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Tytuł:
Modeling and Identification Method of Bolt Loosening of Joint Surface under Axial Tension of Multistage Disk-Drum Rotor
Autorzy:
Yue, Cong
Zheng, Xiangmin
Wang, Chaoge
Liu, Hao
Chen, Hu
Powiązania:
https://bibliotekanauki.pl/articles/24200822.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
multistage drum rotor
bolt loosening
equivalent joint stiffness
structural health monitoring
Opis:
Individual bolt at key connection positions is prone to loose when the engine is cycle-operating under complex loads. A joint surface equivalent stiffness model is derived and developed based on the connection characteristics of bolt screwing in the multi-exciting environment of the high-pressure rotor. The model is used to analyse the effect of bolt missing at circumferential positions with the equivalent stiffness loss. Vibration experiments under both axial force and lateral impact were carried out to obtain the dynamic response feature of the multistage disk-drum simulated rotor with missing one bolt at different positions. The Spearman correlation coefficient was applied to evaluate the identification effect of different measuring points on the bolt loosening position. The study shows that the eigenfrequencies of experimental results have a consistent trend with the equivalent stiffness variation caused by single bolt missing model. This method also provides a theoretical basis for the detection of bolt deviation position with multi-exciting vibration detection.
Źródło:
Eksploatacja i Niezawodność; 2023, 25, 2; art. no. 165779
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coated NPK Fertilizer Based on Citric Acid-Crosslinked Chitosan/Alginate Encapsulant
Autorzy:
Mesias, Vince St. D.
Agu, Anne Bernadette S.
Benablo, Precious Japheth L.
Chen, Chun-Hu
Penaloza Jr., David P.
Powiązania:
https://bibliotekanauki.pl/articles/124714.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
controlled release
crosslinking
encapsulation
NPK fertilizer
Opis:
A coated nitrogen-phosphorus-potassium (NPK) fertilizer was prepared via crosslinking chitosan and alginate using citric acid. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), particle size analysis, and zeta potential measurement showed the successful crosslinking, appropriate size, and colloidal stability of the coated NPK fertilizer. The encapsulation capability of the crosslinked chitosan/alginate (Chi/Alg) was studied using fluorescence spectroscopy and NPK analysis. The release behavior studies under various pH conditions showed that Chi/Alg NPK conformed to the standards of controlled release fertilizer with a maximum release rate of 40% for 30 days. The investigation of the release mechanism using Korsemeyer-Peppas mathematical model showed that the release of nutrients is governed by both coating material relaxation and diffusion process.
Źródło:
Journal of Ecological Engineering; 2019, 20, 11; 1-12
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fault risk assessment of underwater vehicle steering system based on virtual prototyping and Monte Carlo simulation
Autorzy:
He, D.
Hu, N.
Hu, L.
Chen, L.
Guo, Y.
Chen, S.
Powiązania:
https://bibliotekanauki.pl/articles/260342.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
fault risk assessment
underwater vehicle
virtual prototyping
Monte Carlo simulation
steering system
fault simulation
Opis:
Assessing the risks of steering system faults in underwater vehicles is a human-machine-environment (HME) systematic safety field that studies faults in the steering system itself, the driver’s human reliability (HR) and various environmental conditions. This paper proposed a fault risk assessment method for an underwater vehicle steering system based on virtual prototyping and Monte Carlo simulation. A virtual steering system prototype was established and validated to rectify a lack of historic fault data. Fault injection and simulation were conducted to acquire fault simulation data. A Monte Carlo simulation was adopted that integrated randomness due to the human operator and environment. Randomness and uncertainty of the human, machine and environment were integrated in the method to obtain a probabilistic risk indicator. To verify the proposed method, a case of stuck rudder fault (SRF) risk assessment was studied. This method may provide a novel solution for fault risk assessment of a vehicle or other general HME system.
Źródło:
Polish Maritime Research; 2016, 3; 97-105
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of water flows on ship traffic in narrow water channels based on cellular automata
Autorzy:
Hu, H.
Chen, X.
Sun, Z.
