建制式反水雷装备发展特点分析及建议

水雷由于隐蔽性好、威力巨大、效费比高等优点,被许多国家作为重要的一种水种兵器。随着我国海军战略由近海防御向近海防御与中远海护卫转变,反水雷作战范围将延伸到第一岛链以外的海域,针对中远海的反水雷需求,我国应加紧研制建制式反水雷装备,提升编队的反水雷能力。     

基于探地雷达的土体构型无损探测方法研究

土体构型对土壤水分、溶质运移过程和作物成长等有显著影响,常规测量采用人工挖土壤剖面取样、实验室化验分析等方法,其周期长效率低。针对以上问题,以探地雷达波形及其图像为研究对象,从检测土体构型的属性(层次、层厚、土质)入手,提出了一种使用探地雷达快速测量土壤土体构型的无损探测方法。基于探地雷达波形图像的纵向梯度信息能够反应土壤分层,采用包络检波法从探地雷达回波中提取包络信号,利用Hilbert分析其瞬时相位来确定分层位置;鉴于土壤介电常数与雷达回波振幅的关系,采用探地雷达回波振幅反演各层介电常数,由介电常数推算雷达波在土壤中的传播速度,以此得到土壤剖面各层厚度;根据探地雷达波形图的图像噪声与土壤砂壤比之间存在定量关系,提出采用主成分分析方法对每一层土质的图像进行噪声估计求得各层土壤的含砂量,结合支持向量机进而辨识各层土壤土质。建立涵盖地域信息、土壤指标、探测信息、图像多特征融合信息的土体构型知识库,并编制快速识别土壤土体构型的信息系统,在内蒙古自治区呼和浩特市周边2个试验基地、6个采样点、4类土壤土体构型使用该方法进行野外探测验证。研究表明:在上述地区地表以下1 m范围内的土体构型识别正确...     

Sub-seasonal Prediction of the South China Sea Summer Monsoon Onset in the NCEP Climate Forecast System Version 2

This study depicts the sub-seasonal prediction of the South China Sea summer monsoon onset(SCSSMO) and investigates the associated oceanic and atmospheric processes, utilizing the hindcasts of the National Centers for Environmental Prediction(NCEP) Climate Forecast System version 2(CFSv2). Typically, the SCSSMO is accompanied by an eastward retreat of the western North Pacific subtropical high(WNPSH), development of the cross-equatorial flow, and an increase in the east-west sea surface temperat...     

Accelerated recruitment of copepod Calanus hyperboreus in pelagic slope waters of the western Arctic Ocean

Shelf-basin advection is essential to subsistence of the Arctic copepod Calanus hyperboreus population in high basin area. Its abundance, population structure and body size in pelagic layer were investigated with samples collected over a large range in the western Arctic Ocean during summer 2003, to evaluate the geographical variation in recruitment pattern. Calanus hyperboreus was absent from the shallow areas of the Chukchi Sea and most abundant in the slope area between the Chukchi Sea and Chukchi Abyssal Plain(CS-slope). Total abundance varied between 1 110.0 and 5 815.0 ind./m2 in the CS-slope area and ranged from 40.0 to 950.0 ind./m2 in the other areas. Early stages(CI–IV) dominated in the CS-slope area, whereas CV and adult females were frequently recorded only in deep basin areas. Geographical difference of prosome length was most evident in CIII,with average ranging from 2.48 to 2.61 mm at the CS-slope stations and 2.16–2.37 mm at the others. Abundance of early developmental stages(CI–CIV) correlated positively with Chl a concentration, but negative correlation was observed in late stages(CV–adult). Our results indicated that C. hyperboreus can benefit from primary production increase through accelerated development in the first growth season and the productive CS-slope area is a potential source for slope-basin replenishment.     

山东半岛漂浮铜藻和底栖铜藻气囊及生殖托的形态学比较分析

铜藻(Sargassum horneri)是主要分布于北太平洋西部的暖温带性海藻,是我国海藻场的重要组成物种之一,对于海洋环境、渔业资源具有重要支撑作用。除底栖生活外,铜藻可营漂浮生活。气囊和生殖托是铜藻适应漂浮生活的重要结构,但是二者与漂浮生活相适应的结构特点尚研究有限。本文对漂浮铜藻和底栖铜藻气囊、生殖托的数量以及主要形态学特征进行了统计学分析,结果显示:漂浮铜藻气囊体积显著小于底栖铜藻(P0.01),漂浮铜藻生殖托个数远少于底栖铜藻(P0.01),推测铜藻为了适应漂浮生境,其漂浮能力和有性生殖能力已经发生改变。     

基于航海应用的海图数据库比例尺分级研究

介绍了我国海图生产现状及基于数据库的海图制图技术,针对以航海图生产为主要目的的海图数据库建设中的比例尺分级问题,依据统一的样本海图选择原则,计算海部要素载负量,计算结果表明,海图载负量数值受地形、人为等因素影响大。定义一个全水深的理想海部区域,通过确定水深注记间距和载负量之间的关系、参考现有海图水深注记最小间距值和航海应用对海图比例尺分级的需求等因素,最终确定了海图数据库比例尺分级方案。     

On the intrinsic shape of the gamma-ray spectrum for Fermi blazars

The curvature of the γ-ray spectrum in blazars may reflect the intrinsic distribution of emitting electrons, which will further give some information on the possible acceleration and cooling processes in the emitting region. The γ-ray spectra of Fermi blazars are normally fitted either by a single power-law(PL) or a log-normal(call Logarithmic Parabola, LP) form. The possible reason for this difference is not clear. We statistically explore this issue based on the different observational properties of 1419 Fermi blazars in the 3 LAC Clean Sample. We find that the γ-ray flux(100 Me V–100 Ge V) and variability index follow bimodal distributions for PL and LP blazars, where the γ-ray flux and variability index show a positive correlation. However, the distributions of γ-ray luminosity and redshift follow a unimodal distribution. Our results suggest that the bimodal distribution of γ-ray fluxes for LP and PL blazars may not be intrinsic and all blazars may have an intrinsically curved γ-ray spectrum, and the PL spectrum is just caused by the fitting effect due to less photons.     

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.     

Fast adsorption of microcystin-LR by Fe(III)-modified powdered activated carbon

Journal of Oceanology and Limnology - Microcystins (MCs) are cyclic hepatotoxic peptides produced by the bloom-forming cyanobacterium Microcystis and present a public health hazard to humans and...     

Transcriptome analysis of the Chinese grass shrimp Palaemonetes sinensis (Sollaud 1911) and its predicted feeding habit

Journal of Oceanology and Limnology - Chinese grass shrimp Palaemonetes sinensis is an economically important freshwater shrimp in China. However, wild resources of grass shrimp have declined...