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Tytuł:
The development and utilization of bauxite resources in the Guizhou Province and relevant challenges to the ecology and the environment
Rozwój i wykorzystanie zasobów boksytu w prowincji Guizhou oraz istotne wyzwania dla ekologii i środowiska
Autorzy:
Chen, Xiaofu
Li, Xuexian
Wu, Pan
Zha, Xuefang
Liu, Yabin
Wei, Tao
Ran, Wenrui
Powiązania:
https://bibliotekanauki.pl/articles/2173849.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Tematy:
Guizhou Province
bauxite
development of resources
utilization of resources
ecological environment
counter measures
prowincja Guizhou
boksyt
rozwój zasobów
wykorzystanie zasobów
środowisko ekologiczne
środki zaradcze
Opis:
The environmental problems caused by the development and utilization of mineral resources have become important factors affecting ecological security. Guizhou is a Chinese province with relatively developed paleoweathered sedimentary bauxite deposits, abundant resource reserves, and a long history of mining. And, the demand for bauxite in Guizhou is expected to continue to grow. However, long-term or unreasonable resource development has produced a series of prominent environmental problems, such as the occupation and destruction of land resources and heavy metal pollution in soil and water bodies. Based on the existing research results in China and abroad, this paper analyzes the current situation, distribution characteristics, and development and utilization of bauxite resources in Guizhou to explain the corresponding environmental impacts. The results show that because of the many types and high concentrations of associated elements in bauxite and the high alkalinity, heavy metal components, and radioactive elements in red mud, the development and utilization of bauxite resources are associated with higher environmental risk. And more impact of bauxite mining on regional biodiversity, soil, air, surface water, and groundwater need to be evaluated. This paper also proposes coping strategies or countermeasures of environmental governance and control to achieve the green, sustainable and high-quality development of bauxite-related industries for meeting future environmental requirements.
Problemy środowiskowe spowodowane zagospodarowaniem i wykorzystaniem surowców mineralnych stały się ważnymi czynnikami wpływającymi na bezpieczeństwo ekologiczne. Guizhou to chińska prowincja ze względnie rozwiniętymi osadowymi złożami boksytu, bogatymi rezerwami surowców i długą historią wydobycia. Oczekuje się, że popyt na boksyt w Guizhou będzie nadal rósł. Jednak długoterminowy lub nieracjonalny rozwój wykorzystania zasobów spowodował szereg znaczących problemów środowiskowych, takich jak: zajmowanie i niszczenie zasobów ziemi oraz zanieczyszczenie metalami ciężkimi gleby i zbiorników wodnych. W oparciu o istniejące wyniki badań w Chinach i za granicą, w artykule dokonano analizy obecnej sytuacji, charakterystyki dystrybucji oraz rozwoju i wykorzystania zasobów boksytu w Guizhou, w celu wyjaśnienia odpowiedniego wpływu na środowisko. Wyniki pokazują, że ze względu na wiele rodzajów i wysoką koncentrację towarzyszących pierwiastków w boksycie oraz wysoką alkaliczność, składniki metali ciężkich i pierwiastki radioaktywne w czerwonym szlamie, rozwój i wykorzystanie zasobów boksytu wiążą się z wyższym ryzykiem dla środowiska. Ponadto należy ocenić większy wpływ wydobycia boksytu na regionalną bioróżnorodność, glebę, powietrze, wody powierzchniowe i gruntowe. Niniejsza praca proponuje również strategie radzenia sobie lub środki zaradcze zarządzania i kontroli środowiska w celu osiągnięcia ekologicznego, zrównoważonego i wysokiej jakości rozwoju przemysłu związanego z boksytem dla spełnienia przyszłych wymagań środowiskowych.
Źródło:
Gospodarka Surowcami Mineralnymi; 2022, 38, 2; 5--30
0860-0953
Pojawia się w:
Gospodarka Surowcami Mineralnymi
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tensile-tensile Fatigue Behavior of Multi-axial Warp-knitted Reinforced Composite
Ocena właściwości mechanicznych i zmęczeniowych kompozytowych dzianin wieloosiowych
Autorzy:
Gao, X.
Tao, N.
Chen, S.
Wang, L.
Wu, W.