Powiązania:
https://bibliotekanauki.pl/articles/260068.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
narrow channel
cellular automata
simulation
ship interaction
Opis:
In narrow water channels, ship traffic may be affected by water flows and ship interactions. Studying their effects can help maritime authorities to establish appropriate management strategies. In this study, a two-lane cellular automation model is proposed. Further, the behavior of ship traffic is analyzed by setting different water flow velocities and considering ship interactions. Numerical experiment results show that the ship traffic density-flux relation is significantly different from the results obtained by classical models. Furthermore, due to ship interactions, the ship lane-change rate is influenced by the water flow to a certain degree.
Źródło:
Polish Maritime Research; 2017, S 3; 130-135
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bifurcation and control for a discrete-time prey–predator model with Holling-IV functional response
Autorzy:
Chen, Q.
Teng, Z.
Hu, Z.
Powiązania:
https://bibliotekanauki.pl/articles/907649.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
discrete prey predator model
flip bifurcation
Hopf bifurcation
saddle node bifurcation
OGY chaotic control
bifurkacja Hopfa
sterowanie chaosem
Opis:
The dynamics of a discrete-time predator–prey model with Holling-IV functional response are investigated. It is shown that the model undergoes a flip bifurcation, a Hopf bifurcation and a saddle-node bifurcation by using the center manifold theorem and bifurcation theory. Numerical simulations not only exhibit our results with the theoretical analysis, but also show the complex dynamical behaviors, such as the period-3, 6, 9, 12, 20, 63, 70, 112 orbits, a cascade of period-doubling bifurcations in period-2, 4, 8, 16, quasi-periodic orbits, an attracting invariant circle, an inverse period-doubling bifurcation from the period-32 orbit leading to chaos and a boundary crisis, a sudden onset of chaos and a sudden disappearance of the chaotic dynamics, attracting chaotic sets and non-attracting sets. We also observe that when the prey is in chaotic dynamics the predator can tend to extinction or to a stable equilibrium. Specifically, we stabilize the chaotic orbits at an unstable fixed point by using OGY chaotic control.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2013, 23, 2; 247-261
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Motion characteristics after ricochet: an experimental investigation
Autorzy:
Chen, Guoming
Hu, Junhua
Liu, An
Feng, Jinfu
Hu, Qingqing
Powiązania:
https://bibliotekanauki.pl/articles/260197.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
air-water trans-media vehicle (AWTMV)
ricochet
nose
initial conditions
responses
Opis:
The ricochet behaviour of the air–water trans-media vehicle (AWTMV) during water-entry crossing was experimentally investigated. Three types of small-scale AWTMV including cone, ogive, and flat nose were used in the test. The underwater trajectory, velocity, and inclination angle of projectiles during the ricochet process were obtained using a high-speed camera. The angle change of the AWTMV and the ratio of the residual velocity are introduced. Based on this result, the relationship between the ricochet responses and initial conditions was derived. The results of this study show that (1) a small incident angle and great velocity make the occurrence of ricochet behaviour easier, (2) the stability of the trajectory of projectiles with cone, ogive, and flat nose weakened in turn at the same initial conditions, (3) the angle change and the ratio of the residual velocity are linear functions of the incident angle and velocity.
Źródło:
Polish Maritime Research; 2020, 2; 4-10
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tight focusing of radially polarized beams by a devil’s vortex lens
Autorzy:
Chen, Z.
Hu, X.
Chen, X.
Wang, X.
Pu, J.
Powiązania:
https://bibliotekanauki.pl/articles/173576.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
devil’s vortex lens
radially polarized beam
tight focusing
high numerical aperture
Opis:
Tight focusing of radially polarized beams with a devil’s vortex lens is numerically investigated. Multiple focal spots can be generated in the geometric focus when a radially polarized beam is focused by a high numerical aperture objective in the presence of a devil’s vortex lens. The position of the major focal spot shifts from the geometric focus when a devil’s vortex lens with S = 1 is employed, and the position of the focal spot can be controlled by the numerical aperture of the objective. The intensity components of the major focal spot are influenced by the vortex phase of the devil’s vortex lens. A strong longitudinal component near the optical axis is produced by a devil’s vortex lens without vortex phase, and a nearly pure transversal field is produced by a devil’s vortex lens with vortex phase.
