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Tytuł:
Small-for-gestational age prevalence risk factors in central Appalachian states with mountain-top mining
Autorzy:
Ferdosi, Hamid
Lamm, Steve H.
Afari-Dwamena, Nana A.
Dissen, Elisabeth
Chen, Rusan
Li, Ji
Feinleib, Manning
Powiązania:
https://bibliotekanauki.pl/articles/2161794.pdf
Data publikacji:
2017-10-18
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
tobacco
mining
maternal smoking
small for gestational age
mountain-top mining
SGA prevalence
Opis:
Objectives: To identify risk factors for small-for-gestational age (SGA) for counties in central Appalachian states (Kentucky (KY), Tennessee (TN), Virginia (VA), and West Virginia (WV)) with varied coal mining activities. Material and Methods: Live birth certificate files (1990–2002) were used for obtaining SGA prevalence rates for mothers based on the coal mining activities of their counties of residence, mountain-top mining (MTM) activities, underground mining activities but no mountain-top mining activity (non-MTM), or having no mining activities (non-mining). Co-variable information, including maternal tobacco use, was also obtained from the live birth certificate. Adjusted odds ratios were obtained using multivariable logistic regression comparing SGA prevalence rates for counties with coal mining activities to those without coal mining activities and comparing SGA prevalence rates for counties with coal mining activities for those with and without mountain-top mining activities. Comparisons were also made among those who had reported tobacco use and those who had not. Results: Both tobacco use prevalence and SGA prevalence were significantly greater for mining counties than for non-mining counties and for MTM counties than for non-MTM counties. Adjustment for tobacco use alone explained 50% of the increased SGA risk for mining counties and 75% of the risk for MTM counties, including demographic pre-natal care co-variables that explained 75% of the increased SGA risk for mining counties and 100% of the risk for MTM. The increased risk of SGA was limited to the third trimester births among tobacco users and independent of the mining activities of their counties of residence. Conclusions: This study demonstrates that the increased prevalence of SGA among residents of counties with mining activity was primarily explained by the differences in maternal tobacco use prevalence, an effect that itself was gestational-age dependent. Self-reported tobacco use marked the population at the increased risk for SGA in central Appalachian states. Int J Occup Med Environ Health 2018;31(1):11–23
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2018, 31, 1; 11-23
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Other-projected environmental image: A conceptual framework
Autorzy:
Ji, Li
Powiązania:
https://bibliotekanauki.pl/articles/471181.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Komunikacji Społecznej
Tematy:
conceptual framework
deductive content analysis
environmental image
generic
frames
inductive framing analysis
Opis:
Th is paper aims to develop a conceptual framework for the evaluation of other-projected1 environmental image in an international context. It is based on a case study of an Australian projection of China’s environmental image. By conducting inductive framing analysis and inductive content analysis, the research analyses 315 articles from two of the most important broadsheets in Australia — Th e Australian and Th e Sydney Morning Herald,2 from the year 2000 to 2011, and focuses on three special events. Th e fi ndings reveal four generic frames — environmental problems, environmental governance, global role, and international cooperation and other issue-specifi c frames. Th e research is a fi rst try at conceptualizing a framework for other-projected environmental image.
Źródło:
Central European Journal of Communication; 2014, 7, 1(12); 97-118
1899-5101
Pojawia się w:
Central European Journal of Communication
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-attribute decision-making based on q-rung dual hesitant power dual Maclaurin symmetric mean operator and a new ranking method
Autorzy:
Li, Li
Wang, Jun
Ji, Chunliang
Powiązania:
https://bibliotekanauki.pl/articles/2175106.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
q-rung dual hesitant fuzzy sets
power geometric
dual Maclaurin symmetric mean
power dual Maclaurin symmetric mean
multi-attribute decision-making
Opis:
The ability of q-rung dual hesitant fuzzy sets (q-RDHFSs) in dealing with decision makers’ fuzzy evaluation information has received much attention. This main aim of this paper is to propose new aggregation operators of q-rung dual hesitant fuzzy elements and employ them in multi-attribute decision making (MADM). In order to do this, we first propose the power dual Maclaurin symmetric mean (PDMSM) operator by integrating the power geometric (PG) operator and the dual Maclaurin symmetric mean (DMSM). The PG operator can reduce or eliminate the negative influence of decision makers’ extreme evaluation values, making the final decision results more reasonable. The DMSM captures the interrelationship among multiple attributes. The PDMSM takes the advantages of both PG and DMSM and hence it is suitable and powerful to fuse decision information. Further, we extend the PDMSM operator to q-RDHFSs and propose q-rung dual hesitant fuzzy PDMSM operator and its weighted form. Properties of these operators are investigated. Afterwards, a new MADM method under q-RDHFSs is proposed on the basis on the new operators. Finally, the effectiveness of the new method is testified through numerical examples.
