吉尼系数的计算及正态分布的吉尼系数

本文给出了吉尼系数的一般计算公式 ,推导出正态分布的吉尼系数渐进无偏估计 ,并以实例对比了传统的吉尼系数的算法——万分法与本文中提出的估计方法。     

三阶海浪波高分布及其应用

在三阶海浪非线性波高分布模式的基础上，引进描述分布函数结构形式的重要统计量，即概率分布的离差系数与偏差系数。给出这两个统计量与非线性控制参数之间的解析关系式，从而给出了反映风浪不同状态下的波高分布特征。与传统的瑞利分布相比，本文的结果有更广泛的实用意义。并把理论结果应用于黄河口波浪统计学的研究。     

三阶海浪波高分布其应用

在三阶海浪非线性波高分布模式的基础上，引进描述分布函数结构形重要统计量，即概率分布的离差系数与偏差系数。与偏差系数。给出这两个统计量与非线性控制参数之间的解析关系式，从而给出了反映风浪不同状态下的波高分布特征。与传统的瑞利分布相比，本文的结果有更广泛的衫意义。并把理论应用于黄河口波浪统计学的研究。     

一阶非线性泛函方程解的振动性(英文)

考虑两类带有分布型超前或滞后量的方程 (Ⅰ)x'(t)=a(t)x(t)+φ, (Ⅱ)x'(t)=a(t)x(t)-φ.其中β(t)>a(t),t+a(t)→∞(t→∞),f(x)和φ(u)是满足某些条件的非线性函数。 本文给出了方程(Ⅰ)和(Ⅱ)的所有解振动的若干充分性判定定理。作为应用,我们又讨论了如下方程的振动性,并给出了相应的判定准则。 (Ⅲ)x'(t)=a(t)x(t)+φ[sum from i=1 to n a_i(t)f(x(t+τ_i(t)))], (Ⅳ)x'(t)=a(t)x(t)-φ[sum from i=1 to n a_i(t)f(x(t+τ_i(t)))] 本文的结果是张炳根的若干结果的推广。     

浮体间距对多浮体系统水动力系数的影响

根据三维线性势流理论，采用格林函数法，对多浮体系统的水动力系数进行了数值分析。数值算例中给出了在固定波频下水动力系数与浮体间相对位置关系曲线。水动力系数的变化幅度随着浮体间距离增大而变小。随着浮体间距的变化，水动力系数极值的出现具有明显的规律，相邻的极大值(或极小值)的间距为半个波长或一个波长。     

Pascal函数矩阵的进一步推广及应用

通过改变矩阵元素得到Pascal函数矩阵的一种推广形式Pn[f(t)],运用矩阵相关理论讨论其代数性质及指数展开形式,由Pn[f(t)]的逆给出1个反演关系,借助指数发生函数,得到包含二项式型多项式、Hermite多项式与Euler多项式等的一些组合恒等式;最后,给出了Pn[f(t)]的2种不同形式的推广。     

南沙群岛海域近海面粗糙度、中性曳力系数及总体交换系数研究

根据 1 994年 9月 1 8— 30日南沙群岛海域渚碧礁的近海面大气湍流观测实验资料 ,分别计算了该海域光滑海面和粗糙海面上的空气动力粗糙度 (z0 )、中性曳力系数 (CDN)。利用Brutsaert的假定 ,推导了一组求取标量粗糙度 (zT,zQ)、整体输送系数 (感热交换系数CHN、水汽交换系数CEN)的公式。在此基础上分别计算和分析了该海域近海面光滑海面和粗糙海面上z0 ,zT,zQ,CDN,CHN,CEN 及它们关于水平风速u分量的分布 ,并得到了一些有意义的结论。     

温度和浓度对氯化钾溶液电导率与35‰(Cl19.3740‰)的标准海水的电导率之比的影响

测定了15℃和24℃相同温度下己知浓度为K的KCl溶液与标准海水电导率的比值Z_(k,t),Z_(,15),在0.96到1.04之间。发现Z_(N,15)=1的标准浓度(N或K_N)为K_N=32.4356gKCl/kg溶液。测量了在15℃或30℃范围内温度对Z_(N,t)的影响,以Z_(15)的函数和反函数关系给出了KCl浓度的方程,以Z_(24)的函数关系给出了Z_(15)/Z_(24)的方程,(用实验室盐度计对KCl和海水进行比较)和以温度的函数关系给出了Z_(N,t)。     

