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1
Content available Study on striking ship with loading impact on the performance of the double hull oil tanker collision
Wu W., Yang Y., Zhang J., Lu J.
Polish Maritime Research
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2018
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S 2
42--48
EN
Due to the great danger of the collision of oil tankers, lots of research on the collision of oil tankers has been carried out. But, at present, the research on the collision of oil tankers mainly focuses on the loading condition of the struck ship, ignores the impact on the loading condition of the striking ship. However, during the actual oil tanker collision, the striking ship is generally in the state of loading. Therefore, it is necessary to carry out the analysis of the impact of the loading condition of the striking ship on the collision damage of the oil tanker. In this paper, the effect of striking ship with loading on the impact performance of the side structure during the collision of the cargo double hull oil tanker has been investigated. The ship collision model was established by using the finite element software ANSYS/ LS-DYNA which is based on 7000 tons of double hull oil tankers. Based on the analysis of the collision force, impact of striking speed changes, impact of striking deep changes and structural energy absorption during the collision process, the influence of the striking ship with loading on the damage mechanism and the impact performance of the double shell oil ship side structure was expounded. The results show that the influence of the striking ship with loading can be great to the damage to side hull during the research of the collision performance of the oil tanker.
2
Content available Progressive collapse test of ship structures in waves
Pei Z., Xu T., Wu W.
Polish Maritime Research
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2018
|
S 3
91--98
EN
The external loads and structural ultimate strength are two important aspects for the safety of ship hull girder. It may collapse in case the structural capacity is less than the external forces in extreme seas. In the present research, progressive collapse test is performed to investigate the collapse mechanism of ship structure in waves. External load with time history and corresponding structural collapse behavior are measured and discussed to demonstrate the interaction of fluid and structures.
3
Content available Development of “4E” levelriver-sea-going ship
Pei Z., Yuan Q., Wu W.
Polish Maritime Research
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2018
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S 3
84--90
EN
In order to effectively promote the construction of the Yangtze River economic belt, it has become China’s national strategy to vigorously develop the river-sea-going transportation. In the present paper, theoretical analysis, numerical simulation and model test are combined together to develop flat-type river-sea-going ship which is characterized with larger loading capacity, lower fuel consumption, better performance on energy-saving and environmental-friendly, excellent economy and higher transportation efficiency. Key technologies on hydrodynamic performance, structural safety, energy-saving technology and green ship technology are investigated to develop the river-sea-going ship. The developed “4E” level ship has great significance to the implementation of national strategic deployment.
4
Content available Tensile-tensile Fatigue Behavior of Multi-axial Warp-knitted Reinforced Composite
Gao X., Tao N., Chen S., Wang L., Wu W.
Fibres & Textiles in Eastern Europe
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2018
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Vol. 26, no. 1 (127)
73--80
EN
An experimental study was carried out on the fatigue behaviour of multi-axial warp-knitted fabric composites. Composite samples reinforced with multi-axial warp-knitted fabric/matrix were manufactured by the vacuum-assisted resin transfer moulding method. Tensile-tensile fatigue cycling was carried out at different load levels, and S-N curves, tensile stress-strain curve and stiffness degradation of the multi-axial composite samples were obtained. Finally post-fatigue tensile tests were done at a stress level of 75%, at the stages of 1/3N and 2/3N, and the equivalent residual strength and stiffness degradation were obtained.
PL
Dokonano oceny właściwości mechanicznych i zmęczeniowych kompozytowych dzianin wieloosiowych. Kompozyty wzmocnione dzianiną wieloosiową wytworzono przy zastosowaniu próżniowej metody formowania. Dokonano oceny zmęczenia materiału i właściwości wytrzymałościowych przy różnych poziomach obciążenia. Przedstawiono krzywe S-N, krzywą naprężenie-odkształcenie i degradację sztywności wieloosiowych próbek kompozytowych. Wykonano również testy zmęczenia materiału przy poziomie naprężenia 75%, w etapach 1/3N i 2/3N. Omówiono równoważną wytrzymałość szczątkową i degradację sztywności kompozytowych dzianin wieloosiowych.
