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EN
Fatigue and sleepiness are two major factors that have been reported to contribute to road crash and accidents in Indonesia. Fatigue among commercial drivers is probably a common phenomenon, particularly during long-duration driving. This study aimed at characterizing fatigue and sleepiness during long-duration driving. Nine commercial drivers were recruited in this field study and were requested to drive a multipurpose vehicle for three trips back and forth between two major cities. Each trip was completed within 4 hours, with about 3 to 3.5 hours of continuous driving (and 0.5 to 1 hour of rest). Fatigue was assessed by utilizing the Psychomotor Vigilance Task (PVT), which was administered for 5 minutes immediately following the completion of each trip. A video camera was employed to capture blink frequency, and for each trip, this measure was determined during 5 minutes after two hours of driving. Subjective ratings were also collected during the task and included the Swedish Occupational Fatigue Inventory (SOFI) and the Karolinska Sleepiness Scale (KSS). The results of this study demonstrated a consistent increase in the blink rate and subjective measures of fatigue. A significant association was also found between the blink rate and SOFI measures, indicating an association between those objective and subjective measures. Although not statistically significant, there were also changes in PVT parameters associated with driving duration. However, no significant association was found between PVT parameters and the subjective measures. This study found that a minimum of six hours of intermittent driving was adequate in inducing fatigue and sleepiness, despite the seemingly sufficient amount of rest break. Based on the findings of this study, it is suggested that long-duration driving be limited to a maximum of 12 hours, and that a minimum of 30 minutes of rest be provided after 3 to 4 hours of driving. This finding should be used as a basis for scheduling drivers and for finding the appropriate intervention strategy for mitigating fatigue and sleepiness risks during prolonged driving tasks.
2
Content available remote Fatigue risk management of the operator based on selected examples
EN
The article presents issues related to methods of risk management related to operator fatigue. An organization that wants to safely carry out operational tasks need effective methods and tools for risk assessment in safety system to increase the chances and likelihood of the organization achieving its goals. In this case, it is about identifying the risk of fatigue at work, controlling it and minimizing its negative effects. The article presents, on the example of a pilot, the possibilities of managing the risk of fatigue at work, both in the reactive, proactive and predictive dimensions, using selected examples of methods and tools. The summary emphasizes the need for a systemic risk management related to fatigue at work.
PL
W artykule przedstawiono zagadnienia związane z metodami zarządzania ryzykiem związanym ze zmęczeniem operatora. Organizacja, która chce bezpiecznie realizować zadania operacyjne potrzebuje efektywnych metod i narzędzi do szacowania ryzyka w systemie bezpieczeństwa, aby zwiększyć szanse oraz prawdopodobieństwo osiągnięcia przez organizację celów. W tym przypadku chodzi o rozpoznanie ryzyka związanego ze zmęczeniem w pracy, sterowanie nim i zminimalizowanie jego negatywnych skutków. W artykule przedstawiono, na przykładzie pilota, możliwości zarządzania ryzykiem jego zmęczenia w pracy, zarówno w wymiarze reaktywnym, proaktywnym, jak i predyktywnym, wykorzystując wybrane przykłady stosowanych metod i narzędzi. W podsumowaniu podkreślono konieczność podejścia systemowego do zarządzania ryzykiem związanym ze zmęczeniem.
EN
In the article, based on the research, the Tiredness Indicator was proposed. The research concerned the pilot's concentration and reaction time to individual stimuli. They were carried out using a flight simulator - CKAS MotionSim 5, located at the Poznan University of Technology. Measurements were made before and during the flight Analysis of the results showed a periodic course of tiredness characteristics, a marked increase in tiredness in the middle of tests and tiredness of only one sense organ confirmed by the results of reaction time and subjective assessment. Based on the conducted research, it can be stated that tiredness reduces the cognitive abilities of the human brain and extends the reaction time to stimuli.
