Experimental investigation on a cabin-suspended catamaran in terms of motion reduction and wave energy harvesting by means of a semi-active motion control system     

《Applied Ocean Research》2019

A novel concept catamaran equipped with a suspended cabin, named Wave Harmonizer Type 4 (WHzer-4), is proposed and evaluated. The mass-spring-mass system is constructed by mounting four sets of suspensions in-between the cabin and the twin-hull. Two sets of dual motor/generators (M/Gs) are attached on the center beam of the cabin's deck fore and aft. Each shaft-end of the dual M/Gs is connected to the twin-hull through a rack-pinion gear unit. In this way the vertical relative motion between the cabin and the twin-hull can be transferred into the rotational motion of the M/Gs, and vice versa. A semi-active motion control system, which contains a proportional-integral (PI) controller, is designed and applied to each of the dual M/Gs for the aim of absorbing wave energy under the condition of suppressing the local vertical velocity of the cabin as much as possible. A 1/5 scale model ship with a length of 1.6 m is built, and a forced-oscillation bench test is implemented to validate the performance of the control system. Then, a series of towing tank tests is carried out in regular head waves. The heave and pitch responses of the cabin, those of the twin-hull and the corresponding wave energy capture width ratio (CWR) at five control scenarios and two reference scenarios are investigated. Discussion on the results of the tank test shows that the motion reduction of the cabin and the wave energy harvesting can be achieved simultaneously at a few wave conditions. However, at other conditions, although noticeable amount of wave energy is harvested, motion reduction of the heave and pitch of the cabin could not be obtained at the same time. It is suggested that varying the gain settings of the PI controllers according to the location of the controllers may improve the effectiveness of the proposed control system.  相似文献   

An Automatic Method for Detecting Transients and Variable Sources in AST3 Survey Based on Image Subtraction and Random Forest     

《Chinese Astronomy and Astrophysics》2020,44(1):41-60

AST3-2 (the second Antarctic Survey Telescope) is located in Antarctic Dome A, the loftiest ice dome on the Antarctic Plateau. It produces a huge amount of observational data which require a more efficient data reduction program to be developed. Also the data transmission in Antarctica is much difficult, thus it is necessary to perform data reduction and detect variable and transient sources remotely and automatically in Antarctica, but this attempt is restricted by the unsatisfactory performance of the low power consumption computer in Antarctica. For realizing this purpose, to develop a new method based on the existing image subtraction method and random forest algorithm, taking the AST3-2 2016 dataset as the test sample, becomes an alternative choice. This method performs image subtraction on the dataset, then applies the principle component analysis to extract the features of residual images. Random forest is used as a machine learning classifier, and in the test a recall rate of 97% is resulted for the positive sample. Our work has verified the feasibility and accuracy of this method, and finally found out a batch of candidates for variable stars in the AST3-2 2016 dataset.  相似文献   

基于水资源约束的中国城镇化SD模型与模拟   总被引：1，自引：0，他引：1  

曹祺文  鲍超  顾朝林  管卫华 《地理研究》2019,38(1):167-180

中国城镇化正处于快速发展阶段,尽管经济和社会发展主控要素还在发挥重要作用,但水资源在生产、生活和生态方面发挥主控作用的局面愈益明显。在中国城镇化系统动力学（system dynamics,SD）模型基础上,从水资源供给、需求和水环境等层面将水资源作为主控要素嵌入原有模型中,拓展出基于水资源约束的中国城镇化SD模型,并对水资源利用进行了多情景模拟。结果表明：① 系统存流量和灵敏度检验证明模型模拟效果良好,具有可操作性。② 部门用水效率一定时,产业发展对水资源供需平衡的影响比人口增长更为明显。③ 在实行节水农业、节水工业、高生活需水、高生态环境需水和高再生水利用的综合协调方案中,2050年中国城镇化的发展约共需6789.70亿 m³水资源,基本实现水资源供需平衡。  相似文献   

京津冀夏季强降水下冰云宏微观特征          下载免费PDF全文

郑倩  郑有飞  王立稳  李特  林彤  杜傢义 《干旱区地理》2019,42(1):67-76

根据Aqua MODIS 2级云产品和Cloudsat的2级产品资料，结合降水数据和MODIS L1B级辐射率数据，对发生在京津冀地区夏季的三次强降水过程中冰云的宏微观物理量的特征进行分析，并探究这些物理量和降水强度的关系。结果表明：在水平分布中，强降水过程中降水强度高值区内云相为冰云，冰云云顶高度在8~17 km，冰云粒子有效半径、冰云光学厚度、冰水路径分别最高可达60 μm、 150、 5 000 g?m^-2；冰云光学厚度、冰水路径、冰云云顶高度随降水强度增大而增大。在垂直分布中，冰云主要分布在3.5 km以上，发生强降水站点的冰云为深对流云，冰云粒子有效半径、冰水含量、冰云粒子数浓度分别最高可达150 μm、 3 000 mg?m^-3 、 500 L^-1；冰云粒子有效半径高值区存在于云层中下部，且随高度上升而减小，冰云粒子数浓度高值区存在于云层中上部，且随高度上升而增加，冰水含量高值区则存在于云层中部；冰云粒子有效半径、冰水含量、冰云粒子数浓度在9 km以上随降水强度增大而增大。  相似文献   

