketball Federation for the 2019 sports season andtotalling ten (10) players who were filmed during the Jump Shoot after dribbling to recognize certain KinematicVariables that affect shooting accuracy. Researchers conducted tests of front and lateral balance using a (MFT)device, Hexagon Test, Vertical jump from motion and skill tests to measure the accuracy and speed of the shoot.The implementation of the training program was conducted for eight weeks - five units per week; the time of eachunit was 120 minutes, including 40 min. devoted to balance exercises. The main findings showed improvementin the results of balance tests using the (MFT)device, Hexagon, vertical jump from motion, and improvement inthe motion path of the centre of gravity for the horizontal and vertical paths. It also showed benefits for thehorizontal displacement transfer of Momentum to vertical motion energy which enabled the player to reach thehighest point, and improvement of shooting angles which is considered the main factor in giving the ball theright trajectory in order to enter the ring to improve the ratio of the jump shoot. Researchers recommended thenecessity of using dynamic balance exercises within Female training programs.
Źródło:
Journal of Physical Education & Health - Social Perspective; 2019, 8, 14; 41-48
2084-7971
Pojawia się w:
Journal of Physical Education & Health - Social Perspective
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of a serial connection of two staged SOFC stacks in a CHP system fed by methane using Aspen TECH
Autorzy:
Pianko-Oprych, Paulina
Palus, Mateusz
Powiązania:
https://bibliotekanauki.pl/articles/779502.pdf
Data publikacji:
2019
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
Solid Oxide Fuel Cell stacks
Combined Heat and Power system
Balance of Plant
BoP
modelling
methane
Catalytic Partial Oxidation
CPOx
reformer
steam reformer
part and full load
steady state
dynamic model
Opis:
The objective of the study was to develop a steady-state system model in Aspen TECH using user-defined subroutines to predict the SOFC electrochemical performance. In order to achieve high overall fuel utilization and thus high electrical efficiency, a concept of Combined Heat and Power system with two-stage SOFC stacks of different number of cells was analyzed. The concept of two-stage SOFC stacks based system was developed in the framework of the FP7 EU-funded project STAGE-SOFC. The model was validated against data gathered during the operation of the proof-of-concept showing good agreement with the comparative simulation data. Following model validation, further simulations were performed for different values of fuel utilization to analyze its influence on system electrical performance. Simulation results showed that the concept of two-stage SOFC stacks configuration was viable and reliable. The model can be useful for development the optimal control strategy for system under safe conditions.
Źródło:
Polish Journal of Chemical Technology; 2019, 21, 1; 33-43
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stabilność posturalna u piłkarzy nożnych z przewlekłą niestabilnością stawu skokowo-goleniowego
Postural stability in football players with chronic ankle instability
Autorzy:
Stefaniak, Wojciech
Bączkowicz, Dawid
Powiązania:
https://bibliotekanauki.pl/articles/2152223.pdf
Data publikacji:
2019-01-23
Wydawca:
Fundacja Edukacji Medycznej, Promocji Zdrowia, Sztuki i Kultury Ars Medica
Tematy:
kontrola posturalna
równowaga dynamiczna
skręcenie stawu skokowego
postural control
dynamic balance
ankle sprain
Opis:
Wstęp. Piłkarze nożni narażeni są na częste urazy supinacyjne stawu skokowo-goleniowego, który, wielokrotnie powtarzany, sprzyja powstaniu przewlekłej niestabilności (CAI). Dotychczasowe badania wskazują, iż CAI nie wpływa istotnie na stabilność posturalną w warunkach statycznych, jednakże istnieją przypuszczenia, że w warunkach dynamicznych może mieć istotne znaczenie. Z tego powodu celem naszych badań była analiza stabilności posturalnej w warunkach dynamicznych, z uwzględnieniem dominacji kończyny dolnej. Materiał i metody. W badaniu wzięło udział 28 piłkarzy nożnych (w wieku 26,1±5,4) zakwalifikowanych do grupy CAI zgodnie z kryteriami kwalifikacji International Ankle Consortium oraz 37 piłkarzy (w wieku 27,3±5,2), bez wcześniejszej historii urazu supinacyjnego, tworzących grupę kontrolną (CTRL). Do oceny stabilności posturalnej w pozycji stania obunóż oraz jednonóż w warunkach dynamicznych wykorzystano platformę Biodex Balance System. Wyniki. W postawie obunóż zaobserwowano różnice istotne statystycznie (p<0,05) między grupami CAI (OSI 7,01±2,43; APSI 5,18±1,85) i CTRL (OSI 5,27±1,42; APSI 3,98± 1,42). W postawie jednonóż zauważono podobne trendy, gdzie CAI uzyskała istotnie statystycznie (p<0,05) wyższe wyniki w analizowanych parametrach. Funkcja kończyny dolnej odgrywała istotną rolę w grupie CTRL w parametrach OSI (dom. 7,23±1,48; n-dom. 5,64±1,51) oraz MLSI (dom. 3,8±0,64; n-dom. 3.07±0,97). Wnioski. CAI upośledza stabilność posturalną u piłkarzy nożnych w warunkach dynamicznych zarówno w postawie obunóż, jak i jednonóż, jednakże funkcja kończyny dolnej istotnie wpływa na kontrolę posturalną jedynie w grupie CTRL.
