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Tytuł:
Numerical checking method for positive invariance of polyhedral sets for linear dynamical systems
Autorzy:
Yang, H.
Hu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/200512.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
positively invariant sets
linear system
polyhedral set
polyhedral cone
linear programming
Opis:
Positively invariant sets play an important role in the theory and applications of dynamical systems. The stability in Lyapunov sense of equilibrium x = 0 is equivalent to the existence of the ellipsoidal positively invariant sets. The constraints on the state and control vectors of dynamical systems can be formulated as polyhedral positively invariant sets in practical engineering problems. Numerical checking method of positive invariance of polyhedral sets is addressed in this paper. The validation of the positively invariant sets can be done by solving LPs which can be easily implemented numerically. The effectiveness of the proposed checking method is illustrated by examples. Compared with the now existing algebraic methods, numerical checking method is attractive and, importantly, easy to be implemented.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 3; 593-599
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stability and stabilization of positive linear dynamical systems: new equivalent conditions and computations
Autorzy:
Yang, H.
Hu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/201932.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
positive linear systems
stability
stabilization
linear inequalities systems
consistency
I-rank
Opis:
New equivalent conditions of the asymptotical stability and stabilization of positive linear dynamical systems are investigated in this paper. The asymptotical stability of the positive linear systems means that there is a solution for linear inequalities systems. New necessary and sufficient conditions for the existence of solutions of the linear inequalities systems as well as the asymptotical stability of the linear dynamical systems are obtained. New conditions for the stabilization of the resultant closed-loop systems to be asymptotically stable and positive are also presented. Both the stability and the stabilization conditions can be easily checked by the so-called I-rank of a matrix and by solving linear programming (LP). The proposed LP has compact form and is ready to be implemented, which can be considered as an improvement of existing LP methods. Numerical examples are provided in the end to show the effectiveness of the proposed method.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2020, 68, 2; 307-315
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulation model and state analysis of ship transmission line
Autorzy:
Hu, Y.
Xu, M.
Li, Y.
Powiązania:
https://bibliotekanauki.pl/articles/259613.pdf
Data publikacji:
2018
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship power
transmission line
simulation model
insulation deterioration
Opis:
In order to discuss the simulation model of the ship transmission line and the state of the transmission line, an early fault model is built according to the evolution principle of the short circuit fault of the transmission line and combining with the fault characteristics of the early fault. A small distributed ship transmission line system is built in MATLAB/ Simulink. Then, combined with the constructed fault module, the original short circuit module, and the load module, the various states (normal state, early fault state, severe early fault state, short circuit state) of the ship transmission line are stimulated, and the features of voltage signal in each state is analysed. It is concluded that, due to the normal operation of the ship transmission line system, the variation characteristics of the flow signal and voltage signal caused by the sudden load mutation, that is, the sudden load and the sudden increase load, are very similar to the changes caused by the early fault. Therefore, in order to find a more accurate early fault detection method, the state is divided into normal state, sudden load state, sudden increase and sudden decrease load state.
Źródło:
Polish Maritime Research; 2018, S 3; 36-42
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Primary parametric resonance of an axially accelerating beam subjected to static loads
Autorzy:
Hu, Y.
Rong, Y.
Li, J.
Powiązania:
https://bibliotekanauki.pl/articles/949296.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
current-carrying beam
primary parametric resonance
magnetic field
axial movement
static loads
Opis:
Primary parametric resonance and stability of an axially accelerating and current-carrying beam subjected to static loads in magnetic field are investigated. The nonlinear magneto-elastic vibration equation is derived. The approximate solution of the static problem and the disturbance deferential equation of the beam with two sides simply supported are obtained. The frequency-response equation of primary parametric resonance is further achieved by a multi-scale method. According to stability conditions, the stability of the steady-state solution is also discussed. By numerical examples, the amplitude versus different parameter curves and the bifurcation diagrams of the amplitude are acquired. The effects of magnetic induction intensity, axial speed, detuning parameter and static loads on nonlinear vibration characteristics are also analyzed.
Źródło:
Journal of Theoretical and Applied Mechanics; 2018, 56, 3; 815-828
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An overview of design, control, power management, system stability and reliability in electric ships
Autorzy:
Ni, K.
Hu, Y.
Li, X.
