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Tytuł:
Effects of Welding Heat Input on Microstructure and Corrosion Characterization in CGHAZ of X80 Pipeline Steel
Autorzy:
Wang, Xue-Mei
Zhao, Wei
Chen, Kai
Li, Zhen
Powiązania:
https://bibliotekanauki.pl/articles/28099607.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
X80 pipeline steel
coarse grain heat-affected zone
heat input
corrosion
Opis:
The coarse-grained heat-affected zone specimens of X80 pipeline steel were produced by welding thermal simulation under different heat inputs of 10, 30, and 55 kJ/cm to study the effects of heat input on microstructure evolution and corrosion characterization. The corrosion resistance of coarse-grained heat-affected zones was poorer than that of base metal due to less homogenous in the former. For 10 kJ/cm coarse-grained heat-affected zone, the corrosion resistance was poorer than the others due to the more adsorption hydrogen around the needle-like martensite/austenite constituents and greater galvanic driving force between the needle-like martensite/austenite constituents and ferrite. In carbonate/bicarbonate solution, better corrosion resistance for coarse-grained heat-affected zones was obtained when the heat input is 30 kJ/cm, which can be attributed to the severe coarse martensite/austenite constituents for 55 kJ/cm coarse-grained heat-affected zone. In the H2S environment, the better corrosion resistance for coarse-grained heat-affected zone was obtained when the heat input is 55 kJ/cm, which can be attributed to the protective effect of corrosion products. In addition, the high content of M/A constituents for 30 kJ/cm CGHAZ was good for hydrogen adsorption, which was adverse to the corrosion resistance in acid environments.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 2; 659--671
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineral investment risk assessment of host countries based on a cloud matter-element model
Ocena ryzyka inwestycji w minerały w krajach przyjmujących w oparciu o model chmury materii i pierwiastka
Autorzy:
Hou, Jie
Li, Guoqing
Ling, Jiahong
Chen, Lianyun
Zhao, Wei
Sheng, Baoli
Powiązania:
https://bibliotekanauki.pl/articles/27311628.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
mineral investment
cloud matter element model
investment risk
risk assessment
inwestycje w surowce mineralne
model materii chmury
ryzyko inwestycyjne
ocena ryzyka
Źródło:
Gospodarka Surowcami Mineralnymi; 2023, 39, 4; 23--48
0860-0953
Pojawia się w:
Gospodarka Surowcami Mineralnymi
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic emission characteristics of deep granite under triaxial cylic loading and unloading
Autorzy:
Pei, Feng
Zhang, Yue-Zheng
Zhao, Ji-Wei
Geng, Jing-Ming
Powiązania:
https://bibliotekanauki.pl/articles/1402362.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
Tematy:
deep granite
acoustic emission
frequency spectrum
precursory feature recognition
Opis:
In order to obtain the damage and AE characteristics of deep granite, TAW-2000 electrohydraulic servo rigid testing equipment and PCI-2 acoustic emission acquisition system were used to clarify the relationship between AE characteristics and stress level under conventional triaxial and cyclic loading and unloading. The results show that: AE characteristic parameters such as counts and energy under different confining pressures have good consistency in reflecting cracks growth process, which correspond to the stress level of rock sample; Before the critical failure, the AE amplitude increases significantly and extremely high peak frequency and extremely low peak frequency began to appear; The phenomenon that peak frequency band number increases significantly can be used as the precursor of rock failure; The change trend of characteristic parameters, amplitude and peak frequency band were related to the stress level of rock, and the loading path has little influence on it, which verified the effectiveness of AE precursory feature recognition; FR value decreases continuously with the increase of cyclic stress level and overall trend is downward, which indicated that AE memory gradually decreases as the stress level increases; From the perspective of damage mechanics, the AE characteristics of rock before failure are explained reasonably by the development of damage rate.
Źródło:
Mining Science; 2020, 27; 209-225
2300-9586
2353-5423
Pojawia się w:
Mining Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PISA Science Score: A Good Indicator of Competence in S & T?