Źródło:
Optica Applicata; 2018, 48, 3; 389-398
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
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:
Uniaxial compression test and numerical simulation of rock-like specimen with T-Shaped cracks
Autorzy:
Liangxiao, Xiong
Chen, Haijun
Xu, Zhongyuan
Hu, Deye
Powiązania:
https://bibliotekanauki.pl/articles/27312090.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
skała sztuczna
pęknięcie
kształt T
próba
badanie ściskania jednoosiowego
symulacja numeryczna
artificial rock
T-shaped crack
uniaxial compression test
numerical simulation
Opis:
In this study, the uniaxial compression test and PFC2D numerical simulation were carried out on the artificial rock specimen with T-shaped prefabricated fractures. The effects of the lengths l1, l2 of the main fractures, the length l3 of the secondary fracture, and the angle β between the secondary fracture and the loading direction on the uniaxial compressive strength and crack evolution law of specimen were studied. The research results show that the change of l1, l2 and β has obvious effect on the compressive strength and crack growth of the specimen, but the change of l3 has little effect on the compressive strength of the specimen. When l3 = 40 mm and l1 ≠ l2, the angle β influences on the crack propagation and failure mode of the specimen.
Źródło:
Archives of Civil Engineering; 2023, 69, 2; 227--244
1230-2945
Pojawia się w:
Archives of Civil Engineering
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:
Iterative estimators of parameters in linear models with partially variant coefficients
Autorzy:
Hu, S.
Meinke, K.
Chen, R.
Huajiang, O.
Powiązania:
https://bibliotekanauki.pl/articles/929607.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
model liniowy
estymacja parametrów
algorytm iteracyjny
współczynnik zmienności
linear model
parameter estimation
iterative algorithms
variant coefficients
Opis:
A new kind of linear model with partially variant coefficients is proposed and a series of iterative algorithms are introduced and verified. The new generalized linear model includes the ordinary linear regression model as a special case. The iterative algorithms efficiently overcome some difficulties in computation with multidimensional inputs and incessantly appending parameters. An important application is described at the end of this article, which shows that this new model is reasonable and applicable in practical fields.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2007, 17, 2; 179-187
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of the fixed carbon and ash in blast furnace dust on its co-reduction with seaside titanomagnetite
Autorzy:
Wang, Xiaoping
Hu, Tianyang
Chen, Chuanzhong
Sun, Tichang
Powiązania:
https://bibliotekanauki.pl/articles/109936.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
seaside titanomagnetite
blast furnace dust
co-reduction roasting
fixed carbon
ash
Opis:
Previous research has found that the fixed carbon in blast furnace dust (BFD) could be used as the reductant of co-reduction roasting of the iron oxides in seaside titanomagnetite and BFD to replace coals. This research studied the influence mechanism of the fixed carbon and ash in BFD on coreduction.Results showed that both fixed carbon and ash in BFD promoted the reduction of iron, while ash had adverse effect on separation of titanium and iron. The main mechanism was as follows: The ash in BFD accelerated melting. In addition, the iron oxide in the ash of BFD could be reduced to metallic iron cores more easily in the initial stage, providing the site of inhomogeneous core and promoting the aggregation and growth of metallic iron. Furthermore, the fixed carbon mainly reacted with iron ore by solid-solid reaction, leading to a rapid reduction rate and a high utilization rate of fixed carbon.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 5; 1323-1337
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Social Impacts on the Maritime Education – a Case Study of National Kaohsiung Marine University in Taiwan
Autorzy:
Hu, Jia-Shen
Chang, S. W.
Chen, T. S.
Powiązania:
https://bibliotekanauki.pl/articles/116312.pdf
Data publikacji:
2008
Wydawca:
Uniwersytet Morski w Gdyni. Wydział Nawigacyjny
Tematy:
Maritime Education and Tr
Maritime Education
human resources
Shipping Industry
educational reform
STCW-95
Quality Assurance
Opis:
Recent developments in Taiwan toward the technology intensive country, the employment of cost effective foreign labors by shipping companies, the widespread of universities and the internationalization of shipping industries propose considerable threats on the quality assurance of maritime education. A resultant crisis for lacking on-board seafarers with managerial levels has urged the consolidation of governmental, private and educational organizations in the attempts to further improve the quality of maritime education and to promote the on-board career incentives. The process from the formulation of problems to the implementation of strategies undertaken by the National Kaohsiung Marine University (NKMU) is reviewed. A chain reaction initiated from the degradation of students’ entry performances due to the widespread of universities has formed a viscous cycle leading to the outsourcing of foreign human resources by shipping industry. Strategies in the aspects of course reform, joint ventures of lectureship with shipping industry, pre-courses for students’ extended career plans and the establishment of educational center that consolidates the departments of navigation, marine engineering and fishery in NKMU are illustrated.
