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Wyszukujesz frazę "Li, Ping" wg kryterium: Autor


Tytuł:
Research on the linear viscoelastic rheological properties of rejuvenated asphalt mastic based on the discrete element method
Autorzy:
Lin, Mei
Lei, Yu
Li, Ping
Shuai, Jun
Wang, Zhaoli
Powiązania:
https://bibliotekanauki.pl/articles/27312105.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
model konstytutywny
metoda elementów dyskretnych
mastyks asfaltowy odnowiony
właściwości reologiczne
constitutive model
discrete element method
rejuvenated asphalt mastic
rheological characteristics
Opis:
The rheological property of asphalt is an important factor affecting the pavement performance of asphalt binder, and the fundamental reason for the change of asphalt rheological property is the strong evolution of asphalt material meso structure. However, the internal mechanism of rejuvenated asphalt mastic system is complex and its rules are difficult to grasp. Aiming to study the relationship between meso mechanical parameters and rheological parameters of rejuvenated asphalt mastic, the meso structure model of rejuvenated asphalt mastic was established and improved based on the discrete element method. Moreover, the meso parameters of the model were obtained by the objective function method, and then the influences of various factors were studied to construct the mathematical constitutive model of rheological parameter modulus and meso mechanical parameters. Combing with the reliability of the improved Burgers model was verified based on the rheological test results of rejuvenated asphalt mastic. In addition, the virtual test of dynamic shear rheological dynamic frequency scanning was carried out on the asphalt mastic sample by particle flow software. By adjusting the mesomechanical parameters, the simulation results (complex shear modulus and phase angle) were consistent with the test results. This study clarified the relationship between mesomechanics and macro performance, and this model could be used to obtain the complex shear modulus of rejuvenated asphalt mastic under different types, filler-asphalt ratio and external force environments by adjusting particle flow, wall boundary and other conditions, which can greatly save the workload for the later research and provide a theoretical basis for production experiments.
Źródło:
Archives of Civil Engineering; 2023, 69, 2; 399--416
1230-2945
Pojawia się w:
Archives of Civil Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Battery/super-capacitor HESS applied in DC microgrid
Autorzy:
Zhang, Zhen
Baoge Zhang, Baoge
Wang, Donghao
Li, Ping
Rong, Yao
Powiązania:
https://bibliotekanauki.pl/articles/140713.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
battery
bi-directional DC/DC converter
HESS
super-capacitor
voltage closedloop
Opis:
Energy storage technology (EST) is an effective way to improve the power quality of renewable energy generation (such as solar energy and wind energy), but a single energy storage system (ESS) is difficult to meet the demand for the safe operation of the grid. According to the structure and operation characteristics of the existing battery/super-capacitor hybrid energy storage system (HESS), a battery/super-capacitor HESS is proposed. The working principle and three working modes (the super-capacitor pre-charging cold standby mode, the boost mode and buck mode) of the HESS are analyzed in detail. The state equations of the boost mode and buck mode are derived. The state space average method is used to establish the small signal equivalent model under the buck/boost mode. Moreover, the charge and discharge control strategy of the HESS is obtained by combining the voltage closed-loop control. The simulation model is built in Matlab/Simulink to verify the effectiveness of the proposed HESS and its control strategy. The results show that the HESS and its control strategy can ensure the DC bus voltage has good stability and superior anti-interference, and it can simultaneously provide large current, increase the battery life, and improve the technical economy of energy storage.
Źródło:
Archives of Electrical Engineering; 2020, 69, 2; 379-388
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and Curing of Allyl Urethane NIMMO-THF Copolyether with Three Functional Groups as a Potential Energetic Binder
Autorzy:
Wang, Xiaochuan
Li, Ping
Lu, Xianming
Mo, Hongchang
Xu, Minghui
Liu, Ning
Shu, Yuanjie
Powiązania:
https://bibliotekanauki.pl/articles/358158.pdf
Data publikacji:
2020
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
energetic binder
copolyether
nitrile oxide
elastomer
Opis:
A tri-functional NIMMO-THF copolyether (T-NT) was synthesized by polymerization of 3-nitratomethyl-3-methyloxetane (NIMMO) and tetrahydrofuran (THF) in the presence of trimethylolpropane and catalyzed by BF3·OEt2. The allyl urethane NIMMO-THF copolyether with three functional groups (AUT-NT) was synthesized from tri-functional NIMMO-THF copolyether and allyl isocyanate. The polymer was characterized by FT-IR, 1H NMR, and 13C NMR. Furthermore, an elastomer that was prepared from allyl urethane NIMMO-THF copolyether with three functional groups and trimethylisophthalodinitrile oxide (TINO) had satisfactory mechanical properties and good thermal stability. The elastomer is expected to be used in composite solid propellants and polymer-bonded explosives (PBX).
