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Tytuł:
Application cumulative tensile explosions for roof cutting in Chinese underground coal mines
Autorzy:
Yang, Jun
Liu, Binhui
Bian, Wenhui
Chen, Kuikui
Wang, Hongyu
Cao, Chen
Powiązania:
https://bibliotekanauki.pl/articles/2073869.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
roboty strzałowe
wysadzanie skał
kopalnia
cumulative blast
bilateral cumulative tensile explosion
roof cutting and pressure relief technology
gob-side entry retaining
Opis:
Cumulative blasts are an important controlled blasting method used to control the propagation of cracks in the predetermined direction. However, traditional cumulative blasts are associated with long processing times and poor blasting effects. A simple blasting technology called bilateral cumulative tensile explosion (BCTE) is proposed in this paper. There are two application types where BCTE is used. The first application is used to control the stability of high-stress roadways in both Wangzhuang mine 6208 tailgate and Hongqinghe mine 3-1103 tailgate. The second application is used to replace the backfill body in gob-side entry retaining (GER) in Chengjiao mine 21404 panel, Jinfeng mine 011810 panel and Zhongxing mine 1200 panel. The first application type reveals that BCTE can significantly reduce the deformation of the surrounding rock and reduce the associated maintenance cost of the roadways. Whereas the second application type, the roadway deformations are smaller, the process is simpler, and the production costs are lower, which further promotes GER and is of significance towards conserving resources.
Źródło:
Archives of Mining Sciences; 2021, 66, 3; 421--435
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on intensive design and control of chamber group under the condition of weak surrounding rock
Autorzy:
Yang, Jun
Hou, Shilin
Zhou, Kaifang
Qiao, Bowen
Wang, Hongyu
Wei, Qinglong
Powiązania:
https://bibliotekanauki.pl/articles/88879.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
Tematy:
deep soft rock
chamber group
intensive design
field test
surrounding rock control
Opis:
In order to study the design and stability control of deep soft rock chamber group, taking ninth coal mine of Hebi Coal Power Co., Ltd. as the engineering background, The main problem in normal design is analyzed with the combined method of FLAC3D numerical simulation and field engineering test. and then puts forward targeted control measures and carries out field application. The results show that, compared with the conventional design, the intensive design can reduce the stress concentration degree and plastic zone range of the surrounding rock, as well as reduce the quantities. Compared with conventional supporting schemes, the surrounding rock deformation greatly reduces by more than 82% after adopting bolting and shotcreting with wire mesh + anchor cable + floor anchor supporting. Among them, the floor heave control has obvious effect, and the decreasing amplitude reaches more than 93%. The field application shows that the surrounding rock deformation of the main chamber is within the allowable range, and the chamber control effect is good. Therefore, the research results can provide reference for the design and control of similar chamber groups.
Źródło:
Mining Science; 2019, 26; 223-240
2300-9586
2353-5423
Pojawia się w:
Mining Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on Scattering Feature Extraction of Underwater Moving Cluster Targets Based on the Highlight Model
Autorzy:
Yang, Yang
Fan, Jun
Wang, Bing
Powiązania:
https://bibliotekanauki.pl/articles/31339855.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
motion small cluster targets
feature fusion
azimuth trend scale
azimuth trend Doppler
Opis:
In detecting cluster targets in ports or near-shore waters, the echo amplitude is seriously disturbed by interface reverberation, which leads to the distortion of the traditional target intensity characteristics, and the appearance of multiple targets in the same or adjacent beam leads to fuzzy feature recognition. Studying and extracting spatial distribution scale and motion features that reflect the information on cluster targets physics can improve the representation accuracy of cluster target characteristics. Based on the highlight model of target acoustic scattering, the target azimuth tendency is accurately estimated by the splitting beam method to fit the spatial geometric scale formed by multiple highlights. The instantaneous frequencies of highlights are extracted from the time-frequency domain, the Doppler shift of the highlights is calculated, and the motion state of the highlights is estimated. Based on the above processing method, target highlights’ orientation, spatial scale and motion characteristics are fused, and the multiple moving highlights of typical formation distribution in the same beam are accurately identified. The features are applied to processing acoustic scattering data of multiple moving unmanned underwater vehicles (UUVs) on a lake. The results show that multiple small moving underwater targets can be effectively recognized according to the highlight scattering characteristics.
