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1.
This paper proposes a novel approach to analyze and design the formation keeping control protocols for multiple underwater vehicles in the presence of communication faults and possible uncertainties. First, we formulate the considered vehicle model as the Port-controlled Hamiltonian form, and introduce the spring-damping system based formation control. Next, the dynamics of multiple underwater vehicles under uncertain relative information is reformulated as a network of Lur’e systems. Moreover, the agents under unknown disturbances generated by an external system are considered, where the internal model is applied to tackle the uncertainties, which still can be regulated as the Lur’e systems. In each case, the formation control is derived from solving LMI problems. Finally, a numerical example is introduced to illustrate the effectiveness of the proposed theoretical approach. 相似文献
2.
Kosuke Mori Takeshi Matsuno Tomoharu Senjyu Naoki Hirose In-Seong Han 《Journal of Oceanography》2009,65(3):301-310
Temporal variations in temperature and salinity observed in 2004 were investigated on a short time scale in the Tsushima Strait.
The data were obtained by long-term in situ measurements at Mitsushima and Futaoi Island using an instrument equipped with
a piston-type wiper to avoid biofouling. In addition, the temperature and salinity values of the surface layer obtained by
a commercial ferryboat between Hakata and Busan were used to investigate their spatiotemporal variations. Temperature and
salinity variations with a time scale of several days had a negative correlation in the summer. This evidence suggests that
a warm and less saline water mass, which is considered to be mainly the Changjiang Diluted Water (CDW), flowed intermittently
through the Tsushima Strait in summer. In late July 2004, a large low-salinity water mass was detected in the Tsushima Strait.
At that time, the freshwater transport through the Tsushima Strait transiently reached about 12 × 104 m3s−1, which is estimated from observed acoustic Doppler current profiler (ADCP) data along a ferryboat line and inferred salinity
profiles. This estimated value is more than double the maximum of the climatological monthly mean of the Changjiang discharge.
Furthermore, salinity and surface current data obtained by high frequency ocean radar (HF radar) indicate that water properties
at Mitsushima may occasionally represent part of the water flowing through the western channel via a countercurrent, although
Mitsushima is geographically located in the eastern channel. 相似文献
3.
三疣梭子蟹(Portunus trituberculatus)低盐耐受性和体重的遗传参数估计及其相关分析 总被引：1，自引：0，他引：1
为评估三疣梭子蟹(Portunus trituberculatus)体重及其低盐耐受性遗传力,本实验构建了20个三疣梭子蟹全同胞家系,分别在其60、90养殖日龄测量其各个家系的体重,并在60日龄时取每个家系90个个体,在盐度4胁迫下分别在12h、24h、48h、72h统计其死亡率,作为衡量其盐度耐受性指标。利用全同胞方差组分分析法评估其低盐耐受性及体重遗传参数。结果发现三疣梭子蟹在60日龄下,其体重遗传力为0.45,其在12h、24h、48h、72h处理条件低盐耐受性遗传力分别为0.13、0.18、0.21、0.29。通过聚类分析的方法将其耐受性状分为3类,并通过相关性分析发现三疣梭子蟹生长性状与低盐耐受性性状的相关系数为0.143,检验并不显著(P=0.547),说明三疣梭子蟹生长性状与耐低盐性状并不相关,在选育时可采用复合选育,提高育种效率。 相似文献
4.