Źródło:
Central European Journal of Energetic Materials; 2020, 17, 1; 141-163
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dexamethasone inhibits U937 cell adhesion via the down-regulation of ROCK1 activity
Autorzy:
Liu, Dong
Chen, Xing
Xiong, Ren
Ning, Ya
Li, Ping
Peng, Yan
Liu, Ping
Zhao, Yan
Yang, Nan
Zhou, Yuan
Powiązania:
https://bibliotekanauki.pl/articles/1039650.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
dexamethasone
ROCK1
fasudil
non-genomic effects
Opis:
Objective. To explore the effect of dexamethasone (DEX) on monocyte adhesion function and its underlying mechanism. Methods. The effects of DEX and fasudil on adhesion of cultured U937 monocytes to human umbilical vein endothelial cells (HUVEC) following stimulation with phorbol myristate acetate (PMA) were studied; Changes in the Rho-associated coiled-coil protein kinase 1 (ROCK1) protein content and activity were evaluated. Results. DEX and fasudil significantly inhibited U937 cell adhesion rates under PMA stimulation and inhibited ROCK1 activity. Mifepristone (RU-486) and cycloheximide (CHX) did not alter these effects of DEX. Conclusions. DEX interferes with the adhesion function of U937 cells through the inhibition of ROCK1 activity.
Źródło:
Acta Biochimica Polonica; 2012, 59, 4; 557-560
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical coherence tomography image for automatic classification of diabetic macular edema
Autorzy:
Wang, Ping
Li, Jia-Li
Ding, Hao
Powiązania:
https://bibliotekanauki.pl/articles/1835815.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
diabetic macular edema
optical coherence tomography
transfer learning
fine-tuning
Opis:
Diabetic macular edema (DME) is the dominant reason of diabetic visual loss, so early detection and treatment of DME is of great significance for the treatment of diabetes. Based on transfer learning, an automatic classification method is proposed to distinguish DME images from normal images in optical coherence tomography (OCT) retinal fundus images. Features of the DME are automatically identified and extracted by the pre-trained convolutional neural network (CNN), which only involves fine-tuning the VGGNet-16 network without any user intervention. An accuracy of 97.9% and a sensitivity of 98.0% are acquired with the OCT images in the Duke data set from experimental results. The proposed method, a core part of an automated diagnosis system of the DME, revealed the ability of fine-tuning models to train non-medical images, allowing them can be classified with limited training data. Moreover, it can be developed to assist early diagnosis of the disease, effectively delaying (or avoiding) the progression of the disease, consequently.
Źródło:
Optica Applicata; 2020, 50, 4; 567-577
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on emergency DC power support coordinated control for hybrid multi-infeed HVDC system
Autorzy:
Li, Congshan
Li, Yikai
Guo, Jian
He, Ping
Powiązania:
https://bibliotekanauki.pl/articles/140422.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
additional controllers
coordinated control
EDCPS
hybrid multi-infeed HVDC system
HVDC
Opis:
Based on the respective characteristics of line-commutated converter highvoltage direct current (LCC-HVDC) and voltage-source converter high voltage direct current (VSC-HVDC), two additional emergency DC power support (EDCPS) controllers are designed, respectively. In addition a coordinated control strategy based on a hybrid multi-infeed HVDC system for EDCPS is proposed. Considering the difference in system recovery between LCC-HVDC and VSC-HVDC in EDCPS, according to the magnitude of the amount of potential power loss, the LCC-HVDC and VSC-HVDC priority issues of boosting power for EDCPS are discussed in detail. Finally, a hybrid three-infeed HVDC that consists of two parallel LCC-HVDCs and one VSC-HVDC that is built in PSCAD/EMTDC are simulated. The effectiveness of the proposed approach is verified based on this hybrid three-infeed HVDC system.
