对模式匹配算法的存储优化研究     

林南晖  张国军 《中国海洋大学学报(自然科学版)》2008,(Z1)

基于确定性有限自动机(DFA)的多模式匹配算法被广泛用于数据包深度检测系统中。它功能虽然强大,但是对内存的需求也比较大,因此很多算法提出了对它的优化方法,以减少对内存的需求量。本文通过用动态默认转移来替代DFA的failto转移,将DFA中大部分的failto转移删掉,从而达到优化DFA的目的。而且本算法易于用硬件实现,因此在对速度有要求的场合,可以通过专门的硬件来计算默认转移,这样默认转移的计算并不会对检测产生延迟,从而加快匹配速度。  相似文献   

Implementation of baroclinic terms in a three-dimensional hydrodynamic model and its application to Anzali Port, Iran     

Ali Khosh Kholgh  Peyman Badiei 《Ocean Engineering》2009,36(11):810-820

Baroclinic terms have been implemented in a three-dimensional fully hydrodynamic model developed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] modifying its momentum equations to account for density gradients and utilizing the scalar (salinity, temperature, etc.) conservation equation (SCE) and a state equation for the calculation of density. In the solution of advection-diffusion terms of the governing Navier-Stokes equations (NSE) and SCE, a symmetric splitting method was applied to ensure the long-term stability of simulations. Correction terms proposed by Ruddic et al. (1995) were applied to SCE to ensure the conservation of the scalar quantity. In the presence of baroclinic terms, the zero gradient pressure in the vertical direction in the vicinity of surface and bottom boundaries assumed by Badiei et al. [2008. A three-dimensional non-hydrostatic boundary fitted model for free surface flows. International Journal for Numerical Methods in Fluids, 56(6), 607-627] created spurious currents. This problem was solved by assuming a hydrostatic pressure variation at those boundaries. The ability of extended model was validated by comparing its results with an experimental test case. The simulation of hydrodynamic and salt intrusion at Anzali Port located at the southern coasts of Caspian Sea in Iran was carried out by the model with both barotropic and baroclinic modes. The simulated results with baroclinic mode show a better agreement with measured data as compared to the results of barotropic mode that clearly demonstrate the significance of baroclinic terms in the simulation of cyclic intrusion of salt wedge into the Port Basin.  相似文献   

The divergent environmental characteristics of permanently-open,seasonally-open and normally-closed estuaries of south-western Australia     

Benjamin M. Chuwen  Steeg D. Hoeksema  Ian C. Potter 《Estuarine, Coastal and Shelf Science》2009

This study has compared the environmental characteristics of the basins and saline lower reaches of the tributaries of eight estuaries on the south coast of Western Australia, which differ in their degree of connectivity with the ocean. Although four estuaries between 115.1° and 121.8° E along that coast remain permanently open to the ocean, the others only become open when the volume of river discharge is sufficient to breach the prominent sand bars at their mouths, which occurs annually following heavy winter and early spring rainfall in some estuaries (seasonally open) and infrequently in others (normally closed). Estuaries to the west of 118.5° E are predominantly permanently open, e.g. Oyster Harbour, or seasonally open, e.g. Broke, Irwin and Wilson inlets, whereas those further east, e.g. Wellstead Estuary and Hamersley, Culham and Stokes inlets, where annual rainfall and thus discharge are much lower, only become open after exceptionally heavy discharge. In permanently and seasonally-open estuaries, pronounced haloclines and oxyclines are present in the narrow rivers but not the wide basins where the waters are subjected to wind-driven mixing. The extent of cyclical seasonal fluctuations in environmental conditions differed markedly among the three seasonally-open estuaries and between years in one of those systems. These differences reflected variations in the relationship between the volume of fluvial discharge, which is determined by a combination of the amount of local rainfall, catchment size and extent of clearing of native vegetation, and the amount of intrusion by marine waters, which is largely controlled by the size and duration of the opening of the estuary mouth. The mean seasonal salinities in the basins of the three normally-closed estuaries increased over three years of very low rainfall to 64 in the deepest of these estuaries (Stokes Inlet) to 145 in Hamersley Inlet and to 296 in the shallowest estuary (Culham Inlet). These results demonstrate that the environmental characteristics of estuaries on the south coast of Western Australia differ markedly, even among those of the same type, e.g. seasonally-open estuaries or normally-closed estuaries.  相似文献   