Źródło:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation; 2008, 2, 2; 197-203
2083-6473
2083-6481
Pojawia się w:
TransNav : International Journal on Marine Navigation and Safety of Sea Transportation
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Stitch Structure on the Reading Performance of Fabric-Based Embroidered UHF RFID Tags
Wpływ struktury ściegu na wydajność odczytu haftowanych etykiet RFID UHF
Autorzy:
Xudong, Yang
Yingxue, Chen
Tingting, Wang
Yong, Zhang
Jiyong, Hu
Powiązania:
https://bibliotekanauki.pl/articles/1419756.pdf
Data publikacji:
2021
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
embroidery
stitch structure
RFID
Radio Frequency Identification
conductive yarn
antenna
haft
struktura ściegu
identyfikacja radiowa
przędza przewodząca
antena
Opis:
As the demand for low-cost rapid preparation techniques for RFID (Radio Frequency Identification) fabric tags is increasing, embroidery technologists have attempted to fabricate tag antennas. However, the effects of stitch structures on the performance of tag antennas have rarely been studied. Since the structure of an embroidered stitch is related to the embroidering process parameters and embroidery thread, this study chose a common stitch trace type to prepare two sets of UHF RFID tag antennae by changing the embroidery thread structure and stitch length, and then the electrical and gain properties of these antennas were analyzed. And again, the reading performance of the corresponding tag was evaluated. The results showed that the antennas embroidered with copper/PET wrapped yarns have higher energy transfer efficiency than those with single copper wire yarns. When the stitch length increases from 0.9 to 5 mm, the read range of the embroidered tag firstly increases and then decreases, due to the large embroidering process deviation of the tag antenna geometry, and the optimal stitch length for the read range is 1.7 mm, where the read range is 12.95 m. When the stitch length is 5 mm, the read range is minimum – 9.56 m. In summary, this study determined the embroidered thread structure and the process design of the stitch length in terms of the performance of a fabric-based embroidery antenna for an RFID tag as well as the read range.
Wraz ze wzrostem zapotrzebowania na niedrogie techniki szybkiego przygotowania etykiet materiałowych RFID (identyfikacja radiowa), technolodzy haftu podjęli próbę wyprodukowania specjalnych etykiet. Dotychczas rzadko badano wpływ struktur ściegowych na działanie etykiet antenowych. Ponieważ struktura haftowanego ściegu jest powiązana z parametrami procesu i nicią zastosowaną do haftu, w badaniu przeanalizowano ścieg typowy. Przygotowano dwa zestawy antenowych etykiet RFID UHF różniących się strukturą nici do haftu i długością ściegu, a następnie przeanalizowano właściwości wzmocnienia tych anten. Wyniki pokazały, że anteny haftowane przędzą owiniętą miedzią/PET mają wyższą efektywność przenoszenia energii, niż anteny z pojedynczą przędzą z drutu miedzianego. Gdy długość ściegu wzrośnie z 0,9 do 5 mm, zasięg odczytu haftowanej przywieszki najpierw rośnie, a następnie maleje, ze względu na duże odchylenie procesu haftowania geometrii anteny przywieszki, a optymalna długość ściegu dla zakresu odczytu wynosi 1,7 mm, gdzie zasięg odczytu wynosi 12,95 m. Gdy długość ściegu wynosi 5 mm, zasięg odczytu wynosi minimum – 9,56 m. Podsumowując, w badaniu określono strukturę haftowanej nici i projekt długości ściegu pod kątem wydajności anteny, a także zasięgu odczytu.
