共查询到19条相似文献，搜索用时 437 毫秒
1.
给出图的点团二分图和边团二分图具有强Helly性质的充分必要条件,证明了使点团二分图具有强Helly性质的图的团贪心性和团不变性。 相似文献
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使用甲壳胺人工皮复盖Ⅱ°烧伤新鲜创面,深Ⅱ°及Ⅲ°削切痂创面,供皮区创面共20例、25个创面,发现有减少创面渗出,减少疼痛,减少换药次数,节省敷料,防止加深,比传统方法提前2～3d(天)治愈的优点. 相似文献
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利用中国地区435个台站1961—2002年逐日平均温度序列,将温度变化发生在9天时间尺度上的特征编码在网络中,通过研究二分图温度网络(BGT网络)中节点与项目的关系,揭示出9天时间尺度上温度变化的特征及其在空间上的拓扑统计性质.网络中各节点RRRD, RrDD, eeed, DRRD, DDRR等所代表的温度波动模态在网络中异常频发,对9天尺度温度变化的预报有一定的指导意义.统计网络的节点度分布,集群系数等拓扑结构特征量,发现BGT网络服从正态分布特征.BGT网络项目内节点度的多样性大体上 相似文献
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《中国海洋大学学报(自然科学版)》2017,(Z1)
主要考虑求解等式约束不定最小二乘校正问题。基于不定对称矩阵的反三角矩阵分解,给出了求解不定最小二乘更新问题的一种数值方法。该算法主要通过正交相似变换将对应的增广矩阵化为块下反三角形式,使得原线性系统变得更易于求解,同时也给出了原问题和校正问题的解之间的关系。数值实验表明本文给出的数值方法是有效的,可以得到较精确的近似解。 相似文献
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大地构造图反映着作者对大地构造演化过程和动力机制的理解,往往以某种大地构造观点为指导。经历了20世纪七八十年代百家争鸣的大地构造编图时代以后,随着板块构造理论的引进,各家观点在承认板块构造理论的同时,表述各有侧重。地质地球物理调查是大地构造编图的资料基础,近年来,调查资料无论在数量上还是在精度上,都有较大的突破。但是,海区的大地构造编图还存在一些问题,就是海区调查研究基础与陆区相比还相对薄弱,近十年来海区的地调科研成果也没有表现在大区域的,尤其是涵盖全海区或整个中国海陆的大地构造图上。多种地球物理资料的综合研究,可以作为中国海陆大地构造对比和研究的纽带,地质、地球物理和地球化学方法和资料的综合应用,可作为大地构造编图的重要基础。从一个海洋地质构造工作者的角度,在阐释对我国大地构造编图的历史、观点、资料、成果及努力方向理解的基础上,希望通过正在执行的"中国海陆大地构造格架图",为编制中国大地构造图的思路做一个新探索。 相似文献
6.
一类非线性系统次优控制的灵敏度法 总被引：1，自引：0，他引：1
本文研究一类非线性定常系统的次优控制问题。通过在系统中引入 1个灵敏度参数并将系统变量关于灵敏度参数展开 Maclaurin级数 ,使求解最优控制的非线性两点边值问题化为一族线性两点边值问题。利用截取最优控制级数的有限项求得系统的次优控制律。仿真实例表明 ,该方法对非线性系统次优控制律的设计是有效的 相似文献
7.
国际规定的图幅是按经线和纬线来划分由的,由经纬线围成各梯形图图幅,其编号由该图幅所在的行号与列号组合而成,看似无缝拼接。在海涂地形图的形成过程中,用现势数据和历史数据比对,历史成果图与现势图拼接时,图上的地形出现叠加或分离的现象。图幅划分与高斯分带是两种不同的投影概念,前者面积不变,角度改变,使椭圆线成为弧线和直线;后者除了中央子午线不变外其他均有改变,使各带的变形规律相同,误差互不传递,所以不同中央子午线的图进行拼接会出现分离或叠加现象,这并非测量或图形误差所致。此外,只要找出分幅规律性,各比例尺图号与经纬度可以通过图解或计算获得,图上任何点坐标能计算各种比例尺图号及图廓经纬度。 相似文献
8.
本文研究任意倾角的线性倾斜海底上的定常风海流问题。此问题归结为求解无界角域内的亥姆霍兹方程边值问题。通过保角变换构造出了该问题的格林函数,从而得出解式。最后对典型海域的流场进行了数值计算,并给出断面上的流场图。 相似文献
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文中介绍陆地影像图与港口航道图镶嵌的制图工艺,影像图与港口航道图镶嵌后的成图质量评价。简单阐述了作者在绘制该图种过程中的一些体会,以及影像图取代现有港口航道图上陆地地形的可行性。 相似文献
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The problem of propagation of obliquely incident surface water waves over a pair of asymmetrical rectangular trenches in a channel of finite depth is examined for its solution. The mathematical problem is handled for its numerical solution with the aid of a system of singular integral equations of first kind. The resulting integral equations are solved numerically by using suitably designed polynomial approximations of the unknown functions. System of linear algebraic equations is obtained by utilizing the zeros of Chebyshev polynomial of first kind as collocation points and hence the occurrence of ill-conditioned matrix is avoided. The effectiveness of the pair of trenches is studied by analyzing the physical quantities namely the reflection and transmission coefficients. As a special limiting case, the results for a single trench problem are derived and are found to be in excellent agreement with the results available in the literature. The effect of various parameters are analyzed through different graphs for a pair of asymmetrical trenches. The energy balance relation is derived and used to check the accuracy of numerical results. 相似文献
12.