Statistical approach to determine the salinized ground water flow path and hydrogeochemical features around the underground LPG cavern,Korea     

Jeongho Lee  Ji‐Hoon Kim  Hun‐Mi Kim  Ho‐Wan Chang 《水文研究》2007,21(26):3615-3626

The ground water flow path of the coastal area in the Yellow Sea, Korea, was interpreted using both the cross‐correlation analysis of hydraulic properties and the principal component analysis (PCA) of ground water chemistry. Data was obtained from observation wells in the underground liquefied petroleum gas (LPG) cavern constructed in the coastal area of Pyeongtaek. Cross‐correlation results showed that the operating pressure became more influenced on artificial factors for the variation of the groundwater level of the study area (45–66% of correlation coefficient) even though its affecting area was limited to the region with fractures or faults, and also showed that the delay time from the variation of operating pressure to the fluctuation of ground water level were relatively long periods (28–31 days). Three hydrogeochemical events (encrusted cement dissolution, host rock dissolution, and seawater intrusion), which were dominantly influenced on ground water quality, could be induced from the result of PCA. Quantitative evaluation for these events using the mixed equation with principal component scores suggest that the dissolution of encrusted cement materials was the predominant factor (39·0% of the total mixed proportion) to change the chemical composition of the seepage water during the ground water flow from the observation wells to the cavern. Integration of the statistical results also imply that ground water flow and hydrogeochemistry were predominantly affected by artificial factors such as cavern operation pressure and dissolution of encrusted cement materials, which were interdependent factors on the observation wells with high cross‐correlation coefficients and pH. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Mathematical modelling of sea water intrusion,Nauru Island     

F. Ghassemi  A. J. Jakeman  G. Jacobson 《水文研究》1990,4(3):269-281

A two-dimensional finite element model for density dependent groundwater flow was calibrated to simulate sea water intrusion in Nauru Island in the Central Pacific Ocean. Nauru Island occupies an area of 22 km² and supports a population of 8500. The island has been mined for its phosphate deposits and current reserves indicate that the mine has about eight years life remaining. The water supply of the island is about one third dependent on imported water which is also used as ballast on the phosphate ships. Imported water will not be available in the future, and a hydrogeological investigation shows that the island is underlain by a fresh water layer, less than 5 m thick. The freshwater layer overlies a thick transition zone of brackish water which in turn overlies sea water. Simulation of several management options shows that it is possible to substitute current importation of fresh water by careful extraction from the groundwater resources of the island.  相似文献   

台湾东北部黑潮次表层水入侵的季节变化规律   总被引：5，自引：1，他引：4  

赵瑞祥  刘志亮 《海洋学报》2014,36(1):20-27

台湾东北部,黑潮次表层水常年入侵东海陆架。但是黑潮次表层水入侵的季节变化规律,尚存在很多不明之处。本文基于2009至2011年间东海4个航次的CTD实测数据,研究了黑潮次表层水入侵东海过程的季节变化规律,发现:黑潮次表层水入侵在春末夏初开始加强,夏季最强,秋季开始减弱,冬季最弱。入侵的黑潮次表层水起源深度也随季节变化有所不同。另外,结果还表明黑潮次表层水入侵存在明显的短期变动。  相似文献   

长江口北支异常强盐水入侵观测与分析   总被引：2，自引：0，他引：2  

张二凤  陈沈良  刘小喜 《海洋通报》2014,33(5):491-496

长江口北支由于径流分流比很小,盐水入侵较强,特别是枯季大潮期盐水甚至倒灌进入南支,影响上海市和江苏省的水源地水质。为了进一步研究北支盐水入侵的规律及影响因素,2014年1月1-9日在北支进行了大小潮同步水文观测。本次观测到了北支异常强盐水入侵:小潮期发生强盐水入侵,且强度大于大潮期。小潮期强盐水入侵导致中下游河段被高浓度盐水控制,盐度从下游B01到中游B02几乎没有变化,且盐度的涨落潮变化几乎消失。分析认为,小潮观测期间长江入河口流量较小、河口潮差不是太小,加上强偏北风,三者的叠加是导致强盐水入侵的主要原因。  相似文献   

