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Tytuł:
Effects of unstable elements with different hardness on lower limb loading
Autorzy:
Li, F.
Mei, Q.
Gu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/307265.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ciśnienie podeszwowe
stopa
staw kolanowy
twardość
knee adduction moment
plantar pressure
unstable elements
hardness
foot
Opis:
Purpose: Osteoarthritis of the knee is one of the most common diseases. For this chronic disease, modified footwear structure can effectively prevent and relieve disease of the knee. The aim of this study was to explore the effects of shoe surface elastic modulus on external knee adduction moment and ground reaction force and foot loading characteristics. Methods: Sixteen healthy female volunteers were recruited, and each subject performed five walking trials under two shoes condition. The lower limb loading data was collected using force platform and in-sole pressure measurement system. Results: The results showed that the external knee adduction moment was decreased in all stance phase when wearing SS (unstable shoes with soft unstable elements), compared with HS (unstable shoes with hard unstable elements). The ground reaction force showed no obvious change under two shoes condition. Additionally, compared with HS, plantar pressure transferred from medial foot to lateral foot when wearing SS. Along with changes of contact areas, average pressure and impulse had also presented this tendency. Conclusions: These results can provide some scientific evidence and suggestions for footwear companies, and for the foot plantar medial injury disease has also certain applicability.
Źródło:
Acta of Bioengineering and Biomechanics; 2015, 17, 2; 85-92
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Looped-chain-based active current sharing strategy in DC microgrids
Autorzy:
Li, D.
Liu, Y.
Gu, Y.
Qi, H.
Powiązania:
https://bibliotekanauki.pl/articles/141109.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
active current sharing
DC microgrids
looped control diagram
Opis:
The integration of renewable energy sources in modern electric grids have drawn increasing attention nowadays. In order to effectively manage large-scale renewable energy sources and achieve flexible and efficient operation, the concept of microgrids have been proposed. Considering the nature of DC outputs in many distributed energy resources (DERs), DC microgrids have been extensively studied in the past years. Among the operational issues in DC microgrids, current sharing issues have become an important topic since it is highly relevant to the operation of DC microgrids. By adopting a proper design of current sharing strategy in DC microgrids, the current rating violations in each interface converter can be successfully avoided. In this paper, a looped-chainbased active current sharing strategy is proposed to realize high accuracy current sharing in DC microgrids. In particular, the output current is shared between the neighboring interface converters. Hence, following a clockwise or counter-clockwise order, a loopedchain- based control diagram can be established to share the reference value of the output current. A final status in the whole DC microgrid is that the output current of every interface converter is equalized. Hence, the desired current sharing objective can be satisfied. A MATLAB simulation model is established to verify the proposed loopedchain- based active current sharing strategy in DC microgrids.
Źródło:
Archives of Electrical Engineering; 2017, 66, 3; 559-569
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigating biomechanical function of toes through external manipulation integrating analysis
Autorzy:
Mei, Q.
Fernandes, J.
Hume, P.
Gu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/306943.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
palec nogi
uchwyt
przyczepność
uszkodzenia
toes
grip
windlass mechanism
metatarsal injury
Opis:
Purpose: This study was aimed to investigate the function of toes while running through comparing bound toes by external-manipulation with natural separate toes by evaluating kinematics and plantar pressure analysis. Methods: Seven habitually barefoot male runners participated in the running test under toes binding and non-binding conditions, and Vicon and Novel insole plantar pressure measurement were conducted synchronously to collect kinematics and foot loading. Results: Ankle kinematics showed larger non-significant range of motion in the frontal plane while running with toes non-binding.The medial forefoot had a smaller force time integral, and with hallux had a larger force time integral than those of running with toes binding, with significance level p < 0.05. Conclusions: While no significance existed between bound and non-bound toes in kinematics, the medial forefoot had a smaller foot impulse and the hallux had a larger foot impulse for those with non-binding feet. This suggests that other functions such as the active gripping action of toes might be important for the efficiency of the foot windlass mechanism (the plantar fascia support), which would be beneficial for running performance improvement and foot injury prevention.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 1; 97-102
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
How foot morphology changes influence shoe comfort and plantar pressure before and after long distance running?
