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Wyświetlanie 1-10 z 33
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
Wyświetlanie 1-10 z 33

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