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Tytuł:
Experimental and numerical investigations on dynamic tensile behavior of a ZrB2-SiC ceramic
Autorzy:
He, R.
Cao, J.
Yang, K.
Wang, L.
Kong, D.
Powiązania:
https://bibliotekanauki.pl/articles/38695710.pdf
Data publikacji:
2023
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
ZrB2-SiC ceramic
dynamic tensile properties
fracture pattern
strain rate
peridynamic model
Opis:
The dynamic tensile behavior of a ZrB2-SiC ceramic was investigated via split Hopkinson pressure bar tests and a bond-based peridynamic model. The experimental results showed that the peak dynamic splitting tensile stress increased linearly with the strain rate. The dynamic tensile stress history and fracture pattern exhibited a significant strain-rate dependence. In simulation, the strain-rate dependent on the critical energy release rate was introduced to predict the dynamic tensile behavior of the ZrB2-SiC ceramic. The numerical results were in good agreement with the experimental results, verifying the applicability of the peridynamic model. The maximum error of the peak dynamic splitting tensile stress between the experimental and numerical results was no greater than 6%. Moreover, the effect of the strain rate on the fracture patterns of the ZrB2-SiC ceramic composite can be well predicted by the peridynamics method. The ZrB2-SiC composite specimen split into two large fragments with additional small fragments under dynamic splitting tension. With the increase of strain rate, the main crack propagation and branching led to a larger fracture region in the middle of the specimen.
Źródło:
Archives of Mechanics; 2023, 75, 1-2; 53-73
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The endemic radiodonts of the Cambrian Stage 4 Guanshan Biota of South China
Autorzy:
Jiao, D.-G.
Pates, S.
Lerosey-Aubril, R.
Ortega-Hernandez, J.
Yang, J.
Lan, T.
Zhang, X-G.
Powiązania:
https://bibliotekanauki.pl/articles/2082327.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Amplectobeluidae
Anomalocarididae
Tamisiocarididae
Paranomalocaris
Burgess Shale-type exceptional
preservation
shallow water
Cambrian
China
Opis:
The Guanshan Biota (South China, Cambrian, Stage 4) contains a diverse assemblage of biomineralizing and non-biomineralizing animals. Sitting temporally between the Stage 3 Chengjiang and Wuliuan Kaili Biotas, the Guanshan Biota contains numerous fossil organisms that are exclusive to this exceptional deposit. The Guanshan Konservat-Lagerstätte is also unusual amongst Cambrian strata that preserve non-biomineralized material, as it was deposited in a relatively shallow water setting. In this contribution we double the diversity of radiodonts known from the Guanshan Biota from two to four, and describe the second species of Paranomalocaris. In addition, we report the first tamisiocaridid from South China, and confirm the presence of a tetraradial oral cone bearing small and large plates in “Anomalocaris” kunmingensis, the most abundant radiodont from the deposit. All four radiodont species, and three genera, are apparently endemic to the Guanshan Biota. When considered in the wider context of geographically and temporally comparable radiodont faunas, endemism in Guanshan radiodonts is most likely a consequence of the shallower and more proximal environment in which they lived. The strong coupling of free-swimming radiodonts and benthic communities underlines the complex relationship between the palaeobiogeographic and environmental distributions of prey and predators. This local adaptation of radiodonts to their prey is highlighted by the frontal appendage morphology of the two species of Paranomalocaris, apparently specialised to different feeding modes, while the recognition of the limited geographic range of some radiodont faunas highlights the importance of exploring as many deposits as possible to fully understand this group.
Źródło:
Acta Palaeontologica Polonica; 2021, 66, 2; 255-274
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reconstruction of oviraptorid clutches illuminates their unique nesting biology
Autorzy:
Yang, T.-R.
Wiemann, J.
Xu, L.
Cheng, Y.-N.
Wu, X.-C.
Sander, P.M.
