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孔庆凯 《山东海洋学院学报》1983,13(1):89-99
(一)引言 考虑如下的二阶方程 X=X（t,x,x）其中X（t,x,x）是定义在域H：{0≤t＜ ∞,-∞＜x∞＜ ∞,-∞＜x＜ ∞}上的连续函数，且满足解的存在唯一性条件和对初值的连续依赖性条件，x(t，x,x)是关于x的不减函数。 相似文献
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熊凤兰 《山东海洋学院学报》1985,15(3):107-114
在普通矩阵的乘积运算下，人们对矩阵的｛1｝一逆，{1，3｝一逆，｛1，4｝一逆；{1，3，4｝一逆的理论已作了详尽的研究。为了将此部分理论引进模糊数学领域，并考虑到它的一些特点，作者在本文借用“*”算子和“V”算子，重新定义了矩阵的{1}一逆，{1，3｝一逆，{1，4}一逆，{1，3，4}一逆，并推出本文所列定理。即得到在“V-*”运算下广义逆的部分理论。 相似文献
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拉丁方正交完全系和常用正交表的简捷构造法 总被引：1，自引：0，他引：1
本文根据两个同阶拉丁方正交的定义和正交表的定义以及有关的数学理论，编制出拉丁方正交完全系和常用正交表的简捷构造法，提供给实验工作者使用并以此加深对拉丁方设计和正交设计的理解和掌握。设正整数ｍ〉２，本文在以下两种情形分别使用不同的方法构造ｍ阶拉丁方正交完全系：（１）ｍ为质数：以自然顺序的第１列为起点，从第２列开始，在列中依次进行数置换；（２）ｍ为质数幂：首先构造一个特定的标准拉丁方作为起点，然后从第 相似文献
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应用色谱－质谱（GC－MS）方法分别鉴定了从广西海涠洲岛水域和海南省陵水县水域采集的莳萝曲网海绵Sigmadocia cymiformis的甾醇类化合物,涠洲岛水域的莳萝曲网海绵所含的旮醇类化合物主要是：胆甾－4，6－二烯3β－醇（1），27－降麦角甾5，22－二烯－3β－醇，（2），胆甾醇（3），（24S）－麦角甾5，22－二烯3β－醇（40，麦角甾5－烯C－3β－醇（5），麦角甾－2，22－二烯－3β－醇（6），豆甾醇（7），β－谷甾醇（8），麦角甾－4，24（28）－二烯－3－酮（9），柳珊瑚甾醇（10）；而陵水县水域的莳萝曲网海绵所含甾醇类化合物主要是：（3），（4），（5），（6），（8），胆甾－2，55－二烯－3β－醇（11），胆旨－3，5－二烯－7－酮（12），这是莳萝曲网海绵中甾醇类化合物组成的首次报道。 相似文献
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依比例、不依比例和半依比例符号数学定义的修改 总被引：1，自引：0，他引：1
定义了一般地图符号后，在此基础上引入地物的真实像，通过地图符号与真实像相同、包含和半包含关系的讨论，分别推导了依比例符号、不依比例符号和半依比例符号数学定义。修改后的定义更能反映三种符号的本质特征和内在联系，定义的表达也更为简捷。 相似文献
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秋刀鱼舷提网渔具性能模型试验与海上实测结果的比较评估 总被引：1，自引：0，他引：1
舷提网是秋刀鱼（Cololabis saira）作业的主要方式之一，由于渔获率较高得到迅速推广。模型试验和海上实测是研究网具性能最为普遍的两种方式，两者试验结果的对比评估对于更好地测定网具作业性能具有十分重要的意义。根据2014年11-12月进行的秋刀鱼舷提网静水槽模型试验以及2015年7-10月和2016年6-10月在"鲁蓬远渔019"号船上进行的秋刀鱼舷提网网具性能测试试验测定的网具数据，采用多元线性回归方法，对网具的沉降深度和提升速度进行了标准化，并利用Bootstrap法分析了舷提网模型试验和海上实测试验结果。结果表明:（1）通过Bootstrap法得出标准化后的实测网最大沉降深度的均值分布范围为20.37~29.54 m，95%置信区间为21.76~28.13 m；模型网网具最大沉降深度均值的范围为26.42~37.58 m，95%置信区间为27.70~36.20 m。实测网网具中部最大沉降深度均值大约是模型网网具中部最大沉降深度均值的0.731~0.783倍。（2）通过Bootstrap法得出标准化后的实测网提升速度的均值分布范围为0.107~0.193 m/s，95%置信区间为0.111~0.191 m/s；模型网网具提升速度均值的范围为0.204~0.316 m/s，95%置信区间为0.207~0.312 m/s。实测网网具中部提升速度均值大约是模型网网具中部提升速度均值的0.591~0.611倍。（3）当假设海流速度为0时，求得实测网网具的平均沉降深度为29.14~41.21 m，约为模型网网衣中部最大沉降深度均值的0.751~0.807倍。（4）30 m和60 m水深的海流速度均对实物网网具中部的沉降深度有所影响，60 m水深的流速影响更加显著（P<0.05）。 相似文献
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基于延绳钓观察员数据的热带太平洋中东部食物网拓扑结构分析 总被引：1，自引：0，他引：1
热带太平洋是金枪鱼类、旗鱼类等渔业的主要作业海域，但目前针对此海域食物网的研究仍十分缺乏。本文根据2017年6月-11月中国金枪鱼科学观察员在热带太平洋中东部海域（13°09''N -34°27''S, 100°03''-176°17''W）采集的鱼类样品，结合胃含物及其他分析方法以35个物种间的摄食关系为基础对此海域的食物网结构进行了分析。拓扑学指标（节点强度，D；中心性指数，BC和CC；拓扑重要性指数，TI1和TI3；关键性指数，K、Kt和Kb）和Key-Player算法（KPP-1和KPP-2）用来筛选关键种，并结合体长数据建立了基于关键种的简化食物网。肯德尔相关性分析和聚类分析结果表明，不同拓扑学指标筛选出的关键种是一致的。大多数关键种与太平洋其他海域的研究结果是相同的，如剑鱼（Xiphias gladius）、长鳍金枪鱼（Thunnus alalunga）、小吻四鳍旗鱼（Tetrapturus angustirostris）头足类和鲭属。移除5个关键种后，食物网将被离散为许多互不连接的部分（F=0.632，FD=0.795，RD=0.957），表明这些物种在维持食物网结构和稳定性中的必要性。物种体长是本研究构建简化食物网时的决定性因素。研究结果有助于提高对热带太平洋食物网结构的认识，同时为进一步的生态系统动力学研究提供科学依据。 相似文献
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Spiridonov E. A. Desherevskii A. V. Vinogradova O. Yu. 《Izvestiya Atmospheric and Oceanic Physics》2020,56(8):845-858
