A comparative study of energy performance of hydrostatic seafloor sediment samplers and a new high-efficiency sampler     

《Applied Ocean Research》2019

The hydrostatic energy of high-pressure seawater is a renewable and green energy source for ocean exploration and have been used to replace underwater electrical energy transmission through the cable and underwater battery pack to power seafloor equipment. The advantage of the energy supply method is the cost-effective and the robustness. In the paper, the energy performance of the existing hydrostatic seafloor sediment samplers powered by seawater hydrostatic energy are modelled and analyzed and compared. In view of the common shortcoming of existing technology, a novel hydrostatic seafloor sediment sampler is proposed. The model of energy conversion of the new sampler is built, and its energy performance is obtained. The analysis results indicate that the energy conversion efficiency of the novel sediment sampler is much higher than the existing ones, which means that the new sampler can collect much longer sample with the limited amount of hydrostatic energy. The seawater hydrostatic energy conversion system of the new sampler can also be used to power other seafloor equipment.  相似文献   

Turbulence Diffusion and Energy Spectrum Analysis of Large-scale Current Sheets in Flares     

《Chinese Astronomy and Astrophysics》2021,45(4):470-493

Magnetic reconnection (MR) is one of the most important physical processes for many dynamical phenomena in the universe. Magnetohydrodynamical (MHD) simulation is an effective way to study the MR process and the physical pictures related to the MR. With different parameter setups, we investigate the influences of the Magnetic Reynolds number and spatial resolution on the reconnection rate, numerical dissipation, and energy spectrum distribution in the MHD simulation. We have found that the magnetic Reynolds number $R_m$ has definite impact on the reconnection rate and energy spectrum distribution. The characteristic time for entering into the non-linear phase will be earlier as the Reynolds number increases. When it comes to the tearing phase, the reconnection rate will increase rapidly. On the other hand, the magnetic Reynolds number affects significantly the Kolmogorov microscopic scale $l_{\mathit{ko}}$, which becomes smaller as $R_m$ increases. An extra dissipation is defined as the combined effect of the numerical diffusion and turbulence dissipation. It is shown that the extra dissipation is dominated by the numerical diffusion before the tearing mode instability takes place. After the instability develops, the extra dissipation rises vastly, which indicates that turbulence caused by the instability can enhance the diffusion obviously. Furthermore, the energy spectrum analysis indicates that $l_{\mathit{ko}}$ of the large-scale current sheet may appear at a macroscopic MHD scale very possibly.  相似文献   

海岸波浪多次破碎波能耗散模型   总被引：1，自引：0，他引：1  

闫圣  邹志利 《海洋学报》2020,42(9):30-37

在坡度很缓(接近或小于1∶100)的海岸，波浪在向海岸传播的过程中，可能经历多次破碎，而在两次波浪破碎之间将伴随着波浪恢复(波浪恢复到不破碎状态)。在现有海岸波高计算模型中，波浪破碎是通过波能耗散来模拟的，但所采用的波能耗散模型都不能自动考虑波浪出现多次破碎的过程，特别精确模拟这一过程中出现的波浪恢复。本文提出了解决这一问题的新的波能耗散模型，模型的建立是通过在Dally模型中重新建立稳定波能、饱和波高水深比和波能耗散系数，并引入了波浪恢复的判断条件实现的。该模型的波能耗散在波浪恢复区的值很小故能描述波浪恢复区的波浪运动。与实验结果的对比表明，新模型可以适合缓坡情况波浪多次破碎的波高模拟，而且对不同坡度的平坡和沙坝海岸(1∶100～1∶10)的破碎波模拟都可以给出与实验结果符合的结果，并且可以自动识别多次波浪破碎的存在和波浪恢复的发生。  相似文献   

