GPS/BDS分类组合定位的指数加权Helmert方差分量估计法

针对北斗卫星导航系统（BDS）星座结构复杂、不同类型卫星观测值残差差异较大的不利条件,将BDS系统中IGSO、MEO、GEO 3种卫星的观测值进行分类定权,提出一种顾及历史权比的指数加权Helmert方差分量估计法来精确确定不同系统之间观测值的权阵。为了验证该方法在GPS/BDS组合定位中的有效性,采用单点定位模型分别进行静态和动态导航实验,并将其定位结果与等权模型以及不考虑指数加权的Helmert方差分量估计方法进行对比。结果表明,采用改进的加权方法,在东、北、天3个方向的定位精度均获得显著提高,在静态条件下,相对于等权模型,改进方法3个方向的定位精度提高幅度分别达到50.0%、51.0%和42.0%;在动态条件下,定位精度提高幅度分别为10.0%、8.0%和9.0%。特别在卫星数量较少、卫星几何图形强度较差时,定位结果的改善效果更为明显。     

Nitrogen Budget in Recirculating Aquaculture and Water Exchange Systems for Culturing <Emphasis Type="Italic">Litopenaeus vannamei</Emphasis>

In order to investigate the culture characteristics of two indoor intensive Litopenaeus vannamei farming modes, recirculating aquaculture system (RAS) and water exchange system (WES), this study was carried out to analyze the water quality and nitrogen budget including various forms of nitrogen, microorganism and chlorophyll-a. Nitrogen budget was calculated based on feed input, shrimp harvest, water quality and renewal rate, and collection of bottom mud. Input nitrogen retained in shrimp was 23.58% and 19.10% respectively for WES and RAS, and most of nitrogen waste retained in water and bottom mud. In addition, most of nitrogen in the water of WES was TAN (21.32%) and nitrite (15.30%), while in RAS was nitrate (25.97%), which means that more than 76% of ammonia and nitrite were removed. The effect of microalgae in RAS and WES was negligible. However, bacteria played a great role in the culture system considering the highest cultivable cultivable bacterial populations in RAS and WES were 1.03×10¹⁰ cfu mL^?1 and 2.92×10⁹ cfu mL^?1, respectively. Meanwhile the proportion of bacteria in nitrogen budget was 29.61% and 24.61% in RAS and WES, respectively. RAS and WES could realize shrimp high stocking culture with water consuming rate of 1.25 m³ per kg shrimp and 3.89 m³ per kg shrimp, and power consuming rates of 3.60 kw h per kg shrimp and 2.51 kw h per kg shrimp, respectively. This study revealed the aquatic environment and nitrogen budget of intensive shrimp farming in detail, which provided the scientific basis for improving the industrial shrimp farming.     

基于陆海统筹的我国围填海管理

文章对比分析日本、荷兰和韩国以及我国的围填海管理情况,提出我国在围填海管理方面缺少专门法律、相关规划亟须协调和衔接、海洋管理存在交叉或缺位以及公众参与程度较低等问题;根据陆海统筹的理论内涵,分别从主管部门、规划和资源市场3个维度,对我国围填海管理进行统筹分析;基于陆海统筹建立围填海管理制度框架,重点从规划计划、项目审批、监督检查和后评估等方面加强制度建设,以期优化陆海资源配置和科学管理围填海。     

Wave-induced Maintenance of Suspended Sediment Concentration during Slack in a Tidal Channel on a Sheltered Macro-tidal Flat,Gangwha Island,Korea

A field campaign was conducted to better understand the influence of wave action, in terms of turbulence and bed shear stress, on sediment resuspension and transport processes on a protected tidal flat. An H-frame was deployed in a tidal channel south of Gangwha Island for 6 tidal cycles during November 2006 with instrumentation including an Acoustic Doppler Velocimeter, an Acoustic Backscatter System, and an Optical Backscatter Sensor. During calm conditions, the current-induced shear was dominant and responsible for suspending sediments during the accelerating phases of flood and ebb. During the high-tide slack, both bed shear stress and suspended sediment concentration were reduced. The sediment flux was directed landward due to the scour-lag effect over a tidal cycle. On the other hand, when waves were stronger, the wave-induced turbulence appeared to keep sediments in suspension even during the high-tide slack, while the current-induced shear remained dominant during the accelerating phases of flood and ebb. The sediment flux under strong waves was directed offshore due to the sustained high suspended sediment concentration during the high-tide slack. Although strong waves can induce offshore sediment flux, infrequent events with strong waves are unlikely to alter the long-term accretion of the protected southern Gangwha tidal flats.     