基于PCA和LOGIT模型的网络入侵检测方法   总被引：1，自引：0，他引：1  

李蕊 《成都信息工程学院学报》2014,29(3):261-267

针对高维度网络数据进行多类攻击行为检测的需求,提出一种基于PCA和Logit模型的网络入侵检测方法,通过PCA对网络数据降维、简化数据集和多项式Logit模型实现对不同攻击行为的识别并判别其类型。实验结果表明,方法在网络入侵识别上具有较理想的效果。  相似文献   

Research on the critical conditions for clay particle release during saline aquifer freshening process     

Xilai Zheng  Ran Chen 《中国海洋大学学报(英文版)》2014,13(4):628-636

Water sensitivity phenomenon occurs during saline aquifer freshening process in seawater intrusion area, and clay particles released in the phenomenon can damage the infiltration capacity of the aquifer. In order to find out the factors and mechanisms for clay particle release, laboratory column infiltration experiments simulating saline aquifer freshening process were designed to measure the critical conditions(critical flow velocity, critical salt concentration and critical ionic strength) and force analysis for clay particle according to DLVO electric double layer theory was employed to illustrate the mechanisms for particle release. The research results showed that critical flow velocity for clay particle release is influenced by salt concentration of injecting solution. When salt concentration of injecting solution is very high, clay particles are not released, indicating that there does not exist a critical flow velocity in this situation. As salt concentration of injecting solution decreases, particles start to be released. The critical salt concentration for clay particle release is 0.052 mol L-1 in our work, which was determined by a constant-flux experiment for stepwise displacement of high concentration Na Cl solution. The critical ionic strength for clay particle release decreases as Ca2+ molar content percentage of the mixed solution of Na Cl and Ca Cl2 increases following the first-order exponential decay equation y = 0.0391e-0.266 x + 0.0015.  相似文献   

小秦岭地区金钼多金属矿成矿特征与找矿预测     

王瑞廷  袁海潮  孟德明  王磊  马文平 《地球科学与环境学报》2014,(1):19-31

小秦岭地区是中国重要的金钼矿产基地。以构造-岩浆-成矿系统为指导,综合研究认为区内金钼多金属矿床可分为印支期—燕山期与重熔型花岗岩浆侵入活动有关的金(钼)矿床成矿系列和与深源浅成型花岗岩、碱性岩有关的钼(金钨)矿床成矿系列。金(钼)矿床类型主要包括石英脉型、构造蚀变岩型、糜棱岩型、爆破角砾岩型和复合型等,以前两者为主;钼(金钨)矿床类型主要包括斑岩型、斑岩-矽卡岩型、斑岩-爆破角砾岩型、石英-碳酸岩脉型和构造蚀变岩型等,也以前两者为主。该区三叠世以来共发生过3次岩浆侵入活动,每次都伴有不同程度的钼金矿化作用,并分别对应于不同的钼金矿化高峰期。钼的成矿作用分为印支期(210~220 Ma)和燕山期早白垩世早期(140~145Ma)、早白垩世中晚期(110~138Ma);金的成矿作用分为印支期(约220Ma)和燕山期早白垩世中晚期(约130Ma);钼、金成矿在印支期和燕山期早白垩世中晚期叠合,而在燕山期早白垩世早期分离。整体上,区内岩体与断裂构造控矿特征明显,燕山期金钼成矿作用强烈发育。该区娃娃沟—峪耳沟、峪耳沟—曹家沟、太子坪—葫芦沟—荒地沟与文公岭北坡等地区为金钼多金属矿的有利找矿靶区,并应特别重视中酸性小岩体的含矿性评价。  相似文献