Wyniki wyszukiwania - BazTech

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Modification Mechanism and Growth Process of Al3(Sc, Zr) Particles in As-cast Al-Si-Mg-Cu-Zr-Sc Alloy

Li Y., Du X., Fu J., Zhang Y., Zhang Z., Zhou S., Wu Y.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 2

51--56

EN

In this study, the modification mechanism and growth process of Al3(Sc, Zr) particles in as-cast Al-Si-Mg-Cu based alloy with addition of Sc and Zr were systematically investigated. It was found that 0.57 wt-%Sc addition caused a significant refinement in the average grain size of the investigated alloy, which brought about a remarkable transformation in as-cast microstructure, from thick dendritic shape to fine equiaxed structure. A large amount of primary Al3(Sc, Zr) particles with the dimension of around 5-6 μm were also observed within the equiaxed grain. Due to the identical orientation and similar crystal structure between primary Al3(Sc, Zr) particles and α-Al matrix, the primary particles always served as heterogeneous nucleus for the α-Al matrix. In addition, these cusped cubic primary Al3(Sc, Zr) particles showed triangle, star, rhomboid morphologies are generated from sectioning the particle in (111), (100) and (110) planes, respectively. Particularly, the typical eutectic structure which contained odd number-layer (Al3(Sc, Zr)+α-Al+ ... +Al3(Sc, Zr)) was observed within the investigated particles.

2

Research on marine fhotovoltaic power forecasting based on Wavelet Transform and Echo State Network

Du X., Wang S., Zhang J.

Polish Maritime Research

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2017

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S 2

53--59

EN

With the rapid development of photovoltaic power generation technology, photovoltaic power generation system has gradually become an important component of the integrated energy system of marine. High precision short-term photovoltaic power generation forecasting is becoming one of the key technologies in ship energy saving and ship energy efficiency improving. Aiming at the characteristics of marine photovoltaic power generation system, we designed a highprecision power forecasting model (WT+ESN) for marine photovoltaic power generation system with anti-marine environmental interference. In this model, the information mining of the photovoltaic system in marine environment is carried out based on wavelet theory, then the forecasting model basing on echo state network is construct ed. Lastly, three kinds of error metrics are compared with the three traditional models by Matlab, the result shows that the model has high forecasting accuracy and strong robustness to marine environmental factors, which is of great significance to save fuel for ships, improve the energy utilization rate and assist the power dispatching and fuel dispatching of the marine power generation system.

3

A Deep Q-Learning Network for ship stowage planning problem

Shen Y., Zhao N., Xia M., Du X.

Polish Maritime Research

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2017

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S 3

102--109

EN

Ship stowage plan is the management connection of quae crane scheduling and yard crane scheduling. The quality of ship stowage plan affects the productivity greatly. Previous studies mainly focuses on solving stowage planning problem with online searching algorithm, efficiency of which is significantly affected by case size. In this study, a Deep Q-Learning Network (DQN) is proposed to solve ship stowage planning problem. With DQN, massive calculation and training is done in pre-training stage, while in application stage stowage plan can be made in seconds. To formulate network input, decision factors are analyzed to compose feature vector of stowage plan. States subject to constraints, available action and reward function of Q-value are designed. With these information and design, an 8-layer DQN is formulated with an evaluation function of mean square error is composed to learn stowage planning. At the end of this study, several production cases are solved with proposed DQN to validate the effectiveness and generalization ability. Result shows a good availability of DQN to solve ship stowage planning problem.

4

Bearing capacity of tempered glass panel in point supported glass facades against in-plane load

Wang Z., Wang Y., Liang Y., Du X., Shi Y.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 4

935--948

EN

Tempered glass panels in the point supported glass facade (PSGF) are usually subjected to large in-plane load. In order to investigate the bearing capacity of tempered glass panels against in-plane load, three tests are firstly carried out. Afterwards, finite element method (FEM) is adopted to study stresses around holes under different loading conditions and explore the influence of the in-plane load on the stress distribution of the glass panel. It is concluded that stresses around holes in tempered glass panels are principally affected by the in-plane load, while stresses at centers of the surface and edges are mainly controlled by the out-of-plane load. When the in-plane load is relatively high, the out-of-plane load is probably able to reduce stresses at some points around holes, contributing to the improvement of the load-bearing capacity of tempered glass panels. If the in-plane load is large enough, specimens are bound to experience state transitions which are caused by large plastic deformation of stainless steel bolt fittings and result in the rapid increase of stresses on glass panels. Therefore, by enhancing the shear strength of bolt fittings one can improve the bearing capacity of tempered glass panels in the PSGF against the in-plane load.

5

Fan Y., Du X., An Z., Liu J., Tan D., Chen J.

Acta Geophysica

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2015

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Vol. 63, no. 3

679--697

EN

The changes of the ionospheric electric field before and after four huge earthquakes, which include the Ms 8.7 earthquake of 2004 and the Ms 8.5 earthquake of 2005 in Sumatra of Indonesia, the Ms 8.0 Wenchuan earthquake of 2008 in China, the Ms 8.8 earthquake of 2010 in Chile, and their strong aftershocks are studied in this paper. The significant results revealed that the power spectral density of low-frequency electric field below 20 Hz in the ionosphere, a kind of electromagnetic radiation phenomena, increased abnormally before and after the earthquakes and partially corresponded to the increased power spectral density of the low-frequency geoelectric field in time. This research preliminarily indicates that the low-frequency electromagnetic radiation during the imminent stages before such earthquakes could be detected by the observation of the ionospheric electric field. However, the spatial, temporal, and intensive complexities of the electric field anomalies in the ionosphere before earthquakes have come in sight also.

6

Projektowanie niezawodnościowe z wykorzystaniem kilku strategii utrzymania

Wang Z., Huang H. Z., Du X.

Eksploatacja i Niezawodność

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2009

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nr 4

37-44

PL

Tradycyjna optymalizacja projektowania niezawodnościowego (RBDO) minimalizuje funkcję celu opisującą koszty w zależności od ograniczeń niezawodności. Ograniczenia niezawodności oparte są na modelach fizycznych, takich jak symulacja z wykorzystaniem metody elementów skończonych, których używa się do określania stanu komponentu lub systemu. Stąd niezawodność oznacza tu tzw. niezawodność fizyczną. Ograniczenia niezawodności są zazwyczaj statyczne i nie wyjaśniają problemów związanych z cyklem życia produktu. W niniejszej pracy zaproponowano kilka modeli optymalizacji projektowania niezawodnościowego wykorzystujących kilka strategii utrzymania. Koszt cyklu życia produktu w omawianych modelach został zminimalizowany przy jednoczesnym spełnieniu wymogów niezawodności i dostępności podczas cyklu życia produktu. Do obliczenia czasowo zależnej niezawodności wykorzystano metodę analizy niezawodności pierwszego rzędu (FORM). Możliwość praktycznego wykorzystania proponowanych modeli zilustrowano przykładem.

EN

Traditional reliability-based design optimization (RBDO) minimizes a cost-type objective function subject to reliability constraints. The reliability constraints are based on physical models, such as finite element simulation, which are used to specify the state of a component or a system. Hence the reliability is the so-called physical reliability. The reliability constraints are usually static without accounting for product lifecycle issues. In this work, several reliability-based design optimization models incorporating several maintenance policies are proposed. The product lifecycle cost is minimized while the constraints of product lifecycle reliability or availability are satisfied. The First Order Reliability Method (FORM) is employed to calculate the time dependent reliability. An engineering example is used to illustrate the proposed models.