共查询到20条相似文献，搜索用时 31 毫秒
1.
The relationships between sea surface roughness z 0 and wind-wave parameters are analyzed,and spurious self-correlations are found in all of the parameterization schemes.Sea surface drag coefficient C D is fitted by four wind-wave parameters that are wave age,wave steepness,windsea Reynolds number R B and R H ,and the analyzed data are divided into laboratory,field and combined data sets respectively.Comparison and analysis of dependence of C D on wind-wave parameters show that R B can fit the C D most appropriately.Wave age and wave steepness are not suitable to fit C D with a narrow range data set.When the value of wave age has a board range,R H is not suitable to fit C D either.Three relationships between C D and R B are integrated into the bulk algorithm COARE to calculate the observational friction velocity,and the results show that the relationship between C D and R B which is fitted with field data set can describe the momentum transfer in the open ocean,under low-moderate wind speed condition,most appropriately. 相似文献
2.
Peter R. Payne 《Ocean Engineering》1981,8(5):541-545
The skin friction of a two-dimensional planing flat plate is made up of two opposing components; a drag force from the flow aft of the stagnation line and an opposing thrust force from the jet flow. This paper is concerned only with the drag term and the wake velocity defect which it causes in the water behind the transom.It is concluded that the skin friction is less than would be expected from a flat plate at ambient static pressure (Dfo say) and is approximately equal to Dfo (1 − CR), where CR is the normal force coefficient based on wetted area. The wake velocity decrement due to this drag is found to be significant, particularly for surface piercing propellers. 相似文献
3.
人放天养的中华绒螯蟹(Eriocheir sinensis)质量好、个体大、耐运输、肉质鲜美,是优质高档蟹的代表,但产量严重不足。建立一套湖泊中华绒螯蟹自然生产潜力估算的模型来估算湖泊中华绒螯蟹自然生产潜力,确定放养量,以达到湖泊中华绒螯蟹稳产已迫在眉睫。本文根据近20年来作者对湖泊中华绒螯蟹放养的经验,结合灰估理论,提出蟹自然生产潜力:W=[B1K1C1/R1+B2K2C2/R2]·(B1+B2)2/B12+B2和蟹种放养量:W0=P0[B1K1C1/R1+B2K2C2/R2]·U/P估算模型,并与生产实践进行求证。其结果与生产实践存在较好的一致性。其估算结果可作为指导湖泊中华绒螯蟹生产的依据。 相似文献
4.
Li Luping 《海洋学报(英文版)》1997,16(1):45-56
In this paper, it is held that the universal relationships of wave growth in fetch-limited conditions , i. e.,(f|~) p=A(x|~)-Band (m|~)0= C(x|~) Dshould satisfy the Toba 3/2 power law and the wave energy balance equation. In the ideal generation situation, theoretically it can be derived that the ideal fetch-limited wave growth relationship should have D=3B and D B =1, (i.e., B = 0.25, D = 0.75 ) and A3C=2. 1×l(T4C~(1/2)_d , where Cd is the drag coefficient. The 3/2 power law, the wave energy balance equation and the decrease of wave steepness with increasing fetch have became three requirements which should be satisfied by fetch-limited wave growth algorithms. A semi-empirical and semi-theoretical model for fetch-limited wave growth is presented. In the application to the slanting wind situation an un(?)ersal relationship of dimensionless wave energy vs dimensionless peak frequency is presented and the comparisons show that the model is in good agreement with observations. 相似文献
5.
Examination of wind-wave interaction source term in WAVEWATCH III with tropical cyclone wind forcing
Results of drag coefficient(CD) from field observations and laboratory wave tank experiments indicate that the operational wave model can overestimate wind energy input under high wind conditions. The wind-wave interaction source term in WAVEWATCH Ⅲ has been modified to examine its behavior with tropical cyclone wind forcing. Using high resolution wind input,numerical experiments under idealized wind field and tropical cyclone Bonnie(1998) were designed to evaluate performance of the modified models. Both experiments indicate that the modified models with reduced CD significantly decrease wind energy input into the wave model and then simulate lower significant wave height(SWH) than the original model. However,the effects on spatial distribution of SWH,mean wavelength,mean wave direction,and directional wave spectra are insignificant. Due to the reduced wind energy input,the idealized experiment shows that the modified models simulate lower SWH than the original model in all four quadrants. The decrease in the front quadrants is significantly larger than that in the rear quadrants;it is larger under higher winds than lower winds. The realistic experiment on tropical cyclone Bonnie shows that the modified model with the various downward trends of CD in high winds creates a simulation that agrees best with scanning radar altimeter observations. 相似文献
6.