Powiązania:
https://bibliotekanauki.pl/articles/1193412.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
electric ship
control algorithms
power electronics techniques
power drive system
stability
Opis:
With the fast development of power electronics techniques, electrification of shipboard power systems (SPS) is an unstoppable trend, and the concepts of electric ships (ESs) and all-electric ships (AESs) emerge. In order to meet the constantly increasing electricity demand in SPS, the medium voltage direct current (MVDC) SPS becomes a promising shipboard electrical network architecture. This paper aims to present a comprehensive review of the design, control, power management, system stability and reliability in ESs. The most recent technologies and academic achievements in these fields are discussed. In the near future, it is possible that the electric propulsion technology will be widely applied to various types of ships.
Źródło:
Power Electronics and Drives; 2017, 2, 37/2; 5-29
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new tritylodontid from the Upper Jurassic of Xinjiang, China
Autorzy:
Hu, Y
Meng, J.
Clark, J.M.
Powiązania:
https://bibliotekanauki.pl/articles/22519.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new tritylodontid
tritylodontid
Upper Jurassic
Jurassic
paleontology
Xinjiang
China
Tritylodontidae
Cynodontia
cynodont
Yuanotherium minor
Opis:
A new genus and species of Tritylodontidae, Yuanotherium minor, is described and compared with other known tritylodontids. The new taxon is represented by a partially preserved upper jaw with three postcanines, collected from the upper part of the Shishugou Formation (Oxfordian, Late Jurassic) in the Wucaiwan area of the Junggar Basin, northwestern Xinjiang, China. Like other tritylodontids its maxillary teeth have three rows of blade−like trenchant cusps separated by deep furrows. The new species differs from other tritylodontids mainly in having posteriormost two cusps of the median row on upper postcanines closely placed. The new tritylodontid may have been omnivorous rather than herbivorous, as previously suggested for tritylodontids in general.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 3; 385-391
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pleistocene Equid Brain Endocast from Shanxi Province, China
Autorzy:
Hu, Y.
Chen, Y.
Wang, S.
Sun, Q.
Powiązania:
https://bibliotekanauki.pl/articles/946031.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mammalia
equus
equid brain
pleistocene
shanxi province
china
Opis:
Brain endocasts are rare in the fossil record because they are only preserved under exceptional conditions. An equid brain endocast from the early Pleistocene of Wanrong County, Shanxi Province, China, is reported in this paper. Measuring approximately 140 × 95.2 × 83 mm, the new specimen represents a relatively advanced adult horse brain. Comparisons indicate that it is more derived than those of Hyracotherium and Mesohippus in having an expanded neocortex, and more than those of Pliohippus and Hipparion in having an enlarged network of branching sulci; in most characters involving these sulci, the Shanxi brain conforms to the extant species Equus caballus. The sulcus diagonalis of the Equus brain appears to have evolved conservatively during the early Pleistocene, whereas the sulcus suprasylvius seems to have evolved rapidly. The specimen demonstrates that the development of a high degree of complexity predates the enlargement of the brain in the horse, which increased in length, breadth, and especially height during the late Cenozoic.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 2; 253-258
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
System Design for Evenness Measurement of Raw Silk
Projekt systemu do pomiaru równomierności surowego jedwabiu
Autorzy:
Pan, Q.
Chen, M.
Hu, Y.
Zuo, B.
Powiązania:
https://bibliotekanauki.pl/articles/232659.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
image vision
raw silk evenness
diameter extraction
variation coefficient
CV
system verification
analiza obrazu
jedwab surowy
równomierność jedwabiu
współczynnik zmienności
systemy kontroli
Opis:
The evenness of raw silk is one of its most valuable qualities. Seriplane inspection is a common test for raw silk evenness but is prone to human error and lacks accurate repeatability; the Uster evenness tester is another common approach but is costly and vulnerable to environmental factors. An image-based raw silk evenness detection system is proposed in this paper. The system is comprised of an image acquisition segment with a CCD image sensor, telecentric lens, light source, over feeding device, and raw silk winding device, plus an image processing segment tasked with threshold segmentation and morphology operations. Images of the raw silk are first captured with the image acquisition segment, then the images are processed by threshold segmentation and morphology processing; the diameters obtained in this segment are then used to calculate the variation coefficient (CV), which characterises the evenness of the raw silk. We conducted three experiments to test the stability, repeatability, and accuracy of the system. The results showed that the system proposed is stable, repeatable, and accurate.