Źródło:
Archives of Control Sciences; 2022, 32, 3; 627--658
1230-2384
Pojawia się w:
Archives of Control Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Pressure Phase Transitions and Thermodynamic Behaviors of Cadmium Sulfide
Autorzy:
Tan, J.
Li, Y.
Ji, G.
Powiązania:
https://bibliotekanauki.pl/articles/1493632.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.15.Mb
65.40.-b
Opis:
The pressure-induced phase transitions of cadmium sulfide semiconductor in both zinc-blende and wurtzite structures are investigated by ab initio plane-wave pseudopotential density functional theory with the local density approximation. On the basis of the fourth-order Birch-Murnaghan equation of state, the phase transition pressures $P_{t}$ are determined by the enthalpy criterion. It is found that the phase transitions occur at pressure of 2.57 GPa (zinc blende-rocksalt structure) and 2.60 GPa (wurtzite-rocksalt structure), respectively. The equilibrium structural parameters, elastic constants, and phase transition pressures are calculated and compared with the experimental data available and other theoretical results. According to linear-response approach, the thermodynamic properties such as the free energy, enthalpy, entropy, and heat capacity are also obtained successfully from the phonon density of state.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 501-506
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and Characterization of CL-20/EPDM by a Crystal Refinement and Spray Drying Method
Autorzy:
Ji, W.
Li, X.
Wang, J.
Powiązania:
https://bibliotekanauki.pl/articles/358349.pdf
Data publikacji:
2015
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
CL-20/EPDM
spray drying
impact sensitivity
thermal stability
Opis:
A 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) based mixed explosive was prepared by a spray drying method using CL-20 suspended in hexane containing EPDM rubber (ethylene-propylene-diene monomer), and made into a stable suspension. The samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), and their thermal stability and impact sensitivity were also measured. The results showed that the ethylene-propylene-diene-monomer rubber (EPDM) can be successfully coated on to the CL-20 crystal surface. Compared to refinement-spray CL-20, the impact sensitivity of CL-20/EPDM was significantly reduced. The characteristic drop height was increased from 28.12 to 39.78 cm. The thermal stability was better than refinement-spray CL-20.
Źródło:
Central European Journal of Energetic Materials; 2015, 12, 4; 831-840
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Response of methane emissions to water levels in simulated constructed wetlands
Autorzy:
Li, Yanran
Xu, Qin
Ji, Shuping
Liu, Jian
Powiązania:
https://bibliotekanauki.pl/articles/2171840.pdf
Data publikacji:
2022
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
methane
Pearson correlation
wetland
temperature water
air temperature
metan
korelacja Pearsona
teren podmokły
temperatura wody
temperatura powietrza
Opis:
Wetland is an important natural source of methane (CH4) generated under the actions of methanogens in the anaerobic environment. A greenhouse experiment was conducted to quantify the response of methane emissions to water levels by simulating three water levels (10, 20, and 40 cm) in constructed wetlands and the methane was determined by the static chamber-gas chromatograph technique. Pearson correlation analysis showed that the emissions of CH4 were positively correlated with water temperature and air temperature while they were negatively correlated with air humidity. The water levels simulation experiment showed that the emission of CH4 was the highest when the water level was 20 cm and the CH4 concentrations of the water-air interface had different patterns at various water levels in the daytime. In conclusion, water level and temperature should be considered when accounting for greenhouse gas emissions in constructed wetlands as they both have important influences on CH4 emission.