Izvestiya, Atmospheric and Oceanic Physics - From the ERA5 reanalysis data, the time series of the first coefficients ( $$C_{0}^{0}$$ , $$C_{1}^{0}$$ , $$C_{1}^{1}$$ , $$S_{1}^{1}$$ , $$C_{2}^{0}$$... 相似文献
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The Practical Salinity Scale (PSS) 1978 is defined only for salinities within the range 2-42. We have investigated the relationship between mass-determined salinity, electrical conductivity, and temperature for salinities between 0 and 2 with the aim of developing an extension to the Practical Salinity Scale 1978. The paper presents our data, on the basis of which the following correction is proposed to extend the validity of the equations defining the scale to the entire 0-42 range:S=summin{i=0}max{5} (a_{i}+b_{i}f(t))R_{t}^{i/2}-frac{a_{0}}{1 + 1.5x + x^{2}}-frac{b_{0}f(t)}{1+y^{1/2} + y + y^{3/2}} wheref(t)=frac{(t-15)}{1 + k(t-15) x=400R_{t} y=100R_{t} and the constanta_{i}, b_{i} , andk are defind by the Practical Salinity Scale 1978. 相似文献
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The ratiosR_{s,t,o} of electrical conductivity of seawater samples of precisely known salinity to standard seawater at the same temperature have been measured over a wide range of salinities from 0 to42permil S and over the full range of oceanic temperatures from -2 to35deg C. The samples withS<35permil were prepared by accurate weight dilution of standard seawater with distilled water. High salinity samples were prepared by fast evaporation of standard seawater and subsequent weight dilution into the already determined <35permil range. An equation was derived which expresses the S versusR_{s,t,o} relationship very precisely from1-42permil and at all temperatures, i.e.,S = f_{1}(R_{s,t,o}) + f_{2}(R_{s, t,o},t) =Sigma_{n=0}^{5} a_{n}R^{n/2}+ frac{Delta t}{1+kDelta t} Sigma_{n=0}^{5} b_{n}R^{n/2} whereDelta t = t-15deg C,R = R_{s, t.o} ; only the first termf_{1} is required at15deg C. The effeet of temperature on the electrical conductivity of standard seawater was also measured. The ratior_{t} of the conductivity at temperaturet to the conductivity at15deg C (C_{35,t, o}/C_{35,15,o} ) is very aeenrately expressed by a fourth degree equation int . i.e,r_{t}=Sigma_{n=0}^{4} c_{n}t^{n} These two equations are sufficient for all salinity determinations at normal atmospheric pressure. 相似文献
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《Oceanic Engineering, IEEE Journal of》2009,34(4):407-422
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《Oceanic Engineering, IEEE Journal of》1980,5(1):17-21
The ratiosZ_{K,t} of electrical conductivities of potassium chloride (KCI) solutions of known concentration (K ) to standard seawater at the same temperature have been measured at15deg C and24deg C for solutions withZ_{k,15} between 0.96 and 1.04. The "normal" concentration (N or K_{N} ) givingZ_{N,15}= 1 was found to beK_{N} = 32.4356 gKCI/kg solution. The effect of temperature onZ_{N,t} was measured over the range15deg C to30deg C. Equations are given for KCI concentration as a function ofZ_{15} and the inverse function, forZ_{15}/Z_{24} as a function ofZ_{24} (to allow use of a laboratory salinometer for the KCI-seawater comparisons), andZ_{N,t} as a function of temperature. 相似文献