Źródło:
Archives of Electrical Engineering; 2020, 69, 1; 5-21
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Convection rolls and individual particles movements in horizontally vibrated granular particles system
Autorzy:
Rehman, A.
Wu, Ping
Li, Li
Zhang, Shiping
Wang, Li
Powiązania:
https://bibliotekanauki.pl/articles/1058505.pdf
Data publikacji:
2016-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
45.70.-n
47.57.Gc
47.52.+j
47.57.Qk
83.80.Fg
Opis:
Convection in horizontally vibrated granular systems is significant for scientists and engineers for their importance in the field of mining, geo-physics, and pharmaceutical etc. This research work studied three types of convection rolls, "Homogeneous convection roll", "lower-right diagonal convection roll" and "upper-right diagonal convection roll" which occurred in a square container filled with binary granular particles mixture of sized d=(4.0±0.2) mm and d=(8.0±0.2) mm. Container was vibrated horizontally with low frequencies f and low dimensionless acceleration Γ. Helical movement was observed along the walls perpendicular to direction of motion while straight-line movement along the walls horizontal to direction of motion. Helical and straight-line movements of particles along the walls are the part of convection rolls. A heap appeared due to vibration, which has dominant effect on the convection rolls. Heap position is function of frequency f and dimensionless accelerations Γ.
Źródło:
Acta Physica Polonica A; 2016, 130, 6; 1336-1342
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Improvement of damping characteristics and index evaluation of a wind-PV-thermal-bundled power transmission system by combining PSS and SSSC
Autorzy:
He, Ping
Wu, Xinxin
Li, Congshan
Zheng, Mingming
Li, Zhao
Powiązania:
https://bibliotekanauki.pl/articles/140453.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
damping characteristics
eigenvalue analysis
power system stabilizer
wind-PV-thermal-bundled power system
Opis:
The grid integration of large-scale wind and solar energy affects the power flow of wind-PV-thermal-bundled power transmission systems and may introduce an unpredicted threat to the power system’s small signal stability. Meanwhile, a power system stabilizer (PSS) and static synchronous series compensator (SSSC) play an important role in improving the static and dynamic stability of the system. Based on this scenario and in view of the actual engineering requirements, the framework of wind-PV-thermal-bundled power transmitted by an AC/DC system with the PSS and SSSC is established considering the fluctuation of wind and photovoltaic power output and the characteristics of the PSS and SSSC. Afterwards, the situation model is constructed in the IEEE 2-area 4-unit system, and the influence of the PSS and SSSC on the system stability under different operating conditions is analyzed in detail through eigenvalue analysis and time-domain simulation. Finally, an index named the gain rate is defined to describe the improvement of the stability limitations of various wind-PV-thermal operating conditions with the PSS and SSSC. The results indicate (K) that the damping characteristics, dynamic stability and stability limitations for various wind-PV-thermal operating conditions of the wind-PV-thermal-bundled power transmission system can be significantly improved by the interaction of the PSS and SSSC.
Źródło:
Archives of Electrical Engineering; 2020, 69, 3; 705-721
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design and computation of a lightning protection system in an urban 110 kV substation
Autorzy:
Taha, Mohammed Ibrahim
Li, Lin
Wang, Ping
Powiązania:
https://bibliotekanauki.pl/articles/140973.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CDEGS software
fast Fourier transform (FFT)
IEC 62305-3
lightning protection system (LPS)
NFPA 780 level 1
Opis:
A lightning protection system (LPS) of an urban 110 kV substation is designed and analysed according to NFPA 780 and IEC 62305-3 standards. The analysis of the LPS is established on the value of risk assessment. The total area of the plant is described by one soil layer with uniform resistivity. This study aims to improve the understanding of an unexpected manner of the grounding system beneath lightning currents by clarifying the basic concepts of the lightning protection level and the new design procedure in this paper was clarified according to NFPA-780 level 1 for a lightning protection system. The program is integrated with the CDEGS software, which provides effective geometrical modeling with object and result visualization. Furthermore, module and automated fast Fourier transform (FFT) is implemented in this study to simulate electromagnetic fields in the time and frequency domains. These current values are compared to the desired protection levels within the standards. The study results show that for the improved protection of the system against lightning, the total power grid must be considered as a source of improvement for studying shielding influence and the protection levels provided inside this substation.
