Analysis of the Gravity-1 Sea Launch System and Technical Features

Sea launch has the characteristics of flexible launching points, high landing area safety, and good economy. In recent years, it has become one of the important launch methods. Since 2019, China has carried out a total of 11 successful sea launches. The Gravity-1(YL-1) sea launch system consists of a launch vehicle system and a sea launch platform. The sea launch program includes roll on/roll off boarding, sea mooring, sea maneuvering, anchoring and positioning, system testing, and formal launch. Through the maiden flight of YL-1, the design and manufacturing technology of large tonnage dedicated launch ship, launch vehicle vertical transfer and roll on/roll off boarding technology, anti-shake technology for sea launch, simple inflatable flexible insulation protective cover technology, and remote wireless measurement and control technology have been fully verified.

TIDAL FEATURES IN THE CHINA SEAS AND THEIR ADJACENT SEA AREAS AS DERIVED FROM TOPEX/POSEIDON ALTIMETER DATA

Some important tidal features of 8 major tidal constituents ( M 2, S 2, K 1, O 1, P 1, Sa, N 2 and K 2 ) in the China Seas and their adjacent sea areas were obtained using six years’ TOPEX/POSEIDON altimeter data. The results showed that the obtained co tidal and co range charts for these major tidal constituents agreed well with those of previous researches using observational data from coastal tidal gauge stations and numerical models.

The variation features of the Antarctic sea ice (Ⅱ)

In this paper, on the basis of the Antarctic sea ice data from 1972 to 1989 issued by the America JointIce Center, the distribution features of the Antarctic sea ice is analyzed, the net sea ice area indexes are calculated,and the long-range variation periods of the sea ice area index are analyzed with the maximum entropy spectrum, finally the distribution pattern of the Antarctic sea ice and its variation features are obtained.According to its spatial distribution feature, the Antarctic Sea ice is divided into three large regions. Region Ⅰ(0°～120°E) is a zonal area which includes the Prydz Bay area, and sea ice area extending from the Weddell Sea,Region Ⅱ (120°E～120°W) mainly includes the Ross Sea area, and Region Ⅲ (120°W～0°) mainly the WeddellSea area. Of all the regions, the ice area in Region Ⅲ is the largest, and that in Region Ⅰ is the smallest.In the Antarctic,the seasonal changes of the sea ice are very obvious, during summer, in February, there isleast sea ice in the Southern Ocean, the net sea ice area (not include the area of open water) is about 3 190 000 km2,during winter, in September, there is most sea ice in the Southern Ocean, the area index is about 16 840 000 km2,nearly 5. 3 times of that in February. The seasonal change of sea ice is one month lag of the changes of the air temperature, but almost synchronous with that of SST.Of all the three regions divided above, there are some points both common and uncommon in their sea icechange cycles, the common features are that there exist one and a half years, one year and ten-months secondaryperiods in all three regions, but their main periods are not the same, they are about 5, 11 and 6 a in Regions Ⅰ,Ⅱ,and Ⅲrespectively. The main periods of the sea ice change in Regions Ⅰand Ⅱ are very close because the ice areaextended eastward from the Weddell Sea ice area of Region Ⅲ is one of the main components of the Region Ⅰ. It isalso worth pointing out that in Region Ⅱ, southward extension of the Pacific Ocean, there exist not only a 11-yerasmain period but also a 2-yeras secondary period, which does not exist in the other two regions.

A study on dynamical features of air-sea coupling waves in the tropics

The dynamical features of air-sea coupling waves and their stabilities in a simple coupled air-sea model in the tropics have been studied with respect to interaction occurring among different types of the free waves in the o-cean and in the atmosphere. It is pointed out that there exist a stable and an unstable air-sea interaction modes in the tropical coupled system , respectively. The propagation of the unstable mode relies greatly on the zonal space scale, i. e. only for wave length ranging from 5 000 km to 10 000 km can the disturbance unstably move slowly eastward. The waves that slowly propagate unstably eastward agree well with the observational facts. Finally,it is also proposed that the interaction between Kelvin wave in one medium and Rossby wave in another medium is a necessary condition for the occurrence of destabilization of the coupled air-sea system in the tropics.