马克娴 《中国海洋大学学报(自然科学版)》1989,(Z3)
通过30例烧伤病人用甲壳胺人工皮覆盖46个创面,获得良好效果,成功29例,失败1例.观察其柔软性、耐久性、粘附性、抗感染作用、促进上皮化作用都较好.在耐久性和占位性方面都优于国内外同类产品,是一种较理想的烧伤创面覆盖物.它的使用平均可缩短创面愈合时间3.5天,并减少换药,简化护理,节约敷料,使用方便,对各级医院有较大的实用性. 相似文献
13.
Statics of a three component mooring line 总被引：1，自引：0，他引：1
Catenary equations are solved for a three component mooring made up of two lines, connected at a point buoy or sinker where water depth and fairlead tension are given. This configuration is typical of deep water moorings and solutions are required for preliminary design of mooring systems and measurement of stability in service of moored floating platforms. The problem is transformed to a single polynomial equation of degree eight and is solved by Laguerre's iteration. Where there is no buoy or sinker the equation reduces to a quartic and can be solved in closed form. Elongation of the lines is shown to be equivalent to small uncertainties in the weights per unit length. The method is computationally efficient. 相似文献
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全国临床研究组 《中国海洋大学学报(自然科学版)》1989,(Z3)
1989年4月～1990年10月期间,由全国组成的临床研究组10个烧伤单位对CHIMEHERB人工皮进行全面临床研究.研究目的是:(1)探索应用方法.(2)明确适应症.(3)评价疗效.在260例烧伤病人中,共应用365个不同类型创面,有效率为90.5％,其中优良率为79.7％.研究指出,CHIMEHERB人工皮的性能适合于作为暂时性创面覆盖物,对上皮生长具有有利影响,未发现占位和排斥现象,以及过敏和其他不良反应.主要适用于(1)供皮区,(2)Ⅱ°烧伤创面.(3)深Ⅲ°烧伤脱痂和削痂创面.(4)网状植皮和小皮片(或条状)植皮创面。(5)残余肉芽创面.亦可用于切痂创面.但不适于深Ⅱ°新鲜创面和切痂嵌皮.感染创面应用CHIMEHERB人工皮应结合抗感染措施.应用人工皮创面需良好包扎与固定.人工皮下渗出物多需引流. 相似文献
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从1989年4月～1990年10月,我科在69例病人中使用CHIMEHERB人工皮,覆盖治疗了供皮区,Ⅱ°烧伤创面、脱痂创面的残余肉芽创面.临床应用表明:CHIMEHERB人工皮能加快创面的愈合,是目前较好的一种创面覆盖物,用人工皮覆盖创面2～3天后,人工皮干燥,不需再换药,可减轻病人的痛苦. 相似文献
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Abstract. The so-called 'covering behaviour' of echinoids is known to vary with habitat according to the types of covering items available, but the full extent of the role played by habitat characteristics in this behaviour is not known. Moreover, whether or not different species inhabiting similar environmental conditions and habitats also show similar patterns of this particular behaviour has yet to be investigated. In this study, two prominent west coast echinoid species, Paracentrotus lividus and Strongylocentrotus purpuratus , were examined with respect to covering behaviour and spatial organisation. Populations of both species are found in exposed intertidal zones, occupying boreholes within tidepools. Important similarities were found in the spatial organisation of both species' populations, with lowest densities in upper shore pools. However, the size distributions of the two populations differed significantly; P. lividus within upper shore pools were significantly larger than those in mid or lower shore pools, whereas S. purpuratus on the lower shore were significantly larger than those at other shore heights. We found significant between-species variability in covering item use, although the number of covering items available at both sites was not significantly different. For example, greater densities of covering items were used by P. lividus than by S. purpuratus . We also found that the percent of echinoid surface area covered varied significantly in space for both species. These data emphasise the complex and multifaceted nature of covering behaviour, but most importantly, they also strongly suggest that habitat characteristics can only partly explain the extent of this behavioural variability amongst echinoid species. 相似文献
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《Marine Models》2002,2(1-4):19-34
Accurate density calculation that includes pressure effects is achieved with negligible computational cost in the context of three-dimensional ocean modelling. Local linear (or quadratic) fits to the full UNESCO (Anon, 1981) equation of state can be used in many model applications where the potential temperature and salinity at a model grid point vary slightly in each model time step. The local polynomial fit is achieved by computing a Taylor series expansion about a local reference state. The terms in the Taylor series are calculated analytically for optimal accuracy and minimal computational cost. All calculations can be done with single precision arithmetic, without compromising accuracy. In a three-dimensional nonhydrostatic ocean model applied to a deep convection problem, the local density calculation reduced the total computational cost of the model by 7% relative to that when the full UNESCO density calculation was used. The computational advantage is 15% for an application in which the nonhydrostatic part of the calculation is turned off. The computational advantage is, however, a function of the nature of both the model being used and the problem being solved.The principal algorithms are coded in Fortran 90, fortran 77, and as Matlab functions. The complete set of routines and test programs is coded in Fortran 90. 相似文献
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A survey of the literature reveals that the title problem has not been previously solved. The fundamentals frequency of transverse vibration of the orthotropic structural element is determined by expanding the displacement amplitude function in terms of simple polynomial coordinate functions which satisfy identically the essential boundary conditions and approximately some of the natural edge requirements.The Ritz method is then used to generate the frequency equations. 相似文献