波浪在泥床上衰减

本文用长江口航道淤泥进行室内波浪试验研究,得到波高在泥床上传播时沿程按指数函数衰减:H_l/H=exp[-K(l/L)~n]。函数的幂数n和系数K都是相对泥床厚度(D_s/D)、泥床含沙体积比(S_v)的函数,系数k还与波坦(L/D)和相对水深(D/H)有关。本文还探讨了波浪衰减与泥床波动、水体含沙浓度分布的关系,获得了波浪对泥床作用所产生泥沙运动的一些规律和特点。     

二阶微分方程解的渐近性的讨论

考虑如下的二阶方程 其中X(t,x,)是定义在域H:{0≤t< ∞,-∞0,n>0,f(t)为连续函数,f(t)≠0下讨论了方程(X)的不同类型解的渐近性态,给出了各种渐近解存在的充分必要条件。     

粤港澳大湾区海岛空间分布特征探析

海岛是海洋资源开发利用价值的核心内容之一。为合理保护及开发利用粤港澳大湾区海岛资源,促进海岛产业布局优化,从海岛资源空间分布角度出发,探析海岛在粤港澳大湾区发展中重点平台的作用。以粤港澳大湾区纳入中国海域海岛标准名录的850个海岛为研究对象,在对其地理坐标、陆域面积等基础数据进行数理统计的基础上,通过ArcGIS软件平台,采用最邻近距离法、核密度估计法、洛伦兹曲线和基尼系数方法,对粤港澳大湾区海岛的空间分布特征进行了分析与研究。结果表明:粤港澳大湾区海岛在空间上趋于集聚分布,呈现总体带状分布,局部组团分布的特点,形成了湾区西部海岛分布带和大鹏湾-大亚湾区、九州列岛区、万山-佳蓬担杆列岛区、川山群岛区4个明显的集聚区;粤港澳大湾区海岛以沿岸岛为主,面积分布呈现不均衡性的特点,基尼系数达0.58。     

斜抽运无机液体激光器的流场热分布

激光二极管斜抽运的多增益段串接的液体激光器能够明显地提高激光光束质量、获得较高的输出功率.针对斜抽运子增益段工作时所涉及的流动、传热和壁面耦合,建立了计算子增益段流场热分布的流-热-固耦合模型,应用有限单元法完成了其瞬态流场热分布的数值模拟.该方法排除了不精确的换热系数对计算结果的影响,使得换热系数不再是计算的先决条件,而只是计算结果之一;并且为评价流道形状、流速、吸收系数等因素对流场热的影响,以及进一步改进和控制液体激光介质的流场热分布,提供了可靠的分析方法.数值模拟研究表明:换热系数是空间位置的函数;     

立管-水平板结构消浪特性试验研究

在现有的矩形方箱和透空结构的基础上,提出一种由立管和水平板组合而成的消浪结构。利用波浪水槽物理模型试验,测试该结构在单向规则波作用下的消浪性能。分别探讨了其单排布置和双排布置时的透射系数随结构宽度、相对吃水深 度、相对间距等因素的变化规律。结果表明：单排布置时,透射系数随结构宽度的增大而减小,总体上随吃水深度的增大而减小;双排布置时,透射系数相对总宽度相同的单体结构减少 10 %,透射系数随吃水深度的增大而减小,前后间距对透射系数的影响不明显。对试验结果数据进行曲线拟合,得到了透射系数关于各影响因素的函数表达式。     

辽东湾水体吸收系数区域性半分析反演算法

水体吸收系数是影响水体光场分布的重要参数,在水色遥感探测中受到广泛关注。本文利用2012年9月辽东湾区域航次调查数据分析该区域水体各组分吸收系数的分布情况,结果表明,辽东湾水体中浮游植物含量相对较高。并利用该航次数据,建立了区域性半分析算法,该算法基于相邻波段间固有光学量的线性关系,首先通过遥感反射率反演得到550 nm波段的水体总吸收系数,再通过后向散射波段相关关系外推得到其他波段的总吸收系数。经独立测试数据检验,3个波段(412、443、550 nm)总吸收系数反演的平均相对误差分别为19.71%,17.99%,9.35%,说明区域性半分析算法能较好地估算研究区域的水体总吸收系数。本文还通过引入随机误差对算法稳定性进行了检验,结果表明算法具有较好的稳定性。     

渗透率变异系数的几种计算方法——以麻黄山西区块宁东油田2、3井区为例

渗透率变异系数VK反映样品偏离整体平均值的程度,是评价储层宏观非均质性的最重要参数。介绍了三种渗透率变异系数的计算方法：统计学方法、Dykstra H方法和洛伦兹曲线法,并用三种方法分别计算了宁东油田2、3井区的延8和延9层的渗透率变异系数,比较了三种方法的优缺点和适用范围。实践应用表明,洛伦兹曲线法比较适合本地区的研究,因为它所求出的VK值在0和1之间,具有较强的可比性,能很明确的反应各层位非均质性的程度,而且适合任何分布类型的油藏;统计学方法计算的渗透率变异系数在0~∞之间,用这种方法计算的VK很难建立起该油藏非均质程度的概念;Dykstra H方法适用范围很小,仅适应于渗透率接近于呈对数正态分布的油藏,对本区不太适合。     