Źródło:
Environment Protection Engineering; 2022, 48, 3; 5--12
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ozone detection based on an nitrogen oxide photoacoustic spectroscopy system and chemical reaction
Autorzy:
Jin, Huawei
Ji, Haitao
Wang, Haowei
Li, Shuo
Powiązania:
https://bibliotekanauki.pl/articles/28407430.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
photoacoustic spectroscopy
nitric oxide
ozone
differential detection
spektroskopia fotoakustyczna
tlenek azotu
ozon
dedekcja różnicowa
Opis:
Ozone is known as a “god-given purifying agent”, and its quantitative detection is of great significance. A low-cost photoacoustic spectroscopy (PAS) which is based on absorption at the low-power blue diode emitting at 403.65 nm has been used for nitrogen oxide (NO2) concentration measurements. According to the formula of nitric oxide (NO) reaction and ozone (O3) production of NO2and the differential detection method, a dual-channel PAS system for O3 detection is reported. The consistency of NO2detection with the dual-channel photoacoustic spectroscopy system is good by contrast. The coefficient of determination R2 can still reach 0.846. An intercomparison between the system and a cavity ring-down system (CRDS) was shown to verify the accuracy. The results showed a linear correction factor (R2) of 0.943 in a slope of 0.862±0.002, with an offset of (0.773±0.128) ppb. In addition, the measurement of 3using the dual-channel cavity photoacoustic spectroscopy technique was deployed. These observations indicate that 3concentrations can be effectively observed with the dual-channel PAS instrument.
Źródło:
Environment Protection Engineering; 2023, 49, 4; 73--87
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamic interactions stability analysis of hybrid renewable energy system with SSSC
Autorzy:
He, Ping
Qi, Pan
Ji, Yuqi
Li, Zhao
Powiązania:
https://bibliotekanauki.pl/articles/1841302.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
damping characteristics
dynamic interaction analysis
eigenvalue analysis
hybrid renewable energy system
SSSC
charakterystyka tłumienia
dynamiczna analiza interakcji
analiza wartości własnej
hybrydowy system energii odnawialnej
Opis:
The static series synchronous compensator (SSSC) has demonstrated its capability in providing voltage support and improving power system stability. The objective of this paper is to analyze the dynamic interaction stability mechanism of a hybrid renewable energy system connected with doubly-fed induction generators (DFIGs) and solid oxide fuel cell (SOFC) energy with the SSSC. For this purpose, a linearized mathematical model of this modified hybrid single-machine infinite-bus (SMIB) power system is developed to analyze the physical mechanism of the SSSC in suppressing oscillations and the influence on the dynamic stability characteristics of synchronization. Typical impacting factors such as the series compensation level, the SOFC penetration and tie-line power are considered in the SMIB and two-area systems. The impact of dynamic interactions on enhancing damping characteristics and improving transient performance of the studied systems is demonstrated using eigenvalue analysis and dynamic time-domain simulations, which validates the validity of the proposed physical mechanism simultaneously.
Źródło:
Archives of Electrical Engineering; 2021, 70, 2; 445-462
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on distribution of CO and concentration prediction in blind gallery after blasting operation
Badanie i prognozowanie rozkładu stężenia CO w ślepym wyrobisku po zakończeniu prac strzałowych
Autorzy:
Cao, Y.
Ji, H.
Zhang, Y.
Li, S.
Powiązania:
https://bibliotekanauki.pl/articles/219231.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
rozkład stężenia CO
zależność stężenia od czasu
współczynnik określający równomierność stężenia
współczynnik dyspersji
współczynnik wyrażający spadek stężenia
czas usuwania szkodliwych gazów po zakończeniu prac strzałowych
time-concentration curve
CO concentration distribution
uniformity coefficient
dispersion coefficient
attenuation index
fume-drainage time
Opis:
It is meaningful to study the issues of CO migration and its concentration distribution in a blind gallery to provide a basis for CO monitoring and calculation of fume-drainage time, which is of a great significance to prevent fume-poisoning accidents and improve efficiency of an excavation cycle. Based on a theoretical analysis of a differential change of CO mass concentration and the CO dispersion model in a fixed site, this paper presents several blasting fume monitoring test experiments, carried out with the test location to the head LP in arrange of 40-140 m. Studies have been done by arranging multiple sensors in the arch cross-section of the blind gallery, located at the Guilaizhuang Gold Mine, Shandong Province, China. The findings indicate that CO concentrations in the axial directions are quadratic functions with the Y and Z coordinate values of the cross-section of the blind gallery in an ascending stage of CO time-concentration curve, with the maximum CO concentrations in Y = 150 cm and Z = 150 cm. Also, the gradients of CO concentration in the gallery are symmetrical with the Y = 150 cm and Z = 150 cm. In the descending stage of CO time-concentration curve, gradients of CO concentration decrease in lateral sides and increase in the middle, then gradually decrease at last. The rules of CO concentration distribution in the cross-section are that airflow triggers the turbulent change of the CO distribution volume concentration and make the CO volume concentration even gradually in the fixed position of the gallery. Moreover, the CO volume concentrations decrease gradually, as well as volume concentration gradients in the cross-section. The uniformity coefficients of CO concentration with duct airflow velocities of 12.5 m/s, 17.7 m/s and 23.2 m/s reach near 0.9 at 100-140 m from the heading to the monitoring spot. The theoretical model of a one-dimensional migration law of CO basically coincides with the negative exponential decay, which is verified via fitting. The average effective turbulent diffusion coefficient of CO in the blind gallery is approximate to 0.108 m2/s. There are strong linear relationships between CO initial concentration, CO peak concentrations and mass of explosive agent, which indicates that the CO initial concentration and the CO peak concentration can be predicted, based on the given range of the charging mass. The above findings can provide reliable references to the selection, installation of CO sensors and prediction of the fume-drainage time after blasting.
