Duffing方程的遥远概周期解

本文通过指数二分性和上下解方法,在比较自然的条件下,证明了二阶非线性常微分方程u″+cu′+g(u)=p(t)的遥远概周期解的存在性,其中g∈C¹(R),而p是遥远概周期函数。     

一类广义Sine-Gordon方程的概周期解

用最大值原理和Banach压缩映像原理研究一类广义Sine-Gordon方程的概周期解问题,证明概周期解的存在‖u‖L∞<π2中的唯一性。     

具竞争扩散Lotka-Volterra系统概周期解研究

讨论一类推广的具竞争扩散Lotka—Volterra系统，利用微分不等式，证明了该系统概周期解的存在唯一性及其在壳扰动下的稳定性；推广和改进了秦发金、罗桂烈等在Lotka—Volterra系统概周期解的结果。     

二阶时滞微分方程的Besicovitch概周期解

研究二阶时滞微分方程的Besicovitch概周期解的存在性和唯一性,进而讨论Lipschitz非线性的情况。     

时滞Hopfield神经网络的概周期解

主要研究一类无限区间上的具有S-分布时滞的Hopfield神经网络模型的概周期解问题。一方面去掉激活函数必须满足全局Lipschitz条件的限制,另一方面扩大时滞的应用范围,利用Banach不动点定理和不等式分析技巧,得到了保证所研究的神经网络的概周期解的存在性与全局吸引性的充分条件,并用一个例子说明了所得结果的有效性与可行性。本文结果在一定程度上改善和推广了已有文献的结论。     

Duffing振子系统周期解的唯一性与精确周期信号的获取方法

研究Duffing振子系统的周期解的唯一性与精确周期信号的获取方法. 应用定性分析方法,获得了一类Duffing振子系统具有唯一周期解的必要条件,同时也得到了一类更广泛的非线性周期系统的周期解的唯一性.在一定条件下,给出了Duffing振子系统精确周期信号的获取方法.     

一个单种P-Z赤潮生态模型的非线性分析

对植食性浮游动物摄食模型(仅对一个赤潮藻类)进行非线性分析,得出了该确定性参数方程的稳定性条件和发生 Hopf 分岔的条件,并且用数值模拟证实了理论分析.为更好的吻合实际情况,提出了含有变参数的赤潮藻类生长模型.模型中用一个周期函数来近似模拟了藻类生长率参数,并对此模型做了数值模拟.结果表明,引入变参数后的模型能出现概周期解,更能体现藻类生长的季节性特点,与实际情况符合更好.     

一类含脉冲的随机区间细胞神经网络模型的周期解和稳定性

讨论了一类含脉冲的S-分布时滞随机区间细胞神经网络的周期解和指数稳定性问题。利用随机分析的知识、不等式技巧和Poincaré压缩映像理论,研究了系统周期解的存在性和稳定性,得到了S-分布时滞随机细胞神经网络周期解的存在性和全局p阶指数稳定性的新代数判据,同时对周期解的指数收敛率进行了估计,最后通过例子说明了结果的实用性和有效性。     

时间周期Hamilton-Jacobi方程渐近解的表达式

本文研究时间周期Hamilton-Jacobi方程的长时间渐近解。通过给出时间周期情形下的Aubry集的定义,得到2个周期渐近解的表达式。     

S分布时滞静态递归神经网络周期解的存在与全局指数稳定性

利用迭合度理论和推广的Halanay矩阵时滞微分不等式讨论了S-分布时滞静态递归神经网络模型的周期解,给出了周期解存在性和全局指数稳定性的充分条件。     

Designing a Dependable and Fault-Tolerant Semiautonomous Distributed Control Data Collection Network With Opportunistic Hierarchy

This paper presents the satellite-linked data acquisition and photogrammetry (SLiDAP) network, designed to conduct shore-based, close-range 3-D imaging in remote areas. The lack of communications and power infrastructure and ability to service the system requires periodic, synchronous operations of multiple semiautonomous elements with a high degree of reliability. The SLiDAP system uses an opportunistic network architecture based on four distinct levels of control, to accommodate unpredictable operational constraints and failures. The synchronization of periodic tasks in a distributed control and remotely operable network are highlighted, and measures to increase the reliability of system operations are discussed, including hardware redundancy, intelligent watchdog timer, software error tolerance, self-repair, and remote update capability. The characteristics of the SLiDAP system within the concept of autonomic computing are discussed.     

First encounter with a live male blanket octopus: The world's most sexually size‐dimorphic large animal

The first encounter with a live male blanket octopus, Tremoctopus violaceus Chiaie, 1830, illustrates the most extreme example of sexual size‐dimorphism in a non‐microscopic animal. Females attain sizes of up to 2 m long—almost 2 orders of magnitude larger than the 2.4‐cm‐long male. Weight ratios between the sexes are at least 10 000:1 and are likely to reach 40 000:1. Sexual selection and the unique defensive strategy of carrying cnidarian stinging tentacles may both have contributed to the evolution of this extreme size‐dimorphism. Such dimorphism is not seen in any other animal remotely as large.     