Źródło:
Archives of Acoustics; 2023, 48, 3; 235-247
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculation of the dynamic characteristics of ship’s aft stern tube bearing considering journal deflection
Autorzy:
Yang, Hongjun
Li, Jun
Li, Xiaolong
Powiązania:
https://bibliotekanauki.pl/articles/259603.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
journal deflection
aft stern tube bearing
dynamic characteristic
Opis:
Dynamic properties are vital for the working reliability of aft stern tube bearings. However, the determination of such properties currently involves several simplifications and assumptions. To obtain its dynamic characteristics accurately, the aft stern tube bearing was divided into several bearing segments. The oil film reaction force was considered in the calculation of shaft alignment, and the journal deflection and actual oil film thickness were obtained accordingly. Subsequently, the perturbed Reynolds equation was solved using the finite difference method when the dynamic characteristics of journal bearings with finite width were evaluated. Then, a calculation program was developed and verified by comparing with the results of other studies. Finally, the dynamic characteristics were calculated under different revolutions. The results showed that the stiffness at the vertical direction of the aft stern tube bearing was several times that of the horizontal direction and varied with the revolutions of the shafting system. These findings can provide the foundation for the precise calculation of the journal trajectory under dynamic conditions, as well as for the evaluation of the oil film thickness. Moreover, the results led to favorable conditions for the accurate calculation of the shafting whirling vibration.
Źródło:
Polish Maritime Research; 2020, 1; 107-115
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessing system impedance based on data regrouping
Autorzy:
Xu, Shuangting
Xiao, Xianyong
Wang, Yang
Wu, Jun
Powiązania:
https://bibliotekanauki.pl/articles/1848954.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
system impedance
passive method
Thevenin equivalent
power system
Opis:
In recent years, assessing supply system impedance has become crucial due to the concerns on power quality and the proliferation of distributed generators. In this paper, a novel method is shown for passive measurement of system impedances using the gapless waveform data collected by a portable power quality monitoring device. This method improves the overall measurement accuracy through data regrouping. Compared with the traditional methods that use the consecutive measurement data directly, the proposed method regroups the data to find better candidates with less flotation on the system side. Simulation studies and extensive field tests have been conducted to verify the effectiveness of the proposed method. The results indicate that the proposed method can serve as a useful tool for impedance measurement tasks performed by utility companies.
Źródło:
Metrology and Measurement Systems; 2021, 28, 1; 191-208
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical study on dynamic response of cantilever flexible retaining wall
Autorzy:
Yang, Xiuzhu
Liu, Xinyuan
Zhao, Shuang
Yu, Jun
Powiązania:
https://bibliotekanauki.pl/articles/27312122.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
analiza sejsmiczna
ścianka wspornikowa
ściana elastyczna
ściana oporowa
mechanika falowa
odpowiedź dynamiczna
rozwiązanie analityczne
seismic analysis
cantilever wall
flexible wall
retaining wall
wave mechanics
dynamic response
analytic solution
Opis:
Based on wave mechanics theory, the dynamic response characteristics of cantilever flexible wall in two-dimensional site are analyzed. The partial derivative of the vibration equation of soil layer is obtained, and the general solution of the volume strain is obtained by the separation of variables method. The obtained solution is substituted back to the soil layer vibration equation to obtain the displacement vibration general solution. Combined with the soil-wall boundary condition and the orthogonality of the trigonometric function, the definite solution of the vibration equation is obtained. The correctness of the solution is verified by comparing the obtained solution with the existing simplified solution and the solution of rigid retaining wall, and the applicable conditions of each simplified solution are pointed out. Through parameter analysis, it is shown that when the excitation frequency is low, the earth pressure on the wall is greatly affected by the soil near the wall. When the excitation frequency is high, the influence of the far-field soil on the earth pressure of the wall gradually increases. The relative stiffness of the wall, the excitation frequency and the soil layer damping factor have a significant effect on the dynamic response of the flexible retaining wall.