作为体积目标的舰船辐射噪声建模

舰船辐射噪声是由舰船上机械运转和舰船运动产生并辐射到水中的噪声,是水下目标探测系统对运动舰船进行探测、识别的基础,亦是扫雷装备需重构的重要物理场信息,具有重要的理论和应用价值。 基于舰船辐射噪声的来源和时频空域特点,将作为体积目标的舰船辐射噪声源简化为 3 个主要噪声辐射源,建立了“三亮点” 的体积目标辐射噪声模型,在保留目标主要特征的基础上,简化了重构算法的复杂性,提高了模型的实用性,可以为实验室目标探测、识别研究和扫雷装备提供较为逼真的目标数据来源。     

对抗航空磁探的磁诱饵模拟指标分析及度量方法

针对航空磁探的威胁,潜艇可通过施放能够模拟其空中磁场特性的装置(磁诱饵)进行对抗,在对磁诱饵进行研究时,需要对其模拟需求进行分析。针对此问题,在对目前常用磁探仪工作原理及优缺点进行分析的基础上建立了基于标量磁探仪的航空磁探潜模型,以所建立的航空磁探潜模型为基础,分析了对抗航空磁探时磁源所需满足的模拟需求,并给出对抗效能评估度量方法及指标:磁场功率比、磁场方向可调性指标及有效面积指标,为潜艇空中磁场模拟方法研究的开展提供了基础。     

On the electron density diagnostics of silicon <Emphasis Type="SmallCaps">viii</Emphasis> ion in solar transition region

The conditions for accurate electron density diagnostics in the solar transition region are discussed, and result shows that lines from Si?viii can provide an excellent tool for electron density diagnostics of the emitting plasma. For the Si?viii 1440.50 Å and 1445.75 Å lines, the principle of the electron density diagnostics is discussed for any intensity ratio. By the observed intensity ratio, the diagnostic results of the electron density for the quiet sun and the active region are calculated, and results indicate that in the quiet sun, the averaged electron density is \(\log (N_{e}) = 8.63\); while in the active region, the averaged density gets the maximum \(\log (N_{e}) = 8.86\) in the active region (B), and gets the minimum \(\log (N_{e}) = 8.38\) in the active region (E), where the electron density is in the unit of cm^?3. Finally, the relationship of intensity ratio and electron density is discussed, in the case of lower and higher electron density limits. This discussion is significant in the electron density diagnostics, which will be important for study on coronal heating and acceleration of solar wind.     

嵌入式硬件在环UUV模拟器的设计及实现

针对 UUV 对高逼真仿真的需求,设计了嵌入式硬件在环 UUV 模拟器。 选用 XMC4800 作为模拟器的主控芯片,设计了最小系统电路和通信接口电路。 给出了数据流图和主要软件算法,包含任务调度算法、任务优先级设计、UUV 模型选择、干扰模型选择和 CAN 应用层协议设计。 模拟器具有多种工作模式, 可以根据不同的应用场景,完成相应的硬件在环仿真,对 UUV 的研制、生产和使用具有一定的参考价值。     

西南岩溶地下水资源开发利用效应与潜力分析

西南岩溶地区面积78万km2,地下水系统包括裸露岩溶水系统和覆盖-埋藏型岩溶水系统两大类。由于降水丰富、地下岩溶发育,西南岩溶地下水资源丰富,在43万km2调查区内,具有地下水天然资源量1762.82×108m3/a,岩溶地下水允许开采资源量615.70×108m3/a。近年来,通过开展水文地质调查,在地下河、表层岩溶水和蓄水构造岩溶水打井开采方面均取得重要进展,产生了显著的经济和生态环境效应。但由于西南地区岩溶水开发难度大,区域经济落后,西南岩溶地下水的开发利用程度普遍较低,已开采量为98.32×108m3/a,仅占允许开采量的15.97%,剩余地下水潜力资源量517.38×108m3/a。     

贵州梵净山地区震旦系微量元素特征及沉积环境

为了详细研究梵净山地区震旦系沉积地球化学特征及沉积环境演化,笔者对该处永义剖面自下而上进行系统采样.样品分析结果表明该处剖面稀土元素呈轻稀土(LREE)富集,重稀土(HREE)亏损,铈总体上表现为亏损,垂向上逐渐变小,铕异常发生3次波动,表明该处震旦系沉积时总体上为氧化环境,局部沉积环境发生变化.而且陡山沱组底部"碳酸盐帽"稀土元素标准化分配模式不同于冷泉碳酸盐岩分配模式,表明两者处于不同的沉积环境,成因上无关.V/Cr、Ni/Co、U/Th及V/V Ni等微量元素比值均表明震旦系沉积时为总体上氧化环境,但垂向上仍有沉积环境及水体分层性的变化.