Autorzy:
Mey, Q.
Gu, Y.
Sun, D.
Fernandez, J.
Powiązania:
https://bibliotekanauki.pl/articles/306388.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ciśnienie podeszwowe
obuwie
kształt stopy
komfort
bieg długodynstansowy
foot shape
plantar pressure
footwear
comfort
long distance running
Opis:
Prolonged running has been popularized globally in recent decades. This study was aimed to reveal information about foot morphology, shoe comfort and plantar loading among recreational heel-strike runners. Methods: Twenty-six runners participated in foot morphology, perceived scores and peak pressure tests after 10- and 20-km track running. The foot morphology was measured using a 3D foot scanner, perceived scores were recorded using a visual analogue scale and plantar pressure was measured via insole plantar pressure measurement system. The statistical significance level was set at 0.05. Results: The heel midsole materials properties were measured before and after 20 km. Significant changes were observed in ball width and girth, arch height and foot volume. The perceived scores showed significance in overall, forefoot and heel comfort, arch support and forefoot width. Peak pressure to the heel, medial mid-foot and metatarsal greatly increased. The first metatarsal showed consecutive increase from static to 10 km, and 20 km, while big-toe showed a decrease. Conclusions: The morphology variations and forefoot loading concentration may lead to discomfort and possibly imply dermatological problems and metatarsal bone stress, particularly on the first metatarsal. Combining changes of heel midsole property, knowledge of foot shape, shoe perception and plantar pressure is of great value for recreational long-distance running shoes design and materials selection.
Źródło:
Acta of Bioengineering and Biomechanics; 2018, 20, 2; 179-186
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on Fluorescence Characteristic of a Complex Probe οf CdSe Quantum Dots Coupling with Thiazole Orange
Autorzy:
Fei, X.
Jia, G.
Wang, J.
Gu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/1537765.pdf
Data publikacji:
2010-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.63.Kv
78.55.-m
78.67.-n
Opis:
CdSe quantum dots were synthesized using thioglycolic acid as stabilizer in aqueous solution under $N_{2}$. The UV-vis spectrometry and fluorescence spectra indicate that the bimodal quantum dots were formed and the optical band gaps are about 650 nm and 750 nm, respectively. The quantum dots coated with TO were prepared in room temperature, and the fluorescence characteristic was studied. The result showed that the peak shift of quantum dots fluorescence spectra can mainly be due to the change of the capping layer, resulting in the confinement energy change. This is vital for the investigating on of the forming process and mechanisms of the combination of thiazole orange dye and quantum dots.
Źródło:
Acta Physica Polonica A; 2010, 117, 6; 949-952
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of performance level on lower limb kinematics during table tennis forehand loop
Autorzy:
Qian, J.
Zhang, Y.
Baker, J. S.
Gu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/307434.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
strefa graniczna
łańcuch kinematyczny
sport
lower limb drive
contact area
stretch-shortening cycle
kinetic chain
Opis:
Understanding of biomechanics is important in performance development since each skill has a fundamental mechanical structure. The purpose of this study was to investigate differences in lower limb kinematics during table tennis forehand loop between superior players (SP) and intermediate players (IP). Thirteen male players as superior and thirteen as intermediate participated in this test. A VICON motion analysis system and a Novel Pedar insole plantar pressure measurement system were used to record kinematic and contact area data, respectively. Participants were asked to execute single forehand loop against topspin ball with maximal power. Key findings were that SP showed significantly larger hip flexion and knee external rotation at backward-end and larger hip internal rotation and extension at forward-end compared with IP. Contact areas at both events were larger for SP. In addition, SP showed significantly larger joints angular changing rate during forward swing at the ankle and hip. Results indicated that SP possessed better ability of using lower limb drive in forehand loop.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 3; 149-155
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Female mouse model of diabetes mellitus induced by streptozotocin and high-carbohydrate high-fat diet
Autorzy:
Guo, R.