Autorzy:
Shi, Wei-Zhao
Powiązania:
https://bibliotekanauki.pl/articles/26469703.pdf
Data publikacji:
2013-03-31
Wydawca:
Wydawnictwo Adam Marszałek
Tematy:
PISA
science education
indicator
competence in science and technology
Opis:
In this study, the data from the Programme for International Student Assessment (PISA) are used to investigate whether the PISA science test score is a good indicator of competence in science and technology. The researcher uses a number of scientific and technical journal articles per million people as a measure instrument to represent the competence of science and technology. A regression model analysis suggests that the PISA science scores would significantly predict competence in S & T, even when controlling the number of researchers in R&D per million people and the R&D expenditure (% of GDP). Moreover, it shows that R&D expenditure (% of GDP) is another important determinant of the competence in S & T. Multicollinearity is also found between the R&D expenditure (% of GDP) and the number of researchers in R&D per million people. The policy implication is clear.
Źródło:
The New Educational Review; 2013, 31; 51-59
1732-6729
Pojawia się w:
The New Educational Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An approach to multiple attribute decision making with combined weight information in interval-valued intuitionistic fuzzy environment
Autorzy:
Wei, G.
Zhao, X.
Powiązania:
https://bibliotekanauki.pl/articles/206267.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
multiple attribute decision making
interval-valued intuitionistic fuzzy number
interval-valued intuitionistic fuzzy weighted averaging (IIFWA)
weight information
Opis:
With respect to multiple attribute decision making problems with interval-valued intuitionistic fuzzy information, some operational laws of interval-valued intuitionistic fuzzy numbers, score function and accuracy function of interval-valued intuitionistic fuzzy numbers are introduced. A combined optimization model based on the deviation method, by which the attribute weights can be determined, is established. For special situations, in which information about attribute weights is completely unknown, we establish another combined optimization model. By solving this model, we get a simple and exact formula, which can be used to determine the attribute weights. We utilize the interval-valued intuitionistic fuzzy weighted averaging (IIFWA) operator to aggregate the intuitionistic fuzzy information corresponding to each alternative, and then rank the alternatives and select the most desirable one(s) according to the score and accuracy functions. Finally, an illustrative example is given to verify the developed approach and to demonstrate its practicality and effectiveness.
Źródło:
Control and Cybernetics; 2012, 41, 1; 97-112
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prefabricated fractured rock under stepwise loading and unloading
Autorzy:
Zhang, Wei
Zhao, Tongbin
Yin, Yanchun
Powiązania:
https://bibliotekanauki.pl/articles/2086954.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
fractured rock
graded loading and unloading
rock deformation
energy evolution
acoustic emission
Opis:
After the engineering rock mass has been affected by comprehensive effects of mining and disturbance, it experiences an input of external energy as well as dissipation and release of internal energy. From the viewpoint of energy, characteristics of rock failure are studied, and the law of rock unstable deformation and energy evolution is analyzed. The damage mechanism of rock is revealed easily. A gradual loading and unloading test of fractured rock is carried out to analyze deformation characteristics of the fractured rock during the load- -bearing process, and to study the law of energy dissipation and release under different load- ing and unloading stress levels. The results show that: (1) the load-bearing time, loading and unloading stress level, stress at crack initiation and peak stress of fractured rock gradually decrease with an increase in the number of cracks, and the descending speed decreases grad- ually with the increase in the number of cracks; (2) the strain at crack initiation and peak strain of the fractured rock increase gradually with an increase in the number of cracks, and the gathering speed decreases with the increase of the number of cracks; (3) the released strain energy and dissipation energy of fractured rock increase with an increase of loading and unloading stress levels, and the increasing rate gradually slows down; (4) the number of acoustic emission events is positively related to the degree of rock damage, and the increase in the number of cracks will prolong duration of the number of acoustic emission events. The results have a theoretical value for energy evolution and deformation damage of fractured rock masses, and also provide experimental experience to study the instability precursor information of rock materials from the viewpoint of energy.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 1; 167--179