Źródło:
Archives of Electrical Engineering; 2020, 69, 3; 723-738
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical 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:
An approach to suppress low-frequency oscillation in the hybrid multi-Infeed HVDC of mixed H2/H∞ robust-based control theory
Autorzy:
Li, Congshan
Liu, Yan
Li, Yikai
He, Ping
Fang, Yan
Sheng, Tingyu
Powiązania:
https://bibliotekanauki.pl/articles/2042784.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
additional damping controller
CSP
HMIDC
LFO
mixed 2/∞ control
TLS-ESPRIT
Opis:
A hybrid multi-infeed HVDC (HMIDC) system is composed of line-commutated converter-based high-voltage direct current (LCC-HVDC) and voltage-source converterbased high-voltage direct current (VSC-HVDC), whose receiving ends have electrical coupling. To solve the problem of low-frequency oscillation (LFO) caused by insufficient damping in the HMIDC system, according to the multi-objective mixed 2/∞ output feedback control theory with regional pole assignment, an additional robust damping controller is designed in this paper, which not only has good robustness, but also has strong adaptability to the change of system operation mode. In the paper, the related oscillation modes and transfer function of the controlled plant are obtained, which are identified by the total least squares estimation of signal parameters via rotary invariance technology (TLS-ESPRIT). In addition, the control-sensitive point (CSP) for suppressing LFO based on the small disturbance test method is determined, which is suitable for determining the installation position of the controller. The results show that the control sensitivity factor of VSC-HVDC is greater than that of LCC-HVDC so that adding an additional damping controller to VSC-HVDC is better than LCC-HVDC in suppressing the LFO of HMIDC. Finally, a hybrid double infeed DC transmission system with three receiving terminals is built on PSCAD/EMTDC where the time-domain simulations are performed to verify the correctness of the CSP selection and the effectiveness of the controller.
Źródło:
Archives of Electrical Engineering; 2022, 71, 1; 109-124
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of pH value on effectiveness of biopolymer-based treatment of bauxite mine slurry
Autorzy:
Meng, Jian Ping
Li, Shanmei
Yan, Rongtao
Wei, Changfu
Powiązania:
https://bibliotekanauki.pl/articles/24085778.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pH
biopolymer
xanthan gum
bauxite mine slurry
flocculation
Opis:
Effective dehydration and flocculation of mine slurries or sludge is important for nonferrous metal industries and environmental engineering. However, the mechanisms for the flocculation of slurry remain largely unclear. This paper presents the results of a series of flocculation tests, which was conducted on the slurry suspensions treated by xanthan gum (flocculant) at different pH values. It is shown that the settlement rate of mine slurry particles can be accelerated by adding xanthan gum, and the maximum sedimentation rate was obtained at a pH value of 5.9, and the final volume of flocs is significantly increased due to the addition of the flocculant. In addition, the settlement rates of xanthan gum-treated slurry suspensions at the pH values of 3, 5 and 7 decrease slightly compared with the reference slurry suspensions with pH=5.9, and the slurries remained stable as suspensions at the pH value of 9 and 11. The zeta potential measurement and SEM image analysis show that flocculation occurs primarily due to electrostatic attraction between slurry particles and the flocculants, and the bridging effect between the carboxylic groups in the side chains of xanthan gum molecule and the suspension particles.