An ROV Stereovision System for Ship-Hull Inspection

Ship hulls, as well as bridges, port dock pilings, dams, and various underwater structures need to be inspected for periodic maintenance. Additionally, there is a critical need to provide protection against sabotage activities, and to establish effective countermeasures against illegal smuggling activities. Unmanned underwater vehicles are suitable platforms for the development of automated inspection systems, but require integration with appropriate sensor technologies. This paper describes a vision system for automated ship-hull inspection, based on computing the necessary information for positioning, navigation, and mapping of the hull from stereo images. Binocular cues are critical in resolving a number of complex visual artifacts that hamper monocular vision in shallow-water conditions. Furthermore, they simplify the estimation of vehicle pose and motion, which is fundamental for successful automatic operation. The system has been implemented on a commercial remotely operated vehicle (ROV), and tested in pool and dock tests. Results from various trials are presented to demonstrate the system capabilities     

Calculation of adapted black sea fields on the basis of assimilation of climatic temperature and salinity data into the model

A scheme of a periodic assimilation of climatic temperature and salinity data into a model is proposed. In accordance with the criteria chosen on the basis of numerical experiments, an optimum assimilation period of three hours is set. The proposed method allows a hydrodynamic adaptation of the fields of temperature, salinity, and flow velocity that are close to the climatic ones within the framework of the proposed criteria. The main feature of the adapted fields of vertical flows in the layer 0–700 m is their smooth character and an almost complete absence of small-scale noise. The extreme values of vertical velocity in this layer decrease by almost an order of magnitude as compared to analogous values calculated for the variant of data assimilation with a weak adjustment of fields.     

Remote sensing of ocean sound speed profiles by a perceptron neuralnetwork

A method is developed to estimate ocean sound speed profiles through synthesis of remotely measured environmental data and historical statistics of sound speed obtained at a remotely sensed location. Sound speed profiles are represented by an expansion of empirical orthogonal functions (EOF) of the historical sound speed variation, while the remotely sensed environmental data provide real-time information to determine the expansion coefficients. Environmental inputs are limited to sea surface temperature available from satellite infrared sensors, acoustic time-of-flight and ocean bottom temperature measurable from bottom mounted acoustic and thermal transducers. A multilayer perceptron neural network is implemented to learn the functional transformation from the measured environmental input to the desired EOF coefficient output on a set of representative sound speed profiles. Sea surface temperature, time-of-year, and time-of-flight from the acoustic multipath that maximally samples the vertical sound speed are found to be the dominant inputs. The trained network is computationally efficient and produces estimates for untrained environmental inputs with a mean error of 1.1-4.4 m/s     

Stem waves along vertical wall due to random wave incidence

This study investigates stem waves, propagating along a vertical wall, due to obliquely incident random waves through laboratory experiments and numerical simulations. Attention is paid to the difference or similarity between the stem waves due to periodic waves and random waves, the nonlinear and linear characteristics, and the effect of wave breaking on the evolution of stem waves. The following were found from this study: as the incident angle of waves become large or the nonlinearity of the incident waves become small, the significant stem wave height, normalized by the incident significant wave height, becomes large. This tendency is the same as that generated by the Stokes waves or cnoidal waves. However, regardless of the nonlinearity of incident waves, the width of stem waves is almost the same. This is a different point between the stem waves due to periodic and random waves. The wave breaking suppresses the growth of the stem waves.     

Defining the seaward extent of New Zealand's coastal zone

The seaward extent of New Zealand's coastal zone (defined here in a biophysical sense as the area of terrigenous influence) was determined from remotely sensed ocean colour and turbidity data. The cross-shore behavior of the colour and turbidity fields were quantified at a number of transects around the coastline and the locations where these fields changed from coastal to oceanic signatures were identified. Results from these analyses suggest that the coastal zone can extend several hundreds of kilometers offshore. Furthermore, the seaward extent determined from these analyses was not correlated to the underlying bathymetry of the continental shelf and slope; features commonly used to define the offshore extent of coastal zones. The estimated seaward limits determined from the analyses of the remotely sensed data were compared to limited available in situ data and predictions from a numerical circulation model. Observations of coastal zooplankton species several hundreds of kilometers offshore suggest good agreement with the predicted seaward extent of coastal zones determined from the remotely sensed data. Offshore transport of surface particles predicted by the circulation model also suggested that pelagic organisms and suspended inorganic particles may be advected offshore at least several hundreds of kilometers.     

渤海湾海水光谱特性的数值分析——复相关分析

一、序言 从遙感信息中提取海洋信息是海洋遙感应用的核心问题。 从遙感数据提取海洋数据,现在已经有很多方法与模型。各种方法都有它们的长处和短处。从目前发表的遙感文章来看,大多还是使用数理统计模型。它的优点是方法比较简单,且比较精确。缺点是有很大的局限性,它的结果只有在特定的海区、特定的大气条件和飞行