共查询到20条相似文献,搜索用时 140 毫秒
1.
船舶设计制造是一个众多单位利用不同工具来同时实现的系统工程,在这个过程中,必然产生大量不同结构不同介质的数据.为了解决数据交换问题,该文利用XML技术,提出了一个基于STEP标准的船舶产品模型的标准化应用思路. 相似文献
2.
目前西班牙南部阿尔梅里亚省的泰伯那斯地区的陆地和沙漠高原正逐渐成为世界上最大的太阳能利用中心。那里有两个不同的太阳能塔楼工厂,拥有一个很大的太阳能吸收场地,利用一万五千多平方米的定日镜, 相似文献
3.
随着应用的扩大,一个应用程序可能需要从一个操作系统下移植到另外的操作系统下运行,为此,本文利用面向对象的方法设计了一个操作系统封装层。当应用程序在不同的操作系统下移植时,无须对其进行修改,只需改变封装层接口内部的几个参数即可,这样增加了应用程序的可移植性。利用面向对象的方法,该封装层对上层应用提供一个统一的操作系统接口,在接口内部通过宏定义的方法来定义实际运行的操作系统。实际运行表明,两种方法的结合具有比较好的效果。 相似文献
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
基于STBC的多发射天线选择的传输性能研究 总被引:1,自引:0,他引:1
对于多发单收的天线系统(MISO),在已知信道状态信息(CSI)和等发射天线功率分配的情况下,利用反馈的CSI,对采用正交空时组码(STBC)的N选择n(N≥n,即n-NTx)的MISO系统进行研究。给出了求解选择性信道的序系数,推导了n-NTx系统的边缘概率密度函数(pdf)。在独立的平坦瑞利衰落信道中,完整地导出了n-NTx系统关于BPSK/QPSK调制的比特误码率(BER)性能界的理论表达式。为了与没有天线选择(即满复杂度)的系统进行性能比较,给出了BER的理论分析值和蒙特卡洛仿真结果,它们的结果均表明多天线选择系统能极大地提高系统的性能。 相似文献
14.
邱艳华 《交通部上海船舶运输科学研究所学报》2008,31(1):57-60
通过对上海市不同区域、不同性质的3个工业区的污水收集处理系统的实际调查,对同类工业区污水收集处理系统评估中运用的一些方法和需要注意的问题进行了探讨。提出应全面掌握工业区相关规划和污水收集处理系统实施情况,评估重点应根据不同工业区的建设情况和污水收集处理系统实施情况而有所不同,最后针对调查结果提出优化建议和改进方案。 相似文献
15.
《船舶水污染物排放控制标准》(GB3552-2018)(以下简称新《排放标准》)于2018年7月1日正式实施,对客运船舶的生活污水排放接收做了严格的规定。通过对新《排放标准》的研究和对相关单位部门的调研,发现辖区客运船舶生活污水处置存在新《排放标准》执行难、生活污水排放监管难、岸上接收处置难等问题和难点。建议地方政府等部门加强政策宣传、出台激励政策、加快码头生活污水接收设施建设、加强联合监管等措施,减少客运船舶生活污水非法排放,从而保护海洋环境。 相似文献
16.
《船舶与海洋工程学报》2016,(4)
The authors previously introduced a semi-empirical formula that enabled fast estimation of the added resistance of ships in head waves, and in this study the formula is further refined for easy use in engineering applications. It includes an alternative ship draft correction coefficient, which better accounts for the wave pressure decay with ship's draft. In addition, it only uses the speed and main characteristics of the ship and wave environment as input, and has been simplified to the extent that it can be readily processed using a pocket calculator. Extensive validations are conducted for different ship types at low to moderate speeds in various typical irregular sea conditions, and encouraging results are obtained. This relevant and topical research lies within the framework of the recent IMO MEPC.232(65)(2013) EEDI guidelines for estimating the minimum powering of ships in adverse weather conditions, which specify for the use of simple methods in current Level 2 assessment within engineering applications. 相似文献
17.