Źródło:
Fibres & Textiles in Eastern Europe; 2021, 2 (146); 48-53
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Probability mapping of petroleum occurrence with a multivariate-Bayesian approach for risk reduction in exploration, Nanpu Sag of Bohay Bay Basin, China
Autorzy:
Hu, Suyun
Guo, Qiulin
Chen, Zhuoheng
Mi, Shiyun
Xie, Hongbin
Powiązania:
https://bibliotekanauki.pl/articles/94428.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
oil exploration
risk visualization
well planning
Nanpu Sag
probability map
poszukiwanie ropy naftowej
wizualizacja ryzyka
mapa prawdopodobieństwa
Opis:
A multivariate-Bayesian approach has been applied to the Nanpu Sag of the Bohai Bay Basin, eastern China, to evaluate probability of oil occurrence. The geological data from 343 exploratory wells and seismic interpretations that were available at the end of 2004 were used for the purpose. Seventeen wells were drilled after the evaluation in 2005, sixteen of which reached their target horizon. Eight of the nine wells drilled in areas with a predicted high probability of hydrocarbon occurrence (>50%) encountered commercial oil, indeed; post-drilling analysis indicated that seven of these eight wells yielded high flow rates from thick net pay, and that one of these wells yielded a low flow rate. Seven wells were drilled in areas with a predicted relatively low probability (<50%) of oil occurrence; three of them were dry and four recovered oil with relatively low flow rates. Comparison of the post-drilling results with the pre-drilling prediction suggests that the multivariate-Bayesian approach can help visualize geological risk, thus improving exploration success by optimizing the drilling strategy.
Źródło:
Geologos; 2009, 15, 2; 91-102
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study on biaxial dynamical compressive test and PFC2D numerical simulation of artificial rock sample with single joint
Autorzy:
Liangxiao, Xiong
Chen, Haijun
Gao, Xinghong
Xu, Zhongyuan
Hu, Deye
Powiązania:
https://bibliotekanauki.pl/articles/2203424.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Dynamic biaxial compression tests and Particle Flow Code numerical simulations of the cement mortar specimens with a single joint were carried out to study the mechanical properties and crack evolution of artificial rock samples with a single joint. The effects of lateral stress σ2, loading rate V, the dip angle β (between the vertical loading direction and the joint) on the biaxial compressive strength σb, and the evolution law of crack were investigated. Test results showed that; (1) when both the dip angle β and the loading rate V remained unchanged, the biaxial compressive strength σb increased with the increase in the lateral stress σ2, while σ2 had no obvious effect on the crack evolution law; (2) when both the dip angle β and the lateral stress σ2 were kept unchanged, the loading rate V had an insignificant effect on the biaxial compressive strength σb and the crack evolution law; (3) when both the lateral stress σ2 and the loading rate V were constant, the biaxial compressive strength σb decreased first and then increased with the increase in the dip angle β; however, the dip angle β did not significantly affect the crack evolution law. The conclusions obtained in this paper are presented for the first time.
Źródło:
Archives of Civil Engineering; 2023, 69, 1; 213--229
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A numerical approach to predict the rotating stall in the vaneless diffuser of a centrifugal compressor using the eigenvalue method
Autorzy:
Hu, C.
Liu, P.
Zhu, X.
Chen, H.
Du, Z.
Powiązania:
https://bibliotekanauki.pl/articles/281006.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
instability
vaneless diffuser
eigenvalue problem
spectral method
Opis:
A two-dimensional incompressible flow model is presented to study the occurrence of rotating stall in vaneless diffusers of centrifugal compressors. The diffuser considered has two parallel walls, and the undisturbed flow is assumed to be circumferentially uniform, isentropic, and to have no axial velocity. The linearized 2D Euler equations for an incompressible flow in a fixed frame of the coordinate system are considered. After discretization by a spectral collocation method based on Chebyshev-Gauss-Lobatto points, the generalized eigenvalue problem is solved through the QZ algorithm. The compressor stability is judged by the imaginary part of the eigenvalue obtained. Based on the 2D stability analysis, the influence of inflow angle, radius ratio and wave number are studied. The results from the present stability analysis are compared with some experimental measurement and Shen’s model. It is showed that diffuser instability increases rapidly and the stall rotational speed decreases quickly with an increase in the diffuser radius ratio. The largest critical inflow angle can be obtained when the wave number is around 3 ∼ 5 for the radius ratio between 1.5 to 2.2. It is also verified that the stability model proposed in this paper agrees well with experimental data and has the capability to predict the onset of rotating stall, especially for wide diffusers.
