Prediction of mesophotic coral distributions in the Au‘au Channel, Hawaii

The primary objective of this study was to predict the distribution of mesophotic hard corals in the Au‘au Channel in the Main Hawaiian Islands (MHI). Mesophotic hard corals are light-dependent corals adapted to the low light conditions at approximately 30 to 150 m in depth. Several physical factors potentially influence their spatial distribution, including aragonite saturation, alkalinity, pH, currents, water temperature, hard substrate availability and the availability of light at depth. Mesophotic corals and mesophotic coral ecosystems (MCEs) have increasingly been the subject of scientific study because they are being threatened by a growing number of anthropogenic stressors. They are the focus of this spatial modeling effort because the Hawaiian Islands Humpback Whale National Marine Sanctuary (HIHWNMS) is exploring the expansion of its scope—beyond the protection of the North Pacific Humpback Whale (Megaptera novaeangliae)—to include the conservation and management of these ecosystem components. The present study helps to address this need by examining the distribution of mesophotic corals in the Au‘au Channel region. This area is located between the islands of Maui, Lanai, Molokai and Kahoolawe, and includes parts of the Kealaikahiki, Alalākeiki and Kalohi Channels. It is unique, not only in terms of its geology, but also in terms of its physical oceanography and local weather patterns. Several physical conditions make it an ideal place for mesophotic hard corals, including consistently good water quality and clarity because it is flushed by tidal currents semi-diurnally; it has low amounts of rainfall and sediment run-off from the nearby land; and it is largely protected from seasonally strong wind and wave energy. Combined, these oceanographic and weather conditions create patches of comparatively warm, calm, clear waters that remain relatively stable through time. Freely available Maximum Entropy modeling software (MaxEnt 3.3.3e) was used to create four separate maps of predicted habitat suitability for: (1) all mesophotic hard corals combined, (2) Leptoseris, (3) Montipora and (4) Porites genera. MaxEnt works by analyzing the distribution of environmental variables where species are present, so it can find other areas that meet all of the same environmental constraints. Several steps (Figure 0.1) were required to produce and validate four ensemble predictive models (i.e., models with 10 replicates each). Approximately 2,000 georeferenced records containing information about mesophotic coral occurrence and 34 environmental predictors describing the seafloor’s depth, vertical structure, available light, surface temperature, currents and distance from shoreline at three spatial scales were used to train MaxEnt. Fifty percent of the 1,989 records were randomly chosen and set aside to assess each model replicate’s performance using Receiver Operating Characteristic (ROC), Area Under the Curve (AUC) values. An additional 1,646 records were also randomly chosen and set aside to independently assess the predictive accuracy of the four ensemble models. Suitability thresholds for these models (denoting where corals were predicted to be present/absent) were chosen by finding where the maximum number of correctly predicted presence and absence records intersected on each ROC curve. Permutation importance and jackknife analysis were used to quantify the contribution of each environmental variable to the four ensemble models.

Generating power from waves on a breakwater.

Outlines the possibility for wave power generation at artificial islands by construction of a breakwater. Reviews the development of wave energy systems, and describes several wave generators, e.g. the Mauritius lagoon system, the Nodding Duck, the oscillating cylinder, the oscillating water column and the Lancaster Bag. Applications and costs are outlined. (C.J.U.)

Design of a pitching and surging point absorber.

The linear dynamics, operation, and engineering aspects of P.S. FROG, a point absorber wave energy conversion buoy, are summarized. The device consists of a floating flap or paddle facing the waves and reacting against them through an interior moving mass in an enlarged section at the bottom of the buoy.

Electronic states of InAs/GaAs tyre-shape quantum ring

In the framework of the effective mass theory, this paper calculates the electron energy levels of an InAs/GaAs tyre-shape quantum ring (TSQR) by using the plane wave basis. The results show that the electron energy levels are sensitively dependent on the TSQR's section thickness d, and insensitively dependent on TSQR's section inner radius R-1 and TSQR's inner radius R-2. The model and results provide useful information for the design and fabrication of InAs/GaAs TSQRs.

中国海洋能专利研究

专利是除论文外的又一非常重要的科技成果。目前专利申请工作并未得到足够重视，并且文献中对专利技术成果的反映甚少。文章对中国国家知识产权局（SIPO）专利数据库中海洋能专利授权情况进行了分类统计。介绍了波浪能、潮汐能、温差能的最新专利，并指出了该领域专利申请的热点和空白领域。最后根据统计数据从专利的角度分析了中国海洋能研究的进展和前景。