Powiązania:
https://bibliotekanauki.pl/articles/19933.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
Oviraptorosaurs, a group of non-avian theropod dinosaurs from the Cretaceous of Asia and North America, left behind the most abundant and informative fossil evidence of dinosaur reproductive biology. Previous studies had suggested that oviraptorosaur reproductive biology represents an intermediate stage and exhibited unique modern avian traits. For instance, the adult-associated clutches were predominantly considered as evidence for brooding/thermoregulatory contact incubation (TCI) behaviors, whereas the hypotheses of laying or protection were neglected. Despite numerous oviraptorid egg clutches uncovered from China and Mongolia, their nest architecture and clutch arrangement were rarely investigated in detail. Here we present a comprehensive reconstruction of an oviraptorid clutch based on five new oviraptorid clutches from Jiangxi Province, China. A detailed examination of the new clutches reveals a partially-open oviraptorid nest that contains 3–4 rings of paired eggs (more than 15 pairs total) whose blunt end points toward the center devoid of eggs at an angle of 35–40°. Our detailed three-dimensional reconstruction indicates that the oviraptorid clutch has a unique architecture unknown from extant bird clutches, implying an apomorphic nesting mode. Such a unique nest architecture further contradicts the TCI hypothesis in oviraptorids, hindering sufficient heat transfer to the inner (lower) ring(s) of eggs. Moreover, the size of the new oviraptorid clutches (>30 eggs) is significantly larger than that of the adult-associated clutches (<22 eggs), raising the alternative hypothesis that the adult-associated clutches were uncompleted. This clue thus supports the hypothesis that the clutch-associated oviraptorid adults possibly represent females after an oviposition before a catastrophic sandstorm/flooding burial.
Źródło:
Acta Palaeontologica Polonica; 2019, 64, 3
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, Characterization and Compatibility Studies of Poly(DFAMO/NIMMO) with Propellant and PBX Ingredients
Autorzy:
Li, H.
Yang, Y.
Pan, J.
Wang, W.
Pan, R.
Zhu, W.
Powiązania:
https://bibliotekanauki.pl/articles/358094.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
energetic binder
synthesis
characterization
compatibility
PDN
Opis:
Oxetane-based polymers substituted with difluoroamino groups can be used as energetic binders in propellants and polymer-bonded explosives (PBXs). As a novel candidate, poly(3-difluoroaminomethyl-3-methyloxetane/3-nitratomethyl-3-methyloxetane) (PDN) was synthesized and its structure was established. Thermogravimetry (TG) and differential scanning calorimetry (DSC) were employed to investigate its thermal decomposition behaviour. The compatibility between PDN and some common ingredients of propellants and PBXs was evaluated by the DSC method. PDN with good thermal stability was synthesized via a cationic solution polymerization process. Additionally, it has improved compatibility with cyclotetramethylenetetranitramine (HMX), carbon black (C.B.) and lead carbonate (PbCO3) compared with homopoly(3-difluoroaminomethyl-3-methyloxetane) (PDFAMO). PDN could be used as a promising difluoroamino energetic binder in the future.
Źródło:
Central European Journal of Energetic Materials; 2018, 15, 1; 85-99
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compressive optical image encryption using phase-shifting interferometry on a joint transform correlator
Autorzy:
Li, J.
Jia, B.
Dai, X.
Lei, M.
Yang, C.
Li, H.
Li, R.
Powiązania:
https://bibliotekanauki.pl/articles/174905.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fully optical system
holographic interferometry
joint transform correlator (JTC)
binary scrambling method
inverse problems
Opis:
A compressive optical image encryption method, which combines compressive sensing with phase-shifting interferometry on a joint transform correlator, is proposed in the fully optical domain. The object image is first permutated using a binary scrambling method. Next, the permutated object field is encrypted and registered as the holograms by phase-shifting interferometry on the joint transform correlator setup. Then, the encrypted images and the key are compressed to the compressed data using single-pixel compressive imaging. The original image can be reconstructed and decrypted using the specified algorithm. The simulations demonstrate that the method is effective and suitable for image security transmission.
Źródło:
Optica Applicata; 2017, 47, 2; 245-256
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Eddy current density asymmetric distribution of damper bars in bulb tubular turbine generator
Autorzy:
Qiu, H.
Fan, X.
Yi, R.
Feng, J.
Wu, J.
YANG, C.
ZHAO, H.
Powiązania:
https://bibliotekanauki.pl/articles/140467.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
damper bars
bulb tubular turbine generator
electromagnetic field
eddy current
Opis:
The major reasons that cause the damage of damper bars in the leeward side are found in this paper. It provides a route for the structure optimization design of a hydro generator. Firstly, capacity of a 24 MW bulb tubular turbine generator is taken as an example in this paper. The transient electromagnetic field model is established, and the correctness of the model is verified by the comparison of experimental results and simulation data. Secondly, when the generator is operated at rated condition, the eddy current density distributions of damper bars are studied. And the asymmetric phenomenon of the eddy current density on damper bars is discovered. The change laws of the eddy currents in damper bars are determined through further analysis. Thirdly, through the study of eddy current distributions under different conditions, it is confirmed that the stator slots and armature reaction are the main factors to affect the asymmetric distribution of the eddy current in damper bars. Finally, the studies of the magnetic density distribution and theoretical analysis revealed the asymmetric distribution mechanism of eddy current density.
