共查询到18条相似文献，搜索用时 712 毫秒
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基于模糊数学和改进层次分析法的海水入侵程度评价 总被引：1，自引：1，他引：0
基于模糊数学基本思想,将海水入侵程度作为评价对象,选择Cl–、Br–、SO42–、K+、SAR等5项能敏感反映海水入侵过程的水化学指标作为评价指标,通过采用改进层次分析法计算各指标权重和运用模糊数学进行综合评价,构建海水入侵程度综合评价的数学模型。以山东省招远市作为研究区,运用评价模型对该地区海水入侵程度进行评判,评价结果较单一指标评价法更加合理准确,具有较好的实用性,可为当地海水入侵防控提供科学依据。研究表明,该模型是海水入侵程度评价的一种简易高效、科学合理的方法,可推广应用。 相似文献
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在分析和借鉴传统的水深综合理论和方法的基础上,开展水深数据的层次性分析,对水深数据进行分类、定级和聚合等处理方法研究。在满足制图综合规范的基础上,按照水深分类数据的重要性和特征性排序,重组综合方法使用顺序和结构,从而构建层次水深综合模型。该模型能够实现水深综合的流程控制,兼顾水深综合的质量要求,为进一步开展水深自动综合的实用性研究提供了理论和技术支持,具有一定实用价值。 相似文献
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浮托安装法,是相对于传统吊装法的一种新型海洋平台安装方法,具有起重能力大、作业周期短、安装费用低、适用范围广、操作安全方便等优点,解决了海上大型平台组块的安装问题。为了研究横荡护舷对浮托安装的影响,首先对海洋平台浮托安装中的护舷装置进行了介绍,然后针对某工程实例应用AQWA软件进行了数值模拟,并进行了模型验证。从时域方面对就位状态下的浮托模型进行了耦合动力分析,研究了横荡护舷参数对驳船运动和撞击力的影响规律。研究表明,横荡护舷可以有效地减小驳船运动和撞击力,其限位和缓冲作用与护舷尺寸及护舷刚度均有关。研究结果可为实际浮托安装工程提供重要的参考。 相似文献
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The loss of beach sand from berm and dune due to high waves and surge is a universal phenomenon associated with sporadic storm activities. To protect the development in a coastal hazard zone, hard structures or coastal setback have been established in many countries around the world. In this paper, the requirement of a storm beach buffer, being a lesser extent landward comparing with the coastal setback to ensure the safety of infrastructures, is numerically assessed using the SBEACH model for three categories of wave conditions in terms of storm return period, median sand grain size, berm width, and design water level. Two of the key outputs from the numerical calculations, berm retreat and bar formation offshore, are then analysed, as well as beach profile change. After having performed a series of numerical studies on selected large wave tank (LWT) test results with monochromatic waves using SBEACH, we may conclude that: (1) Berm erosion increases and submerged bar develops further offshore as the storm return period increases for beach with a specific sand grain size, or as the sand grain reduces on a beach under the action of identical wave condition; (2) Higher storm waves yield a large bar to form quicker and subsequently cause wave breaking on the bar crest, which can reduce the wave energy and limit the extent of the eroding berm; (3) A larger buffer width is required for a beach comprising small sand grain, in order to effectively absorb storm wave energy; and (4) Empirical relationships can be tentatively proposed to estimate the storm beach buffer width, from the input of wave conditions and sediment grain size. These results would benefit a beach nourishment project for shore protection or design of a recreational beach. 相似文献
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The choice of convenient basic constituents for evaluating pH stability of aqueous systems is discussed, and two useful interaction parameters are defined and related to the buffer capacity: the interaction capacity, , and the interaction intensity, ; for pH and TOTH, δ′H, H = ?βH?1, where βH is the pH buffer capacity. A method is presented for the computation of exact values of all interaction capacities and intensities through inversion of the Jacobian matrix of the system of non-linear equations describing the aqueous system. The major species of an aqueous system (H2O, H+, solid phases, gases, and the most abundant solute species) are shown to constitute a useful set of basic constituents for evaluation of approximate pH buffer capacities according to a simple rule: the major-minor species rule for zeroth order pH-TOTH interaction. The concepts of buffering and pH-statting are examined and contrasted; it is demonstrated that the buffer capacity of an aqueous system cannot be infinite: it is limited by the concentration of solutes in solution. The effect upon pH of variations in constituents other than H+ is described in terms of first order interactions via complex formation and solid formation; approximate formulas for calculation are derived. Higher order interactions are derived from combinations of first order ones. The pH stability of the ocean system is examined in terms of an aqueous phase model including ion-association reactions and a heterogeneous model incorporating CO2 in the gas phase, quartz, kaolinite, calcite, chlorite, and illite, in addition to the aqueous phase. There is an approximately three-fold enhancement of buffer capacity in the aqueous model as a consequence of ion-association. Only a few interaction pathways are of quantitative significance in establishing the buffer capacity. Results for the heterogeneous ocean model lend quantitative support to Sillén's notion of pH stability: the buffer capacity is about four hundred times greater than that of the aqueous phase model. 相似文献