Źródło:
Journal of Theoretical and Applied Mechanics; 2017, 55, 2; 635-647
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reliability assessment for micro inertial measurement unit based on accelerated degradation data and copula theory
Autorzy:
Chi, Bingjia
Wang, Yashun
Hu, Jingwen
Zhang, Shufeng
Chen, Xun
Powiązania:
https://bibliotekanauki.pl/articles/2173134.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
MIMU
Wiener process
accelerated degradation test
copula
reliability assessment
Opis:
With its extensive use in industry, assessing the reliability of the micro inertial measurment unit (MIMU) has become a pressing need. Unfortunately, the MIMU is made up of several components, and the degradation processes of each are intertwined, making it difficult to assess the MIMU’s reliability and remaining useful life. In this research, we offer a reliability assessment approach for the MIMU, which has long-lifetime and multiple performance characteristics (PCs), based on accelerated degradation data and copula theory.Each PC model of MIMU is constructed utilizing drift Brownian motion to depict accelerated degradation process. The copula function is used to model the multivariate dependent accelerated degradation test data and to describe the dependency between multiple MIMU performance parameters. The particle swarm optimization algorithm is used to estimate the unknown parameters in the multi-dependent ADT model. Finally, the storage test and simulation example on MIMU’s accelerated degradation data verify the feasibility and effectiveness of the proposed method.
Źródło:
Eksploatacja i Niezawodność; 2022, 24, 3; 554--563
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beneficiation of Ga from alunite concentrates by selective acid leaching and alkaline precipitation
Autorzy:
Zhu, Mao-Lan
Chen, Hang
Zhong, Shui-Ping
Huang, Zhong-Sheng
Chen, Xi
Hu, Zhi-Biao
Powiązania:
https://bibliotekanauki.pl/articles/110733.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
gallium
selective leaching
precipitation
alunite concentrate
Opis:
In this study beneficiation of Ga from alunite ore was investigated. The effects of the calcination temperature, H2SO4 concentration, leaching temperature and liquid-solid ratio on the dissolution characteristic of Ga, K and Al were studied. The results showed that increasing the calcination temperature, H2SO4 concentration and leaching temperature can improve the solubility of K and Al. However, higher H2SO4 concentration and lower leaching temperature can improve the dissolution of Ga, which was beneficial to recovery of Ga. On the basis of the solubility difference in H2SO4, a two-stage process of selective acid leaching and alkali precipitation of Ga was proposed. The concentration of Ga was increased significantly from 54 g/t in alunite ore to 4100 g/t in alkali precipitation product. The major elements of Al and K in alunite were recovered as the alum crystal with a purity of 99.62%.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 4; 1028-1038
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal vibration control of conical shells with collocated helical sensor/actuator pairs
Optymalne sterowanie drganiami powłok stożkowych za pomocą spiralnego skolokowanego układu czujnika i elementu wykonawczego
Autorzy:
Li, H.
Hu, S. D.
Tzou, H. S.
Chen, Z. B.
Powiązania:
https://bibliotekanauki.pl/articles/280352.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
smart structure
conical shell
diagonal sensor/actuator
optimal vibration control
Opis:
This paper focuses on the optimal vibration control of clamped-free conical shells using distributed helical piezoelectric sensor/actuator (S/A) pairs. Based on the independent modal space control, the response of conical shell to external excitations is represented by the summation of all participating natural modes and their respective modal participation factors, and each mode can be controlled independently. The modal equation is transformed into the linear state space form. The linear quadratic (LQ) controllers are designed for each independent mode. The optimal gain matrix is related to the ratio G∗ between the control voltage and sensing signal by the modal control force per unit voltage B2 and the sensing signal per unit displacement C1. Because B2 and C1 change with locations of the S/A pair, the optimal control effects, modal control forces and corresponding optimal control voltages are evaluated using two S/A pairs at different locations. The results indicate that the optimal control method is effective in vibration control of the shell. The optimal control effect also depends on the location of the S/A pair and modal shapes as well as the modal control force and input voltage.