Distribution and Characteristics of Hazardous Geological Features in the Marine Coastal and Offshore Areas of Zhejiang Province, East China Sea

Newly acquired high-resolution shallow seismic profiles(7069 km in length) in the coastal and offshore areas of Zhejiang Province, East China Sea, China, have revealed eight marine hazardous geological features: shallow gas, sand ridges, erosion ditches, scarps, irregular bedrock features, underwater shoals, buried paleo-channels, and submarine deltas. Based on the seismic profiles, we have constructed a marine geological map of these hazardous features. Shallow gas accumulations are common and occur mainly in two separate nearshore regions that cover 4613 and 3382 km^2 respectively. There are also scattered shallow gas accumulations in the offshore area, typically accompanied by paleo-channels that occur mainly in the middle of the study area. Sand ridges, erosion ditches, scarps, and irregular bedrock features are found mainly in the northeast of the study area in association with each other. In the southeastern part of the study area, the sand ridges have a linear form and trend NW–SE, representing the western part of the linear sand ridges in the East China Sea. The maximum slope gradient is 1?, which suggests that this area is prone to landslides. These hazardous marine geological features are important to marine and engineering activities in this region.

Hotspots of seabirds and marine mammals between New Zealand and the Ross Gyre:importance of hydrographic features

This article is part of our long-term study on the quantitative at-sea distribution of the marine "upper trophic levels"—seabirds and marine mammals—in polar ecosystems, aiming at quantifying the factors influencing their distribution as well as detecting possible spatial and temporal changes, with special attention to hydrography and to global climate changes. During an expedition of icebreaking RV Polarstern in February 2010, along the North–South transect between New Zealand and the Ross Gyre, off the Ross Sea, 3200 seabirds belonging to 22 identified pelagic species were recorded during 338 half-hour transect counts. Four major hotspots were identified. These were in Sub-tropical Water off New Zealand(up to 300 birds per count), and at the main Southern Ocean fronts: the Sub-Antarctic Front(up to 240 per count), the Antarctic Front(up to 150 per count) and the Polar Front(up to 200 per count), representing the vast majority of recorded seabirds. The most numerous species in the three frontal zones were: prions—mainly slender-billed Pachyptila belcheri—and Salvin’s albatross Thalassarche [cauta]salvini. The eight more abundant species represented 2650 birds, i.e. more than 80% of the total. A random forest clustering method identified four groups of seabird species occupying similar oceanographic niches.

Statistical study on the spatial - temporal distribution features of the arctic sea ice extent

On the basis of the arctic monthly mean sea ice extent data set during 1953-1984, the arctic region is divided into eight subregions,and the analyses of empirical orthogonal functions, power spectrum and maximum entropy spectrum are made to indentify the major spatial and temporal features of the sea ice fluctuations within 32-year period. And then, a brief appropriate physical explanation is tentatively suggested. The results show that both seasonal and non-seasonal variations of the sea ice extent are remarkable, and iis mean annual peripheral positions as well as their interannu-al shifting amplitudes are quite different among all subregions. These features are primarily affected by solar radiation, o-cean circulation, sea surface temperature and maritime-continental contrast, while the non-seasonal variations are most possibly affected by the cosmic-geophysical factors such as earth pole shife, earth rotation oscillation and solar activity.

Sedimentary Features and Sea-Level Changes Reflected in Drill Holes in the Zhuhai Area

Abstract Experimental examinations and analyses have been made of the sediments from drill holes in the Zhuhai area, Guangdong Province. The studies show that there occurred four transgressions in this area over the historical times. The first transgression occurred at 7500 a B.P., with the maxium sea level up to about 1 m above the present level. The second transgression occurred at 5750 a B.P., with the sea level possibly 4 m higher than the present. The third and fourth transgressions took place at 4650 a B.P. and 2600 a B.P. respectively, which lasted for a long time with multiple fluctuations. The fifth transgression is in process. It could be predicted that the sea level at Zhuhai would rise by 15–20 cm in the coming 50 years.