Równomierność surowego jedwabiu jest jedną z jego najcenniejszych zalet. Dotychczas powszechnie stosowane systemy kontroli równomierności jedwabiu są podatne na błąd człowieka i nie mają dokładnej powtarzalności, są kosztowne i wrażliwe na czynniki środowiskowe. W artykule zaproponowano system oceny równomierności jedwabiu oparty na analizie obrazu. Zaproponowany system składa się z segmentu akwizycji obrazu z przetwornikiem obrazu CCD, soczewką telecentryczną, źródłem światła, urządzeniem nadawczym i urządzeniem do nawijania surowego jedwabiu oraz segmentu przetwarzania obrazu, którego zadaniem jest progowa segmentacja i operacje morfologiczne. Obrazy surowego jedwabiu są najpierw przechwytywane przez segment pozyskiwania obrazu, następnie obrazy są przetwarzane przez segmentację progową i przetwarzanie morfologiczne; średnice uzyskane w tym segmencie są następnie wykorzystywane do obliczenia współczynnika zmienności (CV), który charakteryzuje równomierność surowego jedwabiu. Analiza otrzymanych wyników pokazała, że zaproponowany system jest stabilny, powtarzalny i dokładny.
Źródło:
Fibres & Textiles in Eastern Europe; 2018, 1 (127); 21-24
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New dinosaur egg material from Yunxian, Hubei Province, China resolves the classification of dendroolithid eggs
Autorzy:
Zhang, S.
Yang, T.-R.
Li, Z.
Hu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/21925.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Opis:
The oofamily Dendroolithidae is a distinct group of dinosaur eggs reported from China and Mongolia, which is characterized by branched eggshell units and irregular pore canals. The ootaxonomic inferences, however, were rarely discussed until now. A colonial nesting site was recently uncovered from the Qinglongshan region, Yunxian, Hubei Province, China. More than 30 dendroolithid egg clutches outcrop on the Tumiaoling Hill, including an extremely gigantic clutch containing 77 eggs. All clutches were exposed in the Upper Cretaceous fluvial-deposited Gaogou For mation. In this study, we emend the diagnosis of the oogenus Placoolithus and assign all dendroolithid eggs from the Tumiaoling Hill to a newly emended oospecies Placoolithus tumiaolingensis that shows greatly variable eggshell microstructure. Moreover, our study also disentangles the previous vexing classification of dendroolithid eggs. We conclude that Dendroolithus tumiaolingensis, D. hongzhaiziensis, and Paradendroolithus qinglongshanensis, all of which were previously reported from Yunxian, should be assigned to the newly emended oospecies Placoolithus tumiaolingensis.
Źródło:
Acta Palaeontologica Polonica; 2018, 63, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Infuence of Iron Ion on Thermal Behavior of Ammonium Nitrate and Emulsion Explosives
Autorzy:
Xu, Z.
Liu, D.
Hu, Y.
Ye, Z.
Wei, Y.
Powiązania:
https://bibliotekanauki.pl/articles/357932.pdf
Data publikacji:
2010
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
Accelerating Rate Calorimeter (ARC)
ammonium nitrate
critical temperature
emulsion explosives
thermal stability
Opis:
The infuence of ferric nitrate on the thermal stability of ammonium nitrate and emulsion matrix were used to study with Accelerating Rate Calorimeter (ARC) and constant temperature thermal decomposition experiment in this paper. It is shown that ferric nitrate has signifcant catalytic property to the ammonium nitrate and emulsion matrix, which decrease the initial decomposition temperature of ammonium nitrate by 60.16 C and emulsion matrix by 30.33 C. The results of the infuence of ferric nitrate on catalysis of ammonium nitrate using ARC and constant temperature thermal decomposition experiment are the same. The most probable mechanism function, activation energy and the preexponential factor of ammonium nitrate with ferric nitrate were determined to be f(α) = 1-α, E = 195.41 kJ/mol, A = 2.08×1019 s-1. The kinetics of ammonium nitrate decomposition can be used to calculate the critical temperatures for ammonium nitrate decomposition with and without the presence of ferric nitrate, based on the Frank-Kamenetskii model of thermal explosion. Furthermore, as the iron-plate experiment shows, ferric nitrate can signifcantly reduce the critical temperature of emulsion matrix decomposition. Once the ferric nitrate interfuses in the ammonium nitrate and emulsion matrix, the thermal stability of ammonium nitrate and emulsion matrix is decreasing.