Background. Football players are exposed to frequent supination injuries of the talocrural joint and repeated injuries lead to chronic ankle instability (CAI). Previous study results indicate that CAI do not significantly affect postural stability under static conditions, however, it is suspected that it may aggravate under dynamic conditions. Therefore, the goal of this study was analysis of postural stability under dynamic conditions with regard to dominance of the lower limb. Material and methods. The sample comprised 28 football players (age = 26.1±5.4), included in CAI group according to the Ankle Consortium inclusion criteria and 37 football players (age = 27.3±5.2) with no history of supination injuries, included in the control group (CTRL). Biodex Balance System platform was used for postural stability assessment during single leg standing under dynamic conditions. Results. During single leg standing statistically significant between-group differences were noted (p<0.05). The following values were obtained in CAI and CTRL groups respectively: CAI: (OSI 7.01±2.43; APSI 5.18±1.85), CTRL: (OSI 5.27±1.42; APSI 3.98±1.42). During single leg standing similar trends were observed. CAI group obtained statistically significant (p<0.05), higher values of the studied parameters. Lower limb function played an important role in CTRL group as for OSI (dom. 7.23±1.48; n-dom. 5.64±1.51) and MLSI (dom. 3.8±0.64; n-dom. 3.07±0.97) parameters. Conclusions. CAI impairs postural stability in footballers under dynamic conditions, both during single and double leg standing, however, the lower limb function significantly affects postural control only in CTRL group.
Źródło:
Polish Journal of Sports Medicine; 2018, 34(4); 239-245
1232-406X
2084-431X
Pojawia się w:
Polish Journal of Sports Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie czynnościowe osób z zawrotami głowy i zaburzeniami równowagi dla potrzeb medycyny pracy
Functional assessment of patients with vertigo and dizziness in occupational medicine
Autorzy:
Zamysłowska-Szmytke, Ewa
Szostek-Rogula, Sylwia
Śliwińska-Kowalska, Mariola
Powiązania:
https://bibliotekanauki.pl/articles/2162654.pdf
Data publikacji:
2018-03-09
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
awroty głowy
dynamiczny indeks chodu
wideonystagmografia
posturografia
Skala Równowagi Berg
zaburzenia równowagi
vertigo
dynamic gait index
videonystagmography
posturography
Berg Balance Scale
unbalance
Opis:
Wstęp W ocenie układu równowagi istotne znaczenie mają objawy, zaburzenia w badaniu klinicznym i czynnościowym oraz ich weryfikacja w testach obiektywnych. Celem pracy było określenie zgodności oceny kwestionariuszowej i funkcjonalnej z badaniami obiektywnymi. Materiał i metody Badaniem objęto 131 pacjentów poradni audiologicznej (średni wiek: 59±14 lat), w tym 101 kobiet. Wśród rozpoznań klinicznych dominowały łagodne położeniowe zawroty głowy, zawroty psychogenne i zawroty pochodzenia ośrodkowego. Objawy oceniano, korzystając z kwestionariusza dotyczącego ćwiczeń Cawthworne’a-Cookseya (CC), kwestionariusza DHI (Dizziness Handicap Inventory) i Skali Lęku-Depresji Duke’a. Do oceny czynnościowej zastosowano Skalę Równowagi Berg (Berg Balance Scale – BBS), dynamiczny indeks chodu (dynamic gait index – DGI), test Tinetti, test TUG (Timed Up and Go – „wstań i idź”) oraz test dynamicznej ostrości wzroku (DOW). Badania laboratoryjne obejmowały próbę kaloryczną i posturografię statyczną. Wyniki Wyniki BBS, DGI, TUG i DOW wykazały istotną statystycznie, lecz umiarkowaną zgodność z wynikami badań obiektywnych – zarówno próby kalorycznej (W Kendalla = 0,29), jak i posturografii statycznej (W = 0,33). Dla badań kwestionariuszowych zgodność ta była bardzo niska (W = 0,08–0,11). Wartości predykcyjne dodatnie dla skali BBS wynosiły 42% (próba kaloryczna) i 62% (posturografia), dla DGI odpowiednio: 46% i 57%. Wnioski Wyniki testów czynnościowych BBS, DGI, TUG i DOW wykazują istotną statystycznie zależność od badań obiektywnych, jednak niskie wartości predykcyjne nie pozwalają na zastosowanie tych testów jako screeningowych dla zaburzeń przedsionkowych. Jedynie połowa osób, u których stwierdzono zaburzenia funkcji układu równowagi w testach czynnościowych, ma nieprawidłowe wyniki próby kalorycznej i/lub posturografii statycznej. Kwalifikując do pracy na podstawie wyników badań obiektywnych, pomija się zaburzenia funkcjonalne, które mogą wpływać na zdolność do wykonywania pracy. Med. Pr. 2018;69(2):179–189