The effects of random surface waves on the steady Ekman current solutions

The response of near-surface current profiles to wind and random surface waves are studied based on the approach of Jenkins [1989. The use of a wave prediction model for driving a near surface current model. Dtsch. Hydrogr. Z. 42,134-149] and Tang et al. [2007. Observation and modeling of surface currents on the Grand Banks: a study of the wave effects on surface currents. J. Geophys. Res. 112, C10025, doi:10.1029/2006JC004028]. Analytic steady solutions are presented for wave-modified Ekman equations resulting from Stokes drift, wind input and wave dissipation for a depth-independent constant eddy viscosity coefficient and one that varies linearly with depth. The parameters involved in the solutions can be determined by the two-dimensional wavenumber spectrum of ocean waves, wind speed, the Coriolis parameter and the densities of air and water, and the solutions reduce to those of Lewis and Belcher [2004. Time-dependent, coupled, Ekman boundary layer solutions incorporating Stokes drift. Dyn. Atmos. Oceans. 37, 313-351] when only the effects of Stokes drift are included. As illustrative examples, for a fully developed wind-generated sea with different wind speeds, wave-modified current profiles are calculated and compared with the classical Ekman theory and Lewis and Belcher's [2004. Time-dependent, coupled, Ekman boundary layer solutions incorporating Stokes drift. Dyn. Atmos. Oceans 37, 313-351] modification by using the Donelan and Pierson [1987. Radar scattering and equilibrium ranges in wind-generated waves with application to scatterometry. J. Geophys. Res. 92, 4971-5029] wavenumber spectrum, the WAM wave model formulation for wind input energy to waves, and wave energy dissipation converted to currents. Illustrative examples for a fully developed sea and the comparisons between observations and the theoretical predictions demonstrate that the effects of the random surface waves on the classical Ekman current are important, as they change qualitatively the nature of the Ekman layer. But the effects of the wind input and wave dissipation on surface current are small, relative to the impact of the Stokes drift. (C) 2008 Elsevier Ltd. All rights reserved.

基于多种群遗传算法的波能装置的优化设计及分析

作为可再生能源,波浪能的吸收和利用一直是国内外热点研究内容之一。本文提出一种新的基于惯性摆结构的波浪能吸收转换方法,对这种结构在波浪力作用下的频域响应进行了分析,建立了其最优化能量获取模型,提出采用多种群遗传算法对其结构进行优化设计,并针对系统所受波浪力(矩)随载体半径改变而改变,且求取困难的问题,采用最小二乘法对波浪力(矩)与载体半径变化的关系进行了拟和。通过优化结果找出影响结构获取波浪能量的因素,仿真结果表明了方法的先进性,为进一步的应用研究和频域波能获取研究奠定了基础。

基于惯性摆的波能系统研究

提出了一种基于惯性摆结构的波浪能吸收转换方法,并对采用此结构构成的水中载体所受到的波浪力及水动力进行了理论分析,建立了实验模型,对其进行了运动学、动力学仿真实验,仿真结果证明了方案的可行性。

基于惯性摆的波浪能获取机理与方法研究

随着陆地战略资源日益短缺以及经济的全球化进展，海洋资源的开发利用已成为沿海各国的重要发展战略之一，也成为地球资源保护与开发的关注热点。 海洋资源开发和利用能力对于一个国家的科研、经济实力具有重大的影响及意义。由于海洋资源开发利用和地球环境监测的迫切需求，促进了水下机器人、水下潜器等无人水中移动载体技术的发展。能源供给技术是水中移动载体系统的关键技术，能源技术对海洋人工系统的生存、作业、自主能力提升具有重要意义。目前海洋移动人工系统主要依赖自携带能源形式，针对水中移动载体的能量自补给技术研究还处于探索阶段。 地球表面有70%的面积被海水所覆盖，海水中蕴藏巨大的波浪能。具有环保、再生特色的波浪能开发利用技术长期以来一直受到国内外科研人员的关注。随着海洋战略地位的提升，海洋自主人工系统已成为海洋科学技术的重点发展内容。利用波浪能为海洋人工移动载体进行能量补给，是对于海洋波浪能利用的一种新的方法和思路。这对于提高海洋人工系统的自主生存、续航能力，提高人类在海洋资源与环境的探测、开发利用等方面的技术能力无疑具有重大意义。因而研究面向海洋人工系统的波浪能利用机理和系统实现技术无疑具有广泛的应用前景。 本文针对海洋人工移动载体自主能量获取利用这一重大科学技术需求，依托中国科学院基地创新基金项目“基于惯性摆原理的无源系统研究”，探索基于惯性摆机理的移动载体波浪能自主获取的机理，研究相关设计理论和技术方法。 由于目前尚无基于惯性摆机理的海洋移动载体能量自补给技术的相关研究成果。因而本论文的研究主要从理论分析和实验方法两个方面开展。重点分析了惯性摆的外激励能量获取机理，基于惯性摆的波浪机械能获取理论的可行性；开展了惯性摆载体的水动力学建模，原理样机的仿真，频域下的能量建模和优化，非线性波浪条件模拟，惯性摆载体的能量获取结构优化等研究工作。主要研究工作如下： 1.针对基于惯性摆机理的移动载体随机波能获取研究方案，分析了相关单摆及惯性摆机械能量转换机理，采用动量及动量矩定理，构建了惯性摆载体的六自由度运动学和动力学方程。 2．进行了相关水动力系数获取方法研究，获得了水动力系数数学描述。同时，采用虚拟样机方法进行惯性摆载体能量获取的研究，证明了基于惯性摆的波能自主获取方法的可行性及有效性。 3.针对虚拟样机方法建模的复杂性及容易产生错误等问题，进行了基于BP神经网络方法的惯性摆能量吸收效率的建模研究。并研究了基于该模型的不同波向角及波浪频率、载体外形尺寸、质量等的虚拟样机的波浪能吸收效率问题，为载体机构的改进及设计提供了较好的理论模型和基础。 4.开展了频域下惯性摆能量吸收效率研究。研究了基于频域的单惯性摆载体的动力学建模方法以及载体结构优化方法，提出采用多种群遗传算法进行载体结构的优化设计方法。通过仿真实验证明了相关算法的有效性，为系统的优化设计研究提供了理论基础。 5.以能量吸收效率最大为目标，进行了多种惯性摆形式的能量获取最大化分析研究，提出了包括单摆在内的多种可行的形式，给出了对比研究结果，可根据不同的提取形式而确定采用的惯性摆的形式。 6.采用PM谱对非线性波浪进行了模拟，研究了单惯性摆结构在非线性波浪力下的能量获取情况，仿真结果表明，在非线性条件下获取的惯性摆能量要更多，而其他波向角、频率等优化条件均与线性条件下的研究结果相同。