北极薄冰-煎饼冰区域中不同重力波驱动形成海流的敏感性分析     

张雪妍  戴海瑨  赵军  殷何卿 《海洋学报(英文版)》2020,39(3):123-129

A coupled ocean-ice-wave model is used to study ice-edge jet and eddy genesis during surface gravity wave dissipation in a frazil-pancake ice zone. With observational data from the Beaufort Sea, possible wave dissipation processes are evaluated using sensitivity experiments. As wave energy dissipated, energy was transferred into ice floe through radiation stress. Later, energy was in turn transferred into current through ocean-ice interfacial stress. Since most of the wave energy is dissipated at the ice edge, ice-edge jets, which contained strong horizontal shear, appeared both in the ice zone and the ocean. Meanwhile, the wave propagation direction determines the velocity partition in the along-ice-edge and cross-ice-edge directions, which in turn determines the strength of the along-ice-edge jet and cross-ice-edge velocity. The momentum applied in the along-ice-edge(cross-ice-edge)direction increased(decreased) with larger incident angle, which is favorable condition for producing stronger mesoscale eddies, vice versa. The dissipation rate increases(decreases) with larger(smaller) wavenumber, which enhances(reduces) the jet strength and the strength of the mesoscale eddy. The strong along-ice-edge jet may extend to a deep layer(> 200 m). If the water depth is too shallow(e.g., 80 m), the jet may be largely dampened by bottom drag, and no visible mesoscale eddies are found. The results suggest that the bathymetry and incident wavenumber(magnitude and propagation direction) are important for wave-driven current and mesoscale eddy genesis.  相似文献   

Household dependence on solid cooking fuels in Peru: An analysis of environmental and socioeconomic conditions     

《Global Environmental Change》2019

Solid fuel use is linked with adverse effects on the environment and human health. Yet, solid fuels remain an important energy source for households in developing countries. Even when country-level dependence on solid fuels is modest, there is often significant variation in within-country patterns of solid fuel use. This study examines a range of environmental and socioeconomic conditions to understand the relationship between them and household energy use within a country. While our results are derived from a study of regional patterns of solid fuel dependence in Peru, the contribution of this study is broad: variables that we include in our models of households’ fuel choice decisions are likely to shape such decisions in most developing countries. Our findings indicate that environmental conditions, such as elevation and forest cover, are associated with solid fuel use. Socioeconomic factors, including urbanization, poverty and female literacy, are similarly important. In addition, we identify nuanced links between types of female employment and indigenous population, on the one hand, and solid fuel use, on the other.  相似文献   

GRAPES全球集合预报系统模式扰动随机动能补偿方案初步探究   总被引：10，自引：5，他引：5       下载免费PDF全文

彭飞  李晓莉  陈静  李红祺 《气象学报》2019,77(2):180-195

为了体现次网格尺度能量升尺度转换过程中存在的不确定性, 文中将随机动能补偿(Stochastic Kinetic Energy Backscatter, SKEB)方案应用于GRAPES(Global/Regional Assimilation and Prediction System)全球集合预报系统(GRAPES-GEPS), 以更好地表征模式误差并且增大集合离散度。使用的SKEB方案基于具有一定时、空相关特征的随机型以及由数值扩散导致的局地动能耗散率来构造随机流函数强迫。并根据流函数与水平风速旋转分量的关系, 将SKEB方案中的流函数强迫转化为适用于GRAPES全球模式的水平风速扰动。结果表明, SKEB方案的使用一方面能够提高GRAPES对大气动能谱的模拟能力; 另一方面能够改善GRAPES-GEPS的集合离散度与集合平均误差的关系, 增加了集合离散度, 并在一定程度上减小了集合平均误差, 尤其是在热带地区这种改进更为显著。而且该方案使得热带地区连续分级概率评分(CRPS评分)显著减小。就降水预报而言, 从Brier评分与相对作用特征面积(AROC, Area under the Relative Operating Characteristics)的结果来看, SKEB方案有助于改善中国地区小雨[0.1 mm, 10 mm)、中雨[10 mm, 25 mm)与大雨[25 mm, 50 mm)量级降水的概率预报技巧, 而对暴雨[50 mm, ∞)量级降水预报技巧影响很小(24 h降水量)。总体上, 模式扰动随机动能补偿方案提高了GRAPES-GEPS的概率预报技巧。   相似文献   

Characteristics and evolution of a coastal mesoscale eddy in the Western Bay of Bengal monitored by high-frequency radars     