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Optical buffers are critical for optical signal processing in future optical packet-switched networks. In this paper, a theoretical study as well as an experimental demonstration on a new optical buffer with large dynamical delay time is carried out based on cascaded double loop optical buffers (DLOBs). It is found that pulse distortion can be restrained by a negative optical control mode when the optical packet is in the loop. Noise analysis indicates that it is feasible to realise a large variable delay range by cascaded DLOBs. These conclusions are validated by the experiment system with 4-stage cascaded DLOBs. Both the theoretical simulations and the experimental results indicate that a large delay range of 1--9999 times the basic delay unit and a fine granularity of 25 ns can be achieved by the cascaded DLOBs. The performance of the cascaded DLOBs is suitable for the all optical networks. 相似文献
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The amount of hydrogen ion exchange on the surface of amorphous silica in seawater was measured as a function of pH at 2 and 25°C. Hydrogen ion exchange with the cations present in seawater is pH dependent and at 25°C the fraction of the surface in the cation form increases from 9% at pH 7 to 22% at pH 8. The exchange is temperature dependent and at 2°C and pH 8, 14% of the exchange sites are occupied by cations, as opposed to 22% of the exchange sites at 25°C. These results were used to calculate the buffer capacity of a model sediment consisting of pore water and amorphous silica. For a sediment of 70% porosity, pH 7.7, and 25°C, the buffer capacity of sediment plus pore water is 67 times the buffer capacity of pure seawater. 相似文献
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The present study addresses essentially to the investigation of the longitudinal vibrations of a stepped-pipe string for mining from deep-sea floors. The stepped-pipe string, consisting of four parts having different physical properties in each pipe string segment, is assumed to have two pump modules and a buffer, each of which is equipped with a vibration absorber. Moreover, the pipe string is subjected to external viscous damping because of the surrounding medium. A theoretical analysis has been made for a simplified model of the system, in which it is assumed that both the pump modules and buffer can be considered as concentrated masses, the fluid inside of the pipe string vibrates together with the string, and that the flexible pipe does not affect the vibration of the pipe string. Furthermore, absorbers are modeled as concentrated masses, each of which is attached to pump modules and the buffer by springs and dampers. Applying the method of separation of variables, exact analytical solutions for damped free and forced responses of the system subjected to heave motion of the mining ship are determined with and without absorbers, in which overdamped and underdamped modes are determined and studied separately too. It is important to note that the solutions obtained are expressed in terms of parameters characterizing the physical properties of the system under consideration. Numerical applications show that the attachment of convenient vibration absorbers causes the longitudinal displacements at the certain locations to decrease to very small values, where the vibration absorbers are adjusted to the excitation frequency. 相似文献
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The dynamic analysis of a pipe system is one of the most crucial problems for the entire mining system.A discrete element method(DEM)is proposed for the analysis of a deep-ocean mining pipe system,including the lift pipe,pump,buffer and flexible hose.By the discrete element method,the pipe is divided into some rigid elements that are linked by flexible connectors.First,two examples representing static analysis and dynamic analysis respectively are given to show that the DEM model is feasible.Then the three-dimensional DEM model is used for dynamic analysis of the mining pipe system.The dynamic motions of the entire mining pipe system under different work conditions are discussed.Some suggestions are made for the actual operation of deep-ocean mining systems. 相似文献