Modeling of A Feed Support System for Fast

As an engineering demonstrator for SKA, the Five-hundred-meter Aperture Spherical Telescope (FAST) is proposed in China. This paper is focused on one of the most critical components of FAST, the feed support system. The engineering concept, the configuration and results from model experiments are presented. The mechanical characteristics of the structure are analyzed. The performance of the feedback control system of the model is described. The feasibility of the design is tentatively confirmed by the experiments described at the end of the report.     

Experimental Research of First Feed-Support System of FAST

First feed support system, which is one of the key technologies of Five hundred meter Aperture Spherical Telescope (FAST) was discussed in this paper. A 1:30 scaled model (20 m × 20 m × 6 m) has been built to make systemic research on the feasibility of the system. The root mean square of pointing error of moving cable car was measured and the displacements of cable car within the wind speed of 8 m/s, which is the maximal wind speed of the place where the FAST will be located, were evaluated. Then the total maximal pointing error of cable car was computed. Experimental results demonstrate that the total pointing error of the cable car is less than 50 cm, the required pointing accuracy error of the system. This revised version was published online in July 2006 with corrections to the Cover Date.     

军曹鱼七种饲料原料表观消化率的研究

以0.04%的Y2O3为外源性指示剂,按照70%基础饲料:30%待测原料的比例配制成实验饲料,测定军曹鱼(Rachycentron canadum L.)对白鱼粉、虾壳粉、血粉、水解羽毛粉、酪蛋白、明胶和棉籽粕干物质、蛋白质、氨基酸和能量的表观消化率。结果表明,干物质表观消化率范围为54.1%～73.4%,鱼粉、血粉和水解羽毛粉干物质消化率最高(70.2%～73.4%),而血粉最低(P<0.05)。除血粉外各原料蛋白质表观消化率均高于85%,其中白鱼粉、虾壳粉和酪蛋白蛋白质消化率均高于90%,而血粉显著低于其它各原料(75.1%)(P<0.05)。原料氨基酸表观消化率变化趋势与蛋白质消化率相一致。能量表观消化率范围为70.6%～86.7%,白鱼粉、水解羽毛粉、酪蛋白和明胶能量消化率显著高于虾壳粉、血粉和棉籽粕,而棉籽粕能量消化率最低(P<0.05)。     

不同投喂率对细鳞鲑(Brachymystax lenok)幼鱼生长及体成分的影响

选取同一种进口鳟鱼标准饲料,设1.0%、2.0%、3.0%、4.0%和5.0%共5个投喂率水平,在溶解氧为8.0—8.5mg/L、水温为(16±0.5)℃的流水条件下,对初始体重为5.32—6.43g的细鳞鲑幼鱼进行为期35d的生长实验。结果表明,随着投喂率的增加,相对增重率(WGR)和特定生长率(SGR)先升高后降低,4.0%处理组的这两项指标显著高于其它各处理组(P<0.05),分别为289.82和3.89;饲料转化率(FCE)则呈现逐渐降低趋势,2.0%组的FCE最低,5.0%组最高。随着投饲率的增加,细鳞鲑幼鱼鱼体水分含量呈下降趋势;灰分含量无规律性变化;粗蛋白含量保持在相近水平(除1.0%处理组);粗脂肪含量无规律性变化,但3.0%组显著高于其它各处理组,4.0%组鱼体粗脂肪含量最低。综合衡量WGR、SGR和FCE等指标,认为细鳞鲑幼鱼(5—25g体重)在密度为300尾/m3、水温为(16±0.5)℃流水条件下,最适宜的投饲率为3.0%—4.0%。     

天气雷达接收功率标定的检验方法探讨

通过把测试信号输入功率换算到雷达天线喷口处接收功率的计算，由雷达气象方程可计算出其雷达反射率z值，和经雷达接收功率定标后，此测试输入功率在雷达正常观测模式显示的雷达反射率z值相比较，以检验天气雷达接收功率标定的误差是否满足技术要求。     

Productivity, management and development problems in the arid rangelands of the central Mendoza plains (Argentina)