Źródło:
Central European Journal of Energetic Materials; 2010, 7, 1; 77-93
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Estimation of wind erosion rates of Mongolian Plateau by using 137Cs tracing technique
Ocena intensywnosci erozji eolicznej Plaskowyzu Mongolskiego z wykorzystaniem techniki oznaczania 137Cs
Autorzy:
Qi, Y
Liu, J.
Shi, H.
Zhuang, D.
Hu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/81677.pdf
Data publikacji:
2010
Wydawca:
Szkoła Główna Gospodarstwa Wiejskiego w Warszawie. Wydawnictwo Szkoły Głównej Gospodarstwa Wiejskiego w Warszawie
Tematy:
estimation
wind erosion
erosion rate
Mongolian Plateau
137Cs tracing technique
Opis:
Wind erosion is one of the major environmental problems in semi-arid and arid regions. Here we established a transect from northwest (Tariat, Mongolia) to southeast (Xilingol, Inner Mongolia of China) across the Mongolian Plateau, and selected eight sampling sites along the transect. We then estimated the soil wind erosion rates by using the 137Cs tracing technique and examined their spatial dynamics. In the Mongolia section (from Tariat to Sainshand), the wind erosion rate increased gradually with vegetation type and climatic regimes; the wind erosion process was controlled by physical factors such as annual precipitation and vegetation coverage, etc. While in the China section (Inner Mongolia), the wind erosion rates of Xilinhot, Zhengxiangbai Banner and Taipusi Banner were thrice as much as those of Bayannur of Mongolia, although these four sites were all dominated by typical steppe. Besides the physical factors, higher population density and livestock carrying level should be responsible for the higher wind erosion rates in these regions of Inner Mongolia.
W pracy przedstawiono wyniki badań intensywności erozji eolicznej Płaskowyżu Mongolskiego, określonej na podstawie ośmiu prób gruntu pobranego wzdłuż transektu o długości około 1400 km, przebiegającego przez teren Mongolii i Chin. Do oceny intensywności erozji wykorzystano technikę oznaczania 137Cs w wierzchnich warstwach gruntu do głębokości 30 cm. Stwierdzono, że intensywność erozji w analizowanym transekcie od północnego-zachodu stopniowo wzrasta wraz ze zmianami reżimu klimatycznego (zmniejszania się rocznej wysokości opadów), a także zmianami pokrycia roślinnego. Chińska część Płaskowyżu o charakterze stepowym jest trzykrotnie bardziej intensywnie erodowana. Oprócz czynników fizycznych, na intensywność procesu erozji eolicznej wpływa większa gęstość zaludnienia Płaskowyżu na terenie Chin, a także większe pogłowie zwierząt hodowlanych.
Źródło:
Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation; 2010, 42, 1; 197-208
0208-5771
Pojawia się w:
Annals of Warsaw University of Life Sciences - SGGW. Land Reclamation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on pre-concentration efficiency of wolframite from tungsten ore using gravity and magnetic separations
Autorzy:
Lu, D.
Wang, Y.
Jiang, T.
Sun, W.
Hu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/109597.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
tungsten ore
pre-concentration
separation efficiency
gravity separation
magnetic separation
Opis:
Pre-concentration is effectively applied in recovering wolframite from tungsten ore, due to its benefits of further upgrading tungsten ore and improving separation efficiency. The most important pre-concentration techniques for tungsten ore include gravity separation and magnetic separation, based on the fact that there are appreciable differences, between the desired wolframite and the gangue minerals, in density and magnetic susceptibility. This study investigated the separation efficiency of gravity pre-concentration (Falcon Concentrator) and high-gradient magnetic pre-concentration (SLon VPHGMS) for the beneficiation of a Canada tungsten ore. It is a low-grade type of ore with high silica and arsenic content, and an average content of WO3 is about 0.45%. The optimum conditions for different operational parameters of two pre-concentration separators were studied on this low-grade material. The results presented in this paper suggested that although both pre-concentration techniques were effective for producing pre-concentrates containing high WO3, magnetic pre-concentration showed significantly better separation efficiency. Over 90% of the feed was rejected as the final tailings, meanwhile, over 85% of arsenic minerals were removed with tailings, while the WO3 loss was less than 15%.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 2; 718-728
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mining file repository accesses for detecting data exfiltration activities
Autorzy:
Hu, Y.
Frank, C.
Walden, J.
Crawford, E.
Kasturiratna, D.