PL
W artykule na podstawie przeprowadzonych badań zaproponowano wskaźnik zmęczenia. Badania dotyczyły koncentracji pilota i czasu reakcji na poszczególne bodźce. Przeprowadzono je za pomocą symulatora lotu - CKAS MotionSim 5, znajdującego się na Politechnice Poznańskiej. Pomiary wykonano przed i podczas lotu. Analiza wyników wykazała okresowy przebieg charakterystyk zmęczenia, wyraźny wzrost zmęczenia w połowie testów oraz zmęczenie tylko jednego narządu zmysłów, potwierdzone wynikami czasu reakcji i oceną subiektywną. Na podstawie przeprowadzonych badań można stwierdzić, że zmęczenie obniża zdolności poznawcze ludzkiego mózgu i wydłuża czas reakcji na bodźce.
EN
Presented work is primarily oriented on the experimental verification of the influence of fatigue on the psychological condition of the flying personnel, using psychological and performance tests. For the evaluation of a pilot performance, the 24 hours experiment was conducted. In total, eight subjects participated in the experimental measurements. Eight participants went through several tests, including simulator flights, to investigate the effects of the fatigue on the results of psychological measurements. Measurements included workload evaluation, using NASA task load evaluation concept and performance testing, using the so-called OR-test. Significant statistical differences between measurements performed during 24 hours were not found in the case of NASA task load Scores. In the case of OR-test, Friedman ANOVA and subsequent post-hoc analysis show that the greatest decrease in performance was observed in approximately 22 hours of wakefulness, i.e. approximately in half of the measuring process. The concept of 24-hour measurements for the quantification of fatigue is not commonly used yet as well as objectivization using performance testing. As the apparent effect of fatigue is mainly on performance testing results, it can be argued that this work could serve as a basis for further studies on fatigue. Also, it could serve as a support for introducing new pilots' psychological testing procedures in the future, which could contribute to current efforts to improve aviation safety.
EN
In recent years, the research of nodular cast iron has been focused on increasing fatigue resistence. In the paper, two types of alloyed nodular cast irons have been investigated – SiMo-nodular cast iron alloyed by 4% of silicon and 1% of molybdenum and SiCu-nodular cast iron alloyed by 4% of silicon and 1.5% of copper. SiMo-nodular cast iron is suitable for high-temperature applications, for example the exhaust manifolds of the combustion engines. SiCu-nodular cast iron is used in various components of tribotechnical units. These components are often loaded by fatigue. The mechanical and fatigue behaviour of both nodular cast iron types has been studied by means of tensile test, impact bending test, hardness test and fatigue tests. Fatigue tests were realised at low frequency cyclic push-pull loading up to 10 million cycles. The relationship between the amplitude of stress and number of cycles to failure was investigated and the fatigue strength was determined. Mechanical and fatigue properties of both nodular cast iron types are correlated with the microstructure of specimens.
6
Content available Fatigue life of butt weldments made of S1100QL steel
EN
Fields of application for quenched and tempered advanced high-strength steels are mainly ground-moving, mining equipment, commercial vehicles, and truck cranes. One of the main aspects determining range of applicability for the high strength steels is the possibility to obtain welded joints with the given fatigue strength. Information about fatigue behaviour of the weld joints strongly increases the operational safety of the structures. Factors influencing mechanical properties of the joints can be related to the welding parameters, i.e. welding current, voltage, and interpass and preheat temperatures. Thermo-mechanical process (fusion welding) also causes the diversification of the microstructure in the weld and heat affected zones. Microstructure changes induce residual stress, influencing the fatigue behaviour of the weld joint. The main topic of the paper are results of the experimental fatigue tests performed for S1100QL butt welds produced with two different technological parameter setups. Technological parameters configurations were selected on the basis of experimental tests carried out for sheets with a thickness of 12 mm. The low and high welding parameters differed due to energy introduced into the system. The energy was controlled by current parameters and the preheating of joined elements. In both configurations, it was possible to make welded joints that meet regulatory requirements but differ in the level of introduced internal stresses and microstructural properties in heat affected zone sizes. The joints were additionally subjected to standard strength and microstructural tests.