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A source discrimination method of mine water-inrush based on 3D spatial interpolation of rare classes
Analiza dyskryminacyjna źródeł wycieków wody do kopalni na podstawie trójwymiarowej interpolacji danych o zdarzeniach rzadkich
Autorzy:
Jiang, Qiong
Zhao, Weidong
Zheng, Yong
Wei, Jiajia
Wei, Chao
Powiązania:
https://bibliotekanauki.pl/articles/219790.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
analiza dyskryminacyjna źródeł wycieków
wyciek wód
jakość wód
kryterium Bayesowskie
kategoria zdarzeń rzadkich
source discrimination
water inrush
water quality
Bayesian classifier
rare class
Opis:
When the distribution of water quality samples is roughly balanced, the Bayesian criterion model of water-inrush source generally can obtain relatively accurate results of water-inrush source identification. However, it is often difficult to achieve desired classification results when training samples are imbalanced. Sample imbalance is common in the source identification of mine water-inrush. Therefore, we propose a three-dimensional (3D) spatial resampling method based on rare water quality samples, which achieves the balance of water quality samples. Based on the virtual water sample points distributed by the 3D grid, the method uses the 3D Inverse Distance Weighting (IDW) method to interpolate the groundwater ion concentration of the virtual water samples to achieve oversampling of rare water samples. Case study in Gubei Coal Mine shows that the method improves overall discriminant accuracy of the Bayesian criterion model by 5.26%, from 85.26% to 90.69%. In particular, the discriminative precision of the rare class is improved from 0% to 83.33%, which indicates that the method can improve the discriminant accuracy of the rare class to large extent. In addition, this method increases the Kappa coefficient of the model by 19.92%, from 52.26% to 72.19%, increasing the degree of consistency from “general” to “significant”. Our research is of significance to enriching and improving the theory of prevention and treatment of mine water damage.
W przypadku zrównoważonych danych o jakościowym rozkładzie próbek, zastosowanie kryterium Bayesowskiego do modelowania źródeł wycieków daje stosunkowo dokładne wyniki w analizie dyskryminacyjnej źródeł wycieków wody kopalnianej. Jednakże w przypadku niezrównoważonych danych, pożądane efekty kategoryzacji są niezmiernie trudne do uzyskania. Dane o składzie próbek są w znacznej mierze niezrównoważone, i jest to powszechny problem napotykany przy identyfikacji źródeł wycieków. W obecnej pracy zaproponowano więc trójwymiarową (3D) metodę powtórnego próbkowania z wykorzy-staniem próbek wód z kategorii zdarzeń rzadkich, tak by uzyskać zrównoważony zbiór danych. W oparciu o wirtualne punkty na trójwymiarowej siatce, wykorzystano trójwymiarową metodęśredniej ważonej odległością (Inverse Distance Weighing – IDW) do interpolacji stężenia jonów w wodach gruntowych w wirtualnych próbkach wody, w celu nadpróbkowania dla kategorii zdarzeń rzadkich. Studium przypadku kopalni węgla Gubei pokazuje, że metoda poprawia dokładność dopasowania modelu w oparciu o kryterium Bayesowskie o 5.25% (z 85.26% na 90.96 %). W szczególności, dokładność rozróżniania i dyskryminacji próbek należących do kategorii zdarzeń rzadkich wzrasta od 0% do 83.33%, co oznacza bardzo znaczna poprawę. Ponadto, wartość współczynnika Kappa wzrasta o 19.92%, od 52.26 % do 72.19%, tym samym podnosząc poziom zgodności metody z poziomu ogólnego na „znaczący”. Prowadzone przez nas badania mają poważne znaczenie z punktu widzenia udoskonalenia teorii leżących u podstaw metod i technik zapobiegania i kontroli wycieków wód kopalnianych.
Źródło:
Archives of Mining Sciences; 2019, 64, 2; 321-333
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nano-sized micelles formed by self-assembling of polylactide(ethylene glycol) block copolymers in aqueous solutions
Autorzy:
Yang, L.
Zhao, Z.
Wei, J.
Li, S.
Powiązania:
https://bibliotekanauki.pl/articles/284952.pdf
Data publikacji:
2007
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
kopolimery
copolymers
Źródło:
Engineering of Biomaterials; 2007, 10, no. 63-64; 16-18
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some aggregating operators based on the Choquet integral with fuzzy number intuitionistic fuzzy information and their applications to multiple attribute decision making
Autorzy:
Wei, G.
Lin, R.
Zhao, X.
Wang, H.
