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941.
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943.
The homotopy method is utilized in the present inverse hull design problem to minimize the wave-making coefficient of a 1300 TEU container ship with a bulbous bow. Moreover, in order to improve the computational efficiency of the algorithm, a properly smooth function is employed to update the homotopy parameter during iteration. Numerical results show that the homotopy method has been successfully applied in the inverse design of the ship hull. This method has an advantage of high performance on convergence and it is credible and valuable for engineering practice. 相似文献
944.
利用欧洲中尺度天气预报中心(ECMWF——European Centre for Medium-Range Weather Forecasts)的1979年1月2014年12月逐6 h的ERA-Interim有效波高和10 m风场资料,分析了近36年期间北太平洋海域海浪场和风场的变化特征。结果表明:1)中低纬度的西北太平洋波高有逐年线性递增趋势,大约在0.2~0.6 cm/a,而低纬度的太平洋东北部海域则以-0.4~-0.2 cm/a的趋势减小。2)风速线性变化趋势显著的区域主要集中在太平洋东北部低纬度海域,约以1.0~2.0 cm/(s·a)的速度在增加。而日本岛四周、菲律宾半岛以南等海域大都以-1.0~-0.5 cm/(s·a)的速度减小。3)北太平洋海域波高和风速都具有明显的季节变化特征,两者具有很强的相关性。西风带内有一个个波高超过10 m的风暴圈,其波高受风浪和涌浪的双重作用。这可为航海、海洋工程设计、军事及海洋能开发与利用等方面提供科学依据。 相似文献
945.
以野生草地早熟禾(Poa pratensis)和硬质早熟禾(Poa sphondylodes)为材料,通过人工室内模拟低温逆境胁迫,研究外源一氧化氮(NO)供体亚硝基铁氰化钠(硝普钠,SNP)对低温胁迫下野生早熟禾幼苗生长、渗透调节和抗氧化系统的影响,探讨外源NO提高早熟禾抗寒性的生理机制。结果表明,低温胁迫下:0~700 μmol·L-1浓度范围内,随SNP浓度的增大,两个供试材料的地上生物量和生长速度先增大后减小,相对膜透性、丙二醛(MDA)含量、游离脯氨酸(F-Pro)含量先减小后增大,可溶性糖(SS)和可溶性蛋白(SP)含量先增加后减小,超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性先增强后减弱;高浓度NO产生伤害,低浓度NO则有保护作用;SNP浓度100 μmol·L-1时,膜脂过氧化水平最低,渗透调节物质积累最多,保护酶活性最强,对低温胁迫的缓解效果最佳。硬质早熟禾对低温胁迫下外源NO的缓解较草地早熟禾敏感。 相似文献
946.
To understand implementation of a nationwide sloping farmland soil erosion comprehensive control project during China’s 12th Five-Year Plan we used data collection and expert consultation. We selected 24 indexes across three aspects including project management, engineering construction and implementation benefit and used AHP-grey correlation analysis methods. We found that the scores for engineering construction were greater than 0.65 in most of the provinces, autonomous regions and municipalities. These scores are high and scores for project management and implementation benefit are between 0.45-0.65; however, overall scores are low. The comprehensive evaluation results are normally distributed. The composite scores for Sichuan, Yunnan and Guizhou are 0.71, 0.68 and 0.68 respectively, indicating that the implementation effects are good. The scores for Jilin and Liaoning are 0.38 and 0.42 respectively, indicating that the implementation effects need improvement. Scores for other provinces are between 0.45-0.65 and the effects are medium. The evaluation results show certain zonal rules spatially and the implementation effect in karst regions of Southwest China is the highest, followed by the purple soil region in Southwest China, Loess Plateau region of Northwest China, earth-rock mountain region of North China and red soil hilly region of South China. The implementation effect in the black soil region of Northeast China suggests that improvement is needed in this region. 相似文献
947.
948.
949.
中生代巴彦喀拉-松潘甘孜地体向东昆仑地体斜向俯冲,在东昆仑南缘形成一条巨型的韧性剪切带。剪切带中发育的旋转碎斑、书斜构造、解理阶步、云母鱼、S-C组构、不对称褶皱、雁列脉等宏微观构造,显示剪切带兼具右行和左行的特征,且右行早于左行剪切,但总体以左行剪切为主。对西大滩糜棱岩化花岗岩和小南川未变形花岗岩进行了LA-ICP-MS锆石UPb测年,西大滩岩体侵位于199.3±2.2Ma,小南川岩体形成于196.4±1.3Ma。西大滩与小南川岩体中的锆石为典型的岩浆锆石,其年龄代表了岩体侵位的时代。鉴于2个岩体的变形程度完全不同,东昆仑南缘在199~196Ma之间发生了左行韧性剪切。 相似文献
950.
Feng Xu Chunhe Yang Yintong Guo Lei Wang Zhenkun Hou Haoran Li Xiaoming Hu Tongtao Wang 《Arabian Journal of Geosciences》2017,10(6):141
The experimental work described in this paper was carried out in order to discover more about the effects of bedding planes on wave velocity and acoustic emission (AE) characteristics of shale. Two groups of specimens, which were collected from the Longmaxi shale outcrop in Chongqing, China and cored perpendicular and parallel to the bedding planes, were tested under uniaxial compression, and the wave velocity and AE were monitored. There were obvious differences in the acoustic characteristics of shale with different bedding plane orientations. The experimental results show that (1) the average increasing rates of P- and S-wave velocities were 39.86 and 54.41%, respectively, for the specimen with a load perpendicular to the bedding planes (Y-0). The P-wave velocity and axial strain of specimen show a marked logarithmic relationship. However, the average increasing rates of P- and S-wave velocities were 5.44 and 10.54%, respectively, for the specimen with a load parallel to the bedding planes (Y-90). The good linear relationship between P-wave velocity and axial strain before failure of specimen has been built. Generally, S-wave velocity was more sensitive to axial strain than P-wave velocity. (2) AE characteristics for Y-0 showed that a few signals → quiet period → stable increase → steep increase; for Y-90: quiet period → stable increase → sudden increase → sharp increase. The AE energy for two groups of specimens was concentrated on low and middle of amplitudes (45-80 dB), but the proportion of amplitudes (80–100 dB) and the total counts of AE for Y-0 was 1.95, 2.2 times as much as that for Y-90, respectively. The results preliminarily revealed the effect of bedding orientation on the wave velocity and AE properties of shale and may provide guidance for the improvement of acoustic logging and microseismic monitoring in the field. 相似文献