PL
Obszar zastosowania stali ulepszanych cieplnie to głównie maszyny służące do robót ziemnych, urządzenia górnicze, pojazdy użytkowe oraz żurawie samochodowe. Jednym z głównych aspektów określających zakres stosowalności stali wysoko wytrzymałych jest możliwość uzyskania połączeń spawanych o zadanej minimalnej wytrzymałości zmęczeniowej. Informacje na temat zjawisk zmęczeniowych zachodzących w złączach spawanych znacznie zwiększają bezpieczeństwo eksploatacyjne konstrukcji. Czynniki wpływające na właściwości mechaniczne złączy mogą być związane z parametrami spawania, tj. prądem spawania, napięciem, temperaturą międzyściegową i temperaturą wstępnego podgrzewania. Proces termomechaniczny, jakim jest spawanie łukiem elektrycznym, powoduje również zróżnicowanie mikrostruktury w samych spoinach i strefach wpływu ciepła. Zmiany mikrostruktury wywołują między innymi naprężenia szczątkowe wpływające na trwałość zmęczeniową złącza spawanego. Głównym tematem artykułu są wyniki eksperymentalnych testów zmęczeniowych wykonanych dla spoin doczołowych S1100QL wytworzonych przy użyciu dwóch różnych konfiguracji parametrów technologicznych. Połączenia zostały dodatkowo poddane standardowym testom wytrzymałościowym i mikrostrukturalnym. W artykule zaprezentowano również symulację propagacji wzrostu pęknięć zmęczeniowych.
PL
Omówiono zagrożenia kabli w użytkowanych mostach podwieszonych oraz przedstawiono konkluzje z prowadzonych w świecie badań nad metodami oceny stanu tych kabli i ze studiów nad racjonalnymi rozwiązaniami ich systemów. Poinformowano o wynikach międzynarodowej ankiety na temat systemów kabli mostów podwieszonych, problemów ich projektowania, kontroli i utrzymania przeprowadzonej przez Transportation Research Board (Washington) wśród administratorów mostów podwieszonych i specjalistów odpowiedzialnych za ich utrzymanie. Podano przykłady mostów z kablami podwieszającymi w złym stanie.
EN
Threats to cables in used cable-stayed bridges were discussed and conclusions were presented from world-wide research on methods for assessing the condition of these cables and from studies on rational solutions of their systems. The results of an international questionnaire on stay-cable bridges problems of their design, control and maintenance, carried out by the Transportation Research Board (Washington) among the administrators of stay-cable bridges and specialists responsible for their maintenance were announced. Examples of bridges with stay cables in poor condition are given.
PL
W artykule zaproponowano zintegrowane środowisko graficzne do zestawiania metod przetwarzania sygnału EKG celem separacji załamków R. Współczesne systemy automatyzacji i informatyzacji pola walki zaczynają dotyczyć nie tylko środków bojowych ale również załóg i obsług wysoce specjalistycznego oprzyrządowania. W artykule opisano efektywność algorytmów przetwarzania sygnału EKG, na potrzeby elektronicznych urządzeń medycznych i biomedycznych, w których zaawansowane sensory i algorytmy mają nieprzerwanie monitorować wydolność i gotowość do prowadzenia działań bojowych przez żołnierzy. Autor opisuje efektywności dobieranych doświadczalnie algorytmów oraz ograniczenia i wyzwania w procesowaniu sygnałów EKG, w odniesieniu do stosowanych metod.
EN
The article proposes an integrated graphical environment for the compilation of ECG signal processing methods for the separation of R-waves. Modern automation systems and computerization of the battlefield begin to deal not only with combat assets but also crews and the handling of highly specialized instrumentation. The article describes the efficiency of the ECG signal processing algorithms, for the needs of electronic medical and biomedical devices, in which advanced sensors and algorithms are to continually monitor the efficiency and readiness to conduct combat operations by soldiers. The author describes the effectiveness of experimentally selected algorithms as well as limitations and challenges in ECG signal processing in relation to applied methods.