《Dynamics of Atmospheres and Oceans》2019

  相似文献   

Comparing future patterns of energy system change in 2 °C scenarios with historically observed rates of change     

《Global Environmental Change》2015

This paper systematically compares modeled rates of change provided by global integrated assessment models aiming for the 2 °C objective to historically observed rates of change. Such a comparison can provide insights into the difficulty of achieving such stringent climate stabilization scenarios. The analysis focuses specifically on the rates of change for technology expansion and diffusion, emissions and energy supply investments. The associated indicators vary in terms of system focus (technology-specific or energy system wide), temporal scale (timescale or lifetime), spatial scale (regional or global) and normalization (accounting for entire system growth or not). Although none of the indicators provide conclusive insights as to the achievability of scenarios, this study finds that indicators that look into absolute change remain within the range of historical growth frontiers for the next decade, but increase to unprecedented levels before mid-century. Indicators that take into account or normalize for overall system growth find future change to be broadly within historical ranges. This is particularly the case for monetary-based normalization metrics like GDP compared to energy-based normalization metrics like primary energy. By applying a diverse set of indicators alternative, complementary insights into how scenarios compare with historical observations are acquired but they do not provide further insights on the possibility of achieving rates of change that are beyond current day practice.  相似文献   

Retrieval of outgoing longwave radiation from COMS narrowband infrared imagery     

Myung-Sook Park  Chang-Hoi Ho  Heeje Cho  Yong-Sang Choi 《大气科学进展》2015,32(3):375-388

Hourly outgoing longwave radiation(OLR) from the geostationary satellite Communication Oceanography Meteorological Satellite(COMS) has been retrieved since June 2010. The COMS OLR retrieval algorithms are based on regression analyses of radiative transfer simulations for spectral functions of COMS infrared channels. This study documents the accuracies of OLRs for future climate applications by making an intercomparison of four OLRs from one single-channel algorithm(OLR12.0using the 12.0 μm channel) and three multiple-channel algorithms(OLR10.8+12.0using the 10.8 and 12.0 μm channels; OLR6.7+10.8using the 6.7 and 10.8 μm channels; and OLR All using the 6.7, 10.8, and 12.0 μm channels). The COMS OLRs from these algorithms were validated with direct measurements of OLR from a broadband radiometer of the Clouds and Earth's Radiant Energy System(CERES) over the full COMS field of view [roughly(50°S–50°N, 70°–170°E)] during April 2011.Validation results show that the root-mean-square errors of COMS OLRs are 5–7 W m-2, which indicates good agreement with CERES OLR over the vast domain. OLR6.7+10.8and OLR All have much smaller errors(～ 6 W m-2) than OLR12.0and OLR10.8+12.0(～ 8 W m-2). Moreover, the small errors of OLR6.7+10.8and OLR All are systematic and can be readily reduced through additional mean bias correction and/or radiance calibration. These results indicate a noteworthy role of the6.7 μm water vapor absorption channel in improving the accuracy of the OLRs. The dependence of the accuracy of COMS OLRs on various surface, atmospheric, and observational conditions is also discussed.  相似文献   

Public values for energy system change     

《Global Environmental Change》2015

In this paper we discuss the importance of framing the question of public acceptance of sustainable energy transitions in terms of values and a ‘whole-system’ lens. This assertion is based on findings arising from a major research project examining public values, attitudes and acceptability with regards to whole energy system change using a mixed-method (six deliberative workshops, n = 68, and a nationally representative survey, n = 2441), interdisciplinary approach. Through the research we identify a set of social values associated with desirable energy futures in the UK, where the values represent identifiable cultural resources people draw on to guide their preference formation about particular aspects of energy system change. As such, we characterise public perspectives as being underpinned by six value clusters relating to efficiency and wastefulness, environment and nature, security and stability, social justice and fairness, autonomy and power, and processes and change. We argue that this ‘value system’ provides a basis for understanding core reasons for public acceptance or rejection of different energy system aspects and processes. We conclude that a focus on values that underpin more specific preferences for energy system change brings insights that could provide a basis for improved dialogue, more robust decision-making, and for anticipating likely points of conflict in energy transitions.  相似文献