Badania migracji, rozpływu i rozkładu stężenia CO w ślepym wyrobisku są niezbędne, stanowią one bowiem podstawę do skutecznego monitorowania poziomu CO i obliczania czasu niezbędnego na usunięcie z wyrobiska szkodliwych gazów – jest to kwestia kluczowa dla zapobiegania wypadkom związanych z zatruciem spalinami oraz dla planowania przebiegu prac wydobywczych. W oparciu o teoretyczną analizę zmian stężenia masowego CO i wykorzystując model dyspersji gazu w stałym punkcie, w pracy przedstawiono wyniki eksperymentów przeprowadzonych w ramach monitorowania stężeń gazów powybuchowych w wyrobisku LP na odległości 40-140 m od czoła wyrobiska. Badania prowadzono przy wykorzystaniu zestawu czujników rozmieszczonych w wybranych punktach ślepego wyrobiska w kopalni złota Guilaizhuang, w prowincji Shandong, Chiny. Wyniki badań wskazują, że stężenia CO w kierunkach poosiowych są funkcjami kwadratowymi wartości współrzędnych Y i Z przekroju przekroju ślepego wyrobiska w zakresie krzywej opadającej na wykresie opisującym zależność stężenia CO od czasu, przy czym maksymalne stężenia CO stwierdzono dla Y =150 cm i Z = 150 cm. Ponadto, wykazano że gradienty stężenia CO w wyrobisku są symetryczne dla Y =150 cm i Z =150 cm. W zakresie krzywej rosnącej na wykresie zależności stężenia CO od czasu gradienty stężenia CO wykazują spadek w końcowych regionach wykresu, w środkowej części wykresu notuje się jego wzrost, po czym znów następuje spadek. Na rozkład stężenia CO w tym przekroju wpływ ma fakt że przepływ powietrza wywołuje turbulentne zmiany stężenia objętościowego CO, następnie stężenie objętościowe maleje systematycznie w dalszych częściach wyrobiska. Ponadto, stwierdzono że stężenie CO a także gradienty stężenia objętościowego w przekroju maleją stopniowo. Współczynniki wyrażające równomierność stężenia CO przy przepływach powietrza z prędkością 12.5 m/s 17.7 m/s i 23.2 m/s osiągają wartość 0.9 w punkcie kontrolnym odległym od wyrobiska o 100-140 m. Teoretyczny model jednowymiarowego rozpływu CO zasadniczo pokrywa się z wzorem zależności wykładniczej z wykładnikiem ujemnym, co zostało potwierdzone w procedurze pasowania. Średnia wartość współczynnika dyfuzji CO dla przepływu turbulentnego w ślepym wyrobisku wyniosła 0.108 m2/s. Stwierdzono istnienie silnej zależności liniowej pomiędzy początkowym stężeniem CO, szczytową wielkością stężenia oraz masą użytego materiału wybuchowego, która wskazuje na możliwość prognozowania początkowego i szczytowego stężenia CO w oparciu o zakres wielkości użytego ładunku wybuchowego. Przedstawione wyniki badań stanowić mogą wiarygodną podstawę dla wyboru rodzaju i miejsca zainstalowania czujników CO oraz do prognozowania czasu wymaganego na usuniecie szkodliwych gazów po zakończeniu prac strzałowych.
