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Wyszukujesz frazę "Chen, Zhang" wg kryterium: Autor


Tytuł:
Real-time equipment condition assessment for a class-imbalanced dataset based on heterogeneous ensemble learning
Ocena stanu sprzętu w czasie rzeczywistym dla zbiorów danych o niezrównoważonym rozkładzie w klasach. Metoda oparta na uczeniu zespołowym
Autorzy:
Chen, Xiaohui
Zhang, Zhiyao
Zhang, Ze
Tematy:
condition assessment
heterogeneous ensemble learning
genetic algorithm
class-imbalanced
ocena stanu
uczenie zespołowe
algorytm genetyczny
niezrównoważony rozkład w klasach
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Wydawca:
Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
Powiązania:
https://bibliotekanauki.pl/articles/300613.pdf  Link otwiera się w nowym oknie
Opis:
This study proposes an ensemble learning model for the purpose of performing a real-time equipment condition assessment. This model makes it possible to plan desired preventive maintenance activities before an unexpected failure takes place. This study focuses on the class-imbalanced problem in equipment condition assessment research. In reality, equipment will experience multiple conditions(states), most of the time remaining in the normal condition and relatively rarely being in the critical condition, which means that, from the perspective of data modelling, the distribution of samples is highly imbalanced among different classes(conditions). The majority of samples belong to the normal condition, while the minority belong to the critical condition, which poses a great challenge to the classification performance. To address this problem, a genetic algorithm-based ensemble learning model is presented. Furthermore, a self-updating learning strategy is presented for online monitoring, contributing to adaptability and reliability enhancement along with time. Many previous studies have attempted feature extraction and to set thresholds for equipment health indicators. This study has an advantage of omitting these steps, as it can directly assess the equipment condition through the proposed ensemble learning model. Numerical experiments, including two types of comparison studies, have been conducted. The results show the greater effectiveness of our proposed model over that of previous research in terms of the stability and accuracy of its classification performance.
W pracy przedstawiono model uczenia maszynowego opartego na zespołach niejednorodnych klasyfikatorów (ensemble learning), który pozwala przeprowadzać ocenę stanu sprzętu w czasie rzeczywistym. Model ten umożliwia zaplanowanie niezbędnych czynności konserwacji profilaktycznej przed wystąpieniem niespodziewanego uszkodzenia. Tematem pracy jest zagadnienie niezrównoważonego rozkładu w klasach poruszane w badaniach dotyczących oceny stanu sprzętu. W warunkach rzeczywistych, sprzęt chrakteryzuje wiele różnych stanów, przy czym przez większość czasu pozostaje on w stanie normalnym, a relatywnie rzadko znajduje się w stanie krytycznym, co oznacza, że z punktu widzenia modelowania danych, rozkład prób w poszczególnych klasach (stanach) jest wysoce niezrównoważony. Większość prób należy do stanu normalnego, a mniejszość do stanu krytycznego, co stanowi duże wyzwanie jeśli chodzi o wydajność klasyfikacji. W celu rozwiązania tego problemu, przedstawiono model uczenia zespołowego oparty na algorytmie genetycznym. Ponadto zaprezentowano samoaktualizującą się strategię uczenia wykorzystywaną do monitorowania online, która wraz z upływem czasu zwiększa adaptacyjność i niezawodność modelu . W wielu poprzednich badaniach podejmowano próby ekstrakcji cech oraz ustalania progów dla wskaźników stanu sprzętu. Zaletą przedstawionej metody jest to, że pozwala ona pominąć te etapy i bezpośrednio oceniać stan sprzętu za pomocą proponowanego modelu uczenia zespołowego. Przeprowadzono eksperymenty numeryczne, w tym dwa rodzaje badań porównawczych. Wyniki pokazują większą skuteczność proponowanego modelu w stosunku do poprzednich badań pod względem stabilności i trafności klasyfikacji.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fractional evolution equation nonlocal problems with noncompact semigroups
Autorzy:
Zhang, X
Chen, P.