Dong, J.
Wang, D.Q.
Gu, Y.F.
Powiązania:
https://bibliotekanauki.pl/articles/16627528.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
diabetes mellitus
female mouse
pathological analysis
streptozotocin
high-carbohydrate high-fat diet
Opis:
With the improvement of people’s living standards and rapid economic development, the incidence of diabetes mellitus (DM) is increasing in most parts of the world. DM presents an important potential threat to human health. In the present study, a model of diabetes in female mice was established, and fasting blood glucose was detected at week 4, after which the biochemical profiles were evaluated by histopathological analysis. The success rate of modeling in the normal control (NC) group and the low/ middle/high-dose streptozotocin (STZ) group were 0, 0, 25% and 60%, respectively. In the middle-dose and high-dose STZ groups, the liver index was increased significantly compared with the NC group (p<0.05). The blood biochemical indicators of total cholesterol and low density lipoprotein cholesterol in three STZ injection groups were as follows: alanine aminotransferase and aspartate transaminase in middle- and high-dose STZ groups, high-density lipoprotein cholesterol and serum creatinine in the high-dose STZ group, and blood urea nitrogen in the middle-dose STZ group were significantly increased (p<0.05). The level of total triglycerides was lower, obviously, in the high-dose STZ group than in the NC group (p<0.05). The mice showed marked steatosis, green-dyed fiber tissue coloring in varying degrees, and the contour of the hepatic lobules basically disappeared in STZ injection groups. The results suggest that to establish a diabetes model for female ICR mice, the optimum dose of STZ is 100 mg/kg.
Źródło:
Polish Journal of Veterinary Sciences; 2022, 25, 4; 547-555
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Review of the Photodecomposition of Some Important Energetic Materials
Autorzy:
Sun, Y.
Shu, Y.
Xu, T.
Shui, M.
Zhao, Z.
Gu, Y.
Wang, X.
Powiązania:
https://bibliotekanauki.pl/articles/358397.pdf
Data publikacji:
2012
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
photodecomposition mechanisms
energetic materials
Opis:
The photodecomposition mechanisms of energetic materials vary with molecular structure, photodissociation wavelength, the phase of the material, experimental pressure and temperature etc. In this paper, the significant progress on photodecomposition studies of some important energetic materials achieved in recent years is introduced in detail, including nitromethane, DMNA (dimethylnitramine), TATB (1,3,5-triamino-2,4,6-trinitrobenzene), RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), HMX (1,3,5,7-tetranitro-1,3,5,7- tetrazacycloctane) and CL-20 (2,4,6,8,10,12-hexanitrohexaazaisowurtzitane). The difficulties and prospects of photodecomposition research of energetic materials are also indicated.
Źródło:
Central European Journal of Energetic Materials; 2012, 9, 4; 411-423
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Superconducting Wind Turbine Generators
Autorzy:
Pan, Y.
Gu, D.
Powiązania:
https://bibliotekanauki.pl/articles/136186.pdf
Data publikacji:
2016
Wydawca:
EEEIC International Barbara Leonowicz Szabłowska
Tematy:
superconducting
wind turbines
torque
types
Opis:
Wind energy is well known as a renewable energy because its clean and less polluted characteristic, which is the foundation of development modern wind electricity. To find more efficient wind turbine is the focus of scientists around the world. Compared from conventional wind turbines, superconducting wind turbine generators have advantages at zero resistance, smaller size and lighter weight. Superconducting wind turbine will inevitably become the main trends in this area. This paper intends to introduce the basic concept and principle of superconductivity, and compare form traditional wind turbine to obtain superiority, then to summary three proposed machine concept.While superconductivity have difficulty in modern technology and we also have proposed some challenges in achieving superconducting wind turbine finally.