Źródło:
Archives of Civil Engineering; 2023, 69, 2; 435--453
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrafiltration treatment of wastewater contained heavy metals complexed with palygorskite
Autorzy:
Ren, Jun
Cao, Tiany
Yang, Xin
Tao, Ling
Powiązania:
https://bibliotekanauki.pl/articles/778555.pdf
Data publikacji:
2020
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
palygorskite
heavy metals
ultrafiltration
complexation
pH
ionic strength
Opis:
Palygorskite was applied in complexation-ultrafiltration treatment of heavy metals in wastewater under different pH and ionic strength. The results indicated that the rejection of heavy metals increased significantly with pH value, and decreased slightly with an increase of ionic strength of Na+ and Cl-. A certain concentration of NaCl significantly reduced the rejection rate of Cu2+. The rejection of Cu2+, Zn2+ and Cd2+ could reach over 86.8%, 93.6% and 93.7% at pH of 7 and 0.1 mol/L NaCl. The rejection of heavy metals was severely affected by low molecular weight competing complexing agents and the effect of sodium tartrate was greater than triethanolamine. In the presence of sodium tartrate, the rejection of Cu2+, Zn2+ and Cd2+ could arrive over 81.4%, 57.6% and 60.5% at pH of 7 in 20 min. Palygorskite was offered a potential complexing agent for the removal of heavy metals in wastewater at the complexation-ultrafiltration process.
Źródło:
Polish Journal of Chemical Technology; 2020, 22, 4; 1-9
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessing system impedance based on data regrouping
Autorzy:
Xu, Shuangting
Xiao, Xianyong
Wang, Yang
Wu, Jun
Powiązania:
https://bibliotekanauki.pl/articles/1848965.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
system impedance
passive method
Thevenin equivalent
power system
Opis:
In recent years, assessing supply system impedance has become crucial due to the concerns on power quality and the proliferation of distributed generators. In this paper, a novel method is shown for passive measurement of system impedances using the gapless waveform data collected by a portable power quality monitoring device. This method improves the overall measurement accuracy through data regrouping. Compared with the traditional methods that use the consecutive measurement data directly, the proposed method regroups the data to find better candidates with less flotation on the system side. Simulation studies and extensive field tests have been conducted to verify the effectiveness of the proposed method. The results indicate that the proposed method can serve as a useful tool for impedance measurement tasks performed by utility companies.
Źródło:
Metrology and Measurement Systems; 2021, 28, 1; 191-208
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Camouflage Assessments with Digital Pattern Painting Based on the Multi-Scale Pattern-in-Picture Evaluation Model
Autorzy:
Jia, Qi
Xu, Weidong
Yi, Yang
Liu, Jun
Hu, Jianghua
Zhu, Liyan
Yang, Xin
Powiązania:
https://bibliotekanauki.pl/articles/24200962.pdf
Data publikacji:
2023
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
computer-aided
camouflage assessment
pattern painting
evaluation
simulation
military camouflage
Opis:
In general, traditional evaluations of target camouflage effects are usually conducted based on observational data and general results of statistical analysis. This widely applied methodology quantifies the detection and identification probabilities of camouflage objects but has considerable shortcomings. This data evaluation process is laborious and time-consuming and very low in reproducibility, which sheds light on the necessity of developing a more efficient method in this study field. The growth of computeraided image processing technology provides technical support for camouflage effect evaluation based on digital image processing. Digital pattern painting, which has been previously applied to combat utility uniforms, is a new methodology full of potential due to its broad geographical adaptability. This study proposes a multi-scale pattern-in-picture method to evaluate camouflage effects at different distances. We also established a computer-aided background image library and camouflage assessments with digital simulation and created an evaluation system that could be effectively applied to combat utility uniforms. More than 40 testers participated in this study, who were asked to score the designed camouflage schemes using the evaluation system proposed. The data from simulation assessments and individual evaluations show that the computer-aided simulation assessments conducted as part of this research can efficiently and objectively evaluate the camouflage effect on military objects.
Źródło:
Fibres & Textiles in Eastern Europe; 2023, 31, 2; 39--50
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Trade Openness, Political Stability and Environmental Performance: What Kind of Long-Run Relationship?
Otwartość w handlu, stabilność polityczna i wydajność środowiskowa: jaki rodzaj długotrwałej relacji?