Background Balance assessment relies on symptoms, clinical examination and functional assessment and their verification in objective tests. Our study was aimed at calculating the assessment compatibility between questionnaires, functional scales and objective vestibular and balance examinations. Material and Methods A group of 131 patients (including 101 women; mean age: 59±14 years) of the audiology outpatient clinic was examined. Benign paroxysmal positional vertigo, phobic vertigo and central dizziness were the most common diseases observed in the study group. Patients’ symptoms were tested using the questionnaire on Cawthworne-Cooksey exercises (CC), Dizziness Handicap Inventory (DHI) and Duke Anxiety-Depression Scale. Berg Balance Scale (BBS), Dynamic Gait Index (DGI), the Tinetti test, Timed Up and Go test (TUG), and Dynamic Visual Acuity (DVA) were used for the functional balance assessment. Objective evaluation included: videonystagmography caloric test and static posturography. Results The study results revealed statistically significant but moderate compatibility between functional tests BBS, DGI, TUG, DVA and caloric results (Kendall’s W = 0.29) and higher for posturography (W = 0.33). The agreement between questionnaires and objective tests were very low (W = 0.08–0.11).The positive predictive values of BBS were 42% for caloric and 62% for posturography tests, of DGI – 46% and 57%, respectively. Conclusions The results of functional tests (BBS, DGI, TUG, DVA) revealed statistically significant correlations with objective balance tests but low predictive values did not allow to use these tests in vestibular damage screening. Only half of the patients with functional disturbances revealed abnormal caloric or posturography tests. The qualification to work based on objective tests ignore functional state of the worker, which may influence the ability to work. Med Pr 2018;69(2):179–189
Źródło:
Medycyna Pracy; 2018, 69, 2; 179-189
0465-5893
2353-1339
Pojawia się w:
Medycyna Pracy
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the rotor eccentricity on the torque of a cage induction machine
Autorzy:
Silwal, B.
Rasilo, P.
Belahcen, A.
Arkkio, A.
Powiązania:
https://bibliotekanauki.pl/articles/141083.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cage induction machine
dynamic eccentricity
electromagnetic torque
energy balance
finite element method
harmonics
Opis:
The non-uniform air gap in an electrical machine caused by rotor eccentricity creates an asymmetrical flux-density distribution in the air gap. This can affect the nominal torque produced by the machine. Eccentricity also produces forces that act on the rotor which may also have an effect on the torque. Thus, it is important to know how the torque of the machine behaves. In this paper, the torque of a cage induction machine is studied when the machine has dynamic eccentricity. The study is performed using the finite element method and a magnetic vector potential formulation. The torque is calculated by the method of energy balance. The harmonic components of the torque are also analyzed. The results show that the machine under eccentricity does not exhibit the same torque as a normal healthy machine. The harmonic components around the first principal slot harmonic is most affected.
Źródło:
Archives of Electrical Engineering; 2017, 66, 2; 383-396
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelowanie obciążalności prądowej przewodów napowietrznych linii elektroenergetycznych
Modeling ampacity of the conductors of the overhead power lines
Autorzy:
Kmak, J.
Nowak, W.
Szpyra, W.
Tarko, R.
Powiązania:
https://bibliotekanauki.pl/articles/268435.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Elektrotechniki i Automatyki
Tematy:
napowietrzne linie elektroenergetyczne
obciążalność dynamiczna linii
metoda elementów skończonych
dynamic thermal rating
heat balance equation
numerical model of conductor
Opis:
Wzrost zapotrzebowania na energię elektryczną wymusza konieczność modernizacji istniejących oraz budowanie nowych sieci elektroenergetycznych. Alternatywne rozwiązanie stanowi zastosowanie w istniejących sieciach systemów dynamicznej obciążalności. Dopuszczalny prąd jest w tych rozwiązaniach dostosowywany do panujących warunków zewnętrznych. Określenie obciążalności przewodu wymaga przeprowadzenia złożonych obliczeń z wykorzystaniem modeli matematycznych. W artykule przeanalizowano trzy przykładowe modele. Pierwszy oparty jest na bilansie cieplnym. Kolejne dwa modele wykorzystują obliczenia numeryczne w programie ANSYS i różnią się stopniem złożoności odwzorowania geometrii przewodu.
As a result of growth in demand for electricity changes in power systems are required. Modernization of existing power lines and building new ones is essential. The alternative is application of dynamic thermal rating systems. Permissible current in this case is adjusted to actual atmospheric conditions. For determining ampacity in this way complex calculations are required. Mathematical modeling is used. In framework of the article three different models are considered. The first one is based on heat balance equation. In others two variants numerical calculations in ANSYS are applied. The difference between them is in complexity of geometry models. The most satisfactory results are obtained for numerical calculations and accurate geometry of conductor.
Źródło:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej; 2017, 57; 47-50
1425-5766
2353-1290
Pojawia się w:
Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej
Dostawca treści:
Biblioteka Nauki
Artykuł
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