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 3; art. no. 167949
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on improving low-frequency oscillation characteristics of wind power grid-connected power system with doubly-fed wind generator based on virtual impedance power system stabilizer
Autorzy:
He, Ping
Zhu, Yongliang
Li, Qiuyan
Fan, Jiale
Tao, Yukun
Powiązania:
https://bibliotekanauki.pl/articles/27309939.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
doubly-fed induction wind turbine
grid-connected wind power
low frequency oscillation
power system stabilizer
virtual impedance
Opis:
The grid integration of large-scale wind power will alter the dynamic characteristics of the original system and the power distribution among synchronous machines. Meanwhile, the interaction between wind turbines and synchronous machines will affect the damping oscillation characteristics of the system. The additional damping control of traditional synchronous generators provides an important means for wind turbines to enhance the damping characteristics of the system. To improve the low frequency oscillation characteristics of wind power grid-connected power systems, this paper adds a parallel virtual impedance link to the traditional damping controller and designs a DFIG-PSS-VI controller. In the designed controller, the turbine active power difference is chosen as the input signal based on residual analysis, and the output signal is fed back to the reactive power control loop to obtain the rotor voltage quadrature component. With DigSILENT/PowerFactory, the influence of the controller parameters is analyzed. In addition, based on different tie-line transmission powers, the impact of the controller on the low-frequency oscillation characteristics of the power system is examined through utilizing the characteristic root and time domain simulation analysis.
Źródło:
Archives of Electrical Engineering; 2023, 72, 3; 811--826
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Frequency control of voltage sourced converter-based multi-terminal direct current interconnected system based on virtual synchronous generator
Autorzy:
Li, Congshan
Zhang, Xiaowei
He, Ping
Zhen, Zikai
Zhao, Kefeng
Powiązania:
https://bibliotekanauki.pl/articles/27309962.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
adaptive droop control
power margin
VSG
virtual synchronous generator
Opis:
In response to the inability of the flexible DC transmission system connected to the AC grid under conventional control strategies to provide inertia to the system as well as to participate in frequency regulation, a virtual synchronous generator (VSG) control strategy is proposed for a voltage source converter (VSC)-based multi-terminal high-voltage direct current (VSC-MTDC) interconnection system. First, the virtual controller module is designed by coupling AC frequency and active power through virtual inertia control, so that the VSC-MTDC system can provide inertia response for AC grid frequency. Second, by introducing the power margin of the converter station into the droop coefficient, the unbalanced power on the DC side is reasonably allocated to reduce the overshoot of the DC voltage in the regulation process. Finally, the power regulation capability of the normal AC system is used to provide power support to the fault end system, reducing frequency deviations and enabling inter-regional resource complementation. The simulation model of the three-terminal flexible DC grid is built in PSCAD/EMTDC, and the effectiveness of the proposed control strategy is verified by comparing the conventional control strategy and the additional frequency control strategy.
Źródło:
Archives of Electrical Engineering; 2023, 72, 4; 971--986
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An effective hybrid method for analysis the large-scale reliability block diagram model
Autorzy:
Ping, Yashi
Ren, Yi
Li, Zhifeng
Yang, Dezhen
Yang, Chao
Powiązania:
https://bibliotekanauki.pl/articles/27312772.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Tematy:
reliability block diagram
structure identification
plus structure
binary decision diagram
Opis:
The reliability block diagram (RBD) is a graphical tool used for reliability modeling and analysis in various industries, including shipbuilding, aviation, and aerospace. Typically, RBDs are transformed into Bayesian networks for quantitative analysis of systems. Bayesian networks are probabilistic graphical models that can capture the uncertainties and causal relationships in complex systems. They can provide various reliability metrics such as failure probability, mean time to failure, availability, etc. However, these techniques have several drawbacks, especially for large-scale models, such as being extremely time and memory-consuming. To address these issues, we propose a hybrid method for quantitative analysis of large-scale RBDs based on the structure identification approach and binary decision diagrams. Theoretical analysis and case verification demonstrate that the proposed method is significantly more efficient than the current one.