W pracy skoncentrowano się na problemie optymalnego sterowania drganiami jednostronnie zamocowanych powłok stożkowych za pomocą spiralnie ułożonego układu piezoelektrycznego czujnika skolokowanego z elementem wykonawczym (S/A). W oparciu o wyniki płynące z rozwiązania przestrzennego zagadnienia sterowania modalnego, dynamiczną odpowiedź powłoki na wymuszenie zewnętrzne wyrażono sumą postaci własnych, jednocześnie stwierdzając, że można niezależnie ingerować w poszczególne postaci własne układu. Równanie modalne przetransformowano do liniowej formuły stanu. Zaprojektowano sterowniki liniowo-kwadratowe (LQ) niezależnie dla każdej postaci własnej. Optymalną macierz współczynników wzmocnienia skorelowano z transmitancją G∗ pomiędzy napięciem sterowania i sygnału czujnika poprzez jednostkową siłę sterującą odniesioną do napięcia B2 oraz sygnału czujnika w stosunku do przemieszczenia C1. Ponieważ B2 i C1 zmieniają się wraz ze zmianą położenia skolokowanych par S/A, przeprowadzono ewaluację modalnych sił sterujących i odpowiadających im napięć dla różnych położeń układu sterowania. Wyniki badań potwierdziły efektywność optymalnego sterowania drganiami powłoki stożkowej. Zauważono także wrażliwość uzyskanego stopnia sterowania na położenie pary czujnika i elementu wykonawczego oraz wartości modalnej siły sterującej, jak i napięcia.
Źródło:
Journal of Theoretical and Applied Mechanics; 2012, 50, 3; 769-784
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The CFD method-based research on damaged ship’s flooding process in time-domain
Autorzy:
Hu, Li-Fen
Qi, Huibo
Li, Yuemeng
Li, Wubin
Chen, Shude
Powiązania:
https://bibliotekanauki.pl/articles/259812.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
flooding process
Bernoulli equation
time domain calculation
damaged ship
Opis:
The flooding process is one of the main concerns of damaged ship stability. This paper combines the volume of fluid (VOF) method incorporated in the Navier-Stokes (NS) solver with dynamic mesh techniques to simulate the flooding of a damaged ship. The VOF method is used to capture the fluid interface, while the dynamic mesh techniques are applied to update the mesh as a result of transient ship motions. The time-domain flooding processes of a damaged barge and a rectangular cabin model are carried out based on the abovementioned method, and the computational results appear compatible with the experimental data. During the flooding process, the motion of the flooding flow at different stages is observed and compared with that observed in real conditions. The time-domain research of the flooding process is the starting point for subsequent establishment of damaged ship’s roll movement and capsizing the mechanism of dead ship condition in wave.
Źródło:
Polish Maritime Research; 2019, 1; 72-81
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Morphogenetic Description of Thigmokeronopsis stoecki Shao et al., 2008 (Ciliophora, Hypotricha) and a Comparison with Members of the Family Pseudokeronopsidae
Autorzy:
Chen, Xumiao
Li, Jiqiu
Hu, Xiaozhong
Shao, Chen
Al-Farraj, Saleh A.
Al-Rasheid, Khaled A. S.
Powiązania:
https://bibliotekanauki.pl/articles/763473.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
Tematy:
Hypotrichs, ontogenesis, Pseudokeronopsidae, Thigmokeronopsis
Opis:
The urostylid family Pseudokeronopsidae Borror and Wicklow, 1983 was considered to be a well-outlined taxon. Nevertheless, recent evidence, including morphological, ontogenetic, and molecular information, has consistently revealed the polyphyly of this family. In the present work, a new population of Thigmokeronopsis stoecki Shao et al., 2008 was found and its binary divisional process was described for the first time. In addition, the morphogenetic features of Thigmokeronopsis species and all the other pseudokeronopsids, for which detailed ontogenetic data are available, were rechecked and compared. This reveals that: (1) the ontogenetic process of T. stoecki corresponds well with its congeners T. jahodai and T. rubra except for the macronuclear behavior; (2) Apokeronopsis and Thigmokeronopsis share a similar ontogenetic mode despite of the differences in the number and origin of their buccal cirri; (3) most pseudokeronopsids share the same pattern in the origins of their oral primordia and fronto-ventral-transverse cirral anlagen, except for Pseudokeronopsis similis, which may not be a valid member of the family Pseudokeronopsidae.
Źródło:
Acta Protozoologica; 2013, 52, 2
1689-0027
Pojawia się w:
Acta Protozoologica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Antioxidant activity and mechanism in flower of Hylocereus undatus (Haw.) Britt. et Rose
Autorzy:
Li, X.
Gao, Y.
Han, W.
Lin, J.
Hu, Q.
Chen, D.
