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991.
舰船辅机是舰船重要的配套设备,如何通过推进可靠性工作来提高舰船辅机的质量与可靠性显得尤为关键。本文从可靠性策划、设计、分析、数据统计等四方面详细阐述了开展舰船辅机可靠性工作的方法。 相似文献
992.
Atsuo Maki Jun Arai Tatsuhiro Tsutsumoto Keisuke Suzuki Yoshiki Miyauchi 《Journal of Marine Science and Technology》2016,21(2):344-358
It is well known that a decrease in ship resistance may be achieved due to the installation of a stern flap. Therefore, so far, a considerable amount of research on stern flaps has been conducted. Previous research has demonstrated that the primary mechanism by which a stern appendage reduces resistance is a change in the pressure distribution over the aft body of the hull, and secondly through effects on the running attitude, near and far field wave generation, and local transom flow among other phenomena. However, the change in pressure distribution is influenced by the other components. Hence, there is still room for argument about the relative contribution of each component to the pressure distribution. Therefore, as the first step of the research, by conducting the model experiment in towing tank and CFD (Computational Fluid Dynamics) analysis, we examined the effect of running attitudes and wave making at the after portion of the hull on resistance reduction. As a result, it is concluded that a flap affects a change in the wave generated at the transom part and it could lead to a decrease in wave-making resistance. 相似文献
993.
Tendons vertically moor Tension-Leg Platforms (TLPs), thus, a deep understanding of physical tendon stresses requires the determination of the total axial deformation of the tendons, which is a combination of the heave, pitch, and surging responses. The vertical motion of the lateral sides of the TLP is coupled with surge and constitutes a portion of the pitch motion. Tendons are connected to the sides of the TLP; hence, the total displacement of the lateral sides is related to the total deformation of the tendons and the total axial stress. Therefore, investigating the total vertical response at the sides of the TLP is essential. The coupling between various degrees of freedom is not considered in the Response Amplitude Operator (RAO). Therefore, in frequency domain analysis, the estimated vertical RAO is incomplete. Also, in the time domain, only the heave motion at the center of TLP is typically studied; this problem needs to be addressed. In this paper, we investigate the portion of the pitch motion in the vertical response at the sides of the TLP in both the frequency and time domains. Numerical results demonstrate a significant effect of the pitch motion in the vertical motion of the edges of the TLP in some period ranges. 相似文献
994.
995.
LI Qing-fen ZHENG Wei SHU Hai-sheng 《船舶与海洋工程学报》2005,4(3):1-4
In part I and II of this series, experimental investigation in both EPFM and LEFM had been discussed. In this part, further theoretical analysis is given. The theoretical development of Two Parameter Fracture Mechanics by Hancock etc, has rationalized our experimental results. This method can be applied to engineering practice, and will allow the advantage of enhanced toughness for specimens with low levels of constraint to be taken into account for defect assessment. 相似文献
996.
LIU Yu-jun ZHU Xiu-li JI Zhuo-shang 《船舶与海洋工程学报》2005,4(3):13-17
The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method. 相似文献
997.
TAN Zhi-yong MU Yong ZHENG Hong-tao 《船舶与海洋工程学报》2005,4(3):42-46
A finite-rate method is used to simulate the three-dimensional combustion process in a plasma generator with CH4 as the fuel. The simulation was run with RNG k-ε model to simulate turbulence, with eddy-dissipation-concept (EDC) model to simulate the combustion and with discrete ordinates model to simulate radiation. The numerical results show that the flow field characteristics and the parameter distributions are under the condition of rich fuels, and these results provide valuable information when optimizing the plasma generator design and organizing its flow fields. 相似文献
998.
The secure socket layer/ transport layer security(SSL/TLS) handshake protocol uses public key cryptographic algorithms such as RSA for key establishment. Typically, public key cryptographic algorithm is computational intensive due to the modular multiplications. Therefore, SSL/TLS servers often become swamped while performing public key decryptions when the simultaneous requests increase quickly. A batch RSA decryption algorithm was proposed. The novel algorithm provides the reasonable response time and optimizes server performance significantly. The decryption speedup is proportional to the batch size b, for instance, the speedup factor is 4, while in Shacham's scheme the acceleration rate is only 2.5 when b = 4. 相似文献
999.
Ryuichi Kitamura 《Transportation》2009,36(6):745-762
(Added to the original text) A fundamental solution to the issue of congestion cannot be reached without addressing the question
of life-style. This paper reviews the definitions of life-style found in the literature, and identifies variables that have
been commonly associated with life-style. Using US consumer expenditure data, life-styles are analyzed longitudinally (examining
trends during the 1953–1983 time frame) and cross-sectionally (comparing segments of the population stratified by income,
life-cycle stage, and age), and likely relationships to travel behavior are noted. The usefulness of existing empirical findings
to long-range forecasting is explored by speculating on shifts of behavioral units across life-style segments, and on shifts
in the behavioral patterns within each life-style segment. 相似文献
1000.
Partial safety factors must be evaluated precisely for the given target reliability index to ensure the certain level of structural
reliability due to uncertain factors. The current studies of partial safety factors do not consider human error in construction
for structural reliability. A mathematically model should be improved to simulate the partial safety coefficient concerned
uncertainty factors which concern the effect of human error in construction. We employ the contaminated distribution to obtain
the realistic mean value and standard variance of variable of structural parameters which coexist with random error human
error. The reasonable partial safety coefficient can be calculated based on the realistic value of structural parameters concerned
the effects of random error and gross error. 相似文献