坛紫菜耐低盐品系的选育与特性分析 总被引：5，自引：1，他引：4
本实验室采用人工诱变技术获得一个坛紫菜耐低盐品系(YZ-7),为了验证该品系的耐低盐性状能否遗传,本文对其壳孢子和F1叶状体的低盐耐受性分别进行了测试,并以坛紫菜野生品系(WT)作为对照,结果表明:在不同盐度下培养2周的YZ-7和WT的壳孢子,在26盐度组存活率无显著差异;在15盐度组,YZ-7的壳孢子存活率和假根发生率分别比WT提高了34%和35%;在8和5盐度组,YZ-7的壳孢子存活率、分裂率及假根发生率分别比WT提高了65%、32%和62%,以及137%、80%和154%;在3盐度组,YZ-7的壳孢子存活率和分裂率分别比WT提高了458%和171%,其中约44.9%的YZ-7壳孢子萌发体能形成假根,而WT的壳孢子萌发体基本上不长假根。在26盐度中培养35d后的F1叶状体再分别在26、15、8、5和3盐度下培养30d,YZ-7叶状体的特定生长率分别为WT的1.7、1.9、1.5、1.6和1.6倍,绝对生长率分别是WT的3.4、4.1、1.8、2.0和1.6倍。此外,YZ-7叶状体的叶绿素荧光活性(PSⅡ最大光量子产量、实际光量子产量)及三种主要光合色素(叶绿素a、藻红蛋白和藻蓝蛋白)的含量也明显高于WT。上述结果证实,坛紫菜选育品系YZ-7是一个耐低盐且生长快的优良品系,其优良性状可稳定传递给下一代,有望被培育成适宜栽培的新品种。 相似文献
5.
太阳能、风能和潮汐能等可再生能源的发电系统,具有间歇性发电的特性.因此,具有快速响应、发电效率高的燃气轮机发电系统,能够在可再生能源发电间歇出现时充当替代系统,不仅稳固电网的负荷能力,还有助于推动可再生能源的发展.由于燃气轮机是一个模型包含未知的复杂非线性系统,目前针对转速环节主要采取传统PID控制技术.然而,实际运行中系统工况发生变化时,控制器参数不能随着这些变化做出相应的调整,使得控制效果欠佳,执行器故障的出现也可能导致系统无法正常工作.因而,本文针对单轴燃气轮机的孤岛发电模式,结合燃气轮机系统特性,基于反步法的设计思路,引入不依赖于系统模型的鲁棒自适应控制策略,并加入容错控制和Nussbaum函数构造转速控制器.在控制器设计过程中融合动态面方法,解决高阶系统中反步法引起的计算爆炸问题.最后,通过仿真,验证了控制器的可靠性. 相似文献
6.
Abstract Common native fish species that are rare in New Zealand rivers with high suspended solids (SS) concentrations were identified to determine which species were likely to be most affected by high SS concentrations. Mortality rates for the three most sensitive species (banded kokopu Galaxias fasciatus, redfin bully Gobiomorphus huttoni, common smelt Retropinna retropinnd) were measured over a range of SS concentrations to identify lethal concentrations. The survival of banded kokopu and redfin bully was not reduced by SS concentrations up to 43 000 g m?3; however, the 24‐h survival of common smelt was reduced by SS concentrations over 1000 g m?3, and its median lethal concentration (LC50) was close to 3000 g m?3. SS concentrations over 3000 g m?3 for more than 24 h will therefore reduce smelt but not affect the mortality of most other common native fish species. Although mortality from high concentrations of SS can account for the scarcity of smelt in rivers with high SS concentrations, mortality from high SS does not explain the scarcity of banded kokopu or redfin bully in such rivers. High turbidity (>20 nephelometric turbidity units) is known to limit the upstream migration and recruitment of juvenile banded kokopu in rivers with increased SS concentrations. Banded kokopu is therefore affected by increased turbidity from SS rather than lethal SS concentrations. As redfin bully were not affected by either high turbidity levels or high SS concentrations, the low abundance of this species in rivers with high SS concentrations is likely to be related to the siltation of benthic habitats. 相似文献
7.