EN
The article presents an analysis of the change in air voids in asphalt mixtures subjected to fatigue tests at three temperatures of 0°C, 10°C and 25°C. The X-ray computerized tomography imaging method, XCT, was used to identify the air voids in the samples. The research allowed to determine changes in the content of air voids in subsequent fatigue cycles in the sample area. The relationship between air voids volume and the stiffness modulus value was also determined during fatigue for three temperatures. The largest changes were found in samples with notches at 0°C. The analysis of the change in the content of air voids showed that the micro-cracking nucleation processes develop with the number of fatigue cycles. Using the numerical model finite element method we determined the distribution and change in fatigue damage in the extreme areas of the sample during various stages of fatigue. We found clear relationship between the damage and the increased content of air voids.
PL
Współczesne badania wskazują na brak pozytywnego wpływu na zdrowie dużych obciążeń fizycznych w pracy zawodowej, zwłaszcza w połączeniu z deficytem aktywności fizycznej rekreacyjnej w czasie wolnym od pracy. Kobiety, ze względu na uwarunkowania fizjologiczne, nie są w stanie wykonywać wszystkich czynności w pracy na równi z mężczyznami. Dotyczy to zwłaszcza prac związanych z wysiłkiem fizycznym i transportem ciężarów oraz wymuszoną pozycją ciała. W przypadku kobiet starszych, oprócz fizjologicznych różnic podyktowanych płcią, dochodzą zmiany funkcjonalne zachodzące w organizmie ludzkim wraz z wiekiem, które również istotnie obniżają możliwość wykonywania pracy fizycznej. Lekceważenie przez pracodawców problemu ciężkiej pracy fizycznej prowadzi do niekorzystnych skutków, zarówno dla pracowników, jak i dla firmy. Nadmierne obciążenie i związane z nim zmęczenie pracownika jest przyczyną gorszej jakości i wydajności pracy oraz zwiększenia absencji chorobowej. Dlatego oczywista wydaje się konieczność dostosowywania stanowisk i warunków pracy do potrzeb pracownic fizycznych w starszym wieku.
EN
Contemporary studies indicate the lack of a positive impact of high physical effort in professional work on health, especially in connection with the deficit of recreational physical activity during leisure time. Women, due to physiological conditions, are not able to perform all activities at work equally with men. This applies in particular to work related to physical effort, transport of weights and forced body position. In the case of older women, apart from the physiological differences dictated by gender, functional changes occurring in the ageing human body, which also significantly reduce the ability to perform physical work, are added. The problem of employers disregarding hard physical labour leads to adverse effects for both them and their companies. Excessive work toad and, associated with it, fatigue of employees result in inferior quality and work efficiency and the increase in sick leave due to ailments and illnesses. Therefore, it seems obvious to adapt the work station and working conditions to the needs of older women that perform physical work.
EN
The traditional overhead conductors (OHL conductors) are made from a high strength steel core and several layers of aluminium wires. Operating conditions under variable stress derived from von Karman vortices leads to fatigue cracking of the outer layer of wires, first of the outer layer, and then the inner layers. The dynamic component of tension, dependent on the static tension of the wire, its geometric construction and rigidity (the number and diameter of the wires, the coil angle), lead to fatigue destruction of the wires. The conse-quence of this is the gradual degradation of the conductor as a whole, which is a decrease in the electrically active cross-section, and as a result of overheating, also in its mechanical properties. The ultimate effect is breaking of the conductor and a fault of the power line. The subject of the paper concerns fatigue strength tests of cold-drawn commercially pure aluminium wires in different temper of strain hardening. The paper attempts to describe fatigue strength, research methodology, description of a research stand. Based on study results and their analysis, conclusions were formulated concerning the differentiation of fatigue strength and EN AW-1370 wires used for overhead power conductors.
EN
Aluminum alloys are widely used for fabrication of aircraft, civil structures, and space vehicles. Fatigue life consideration of a material is the most important design criteria in many such critical applications. In this research work, a widely used Aluminum alloy AA2219-T87 was TIG welded using AA2319 as a filler material. The effect of natural aging on Fatigue Crack Propagation Rate (FCPR) of welded and non-welded compact tension (CT) specimens (AA2219˗T87) is studied. The relationship between stress intensity factor (ΔK) and crack ratio (a/W) for different value of the crack length in base metal and the welded zone is presented. Paris curves for both welded and non-welded specimens and compared to study the effect of natural aging (NA) on FCGR and compared with non-aged specimens. The results obtained provide a base for the development of Structural Health Monitoring systems for the propagation of crack growth in such components.