Źródło:
Archives of Mining Sciences; 2018, 63, 2; 283-300
0860-7001
Pojawia się w:
Archives of Mining Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Yellowfin tuna (Thunnusalbacares) fishing ground forecasting model based on bayes classifier in the South China Sea
Autorzy:
Zhou, W.
Li, A.
Ji, S.
Qiu, Y.
Powiązania:
https://bibliotekanauki.pl/articles/258994.pdf
Data publikacji:
2017
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
Bayes classifier
South China Sea
yellowfin tuna
fishing ground forecasting
Opis:
Using the yellowfin tuna (Thunnusalbacares,YFT)longline fishing catch data in the open South China Sea (SCS) provided by WCPFC, the optimum interpolation sea surface temperature (OISST) from CPC/NOAA and multi-satellites altimetric monthly averaged product sea surface height (SSH) released by CNES, eight alternative options based on Bayes classifier were made in this paper according to different strategies on the choice of environment factors and the levels of fishing zones to classify the YFT fishing ground in the open SCS. The classification results were compared with the actual ones for validation and analyzed to know how different plans impact on classification results and precision. The results of validation showed that the precision of the eight options were 71.4%, 75%, 70.8%, 74.4%, 66.7%, 68.5%, 57.7% and 63.7% in sequence, the first to sixth among them above 65% would meet the practical application needs basically. The alternatives which use SST and SSH simultaneously as the environmental factors have higher precision than which only use single SST environmental factor, and the consideration of adding SSH can improve the model precision to a certain extent. The options which use CPUE’s mean ± standard deviation as threshold have higher precision than which use CPUE’s 33.3%-quantile and 66.7%-quantile as the threshold
Źródło:
Polish Maritime Research; 2017, S 2; 140-146
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anti-overturning safety performance investigation for single column pier bridge
Autorzy:
Ji, Yongcheng
Liu, Wenchao
Li, Wei
Wang, Pixiang
Powiązania:
https://bibliotekanauki.pl/articles/2174020.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
podpora jednokolumnowa
most dźwigarowy
stateczność przeciwwywrotna
modelowanie metodą elementów skończonych
przewrócenie
obciążenie krytyczne
obrót
single column pier
girder bridge
anti overturning stability
finite element modelling
overturn
ultimate load
rotation
Opis:
Under eccentric load, a single column pier bridge often overturns. In order to study the anti overturning performance of a single column pier bridge, taking the accident bridge in Wuxi as an example, a finite element model is established based on ABAQUS. According to the model simulation results, the relationship between the ultimate rotational load and overturning load of the accident bridge is obtained, and the ratio of the latter to the former is 1.75. Based on the model, the stress state, displacement state, and support state of the accident bridge under dead load, highway class I vehicle load, and accident vehicle load are obtained. Whether the strength and stability of the accident bridge under each load meet the service requirements is analyzed. In order to explore the differences among China, United States, and Japan specifications, the lateral stability of accident bridges is checked. It is found that the safety of the United States and Japan specifications is conservative, but the utilization rate of bridge traffic capacity is low. The safety of China specifications is slightly lower, but it can maximize the bridge’s traffic capacity and judge the ultimate overturning state of the bridge more accurately. The research results can provide technical references for the design and application of a single-column pier bridge.