5
Content available Towards the building information modeling-based capital project lifecycle management in the luxury yacht industry
Liu F., Chen C., Wu W.
Polish Maritime Research
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2017
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S 3
41--48
EN
It will be a new approach that BIM’s capital project lifecycle management (CPLM) applied to the yacht industry. This paper explored the feasibility of applying the principles and rationales of BIM for capital project lifecycle management in luxury yacht design, engineering, fabrication, construction and operation. The paper examined the premises and backbone technology of BIM. It then evaluated leading naval engineering and shipbuilding software applications and their development trends from the functional lens of BIM. To systematically investigate a BIM-based approach for capital project lifecycle management (CPLM) in the luxury yacht industry, the paper proposed and outlined an implementation framework. A case study and a student competition use case were discussed to delineate the core constituents and processes of the proposed framework. The case of BIM was reviewed. Through the domestic custom luxury yacht design and prototyping student competition, the application of this framework in educational research is demonstrated and the initial quantitative assessment of the framework is carried out. Conclusions: a BIM-based CPLM implementation framework can help the luxury yacht industry capitalize on the global transformation to an information-centric and data-driven new business paradigm in shipbuilding with integrated design, manufacturing and production.
6
Content available An efficient connected dominating set algorithm in WSNs based on the induced tree of the crossed cube
Zhang J., Xu L., Zhou S. M., Wu W., Ye X.
International Journal of Applied Mathematics and Computer Science
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2015
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Vol. 25, no. 2
295--309
EN
The connected dominating set (CDS) has become a well-known approach for constructing a virtual backbone in wireless sensor networks. Then traffic can forwarded by the virtual backbone and other nodes turn off their radios to save energy. Furthermore, a smaller CDS incurs fewer interference problems. However, constructing a minimum CDS is an NP-hard problem, and thus most researchers concentrate on how to derive approximate algorithms. In this paper, a novel algorithm based on the induced tree of the crossed cube (ITCC) is presented. The ITCC is to find a maximal independent set (MIS), which is based on building an induced tree of the crossed cube network, and then to connect the MIS nodes to form a CDS. The priority of an induced tree is determined according to a new parameter, the degree of the node in the square of a graph. This paper presents the proof that the ITCC generates a CDS with a lower approximation ratio. Furthermore, it is proved that the cardinality of the induced trees is a Fibonacci sequence, and an upper bound to the number of the dominating set is established. The simulations show that the algorithm provides the smallest CDS size compared with some other traditional algorithms.
7
Content available remote Influences of Al, Mg, and K on Calculating Concentrations of Other Formation Elements and Their Corrections in Geochemical Logging
Wu W., Tong M., Niu W., Luo L.
Acta Geophysica
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2015
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Vol. 63, no. 2
451--467
EN
In geochemical logging, the standard capture gamma-ray spectra of Al, Mg, and K have no distinct characteristic energy peaks. This feature easily influences the spectral bands of characteristic peaks of other elements and thus affects the accuracy of calculating their concentrations. To study this influence, we constructed a model formation containing Al, Mg, and K, and employed the Monte Carlo N Particle Transport Code (MCNP) program to simulate their capture spectra. The results indicate that the calculated dry weights of Si are almost free from the influences of Mg, K, and Al. The ones of Ca and Fe are influenced, but only to a minor extent. The dry weight of S is concurrently influenced. Specifically, the K concentration causes S concentration to deviate significantly from its real concentration. By correcting for such influences, we can obtain relatively accurate values. Data processing for a real well validates the finding that Mg, Al, and K in the formation influence the precision of calculation of other elements and also testifies to the effectiveness of the correction method.
8
Content available remote Data-driven Valued Tolerance Relation Based on the Extended Rough Set
Wang G., Guan L., Wu W., Hu F.