Źródło:
Eksploatacja i Niezawodność; 2023, 25, 3; art. no. 169408
1507-2711
Pojawia się w:
Eksploatacja i Niezawodność
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:
The Continuous Growth of Bulk Si by Temperature Gradient Zone Melting Method
Autorzy:
Li, Jiayan
Wang, Liang
Hao, Jianjie
Ni, Ping
Tan, Yi
Powiązania:
https://bibliotekanauki.pl/articles/356541.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
bulk Si
TGZM
Si-Al alloy
growth rate
impurities
Opis:
Temperature gradient zone melting (TGZM) method was used to obtain bulk Si continuously for the efficient separation and purification of primary Si from the Si-Al alloy in this work. The effects of alloy thickness, temperature gradient and holding time in TGZM purification technology were investigated. Finally, the continuous growth of bulk Si without eutectic inclusions was obtained. The results showed that the growth rate of bulk Si was independent of the liquid zone thickness. When the temperature gradient was changed from 2.48 K/mm to 3.97 K/mm, the growth rate of bulk Si was enhanced from 7.9×10-5 mm/s to 2.47×10-4 mm/s, which was increased by about 3 times. The bulk Si could grow continuously and the growth rate was decreased with the increase of holding time from 1 h to 5 h. Meanwhile, low refining temperature was beneficial to the removal of impurities. With a precipitation temperature of 1460 K and a temperature gradient of 2.48 K/mm, the removal rates of Fe, P and B were 99.8%, 94.0% and 63.6%, respectively.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 1; 271-278
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electromechanical transient modeling of energy storage based on virtual synchronous machine technology
Autorzy:
Cui, Juntao
Li, Zhao
He, Ping
Gong, Zhijie
Dong, Jie
Powiązania:
https://bibliotekanauki.pl/articles/2135738.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
battery energy storage system
electromechanical transient model
virtual synchronous machine
Opis:
This paper proposes an electromechanical transient method to build a battery energy storage system-based virtual synchronous generator model, suitable for a large-scale grid. This model consists of virtual synchronous generator control, system limitation and the model interface. The equations of a second-order synchronous machine, the characteristics of charging/discharging power, state of charge, operating efficiency, dead band and inverter limits are also considered. By equipping the energy storage converter into an approximate synchronous voltage source with an excitation system and speed regulation system, the necessary inertia and damping characteristics are provided for the renewable energy power system with low inertia and weak damping. Based on the node current injection method by the power system analysis software package (PSASP), the control model is built to study the influence of different energy storage systems. A study on the impact of renewable energy unit fluctuation on frequency and the active power of the IEEE 4-machine 2-area system is selected for simulation verification. Through reasonable control and flexible allocation of energy storage plants, a stable and friendly frequency environment can be created for power systems with high-penetration renewable energy.
Źródło:
Archives of Electrical Engineering; 2022, 71, 3; 581--599
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on creep-fatigue model of anchored jointed rock mass
Autorzy:
Song, Yang
Fan, Bo
Li, Yong-Qi
Wang, He-Ping
Powiązania:
https://bibliotekanauki.pl/articles/2200878.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
shear creep
anchored jointed rock mass
fractional order
fatigue load
damage
Opis:
To explore the mechanical response of anchored rock mass with an interaction of fatigue and creep, this paper selects the fatigue amplitude and fatigue frequency as influencing factors to carry out a fatigue-creep experiment of the anchored rock mass. Based on fractional order theory and binary perturbation theory, a new fractional order creep model is constructed. The results show that compared with the Burgers model, the newly proposed creep model can better describe the whole process of creep deformation of the anchored jointed rock mass under fatigue loading.
