Wyniki wyszukiwania - Biblioteka Nauki

1

A systematic approach for soloving the great circle track problems based on vector algebra

100%

Chen C.-L.

Polish Maritime Research

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2016

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tom 23

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nr 2

EN

A systematic approach, based on multiple products of the vector algebra (S-VA), is proposed to derive the spherical triangle formulae for solving the great circle track (GCT) problems. Because the mathematical properties of the geometry and algebra are both embedded in the S-VA approach, derivations of the spherical triangle formulae become more understandable and more straightforward as compared with those approaches which use the complex linear combination of a vector basis. In addition, the S-VA approach can handle all given initial conditions for solving the GCT problems simpler, clearer and avoid redundant formulae existing in the conventional approaches. With the technique of transforming the Earth coordinates system of latitudes and longitudes into the Cartesian one and adopting the relative longitude concept, the concise governing equations of the S-VA approach can be easily and directly derived. Owing to the advantage of the S-VA approach, it makes the practical navigator quickly adjust to solve the GCT problems. Based on the S-VA approach, a program namely GCTPro_VA is developed for friendly use of the navigator. Several validation examples are provided to show the S-VA approach is simple and versatile to solve the GCT problems

2

Piecewise reliability-dependent hazard rate for composites under fatigue loading adjustment

63%

Chen C.-L. , Wang K.-S.

Journal of Theoretical and Applied Mechanics

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2012

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tom Vol. 50 nr 1

231-250

EN

Based on the derived transition period and reliability drop, this paper proposes a method of piecewise combination of the reliability-dependent hazard rate function named (eocp) model to describe the dynamical reliability in a two-stage fatigue loading process. First, the parameters eo, c, p are fitted through simulated failure data under various constant- amplitude cyclic stresses. The reliability of the high-low loading process is described piecewise with the corresponding values of (eo, c, p) for each respective stress level, and maintains Ra in the transition period while Ra denotes the reliability at which the stress level changes. The reliability of the low-high process is determined by subtracting the portion of reliability drop at Ra from the piecewise fitted curves. The proposed reliability behavior is verified successfully. The linear damage sum is found to be larger than unity for the high-low loading, and on the contrary for the low-high cases. A larger difference between the stress level changed results in larger deviation of damage sum from unity, especially when Ra near 0.9.

PL

W oparciu o wyznaczony okres przejściowy i spadek niezawodności, artykuł prezentuje metodę określania funkcji ryzyka uszkodzenia kawałkami zależnej od poziomu niezawodności, zwanej (eocp) i służącej do modelowania dynamicznej niezawodności dla dwustanowych procesów obciążania zmęczeniowego. Na poczatku, parametry eo, c, i p dopasowano do danych otrzymanych w drodze symulacji uszkodzeń pod wpływem działania cyklicznych naprężeń o kilku stałych amplitudach. Niezawodność dla obciążeń przechodzących od dużej amplitudy do małej opisano kawałkami zależnymi od poziomu przykładanych naprężeń i odpowiadającymi im wartościami eo, c, i p. Wynosi ona Ra w okresie przejściowym, gdzie Ra jest niezawodnością, przy której poziom naprężeń jest zmieniany. Niezawodność przy obciążeniu rosnącym wyznaczono, odejmując część jej spadku przy Ra od kawałkami dopasowanych krzywych. Zaproponowany sposób opisu niezawodności sukcesywnie weryfikowano. Zaobserwowano, że liniowa suma uszkodzeń przekracza jedność dla scenariusza obciążeń stopniowo malejących i nie osiąga tej wartości w przypadku przeciwnym. Większe różnice w poziomach obciążeń skutkowały w większych odstępstwach liniowej sumy uszkodzeń od jedności. Szczególnie duże zauważono dla Ra = 0.9.

3

New computational approaches to determining the astrological vessel position based on the Sumner line

51%

Chen C.-L. , Hsu T.-P. , Weng G.-Y.

Polish Maritime Research

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2014

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tom 21

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nr 4

EN

In this paper two new approaches are developed to calculate the astronomical vessel position (AVP). Basically, determining the AVP is originated from the spherical equal altitude circles (EACs) concept; therefore, based on the Sumner line’s idea, which implies the trial-and-error procedure in assumption, the AVP is determined by using the two proposed approaches. One consists in taking the great circle of spherical geometry to replace the EAC to fix the AVP and the other implements the straight line of the plane geometry to replace the EAC to yield the AVP. To ensure the real AVP, both approaches choose the iteration scheme running in the assumed latitude interval to determine the final AVP. Several benchmark examples are demonstrated to show that the proposed approaches are more accurate and universal as compared with those conventional approaches used in the maritime education or practical operations

4

Graphical method for great circle routes

51%

Hsu T.-P. , Chen C.-L. , Hsieh T.-H.

Polish Maritime Research

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2017

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tom 24

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nr 1

EN

A great circle route (GCR) is the shortest route on a spherical earth model. Do we have a visual diagram to handle the shortest route? In this paper, a graphical method (GM) is proposed to solve the GCR problems based on the celestial meridian diagram (CMD) in celestial navigation. Unlike developed algebraic methods, the GM is a geometric method. Appling computer software to graph, the GM does not use any equations but is as accurate as using algebraic methods. In addition, the GM, which emphasizes the rotational surface, can depict a GCR and judge its benefit

5

Salmonella-infected aortic aneurysm: investigating pathogenesis using Salmonella serotypes

38%

Chu C. , Wong M. Y. , Chiu C.-H. , Tseng Y.-H. , Chen C.-L. , Huang Y.-K.

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tom 68

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nr 4