Fundamenta Informaticae
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2014
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Vol. 132, nr 3
349--363
EN
The classical rough set theory is based on the conventional indiscernibility relation. It is not very good for analyzing incomplete information. Some successful extended rough set models based on different non-equivalence relations have been proposed. The valued tolerance relation is such an extended model of classical rough set theory. However, the general calculation method of tolerance degree needs to know the prior probability distribution of an information system in advance, and it is also difficult to select a suitable threshold. In this paper, a data-driven valued tolerance relation (DVT) is proposed to solve this problem based on the idea of data-driven data mining. The new calculation method of tolerance degree and the auto-selection method of threshold do not require any prior domain knowledge except the data set. Some properties about the DVT are analyzed. Experiment results show that the DVT can get better and more stable classification results than other extended models of the classical rough set theory.
9
Content available Efficiency comparison between the LLCL and LCL-filters based single-phase grid-tied inverters
Wu W., Huang M., Blaabjerg F.
Archives of Electrical Engineering
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2014
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Vol. 63, nr 1
63-79
EN
An LLCL-filter is becoming more attractive than an LCL-filter as the interface between the grid-tied inverter and the grid due to possibility of reducing the copper and the magnetic materials. The efficiency of the LLCL-filter based single-phase grid-tied inverter also excites interests for many applications. The operation of the switches of the VSI is various with different modulation methods, which lead to different efficiencies for such a single-phase grid-tied inverter system, and therefore important research has been carried out on the effect of the choice of PWM schemes. Then power losses and efficiencies of the LLCL-filter and the LCL-filter based single-phase grid-tied inverters are analyzed and compared under the discontinuous unipolar, the dual-buck and the bipolar modulations. Results show that the efficiency of LLCL-filter based inverter system is higher than the LCL- filter based independent on the modulation method adopted. Experiments on a 2 kW prototype are in good agreement with results of the theoretical analysis.
10
Content available Analiza niezawodnościowa mechanicznego elementu wibracyjnego z wykorzystaniem teorii zbiorów rozmytych
Wu W., Huang H. Z., Wang Z. L., Li Y. F., Pang Y.
Eksploatacja i Niezawodność
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2012
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Vol. 14, No. 2
130-134
PL
Tradycyjna analiza niezawodnościowa wibracyjnego elementu mechanicznego bierze pod uwagę jedynie losowość drgań, rzadko zaś wyjaśnia mogącą występować rozmytość. Taka analiza nie odpowiada zatem praktyce inżynierskiej. Opierając się na teorii drgań mechanicznych, w niniejszym artykule zaproponowano nowatorskie podejście w ramach teorii rozmytej niezawodności, które łączy rozmytą ocenę kompleksową oraz teorię zbiorów rozmytych. Rozmytej oceny kompleksowej użyto do optymalizacji rozmytych czynników analizy niezawodnościowej elementu wibracyjnego. W celu porównania efektywności proponowanego podejścia z efektywnością podejścia tradycyjnego przedstawiono dwa przykłady z dziedziny inżynierii. Wyniki pokazują, że proponowane podejście jest lepsze od tradycyjnego ze względu na możliwość objęcia w problemach inżynierskich czynników rozmytych.
EN
The conventional reliability analysis of mechanical vibration component only considers the randomness of vibration but rarely for the fuzziness that may exist. It is therefore difficult to be consistent with the engineering practices. Based on the mechanical vibration theory, a novel fuzzy reliability approach by integrating the fuzzy comprehensive evaluation and fuzzy set theory is proposed in this paper. The fuzzy comprehensive evaluation is used to optimize the fuzzy factors of the reliability analysis of vibration component. With the aim of comparing the performance of the proposed approach with the conventional approach, two engineering examples are presented. The results demonstrate that the proposed approach is better than the conventional approach for its capability of covering fuzzy factors in the engineering problems.
11
Content available remote Leading edge skewed-swept diagonal compressor rotor and numerical analysis on its internal flow mechanism
Zhou B., You B., Wu W., Wu K-Q.
TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk
|
2009
|
Vol. 13, No 1-2
33-43
EN
The structure of each part of a diagonal compressor directly affects its overall performance and internal flow. We introduce the Reynolds-averaged Navier-Stokes flow simulation for unit calculation on the whole system including a diagonal impeller, a vaneless diffuser and a volute. By analyzing different flow chromatograms of specific sections, we can compare the configuration of three types of diffusers and volutes and the meridian flow status of the corresponding diagonal compressors which serves as a basis for the impeller flow path as well as for its matching designs. Considering the interference between the rotor and the upstream and downstream stillness body, this thesis analyzes how the vaneless diffuser meridian flow path, the volute flow path and its section secondary flow affect the upstream rotor flow. Both the calculation and experimental data on the rotor outlet are compared, as well as the calculated numerical value of the meridian plane streamline distribution and the diffuser velocity distribution, upstream and downstream, coincides with the designed numerical value. Without changing the conventional quasi-three-dimensional design system, the thesis applies the annulus wall boundary layer theory and the velocity distribution diagram to sweep and skew the leading edge of the airfoil. A performance test shows that the leading edge skewed-swept diagonal rotor can better improve the stall characteristic in a low flow rate area and expand the surge margin, compared with conventional diagonal rotor. It can also efficiently restrain the low-momentum fluid conglomeration near the wall region and reduce the secondary flow loss by sweeping and skewing the blade properly. The purpose of the thesis is to make a contribution to optimizing the overall structure design of diagonal compressors and to study further the complex internal flow between the leading edge skewed-swept diagonal rotor and the cover.
12
Content available remote A novel linear observer of three phase converter with measuring average DC link current
Sun X., Chen Z., Wang B., Wu W.
Przegląd Elektrotechniczny
|
2006
|
R. 82, nr 2
96-100
EN
This paper deals with the estimation problem in a three-phase converter using a linear observer. In general, most of the schemes used to control the three phase voltage source converter assume the exact full state information provide by a set of sensors. However, from a practical point of view, it is useful to explore the possibility of reducing the number of sensors, or even using the soft sensors as back up for security purposes. On the basis of some structural properties of the converter, it can be mathematically shown that it is possible to design such estimators. In this light, a linear mathematical model observer with the average dc current is proposed. Simulations and experiment results are shown to demonstrate the performances of these soft sensors.
PL
Artykuł ten jest poświęcony problemowi estymacji z użyciem obserwatora liniowego w trójfazowym przekształtniku. Na ogół w większości schematów regulacji trójfazowego przekształtnika napięcia zakładana jest dokładna informacja o wszystkich zmiennych stanu dowstarczona przez zestaw czujników pomiarowych. Jednakże z praktycznego punktu widzenia użyteczne jest badanie możliwości redukcji liczby czujników, a nawet użycia wielkości estymowanych do celów zabezpieczeniowych. Opierając się na pewnych właściwościach struktury przekształtnika można wykazać matematycznie, że możliwe jest zaprojektowanie takich estymatorów. W świetle tego został zaprezentowany matematyczny model linowego obserwatora ze średnią wartością prądu dc. W celu przedstawienia osiągów tych estymatorów zostały pokazane wyniki symulacyjne oraz eksperymentalne.
13
Content available Comparison of five depth-averaged 2-d turbulence models for river flows
Wu W., Wang P., Chiba N.
Archives of Hydro-Engineering and Environmental Mechanics
|
2004
|
Vol. 51, nr 2
183-200
EN
In this study, five depth-averaged 2-D turbulence models for river flows, including the depth-averaged parabolic eddy viscosity model, modified mixing length model, standard k-e turbulence model, non-equilibrium k-e turbulence model and re-normalized group (RNG) k-e turbulence model, are compared in the simulation of flows around a spur-dyke, in a sudden-expanded flume and in two natural rivers. It is shown that in the two field cases where the channel geometries are simple, all five models can give generally good predictions for the main flow features. However, in the two laboratory cases where the channel geometries are complex, differences have been found among these models. The depth-averaged parabolic eddy viscosity model over-predicts the recirculation flows behind the spur-dyke and the flume expansion. The modified mixing length model gives better prediction than the depth-averaged parabolic model. The standard k-e turbulence model predicts well for the recirculation flow in the sudden-expended flume, but under-predicts the length of recirculation zone behind the spur-dyke, while the non-equilibrium and RNG k-e turbulence models provide good results for both laboratory cases.
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