Powiązania:
https://bibliotekanauki.pl/articles/232142.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Biopolimerów i Włókien Chemicznych
Tematy:
multi-axial warp-knitted fabric composite
fatigue behavior
S-N curve
equivalent residual strength
kompozytowe dzianiny wieloosiowe
zmęczenie materiału
krzywa S-N
równoważna wytrzymałość resztkowa
Opis:
An experimental study was carried out on the fatigue behaviour of multi-axial warp-knitted fabric composites. Composite samples reinforced with multi-axial warp-knitted fabric/matrix were manufactured by the vacuum-assisted resin transfer moulding method. Tensile-tensile fatigue cycling was carried out at different load levels, and S-N curves, tensile stress-strain curve and stiffness degradation of the multi-axial composite samples were obtained. Finally post-fatigue tensile tests were done at a stress level of 75%, at the stages of 1/3N and 2/3N, and the equivalent residual strength and stiffness degradation were obtained.
Dokonano oceny właściwości mechanicznych i zmęczeniowych kompozytowych dzianin wieloosiowych. Kompozyty wzmocnione dzianiną wieloosiową wytworzono przy zastosowaniu próżniowej metody formowania. Dokonano oceny zmęczenia materiału i właściwości wytrzymałościowych przy różnych poziomach obciążenia. Przedstawiono krzywe S-N, krzywą naprężenie-odkształcenie i degradację sztywności wieloosiowych próbek kompozytowych. Wykonano również testy zmęczenia materiału przy poziomie naprężenia 75%, w etapach 1/3N i 2/3N. Omówiono równoważną wytrzymałość szczątkową i degradację sztywności kompozytowych dzianin wieloosiowych.
Źródło:
Fibres & Textiles in Eastern Europe; 2018, 1 (127); 73-80
1230-3666
2300-7354
Pojawia się w:
Fibres & Textiles in Eastern Europe
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on Tensile Properties and Microstructures of Different Sites in Al-Si Alloy Casting Component
Autorzy:
Tao, Jianquan
Xiang, Lin
Chen, Xidong
Sun, Jipeng
Wang, Yanbin
Du, Chuanhang
Peng, Feifei
Gao, Shiqing
Chen, Qiang
Powiązania:
https://bibliotekanauki.pl/articles/27765052.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
ZL114A alloy
plaster-mold casting
tensile properties
microstructure
fracture
Opis:
The tensile properties and microstructures of ZL114A alloy component with a complex shape are investigated at room temperature and 200°C, using the tensile tests, scanning electron microscopy and electron backscattering diffraction. Both thin wall and thick structure exhibit excellent properties, of which max ultimate tensile strength and elongation at break reach 314 MPa and 2.5% at room temperature, respectively. The ultimate tensile strengths of thin wall are 40 MPa and 25 MPa greater than those of thick structure at room temperature and 200°C, respectively. Moreover, the eutectic Si phases of thin wall exhibit a predominantly spherical morphology while of the morphology of thick structure are rod-like, resulting in the different mechanical properties between thin wall and thick structure. The fracture morphologies of thin wall and thick structure are studied to explain the difference in performance between thin wall and thick structure.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 2; 585--589
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on separation of fine-particle ilmenite and mechanism using flocculation flotation with sodium oleate and polyacrylamide
Autorzy:
Peng, Yang
Xiao, Junhui
Deng, Bing
Wang, Zhen
Liu, Nengyun
Yang, Daoguang
Ding, Wei
Chen, Tao
Wu, Qiang
Powiązania:
https://bibliotekanauki.pl/articles/1450088.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
sodium oleate
polyacrylamide
synergistic effect
ilmenite
flocculation flotation
Opis:
In this paper, sodium oleate, polyacrylamide, soluble starch and sodium carboxymethyl cellulose were used as flocculants to study the flocculation and sedimentation behavior of microfine ilmenite. Sedimentation test shows that sodium oleate and polyacrylamide have good flocculation effect on ultrafine ilmenite. The flocculation rate of ilmenite can be further improved by the combination of sodium oleate and polyacrylamide. It was found that both flocculants could generate chemical adsorption with ilmenite surface, and they all react with $Fe^{3+}$ on ilmenite surface. However, sodium oleate reacts with $Fe^{3+}$ to form a water-insoluble iron oleate precipitate which coats the surface of the ilmenite and hinders the action of polyacrylamide and the remaining $Fe^{3+}$. This problem can be avoided by adding polyacrylamide followed by sodium oleate, and the flotation recovery can be increased significantly.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 1; 161-172
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatiotemporal analysis of air quality and its relationship with meteorological factors in the Yangtze River Delta
Autorzy:
Li, Y.