Źródło:
Journal of Theoretical and Applied Mechanics; 2023, 61, 1; 163--173
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Research on Distribution and Morphology of Primary Si Under the Effect of Direct Current
Autorzy:
Li, Jiayan
Njuguna, Benson Kihono
Ni, Ping
Wang, Liang
Tan, Yi
Powiązania:
https://bibliotekanauki.pl/articles/2049663.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
silicon source
direct current
Joule heating
Si morphology
Fe impurity
Opis:
A source of pure silicon was added into an alloy refining system during a refining process with the application of a direct electric current. The effect of the temperature difference between the graphite electrodes and the alloy was decreased. The temperature increase value (ΔT) of the Al-28.51wt.%Si alloy sample caused by Joule heating was calculated by weighing the mass of primary silicon. When the current density was 5.0×105A/m2, the overall temperature increase in the alloy was about 90°C regardless of the alloy composition. Adequate silicon atoms recorded the footprint of the electric current in the alloy melt. The flow convection generated by the electric current in the melt during the solidification process resulted in the refinement of primary silicon. The Fe impurity content in alloy refining without the electric current density was 2.16 ppm. However, it decreased to 1.27 ppmw with the application of an electric current density of 5.0×105A/m2.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 2; 367-372
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-grade mutant OmpF induces decreased bacterial survival rate
Autorzy:
Zhao, Zhi-ping
Liu, Ting-ting
Zhang, Li
Luo, Min
Nie, Xin
Li, Zai-xin
Pan, Yu
Powiązania:
https://bibliotekanauki.pl/articles/1039304.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
antibiotic resistance
mOmpF
OmpF
outer membrane protein
bacterial survival rate
Opis:
OmpF plays very important roles in the influx of antibiotics and bacterial survival in the presence of antibiotics. However, high-grade mutant OmpF and its function in decreasing bacterial survival rate have not been reported to date. In the present study, we cloned a high-grade mutant OmpF (mOmpF) and sequence analysis suggested that over 45 percent of the DNA sequence was significantly mutated, leading to dramatic changes in over 55 percent of the amino acid sequence. mOmpF protein was successfully expressed. When grown in the presence of antibiotic, the bacterial survival rate decreased and the antibiotic inhibition zone became larger with the increase of the mOmpF. It was concluded that concentration of high-grade mutant mOmpF dramatically influenced the bacterial survival rate. The study presented here may provide insights into better understanding of the relationships between structure and function of OmpF.
Źródło:
Acta Biochimica Polonica; 2014, 61, 2; 369-373
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stigmasterol blocks cartilage degradation in rabbit model of osteoarthritis
Autorzy:
Chen, Wei-Ping
Yu, Chong
Hu, Peng-Fei
Bao, Jia-Peng
Tang, Jing-Li
Wu, Li-Dong
Powiązania:
https://bibliotekanauki.pl/articles/1039645.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
matrix metalloproteinases
stigmasterol
osteoarthritis
Opis:
Stigmasterol has been shown exihbit anti-osteoarthritic properties in vitro studies. However, the in vivo effects of stigmasterol on cartilage are still unclear. This study investigated the anti-osteoarthritic properties of stigmasterol on cartilage degradation in a rabbit model of osteoarthritis (OA). Twenty rabbits underwent bilateral anterior cruciate ligament transection (ACLT) to induce OA. Five rabbits were used as normal control. Two weeks after operation, the rabbits were randomly divided into two groups. Each group of 10 rabbits received intra-articular injection with 0.3 ml of stigmasterol in left knees and vehicle in right knees, once weekly. Group 1 was killed 6 weeks after ACLT and 2 were sacrificed 9 weeks after ACLT. The knee joints were assessed by gross morphology, histology and gene expression analysis. We found that expression of genes encoding matrix metalloproteinases (MMPs) was significantly higher while tissue inhibitors of metalloproteinase (TIMP)-1 was significantly lower in the both joints of the two OA groups compared to normal contrals. Stigmasterol reduced the cartilage degradation as assessed by histological analysis and markedly suppressed MMPs expression both in group 1 and group 2. Our results suggest that stigmasterol may be considered as a possible therapeutical agent in the treatment of OA.
Źródło:
Acta Biochimica Polonica; 2012, 59, 4; 537-541
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A stereological ubiquitiformal softening model for concrete
Autorzy:
Ou, Zhuo-Cheng
Li, Guan-Ying
Duan, Zhuo-Ping
Huang, Feng-Lei
Powiązania:
https://bibliotekanauki.pl/articles/281602.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
ubiquitiform
fractal
concrete
softening curve
Opis:
A stereological ubiquitiformal softening model for describing the softening behavior of concrete under quasi-static uniaxial tensile loadings is presented in this paper. In the model, both the damage evaluation process of fracture cross-sections and their distribution along the specimens axis are taken into account. The numerical results of a certain kind of full grade concrete made of crushed coarse aggregate are found to be in good agreement with the experimental data. Moreover, an experiental relation between the lower bound to the scale invariance of concrete and its tensile strength is also obtained by data fitting of the experimental data, which provides an effective approach to determine the lower bound to scale invariance of concrete.
