当无人机爱上航母

舰载机在航母平台甲板上起飞着陆,除了依靠精密的导航和助飞、拦阻索设施外,对飞行员起降技术要求较高。美军条例规定,一名海军航空兵飞行员,每次升空最多10小时。这意味着舰载机的持续作战时间有了一个上限。然而,在航母上使用无人机后,情况则会有很大不同。     

工作服:航母舰上的职业标志

现代航空母舰,酷似一座硕大无比的浮动海上机场。第二次世界大战以来。航空母舰一直称雄大海,因为舰上装配有种类齐全的舰载机,包括直升机、战斗机、攻击机、预警机、电子战机、反潜机、加油机等。为此,舰上常配有数千名船员。例如。美国“尼米兹”号航空母舰舰上足有5984名舰员。全舰仅机库甲板以上就有9层,甲板以下除双层底外还分8层,大小住舱几百个,床铺6410个。人们会     

谁最倒霉—历史上最倒霉的10艘舰船

瑞典海军觉得有必要建造一艘巨型战舰，它有两层甲板，配备64门大炮。这艘超级战舰取名为“瓦萨号”于1628年8月2日第一次试航。当它缓缓驶离斯德哥尔摩港时，舰上全体水兵向前来观看的瑞典国王致敬。这时，一阵狂风吹来，舰身立刻倾斜。接着“瓦萨号”又慢慢恢复平衡，但随即再一次朝右舷倾斜。     

“美利坚”号两栖攻击舰

美国海军及陆战队每每对外用兵，大有以航母挂帅的航母打击群（CSG），小则有以大型两栖攻击舰领衔的远征打击群（ESG）。从这个意义上说，航母和两栖攻击舰俨然成为美军纵横大洋的“中坚”。     

海战先锋——航母型登陆舰

现代登陆作战中,直升机的重要性已被证实,新造的登陆舰能装载为数不少的直升机,以发挥直升机和登陆艇的立体作战能力。这类登陆舰的船型类似航空母舰,拥有全通式飞行甲板,被称作航母型登陆舰,它们已成为沿海作战的最重要的舰种。世界上已有和正在建造的航母型登陆舰有:美海军5艘塔拉瓦级大型多用途两栖攻击舰和8艘黄蜂级多用途两栖攻击舰,英海军大洋号两栖突击直升机母舰,法海军正在建造的2艘西北风级两栖攻击舰,意大利海军3艘圣乔治奥级船坞两栖运输舰,以及日本海上自卫队3艘大隅级运输舰。     

今日军情

美海军双航母编队在南海举行联合演习 8月17日,美国海军核动力航母“卡尔·义森”号编队与常规动力航母“星座”号编队在南海举行联合演习。美海军参演舰艇共15艘,分别上载两支航母编队的第11舰载机联队和第2舰载机联队共159架舰载机同时参演。演习的核心内容是研究如何抵御低空来袭的超音速反舰导弹,重点演练对付俄制“马斯基特”反舰导弹科目。     

西连岛与连云港港区风基本特征研究

本文针对连云港港区特殊的地理地形和西连岛的地理位置关系,研究了两地之间风的基本特征和相互关系,发现了港区内风受地形影响显著,无论风向,或者风速在各方位上分布和季节上分布都比西连岛风复杂,不均匀;两站风速之间对应关系不明显,而风向存在明显的对应关系;港区风在地形作用下产生非线性效应,其结果跟西连岛风向之间存在着密切的关系。这为港区风研究工作开了先河,同时加强了对港区风特点的把握,有利于风灾的防范和风的有效利用。     

美国海军航母采购费知多少?

采购航母通常要考虑三个因素:航母本身的采购费;舰载机的采购费;护卫舰艇的采购费。航母的采购费通常可以根据公式进行概略计算,即常规动力航母采购费(1983年财年美元值以百万美元计)等于20.66D。D为满载排水量,以千吨为单位。按此计算.购买1艘2万吨的常规动力航母约需4亿美元。核动力航母采购费(1983年财年美元值,以百万美元计)等于20.66D 加730,即购买1艘9万吨级的核动力航母约需26亿美元。航母寿命一般按30年为限,舰载机在30年内通常要全部更新一次,舰载机的总采购费一般为航母的1.5至1.8倍。按此计算,1艘2万吨级的轻型航母的全部     