Chen, Y.
Karimian, H.
Tao, T.
Powiązania:
https://bibliotekanauki.pl/articles/1192096.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Tematy:
YRD
air quality index
meteorological elements
correlation analysis
air pollution
spatial analysis
Opis:
Air quality is closely related to people’s health and life. In addition to being directly affected by social activities and atmospheric emissions, the impacts of meteorological factors are also significant. Based on daily Air Quality Index (AQI) data and various meteorological parameters in the Yangtze River Delta (YRD), this paper summarized the spatiotemporal evolution characteristics of AQI over YRD, and quantitatively analyzed the contribution of different meteorological elements to air quality. We also evaluated different spatial interpolation methods to produce surface distribution of AQI, and noted that the Ordinary Kriging outperformed other methods. The spatial distribution of AQI in YRD showed seasonal and annual variations. However, the days with AQI over 100 (level ii) were mostly observed in winter. Generally, more severe air pollution was observed in the northern part of YRD than in the southern ones, for example the air quality of the Ningbo metropolitan area was the best, while in Hefei it was the worst. It was found that meteorological parameters have spatially varying effects on AQI. For instance, pressure has a significant positive effect on AQI, and others showed negative correlations. We also predicted AQI by exploiting different machine learning-based models. Through model comparison, it was found that the Autoregressive Integrated Moving Average Model – ARIMA (0,1,2) has higher prediction accuracy for AQI than Multiple Linear Regression (MLR). The findings of this research can be used in future forecasting of air pollution, and also in air pollution controlling programs.
Źródło:
Journal of Elementology; 2020, 25, 3; 1059-1075
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seroepidemiological study of canine Leishmania infantum and Toxoplasma gondii infections in Shanghai, China, and analysis of risk factors
Autorzy:
Jiang, Wei
Wang, Yan
Liu, Yingchun
Li, Tao
Chen, Yongjun
Wang, Shaohui
Han, Xiangan
Wang, Quan
Powiązania:
https://bibliotekanauki.pl/articles/990968.pdf
Data publikacji:
2016
Wydawca:
Instytut Medycyny Wsi
Tematy:
seroprevalence
leishmania infantum
toxoplasma gondii
household dogs
risk factors
Opis:
The aim of this study was to determine the seroprevalence of Leishmania infantum and Toxoplasma gondii among household dogs in Shanghai (the most important industrial and commercial city in China), and to assess the possible risk factors associated with the infection. During 2014–2015, a total of 408 sera were collected from healthy household dogs and tested for L. infantum and T. gondii infection using commercial ELISA kits. The endemic characteristics according to gender, age group and breed were revealed by statistical descriptions and inference. The positive rates of L. infantum infection (24/408, 5.9%) were lower than those of T. gondii infection (37/408, 9.1%), and co-infection with both parasites was detected in seven dogs (7/408, 1.7%). Seropositivity for either parasite was more likely associated with age: the seroprevalence of T. gondii infection ranged from 1.3% (dogs≤1 year) – 18.7% (dogs>6 years), whereas that of L. infantum ranged from 1.3% (dogs≤1 year) – 9.9 % (dogs>6 years). Interestingly, the rates of exposure to both L. infantum and T. gondii were higher in males than in females. Relatively higher exposure rates for L. infantum and T. gondii were also observed in crossbred dogs compared with purebred dogs. However, neither gender nor breed is likely a determining factor for infection with these two parasites (P > 0.05). Identification of the risk factors that underlie these differences may help in the prevention of L. infantum and T. gondii infection in household dogs. To the best of our knowledge, this is the first report of L. infantum and T. gondii infection in household dogs in Shanghai, which shows that these two important parasites are still prevalent in this region. Therefore, it is necessary to take integrated strategies for prevention and control of infection in animals, which could help to reduce human infection in the region.