Underwater Sea Cucumber Target Detection Based on Edge-Enhanced Scaling YOLOv4

Sea cucumber detection is widely recognized as the key to automatic culture.The underwater light environment is complex and easily obscured by mud,sand,reefs,and other underwater organisms.To date,research on sea cucumber detection has mostly concentrated on the distinction between prospective objects and the background.However,the key to proper distinction is the effective extraction of sea cucumber feature information.In this study,the edge-enhanced scaling You Only Look Once-v4(YOLOv4)(ESYv4)was proposed for sea cucumber detection.By emphasizing the target features in a way that reduced the impact of different hues and brightness values underwater on the misjudgment of sea cucumbers,a bidirectional cascade network(BDCN)was used to extract the overall edge greyscale image in the image and add up the original RGB image as the detected input.Meanwhile,the YOLOv4 model for backbone detection is scaled,and the number of parameters is reduced to 48%of the original number of parameters.Validation results of 783images indicated that the detection precision of positive sea cucumber samples reached 0.941.This improvement reflects that the algorithm is more effective to improve the edge feature information of the target.It thus contributes to the automatic multi-objective detection of underwater sea cucumbers.

多特征融合的无人艇视觉小目标鲁棒跟踪

[目的]针对低特征分辨率、相似环境信息引起的无人艇视觉小目标跟踪混淆问题,提出一种多特征融合的连续卷积算子跟踪算法。[方法]首先,采用双三次插值技术,提高多特征图分辨率,实现亚像素级定位;其次,利用特征投影和生成样本空间,提高目标跟踪的效率,避免滤波器过拟合;最后,设计高置信度模型更新策略,解决相似环境信息对滤波器的干扰问题。[结果]结果表明:相较于传统的连续卷积算子跟踪算法,平均成功率提升17.4%,平均距离精度指标提升17.8%,期望平均覆盖率提升5.1%。[结论]该算法法能够处理海洋环境下的小目标跟踪混淆问题,为提升无人艇及海洋机器人的智能感知能力,提供关键技术支撑。

基于快速时频图的海面无人机目标多特征检测

海面无人机(UAV)的检测属于海杂波背景下的小目标检测问题,多特征联合检测是解决此类问题的有效途径。针对已有的时频三特征检测方法在特征提取阶段计算复杂度过大、难以实现实时检测的问题,提出了一种基于快速时频图的海面无人机多特征检测方法。首先,对雷达复回波数据进行分段快速傅里叶变换,将计算得到的多普勒幅度谱沿多普勒维对齐拼接从而构建快速时频图;其次,对快速时频图进行归一化,达到杂波抑制和增强目标回波的目的,并基于归一化的快速时频图提取三种时频特征;然后,利用快速凸包学习算法训练给定虚警概率下的检测判决区域;最后,通过实测UAV数据验证并分析了所提方法的有效性。

黄渤海5处人工鱼礁区浮游生物的群落结构特征及生物量驱动要素研究

2021年秋季调查了黄渤海沿岸5处人工鱼礁区的浮游生物及相关环境要素,探究了人工鱼礁区浮游生物的群落特征与变化规律,明确了浮游生物的生物量、多样性与人工鱼礁区礁龄和礁体规模的关系。结果发现:共鉴定出浮游植物3门24科64种,浮游动物9大类41种;各人工鱼礁区浮游生物的优势种存在差异,但尖刺伪菱形藻(Pseudo—nitzschia pungens)和强壮箭虫(Sagitta crassa)为各礁区的共有优势种;长礁龄区对浮游生物的养护效果优于短礁龄区,其生物量增加指数(IBI)最大值为7.17,是短礁龄区的10.86~30.47倍;长礁龄区浮游生物群落结构优于短礁龄区,其丰富度指数和多样性指数均值均为短礁龄区的1.1倍。Pearson相关性分析显示,IBI和丰富度指数差值(DMI)与礁龄和礁区规模呈现极显著正相关(P<0.01),其中IBI与礁龄和礁区规模均呈现显著线性函数关系,拟合优度分别为0.91和0.71。结果表明,人工鱼礁建设对浮游生物生物量具有显著提升作用,且生物养护效果受礁区规模和礁龄等礁区特征要素的影响明显。

