我国海洋环境保护标准化的现状、需求和建议          下载免费PDF全文

王燕  张志锋  姚子伟  高会 《海洋开发与管理》2018,35(4):36-39

海洋环境保护标准化对我国海洋环境保护事业的发展具有重要的技术支撑作用。文章从海洋环境保护标准体系、标准发布和制修订以及标准类别特征等方面,概述我国海洋环境保护标准化的发展现状;分析海洋环境保护标准化的需求,主要包括标准的适用性和有效性有待评估和提升、标准制修订的进程有待加快、监测方法标准的体例和结构有待规范和统一、海洋高新技术标准体系有待建立以及与多学科和其他行业标准有待统筹5个方面。基于此,提出促进和保障海洋环境保护标准化工作发展的4点建议,即建立海洋环境保护标准化工作专家库、健全海洋环境保护标准体系、加强多部门合作和积极参与海洋国际标准化工作。  相似文献   

Revisiting the existence of an effective stress for wet granular soils with micromechanics          下载免费PDF全文

Jérôme Duriez  Richard Wan  Mehdi Pouragha  Félix Darve 《国际地质力学数值与分析法杂志》2018,42(8):959-978

A possible effective stress variable for wet granular materials is numerically investigated based on an adapted discrete element method (DEM) model for an ideal three‐phase system. The DEM simulations consider granular materials made of nearly monodisperse spherical particles, in the pendular regime with the pore fluid mixture consisting of distinct water menisci bridging particle pairs. The contact force‐related stress contribution to the total stresses is isolated and tested as the effective stress candidate for dense or loose systems. It is first recalled that this contact stress tensor is indeed an adequate effective stress that describes stress limit states of wet samples with the same Mohr‐Coulomb criterion associated with their dry counterparts. As for constitutive relationships, it is demonstrated that the contact stress tensor used in conjunction with dry constitutive relations does describe the strains of wet samples during an initial strain regime but not beyond. Outside this so‐called quasi‐static strain regime, whose extent is much greater for dense than loose materials, dramatic changes in the contact network prevent macroscale contact stress‐strain relationships to apply in the same manner to dry and unsaturated conditions. The presented numerical results also reveal unexpected constitutive bifurcations for the loose material, related to stick‐slip macrobehavior.  相似文献   

张力腿平台筋腱支撑浮筒结构设计研究     

王火平  金文学  吕东  范志峰  王立权 《海洋工程》2018,36(3):69-75

在张力腿平台筋腱与海底桩基连接后,需要筋腱支撑浮筒为筋腱提供足够的浮力,保证筋腱在平台运抵工作海域之前不会发生倾覆。针对南海油田自主研发的张力腿平台筋腱实际尺寸及设计要求,设计了适用于1 061 mm(40英寸)筋腱、500米水深的张力腿平台筋腱支撑浮筒,并对筋腱支撑浮筒主要受力进行了分析计算,根据所计算的载荷情况对关键部件进行了有限元仿真分析,验证了结构强度的可靠性,并得到了结构的应力集中点与最大变形点,为筋腱支撑浮筒的结构设计提供了参考。  相似文献   

CATASTROPHIC ECO-ENVIRONMENTAL CHANGE IN THE SONGNEN PLAIN, NORTHEASTERN CHINA SINCE 1900S   总被引：1，自引：1，他引：0  

WANGHai-xia WANZhong-juan YUShao-peng LUOXin-zheng SUNGuang-you 《中国地理科学(英文版)》2004,14(2):179-185

Although the Songnen Plain in the northeastern China was developed relatively late in the temperate zone of the world, its eco-environment has changed greatly. This paper analyzes the changes of land cover and the rates and trends ofdesertification during the past 100 years in the Songnen Plain. According to the macroscopic analysis, we find that the eco-environment in the plain has reached to the threshold of catastrophic change since the 1950s. The Thorn Needle Catastrophic Model was used to determine and validate this conclusion. Human activities, including large-scale construction projects, such as huge dams and dikes, and excessive grazing were the primary factors contributing to regional eco-environmental catastrophe. And irrational reclamation of the wilderness also affected the eco-environmental change. The results reveal the complex human-land interactions.  相似文献   

用遗传算法对自动控制系统数学模型寻优     

万月珍  廖成旺 《大地测量与地球动力学》2001,21(2):87-93

探讨用遗传算法对数学模型进行优化。考虑到控制系统稳健性的要求 ,用遗传算法寻找出控制系统最佳稳定域 ,实现控制系统数学模型的寻优。阐述了用遗传算法求解问题的步骤和参数的取值 ,并用仿真实验对优化结果进行了检验。结果表明 :在控制系统数学模型的优化中 ,遗传算法具有其他算法无可比拟的优越性。  相似文献   

The Dependence of Water Exchanges between the Kuroshio Water and Its Surroundings on the Characteristics of the Kuroshio‘s Meanders     