Źródło:
Annals of Agricultural and Environmental Medicine; 2016, 23, 3
1232-1966
Pojawia się w:
Annals of Agricultural and Environmental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Harmonic mitigation in 18-pulse rectifier based on zigzag autotransformer by DC side auxiliary circuit
Autorzy:
Liu, Jiongde
Chen, Xiaoqiang
Wang, Ying
Chen, Tao
Powiązania:
https://bibliotekanauki.pl/articles/949860.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
18-pulse rectifier
harmonic suppressing
zigzag autotransformer
Opis:
To improve the power quality of a multi-pulse rectifier, a zigzag 18-pulse uncontrolled rectifier with an auxiliary circuit at the DC side is proposed. When the grid-side currents are sinusoidal waves, the required DC side injection currents to be compensated can be obtained by analyzing the AC-DC side relationship of diode bridge rectifiers. Then the 6 compensation currents generated by an active auxiliary circuit are injected into the DC side to eliminate the grid-side harmonics of the rectifier. The simulation results verifying the correctness of the theoretical analysis show that the proposed rectifier can mitigate the harmonic content, as the total harmonic distortion of the grid-side current is about 1.45%. In addition, the single-phase inverter used in the active auxiliary circuit has the characters of simple circuit structure and easy controllability.
Źródło:
Archives of Electrical Engineering; 2020, 69, 4; 891-905
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geomagnetic detection method for pipeline defects based on ceemdan and WEP-TEO
Autorzy:
Zhang, Tao
Wang, Xinhua
Chen, Yingchun
Shuai, Yi
Ullah, Zia
Ju, Haiyang
Zhao, Yizhen
Powiązania:
https://bibliotekanauki.pl/articles/220762.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
geomagnetic detection
pipeline defects
magnetic field
filtering
data processing
Opis:
This paper presents a geomagnetic detection method for pipeline defects using complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and wavelet energy product (WEP) - Teager energy operator (TEO), which improves detection accuracy and defect identification ability as encountering strong inference noise. The measured signal is first subtly decomposed via CEEMDAN into a series of intrinsic mode functions (IMFs), which are then distinguished by the Hurst exponent to reconstruct the filtered signal. Subsequently, the scale signals are obtained by using gradient calculation and discrete wavelet transform and are then fused by using WEP. Finally, TEO is implemented to enhance defect signal amplitude, completing geomagnetic detection of pipeline defects. The simulation results created by magnetic dipole in a noisy environment, indoor experiment results and field testing results certify that the proposed method outperforms ensemble empirical mode decomposition (EEMD)-gradient, EEMD-WEP-TEO, CEEMDAN-gradient in terms of detection deviation, peak side-lobe ratio (PSLR) and integrated side-lobe ratio (ISLR).
Źródło:
Metrology and Measurement Systems; 2019, 26, 2; 345-361
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study on triboelectrostatic beneficiation of wet fly ash using Microwave Heating
Autorzy:
Li, H.
Chen, Y.
Zhang, X.
Zhao, Y.
Tao, Y.
Li, C.
He, X.
Powiązania:
https://bibliotekanauki.pl/articles/110399.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
wet fly ash
triboelectrostatic beneficiation
microwave heating
efficiency
Opis:
Triboelectrostatic beneficiation, as a physical method, of fly ash cannot only meet the technical requirements of fly ash application but also recycle of an unburned carbon as a useful energy source. The aim of this study was to investigate the feasibility of improving efficiency of triboelectrostatic beneficiation of wet fly ash using microwave heating. The wet fly ash with different moisture contents had an average loss-on-ignition of 12.56%. The fly ash samples were heated in a microwave oven before the experiments. The experimental conditions were electric field voltage of 40 kV and air flux ranging from 12 to 30 m3/h. The influence of the microwave heating on the wet fly ash triboelectrostatic beneficiation was discussed under the conditions of different microwave intensity and irradiation time. The results indicated that the removal rate and recycle rate of the unburned carbon showed a significant increase performance as the wet fly ash was processed by the microwave heating which was attributed to changes of moisture contents and dielectric constants caused by the microwave heating. The feasibility had been verified according to the experimental study on fly ash with different moisture contents. It can be concluded that the microwave heating process was efficiently applied for the wet fly ash triboelectrostatic beneficiation.
