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船舶转向过程中速度下降问题的研究 被引量:13
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作者 李宗波 张显库 贾云 《航海技术》 2008年第3期2-4,共3页
随着大型船舶的数量不断增长,船舶转向过程中的速降问题已引起人们的重视。戴维逊、Schoenherr等学者绘制了速降系数曲线图或给出了速降估算公式,但只能用于估算定常回转阶段速度V与转向前速度V0之比,对于船舶进入定常回转之前的过渡阶... 随着大型船舶的数量不断增长,船舶转向过程中的速降问题已引起人们的重视。戴维逊、Schoenherr等学者绘制了速降系数曲线图或给出了速降估算公式,但只能用于估算定常回转阶段速度V与转向前速度V0之比,对于船舶进入定常回转之前的过渡阶段的速度下降情况无法估算。本文把船舶的速降系数表征为船舶旋回性指数K′、船舶施加的舵角!以及航向改变量Δ"的函数关系,实现了对转向全过程的速降估算。以超大型油轮OPALIA号为例进行了速降的预报,取得了理想的效果,预报误差最大为14.6%,最小为0.3%。这表明,用多元回归分析的方法实现对船舶整个转向过程中速降的预报具有一定的可行性。 展开更多
关键词 船舶 速降系数 操纵性指数 回转试验 多元回归分析
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船舶转向过程中速度下降问题的研究
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作者 汪衡 《科技风》 2015年第13期31-31,共1页
随着科学技术的发展,科技在船舶制造行业的应用逐渐扩大,大型船舶的产量也在不断地增长。然而,船舶在转向时,速度下降的问题仍然普遍存在。已有的关于船舶转向中速降问题的研究,只能估算出定常回转阶段的速度比,而无法估算出定常回转前... 随着科学技术的发展,科技在船舶制造行业的应用逐渐扩大,大型船舶的产量也在不断地增长。然而,船舶在转向时,速度下降的问题仍然普遍存在。已有的关于船舶转向中速降问题的研究,只能估算出定常回转阶段的速度比,而无法估算出定常回转前过度段的速降情况。本文对国外知名学者戴维逊和Schoenher在这方面的研究情况进行了介绍,并对船舶转向时速降系数展开了研究。 展开更多
关键词 船舶转向 度下 速降系数
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Surface mining subsidence control based on grouting-recovery ratio theory 被引量:1
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作者 WANG Su-hua FU Zhi-liang GAO Yan-fa 《Journal of Coal Science & Engineering(China)》 2010年第2期135-139,共5页
From an analysis of the relationships of grouting coefficients under the conditions of grouting reducing subsidence, it is concluded that the reducing subsidence rate is in direct proportion to the grouting-recovery r... From an analysis of the relationships of grouting coefficients under the conditions of grouting reducing subsidence, it is concluded that the reducing subsidence rate is in direct proportion to the grouting-recovery ratio, and its proportional coefficient depends on the coefficient of reducing subsidence and collapsing coefficient.The coefficient for reducing subsidence volume φ=ΔV/V_(ash) is related to overburden lithology.The coefficient for reducing subsidence volume φ is always larger than 1.This improves the reducing subsidence rate,the grouting-recovery ratio, and the coefficient for reducing subsidence volume, which can maximize the control of surface subsidence. 展开更多
关键词 coefficient for reducing subsidence volume collapsing volume coefficient grouting-recovery ratio fly ash
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General formulas for drag coefficient and settling velocity of sphere based on theoretical law 被引量:3
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作者 Yang Hongli Fan Minqiang +1 位作者 Liu Airong Dong Lianping 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2015年第2期219-223,共5页
The settlement of particles is of great importance in many areas. The accurate determination of drag coefficient and settling velocity in wide Reynolds number (Re) range remains a problem. In this paper, a series of... The settlement of particles is of great importance in many areas. The accurate determination of drag coefficient and settling velocity in wide Reynolds number (Re) range remains a problem. In this paper, a series of new formulas for drag coefficient of spherical particles based on theoretical laws, such as the Stokes law, the Oseen law, and the Goldstein law, were developed and fitted using 480 groups of experimental data (Re 〈 2 × 10^5). The results show that the 2nd approximation of a rational function containing only one parameter can describe Co-Re relationship accurately over the whole Re range of 0-2× 10^5. The new developed formulas containing five parameters show higher goodness over wide Re range than presently existing equations. The introduction of the Oseen law is helpful for improving the fitting goodness of the empirical formulas. On the basis of one of the Oseen-based Co-Re formulas giving the lowest sum of squared relative errors Qover the whole Re range (Re 〈 2 × 10^5), a general formula for settling velocity ut based on dimensionless parameters was proposed showing high goodness. 展开更多
关键词 Sphere Drag coefficient Settling velocity Reynolds number Theoretical equation
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A Battery Life-Cycle Estimation Method Based on Degradation Test Data
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作者 Takuya Shimamoto Ryuta Tanaka Kenji Tanaka 《Journal of Energy and Power Engineering》 2014年第4期709-715,共7页
LiB (lithium-ion battery) has become serious concern for energy management systems, especially in Japan, where the argument on a nuclear power plant problem is active. Including reuse of LiB, long-term use is expect... LiB (lithium-ion battery) has become serious concern for energy management systems, especially in Japan, where the argument on a nuclear power plant problem is active. Including reuse of LiB, long-term use is expected, however, method to ensure LiB life has not been developed thus the users of LiB are forced to accept the uncertainty of LiB life. Therefore this study suggests an evaluation method for LiB life using degradation experimental data. This method has three elements, defining indexes, preparing degradation speed database from the result of experiment, and setting up the use patterns of LiB. In order to be usable under non-experimental conditions, degradation speed database has the data in all conditions by complementing the experimental result. Finally, this evaluation model was verified by comparing model estimates and the experimental measurements. 展开更多
关键词 Lithium-ion battery estimation method life-cycle estimation data analysis.
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