Źródło:
Transactions on Environment and Electrical Engineering; 2016, 1, 3; 9-15
2450-5730
Pojawia się w:
Transactions on Environment and Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selective flotation of siderite and quartz from a carbonate-containing refractory iron ore using a novel amino-acid-based collector
Autorzy:
Gu, X.
Zhu, Y.
Li, Y.
Han, Y.
Powiązania:
https://bibliotekanauki.pl/articles/110222.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
flotation
quartz
hematite
siderite
refractory iron ores
molecular simulation
Opis:
A novel and highly-efficient amino-acid-based collector, α-ethylenediamine lauric acid (α-EDA-LA), was studied to selectively beneficiate carbonate-containing refractory hematite ores. Single mineral and synthetic mixture flotation tests were carried out to investigate its floating performance. Zeta potential, fourier transform infrared spectroscopy (FTIR) and Density Functional Theory-based molecular simulation were used to identify the adsorption mechanism. The flotation results showed that quartz could be collected effectively at pH 11.0-12.0 in the reverse flotation. For siderite, the recovery peaked at 83.4% at pH 8.0, where siderite presented different floatability from magnetite and hematite. Exploiting such difference, the separation of siderite could be achieved. Zeta-potential measurements showed that α-EDA-LA adsorption on the surfaces of siderite and quartz decreased the corresponding zeta potentials at pH of 8.0-10.0 and 8.0-12.0, respectively. This means the adsorption overcome the electrostatic repulsion between α-EDA-LA and the mineral surfaces. The molecular simulation indicated that no chemisorption took place between α-EDA-LA and quartz. FTIR analysis suggested that α-EDA-LA was adsorbed on quartz via hydrogen bonding. The adsorption of α-EDA-LA on siderite surface was dominated by chemisorption, while further enhanced by hydrogen bonding. This study filled the gap in the research on siderite flotation reagents and its adsorption mechanism.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 803-813
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stress-strain response of sheared wheat granular material stored in silos using triaxial compression tests
Autorzy:
Zeng, C.
Gu, H.
Wang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/2082870.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
wheat granular
void ratio
confining pressure
shearing velocity
strength
dilatancy
Opis:
Wheat granular material stored in silos usually suffers shearing loads, which induces complex stress-strain response during the silo filling and discharging process. In order to guarantee the safe storage of these granular materials, it is necessary to investigate the shearing behaviour of wheat granular material in silos. In this paper, a series of triaxial tests were conducted on wheat granular material by using a modified double cell triaxial system. The stress-strain responses including the volumetric strain behaviour were examined considering the effect of the initial void ratio, confining pressure and shearing velocity. Different shearing states were discussed to obtain their strength parameters in various conditions. The results show that the shearing characteristics of wheat granular material are influenced by the shearing velocity. The friction angles increase with the decreasing void ratio at different states. The final volumetric strain decreases with increasing confining pressure, and the dilation is diminished. The dilatancy behaviour was quantitatively evaluated based on Row’s theory for wheat granular material. The stress-strain relationship of wheat granular material was then determined.
Źródło:
International Agrophysics; 2020, 34, 1; 103-114
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flotation behavior and separation mechanism of quartz and iron minerals in α-bromolauric acid reverse flotation system
Autorzy:
Han, Y.
Guo, W.
Zhu, Y.
Wei, Y.
Gu, X.
