基于GNSS差分定位的天气雷达坐标精确定位研究

天气雷达天线馈源的精确定位关系到雷达数据的精确使用和天气雷达全网拼图的使用效果.目前,国内新一代天气雷达天线馈源坐标基本都是使用GNSS(GLobal Navigation Satellite System)系统中的美国GPS(Global Position System)系统接收机,在雷达塔楼楼顶单点瞬时定位测量得到的,误差一般大于30 m.为了提高定位精度,将GPS精确定位技术与全站仪测量相对高度结合起来,提出了一种测量天气雷达的馈源坐标的方法,可使天线馈源的海拔高度测量精度达到10 m以内.使用这种方法对北京市气象局S波段新一代天气雷达天线馈源坐标进行了实地测量,精度达到设计要求.     

Predicting and forecasting flow discharge at sites receiving significant lateral inflow

Two models, one linear and one non‐linear, were employed for the prediction of flow discharge hydrographs at sites receiving significant lateral inflow. The linear model is based on a rating curve and permits a quick estimation of flow at a downstream site. The non‐linear model is based on a multilayer feed‐forward back propagation (FFBP) artificial neural network (ANN) and uses flow‐stage data measured at the upstream and downstream stations. ANN predicted the real‐time storm hydrographs satisfactorily and better than did the linear model. The results of sensitivity analysis indicated that when the lateral inflow contribution to the channel reach was insignificant, ANN, using only the flow‐stage data at the upstream station, satisfactorily predicted the hydrograph at the downstream station. The prediction error of ANN increases exponentially with the difference between the peak discharge used in training and that used in testing. ANN was also employed for flood forecasting and was compared with the modified Muskingum model (MMM). For a 4‐h lead time, MMM forecasts the floods reliably but could not be applied to reaches for lead times greater than the wave travel time. Although ANN and MMM had comparable performances for an 8‐h lead time, ANN is capable of forecasting floods with lead times longer than the wave travel time. Copyright © 2007 John Wiley & Sons, Ltd.     

Turbot Scophthalmus maximus：stocking density on growth, pigmentation and feed conversion

1 INTRODUCTION Turbot is a type of marine flatfish naturally distributing along the coastal area of European. It is highly demanded for good taste. The price therefore, is very expensive. To meet the consump- tion, large-scale turbot cultures were perform…     

Model Validation and Performance Evaluation for The Multi-Tethered Aerostat Subsystem of the Large Adaptive Reflector

The Canadian design for the Square Kilometre Array radio telescope includes a large multi-tethered aerostat to support the telescope’s receiver. To validate this design concept, two parallel tracks have been undertaken: a numerical simulation of the multi-tethered aerostat system has been assembled, and a one-third scale prototype of the system has been constructed. This paper describes the experimental facility, presents results from initial tests of the uncontrolled system and compares these results to the predictions of the computer model of the system. Generally, the results compare very favourably. Using the simulation, we arrive at two important design philosophies to be used in the design of the full-scale system: (a) perturbations on the confluence point should be minimized, and (b) the system stiffness should be maximized to ensure minimum response to disturbances.     

Reduced growth in hybrid tilapia (Oreochromis mossambicus ×O. Niloticus) at intermediate stocking density

Hybrid tilapia were reared at densities of 1, 5 or 10 fish per tank for four weeks. Mortality was 0 at 1 and 10 fish per tank, but was 25% at 5 fish per tank. Specific growth rate was highest at 1 fish per tank, and lowest at 5 fish per tank. The lower growth rate at the intermediate stocking density was associated with reduced feed efficiency, but there was no reduction in feed intake or digestibility. The results suggested increased metabolic cost caused by aggressive behaviour at intermediate stocking density, which can be suppressed by a further increase in density. This project was financially supported by the State Key Laboratory of Freshwater Ecology and Biotechnology of China and by Shanghai Fisheries University (Project SFU. 200003).     

黑水虻在水产饲料中的应用进展

总结黑水虻的生物特性、营养成分含量及其在水产饲料中的应用,简述黑水虻幼虫不同产品形式(干虫/虫粉、脱脂虫粉、虫油、鲜虫/虫浆)在草食性、杂食性、肉食性和甲壳动物饲料中的应用进展,阐述在水产动物饲料中适量添加黑水虻可提高所饲动物的生长性能,过量添加则引起动物发生病理性变化,综述在不同水生动物中黑水虻的最适添加量,提出黑水虻在产业化生产及水产饲料中的应用前景及问题。     

ESR dating of optically bleached quartz grains from Plio-Pleistocene to Holocene coastal dune deposits (Wilderness-Knysna area,South Africa): a comparison with luminescence