A rapid assessment method for calculating the drag coefficient in wave attenuation by vegetation

Vegetation in wetlands is a large-scale nature-based resource that can provide multiple benefits to human beings and the environment,such as wave attenuation in coastal zones.Traditionally,there are two main calibration approaches to calculate the attenuation of wave driven by vegetation.The first method is a straightforward one based on the exponential attenuation of wave height in the direction of wave transmission,which,however,overlooks the crucial drag coefficient (C_D).The other method is in accordance with more complicate equations for predicting the damping factor,which is regarded as a function of C_D.In this study,a new relation,combining these above two conventional approaches,is proposed to predict the C_D in an operative approach.Results show that values yielded by the new assessment method perform a strong linear relationship with a collection of historical observations,with a promising R~2 value of 0.90.Besides,the linear regression derives a new predictive equation for the bulk drag coefficient.Additionally,a calibrated value of 4 for the empirical plant drag coefficient(C_P) is revealed.Overall,this new equation,with the superiority of the convenient exponential regression,is expected to be a rapid assessment method for calculating wave attenuation by vegetation and predicting the drag coefficient.     

Characteristics of water masses and bio-optical properties of the Bering Sea shelf during 2007–2009

The hydrographic and bio-optical properties of the Bering Sea shelf were analyzed based on in-situ measurements obtained during four cruises from 2007 to 2009. According to the temperature and salinity of the seawater, the spring water masses on the Bering Sea shelf were classified as the Alaskan Coast Water, Bering Sea Shelf Water, Anadyr Water, Spring Mixed Layer Water, Remnant Winter Water, and Winter Water, each of which had varying chlorophyll a concentrations. Among them, the highest chlorophyll a concentration occurred in the nutrient-rich Anadyr Water ((7.57±6.16) mg/m3 in spring). The spectrum-dependent diffuse attenuation coefficient (K_d(λ)) of the water column for downwelling irradiance was also calculated, exhibiting a decrease at 412–555 nm and then an increase within the range of 0.17–0.48 m–1 in spring. Furthermore, a strong correlation between the chlorophyll a concentration and the attenuation coefficient was found at visible wavelengths on the Bering Sea shelf. Spatially, the chlorophyll a concentration was higher on the northern shelf ((5.18±3.78) mg/m3) than on the southern shelf ((3.64±2.51) mg/m3), which was consistent with the distribution of the attenuation coefficient. Seasonally, the consumption of nutrients by blooms resulted in minimum chlorophyll a concentration ((0.78±0.51) mg/m3) and attenuation coefficient values in summer. In terms of the vertical structure, both the attenuation coefficient and the chlorophyll a concentration tended to reach maximum values at the same depth, and the depth of the maximum values increased as the surface temperature increased in summer. Moreover, an empirical model was fitted with a power function based on the correlation between the chlorophyll a concentration and the attenuation coefficient at 412–555 nm. In addition, a spectral model was constructed according to the relationship between the attenuation coefficients at 490 nm and at other wavelengths, which provides a method for estimating the bio-optical properties of the Bering Sea shelf.     

Regional disparities in China's marine economy

Understanding the performance of each coastal area as it develops is the primary task of policy-makers in a marine economy; however, quantitative regional differences in China's marine economy have not been empirically examined. This paper offers a methodological contribution by applying a series of techniques, including the variation coefficient, Gini coefficient, and Theil index decomposition, to illustrate the relative differences among coastal areas. Additionally, the coastal areas of China were divided into two categories to reveal the provincial differences and regional disparities in China's marine economy. The results show that although the numerical economic differences in Gross Ocean Product (GOP) among coastal areas have increased significantly during the 21st century, the gaps among coastal regions have gradually decreased. In addition, China's marine economy presents three levels of regional development (developed, medium-developed, and developing). The results of the Theil index decomposition show that the overall difference in China's marine economy is derived mainly from differences within the three macro marine economic regions; these differences account for more than 95% of the overall difference. Furthermore, the underlying reasons for and driving mechanism of regional differences in China's marine economy can be illuminated in terms of differences in natural resource endowments and geographic locations; industrial agglomeration and diffusion; changes in regional development policy; and foreign investment. These findings offer basic data support and policy recommendations for marine economy management at the national and regional levels.