Źródło:
Archives of Electrical Engineering; 2017, 66, 3; 571-581
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Efficiency Covering Technology for Covered Yarns Production: Equipment and Experimente
Wysokowydajna technologia przędzenia z owijaniem
Autorzy:
Feng, P.
Zhang, R.
Gan, J.
Yang, C.
Powiązania:
https://bibliotekanauki.pl/articles/233138.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
high efficiency
covering technology
covered yarn
rotation speed
low cost
proces teksturowania
przędza poliamidowa
przędzenie z owijaniem
cechy strukturalne przędzy
Opis:
A new covering technology for producing covered yarns is proposed in this article. On a traditional yarn covering machine, a hollow spindle rotates with a bobbin of the outer wrapping yarn. In the new equipment, the turntable rotates with only one single outer wrapping yarn. With a magnetic device, the bobbin of core yarns is suspended in a balloon formed by outer wrapping yarns. The rotation speed of the turntable can reach 40000 rpm. A series of experiments on the new equipment were conducted and some covered yarn samples were obtained. The performance of these samples were tested and compared with that produced by traditional machines.
W artykule zaproponowano nową technologię przędzenia z owijaniem. W eksperymentach zastosowano 5 prędkości obrotowych: 12.000, 20.000, 27.000, 32.000 and 35.000 r.p.m. Przy użyciu mikroskopu porównano otrzymane przędze z przędzami otrzymanymi metodą tradycyjną. Stwierdzono, że tradycyjna przędza była bardziej puszysta, a przędza otrzymana nową metodą charakteryzowała się dobrą równomiernością. Po porównaniu dwóch rodzajów przędz stwierdzono, że równomierność skrętu przędzy uzyskanej nową metodą jest wyższa, ponieważ w nowym sposobie przędzenia zastosowano synchroniczny napęd taśmy, co skutkuje mniejszymi wahaniami prędkości obrotowej.
Źródło:
Fibres & Textiles in Eastern Europe; 2017, 3 (123); 73-78
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Chest Injury Mechanism Caused by Different Seatbelt Loads in Frontal Impact
Autorzy:
Xiao, S.
Yang, J.
Crandall, J. R.
Powiązania:
https://bibliotekanauki.pl/articles/306880.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
model ciała człowieka
FEM
kinematyka
klatka piersiowa
seatbelt restraint system
human body finite element model
kinematics
rib fractures
chest deflections
Opis:
The purpose of this quantitative study is to investigate the differences of the injury mechanism caused by two different types of seatbelts loads on the occupant chest. Methods: The finite element analysis is employed to compare the different responses of the human body model, including the comparison of kinematics, chest accelerations, seatbelt forces and chest injury outcomes regrading chest deflections and rib fractures. Results: The calculated rib strain/stress from simulations in force-limiting seatbelt are higher than that in the regular seatbelt. The forward movement and torso twist are both great in simulations with force-limiting seatbelt. Meanwhile, there are obvious differences in the injury outcomes of chest deflections and rib fracture risks under the different seatbelt loads. Conclusion: Results indicate the chest deflections and rib fracture risks are negatively correlated under the load of the force-limiting seatbelt, However, they are positively correlated to and determined by the seatbelt peak load of the regular seatbelt. This paper can provide a reference for study of the chest injury mechanism and the protection efficiency of seatbelt.
Źródło:
Acta of Bioengineering and Biomechanics; 2017, 19, 3; 53-62
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal aging of hydrogenated nitrile rubber – loss of additives and its influence on elasticity maintenance
Starzenie termiczne uwodornionego kauczuku nitrylowego – ubytek dodatków i jego wpływ na zachowanie elastyczności
Autorzy:
Liu, X.
Zhao, J.
Yang, R.
Iervolino, R.
Barbera, S.