Five Plio-Pleistocene to Holocene aeolian quartz samples from the coastal dune deposits of the Wilderness-Knysna area (South Africa) previously dated by OSL were selected for ESR dating. Samples were processed following the Multiple Centre approach and using the Multiple Aliquot Additive dose method. Aluminium (Al) and Titanium (Ti) signals were systematically measured in all samples.Our study shows that ESR results obtained for Middle Pleistocene to Holocene samples may be strongly impacted by (i) the presence of a significant high frequency noise in the ESR spectra acquired for the Ti signals and (ii) the choice of the fitting function employed. In particular, if not taken into account, very noisy spectra can lead to a significant overestimation of the true ESR intensity measured for the Ti–H signal. These sources of uncertainty are however not sufficient to remove the ESR age overestimations. Consequently, our results indicate that the Al and Ti ESR signals of these quartz samples have not been fully reset during their aeolian transport.While this work contributes to improve our understanding of the ESR method applied to quartz grains, and especially of the potential and limitations of the Ti signals, it also provides additional baseline data to illustrate the existing variability among quartz samples of different origins or sedimentary context. Our results are consistent with previous studies by confirming that the Ti–H signal shows the best potential for the evaluation of low dose values (<100 Gy for these samples), whereas it becomes inappropriate for the higher dose range, and the Ti–Li–H (option D sensu Duval and Guilarte, 2015) should be used instead.Beyond the methodological outcome, this ESR dating study also provides a useful addition to the existing chronology of the aeolian deposits in this region. In particular, new (and possibly) finite numerical age results were obtained for the two oldest samples, constraining the aeolianite landward barrier dune and the coversand formations to the MIS 10-8 and Pliocene, respectively.     

海啸波作用下岸滩演变与床沙组成变化研究综述

从海啸波作用下岸滩演变、床沙组成变化、建筑物周围淘刷和数值模拟研究4个方面,总结分析了国内外的研究现状和最新进展,指出可控环境下的实验和数值模拟研究相对较少、床沙组成变化缺乏关注、建筑物周围局部冲刷机理认识不足、缺少多尺度数值模拟计算等是当前研究存在的主要不足。在特大型波浪水槽内开展实验研究、发展多尺度混合数学模型、完善海啸波作用下的泥沙输移计算理论等是未来研究取得突破的关键方向。     

胡安·德富卡洋中脊富锌烟囱体流体通道演化特征

对采自Faulty Towers(47°57.447'N,129°6.568'W)硫化物烟囱群一个不再活动的烟囱体硫化物开展了详细的矿物学和地球化学研究。样品从外壁往内壁方向可划分为4个矿物组合带,分别为重晶石-无定形硅-铁氧羟化物带;白铁矿-黄铁矿-无定形硅-重晶石带;白铁矿-黄铁矿-闪锌矿-纤锌矿带;纤锌矿-黄铜矿-白铁矿带。从底部到顶部,样品通道形态主要有3种:不规则、不连续的多通道;椭圆形单通道;封闭的通道。矿物学研究证实,烟囱体以低温矿物组合白铁矿、纤锌矿为主,高温矿物黄铜矿少见,仅局限分布在流体通道附近。210Pb定年结果表明,烟囱壁形成经历较短时间(约3 a),而通道的闭合则经历了相对长的过程(约17 a)。结合矿物学研究,最终恢复了整个尖塔结构的生长历史。     

Breeding and mass scale rearing of clownfish Amphiprion percula: feeding and rearing in brackishwater

Breeding and mass scale larval rearing of clownfish Amphiprion percula is very limited in brackishwater. We designed an indoor program of A. percula culture in brackishwater with a salinity of 24±1, during which the impacts of feed type, water temperature, and light intensity, on the efficiency of its reproduction, were revealed. The fish were accommodated along with sea anemones in fibre glass tanks to determine the influence of brooder diet on breeding efficiency. Higher reproductive efficiency [number of eggs laid (276 22.3 eggs)] was observed when fish were fed live Acetes sp. rather than clam (204 16.4 eggs), trash fish (155 12 eggs) and formulated feed (110 10 eggs). The spawning rate was increased during September and October (water temperature, 28.74 0.55°C) on average of 2.4 spawning per month; and low spawning rate was in January (water temperature, 24.55 0.45°C) on average of 1 spawning per month. Among three light intensities (100, 500, and 900 lx) set to evaluate larval survival rate, larvae showed the highest survival rate (65.5%) at 900 lx. The breeding method specifically in brackishwater developed in the present study is a new approach, will help the people from the regions of estuary and backwater to enhance their livelihood and it will lead to reduce the exploitation from the wild habitat.