Powiązania:
https://bibliotekanauki.pl/articles/206346.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
fuzzy number intuitionistic fuzzy values
operational laws
fuzzy number intuitionistic fuzzy Choquet ordered averaging (FNIFCOA) operator
fuzzy number intuitionistic fuzzy Choquet ordered geometric mean (FNIFCOGM) operator
Opis:
With respect to multiple attribute decision making (MADM) problems in which attribute values take the form of fuzzy number intuitionistic fuzzy values, a new decision making analysis method is developed. First, some operational laws of fuzzy number intuitionistic fuzzy values, score function and accuracy function of fuzzy number intuitionistic fuzzy values are introduced. Then, we have developed two fuzzy number intuitionistic fuzzy Choquet integral aggregation operators: fuzzy number intuitionistic fuzzy Choquet ordered averaging (FNIFCOA) operator and fuzzy number intuitionistic fuzzy Choquet ordered geometric mean (FNIFCOGM) operator. The prominent characteristic of the operators is that they can not only consider the importance of the elements or their ordered positions, but also reflect the correlation among the elements or their ordered positions. We have studied some desirable properties of the FNIFCOA and FNIFCOGM operators, such as commutativity, idempotency and monotonicity, and applied the FNIFCOA and FNIFCOGM operators to multiple attribute decision making with fuzzy number intuitionistic fuzzy information. Finally an illustrative example has been given to show the developed method.
Źródło:
Control and Cybernetics; 2012, 41, 2; 463-480
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on mechanical characteristics of rock type I fracture and anchorage strengthening mechanism
Autorzy:
Zhang, Wei
Zhao, Tongbin
Guo, Weiyao
Xing, Minglu
Powiązania:
https://bibliotekanauki.pl/articles/2104761.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
anchor rock
fracture type of I
fracture toughness
three-point bending test
toughening
Opis:
Engineering rocks are easily affected by excavation unloading and are in uniaxial compres- sion or tension, forming a typical I-type tension crack. Anchor rods are often used for on-site support to ensure safety and reliability of the project. The study of propagation and pen- etration of type I tension cracks and quantitative evaluation of rock anchoring effects are of great significance for exploring mechanical properties of rock fracture and revealing the mechanism of rock failure. In this paper, combined with speckle light measurement, a rock fracture toughness test of different anchoring positions and pre-tightening forces is carried out, the deformation evolution law of the crack tip and the fracture mechanics characteris- tics of the anchored rock are obtained, and the anchoring strengthening mechanism of the rock is discussed based on the theory of the net stress intensity factor. The research shows that the rock fracture process is divided into four stages: elastic deformation, steady crack propagation, crack instability propagation and residual deformation. After anchoring, the time of crack instability growth can be prolonged by 172% and the final residual deformation can be increased by 148%. Compared with the unanchored rock, the fracture toughness of rock initiation and instability increased by 83% and 124% respectively, and increased with growth of the pre-tightening force, which shows that the bolt increases the critical value of rock initiation and instability to achieve the toughening effect. After the rock is anchored, the time required for the crack to propagate to the same length increases by 55%, and the lateral deformation area is reduced by 46%, indicating that the lateral closing force of the bolt inhibits crack propagation and delays the instability of the rock matrix.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 3; 423--434
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal and mechanical properties of poly(L-lactic acid) nucleated with N,N’-bis(phenyl) 1,4-naphthalenedicarboxylic acid dihydrazide
Właściwości termiczne i mechaniczne poli(kwasu L-mlekowego) zarodkowanego dihydrazydem kwasu N,N’-bis(fenylo) 1,4-naftalenodikarboksylowego
Autorzy:
Zhao, Li-Sha
Qiao, Jun
Chen, Wei
Cai, Yan-Hua
Powiązania:
https://bibliotekanauki.pl/articles/1789985.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
poly(L-lactic acid)
phenyl hydrazine
nucleation effect
non-isothermal crystallization
mechanical properties
poli(kwas L-mlekowy)
fenylohydrazyna
efekt zarodkowania
krystalizacja nieizotermiczna
właściwości mechaniczne
Opis:
The modified poly(L-lactic acid) (PLLA) with different contents (0.5−3 wt %) of N,N’-bis(phenyl) 1,4-naphthalenedicarboxylic acid dihydrazide (NAPH) were prepared to evaluate effects of NAPH on melt-crystallization behavior (DSC), thermal degradation (TGA) and mechanical properties of PLLA. The melt-crystallization results demonstrated that NAPH as a heterogeneous organic nucleating agent enhanced crystallization ability of PLLA in cooling, and PLLA/1%NAPH had the best crystallization ability because of the highest onset crystallization temperature and the sharpest melt-crystallization peak. However, melt-crystallization behavior also depended on the cooling rate and final melting temperature, overall, a relative slow cooling rate and low final melting temperature were beneficial for crystallization of PLLA. The cold-crystallization results indicated that NAPH had an inhibition for cold-crystallization process of PLLA, and the cold-crystallization peak shifted towards lower temperature and became wider with an increase of NAPH concentration. The different melting behaviors of PLLA/NAPH after melt-crystallization and isothermal-crystallization efficiently reflected the accelerating role of NAPH for PLLA crystallization; the double melting peaks formed in heating were thought to result from melting-recrystallization, as well as that a higher crystallization temperature could cause melting peak to appear in higher temperature regions and possess larger melting enthalpy. A comparative analysis on thermal degradation in air illustrated that the addition of NAPH accelerated decomposition of PLLA, but a decrease of onset decomposition temperature was inhibited by the probable interaction of PLLA with NAPH. Moreover, the tensile test showed that NAPH decreased tensile modulus and elongation at break of PLLA, whereas PLLA with low concentration of NAPH had higher tensile strength than pure PLLA.