Tematy:
fractional evolution equation
mild solution
nonlocal condition
Co-semigroup
condensing maps
measure of noncompactness
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Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Powiązania:
https://bibliotekanauki.pl/articles/254893.pdf  Link otwiera się w nowym oknie
Opis:
This paper is concerned with the existence results of mild solutions to the nonlocal problem of fractional semilinear integro-differential evolution equations. New existence theorems are obtained by means of the fixed point theorem for condensing maps. The results extend and improve some related results in this direction.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of measuring process properties on phosphate rock slurry rheology based on Brookfield method
Autorzy:
Chen, Aoao
Zhang, Qin
Tematy:
phosphate rock
grinding
concentration
rheological properties
apparent viscosity
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/2175436.pdf  Link otwiera się w nowym oknie
Opis:
This research aims to explore how the flotation process conditions influence the rheological properties of phosphate rock slurry. The apparent viscosity of phosphate rock slurry was measured by Brookfield DVNext rheometer. Different mineral types, grinding time, slurry mass concentration and reagent systems were adopted to study the viscosity behavior of phosphate rock slurry. The results showed that under the same conditions, the apparent viscosity of apatite and dolomite slurry was basically the same, and the apparent viscosity of the slurry after mixing the two minerals was basically the same as that of single mineral. For the same slurry concentration, the mineral particle size had a significant effect on the rheological behavior of the slurry, and its apparent viscosity increased exponentially with the decrease of particle size. In addition, phosphate rock slurry showed shear thickening fluids characteristics when the slurry concentration is 20%-40%, but changed to pseudoplastic fluid at high concentration (60%). Sulfuric acid as pH regulator and inhibitor had little effect on the rheology of slurry; when GJBW and NaOL were added as collectors, the rheology of slurry changed, and the effect of GJBW was more obvious.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface modification of fly ash spheroidal particles and their application in the adsorption of phosphorus and chromium(VI) from single and competitive solute systems
Autorzy:
Chen, Chen
Cheng, Ting
Zhang, Xiao
Zhang, Minte
Lv, Ruiyang
Tematy:
fly ash
Langmuir isotherm
adsorption phosphorus
popiół lotny
izoterma Langmuira
adsorpcja fosforu
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Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:
https://bibliotekanauki.pl/articles/2032957.pdf  Link otwiera się w nowym oknie
Opis:
This work focuses on the surface modification of fly ash spheroidal particles and their application in phosphorus and chromium(VI) adsorption. The results show that through surface modification, amorphous silica-alumina gels precipitated on the spheroidal particle surface (by which the microsurface area of the reaction products is effectively enlarged) and the surface zeta potential was changed to fit for adsorbing anions. During the adsorption experiment (single and competitive solute systems), chromium(VI) was easier to adsorb. The surface zeta potential and the existence of competitive ions should be recognized as two important factors affecting adsorption efficiency. A higher temperature could improve the adsorption efficiencies of the two solute systems. The fitting results of the pseudo-second-order model (single and competitive solute systems) show better agreement than those of the pseudo-first-order model at every temperature. The Langmuir adsorption isotherm equation can better simulate the adsorption process in single solute sy039stems, but only the chromium(VI) adsorption process can be fitted by the competitive Langmuir adsorption isotherm in competitive solute systems.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New compensation scheme of magneto-optical current sensor for temperature stability improvement
Autorzy:
Chen, J.
Li, H.
Zhang, M.
Zhang, Y.
Tematy:
magneto-optical current sensor
normalization
Verdet constant
birefringence
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/221874.pdf  Link otwiera się w nowym oknie
Opis:
A novel magneto-optical current sensor (MOCS) with two sensing arms is proposed to improve the temperature stability. One of the arms, with a highly stable permanent magnet attached and orthogonal to the other one, is designed to provide a reference that follows the temperature characteristics of the sensing material. By a normalization operation between two arms, the temperature drift is compensated adaptively and a sensing output proportional to the measured current can be reached. A dual-input and dual-output structure is specially designed for the reference sensing arm to demodulate the DC Faraday rotation angle. This scheme compensates simultaneously two main temperature influence factors, the Verdet constant and linear birefringence. Validation tests were carried out and are discussed.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decay of Electric Charge on Corona Discharge Polyethylene
Autorzy:
Zhang, L.
Xu, Z.
Chen, G.
Tematy:
52.80.-s
81.05.Lg
84.30.Jc
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Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:
https://bibliotekanauki.pl/articles/1807998.pdf  Link otwiera się w nowym oknie
Opis:
In this paper, surface potential decay after corona charge deposition has been investigated for low density polyethylene (LDPE) films. We believe that the three ways of electron charge decay on the surface of insulating polyethylene film is reasonable. The factor of neutralizing with opposite charge in air is negligible, and leakage along insulator surface or through the body is much more important for electron charge decay. Both ways are related with surface voltage of the sample. When the voltage is lower than a critical value, surface leakage contributes most. If the voltage is higher than this value, the electron energy on the surface of the sample exceeds the critical value and it is easy to cross the "deep trap". In this situation, the body leakage is more important, and the decay on the surface of sample speeds. That is why there exists decay curve crossing phenomenon.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of waste heat recovery systems on energy efficiency improvement of a heavy-duty diesel engine
Autorzy:
Ma, Z.
Chen, H.
Zhang, Y.