利用第三代海浪数值模式(SWAN)系统研究了黄海海浪有效波高的天气时间尺度变化的时空分布特征和相关动力学过程。结果表明黄海海浪有效波高的天气变化强度(S_W)具有显著的时间变化特征和空间分布特征。其多年平均值在黄海的中东部存在由南向北延伸的高值区,同时向两侧近海区域逐渐减小。S_W在冬季最大,夏季最小。从11月到翌年5月,S_W月气候态平均值的空间分布与其年平均值的空间分布类似;从6月到同年10月,S_W的月气候态平均值在黄海与东海的分界处存在较强的由黄海到东海的空间梯度。进一步分析表明黄海海域的S_W以风浪占主,涌浪的贡献远小于风浪贡献。数值实验表明,黄海海浪有效波高的天气时间尺度变化主要是由大于天气变化周期的海面风强迫通过四波非线性相互作用产生的。 相似文献
7.
Experimental investigations on perforated hollow piles in two rows were conducted in a two dimensional wave flume. The influence of water depth, incident wave steepness, clear spacing between the piles and the spacing of pile rows on transmission coefficient have been studied. The effect of staggering of piles in rows is investigated. The results are also compared with the results of experiments on piles without perforations. The investigations have revealed that perforated piles attenuate more wave energy than non-perforated piles. The transmission coefficient Kt decreases as the wave steepness increases for both non-perforated and perforated piles. For non-perforated piles as relative clear spacing between the piles (b/D) decreases, for waves of higher steepness, Kt decreases while for perforated piles as b/D decreases, Kt is decreasing for all the steepness considered. As the relative clear spacing between the pile rows (B/D) increases Kt initially decreases till B/D is around one and later it starts increasing for both non-perforated and perforated piles. Staggering of piles has little effect on Kt. It is also found that water depth has insignificant influence on transmission coefficient at higher steepness for both perforated and non-perforated piles. Wave period alone does not directly influence transmission coefficient Kt. 相似文献
8.
The previous studies by the MASNUM research team have shown the effectiveness of the wave-induced mixing (Bv) in improving the simulation of upper-ocean thermal structure. The mechanisms of Bv are further investigated by incorporating different Bv products into the MASNUM wave-circulation coupled model. First, experiments were designed to explore the effects of Bv, which contain the contributions at different wave lengths (l). The results of three experiments, the non-Bv case, the short-wave case (l <300 m), and the long-wave case (l >300 m) are compared, and it is found that the long waves are the most important component for Bv to generate mixing in the upper ocean. As the swell plays dominant role in mixing, the parameterization of Bv into wind may be not a proper way. Second, Bv effects at different time-scales, including daily and monthly, were examined. The results show that the monthly averaged Bv has larger impact than the daily averaged Bv, especially in summer. 相似文献
9.
关于海水中铀(Ⅵ)与水合氧化钛的作用、国内外已有许多报导,内容包括水合氧化钛制备方法的不同对交换铀量的影响,水合氧化钛和海水中铀的基本物理—化学性质的研究及它们在反应过程中物理—化学性质变化规律的研究,海水中铀与水合氧化钛作用机理的研究等等。但对这一反应的动力学研究文献上报导极少,除了在本研究Ⅰ、Ⅱ和Ⅲ中报导的反应机理的研究[1,2]证明反应过程的速率由液膜扩散所控制之外,关于这一离子交换过程的反应级数和活化能的研究却至今未见有文献报导。 相似文献
10.