基于雷达目标特征可分性的一维特征选择方法

海杂波背景下的海上小目标是海洋雷达探测的重难点。针对特征空间内海杂波与小目标特征可分性问题,提出了量化特征之间可分性的度量标准——重叠系数。通过开展对海探测试验获取的2~5级海况实测数据,分别提取时域特征相对平均幅度(Relative Average Amplitude,RAA)、相对峰值峰高(Relative Peak Height,RPH)、时域熵值均值(Time domain Entropy Mean,TEM),频域特征相对多普勒峰高(Relative Doppler Peak Height,RDPH)、相对多普勒向量熵(Relative Vector Entropy,RVE)、频域熵值二阶矩(Second moment of Frequency domain Entropy,SOFE),计算出重叠系数。通过特征检测器进行检测性能对比,低海况下,相对平均幅度、相对峰值峰高、时域熵值均值、相对多普勒峰高、频域熵值二阶矩特征之间重叠系数均在0.3以下,对应特征检测器的检测概率均在85%以上;高海况下其特征之间重叠系数均在0.7以上,对应特征检测器的检测概率均在50%以下。相对多普勒向量熵在4种海况下可分性较小,其对应的特征检测器性能较差。结果验证了重叠系数在一维特征选择的应用可行性,为多特征融合目标检测提供了一定支持。

典型多尺度海面结构体辐射散射方向-光谱特性计算与分析

针对3级以上海况的高精度海洋场景红外仿真问题,提出一种“先拆后建”的研究思路:将含泡沫和破碎波的多尺度海面抽象为粗糙海面、泡沫、破碎波的组合,进而拆解出“粗糙海面”、“含泡沫粗糙海面”、“含破碎波粗糙海面”3类典型多尺度海面结构体,最后通过海面栅格化、结构体匹配、方向-光谱特性重构渲染等方法,由3类典型多尺度结构体方向-光谱特性组合重构大范围海面辐射散射特性,完成多尺度海面“气-面-体”耦合辐射/散射特性的计算。对拆解出的3类典型多尺度海面结构体分别开展多尺度耦合辐射、散射特性建模研究,构建3类多尺度海面结构体辐射散射方向-光谱特性计算模型,并对结构体辐射散射方向-光谱特性的影响因素进行分析,结果表明:随着海面风速的增大,海面典型结构体中的泡沫厚度及气泡浓度逐渐增大,使得结构体的散射能力增强,从而增大结构体的双向反射分布函数;随着探测波长的增大,海水的吸收性显著增强,导致不同风速条件下结构体双向反射分布函数之间的差异显著增大;对于不同的入射角,结构体双向反射分布函数最大值对应的天顶角随入射天顶角的变化逐渐发生变化。

结合渐进式特征金字塔和极化自注意力机制的海雾图像检测

通过对基准模型SegFormer进行两方面的改进优化,开展面向海雾图像检测方法的研究。一方面,引入渐进式特征金字塔融合模块(AFPN),有效融合海雾图像的局部和全局特征,提升模型对不同大小的海雾目标的检测能力。另一方面,引入极化自注意力机制(PSA),有效聚焦图像的细粒度空间信息,捕获海雾的边缘特征,提升模型在云雾混合区域的海雾检测能力。在真实的海雾图像数据集上进行消融实验和对比实验,所提出的模型(简称为AFPSSegFormer),与基准模型相比,mIoU、Precision和m PA指标分别提升了2.38%、2.78%与0.31%,验证了所提出模型在海雾检测方面的有效性。