Powiązania:
https://bibliotekanauki.pl/articles/19838.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Opis:
Hylocereus undatus flower is commonly used as food or for medicinal purposes in south China. To study its antioxidant activity and mechanism we used antioxidant and chemical assays to compare two commercial samples from different locations (Shenjing, Qixing). The difference in antioxidant levels corresponded with differences in chemical content (including total phenolics, total flavonoids, kaempferol and quercetin) between Shenjing and Qixing. The antioxidant ability of H. undatus flower seems attributable to total phenolics (mainly total flavonoids). Kaempferol is one of the main bioactive components. H. undatus flower exerts its antioxidant effects through metal chelation and radical scavenging via hydrogen atom (H•) and electron (e) donation.
Źródło:
Acta Biologica Cracoviensia. Series Botanica; 2013, 55, 1
0001-5296
Pojawia się w:
Acta Biologica Cracoviensia. Series Botanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of manganese ions addition orders on the flotation behavior of scheelite
Autorzy:
Lu, Kuanwei
Chen, Rong
Zhang, Ying
Luo, Hongying
Yang, Hu
Cai, Jiaozhong
Powiązania:
https://bibliotekanauki.pl/articles/1845215.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
manganese ion
addition order
scheelite
sodium silicate
flotation
Opis:
In this study, the effect of MnCl2 on scheelite flotation with sodium oleate (NaOL) as a collector and sodium silicate as a depressant was assessed by a combination of flotation experiments, Fouriertransform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and solution chemistry. The flotation experiments confirmed that the addition of MnCl2 before sodium silicate showed an adverse effect on flotation and the recovery of scheelite gradually decreased as the amount of MnCl2 was increased. When MnCl2 was added afte r sodium silicate, the recovery of scheelite gradually increased with an increase in the amount of MnCl2. The results of FTIR, XPS, and solution chemistry indicated that MnCl2 acted on the surface of scheelite in the form of manganese ions. When MnCl2 was added before sodium silicate, manganese ions adsorbed on the surface of scheelite reacted with sodium silicate to form a hydrophilic silicate, which covers the surface of scheelite and blocks the adsorption of NaOL. However, when MnCl2 was added after sodium silicate, manganese ions are continued to be adsorbed on the surface of scheelite, which increases the cations on the surface of scheelite, and hence the condition becomes conducive for the interaction between scheelite and NaOL.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 5; 860-873
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New insights into the promotion mechanism of $(NH_4)_2SO_4$ in sulfidization flotation: a combined experimental and computational study
Autorzy:
Chen, Daixiong
Liu, Mengfei
Hu, Bo
Dong, Yanhong
Xue, Wei
He, Peng
Chen, Fang
Zhu, Jianyu
Zhang, Chenyang
Powiązania:
https://bibliotekanauki.pl/articles/1446762.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
malachite
promotion
sulfidization
flotation
mechanism
Opis:
Ammonium sulfate ((NH4)2SO4) exhibits promoting effects in malachite sulfidization flotation. However, the promotion mechanism remains poorly understood. In this study, micro-flotation tests, zeta-potential measurements, scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and materials studio simulation (DFT) were used to investigated the promotion mechanism of $(NH_4)_2SO_4$. Micro-flotation test demonstrates that the recovery of malachite from 73% increased to 83%, when the (NH4)2SO4 was added. Contact angle and zeta potential test results indicate that addition of $Na_2S•9H_2O$ changes the surface properties of malachite and provide the conditions for adsorption of butyl xanthate (BX). After promoting the sulfidization by $(NH_4)_2SO_4$, BX is more effective in improving the hydrophobicity. SEM-EDS and AFM results show that $(NH_4)_2SO_4$ can improve performance and stability of sulfidization. X-ray photoelectron spectroscopy indicates that after sulfidization, polysulfides and cuprous were appeared in malachite surface, infers that a redox reaction occurs between sulfur and copper on the surface of malachite. After addition of $(NH_4)_2SO_4$, the percentage of polysulfides and cuprous were increased, it implies $(NH_4)_2SO_4$ can accelerate the redox reaction. Computational results show that after adding $(NH_4)_2SO_4$, the adsorption energy of HS- on the malachite surface is reduced, implies that $(NH_4)_2SO_4$ can improve the stability of HS-adsorption on the surface of malachite.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 5; 57-70
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
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