Powiązania:
https://bibliotekanauki.pl/articles/945800.pdf
Data publikacji:
2017
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
hydrogenated nitrile rubber
thermal aging
additives
elasticity
uwodorniony kauczuk nitrylowy
starzenie termiczne
dodatki
elastyczność
Opis:
The thermal aging of hydrogenated nitrile rubber (HNBR) at elevated temperatures 125 and 150 °C was investigated. The changes of chemical structures, including functional groups and crosslinking density, and the changes of mechanical properties, including recovery from bending (RFB), tensile strength, elongation at break and Young's modulus, were determined. In addition, the loss of additives was analyzed by pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The aging procedure of HNBR exhibited two stages: loss of additives along with the deterioration of elasticity; obvious oxidation and extra crosslinking with further hardening and embrittlement. The relationship between the deterioration of elasticity and the loss of plasticizers was established. It was demonstrated that the failure of HNBR happened long before obvious oxidation and crosslinking of the rubber chains, and the loss of additives, especially the loss of plasticizers, was the main reason for the failure. Therefore, the elasticity recovery of aged HNBR immersed in the plasticizer (n-propyl palmitate as a model) was carried out. This treatment was demonstrated to be effective before obvious oxidation and crosslinking of HNBR occurred during the thermal aging.
Badano starzenie termiczne uwodornionego kauczuku nitrylowego (HNBR) w temperaturze 125 i 150 °C. Określono zmiany struktur chemicznych, w tym grup funkcyjnych i gęstości usieciowania oraz zmiany właściwości mechanicznych, w tym powrotu poodkształceniowego po zginaniu (RFB), wytrzymałości na rozciąganie, wydłużenia przy zerwaniu i modułu Younga. Ponadto metodą pirolitycznej chromatografii gazowej z detekcją mas (Py-GC/MS) analizowano straty dodatków obecnych w kauczuku. Procedura starzenia się HNBR wykazywała dwa etapy: ubytek dodatków wraz z pogorszeniem elastyczności; wyraźne utlenianie i dodatkowe sieciowanie związane z dalszym utwardzaniem i zwiększaniem kruchości. Określono zależność pomiędzy zmniejszaniem się elastyczności a ubytkiem dodatków zmiękczających. Wykazano, że pogorszenie właściwości HNBR następowało znacznie wcześniej niż utlenianie i sieciowanie oraz było spowodowane utratą dodatków, a zwłaszcza plastyfikatorów. W związku z tym przeprowadzono próbę odtworzenia elastyczności starzonych próbek HNBR przez zanurzenie w plastyfikatorze (palmitynian n-propylu jako model). Obróbka ta okazała się skuteczna, pod warunkiem przeprowadzenia jej zanim podczas starzenia termicznego nastąpiło utlenianie i sieciowanie HNBR.
Źródło:
Polimery; 2017, 62, 7-8; 588-598
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Soft-sediment deformation structures in cores from lacustrine slurry deposits of the Late Triassic Yanchang Fm. (central China)
Autorzy:
Yang, R.
van Loon, A. J.
Yin, W.
Fan, A.
Han, Z.
Powiązania:
https://bibliotekanauki.pl/articles/94445.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
soft-sediment deformation structures
low-density gravity-flow deposits
Triassic
lacustrine sediments
Ordos basin
China
struktury deformacji
osady miękkie
złoża grawitacyjne o niskiej gęstości
trias
osady jeziorne
zlewnia
Ordos
Chiny
Opis:
The fine-grained autochthonous sedimentation in the deep part of a Late Triassic lake was frequently interrupted by gravity-induced mass flows. Some of these mass flows were so rich in water that they must have represented slurries. This can be deduced from the soft-sediment deformation structures that abound in cores from these lacustrine deposits which constitute the Yanchang Fm., which is present in the Ordos Basin (central China). The flows and the resulting SSDS were probably triggered by earthquakes, volcanic eruptions, shear stress of gravity flows, and/or the sudden release of overburden-induced excess pore-fluid pressure. The tectonically active setting, the depositional slope and the high sedimentation rate facilitated the development of soft-sediment deformations, which consist mainly of load casts and associated structures such as pseudonodules and flame structures. Sediments with such deformations were occasionally eroded by slurries and became embedded in their deposits.
Źródło:
Geologos; 2016, 22, 3; 201-211
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability analysis and H∞ control of discrete T–S fuzzy hyperbolic systems
Autorzy:
Duan, R.
Li, J.
Zhang, Y.
Yang, Y.
Chen, G.