Źródło:
Journal of Theoretical and Applied Mechanics; 2019, 57, 1; 27-35
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On choosability of complete multipartite graphs $K_{4,3*t,2*(k-2t-2),1*(t+1)}$
Autorzy:
Zheng, Guo-Ping
Shen, Yu-Fa
Chen, Zuo-Li
Lv, Jin-Feng
Powiązania:
https://bibliotekanauki.pl/articles/744583.pdf
Data publikacji:
2010
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
list coloring
complete multipartite graphs
chromatic-choosable graphs
Ohba's conjecture
Opis:
A graph G is said to be chromatic-choosable if ch(G) = χ(G). Ohba has conjectured that every graph G with 2χ(G)+1 or fewer vertices is chromatic-choosable. It is clear that Ohba's conjecture is true if and only if it is true for complete multipartite graphs. In this paper we show that Ohba's conjecture is true for complete multipartite graphs $K_{4,3*t,2*(k-2t-2),1*(t+1)}$ for all integers t ≥ 1 and k ≥ 2t+2, that is, $ch(K_{4,3*t,2*(k-2t-2),1*(t+1)}) = k$, which extends the results $ch(K_{4,3,2*(k-4),1*2}) = k$ given by Shen et al. (Discrete Math. 308 (2008) 136-143), and $ch(K_{4,3*2,2*(k-6),1*3}) = k$ given by He et al. (Discrete Math. 308 (2008) 5871-5877).
Źródło:
Discussiones Mathematicae Graph Theory; 2010, 30, 2; 237-244
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of socio-economic spatial structure of urban agglomeration in China based on spatial gradient and clustering
Autorzy:
He, Li
Tao, Jian’ge
Meng, Ping
Chen, Dan
Yan, Meng
Vasa, László
Powiązania:
https://bibliotekanauki.pl/articles/19233717.pdf
Data publikacji:
2021
Wydawca:
Instytut Badań Gospodarczych
Tematy:
economic and social development
urban agglomeration
Central Plains Urban Agglomeration (CPUA)
clustering
spatial gradient
Opis:
Research background: Previous studies on the economic and social development of urban agglomerations mostly focus on a single primacy comparative analysis and efficiency evaluation. Spatial structure differentiation is an important feature of urban agglomeration. The lack of economic and social analysis on the spatial structure makes it impossible to determine the development positioning of each city in the urban agglomeration, which affects the sustainable economic development ability of these areas. Purpose of the article: The objective of the article is to analyze the spatial development law and experience of urban agglomeration, this study explores the practice of economic and population spatial structure of city areas in China. For this purpose, CPUA and its central city Zhengzhou was taken as an example, the spatial gradient structure of example was analyzed. Methods: Using economic and population data of 32 cities in this region, growth pole theory, and pole-axis theory, the economic and population spatial structure of urban agglomeration, the spatial gradient structure of central cities in urban agglomerations were analyzed with the method of cluster about radiation index. Findings & value added: (1) In the process of the formation of CPUA, the geo-graphical spatial pattern plays a decisive role in economic and social development. This is an experience from developing countries. (2) CPUA presents a gradient development pattern with Zhengzhou as the center, and economic and social development gradually radiates to the metropolitan area, the core development area, and the character development demonstration area. (3) The economic and social gradients of Zhengzhou, the central city, present the hierarchy rules and characteristics which are driven by the Beijing-Guangzhou-Railway axis and the Longhai-Railway axis. (4) The central city of Zhengzhou still presents insufficient primacy in regional development, which shows that Zhengzhou accounts for 6% of the population of the Central Plains Economic Zone and 14% of GDP, and insufficient agglomeration. Different countries at different stages of economic development have different urban agglomeration development models. The conclusions from China provide new decision-making ideas and methods for spatial structure research and development strategy analysis of urban agglomerations.
Źródło:
Oeconomia Copernicana; 2021, 12, 3; 789-819
2083-1277
Pojawia się w:
Oeconomia Copernicana
Dostawca treści:
Biblioteka Nauki
Artykuł

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