基于多维特征融合的海面目标检测

为提高海面目标的检测概率,提出一种多维特征融合的目标检测方法。首先,在时域的基础上,提取赫斯特(Hurst)指数和信息熵(IE)2种特征。其次,在频域的基础上,提取频域方差与均值比(FVAR)作为特征。然后,在时频域的基础上,提取短时傅里叶变换(STFT)后的时频图作为特征。最后,使用2支改进的卷积神经网络(CNN)分别训练一维特征和二维特征,之后联合2支网络,得到最终的目标检测结果。进一步与传统卷积神经网络作对比,结果显示在相同训练条件下,所提方法的计算时间缩短40%以上。

利用重力资料研究苏禄海地区断裂构造

为了研究苏禄海地区断裂构造特征,收集并整理了研究区的自由空间重力异常数据,利用滑动平均滤波的方法对自由空间重力异常数据进行处理,得到局部重力异常.结合前人研究成果,对研究区的自由空间重力异常和局部重力异常特征进行深入分析,探讨了研究区断裂构造分布特征.研究结果显示,研究区的重力异常有明显的分区性,大致以潘丹-锡帕莱-第波罗-拉巴松-仙那港为界,分界线南部与北部重力变化相差较大.基于重力异常特征确定了9组不同规模的断裂带,这些断裂带主要呈北东向或北西向展布,延伸距离较长,规模较大,对苏禄海地区的构造单元的划分及部分复杂地质构造的形成起控制作用.

融合多尺度和上下文的无人机救援小目标检测算法

针对无人机(UAV,unmanned aerial vehicle)图像中小目标所包含的特征信息少,导致模型检测精度不足的问题,面向无人机海面救援任务提出了一种融合多尺度和上下文信息的图像小目标检测算法。首先,针对小目标特征信息设计上下文增强模块,通过增强特征层的上下文信息,有效地增加了模型对小目标的处理能力。其次,为提高模型的鲁棒性,设计了空间注意力模块加强对重要特征的学习。最后,使用平衡L1损失函数优化基线算法的损失函数,加强了模型检测时的稳定性。基于Tiny-Person数据集,与基准算法进行大量实验对比,所提算法在AP50_tiny上提高了2.06%,一定程度上提高了对海面小目标的检测性能,对救援行动具有积极影响。

基于相对多普勒峰高特征的OS-CFAR改进方法

在传统有序统计类恒虚警的基础上,提出了1种基于相对多普勒峰高特征的改进有序统计类恒虚警检测方法。该检测算法结合相对多普勒峰高(RDPH)特征和有序统计类(OS-CFAR)检测算法的优势,对雷达回波数据的相对多普勒峰高特征进行计算,通过排序选取参考单元的特征估计,得到检测门限,并通过仿真与实测数据测试对比该算法与其他传统恒虚警算法在不同背景下的检测性能,验证该算法的优势。结果表明:相较于传统均值类、有序统计类恒虚警检测算法,基于相对多普勒峰高特征的改进OS-CFAR检测算法在实测海雷达数据的高海况场景下能够达到更好的检测概率。

利用全极化SAR数据的极化特征获取海冰密集度的算法

本文提出了一种利用全极化SAR数据的极化特征获取海冰密集度算法。首先,对全极化SAR数据进行多视化及滤波等预处理,以获取相干矩阵与协方差矩阵;其次,通过相干矩阵与协方差矩阵获取若干极化特征,对这些极化特征进行相关性与冗余性分析,构建最优特征空间;然后,将最优特征空间作为输入量放入神经网络分类器中,得到海冰分类结果;最后,根据海冰分类结果提取海冰密集度。选用拉布拉多南部海域2景全极化Radarsat-2影像获取海冰密集度,与业务化海冰密集度产品ASI-3125进行对比研究。本文算法结果与ASI-3125海冰密集度分布趋势基本一致,总体上略大于ASI-3125海冰密集度,标准差值分布为3.46%和6.82%,说明利用高分辨率全极化SAR数据在监测边缘区域小尺寸破碎海冰方面具有优势。