水面舰船之最

世界上最大的军舰是1989年11月服役的美国“尼米兹”级航空母舰第5艘“亚伯拉罕·林肯”号。该舰排水量为10万吨(因增加舰上装甲,其排水量比其它4艘“尼米兹”级航母多数千吨),舰长332.9米,宽40.8米,吃水11.9米,飞行甲板宽76.8米,舰员6300名,可载飞机近100架,自持力为13年,续航力80～100万海里。世界上最大的巡洋舰,是美国在40年代建造的“萨勒姆”级重型巡洋舰。该级舰共两艘,排水量为21500吨,长218.5米,宽22.9米,续航力为8000海里,舰上官兵1800人。世界上最大的驱逐舰,是美国80年代开始建造的“阿利·伯克”级驱逐舰。“阿利·伯免”号舰排水量8500吨,长156.1米     

基于船舶空气流场仿真的船舶测风偏差校正方法

船舶海面风观测易受船体和上层建筑造成的畸变气流影响,使测风数据存在偏差。针对船舶相对风测量偏差校正问题,采用CFD仿真方法研究船体周围钝体绕流气流场,量化桅杆左、右横桁实测相对风速、风向与舰桥上部参考测风点相对风速、风向偏差,利用最小二乘支持向量机分别对左、右舷测风偏差进行回归并建立校正模型。通过海上实船实验采集桅杆左、右横桁与舰桥上部测风点处的相对风测量数据,验证模型校正测风偏差的实际效果,结果表明CFD仿真建模方法能够有效降低实验船型56%的相对风速测量偏差。     

海面风应力偏离风向的观测与分析

针对海气界面风应力方向与风向不一致的现象,2015年2月4日至3月12日在南海博贺观测平台开展了综合观测,利用涡动相关法计算了海气界面风应力,并在3类大气稳定度条件下分析了风应力矢量偏离风矢量的角度变化,进一步讨论了大气层结稳定时两者角度之差与风速的参数化关系。结果表明:在大气层结稳定条件下,风应力矢量偏向风矢量左侧,且偏离角度随逆波龄和风速增大而减小;当大气层结不稳定时,风应力矢量一般偏向风矢量右侧。海气界面风应力矢量受海表面风、波浪以及大气层结的共同调制。     

Dispersal of droplets over breaking wind waves under the direct action of wind

This paper describes the dispersal of droplets over breaking wind waves under the direct action of wind, based on a comparison between the actual distribution of droplet velocity and the wind field measured in a wind-wave tank (reference wind speed 16 m sec^–1). The velocity distribution of droplets with a diameterd>0.81 mm over breaking wind waves was measured by Koga (1981). In this paper the wind field over breaking wind waves is measured by a flow visualization technique using styrofoam flakes as a tracer. The comparison allows a clear interpretation of droplet movement over the wave profile, and shows that the horizontal movement of the droplets ofd>0.81 mm is approximately determined by acceleration by the wind while their vertical movement is determined by acceleration due to gravity. These observations offer some support for the dispersion model proposed by Koga and Toba (1981).     

The wind field over wind-waves

The velocity fluctuations of wind over wind-waves in a wind tunnel are measured with a X-type hot-wire anemometer at some heights over the water surface.The observed vertical profiles of the wave-induced velocity fluctuations and the wave-induced Reynolds stress at the wave spectral peak frequency are different from those expected from the inviscid quasi-laminar model;i.e., the observed vertical profiles of the power spectral density of the wave-induced horizontal or vertical velocity fluctuations of wind have the minimum value at the height much heigher than the critical layer, and the value of the wave-induced Reynolds stress is negative at several heights over the water surface. From the comparison between the experimental results and the numerical solutions of a linear model of the turbulent shear flow over the wavy boundary, it is shown that the discrepancy described above can be attributed to the atmospheric turbulence.     

西太平洋8708号台风海面风、浪结构及其关系的遥感研究

本文以Geosat卫星高度计1987年8月11日在西太平洋海域上的-上升轨道测得的风、浪资料为基础,统计分析了8708号台风影响下的海面风速和海浪特征.结果显示,此次台风影响下的海面风速和海浪波高的空间分布具有相对台风中心近似对称的结构特征,但在台风内区,台风移动方向的右方风速较左方风速增加较快,同时在台风外围,右方风速较左方风速衰减也较快;有效波高没有明显的内、外区结构,且左、右方波高随距离变化也呈不同的衰减率;风速与有效波高的关系在台风中心左右也呈现明显的不同;本文给出了台风的风速及波高随相对台风中心距离变化的经验关系式,以及合风风速与波高的经验关系式等.     