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Systems of identical precisely spaced bubbles or similar monopole scatterers in water-e.g., inflated balloons or thin-walled shells-insonified at frequenciesomega_{SR} dose to their fundamental radial resonanceomega_{0} (bubble) frequency may themselves display resonance modes or superresonances (SR's) [1]. Ordinary single-bubble resonances magnify the local free-field pressure amplitudep_{1} by a factor(ka)^{-1} ,a being the radius andk the wavenumber in water: for air bubbles or balloons in water, this factor is of the order of 70. Under SR conditions each member of the system amplifies the local free-field amplitude by a further factor of order(ka)^{-1} . Depending upon geometry and other constraints, the pressure fieldP_{SR} on the surface and in the interior of each scatterer will then be in the range of10^{3}p_{1} to5 times 10^{3} p_{1} . This paper investigates the sensitivity of this phenomenon to small departures from the ideal model. In particular, it examines the effect of small differences in scatter positioning and volumes in the context of an SR system consisting of two bubbles/balloons close to the boundary of a thin elastic plate overlying a fluid half-space. It is found that, to observe the SR phenomenon, radii and positions should be controlled to within approximately 1/2 percent.P_{SR} is also sensitive to the angle of incidence of the plane wave train. For the simple system examined here, this sensitivity is considerable for either flexural wave trains or volume acoustic waves incident upon the bubble/ balloon pair (doublet). Practical uses of the phenomenon may range from the design of passive high-Q acoustical filter/amplifiers and acoustical lenses to improved source efficiencies. 相似文献
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Rationale for the measurement of open-ocean tsunami signatures are presented, and available pertinent data are reviewed. Models for tsunami signature and background noise are proposed in order to synthesize an optimum tsunami receiver. Using these models, the minimum tsunami amplitude (in cm) to yield the probability of correct tsunami detectionP_{D} = 0.999 and probability of false alarmP_{F} = 10^{-3} is found to be0.718/sqrt{f_{0}} , wheref_{0} is the tsunami dominant frequency (in cycles/h). A realizable receiver is proposed and its performance is evaluated using actual tsunami signatures. It is demonstrated that the detection of a tsunami with an average amplitude as small as 0.7 cm is possible for theP_{D} andP_{F} as above. Simulation results using synthesized background noise are shown. Tidal effects on the receiver performance also are considered and are found negligible for a certain range of the receiver parameters, resulting in a considerable reduction of the signal processing required. 相似文献