深渊着陆器坐底位置的精确测量和反演计算          下载免费PDF全文

陈瀚  丘学林  贺恩远  王元  陈传绪  陈俊 《地球物理学报》2019,62(5):1744-1754

深渊着陆器在下潜过程中,由于受到海流的影响,其坐底位置会偏离投放点,偏离量和偏离方向很难估计,而声学水下定位方法在深渊海区不太适用.通过在海面进行气枪十字放炮作业,利用炮点准确位置和时间信息,以及海底地震仪(Ocean Bottom Seismometer,OBS)记录的直达水波到时,对深渊着陆器的坐底位置进行精确测量可以提供有效定位数据.该方法对采集得到的数据进行预处理,使用蒙托卡洛方法结合最小二乘法,对万泉号着陆器实际坐底位置进行了反演校正,得到三个潜次的位置校正偏移量分别为211m、178m、861m,偏移方向各不相同,校正精度为±20m,比以往的定位精度大为提高.此外,该方法测量确定了三个海底标志物的精确位置,为未来万米无人或载人潜器提供了可靠的水下参考坐标.  相似文献   

Response to the paper by H. Zia,B. Lecampion “Explicit versus implicit front advancing schemes for the simulation of hydraulic fracture growth” (Int. J. Numer. Anal. Methods Geomech., 2019, 43 (6), 1300–1315)     

Aleksandr Linkov 《国际地质力学数值与分析法杂志》2020,44(16):2254-2259

The response presents three comments, which (i) explain theoretical background for the success of the explicit front advancing scheme by Zia and Lecampion (comment 1), (ii) suggest possible extensions (comment 2), and (iii) pay attention on expected limitations of the scheme to be checked by the authors in numerical experiments (comment 3). The response does not intend to present novel results: it is entirely based on known results published in the references cited.  相似文献   

基于混合聚类的岩体结构面优势分组方法     

许扬  张文  符锐  聂振邦  兰志广  陈怀玉  单博 《世界地质》2020,39(1):113-120

提出一种基于凝聚层次法和模糊C均值法的混合聚类法,用于对岩体结构面的优势组划分。该方法将结构面投放到在单位球面上,并使用欧式距离作为极点的相似性度量准则。先剔除结构面数据中的孤值产状,然后用凝聚层次法得到初步聚类结果,并将其作为FCM法的初始聚类中心,最后用FCM法划分优势组。通对人工生成产状样本的分组,验证了该法的正确性。将该方法应用于大藤峡坝址区实测的结构面数据的划分。在实测数据中寻找到两个孤值产状,成功将大藤峡D1y^1-3地层岩体结构面划分为两组,得到了符合实际的分组结果。  相似文献   

东海盆地中、新生代盆架结构与构造演化   总被引：6，自引：0，他引：6  

刘金水  许怀智  蒋一鸣  王军  何新建 《地质学报》2020,94(3):675-691

基于地貌、钻井、岩石测年和地震等资料,分析盆地地层分布、盆架结构、构造单元划分和裂陷迁移规律,结果表明东海盆地由台北坳陷、舟山隆起、浙东坳陷、钓鱼岛隆褶带和冲绳坳陷构成,是以新生代沉积为主、中生代沉积为辅的大型中、新生代叠合含油气盆地;古元古代变质岩系构成了盆地的基底。该盆地不仅是印度-太平洋前后相继的动力体系作用下形成的西太平洋沟-弧-盆构造体系域一部分,而且也是古亚洲洋动力体系作用下形成的古亚洲洋构造域和特提斯洋动力体系作用下形成的特提斯洋构造域一部分,晚侏罗世至早白垩世经历了构造体制转换,盆地格局发生重大变革,早白垩世以前主要受古亚洲-特提斯洋构造体制影响的强烈挤压造山和地壳增厚作用演变为早白垩世以来主要受太平洋构造体制控制的陆缘伸展裂陷和岩石圈减薄作用,经历侏罗纪古亚洲-特提斯构造体制大陆边缘拗陷和白垩纪以来太平洋构造体制弧后裂陷两大演化阶段。白垩纪以来太平洋构造体制的弧后裂陷演化阶段可细分为早白垩世至始新世裂陷期、渐新世至晚中新世拗陷期和中新世末至全新世裂陷期。  相似文献   

非典型周期和气候突变的识别与判定          下载免费PDF全文

秦建国 《水文》2020,40(1):23-28

通过两种新方法分析了无锡站降水年际变化的突变性、周期性等特征,揭示了旱涝演化的自然规律。研究表明,1934、1978、2013年是我国近现代气候突变的临界点,这是旱涝演化的自然选择;无锡站年际降水的观测历史可分成四个特征不同的时段,每个时段节点对应的都是一次气候突变;气候突变会改变年际降水序列的一致性,分段法研究可以大幅度降低模拟难度、提高预测效率。发现并确认了3个气候突变点,实现了超长缺测中断期(13a)旱涝趋势的精确插补,完成了无锡站近百年降雨序列的周期性分析与旱涝趋势预测模拟,研究成果改变了近现代气候历史无法细分的现状。  相似文献   

基于噪声谱比法的内蒙古西部地区台站场地响应研究     

张珂  王鑫  王树波  张红才  宋晓燕 《大地测量与地球动力学》2020,40(6):646-651

利用内蒙古西部12个台站的地脉动噪声数据，采用噪声谱比法研究台站的场地响应情况。分析表明，台站场地响应按曲线形态可分为3类，且可能受地形地貌、局部构造和台基状况等条件影响。对比分析噪声谱比法与Moya方法的场地响应结果发现，场地响应曲线形态基本一致，只有极少数台站存在明显差异。结果表明，内蒙古西部区域大部分台站的台基状况总体较好，场地响应曲线较为平坦，无明显频率放大点。  相似文献