Near-surface upward irradiances within each band of the MSS (multi spectral scanner) of LANDSAT, were computed from observed spectral upward irradiances measured just beneath the sea surface. Computation of these irradiances is a useful first step in the analysis of remotely-sensed radiance because the data are not affected by the effects of the atmosphere and sea surface. The computed irradianceE in LANDSAT bands 4, 5 and 6 was normalized by forming ratios,i.e., R
45=E4/E5, R46=E4/E6, andR
56=E5/E6, and then the relationship between these ratios and chlorophylla plus phaeopigment concentration (C) observed simultaneously at 59 stations was examined by linear regression analysis. The observedC ranged over nearly three orders of magnitude, and there is a close to linear relationship between log10-R
45 and log10
C. This suggests that it may be possible to evaluateC from LANDSAT data, if an appropriate atmospheric correction is made. The relationship between suspended solids determined at 35 stations and the same ratios of upward irradiance is also presented and discussed. 相似文献
11.
Peter R. Payne 《Ocean Engineering》1981,8(5):489-496
The skin friction of a two-dimensional planing flat plate is made up of two opposing components; a drag force from the flow aft of the stagnation line and an opposing thrust force from the jet flow. This paper is concerned only with the drag term and the wake velocity defect which it causes in the water behind the transom.It is concluded that the skin friction is less than would be expected from a flat plate at ambient static pressure (Dfo say) and is approximately equal to Dfo (1 ? CR), where CR is the normal force coefficient based on wetted area. The wake velocity decrement due to this drag is found to be significant, particularly for surface piercing propellers. 相似文献
12.
Dependence of Whitecap Coverage on Wind and Wind-Wave Properties 总被引：13，自引：0，他引：13
13.
AbstractVacuum preloading with plastic vertical drains has been applied widely to accelerating consolidation of dredger fills. As a result of nonlinear variations in permeability and compression during the process of dredger fill consolidation, an axisymmetric consolidation method for dredger fill treatment using PVD with vacuum is proposed with varied Ru. The effects of Cc/Ck and the loading ratio on the proposed method are discussed. It is found that the difference between the traditional method and proposed method is obvious in the case of large loading ratio (such as dredger fill treated with vacuum preloading). The degree of consolidation in the early phase of consolidation obtained using the proposed method was less than that obtained using the traditional method and the degree of consolidation in the later phase of consolidation obtained using the modified expression was larger than that obtained using the traditional method, as Cc/Ck?<?1. However, opposite trends were observed when Cc/Ck?>?1, the proposed method was closer to the actual situation. The applicability of the proposed method was verified by laboratory and field tests. For the consolidation of dredger fill with high water content, we recommend the adoption of the proposed method for calculating the degree of consolidation. 相似文献
14.
An improved gas chromatographic system was constructed to analyze oceanic dissolved N2, Ar and O2 with a higher accuracy and shorter analytical time. To obtain a higher accuracy of N2, Ar and O2 measurements, the following was added to the system: (I) an air trapping system; (II) a N2–CO2 trapping system after the operation of the air trapping system; (III) an active carbon column system for separating N2 and CO2 completely and (IV) the introduction of automatic valves controlling most of the system. Compared to previous studies, the precision of the measurements of N2, Ar and O2 concentrations was higher at 0.04%, 0.05% and 0.02%, respectively, and our analytical time was shorter at 600 s. Using the improved analytical technique, concentrations of N2 (CN2, 561.69–611.81 μmol/kg) and Ar (CAr, 15.126–16.238 μmol/kg), saturation states of N2 (ΔN2, − 5.1–0.9%) and Ar (ΔAr, − 7.0 to − 1.1%) from 0 m to 3000 m depth in the western North Pacific were observed during March 2005. Based on these data, we propose a new concept for estimating the amount of bubble injection (B). The total error in calculating B was estimated to be about 20%. We estimated B from 12 to 43 μmol/kg in this region using the observational values of N2 and Ar. As each water mass had a significantly different value of B even with an error of 20%, it is possible to use it as an index of sea surface state for when each water mass is produced in the sea surface mixed layer. Moreover, based on our values of B, we estimated preformed dissolved oxygen (DO) (CpreDO, 309–332 μmol/kg) and the saturation state of CpreDO (ΔpreDO, − 7.0 to − 1.2%) in this region. Thus, the difference between CpreDO and DO content in the ocean interior may be a more useful index for biogenic organic decomposition in the ocean field compared to Apparent Oxygen Utilization (AOU). Until now, the estimation of oceanic uptake of anthropogenic CO2 has used AOU as a major parameter. Therefore, it may be necessary to re-evaluate the oceanic uptake of anthropogenic CO2 based on our new concept of B. 相似文献
15.