姜华  吴德星  万修全 《中国海洋湖沼学报》2003,21(4):335-344

Observation of fluid parcel pathways in the Kuroshio Stream revealed a striking crossstream pattern associated with the Kuroshio‘‘ s meanders. In order to understand the observed pattern, a two-dimensional kinematic model of a meandering jet was developed which could be used to examine the relationship between streamfunction patterns and fluid parcel trajectories. The experiments designed to investigate the dependence of the water exchanges between the Kuroshio water and its surroundings on the characteristics of the Kuroshio‘‘s meanders involved the downstream speed,phase speed and the amplitude of other propagating waves. The results suggested that fluid parcels could cross the meandering jet to and fro; and that the water exchanges between the Kuroshio and its surroundings increased with a) increasing meander amplitude, b) decreasing downstream speed, and c) increasing wave phase speed. The results also showed that when the meandering jet was disturbed by other propagating waves, more effective water exchanges could be induced.  相似文献   

A note on the algorithm of symplectic integrators     

Xin Wu  Tian-Yi Huang  Hong Zhang  Xiao-Sheng Wan 《Astrophysics and Space Science》2003,283(1):53-65

For a Hamiltonian that can be separated into N+1(N\geq 2) integrable parts, four algorithms can be built for a symplectic integrator. This research compares these algorithms for the first and second order integrators. We found that they have similar local truncation errors represented by error Hamiltonian but rather different numerical stability. When the computation of the main part of the Hamiltonian, H ₀, is not expensive, we recommend to use S ^* type algorithm, which cuts the calculation of the H ₀ system into several small time steps as Malhotra(1991) did. As to the order of the N+1 parts in one step calculation, we found that from the large to small would get a slower error accumulation. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

A moment method for radiative transfer in an anisotropically-scattering slab medium with space-dependent albedoω(x)     

S. J. Wilson  F. S. Wan 《Astrophysics and Space Science》1987,137(1):107-113

The moment method is used to solve the radiative transfer problem in an anisotropic scattering plane medium with arbitrary space-dependent albedo(x). The results are compared with those obtained recently by Cengel and Özisik.  相似文献   

Case history of controlling a landslide at Panluo open-pit mine in China     

Zuoan Wei  Guangzhi Yin  Ling Wan  Louyan Shen 《Environmental Geology》2008,54(4):699-709

Controlling of landsides safely and economically is a great challenge to mine operators because landslides are major geological problems especially in open-pit mines. In this paper, a case history at Panluo open-pit mine is presented in detail to share the experiences and lessons with mine operators. Panluo open-pit mine is located in the southwestern Fujian province of China. It is the largest open-pit iron mine in the Fujian province and was planned in 1965 and is in full operation from 1978. In July 1990, an earthquake of magnitude 5.3 in Taiwan Strait and big rainstorms impacted the mine slope, causing tension cracks and rather large-scale failures, and forming a U-shaped landslide. Total potential volume was estimated to be up to 1.0 × 10⁶ m³. This directly threatened the mine production. In order to protect the mine production and the dwellers’ safety around, a dynamic comprehensive method was implemented including geotechnical investigations, in-situ testing and monitoring, stability analysis, and many mitigation and preventive measures. These measures slowed down the development and further occurrence of the landslide. The results showed that the landslides were still active, it was slowed with the control measures and moved rapidly with rainfall and mining down. However, no catastrophic accidents occurred and the pit mining was continued till it was closed at the elevation of 887 m in 2000. As a successful case of landslide control at an open-pit mine for 10 years, this paper reports the controlling measures in details. These experiences of landslide control may be beneficial to other similar mines for landslide control.  相似文献   

Triassic Nb-enriched basalts, magnesian andesites, and adakites of the Qiangtang terrane (Central Tibet): evidence for metasomatism by slab-derived melts in the mantle wedge   总被引：10，自引：0，他引：10  

Qiang Wang  Derek A. Wyman  Jifeng Xu  Yusheng Wan  Chaofeng Li  Feng Zi  Ziqi Jiang  Huaning Qiu  Zhuyin Chu  Zhenhua Zhao  Yanhui Dong 《Contributions to Mineralogy and Petrology》2008,155(4):473-490

New chronological, geochemical, and isotopic data are reported for Triassic (219–236 Ma) adakite-magnesian andesite-Nb-enriched basaltic rock associations from the Tuotuohe area, central Qiangtang terrane. The adakites and magnesian andesites are characterized by high Sr/Y (25–45), La/Yb (14–42) and Na₂O/K₂O (12–49) ratios, high Al₂O₃ (15.34–18.28 wt%) and moderate to high Sr concentrations (220–498 ppm) and ε_ND (t) (+0.86 to +1.21) values. Low enrichments of Th, Rb relative to Nb, and subequal normalized Nb and La contents, and enrichments of light rare earth elements combine to distinguish a group of Nb-enriched basaltic rocks (NEBs). They have positive ε_ND (t) (+2.57 to +5.16) values. Positive correlations between Th, La and Nb and an absence of negative Nb anomalies on mantle normalized plots indicate the NEBs are products of a mantle source metasomatized by a slab melt rather than by hydrous fluids. A continuous compositional variation between adakites and magnesian andesites confirms slab melt interaction with mantle peridotite. The spatial association of the NEBs with adakites and magnesian andesites define an “adakitic metasomatic volcanic series” recognized in many demonstrably subduction-related environments (e.g., Mindanao arc, Philippines; Kamchatka arc, Russia; and southern Baja California arc, Mexico). The age of the Touhuohe suite, and its correlation with Triassic NEB to the north indicates that volcanism derived from subduction-modified mantle was abundant prior to 220 Ma in the central Qiangtang terrane.  相似文献