Powiązania:
https://bibliotekanauki.pl/articles/331173.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
discrete T–S fuzzy hyperbolic model
parallel distributed compensation
positive diagonally dominant matrices
robust stability
model Takagi-Sugeno
kompensacja rozproszona
sterowanie odporne
Opis:
This paper focuses on the problem of constraint control for a class of discrete-time nonlinear systems. Firstly, a new discrete T–S fuzzy hyperbolic model is proposed to represent a class of discrete-time nonlinear systems. By means of the parallel distributed compensation (PDC) method, a novel asymptotic stabilizing control law with the “soft” constraint property is designed. The main advantage is that the proposed control method may achieve a small control amplitude. Secondly, for an uncertain discrete T–S fuzzy hyperbolic system with external disturbances, by the proposed control method, the robust stability and H∞ performance are developed by using a Lyapunov function, and some sufficient conditions are established through seeking feasible solutions of some linear matrix inequalities (LMIs) to obtain several positive diagonally dominant (PDD) matrices. Finally, the validity and feasibility of the proposed schemes are demonstrated by a numerical example and a Van de Vusse one, and some comparisons of the discrete T–S fuzzy hyperbolic model with the discrete T–S fuzzy linear one are also given to illustrate the advantage of our approach.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2016, 26, 1; 133-145
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Feature extraction of molten pool for laser welding quality real-time inspection
Autorzy:
Zhang, J
Yin, H
Huang, H
Yang, R
Yang, J
Li, Y
Powiązania:
https://bibliotekanauki.pl/articles/173597.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
laser materials processing
process monitoring and control
image analysis
Opis:
This paper proposed an image feature extraction method for laser welding molten pool inspection based on cellular neural network. TC4 titanium alloy thin plates were welded by Nd:YAG pulsed laser. A coaxial machine vision system was designed to acquire molten pool images. An auxiliary lighting source was employed to improve the molten pool image quality. By analyzing molten pool images, the welding defects such as fenestration or insufficient depth were identified. These results can be used as a feedback signal for laser power control. Experimental results showed that the proposed method can be used to improve laser welding quality.
Źródło:
Optica Applicata; 2015, 45, 4; 523-533
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inspection optimization model with imperfect maintenance based on a three-stage failure process
Model optymalizacji przeglądów w warunkach niepełnej konserwacji oparty o trójfazowy proces uszkodzenia
Autorzy:
Yang, R.
Zhao, F.
Kang, J.
Li, H.
Teng, H.
Powiązania:
https://bibliotekanauki.pl/articles/1365969.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
delay time modeling
three-stage failure process
inspection
imperfect maintenance
proportional age reduction
Modelowanie metodą czasu zwłoki
trójfazowy proces uszkodzenia
przegląd
konserwacja niepełna
proporcjonalne obniżenie wieku
Opis:
Rolling element bearings are one of the most widely used and vulnerable components in complex systems. The condition monitoring work is very critical for sustaining the system’s availability and reducing the maintenance cost. Shock pulse method (SPM) is a common technique to measure the operating condition of rolling bearings as a three color scheme, e.g., green, yellow and red. This paper proposes an inspection model based on a three-stage failure process which aims to optimize the inspection interval of bearings by minimizing the expected cost per unit time. The three-stage failure process divides the bearings life into three stages before failure: good, minor defective and severe defective stages, corresponding to the three color scheme of SPM. Considering the need to lubricate bearings when the minor defective stage is identified by inspection in industrial applications, we assume that maintenance at the time of inspection identifying the minor defective stage is imperfect. The concept of proportional age reduction is used to model the effect of imperfect maintenance on the instantaneous rates of the minor defective stage, the severe defective stage and failure. Perfect maintenance however is carried out if inspection detects bearings being in the severe defective stage. Failure can be found once it occurs and replacement has to be implemented immediately. Finally, a numerical example is presented to illustrate the effectiveness of the proposed model.