Tematy:
energy efficiency design index
energy efficiency operational indicator
waste heat recovery system
performance analysis
reduction factor
wskaźnik efektywności energetycznej
wskaźniki eksploatacyjny efektywności energetycznej
system odzysku ciepła odpadowego
analiza wydajności
współczynnik redukcyjny
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/240819.pdf  Link otwiera się w nowym oknie
Opis:
The increase of ship’s energy utilization efficiency and the reduction of greenhouse gas emissions have been high lightened in recent years and have become an increasingly important subject for ship designers and owners. The International Maritime Organization (IMO) is seeking measures to reduce the CO2 emissions from ships, and their proposed energy efficiency design index (EEDI) and energy efficiency operational indicator (EEOI) aim at ensuring that future vessels will be more efficient. Waste heat recovery can be employed not only to improve energy utilization efficiency but also to reduce greenhouse gas emissions. In this paper, a typical conceptual large container ship employing a low speed marine diesel engine as the main propulsion machinery is introduced and three possible types of waste heat recovery systems are designed. To calculate the EEDI and EEOI of the given large container ship, two software packages are developed. From the viewpoint of operation and maintenance, lowering the ship speed and improving container load rate can greatly reduce EEOI and further reduce total fuel consumption. Although the large container ship itself can reach the IMO requirements of EEDI at the first stage with a reduction factor 10% under the reference line value, the proposed waste heat recovery systems can improve the ship EEDI reduction factor to 20% under the reference line value.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimal configuration of energy storage system capacity in traction power supply system considering photovoltaic consumption
Autorzy:
Zhang, Wei
Chen, Xiaoqiang
Wang, Ying
Tematy:
bilevel optimization
capacity optimization configuration
energy storage system
photovoltaic
railway power conditioner
traction power supply system
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Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:
https://bibliotekanauki.pl/articles/59111843.pdf  Link otwiera się w nowym oknie
Opis:
In order to achieve energy savings and promote on-site integration of photovoltaic energy in electrified railways, a topology structure is proposed for the integration of photovoltaic (PV) and the energy storage system (ESS) into the traction power supply system (TPSS) based on a railway power conditioner (RPC). This paper analyzes the composition and operation principles of this structure. To assess the economic benefits brought by the integration of photovoltaic and energy storage systems, a bilevel optimization model is established, with the objectives of optimizing energy storage capacity configuration and photovoltaic energy integration. The KKT (Karush–Kuhn–Tucker) method is employed to transform the model into a single-layer mixed-integer linear programming model, which is then solved using the CPLEX solver in MATLAB. The research findings indicate that, with the configuration of the ESS, the optimal PV consumption rate achieved is 96.8749%. Compared to a 100% PV consumption rate, the ESS capacity configuration is reduced by 13.14%, and the overall operational cost of the TPSS is at its lowest. The study suggests that the proposed bilevel optimization algorithm can more effectively consider PV consumption, leading to enhanced economic performance of the TPSS operation.
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design of Warp-Knitted Single/Double Jacquard Fabric for Shoe Vamp
Autorzy:
Chen, Mengjia
He, Kejie
Zhang, Yan
Wydawca:
Sciendo
Cytata wydawnicza:
He, K., Zhang, Y. & Chen, M. Design of Warp-Knitted Single/Double Jacquard Fabric for Shoe Vamp. Fibres & Textiles in Eastern Europe, 2024, Sciendo, vol. 32 no. 3, pp. 40-49. https://doi.org/10.2478/ftee-2024-0024
Opis:
In order to address the problem of the scarce stitch and color of conventional warp-knitted jacquard fabric, this paper puts forward a method of knitting single/double jacquard shoe vamp fabric with a multiple pattern and color on a high-speed warp knitting jacquard machine. In electronic jacquard systems, lateral movements of jacquard bars, relative to the needle bar, combined with controlled stitch structure and displacement data, facilitate the formation of loop and double loop stitches. And two split jacquard bars in half-gauge in odd and even wales can be threaded in yarns with different colors or varied dyeing performances, then the two-color jacquard effect can be obtained combined with stitch structure design. Taking the specific process as an example, this paper introduces a process design method for single/double jacquard shoe vamp materials, including raw material selection, stitch design, jacquard design, process parameter design, textile finishing design, et al., which can provide a theoretical foundation for the design and development of other warp-knitted jacquard fabrics.
Dostawca treści:
Repozytorium Centrum Otwartej Nauki
Artykuł
Tytuł:
Fault diagnosis of T-type three-level inverter based on bridge voltages
Autorzy:
Chen, Danjiang
Liu, Yutian
Zhang, Shaozhong
Tematy:
bridge voltage
fault diagnosis
fault signal
open-circuit fault
T-type three-level inverter
napięcie mostka
błędna diagnoza
sygnał błędu
błąd obwodu otwartego
falownik trójpoziomowy typu T
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Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:
https://bibliotekanauki.pl/articles/1841372.pdf  Link otwiera się w nowym oknie
Opis:
Multilevel inverters have been widely used in various occasions due to their advantages such as low harmonic content of the output waveform. However, because multilevel inverters use a large number of devices, the possibility of circuit failure is also higher than that of traditional inverters. A T-type three-level inverter is taken as the research object, anda diagnostic study is performed on the open-circuit fault of insulated gate bipolar transistor (IGBT) devices in the inverter. Firstly, the change of the current path in the inverter when anopen-circuit fault of the device occurred, and the effect on the circuit switching states andthe bridge voltages were analyzed. Then comprehensively considered the bridge voltages,and proposed a fault diagnosis method for a T-type three-level inverter based on specificfault diagnosis signals. Finally, the simulation verification was performed. The simulation results prove that the proposed method can accurately locate the open-circuit fault of theinverter device, and has the advantage of being easy to implement.
Dostawca treści:
Biblioteka Nauki
Artykuł

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