Autorzy:
Niu, Jing
Wen, Jun
Yang, Xiu-Yun
Chang, Chun-Ping
Powiązania:
https://bibliotekanauki.pl/articles/973022.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Komitet Człowiek i Środowisko PAN
Tematy:
political stability
trade openness
Environmental Performance Index
Panel Cointegration
causality
stabilność polityczna
otwartość w handlu
Indeks Wydajności Środowiskowej
Panel Kointegracyjny
przyczynowość
Opis:
This paper investigates the long-run relationships among environmental performance, political stability, and trade openness for 126 countries as well as the sub-samples of OECD and non-OECD countries, using the panel cointegration and panel-based error correction models for the period 2002-2014. For the full sample and the non-OECD countries, our results corroborate that there exists a long-term equilibrium cointegrated relationship among the variables. Moreover, the panel fully modified ordinary least square (FMOLS) estimations present that political stability and trade openness have a negative effect on environmental performance in full samples case as well as the non-OECD countries, whereas trade openness exhibits a positive influence on environmental performance in OECD countries. The vector error correction model (VECM) shows a diversified negative causalities running from trade openness and political stability to environmental performance in the long run for both full samples and the sub-samples countries. The policy implication is that pollution haven hypothesis (PHH) is supported and trade regulations can help promote environmental performance; meanwhile, political stability accelerates macroeconomic performance and attracts more foreign investment. Overall, the government can carry on a policy to lower pollution levels, thus further advancing environmental performance.
W niniejszym artykule przeanalizowano długoterminowe relacje pomiędzy wydajnością środowiskową, stabilnością polityczną i otwartością handlu w 126 krajach, a także pod-próbki krajów OECD i spoza OECD, z wykorzystaniem kointegracji panelowej i panelowych modeli korekcji błędów za lata 2002-2014. W przypadku całej próby i krajów spoza OECD nasze wyniki potwierdzają, że między zmiennymi istnieje długookresowa równowagowa zależność. Co więcej, panel FMOLS wskazuje, że stabilność polityczna i otwartość handlu mają negatywny wpływ na wydajność środowiskową w przypadku pełnych próbek, jak również w krajach nienależących do OECD, podczas gdy otwartość handlowa ma pozytywny wpływ na wydajność środowiskowe w krajach OECD. Model VECM pokazuje zróżnicowane negatywne przyczyny, które wynikają z otwartości handlowej i stabilności politycznej na wydajność środowiskową w dłuższej perspektywie, zarówno dla pełnych próbek, jak i dla podpróbek. Konsekwencją polityczną jest to, że hipoteza PHH (pollution haven hypothesis) jest wspierana, a regulacje handlowe mogą pomóc w promowaniu wydajności środowiskowej; tymczasem stabilność polityczna przyspiesza wyniki makroekonomiczne i przyciąga więcej inwestycji zagranicznych. Ogólnie rzecz biorąc, rząd może prowadzić politykę mającą na celu obniżenie poziomu zanieczyszczeń, a tym samym umożliwia dalszy postęp w dziedzinie ochrony środowiska.
Źródło:
Problemy Ekorozwoju; 2018, 13, 2; 57-66
1895-6912
Pojawia się w:
Problemy Ekorozwoju
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation Evaluation Method for Fusion Characteristics of the Optical Camouflage Pattern
Metoda oceny symulacji charakterystyk wzoru kamuflażu optycznego
Autorzy:
Yang, Xin
Xu, Wei-Dong
Liu, Jun
Jia, Qi
Zhu, Wan-Nian
Powiązania:
https://bibliotekanauki.pl/articles/1419455.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
camouflage pattern evaluation
effect evaluation
sampling statistics
visual feature
kamuflaż
efekt oddziaływania
próbkowanie
funkcja wizualna
Opis:
A comprehensive evaluation system for a camouflage design combining local effect evaluation and global sampling is developed. Different from previous models, this method can sample and evaluate target camouflage in a wide range of combat areas, thereby obtaining a comprehensive evaluation effect. In evaluating local effects, the Gaussian pyramid model is adopted to decompose the image on a multi-scale so that it can conform to the multi-resolution property of human eyes. The Universal Image Quality Index (UIQI) conforming to features of eye movements is then adopted to measure the similarities between multi-scale targeted and background brightness, color and textural features. In terms of the imitation camouflage pattern design algorithm, uniform sampling is used to obtain the evaluation distribution in the background; while for the deformation camouflage pattern, the sampling distribution is improved to make it conform to the movement rule of the target in the background. The evaluation results of the model for different designs were investigated. It is suggested by the experimental results that the model can compare and evaluate the indicators involved in the process of camouflage design, including integration, polychromatic adaptability and algorithm stability. This method can be applied in the evaluation and contrast of camouflage pattern design algorithms, in parameter optimisation of camouflage design and in scheme comparison in engineering practice, and can provide support of evaluation methodology for camouflage design theories.