Źródło:
Physicochemical Problems of Mineral Processing; 2016, 52, 1; 328-341
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Empirical Study of the Evolution of Python Questions on Stack Overflow
Autorzy:
Syam, Gopika
Lal, Sangeeta
Chen, Tao
Powiązania:
https://bibliotekanauki.pl/articles/9783959.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Python programming
Software Development
Stack Overflow
Topic Modelling
Opis:
Background: Python is a popular and easy-to-use programming language. It is constantly expanding, with new features and libraries being introduced daily for a broad range of applications. This dynamic expansion needs a robust support structure for developers to effectively utilise the language. Aim: In this study we conduct an in-depth analysis focusing on several research topics to understand the theme of Python questions and identify the challenges that developers encounter, using the questions posted on Stack Overflow. Method:We perform a quantitative and qualitative analysis of Python questions in Stack Overflow. Topic Modelling is also used to determine the most popular and difficult topics among developers. Results: The findings of this study revealed a recent surge in questions about scientific computing libraries pandas and TensorFlow. Also, we observed that the discussion of Data Structures and Formats is more popular in the Python community, whereas areas such as Installation, Deployment, and IDE are still challenging. Conclusion: This study can direct the research and development community to put more emphasis on tackling the actual issues that Python programmers are facing.
Źródło:
e-Informatica Software Engineering Journal; 2023, 17, 1; 230107
1897-7979
Pojawia się w:
e-Informatica Software Engineering Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective sensor placement based on a VIKOR method considering common cause failure in the presence of epistemic uncertainty
Autorzy:
Duan, Rong-Xing
He, Jie-Jun
Feng, Tao
Huang, Shu-Juan
Chen, Li
Powiązania:
https://bibliotekanauki.pl/articles/1841697.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
dynamic fault tree
epistemic uncertainty
sensor placement
reliability criterion
diagnostic sensor model
Opis:
Owing to expensive cost and restricted structure, limited sensors are allowed to install in modern systems to monitor the working state, which can improve their availability. Therefore, an effective sensor placement method is presented based on a VIKOR algorithm considering common cause failure (CCF) under epistemic uncertainty in this paper. Specifically, a dynamic fault tree (DFT) is developed to build a fault model to simulate dynamic fault behaviors and some reliability indices are calculated using a dynamic evidence network (DEN). Furthermore, a VIKOR method is proposed to choose the possible sensor locations based on these indices. Besides, a sensor model is introduced by using a priority AND gate (PAND) to describe the failure sequence between a sensor and a component. All placement schemes can be enumerated when the number of sensors is given, and the largest system reliability is the best alternative among the placement schemes. Finally, a case study shows that CCF has some influence on sensor placement and cannot be neglected in the reliabilitybased sensor placement.
Źródło:
Eksploatacja i Niezawodność; 2021, 23, 2; 253-262
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of grinding media on the flotation of copper-activated marmatite
Autorzy:
Long, Tao
Chen, Yao
Shi, Juanjuan
Chen, Wei
Zhu, Yangge
Zhang, Chonghui
Bu, Xianzhong
Powiązania:
https://bibliotekanauki.pl/articles/109857.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
grinding media
copper-activated marmatite
flotation separation
surface property
Opis:
How to avoid the shortage of floatability and non-purpose flotation in marmatite flotation is a big problem. This paper innovatively studies how to reduce these two negative phenomena from the perspective of grinding media. The effects of steel and stainless-steel balls on the flotation performance of copper-activated marmatite were investigated mainly through flotation tests, redox potential measurements, ion concentration tests, and XPS and FT-IR spectrum studies. The flotation results showed that the floatability of copper-activated marmatite remarkably decreased by using the steel ball in the grinding process, but it had a mere influence when stainless-steel medium was used. Redox potential measurements showed that the grinding environment of stainless-steel medium could exhibit a higher oxidizing potential than the steel grinding environment. Results from FTIR, XPS, and ion concentration measurements demonstrated that more ferric ions existed on the copper activated marmatite surface in the steel grinding environment than that in the stainless-steel environment. Ferric ions could further hinder the activation effect of copper ions on marmatite and result in decreased marmatite flotation. This research could potentially explain the mechanism of ferric ions in the grinding process, and it can be utilized to improve the flotation performance of marmatite ore through selecting suitable grinding media in ball mill operations.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 2; 229-237
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and Analysis of Ultrasonic Composite Transducer with a Quarter-wave Taper Transition Horn
Autorzy:
Chen, Tao
Li, Hongbo
Wang, Qihan
Ye, Junpeng
Powiązania:
https://bibliotekanauki.pl/articles/1953535.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
equivalent circuit
composite transducer
quarter-wave
prestressed bolt
finite element analysis
Opis:
Based on the electromechanical equivalent circuit theory, equations related to the resonance frequency and the magnifying coefficient of a quarter-wave vibrator and a quarter-wave taper transition horn were deduced, respectively. A series of 3D models of ultrasonic composite transducers with various conical section length was also established. To reveal the influences of the conical section length and the prestressed bolt on the dynamic characteristics (resonance frequency, amplitude, displacement node, and the maximum equivalent stress) of the models and the design accuracy, finite element (FE) analyses were carried out. The results show that the addition of prestressed bolt increases the resonance frequency and causes the displacement node on the center axis to move towards the small cylindrical section. As the conical section length rises, the increment of resonance frequency reduces and tends to a stable value of 360 Hz while the displacement of the node on the center axis becomes lager and gradually approaches 1.5 mm. Furthermore, the amplitude of the output terminal is stable at 16.18 µm under 220 V peak-topeak (77.8 VRMS) sinusoidal potential excitation. After that, a prototype was fabricated and validated experiments were conducted. The experimental results are consistent with that of theory and simulations. It provides theoretical basis for the design and optimization of small-size, large-amplitude, and high-power composite transducers.