The central Mendoza plains (56,000 km²), located in the eastern foothills of the Andes, belong to the vast phytogeographic province of ‘Monte’ (c.500,000 km²) in Argentina. This area is a typical warm arid zone and vegetation is typically a shrubland. Perennial grasses are predominantly C₄species. Land-use is for livestock grazing; the average stocking rate is 28 ha per large stock unit (LSU), year-long. Ecological and range research have been actively pursued in the region by IADIZA over the past 25 years. Two experiment stations were established 25 and 10 years ago, respectively: The Ñacuñán Biosphere Reserve and the El Divisadero Cattle and Range Station. Primary production and its relationship to climatic and edaphic parameters were analysed and compared in the two stations. Rain-use efficiency (RUE, kg DM ha⁻¹year⁻¹mm⁻¹) and useful rains efficiency (URE, P −0·1 PETp) were similar in both cases (RUE = 1·7 and 2·0; URE = 3·0 and 2·9, respectively), when herbs are concerned. However, the variability of annual production was much higher on the silty soils of Ñacuñán than on the coarse sands of El Divisadero; PRVR (Production to Rain Variability Ratio) was 2·5 and 0·53, respectively. Utilization of such experimental figures allows for the prediction of primary production and carrying capacity for a given year, based on rainfall probabilities and, therefore, to determine stocking rates in a rational manner. Basing stocking rates on annual dependable rains (f 0·8) and on useful rains probability (P − 0·1 PETp) proved to be a sound and realistic assessment, validated by long-term experiments and experience. The results of the studies on brush control, cattle diet composition, animal productivity and feed value of forage species were analysed. Current and future research programmes in IADIZA for the Mendoza plains are mentioned. Although research on resource inventory and basic ecological processes in the Mendoza plains should carry on, the emphasis and therefore the resources should henceforth be devoted to the consequences of resource management alternatives on overall arid land productivity, i.e. research for development. A better integration of applied ecology for management and investigations on basic arid land ecological processes should appear in IADIZA programmes.     

流速对封闭循环水养殖大菱鲆生长、摄食及水质氮素的影响

在封闭循环水高密度养殖条件下(平均密度14.1 kg/m²±0.51 kg/m²), 设置4 个流速梯度(200, 400,600, 800 L/h,分别以A～D 组表示), 挑选相近体质量(200.3g±7.6 g)的大菱鲆进行42 d 养殖试验, 每个梯度设置3 个重复, 每个重复55 尾鱼, 研究流速对封闭循环水养殖大菱鲆生长、摄食以及水质氮素的影响。试验结果表明: (1) 大菱鲆(Scophthatmus maximus L)特定生长率、增质量率、摄食量随流速增大先快速上升后缓升趋稳, 饲料系数则相反。B、C、D 3 组特定生长率、摄食量分别显著高于A 组30.77%～52.31%、17.30%～22.05%; 饲料系数则显著低于A 组13.83%～22.34%; (2) 养殖水体中总氨氮、非离子氨及亚硝酸氮浓度随流速的增大先快速下降后缓降趋稳。B、C、D 3 组水质总氨氮氨浓度均显著低于A 组53.70%～79.07%; (3) 根据流速对特定生长率、水体总氨氮二者的影响, 得出养殖的生态适宜流速为625 L/h。再结合流速对水循环动力的影响, 得出养殖的生态经济适宜流速为480 L/h。     

人工配合饲料与小杂鱼饲养赤点石斑鱼效果的对比试验

本试验分别以配合饲料、小杂鱼饲养赤点石斑鱼，观察不同饲料对其生长和养殖水体氮、磷含量变化的影响，经过42d的饲养，投喂配合饲料的试验组与投喂小杂鱼的对照组尾平均日增重分别为0．60、0．50g／尾，饲料系数分别为2．34、7．90。赤点石斑鱼摄食后水体中的NH3-N、NO2-N、TP含量随着其摄食后时间的延长呈先升高后下降的趋势，NH3-N、TP含量在鱼摄食后18～22h内达到高峰，NO2-N含量在鱼摄食后10～14h达到高峰。试验组水体的NH3-N含量低于对照组(p＜0．01)，NO2-N含量在排泄高峰期也低于对照组(p＜0．10)，TP含量在鱼排泄高峰期高于对照组(声＜0．05)。     

豫北沙地优质高产饲草料生产与发展模式研究

优质高产饲草料的生产是豫北沙地草食畜牧业经济有效发展的重要环节之一。根据本地区资源状况以及草食畜牧业的特点,饲草料的发展将影响着草食畜牧业发展规模、成效及在本区农业经济中所占据的地位。为此,我们着重探讨适合本区优质高产饲草料生产与有效利用模式,为地区草食畜牧业经济有序发展奠定良好的基础。