Boosting Blue Growth in a Mild Sea: Analysis of the Synergies Produced by a Multi-Purpose Offshore Installation in the Northern Adriatic, Italy

In the near future, the oceans will be subjected to a massive development of marine infrastructures, including offshore wind, tidal and wave energy farms and constructions for marine aquaculture. The development of these facilities will unavoidably exert environmental pressures on marine ecosystems. It is therefore crucial that the economic costs, the use of marine space and the environmental impacts of these activities remain within acceptable limits. Moreover, the installation of arrays of wave energy devices is still far from being economically feasible due to many combined aspects, such as immature technologies for energy conversion, local energy storage and moorings. Therefore, multi-purpose solutions combining renewable energy from the sea (wind, wave, tide), aquaculture and transportation facilities can be considered as a challenging, yet advantageous, way to boost blue growth. This would be due to the sharing of the costs of installation and using the produced energy locally to feed the different functionalities and optimizing marine spatial planning. This paper focuses on the synergies that may be produced by a multi-purpose offshore installation in a relatively calm sea, i.e., the Northern Adriatic Sea, Italy, and specifically offshore Venice. It analyzes the combination of aquaculture, energy production from wind and waves, and energy storage or transfer. Alternative solutions are evaluated based on specific criteria, including the maturity of the technology, the environmental impact, the induced risks and the costs. Based on expert judgment, the alternatives are ranked and a preliminary layout of the selected multi-purpose installation for the case study is proposed, to further allow the exploitation of the synergies among different functionalities.

Local Conentration of Waves due to Abrupt Alongshore Variation of Nearshore Bathymetry

Small-scale physical and numerical experiments were conducted to investigate the local concentration of waves (monochromatic and group) due to abrupt change of nearshore bathymetry in alongshore direction. Wave run-up motions along the shoreline were measured using an image analysis technique to compare localized concentration of wave energy, when waves propagate a over bathymetry composing rhythmic patterns of mild/steep slope bottom configurations. Measured alongshore variation of maximum wave run-up heights showed significant peak near the boundary, which has sudden alongshore change of depth, both under monochromatic and group wave trains. This phenomenon is found to be due to interaction of waves with neashore currents, which is further enhanced by excitation of long wave components by breaking of group waves. Furthermore, this paper discusses results of preliminary experiments carried out to test the effectiveness of several shore protection structure layouts in mitigating such wave concentrations. Numerical simulations were performed by using a model developed based on Nwogu (1993) Boussinesq-type equations; coupled with a transport equation to model energy dissipation due to wave breaking.

Observations of ubiquitous compressive waves in the Sun's chromosphere

The details of the mechanism(s) responsible for the observed heating and dynamics of the solar atmosphere still remain a mystery. Magnetohydrodynamic waves are thought to have a vital role in this process. Although it has been shown that incompressible waves are ubiquitous in off-limb solar atmospheric observations, their energy cannot be readily dissipated. Here we provide, for the first time, on-disk observation and identification of concurrent magnetohydrodynamic wave modes, both compressible and incompressible, in the solar chromosphere. The observed ubiquity and estimated energy flux associated with the detected magnetohydrodynamic waves suggest the chromosphere is a vast reservoir of wave energy with the potential to meet chromospheric and coronal heating requirements. We are also able to propose an upper bound on the flux of the observed wave energy that is able to reach the corona based on observational constraints, which has important implications for the suggested mechanism(s) for quiescent coronal heating. © 2012 Macmillan Publishers Limited. All rights reserved.