共查询到20条相似文献,搜索用时 46 毫秒
1.
多型航空重力仪同机测试及其数据分析 总被引:3,自引:0,他引:3
介绍了运8飞机加装4型5套航空重力仪开展同机测试的整体情况,对5套重力仪所获取的重复线和测网成果数据进行了对比分析。试验结果表明,俄罗斯GT-1A航空重力仪具有最佳的综合性能技术指标,平差前测量精度为±2.45mGal;美国TAGS航空重力仪为其次,平差前测量精度为±3.9mGal;SII型船载海空重力仪可改造升级为航空重力仪,并具有与TAGS同等的综合性能技术指标;国内自主研发的SGA-WZ01捷联航空重力仪具有最佳的重复线测量精度,测网精度接近于GT-1A航空重力仪水平,平差前测量精度为±2.96mGal,另一款自主研制的GDP-1重力仪首次成功实现了航空重力测量功能,平差前测量精度为±4.52mGal。 相似文献
2.
3.
4.
5.
在海上复杂的环境下进行重力测量,重力仪及技术人员的操作难免会出现各种各样的问题,导致测量的成果精度降低,甚至不符合规范要求。目前检查海洋重力测量成果质量的主要方法是内符合法,主要采用主测线、检测线交叉点的差值,或重复测线相邻点的差值来评估测量成果的质量。介绍了内符合法存在的弊端,比较了DTU重力数据与重力仪实测数据的精度,叙述了基于DTU重力数据检查海洋重力测量成果较大系统差的可行性,以模型数据为外符合数据源来检查实测成果的质量,作为内符合法的补充,是十分必要的。 相似文献
6.
7.
8.
重力资料的质量高低及其应用范围在很大程度上取决于所使用的重力测量仪器设备。目前广泛使用的重力仪大都为相对重力仪,自30年代第一台海洋重力仪诞生以来,已有70a历史,特别是近20a来随着金属材料技术、电子技术、传感技术和计算机技术的高速发展,对重力仪的集成化、数字化、自动化方面有了重大的改进和发展,使它在轻型化、自动化方面有了很大的发展,更容易操作,更快速地取得测量资料。 本文根据最新的文献资料和对当前国际市场上海洋重力仪的发展情况进行介绍,并且介绍LA-COSTE&ROMBERG公司生产的航空-… 相似文献
9.
S型海洋重力仪是目前海洋重力测量中较为常用的一种仪器,其产品性能也逐步得到提高。介绍了进行全自动化控制升级后,最新引进的SⅡ型海洋重力仪使用中出现的稳定平台颤动故障现象及排除办法。 相似文献
10.
对KSS31M型海洋重力仪阻尼延迟时间进行了修正,分别用修正前的110s阻尼延迟时间和修正后的60s阻尼延迟时间对南海某工区的重力数据进行了校正和处理,结果表明:用110s阻尼延迟时间对数据进行校正后得到的测量精度在平差前为1.6mGal,平差后为1.0mGal,用60s阻尼延迟时间对数据进行校正后得到的测量精度在平差前为1.4mGal,平差后为0.8mGal,平差前和平差后的测量精度均提高了0.2mGal。此结果证明了利用船只机动转向确定海洋重力仪在测量过程中的实际阻尼延迟时间方法的必要性和实际应用价值。 相似文献
11.
12.
港口内靠码头系泊船运动的计算 总被引:11,自引:1,他引:11
本文以英国南海岸处Shoreham港内系泊船为例,研究了港口内靠码头系泊船运动的数值计算问题。该船的实船实验和模型实验已经完成,为验证本文计算结果提供了依据。运动方程在时域内求解。在计算船体脉冲响应函数时,引入了船体阻尼系数在频率很低时的渐近表达式和一迭代算法。分析了港内共振波浪和其对船体的作用力。讨论了靠码头系泊船运动的非线性特征。计算结果与实验结果符合很好。 相似文献
13.
提出一种基于序贯预测误差方法(SPE)的多层神经网络(MNN)的学习算法。经模拟计算,它比传统的基于最陡下降方法的误差反传(SDBEP)算法具有更好的收敛性能。并对这两种算法进行了模拟计算的比较. 相似文献
14.