Poli(kwas L-mlekowy) (PLLA) modyfikowano dodatkiem 0,5−3 % mas. dihydrazydu kwasu N,N’-bis(fenylo) 1,4-naftalenodikarboksylowego (NAPH). Zbadano wpływ NAPH na topnienie i krystalizację (DSC), degradację termiczną (TGA) i właściwości mechaniczne PLLA. Analiza procesu krystalizacji ze stanu stopionego modyfikowanego PLLA wykazała, że NAPH, jako heterogeniczny organiczny środek zarodkujący, zwiększał zdolność do krystalizacji PLLA podczas chłodzenia, a próbka PLLA/1% NAPH charakteryzowała się najwyższą temperaturą początku krystalizacji i najostrzejszym pikiem krystalizacji ze stanu stopionego. Przebieg procesu krystalizacji zależał również od szybkości chłodzenia i końcowej temperatury topnienia próbki. Względnie mała szybkość chłodzenia i niska końcowa temperatura topnienia były korzystne dla procesu krystalizacji PLLA. Analiza procesu zimnej krystalizacji wskazała, że obecność NAPH hamowała zimną krystalizację PLLA, jej pik przesuwała w kierunku niższych wartości temperatury, a wraz ze wzrostem stężenia NAPH pik stawał się szerszy. Różny przebieg procesów topnienia PLLA/NAPH po krystalizacji ze stanu stopionego i krystalizacji izotermicznej odzwierciedla przyspieszającą rolę NAPH w krystalizacji PLLA. Autorzy uważają, że podwójne piki topnienia powstające podczas ogrzewania wynikają z zachodzącego procesu topnienia-rekrystalizacji, a także, że wyższa temperatura krystalizacji może być przyczyną pojawienia się piku topnienia w obszarach wyższej temperatury i zwiększenia entalpii topnienia. Analiza porównawcza rozkładu termicznego w atmosferze powietrza wykazała, że dodatek NAPH przyspieszył rozkład PLLA, ale prawdopodobne oddziaływanie PLLA z NAPH wpłynęło na zmniejszenie temperatury początku rozkładu. Ponadto, dodatek większej ilości NAPH spowodował zmniejszenie modułu sprężystości przy rozciąganiu i wydłużenia przy zerwaniu PLLA, jednak PLLA zawierający niewielką ilość NAPH wykazywał większą wytrzymałość na rozciąganie niż niemodyfikowany PLLA.
Źródło:
Polimery; 2021, 66, 4; 234--244
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rare Earth Elements supply vs. clean energy technologies: new problems to be solve
Dostawy pierwiastków ziem rzadkich (REE) a czyste technologie energetyczne: nowe problemy do rozwiązania
Autorzy:
Zhou, B.
Li, Z.
Zhao, Y.
Zhang, C.
Wei, Y.