EN
Numerical analysis of deflection for the existing solution of the friction lift carrying ropes suspension was presented in this article. A similar analysis for the optimized bracket of the carrying ropes suspension was demonstrated from the geometrical point of view. Finite Element Method was used for calculations. It allows mapping the actual operating conditions by using commercial SolidWorks software. Geometrical modifications of the bracket were proposed to save time of manufacturing the detail parts. On that basis, the calculations of percentage indicator of the construction damage and its durability were performed in both cases .
EN
This study aimed to explore the effect of fatigue on the biomechanical contribution of the lower extremity joints during a typical stretch-shortening cycle (SSC) task. Methods: 15 male athletes completed drop jump (DJ) under pre- and post-fatigue. Vicon motion capture system and 3D Kistler force plates were used to collect kinematics and ground reaction force data simultaneously. Results: Under fatigue condition, 1) the DJ height decreased; the touchdown angle of knee and ankle reduced and the range of motion increased; 2) the maximum push-off moment and power of knee was reduced; 3) the stiffness of knee, ankle, and legs was reduced; 4) the energy generation and the net energy of the ankle decreased; 5) the energy contribution of knee decreased during the eccentric phase. Conclusions: Fatigue altered biomechanical contribution of the lower extremity joints by changing the movement pattern during DJ. The control ability of the knee and ankle were decreased. Eventually, the jump performance was reduced. In addition, the decrease of stiffness as well as the energy contribution of these joints can be used as sensitive indices to evaluate the performance of DJ after fatigue.
EN
The aim of the study was to find out whether among young active people – the future healthcare professionals – there is a risk of developing lumbar spine overload disease depending on the occurrence of the disbalance of paravertebral muscles and to assess the fatigue of the examined muscles depending on the body position during the work. Methods: The study involved 50 randomly selected students of physiotherapy and emergency medical services of a mean age of 21 years. The surface electromyography (sEMG) was used to measure the activity level of spinal extensors of the cervical and lumbar spine. The statistical analysis of the results was made using the RStudio software. Results: Study shows that the majority of the examined students had a slight asymmetry between the bioelectric activity of the right- and left-side dorsal extensor bands, both in the cervical and lumbar sections (right side 118.6 Hz / left side 115.7 Hz / extension and 98.6 Hz / 95.5 Hz /flexion). Depending on the position, significant fatigue in the examined muscles was found ( p < 0.05). Conclusions: The experiment showed a slight disbalance in the average bioelectromyographic activity in the area of spinal extensors during their symmetrical work. This can be the basis for the development of the overload disease in the weaker muscle parts, which generate more fatigue during the activity. It is worth to carry out similar tests in a much greater group, taking the longer-lasting muscular effort into account.
PL
Sektor służby zdrowia charakteryzuje się zmiennością modeli czasu pracy, ustawicznie długimi godzinami pracy związanymi z korzystaniem z indywidualnego „prawa wyboru” (klauzula opt-out) oraz brakiem rozwiązania w kwestii dyżurowania European Trade Union Confederation (ETUC). W artykule przedstawiono wyniki badań przeprowadzonych w różnych krajach, które przybliżają problemy wynikające z niewłaściwej organizacji czasu pracy, głównie pracujących w szpitalach lekarzy rezydentów i starają się wyjaśnić przyczyny tych problemów. Wskazują one na potrzebę i kierunki zmian, które zapewniłyby obywatelom jako potencjalnym pacjentom, wyższy poziom jakości usług medycznych.
EN
The health services sector is characterized by the volatile working-time models, chronic long working hours linked to the use of the individual “opt-out” and lack of solution in terms of on-call time of European Trade Union Confederation (ETUC). This article presents the results of the studies conducted in various countries, which present problems resulting from the improper organization of working time. The issue mainly refers to the resident doctors working in the hospitals, and tries to explain the causes of these problems. The results of the research point both to the need for and the direction for changes that would ensure higher quality of medical services for citizens as potential patients.