Powiązania:
https://bibliotekanauki.pl/articles/91636.pdf
Data publikacji:
2012
Wydawca:
Społeczna Akademia Nauk w Łodzi. Polskie Towarzystwo Sieci Neuronowych
Tematy:
data exfiltration
file repository
KDE
Opis:
Studies show that a significant number of employees steal data when changing jobs. Insider attackers who have the authorization to access the best-kept secrets of organizations pose a great challenge for organizational security. Although increasing efforts have been spent on identifying insider attacks, little research concentrates on detecting data exfiltration activities. This paper proposes a model for identifying data exfiltration activities by insiders. It measures the concentration of file repository access data for finding certain suspicious activities. It also uses statistical methods to profile legitimate uses of file repositories by authorized users. By analyzing legitimate file repository access logs, user access profiles are created and can be employed to detect a large set of data exfiltration activities. The effectiveness of the proposed model was tested with file access histories from the subversion logs of the popular open source project KDE.
Źródło:
Journal of Artificial Intelligence and Soft Computing Research; 2012, 2, 1; 31-41
2083-2567
2449-6499
Pojawia się w:
Journal of Artificial Intelligence and Soft Computing Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reverse flotation of ultrafine magnetic concentrate by using mixed anionic/cationic collectors
Autorzy:
Lu, D.
Hu, Y.
Li, Y.
Jiang, T.
Sun, W.
Wang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/110550.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
ultrafine magnetite
collector mixture
reverse flotation
closed flotation
Opis:
Compared to reverse cationic flotation, the advantages of reverse anionic flotation include relatively lower sensitivity to slimes and lower reagent cost. Besides, anionic collectors were found to have excellent capability of selectively separating an ultrafine magnetite ore. Addition of a small amount of cationic collector into the anionic collector as the collector mixture can improve the metallurgical results of removing silicates in reverse flotation. In this paper, NaOL and DDA were used for reverse flotation of the ultrafine magnetic concentrate. The separation performance of the collector mixture was investigated at different ratios of NaOL and DDA. The results showed that a better separation performance was obtained for the collector mixture than for NaOL alone. There was an optimal molar ratio between NaOL and DDA equal to 10:1. In the flotation system with the presence of the collector mixture, the good selectivity was found when starch was used as a depressor for magnetite and CaO was used as an activator for quartz. The influences of starch and CaO dosages on the separation performance of magnetite, quartz and chlorite had been investigated through micro-flotation tests. The infrared spectral analysis showed stretching vibration peaks of chemical adsorption of the collector mixture on the magnetite surface. The peaks were not present when starch was used as the depressor for magnetite. The closed flotation tests on the magnetic concentrate with the particle size of -25 μm were performed in the laboratory. The Fe concentrate assaying 64.52 % was obtained with Fe recovery of 80.66%, for the Fe content of feed equal to 52.98%.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 724-736
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of polyacrylic acid on the surface properties of calcite and fluorite aiming at their selective flotation
Autorzy:
Zhang, C.
Gao, Z.
Hu, Y.
Sun, W.
Tang, H.
Yin, Z.
He, J.
Guan, Q.
Zhu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/110577.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
calcite
fluorite
selective flotation
polyacrylic acid
Opis:
In this study, the polyacrylic acid (PAA) was studied as a selective depressant for calcite in the selective flotation of fluorite and calcite, and the implications of this process for the separation of fluorite ore were studied using micro-flotation tests, and the results were analyzed with Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) analyses. The flotation tests indicated that the preferential adsorption of PAA onto calcite rather than sodium oleate (NaOl) could selectively depress the flotation of calcite, allowing its separation from fluorite at pH 7. The zeta potential of calcite became more negative with the addition of PAA rather than with NaOl. However, the characteristic features of PAA adsorption were not observed for fluorite, suggesting that NaOl preferentially adsorbed on the surface of fluorite, or that PAA could be replaced by NaOl on the fluorite surface. FT-IR and XPS analysis were utilized to obtain a better understanding of the mechanism by which PAA was more strongly adsorbed on the calcite surface than NaOl. This was revealed to occur through chemical bonding between the carboxyl group of PAA and the hydroxyl groups of the Ca species on the calcite surface, modifying the structure of the adsorbed layer. A possible adsorption mechanism, along with a postulated adsorption mode for the surface interaction between PAA and calcite, is proposed.
Źródło:
Physicochemical Problems of Mineral Processing; 2018, 54, 3; 868-877
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 76

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