采用人工控温的方式, 对构建的31个F1红鳍东方鲀(Takifugu rubripes)全同胞家系开展低温胁迫实验, 获得耐低温性状低温累计存活时间(CDH), 基于混合线性模型分别开展耐低温性状和生长性状遗传参数评估,对每一性状是否需要考虑共同环境效应所构建的两种模型进行似然比检验。结果显示, 经似然比检验, 最终选用模型A和模型BF进行耐低温和生长性状遗传评估; 耐低温性状CDH遗传力为(0.27±0.08),属于中等遗传力; 体重BW遗传力为(0.36±0.13), 属于中等遗传力, 体长BL遗传力为(0.14±0.06), 属于低等遗传力, 经检验, 遗传力估计值均达到极显著水平(P<0.01)。CDH和体重、体长的遗传相关分别为(-0.40±0.22)和(-0.44±0.24), 表型相关分别为(-0.09±0.06)和(-0.16± 0.05), 均为负相关; 体重和体长之间的遗传相关为(0.92±0.05), 表型相关为(0.80±0.02), 呈正相关且结果极显著(P<0.01)。研究结果表明, 红鳍东方鲀的耐低温性状和生长性状都具有较好的改良潜力, 考虑到两性状间存在负遗传相关, 在开展耐低温选育时, 对首先不同性状进行品系选育, 然后利用品系间杂交培育出耐高温、生长快的新品种。该项研究首次完成了红鳍东方鲀耐低温性状的遗传参数评估, 为制订红鳍东方鲀耐低温选育育种规划提供了理论依据。 相似文献
8.
针对考虑传感器故障的柔性航天器姿态系统,提出了一种主动容错控制方法.首先,通过对测量输出进行滤波,将传感器故障转化为执行器故障形式;接着,设计一个基于未知输入观测器的自适应故障估计观测器,对未知故障进行辨识,同时,采用了一个故障检测观测器,对故障的发生进行检测;然后,利用故障估计信号对系统输出进行调节,结合自适应积分滑模和线性矩阵不等式技术设计输出反馈容错控制器;最后,对所设计的主动容错控制方法进行仿真,验证了所提方法的有效性. 相似文献
9.
Ramesh Dhungel Robert Aiken Paul D. Colaizzi Xiaomao Lin Dan O'Brien R. Louis Baumhardt David K. Brauer Gary W. Marek 《水文研究》2019,33(15):2110-2130
The backward‐averaged iterative two‐source surface temperature and energy balance solution (BAITSSS) model was developed to calculate evapotranspiration (ET) at point to regional scales. The BAITSSS model is driven by micrometeorological data and vegetation indices and simulates the water and energy balance of the soil and canopy sources separately, using the Jarvis model to calculate canopy resistance. The BAITSSS model has undergone limited testing in Idaho, United States. We conducted a blind test of the BAITSSS model without prior calibration for ET against weighing lysimeter measurements, net radiation, and surface temperature of drought‐tolerant corn (Zea mays L. cv. PIO 1151) in a semiarid, advective climate (Bushland, Texas, United States) in 2016. Later in the season (20 days), BAITSSS consistently overestimated ET by up to 3 mm d?1. For the entire growing season (127 days), simulated versus measured ET resulted in a 7% error in cumulative ET, RMSE = 0.13 mm h?1, and 1.70 mm d?1; r2 = 0.66 (daily) and r2 = 0.84 (hourly); MAE = 0.08 mm h?1 and 1.24 mm d?1; and MBE = 0.02 mm h?1 and 0.58 mm d?1. The results were comparable with thermally driven instantaneous ET models that required some calibration. Next, the initial soil water boundary condition was reduced, and model revisions were made to resistance terms related to incomplete cover and assumption of canopy senescence. The revisions reduced discrepancies between measured and modelled ET resulting in <1% error in cumulative ET, RMSE = 0.1 mm h?1, and 1.09 mm d?1; r2 = 0.86 (daily) and r2 = 0.90 (hourly); MAE = 0.06 mm h?1 and 0.79 mm d?1; and MBE = 0.0 mm h?1 and 0.17 mm d?1 and generally mitigated the previous overestimation. The advancement in ET modelling with BAITSSS assists to minimize uncertainties in crop ET modelling in a time series. 相似文献
10.
利用LEVITUS温盐资料、HOAPS降水及蒸发资料以及OFES模式资料等分析加里曼丹岛西北侧表层低盐水的季节变化规律,并使用盐度平衡模式诊断了海面淡水通量、径流、卷挟作用以及平流作用对低盐水变化的贡献.分析表明:加里曼丹西北侧全年均存在1个低盐水团,其季节变化具有"双峰"特征,3月至4月以及10月至11月会发生2次低... 相似文献