W pracy opracowano kompleksowy system oceny projektu kamuflażu, łączący ocenę efektu lokalnego i próbkowanie globalne. W odróżnieniu od poprzednich modeli, ta metoda może próbkować i oceniać kamuflaż celu w szerokim zakresie obszarów walki, uzyskując w ten sposób kompleksowy efekt oceny. Oceniając efekty lokalne, przyjęto model piramidy Gaussa w celu dekompozycji obrazu w wielu skalach, tak aby mógł on być zgodny z właściwościami i rozdzielczością ludzkiego oka. Następnie przyjęto uniwersalny wskaźnik jakości obrazu (UIQI) zgodny z cechami ruchów oczu, tak aby zmierzyć podobieństwa między celowaniem w wielu skalach a jasnością tła, kolorem i cechami tekstury. Jeśli chodzi o algorytm projektowania imitacji wzoru kamuflażu, w celu uzyskania rozkładu oceny w tle zastosowano jednolite próbkowanie; podczas gdy w przypadku wzoru kamuflażu deformacji poprawiono rozkład próbkowania, tak aby był zgodny z regułą ruchu celu w tle. Zbadano wyniki oceny modelu dla różnych projektów. Wyniki eksperymentów wykazały, że model może służyć do porównania i oceny wskaźników procesu projektowania kamuflażu, w tym integrację, polichromatyczną adaptowalność i stabilność algorytmu. Metoda przedstawiona w pracy może znaleźć zastosowanie w ocenie algorytmów projektowania wzorów kamuflażu, w optymalizacji parametrów projektowania kamuflażu i przy porównywaniu schematów w praktyce inżynierskiej, a także może stanowić wsparcie dla metodologii oceny teorii projektowania kamuflażu.
Źródło:
Fibres & Textiles in Eastern Europe; 2021, 3 (147); 103-110
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Linear operators preserving maximal column ranks of nonbinary boolean matrices
Autorzy:
Song, Seok-Zun
Yang, Sung-Dae
Hong, Sung-Min
Jun, Young-Bae
Kim, Seon-Jeong
Powiązania:
https://bibliotekanauki.pl/articles/728798.pdf
Data publikacji:
2000
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
Boolean matrix
semiring
linear operator on matrices
congruence operator on matrices
maximal column rank of a matrix
Boolean rank of a matrix
Opis:
The maximal column rank of an m by n matrix is the maximal number of the columns of A which are linearly independent. We compare the maximal column rank with rank of matrices over a nonbinary Boolean algebra. We also characterize the linear operators which preserve the maximal column ranks of matrices over nonbinary Boolean algebra.
Źródło:
Discussiones Mathematicae - General Algebra and Applications; 2000, 20, 2; 255-265
1509-9415
Pojawia się w:
Discussiones Mathematicae - General Algebra and Applications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of a water hammer and cavitation on vibration transients in a reservoir-pipe-valve system
Autorzy:
Miao, Yang
Qiu, Zaihui
Zhang, Xiaolu
Jiang, Yuncheng
Pan, Jun
Liu, Yi
Zhang, Li
Li, Kun
Powiązania:
https://bibliotekanauki.pl/articles/2055065.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
reservoir-pipe-valve system (RPV system)
water hammer
vibration
cavitation
Opis:
An extraordinary phenomenon with violent oscillation, accompanied by an abnormal “click” sound is observed during the valve closing in a fuel feeding pipe system. A fluctuation model with flow cavitation, in which time-varying stiffness, time-varying damping coefficients and flow cavitation are comprehensively considered, is proposed. On this basis, a dynamic vibration equation is established and an expression of flow pressure at the valve port is derived. The critical displacement of the flow cavitation system is defined. When the vibration amplitude reaches the critical displacement, cavitation occurs. Based on this model, simulation of vibration displacement and flow pressure is given. The simulated transient process shows the phenomena of vibration fluctuation with cavitation. The results are compared with the experimental data measured by a pressure sensor. Under our experimental conditions, the critical displacement of vibration is 1.41mm, and the average relative pressure peak error is 0.022. The comparison between the simulation and experimental results shows that they are in an acceptable agreement.