Comparing satellite and meteorological data on wind velocity over the Black Sea

Wind-velocity data obtained from in situ measurements at the Golitsyno-4 marine stationary platform have been compared with QuikSCAT scatterometer data; NCEP, MERRA, and ERA-Interim global reanalyses and MM5 regional atmospheric reanalysis. In order to adjust wind velocity measured at a height of 37 m above the sea surface to a standard height of 10 m with stratification taken into account, the Monin–Obukhov theory and regional atmospheric reanalysis data are used. Data obtained with the QuikSCAT scatterometer most adequately describe the real variability of wind over the Black Sea. Errors in reanalysis data are not high either: the regression coefficient varies from 0.98 to 1.06, the rms deviation of the velocity amplitude varies from 1.90 to 2.24 m/s, and the rms deviation of the direction angle varies from 26° to 36°. Errors in determining the velocity and direction of wind depend on its amplitude: under weak winds (<3 m/s), the velocity of wind is overestimated and errors significantly increase in determining its direction; under strong winds (>12 m/s), its velocity is underestimated. The influence of these errors on both spatial and temporal estimates of the characteristics of wind over the Black Sea is briefly considered.     

Aircraft measurements of the microwave scattering signature of the ocean

Microwave scattering signatures of the ocean have been measured over a range of surface wind speeds from 3 m/s to 23.6 m/s using the AAFE RADSCAT scatterometer in an aircraft. Normalized scattering coefficients are presented for vertical and horizontal polarizations as a function of incidence angle (nadir to55deg) and radar azimuth angle (0degto360deg) relative to surface wind direction. For a given radar polarization, incidence angle, and azimuth angle relative to the wind direction, these scattering data exhibit a power law dependence on surface wind speed. The relation of the scattering coefficient to azimuth angle obtained during aircraft circles (antenna conical scans) is anisotropic and suggests that microwave scatterometers can be used to infer both wind speed and direction. These results have been used for the design of the Seasat-A Satellite Scatterometer (SASS) to be flown in 1978 on this first NASA oceanographic satellite.     

基于风洞试验的FPSO风载荷特性研究

当FPSO服役于目标油田时,将受到风浪流的作用力。其中,风力给FPSO一个恒定的静力,使其偏离原来的位置。风力计算在FPSO系泊系统的分析过程中是非常重要的。设计人员常常参考OCIMF进行风力计算,或者参考API规范得出。OCIMF为针对油轮的计算规范,但使用OCIMF计算FPSO风力及流力的方法,与FPSO的适应性仍需要进一步论证。API规范针对海上浮式系统,其计算风流力的方法使用也非常广泛,其原理为将FPSO上部各个模块风力叠加得出。以FPSO风载荷为研究对象,开展了风洞模型试验,获得了典型FPSO风载荷特性曲线,并将试验结果分别与OCIMF结果和API规范计算结果进行对比分析,最终给出FPSO风力计算方法的建议。本数据可用于FPSO的风力计算,也可为FPSO运动、系泊的设计研究提供参考。     

The steepness and shape of wind waves

Variations are found in the shape and the steepness of wind-generated surface gravity waves between very young waves, such as seen in a laboratory tank, and larger waves of various wave ages encountered at sea as the result of wind stress over larger fetches. These differences in the characteristic shape of wind waves are presented as a function of the wave age. The wave steepness is also expressed as a function of wave age, the measurement of which is consistent with the 3/2-power law connecting wave height and characteristic period, normalized by the air friction velocity.     

A model on the turbulent wind field over wind-waves in curvilinear co-ordinates

The wave-induced fluctuations of wind velocity over wind-waves measured in the wind tunnel experiment (Ichikawa andImasato, 1976) are compared with the numerical results estimated by a linear model (Model II) on the turbulent wind field over a dominant component of wind-waves. In the Model II, the undulation of mean air flow is introduced by adopting the curvilinear co-ordinates, and the existence of viscous sublayer and the influence of underlying wind-waves to background atmospheric turbulence are taken into account. The numerical results estimated by the Model II are in good agreement with the experimental results. The good agreement, which was not obtained from the previous model (Model I) in the Cartesian co-ordinates, is shown to be attributed to the undulating mean flow introduced in the Model II.     

Model of sand-particle separation by wind

We consider a mechanism for sand-particle separation by wind. A computational experiment has been conducted to find the possible characteristics of the structure of the mutual location of particles. We consider some scenarios for particle separation from the surface: the direct separation of particles by wind (without primary rotation) and the rolling of particles over the surface and separation after rolling. The critical wind velocities calculated for these two scenarios have made it possible to describe the probable states of surface particles as a function of wind velocity at the surface.