Powiązania:
https://bibliotekanauki.pl/articles/949733.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
quartz
separation
reverse flotation
iron minerals
α-Bromolauric acid
Opis:
A new type collector α-Bromolauric acid (α-BLA) had been proved to be an efficient collector for quartz flotation. However, the effects of α-BLA on the flotation behavior of iron minerals and quartz-iron separation had not been investigated. In this study, collector α-BLA was synthesized in the laboratory. The flotation behavior of quartz, hematite and magnetite under α-BLA reverse flotation system were investigated and the separation mechanism of quartz-irons was studied by contact angle, zeta-potential and infrared spectroscopy. The results showed that the optimum flotation pH was 11.5 for quartz, 6.45 for hematite and 6.97 for magnetite. The best α-BLA concentrations was 75 mg/dm3 for quartz flotation, 125 mg/dm3 for hematite and magnetite flotation. The activator CaCl2 had little effect on the flotation of hematite and magnetite, but the minimum dosage 50 mg/dm3 of activator CaCl2 was necessary for quartz flotation. On the contrary, starch had no effect on the flotation of quartz, while the recoveries of magnetite and hematite tended to be 0% as starch concentration more than 80 mg/dm3. The separation mechanism of quartz from iron minerals under α-BLA reverse flotation system was that the starch could be selectively adsorbed on the surface of hematite and magnetite in the form of strong hydrogen bond adsorption. However, the same adsorption of starch did not occur on the surface of quartz, so the α-BLA can be successfully adsorbed on the surface of activated quartz to make the quartz strongly hydrophobic, and then to be floated out.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 992-1003
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A method to analyze the machining accuracy reliability sensitivity of machine tools based on Fast Markov Chain simulation
Podejście do analizy czułości niezawodnościowej dokładności obrabiarek oparte na symulacji metodą szybkich łańcuchów Markowa
Autorzy:
Cheng, Q.
Sun, B.
Zhao, Y.
Gu, P.
Powiązania:
https://bibliotekanauki.pl/articles/301814.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
machining accuracy reliability
machine tool
fast Markov Chain
reliability sensitivity analysis
integral of failure probability
niezawodność dokładności obróbki
obrabiarka
szybki łańcuch Markowa
analiza czułości niezawodnościowej
całka prawdopodobieństwa uszkodzenia
Opis:
With the ever increasing demand of higher machining accuracies, the machining accuracy reliability has evolved into an indicator to evaluate the performance of a machine tool. Consequentially, methods for improving the machining accuracy reliability have become the focus of attention for both manufacturers and users. Generally, the intercoupling geometric errors are the main cause which may lead to a reduction of the machining accuracy of machine tools. In this paper, the machining accuracy reliability is defined as the ability of a machine tool to perform at its specified machining accuracy under the stated conditions for a given period of time, and a new approach for analyzing the machining accuracy reliability of machine tools based on fast Markov chain simulations is proposed. Using this method, seven different failure modes could be determined for a machine tool. An analysis of the machining accuracy reliability sensitivity was performed based on solving the integral of the failure probability of the machine tool, and the key geometric errors which most strongly affect the machining accuracy reliability were identified. Finally, in this study, a 4-axis machine tool was selected as an example to experimentally validate the effectiveness of the proposed method.
Wraz z wciąż rosnącym zapotrzebowaniem na coraz to wyższą dokładność obróbki, niezawodność dokładności obróbki stała się wskaźnikiem pozwalającym na ocenę charakterystyk obrabiarek. W rezultacie, metody doskonalenia niezawodności dokładności obróbki znalazły się w centrum uwagi zarówno producentów jak i użytkowników tych maszyn. Na ogół, do zmniejszenia dokładności obróbki prowadzą nakładające się błędy geometryczne. W niniejszej pracy, niezawodność dokładności obróbki zdefiniowano jako zdolność obrabiarki do pracy z określoną dla niej dokładnością w zadanych warunkach przez dany okres czasu. Zaproponowano nowe podejście do analizy niezawodności dokładności obróbki oparte na symulacji metodą szybkich łańcuchów Markowa. Za pomocą tej metody, można ustalić siedem różnych przyczyn uszkodzeń obrabiarki. Analizę czułości niezawodnościowej dokładności obróbki przeprowadzono obliczając całkę prawdopodobieństwa uszkodzenia obrabiarki. Określono także kluczowe błędy geometryczne, które najsilniej wpływają na niezawodność dokładności obróbki. Wreszcie, efektywność proponowanej metody sprawdzono doświadczalnie na przykładzie obrabiarki czteroosiowej.