An elliptic jet and a square jet flowing into a counterflow with different jet-to-current velocity ratios are investigated by using realizable k–ε model. Some computed mean velocity and scalar features agree reasonably well with experimental measurements, and more features are obtained by analyzing the computed results. After fluid issues from a nozzle, it entrains ambient fluid, and its velocity and concentration on the centerline decay with the distance downstream from the potential core (l0). The decay ratio increases with the decreasing jet-to-current velocity ratio α. For an elliptic jet, the evolution of the excess velocity half-width b and the concentration half-width bc merely remains constant near the jet exit on major-axis plane while they increase linearly on the minor-axis plane. However, the half-widths on the major-axis and minor-axis plane become proportional to the axial distance downstream after equaling each other. For a square jet, b and bc increase linearly with the distance downstream from the jet exit, but the spread ratio is larger on the middle plane than that on the diagonal plane before they equal each other. The radial extent of the dividing streamline rs or the mixing boundary rsc increases linearly downstream, and decreases exponentially after reaching a peak at xb. The ratio on the minor-axis plane is larger than that on the major-axis plane for an elliptic jet. The characteristics are the same for the square jet. b, bc, rs, and rsc on two corresponding planes become equal to each other more rapidly for the square jet than for the elliptic jet, because the sharp corner of the square nozzle induces secondary structures that are more intense. The distributions of the excess axial velocity and scalar concentration exhibit self-similarity for either the elliptic jet or square jet in the region of l0 < x < xb. On the cross section, four counter-rotating pairs of vortices, which enhance the entrainment between the jet and counterflow, form at the four corners of the square jet or at the two ends of the major-axis plane of the elliptic jet. The recirculation pattern formed by these axial vortices is more complex for the square jet than that for the elliptic jet. The turbulent kinetic energy k have large value in the region near the jet exit and stagnation point. The maximum value of k for the square jet is larger than that of the elliptic jet near the jet exit. This results in the square jet mixing more strongly than the elliptic jet. 相似文献
15.
This paper deals with the study of moisture budget of the typhoon No. 7507. The results show that the mass convergence produced by divergent wind has made the maximum contribution to precipitation, especially at the lower level, accounting for about 70% of the total precipitation, and that the advection term of water vapor is very small. The vertical flux term is to transport water vapor from the lower level to the middle and upper levels, resulting in the increase of water vapor accumulation at these levels. Evaporation term also plays an important role in precipitation, accounting for about 13% of the total precipitation and 23% of the horizontal moisture convergence. The moisture of the typhoon comes mainly from its southern boundary and the secondary inflow of moisture is from its western or eastern boundary. All the inflow layers of these three boundaries are very deep, reaching up to 300 hPa, while the strongest inflow occurs below 700 hPa. In the northern boundary of the typhoon, we obtained that 相似文献
16.
中国隆头鱼之一新属新种——尖尾新丝隆头鱼 总被引:1,自引:0,他引:1
在过去几年的西沙群岛鱼类区系调查中,我们曾在西沙群岛的东岛和永兴岛附近水域,先后三次采到5尾前所未曾见过的隆头鱼类标本,经过比较研究后,认为是一新属、新种,定名为“尖尾新丝隆头鱼”,(Neocirrhilabrus oxyurus gen. et sp. nov.)现描述如下: 相似文献
17.
A Time-Domain Coupled Model for Nonlinear Wave Forces on A Fixed Box-Shaped Ship in A Harbor 总被引:2,自引:1,他引:1
A 2-D time-domain numerical coupled model is developed to obtain an efficient method for nonlinear wave forces on a fixed box-shaped ship in a harbor.The domain is divided into an inner domain and an outer domain.The inner domain is the area beneath the ship and the flow is described by the simplified Euler equations.The other area is the outer domain and the flow is defined by the higher-order Boussinesq equations in order to consider the nonlinearity of the wave motions.Along the interface boundaries between the inner domain and the outer domain,the volume flux is assumed to be continuous and the wave pressures are equal.Relevant physical experiment is conducted to validate the present model.It is shown that the numerical results agree with the experimental data.Compared with the coupled model with the flow in the inner domain governed by the Laplace equation,the present coupled model is more efficient and its solution procedure is more simple,which is particularly useful for the study on the effect of the nonlinear wave forces on a fixed box-shaped ship in a large harbor. 相似文献
18.
王荣良 《中国海洋大学学报(自然科学版)》1988,(1)
本文对J.Maynard Smith提出的物种竞争模式: x=x(a-bx-cy-kxy) y=y(e-fx-gy-lxy)作了定性分析,并给出两物种共存或其中任一物种死亡,而另一物种趋于确定值的条件。 相似文献
19.
Field measurement of waves and wave pressure in a given harbour were carried out in the years 1973 and 1977 and then the statistical analysis was made. Based on this analysis and the linear wave theory some problems concerning the total pressure spectrum and the total pressure crest value and trough value are discussed, and the method of calculating these quantities is given. 相似文献
20.
An edge wave is a kind of surface gravity wave basically travelling along a shoaling beach. Based on the periodic assumption in the longshore direction, a second order ordinary differential equation is obtained for numerical simulation of the cross-shore surface elevation. Given parameters at the shoreline, a cross-shore elevation profile is obtained through integration with fourth-order Runge-Kutta technique. For a compound slope, a longshore wavenumber is obtained by following a geometrical approach and solving a transcendental equation with an asymptotic method. Numerical results on uniform and compound sloping beaches with different wave periods, slope angles, modes and turning point positions are presented. Some special scenarios, which cannot be predicted by analytical models are also discussed. 相似文献