Źródło:
Archives of Civil Engineering; 2022, 68, 3; 221--240
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study on Dynamic Recrystallization Models of 21-4N Heat Resistant Steel
Autorzy:
Li, Yiming
Huang, Xiaomin
Ji, Hongchao
Li, Yaogang
Wang, Baoyu
Tang, Xuefeng
Powiązania:
https://bibliotekanauki.pl/articles/2049422.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
21-4N
hot deformation
dynamic recrystallization
critical strain
volume fraction
Opis:
The high-temperature deformation process and dynamic recrystallization (DRX) process of 21-4N were investigated under the conditions of the deformation temperature range of 1273~1453K, the strain rate range of 0.01~10s-1 and the deformation degree of 60% (the total deformation is 0.916) by using Gleeble-1500D thermal simulated test machine. The curves of stress-strain (σ – ε) were obtained, and the curves of work hardening rate (θ) and strain (ε) were obtained by taking derivative of σ – ε. The DRX critical strains under different conditions were determined by the curves of work hardening rate (θ – ε), and the DRX critical strain model was established. The peak strains of 21-4N were obtained by the curves of σ – ε, the relationship between peak stress (σp) and critical strain (εc) was determined, and the peak strain model was established. The DRX volume fraction models of 21-4N were established by using Avrami equation. The DRX grain size of 21-4N was calculated by Image Pro Plus 6.0, and its DRX grain size models were established.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 1; 145-152
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
HVDC auxiliary emergency power control strategy for power disturbance in two different positions of AC/DC interconnection system
Autorzy:
Li, Congshan
He, Ping
Wang, Youyi
Ji, Yuyi
Yang, Cunxiang
Powiązania:
https://bibliotekanauki.pl/articles/141502.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
unbalanced power
emergency control
power angle stability
frequency stability
control logic
Opis:
High voltage direct current (HVDC) emergency control can significantly improve the transient stability of an AC/DC interconnected power grid, and is an important measure to reduce the amount of generator and load shedding when the system fails. For the AC/DC interconnected power grid, according to the location of failure, disturbances can be classified into two categories: 1) interconnected system tie-line faults, which will cause the power unbalance at both ends of the AC system, as a result of the generator rotor acceleration at the sending-end grid and the generator rotor deceleration at the receiving-end grid; 2) AC system internal faults, due to the isolation effect of the DC system, only the rotor of the generator in the disturbed area changes, which has little impact on the other end of the grid. In view of the above two different locations of disturbance, auxiliary power and frequency combination control as well as a switch strategy, are proposed in this paper. A four-machine two-area transmission system and a multi-machine AC/DC parallel transmission system were built on the PSCAD platform. The simulation results verify the effectiveness of the proposed control strategy.
Źródło:
Archives of Electrical Engineering; 2019, 68, 2; 245-263
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
3D morphological reconstruction of the red blood cell based on two phase images
Autorzy:
Wang, Y
Li, Z
Ji, Y
Xu, Y
Bu, M
Powiązania:
https://bibliotekanauki.pl/articles/174332.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
phase imaging
red blood cell
3D morphological reconstruction
maximum entropy
Opis:
As an important component of blood cells, the red blood cell plays a vital role in many diseases such as malaria and so on. Although quantitative phase imaging techniques can be used for homogeneous cellular thickness distribution to obtain ideal results, they cannot achieve 3D morphological distribution. In this paper, a new method is presented to get a 3D morphology image of red blood cell. With this method, only two cellular quantitative phase images obtained from two orthogonal directions are needed as original information. By using the grid method, the sample is divided into many small phase cubes, and then we take a layer’s cubes into calculation so that the 3D problem could be transformed into a 2D problem to elaborate. Then it can be applied to the tomographic imaging combined with the maximum entropy method according to the two orthogonal phase images. This method has been proved by a simulation of red blood cell. The results show that cellular morphological distribution can be achieved in detail very well just based on only two orthogonal phase images.
Źródło:
Optica Applicata; 2015, 45, 2; 173-182
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of a nonlinear tuned mass damper by using the multi-scale method
Autorzy:
Liu, Junfeng
Yao, Ji
Huang, Kun
Zhang, Qing
Ze, Li
Powiązania:
https://bibliotekanauki.pl/articles/2104766.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
nonlinear characteristics
complex average method
multi-scale method
nonlinear design
control performance
Opis:
A tuned mass damper is a kind of vibration damping device which has been widely used in tall buildings, machinery, bridges, aerospace engineering and other fields. In practical engineering applications, due to large deformation caused by large displacement, errors in engineering constructions and the existence of limit devices, the structure and tuned mass dampers inevitably produce some nonlinear characteristics, but these nonlinearities are often ignored. The results of this study confirm that the nonlinearity of the structure and the mass damper should be considered in the process of optimal frequency design, otherwise there will be a large deviation between the design optimal frequency of the mass damper and the actual optimal frequency. In this paper, nonlinear characteristics of the tuned mass damper and the main structure are considered. The first-order differential equations are obtained by using the complex average method, and the nonlinear equations of the tuned mass damper system are derived by using the multi-scale method. On this basis, the parameters are determined. The numerical results show that the error of the approximate solution method is small in the given example. The nonlinear tuned mass damper with nonlinear design exhibits a better control performance.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 3; 463--477
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł

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