Źródło:
Journal of Theoretical and Applied Mechanics; 2021, 59, 4; 611--622
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of cations on rare earth adsorption and desorption in binding sites of montmorillonite
Autorzy:
He, Zhengyan
Nie, Wenrui
Yang, Huifang
Tang, Yuchen
Sha, Aoyang
Qu, Jun
Xu, Zhigao
Chi, Ruan
Powiązania:
https://bibliotekanauki.pl/articles/24085808.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
adsorption
desorption
external site
interlayer site
basal spacing
Opis:
The exchangeability of rare earth (RE) in weathered crust elution-deposited rare earth ores largely depends on its interaction with clay minerals, which may be significantly influenced by various cations. Therefore, the effects of K+, Ca2+ and Al3+ on RE3+ adsorption and desorption in binding sites of montmorillonite (MMT) were investigated. Through the pre-saturation, the interlayer ions of MMT had been replaced by K+, Ca2+ or Al3+. RE3+ can adsorb on the interlayer sites of Ca-MMT and K-MMT, but nearly not Al-MMT. The basal spacing of Ca-MMT is larger than K-MMT, which provides a smaller hinder effect of interlayer collapse for the interlayer diffusion of RE3+. The adsorption capacity followed the order: Ca-MMT＞K-MMT＞Al-MMT and La3+＞Y3+＞Eu3+. It can predict that the grade of the exchangeable RE in ores abundant in Ca2+ is the most, followed by the ore rich in K+ and Al3+ the least. Clay minerals tend to adsorb light RE and hard to adsorb middle and heavy RE. The reversibility of RE adsorbed in interlayers, especially in collapsed interlayers, is far worse than that on externals. The desorption rates of RE were in the order of RE-Al-MMT＞RE-K-MMT＞RE-Ca-MMT and Eu3+＞Y3+＞La3+. For the desorption of interlayer RE3+, NH4+ is better than Mg2+ because the larger change of the basal spacings (Δd) provides more minor activation energy barriers (ΔE) for NH4+ diffusion within interlayers. It can enrich the metallogeny theory of weathered crust elution-deposited rare earth ores and provide a certain theoretical basis for its efficient exploitation.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 3; art. no. 168280
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Determination of the Mechanical and Thermal Properties, and Impact Sensitivity of Pressed HMX-based PBX
Autorzy:
Li, Yuxiang
Wu, Peng
Hua, Cheng
Wang, Jun
Huang, Bing
Chen, Jin
Qiao, Zhiqiang
Yang, Guangcheng
Powiązania:
https://bibliotekanauki.pl/articles/358006.pdf
Data publikacji:
2019
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
nanoexplosives
impact sensitivity
particle size
hot spot
Opis:
Submicron- and nano-explosives have attracted growing attention, while the mechanism of how particle size influences the impact sensitivity is not completely understood. In the present work, HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) based PBXs (plastic bonded explosives) of three particle size distributions (1-2 and 10-20 μm, and 100-300 nm) and two pressed densities (91%TMD and 79%TMD) were characterized and tested with a range of techniques to determine their mechanical and thermal properties and impact sensitivities. The results demonstrated that with decreased particle size, the mechanical strength as well as the thermal conductivity were dramatically improved, and the impact sensitivity was significant decreased. The structure of impacted samples suggested that the ignition mechanism is dependant on the particle size. Samples with higher density were more sensitive to impact, as the impact force acting on these samples was higher. The correlation between particle size and impact sensitivity is discussed in detail.
Źródło:
Central European Journal of Energetic Materials; 2019, 16, 2; 295-315
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 17

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