Łożyska toczne są jednymi z najczęściej stosowanych i jednocześnie najbardziej narażonych na uszkodzenia części składowych układów złożonych. Monitorowanie stanu odgrywa bardzo istotną rolę w utrzymaniu dostępności układów i zmniejszeniu kosztów ich obsługi. Metoda impulsów uderzeniowych (SPM) jest powszechnie stosowaną techniką służącą do pomiaru stanu pracy łożysk tocznych, który reprezentowany jest za pomocą kodu trzech kolorów, na przykład, zielonego, żółtego i czerwonego. W artykule zaproponowano model przeglądów oparty na trójfazowym procesie uszkodzenia, który ma na celu optymalizację częstotliwości przeglądów łożysk poprzez minimalizację oczekiwanych kosztów przypadających na jednostkę czasu. Pojęcie trójfazowego procesu uszkodzenia pozwala podzielić żywotność łożyska na trzy fazy przed wystąpieniem uszkodzenia: fazę dobrego stanu, fazę drobnych defektów i fazę poważnych defektów. Podział ten odpowiada kodowi trzech kolorów SPM. Biorąc pod uwagę konieczność smarowania łożysk po zdiagnozowaniu, podczas przeglądu w warunkach przemysłowych, wystąpienia fazy drobnych defektów, zakładamy, że konserwacja w czasie takiego przeglądu jest konserwacją niepełną. Koncepcja proporcjonalnego obniżenia wieku służy do modelowania wpływu niepełnej konserwacji na chwilowe wartości intensywności fazy drobnych defektów, fazy poważnych defektów oraz uszkodzeń. Gdy podczas przeglądu stwierdzi się, że łożysko jest w fazie poważnych defektów, przeprowadza się pełną konserwację. Uszkodzenie zostaje wykryte zaraz po jego wystąpieniu, i wtedy należy dokonać natychmiastowej wymiany łożyska. Pod koniec artykułu, przedstawiono przykład numeryczny, który ilustruje wydajność proponowanego modelu.
Źródło:
Eksploatacja i Niezawodność; 2015, 17, 2; 165-173
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Non-isothermal Decomposition Kinetics of 1-Amino-1,2,3-triazolium Nitrate
Autorzy:
Du, X.-J.
Zou, M.-S.
Li, X.-D.
Yang, R.-J.
Powiązania:
https://bibliotekanauki.pl/articles/358020.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
1-amino-1,2,3-triazolium nitrate
thermal decomposition
TG
non-isothermal kinetics
compensating effect
Opis:
The thermal decomposition kinetics of 1-amino-1,2,3-triazolium nitrate (ATZ-NO3) was investigated by non-isothermal TG-DTG at various heating rates (2, 5, 10, 15, and 20 °C∙min-1). The results showed that the thermal decomposition of ATZ-NO3 consists of two mass-loss stages. The first mass-loss stage corresponds to the loss of nitrate anion and the substituent group, while the second stage corresponds to the splitting of the triazole ring. The kinetic triplets of the two stages were described by a three-step method. Firstly, the Kissinger and Ozawa methods were used to calculate the apparent activation energies (E) and pre-exponential factors (A) of the two decomposition stages. Secondly, two calculation methods (the Šatava-Šesták and Achar methods) were used to obtain several probable decomposition mechanism functions. Thirdly, three assessment methods (the Šatava, double-extrapolation, and the Popescu methods) were used to confirm the most probable decomposition mechanism functions. The reaction models for both stages are random-into-nuclear and random-growth mechanisms, with n = 3/2 for the first stage and n = 1/3, m = 3 for the second stage. The kinetic equations for the two decomposition stages of ATZ-NO3 may be expressed as [wzór]. Mathematical expressions for the kinetic compensation effect were derived.
Źródło:
Central European Journal of Energetic Materials; 2014, 11, 1; 99-114
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dispersion-compensating en/decoder for a time-spreading/wavelength-hopping optical code-division multiplexing (OCDM) system
Autorzy:
Zheng, J.
Wang, R.
Pu, T.
Lu, L.
Fang, T.
Su, Y.
Li, L.
Yang, Q.
Chen, X.
Powiązania:
https://bibliotekanauki.pl/articles/174365.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
optical code-division multiplexing (OCDM)
fiber Bragg grating (FBG)
dispersion
Opis:
A novel dispersion-compensating fiber Bragg grating (FBG)-based en/decoder is proposed to compensate both the out-band and in-band dispersion in a time-spreading/wavelength-hopping (TS/WH) optical code-division multiplexing (OCDM) system. The experimental realization of such en/decoders only needs a uniform-pitch phase mask and a sub-micrometer precision moving stage. Such an en/decoder pair with the ability of compensating the dispersion of transmission in 20-km single mode fiber (SMF) is simulated and experimentally fabricated. Both the simulation and experimental results show that the decoded pulse can be recovered without any distortion owing to the elimination of dispersion.
Źródło:
Optica Applicata; 2013, 43, 3; 485-495
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
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