Powiązania:
https://bibliotekanauki.pl/articles/216173.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
rare earth element
clean energy technology
supply chain
pierwiastki ziem rzadkich
czysta technologia energetyczna
łańcuch dostaw
Opis:
Rare earth elements (REEs) provide important properties to clean energy technologies such as wind turbine and hybrid electric vehicles. The global REE demand will grow rapidly during the global transformation toward a greener economy in the next decades. This high demand will require a steady supply chain in the long run. China has a monopoly of global REE production and extraction. The global REE supply chain runs the risk of disruption along with Chinese REE policy evolution. To overcome this supply chain vulnerability, new strategies and measures should be adopted to satisfy future REE supply/demand. There is a pressing need to explore REE deposits, develop efficient REE recycling techniques from end-of-life products, improve substitution technologies for REEs, and reduce the number of critical REEs used in devices. Such measures are facing significant challenges due to environmental factors and an unbalanced market, and overcoming them requires efforts from government and REE companies.
Pierwiastki ziem rzadkich (Rare Earths Elements) mają istotne znaczenie dla rozwoju czystych technologii energetycznych, takich jak turbiny wiatrowe czy pojazdy hybrydowe. Światowy popyt na REE będzie wzrastał w związku z globalną transformacją w kierunku bardziej czystej (ekologicznej) gospodarki w okresie najbliższych dziesięcioleci. Wysoki popyt wymagać będzie stabilnego łańcucha dostaw REE w dłuższej perspektywie. Chiny mają monopol w zakresie globalnej produkcji i wydobycia REE. Światowe dostawy REE obarczone są jednak ryzykiem zakłóceń wynikających z chińskiej polityki w tym zakresie. W związku z tym, powinny być przyjęte nowe środki i strategie w celu zaspokojenia przyszłego popytu/podaży na REE. Istnieje pilna konieczność: poszukiwania nowych złóż, opracowania skutecznych technik recyklingu z wycofanych z eksploatacji produktów, poprawy technologii z zastosowaniem substytutów REE oraz zmniejszenie liczby krytycznych pierwiastków ziem rzadkich w stosowanych urządzeniach. Działania te stanowią poważne wyzwanie ze względu na czynniki środowiskowe i niezrównoważony rynek (monopol podaży). Przezwyciężenie ich wymaga odpowiednich działań ze strony rządu i firm zajmujących się produkcją REE.
Źródło:
Gospodarka Surowcami Mineralnymi; 2016, 32, 4; 29-44
0860-0953
Pojawia się w:
Gospodarka Surowcami Mineralnymi
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of Clothing Image Classification Models: A Comparison Study between Traditional Machine Learning and Deep Learning Models
Autorzy:
Xu, Jun
Wei, Yumeng
Wang, Aichun
Zhao, Heng
Lefloch, Damien
Powiązania:
https://bibliotekanauki.pl/articles/2200761.pdf
Data publikacji:
2022
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
e-commerce
clothing image classification
traditional machine learning
CNN
HOG
SVM
small VGG network
Opis:
Clothing image in the e-commerce industry plays an important role in providing customers with information. This paper divides clothing images into two groups: pure clothing images and dressed clothing images. Targeting small and medium-sized clothing companies or merchants, it compares traditional machine learning and deep learning models to determine suitable models for each group. For pure clothing images, the HOG+SVM algorithm with the Gaussian kernel function obtains the highest classification accuracy of 91.32% as compared to the Small VGG network. For dressed clothing images, the CNN model obtains a higher accuracy than the HOG+SVM algorithm, with the highest accuracy rate of 69.78% for the Small VGG network. Therefore, for end-users with only ordinary computing processors, it is recommended to apply the traditional machine learning algorithm HOG+SVM to classify pure clothing images. The classification of dressed clothing images is performed using a more efficient and less computationally intensive lightweight model, such as the Small VGG network.