Źródło:
Eksploatacja i Niezawodność; 2016, 18, 4; 552-564
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A generalized equivalent temperature model in a time-varying environment
Uogólniony model temperatury równoważnej w zmiennym w czasie otoczeniu
Autorzy:
Sun, L.
Gu, X.-H.
Song, P.
Di, Y.
Powiązania:
https://bibliotekanauki.pl/articles/301556.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
przyspieszone badania starzenia
temperatura równoważna
przechowywanie w warunkach naturalnych
krzywa degradacji
oringi nitrylowe
accelerated degradation test
equivalent temperature
nature storage
degradation path
rubber Orings
Opis:
Accelerated degradation test at high temperature level is a common method to accelerate the degradation of products by elevating temperature, and the obtained degradation data are then used to obtain the estimate of the performance at normal temperature after extrapolating the degradation through accelerating model. However, the normal temperature is ever-changing rather than constant. Therefore, a generalized equivalent temperature model based on power law degradation path is proposed to establish a connection between accelerated degradation data and degradation data at normal temperature. The model takes the equal degradation measure as a principle and the conclusion is demonstrated that the increments of the degradation under the same magnitude, same time and different orders of temperature stresses are same. The result shows that the empirical equivalent temperature model is a special case of the proposed model. The accuracy of the proposed model is finally demonstrated by a case study of nitrile rubber O-rings.
Przyspieszone badania degradacji (badania starzeniowe) prowadzone w warunkach wysokiej temperatury stanowią powszechnie stosowaną metodę przyspieszania starzenia produktów poprzez podwyższanie temperatury. Otrzymane w takich badaniach dane degradacyjne wykorzystuje się do szacowania wydajności produktu w temperaturze normalnej na zasadzie ekstrapolacji. Głównym ograniczeniem tej metody jest fakt, że normalna temperatura nie jest stała lecz zmienia się w czasie. Dlatego też, aby skorelować dane z przyspieszonej degradacji z danymi dotyczącymi starzenia w normalnej temperaturze, zaproponowaliśmy uogólniony model temperatury równoważnej oparty na krzywej degradacji opisanej prawem potęgowym. W modelu przyjęto zasadę równego stopnia degradacji i wykazano, że przyrosty degradacji przy tej samej wartości i czasie działania naprężeń termicznych różnego rzędu są takie same. Wyniki pokazują, że empiryczny model temperatury równoważnej jest szczególnym przypadkiem proponowanego przez nas modelu. Trafność opisanego w pracy modelu wykazano na podstawie studium przypadku dotyczącego uszczelek nitrylowych, tzw. oringów.
Źródło:
Eksploatacja i Niezawodność; 2017, 19, 3; 432-440
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Features of distribution of uranium and thorium in red mud
Autorzy:
Gu, H.
Wang, N.
Yang, Y.
Zhao, C.
Cui, S.
Powiązania:
https://bibliotekanauki.pl/articles/110444.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
red mud
uranium
thorium
distribution
perovskite
Opis:
Natural radioactive elements such as uranium and thorium restrict the use of red mud as building materials or additives, and may cause environmental problems. The distribution features of U and Th in red mud was studied from micro and macro analysis, using EPMA, LA-ICP-MS, and methods of mineralogy and beneficiation. Based on the micro-area scanning analysis, main chemical compositions in red mud, such as Ca, Al, Si, Na, and K are dispersive while Fe and Ti mainly tend to concentrate in granular phases. Based on the in-situ analysis, the distribution of main elements and most trace elements in micro-zone of red mud was homogeneous. In micro-zone area, the variation tendency of thorium content was similar with Y in red mud samples. By means of the methods of mineralogy and beneficiation, red mud samples were separated into different fractions. U and Th tend to be enriched in the low density fraction of the red mud. Th presented a high concentration in the finest particle size fractions of the red mud. Neither U or Th was regularly distributed in various magnetic red mud fractions. Thorium fingerprint peaks were determined in perovskite by EDX under TEM, which is proposed to be one of the radioactivity sources in Bayer red mud.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 1; 110-120
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 19

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