Źródło:
Archives of Acoustics; 2020, 45, 4; 687-697
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coelacanths from the Middle Triassic Luoping Biota, Yunnan, South China, with the earliest evidence of ovoviviparity
Autorzy:
Wen, W.
Zhang, Q.-Y.
Hu, S.-X.
Benton, M.J.
Zhou, C.-Y.
Tao, X.
Huang, J.-Y.
Chen, Z.-Q.
Powiązania:
https://bibliotekanauki.pl/articles/23008.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
coelacanth
Middle Triassic
Triassic
Yunnan province
South China
China
evidence
ovoviviparity
Anisian
Actinistia
Coelacanthoidei
Latimerioidei
Opis:
The fossil record of coelacanths is patchy, with very few taxa known from the Triassic of Asia. We report here two new genera and species of coelacanths from the Luoping Biota, a recently found site of exceptional fossil preservation from Yunnan, South China. The first new taxon, Luopingcoelacanthus eurylacrimalis, is based on four specimens, which to− gether show most aspects of the anatomy. One specimen shows two small coelacanths inside the ventral portion of the ab− dominal cavity, and these are interpreted as intrauterine embryos, close to birth size, based on comparisons with previ− ously reported embryos of the fossil coelacanths Rhabdoderma and Undina, and the extant genus Latimeria. Our new find extends the evidence for ovoviviparity in coelacanths back from the Late Jurassic to the Middle Triassic. The second new taxon, Yunnancoelacanthus acrotuberculatus, is based on one specimen, and differs from Luopingcoelacanthus in the dentary, lachrymojugal, number of rays of the first dorsal fin, and especially in the ornament on dermal bones and scales. Acladistic analysis shows that the new taxa are closest relatives to the derived clade Latimerioidei. The relatively high di− versity of coelacanths in the Early Triassic, and adaptations of living Latimeria to low−oxygen conditions, suggests that the group may have included ‘disaster taxa’ that benefited from anoxic and dysoxic ocean conditions in the aftermath of the end−Permian mass extinction.
Źródło:
Acta Palaeontologica Polonica; 2013, 58, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterized Microstructure and Electrical Properties of Hydrogenated Nanocrystalline Silicon Films by Raman and Electrical Conductivity Spectra
Autorzy:
Xiao-Yong, Gao
Jian-Tao, Zhao
Yu-Fen, Liu
Qing-Geng, Lin
Yong-Sheng, Chen
Jin-Hua, Gu
Shi-E, Yang
Jing-Xiao, Lu
Powiązania:
https://bibliotekanauki.pl/articles/1808127.pdf
Data publikacji:
2009-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.23.Cq
73.61.-r
Opis:
Microstructure and electrical properties of hydrogenated nanocrystalline silicon (nc-Si:H) film deposited on glass substrate at low temperature were characterized by average grain size, crystallinity, and dark electrical conductivity data obtained from the Raman and electrical conductivity spectroscopy, respectively. The average grain size, crystallinity and electrical conductivity have a similar change with substrate temperature. A threshold substrate temperature determined by silane concentration appears in their corresponding spectroscopy vs. substrate temperature. The dependence of crystallinity, average grain size and electrical conductivity on substrate temperature were accounted for by surface diffusion model and heterojunction quantum dot model, respectively.
Źródło:
Acta Physica Polonica A; 2009, 115, 3; 738-741
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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