Źródło:
Fibres & Textiles in Eastern Europe; 2022, 5 (151); 66--78
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on the influence of rotational speed on the performance of high-speed permanent-magnet generator
Autorzy:
Qiu, Hongbo
Wei, Yanqi
Zhao, Xi Fang
Yang, Cunxiang
Yi, Ran
Powiązania:
https://bibliotekanauki.pl/articles/141641.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high-speed permanent-magnet generator (HSPMG)
harmonic content
maximum power
overload capacity
voltage regulation
Opis:
When the machine is at high speed, serious problems occur, such as high frequency loss, difficult thermal management, and the rotor structural strength insufficiency. In this paper, the performances of two high-speed permanent magnet generators (HSPMGs) with different rotational speeds and the same torque are compared and analyzed. The two-dimensional finite element model (FEM) of the 117 kW, 60 000 rpm HSPMG is established. By comparing a calculation result and test data, the accuracy of the model is verified. On this basis, the 40 kW, 20 000 rpm HSPMG is designed and the FEM is established. The relationship between the voltage regulation sensitivity and power factor of the two HSPMGs is determined. The influence mechanism of the voltage regulation sensitivity is further revealed. In addition, the air-gap flux density is decomposed by the Fourier transform principle, and the influence degree of different harmonic orders on the HSPMG performance is determined. The method to reduce the harmonic content is further proposed. Finally, the method to improve the HSPMG overload capacity is obtained by studying the maximum power. The research showed that the HSPMG at low speed (20 000 rpm) has high sensitivity of the voltage regulation, while the HSPMG at high speed (60 000 rpm) is superior to the HSPMG at low speed in reducing the harmonic content and increasing the overload capacity.
Źródło:
Archives of Electrical Engineering; 2019, 68, 1; 77-90
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bulldoze and rebuild: Modifying cratonic lithosphere via removal and replacement induced by continental subduction
Autorzy:
Meng, Lingtong
Chu, Yang
Lin, Wei
Mitchell, Ross N.
Zhao, Liang
Powiązania:
https://bibliotekanauki.pl/articles/24202141.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
lithosphere
China
Opis:
Establishing the mechanisms for craton modification is critical for understanding cratonic stability and architecture. Both plate tectonics and mantle plumes can cause weakening, mechanical decoupling, and even lithospheric removal. But craton modification  – craton destruction accompanied or followed by craton rejuvenation  – has received less attention. It is well-known that oceanic subduction dominantly destroys cratonic lithosphere with replacement to a lesser degree, and mantle plumes have been related to both destruction and rejuvenation. The role of continental subduction in craton modification, however, remains a comparatively open question. The North China Craton, as a previously stable continent with a lithosphere of more than 200 km since the Paleoproterozoic, was reworked and substantially destroyed since the Mesozoic, with intensive destruction occurring in the Early Cretaceous. Earlier in the Mesozoic, North China Craton experienced a continent-continent collision (as the upper plate) with the South China Block, forming the Sulu orogenic belt, providing an opportunity to understand the potential for craton modification due to deep continental subduction In the North China craton, we report the presence of material (i.e., Yunshan unit) sourced from the underlying subducted plate. It is composed of foliated monzonitic granite and metamorphic sedimentary rocks that locally experienced crustal anatexis. Through detailed zircon U-Pb dating, it formed at latest Triassic (ca. 212 Ma). Importantly, the 800–700 Ma inherited zircons from the Yunshan foliated granite resemble those from the South China Block rather than the North China Craton. According to structural and magnetic data, the fabrics of the Yunshan foliated granite, characterized by gentle magnetic/mesoscopic foliations and conspicuous NW-SE-trending magnetic/mesoscopic lineations with a top-to-the-NW shearing. Its geometry, kinematics, and timing all compare favorably with the latest Triassic extensional structure accounting for the exhumation of the Sulu orogenic belt. We thus interpret the Yunshan unit to have been sourced from the subducted South China Block, then exhumed and emplaced into the overriding North China Craton (Fig. 1A). Combining our new results with previous geological and geophysical data, we argue that from 250–220 Ma a 200-km-long tract of North China Craton lithosphere was bulldozed by the subducted South China Block, resulting in a lithospheric suture far from the suture zone at the surface. This lithospheric removal occurred at mid-lower crustal levels (16–20 km depth)  – much shallower than previously thought possible. The bulldozed North China Craton lithosphere was simultaneously replaced by the reworked underlying South China Block plate. Such a “bulldoze and rebuild” lithospheric modification process minimized asthenosphere-lithosphere interaction, thus preventing the North China Craton from further modification (Fig. 1B–1D). Because there was essentially no net loss of lithosphere during deep continental subduction, the North China Craton largely maintained its stability for the time and did not suffer intensive destruction until later Early Cretaceous palaeo-Pacific oceanic subduction. This “bulldoze and rebuild” model can thus account for how a craton can maintain its stability during a collision with another continental plate.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 47--48
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
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