海洋工程桩-桶基础设计及颗粒流数值模拟 总被引:3,自引:0,他引:3
提出了新型的桩 桶基础的设计概念,并进行了上拔荷载作用下的数值模拟试验。桩 桶基础是桩和桶的结合,结合了桩基础、桶基础在海洋工程中体现的各自优势。通过颗粒流理论和PFC2D程序,应用细观力学的方法对上拔荷载作用下的桩 桶基础进行了模拟试验,研究了桩 桶基础在客观存在上拔荷载过程中土颗粒的分布及变化、土颗粒的位移与变化,基础的上拔位移与时步关系,土体受上拔荷载影响区域的范围及其变化。根据土颗粒的分布、颗粒的结构、颗粒的位移及其变化,基础位移与时步曲线的凸、凹变化表明了土体的稳定与破坏,判定了基础上拔时的土中滑动破坏面为锥体,综合确定了极限上拔承载力,对基础受荷过程中土颗粒细观结构变化,针对颗粒流仿真试样的细观力学特征与宏观力学响应进行了初步研究并揭示了一些规律。 相似文献
18.
《船舶与海洋工程学报》2017,(1)
The solution of water wave scattering problem involving small deformation on a porous bed in a channel, where the upper surface is bounded above by an infinitely extent rigid horizontal surface, is studied here within the framework of linearized water wave theory. In such a situation, there exists only one mode of waves propagating on the porous surface. A simplified perturbation analysis, involving a small parameter ?(7)(28)1(8), which measures the smallness of the deformation, is employed to reduce the governing Boundary Value Problem(BVP) to a simpler BVP for the first-order correction of the potential function. The first-order potential function and, hence, the first-order reflection and transmission coefficients are obtained by the method based on Fourier transform technique as well as Green's integral theorem with the introduction of appropriate Green's function. Two special examples of bottom deformation: the exponentially damped deformation and the sinusoidal ripple bed, are considered to validate the results. For the particular example of a patch of sinusoidal ripples, the resonant interaction between the bed and the upper surface of the fluid is attained in the neighborhood of a singularity, when the ripples wavenumbers of the bottom deformation become approximately twice the components of the incident field wavenumber along the positive x-direction. Also, the main advantage of the present study is that the results for the values of reflection and transmission coefficients are found to satisfy the energy-balance relation almost accurately. 相似文献
19.
This work analyses the influence of three types of modal matrices on the prediction of vibration response (virtual sensing), at unmeasured degree of freedoms (DOFs), on a catamaran’s main deck: (1) uncorrelated finite element (FE), (2) correlated FE and (3) experimental modal matrices.A multi-objective genetic algorithm (MOGA) framework was developed to handle the optimization and prediction processes. This framework introduces a new metric called Time–Frequency-Error Response Assurance Criteria (TFERAC) to assess the prediction quality. This metric also allows estimating the best set of modal acceleration vectors, which is a critical step in the virtual sensing process.As a case study, only 06 accelerometers and 13 vibration modes (within each modal matrix) were used in the virtual sensing. The MOGA framework’s performance was evaluated using a variance analysis test (ANOVA) between measured and predicted response signals.Results showed that: (1) any one of the modal matrices could be used successfully for virtual sensing on the main deck, that is, there is no need to use correlated FE or experimental modal matrices; (2) the newly proposed metric TFERAC leads to smaller errors in the prediction of both vibration time series and vibration spectra;(3) it is possible to perform a virtual sensing on a ship’s main deck using a limited number of sensors and a numerical modal matrix without being correlated with experimental data. 相似文献
20.
J.M. Huthnance 《Journal of Marine Systems》1997,12(1-4)
The EC MAST project PROFILE (Processes in Regions of Freshwater Influence, ROFIs) aims to develop process understanding and tested numerical models for ROFIs. This includes the role of physical processes controlling water-property distributions, suspended sediments controlling the availability of light, nutrients and phytoplankton growth. The project comprises: (1) construction of a 3D nearshore model, with high resolution (1 h and one km approx.) and a framework coupling modules for hydrodynamics (tides, effects of winds and waves, currents, temperature, salinity, turbulence and diffusivity), sediments, plankton, nutrients and oxygen, (2) investigation of methods to include ROFI model detail in coarser shelf-wide models, (3) specific tests of model components against measurements, (4) tests of model calculations against measurements in contrasted ROFIs, (5) systematic observations suitable for these model tests (time-series over a seasonal cycle for dynamics and intermittency, good vertical resolution and spatial surveys) of the contrasted Rhine, Clyde and Thermaikos Bay ROFIs, complementing earlier measurements in the ROFI areas of the Rhine, German Bight and Po, (6) interpretation and comparison of the contrasted ROFIs' behaviour, (7) a defined set of observations, model code and output suitable for subsequent integration and promulgation as test data and a nearshore model for wider use. 相似文献