PL
W pracy zaprezentowano wyniki badań trwałościowych końcówki drążka kierowniczego pojazdu o dmc powyżej 3.5 tony. W badaniach wykorzystywano wielkogabarytową platformę wibroizolowaną, serwohydrauliczny siłownik mobilny oraz cyfrowy kontroler sygnałów IST Instron. Próby prowadzono w warunkach działania obciążenia zmiennego cyklicznie do uzyskania 2×106 cykli. Ze względu na kompleksową ocenę zachowania końcówki drążka kierowniczego testy przerywano, by wykonywać oględziny obiektu badań. Wyznaczono zmiany kąta wychylenia oraz momentu siły w funkcji liczby cykli oraz przedstawiono ich prognozę. Omówiono procedurę badawczą służącą ocenie trwałości przegubu kulistego.
EN
The paper reports results from test of steering rod tip used in car having permissible total mass above 3.5 t. Anti-vibration platform, servo-hydraulic actuator and digital controller IST Instron were used to execute the tests. The experiments were carried out under cyclic loading up to 2×106 cycles. The tests were interrupted for inspecting the examined object. Variations of angle and force moment and prediction of their values versus number of cycles are presented. Details of experimental procedure for evaluation of steering rod tip are provided.
PL
W pracy porównano własności statyczne oraz zmęczeniowe materiałów platerowanych przed oraz po obróbce cieplnej. We wszystkich przypadkach zastosowano jednakowy materiał podstawowy – stal niestopową P355NH, zaś materiałami nakładanymi były stale austenityczne: 254SMO, 316L, stopy niklu: C-276, Alloy 625 oraz super-duplex SAF2507. W ramach pracy przeprowadzono obróbkę cieplną w temperaturze 910°C, a następnie wykonano badania statyczne (próba zginania, ścinania, rozciągania), badanie udarności, rozkładu twardości w przekroju próbki oraz badania na cykliczne zginanie.
EN
This paper describe the comparison of static and fatigue properties of clad materials before and after heat treatment. In all cases was used the same base material - P355NH carbon steel and the clad materials was: 254SMO and 316L austenitic steels, C-276 and alloy 625 nickel alloys, as well as SAF2507 super-duplex. As part of the work, heat treatment was carried out at 910°C and then static tests (bend test, shear test, tensile test) impact test, hardness distribution tests in the specimen cross-section and cyclic bending were performed.
PL
W pracy opisano strukturę, właściwości mechaniczne oraz rozwój pęknięć zmęczeniowych w układach platerów cyrkon-stal zgrzewanych wybuchowo, poddanych długotrwałemu oddziaływaniu temperatury. Próbki w stanie po spojeniu wygrzewano w temperaturze 600°C w czasie 10 i 100 godzin, a następnie poddano obserwacjom mikroskopowym, określono twardość, wytrzymałość na rozciąganie oraz poddano wahadłowemu zginaniu. W odkształconych próbkach zaobserwowano wzrost pęknięć zmęczeniowych równolegle do przyłożonego obciążenia, przy czym inicjacja pęknięć występowała w stali.
EN
The paper describes the structure, mechanical properties and fatigue cracks growth in explosively welded zirconium - carbon steel cladding system subjected to long-lasting temperature impact. After annealing at 600°C for 10 and 100 hours the samples were subjected to microscopic observations and finally the microhardness, tensile strength and cyclic bending were determined. In the deformed specimens the initiation of fatigue cracks occurred in the steel whereas further cracks growth occurred parallel to the applied load.
20
PL
W pracy zaprezentowano wyniki badań zmęczeniowych łącznika spawalniczego stal-aluminium z międzywarstwą tytanu Grade 1. Badany materiał został poddany analizie mikrostrukturalnej. Przeanalizowano czynniki wpływające na trwałość zmęczeniową oraz zaprezentowano podstawową analizę pęknięć zmęczeniowych zaobserwowanych podczas badań.
EN
The paper presents the results of fatigue tests of a steel-aluminum welding transition joint with titanium Grade 1 interlayer. Metallic composite was subjected to microstructural analysis. Factors influencing fatigue durability were analyzed and the basic analysis of fatigue cracks observed during tests was presented.
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