Wyniki wyszukiwania - Biblioteka Nauki

1

A multiscale methodology for CFD simulation of catalytic distillation bale packings

100%

Ding H. , Xiang W. , Liu C.

Polish Journal of Chemical Technology

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2016

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tom Vol. 18, nr 1

24--32

EN

A multiscale model for simulating the hydrodynamic behavior of catalytic bale packings has been proposed. This model combines computational fluid dynamics (CFD) and macroscopic calculation. At small scale calculation, the CFD model includes 3-D volume-of-fluid (VOF) simulation within representative elementary unit (REU) under unsteady-state conditions. The REU constitutes gauze and catalyst domain, and porous media model is applied. At large scale calculation, a new mechanistic model deduced from the unit network model is employed. Based on liquid split proportion from small scale calculation, liquid distribution of the entire bale packing can be predicted. To evaluate different packing design, three common bale arrangements, i.e. one-bale, nine-bales and seven-bales, are compared. The area-weighted Christiansen uniformity coefficient is introduced to assess the distribution performance. A comparison between simulation and experimental results is made to validate the multiscale model. The present methodology is proved to be effective to analysis and design of catalytic distillation columns.

2

Graph Based Interference Coordination for Relay Networks

100%

Wang Y. , Li M. , Xiang W.

Przegląd Elektrotechniczny

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2012

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tom R. 88, nr 1b

88-91

EN

Relay networks are subject to two different types of interferences, i.e., inter-cell interference and intra-cell interference. As the inter-cell interference has been well addressed in the literature, this paper is concentrated on intra-cell interference cooperation. An interference graph based interference coordination scheme is proposed to manage the intra-cell co-channel interference. Our extensive simulation results show that the proposed algorithm performs better in both the average throughput and cell edge throughput.

PL

W sieci przekaźnikowej mogą występować dwa rodzaje interferencji – międzykomórkowa i wewnątrzkomórkowa. W artykule skoncentrowano się na tej drugiej interferencji. Schemat bazuje na strukturze grafu interferencji.

3

The application of dynamic bayesian network to reliability assessment of emu traction system

88%

Wang Y. , Bi L. , Wang S. , Lin S. , Xiang W.

Eksploatacja i Niezawodność

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2017

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tom Vol. 19, no. 3

349--357

PL

W artykule omówiono nowatorskie zastosowanie dynamicznej sieci bayesowskiej (DBN) do oceny niezawodności elektrycznego systemu trakcyjnego ze szczególnym uwzględnieniem metod modelowania DBN. W związku z rosnącą złożonością elektrycznych systemów trakcyjnych oraz wynikającą z niej coraz większą ilością współzależności między komponentami, systemy te narażone są coraz częściej na awarie części składowych. Chociaż istnieje wiele badań dotyczących oceny niezawodności systemów trakcyjnych, stosowane obecnie narzędzia nie mają odpowiedniej mocy modelowania koniecznej do opisu zależności funkcjonalnych i czasowych pomiędzy częściami składowymi. W niniejszej pracy zaproponowano nową metodę modelowania generowania DBN, którą można stosować w odniesieniu do systemów składających się z pewnych określonych komponentów oraz różnych typów rozchodzących się przez nie przepływów. Zależności funkcjonalne i czasowe opisano, odpowiednio, za pomocą tablicy komponentowych prawdopodobieństw warunkowych (Component-based Conditional Probability Table, CPT) oraz tablicy czasowo-zależnych prawdopodobieństw warunkowych. Ponieważ złożoność systemu nie pozwala na zamodelowanie go w prosty sposób jako DBN, do automatycznej budowy modelu DBN wykorzystano algorytm przeszukiwania wszerz (Breadth-First-Search). Oceny niezawodności systemu trakcyjnego z wykorzystaniem proponowanej metody opartej na DBN można dokonywać w dowolnym czasie, co ma ogromne znaczenie przy planowaniu konserwacji w celu zapewnienia bezpieczeństwa systemu.

EN

The article introduces a novel application of a Dynamic Bayesian Network (DBN) in the reliability assessment with regard to the traction system of Electric Multiple Units (EMU), which focus on modeling approach to DBN construction. As a result of high complexity and growing interdependencies, it is increasingly vulnerable to the failure of components. Although many studies on the use of BN for estimating the system reliability have been conducted, there is a lack of effective modeling power regarding current tools in depicting both functional and temporal dependencies between components. In this paper, a new modeling approach to DBN generation is submitted, which can be applied to the system made up of certain components and different types of flows propagating through them. The Component-based CPT (Conditional Probability Table) and Time-dependent CPT are used to describe functional dependencies and temporal dependencies respectively. As the complexity of the system cannot be modeled in a tractable way as a DBN, a Breadth-First-Search (BFS) algorithm is introduced for the construction of the DBN model in an automated manner. With the application of the proposed DBN-based approach, the reliability of the traction system can be evaluated at any given time, which is of great significance to determine the plan of maintenance in an effort to ensure the system safety.

4

Quantification of individual tree competition index taking Chinese-fir plantations in subtropical low hilly area as an example

75%

Zhang Y. , Deng X. , Huang Y. , Li Y. , Xiang W. , Yan W.

Polish Journal of Ecology

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2019

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tom 67

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nr 1

EN

Competition among trees is a fundamental interaction process within plant community, which is the theoretical basis of thinning. Plant competitive intensity is generally measured using a competition index (CI) that can be classified into two major categories: distance-independent and distance-dependent. The current study used Cunninghamia lanceolata (Lamb.) Hook as the test subject and used Hegyi's CI (distance-dependent), to quantify individual CI and their relationship with tree diameter at breast height (DBH). Five different criteria were used to select potential competitors for the calculation of CI. Seven basic linear and nonlinear mathematical functions were used to test and quantify the relationships between DBH of the target tree and the individual CI. Results showed that individual CI was negatively correlated with target tree DBH: as DBH increased, competition intensity weakened. The adjusted R² with five different criteria of selection competitors simulated by seven functions ranged from 0.30 to 0.82. Considering the root mean square error (RMSE), P-value, and adjusted-R², our results suggested that the best model to simulate the relationship between individual CI and focal tree DBH was power function (CI = 43.98 × DBH⁻¹‧⁰⁸, adjusted R² = 0.81) and with the Voronoi diagram method as the criteria for selecting competitors. These results can demonstrate a clearer understanding of the spatial structure of forests, and can be used to guide the selection of thinning trees in the process of thinning practice.

5

Improvements in timber production of Chinese fir (Cunninghamia lanceolata) per unit forest area in China via tree breeding: Status and challenges

51%

Zhou B. , Peng D. , Zhao Q. , Yangnan S. , Yang S. , Yang F. , Qu G. , Tang W. , Ou J. , Xiang W. , Xiang J. , Deng X.

Dendrobiology

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2020

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tom 83