马氏珠母贝两个与生长性状相关QTL 的验证 总被引：2，自引：0，他引：2
利用2个马氏珠母贝群体对遗传连锁图谱已经定位的,与马氏珠母贝生长性状相关的数量性状位点(Quantitative trait locus,QTL)中的两个进行验证。结果显示:m59标记在2个群体中与壳高、壳长、壳宽和总重具有显著的相关性(P0.05),其GT基因型的个体壳高、壳长、壳宽和总重均显著高于GG基因型的个体;154165标记在湛江群体中与壳高具有显著相关性(P0.05),而在深圳群体中与壳宽具有显著相关性(P0.05);表明QTL标记m59在2个群体中是共享QTL,而154165标记在群体中是特异QTL。基于这两个QTL在这2个群体中分别构建二倍型,发现在湛江群体中二倍型C_1(AAGT)和深圳群体中D_1(AGGT)型和D_2(AAGT)型对马氏珠母贝生长最为有利,可作为优先的基因型组合。 相似文献
16.
The characteristics of swells within the East China Sea have been reported by Tao et al.(2017), while the question of where the swells come from remains unanswered. By using the wave model WAVEWATCH III and the swell tracking method proposed by Hanson(2001), the spatial sources of the swells are investigated during four typical typhoon scenarios, which usually affect the wave environment in the East China Sea, including the Recurving type,the Northward type, the Westward type(striking the East China Sea) and the Westward type(over the South China Sea). The numerical results show that parts of the swells are from the North West Pacific with a long-distance travelling. The moving paths of the swells are affected by the typhoon tracks, which result in various fetches. The Westward type(over the South China Sea) makes one peak in the evolution process. The landing process of the Westward type(striking the East China Sea) could result in swells with low energy. The swell energy depends on swell propagation distance, existence time and wind intensity of generation fetch. The consistent fetch and forceful wind intensity make swell carry more energy. 相似文献
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18.
The prediction of ship stability during the early stages of the design process is very important from the point of a vessel's safety. Hence, in this study, a formula is presented to estimate cross curves of fishing vessels to predict initial stability at the preliminary design stage. For this purpose, 175 fishing vessel forms have been generated from Doust trawler hull series. The predictive technique is established by regression analysis of systematically varied fishing vessel series data. The mathematical model is constructed as a function of main design parameters such as length to beam ratio LWL/BWL, beam to draft ratio BWL/T, moulded depth to draft ratio D/T and block coefficient CB. This prediction is also used to determine the effect of specific hull form parameters and load conditions on the stability of the fishing vessel. Some basic considerations on how the proposed method can be applied to a new fishing vessel are presented. 相似文献
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20.
The experimental results have so far shown that when a wave breaks on a vertical wall with an almost vertical front face at the instant of impact that is called perfect breaking or perfect impact, the greatest impact forces are produced on the wall. Therefore, the configuration of breaking waves is important in the design considerations of coastal structures. The present study is concerned with determining the geometrical properties of oscillatory waves that break perfectly on the vertical wall of composite-type breakwaters. The laboratory tests for perfect breaking waves on composite breakwaters are conducted with base slopes of 1/2, 1/4 and 1/6, and with berm widths of 0.00, 0.10, 0.20, 0.30 and 0.40 m. The shape and the dimensions of waves at the instant of perfect breaking on the wall are determined using a video camera. The experimental results for the geometrical properties of the breakers are presented non-dimensionally. Within the range of present experimental conditions, it is found that the dimensionless breaker crest height, hb/dw, and dimensionless breaker height, Hb/dw, decrease; and, dimensionless breaker depth, dw/H0, increases with increasing relative berm width, B/D. The breaker height index, Hb/H0, is almost unaffected by B/D. The deep-water wave steepness and the base slope of the breakwater do not seem to influence the geometrical properties of the breakers at wall systematically. 相似文献