不同日粮组合对杂交肉牛生长性能的影响

对肉牛饲料进行营养价值评定,并选择55头西门达尔杂交肉牛分5组进行试验,研究不同日粮组合对杂交肉牛生产性能的影响。结果显示,肉牛代谢体重干物质采食量与日粮粗蛋白含量之间存在极显著正相关关系,日增重随代谢体重采食量的增加呈直线增加,经济效益随肉牛日增重的增加呈直线增加。以秸秆 野草 0.7 kg玉米面、秸秆 野草 0.5 kg肉牛浓缩料、秸秆 牧草 0.5 kg肉牛浓缩料、秸秆 野草 2 kg肉牛精料补充料和秸秆 牧草 2 kg肉牛精料补充料5种日粮组合分别饲喂西杂肉牛63~75 d,日增重分别为0.14,0.32,0.63,0.90和1.08 kg,体况评分分别增加0.10,0.17,0.33,0.48和0.77分,日盈利分别为-0.36,0.76,3.07,5.74和6.13元。结果表明,在传统饲养模式下,改善粗饲料品质、补充含蛋白质和矿物质的精料可显著提高肉牛生产性能和经济效益。     

Theoretical analysis of a tri polar parallel gear pump

Common gear pumps have numerous shortcomings, including poor flow quality, high unbalanced radial force, imbalanced “balanced compound gear pumps” with complex structure, many leakage points, high manufacturing and assembling precision, high cost, and difficulty using in industrial applications. This paper proposed a new design scheme of a parallel gear pump with three sub structures. Based on the design model, theoretical analysis of structural principles, power density, radial force, flow characteristics, and flow fluctuating were carried out. The result shows the new pump design has the advantages of small axial size, high power density, the initiative gear balanced the gear radial force, and decreased the radial force of the driven gear. By selecting suitable numbers of teeth, it can reduce flow pulsation effectively and improve flow quality.     

茶树重修剪机的研制概况

茶树的重修剪是改造衰老茶树的重要措施之一.针对茶树重修剪机械的研制进展与研究内容,叙述了几款茶树修剪机的工作结构与传动机构,以及国内修剪机在刀片结构与整机结构上的改进措施,并介绍了一款最新研制的针对老茶树进行重修剪操作的推轮式重修剪机的结构特点.     

杉木完全双列杂交组合苗期性状遗传效应分析

以广西全州县成水林场种子园81^#、91^#、104^#、143^#和250^#五个杉木优树作为杂交亲本,按照5×5完全双列交配设计进行控制授粉,得到25个杂交组合。1998年在广西苍梧县白南林场进行育苗试验,测定苗期性状,估算亲本的一般配合力、特殊配合力及遗传力等遗传参数,根据子代一般配合力效应值和特殊配合力效应值,在25个杂交组合中初选出91×81、250×104、91×250、143×104、143×81、81×250组合为最佳杂交组合,为杉木第二代强化种子园的亲本选配提供理论依据。     

静止无功发生器的H2/H∞保性能控

在电力系统中装设(Static Synchronous Compensator) STATCOM可以改善系统的暂态稳定性、动态性能,维持系统电压,以及提高传输能力。为了更好的利用该装置,文中利用H2/H∞保性能控制理论和直接反馈线性化,在单机－无穷大系统中建立了含有不确定因数的STATCOM数学模型。采用LMI方法,得出H2/H∞保性能控制规律。仿真表明,这种控制方法同时具有鲁棒性和最优性能,降低了单纯H∞控制方法的保守性,提高了电力系统的稳定性,并能满足电压精度的要求。     

M3、ASI法测定土壤养分数据的应用初报

将M3、ASI方法测试土样数据与常规方法测试的数据比较,得出其相关性。其中:磷R(旱田)=0.938779,R(水田)=0.905098;钾R(旱田)=0.865785,R(水田)=0.928413。按照公式将M3方法测试的磷钾数据转换成常规方法数据,并以常规方法评价指标为依据,解决了磷钾数据应用问题。氮的数据经比较没有相关性,可对照土壤有机质、速效氮的分级指标与氮素推荐量,根据目标产量和农户实际用肥量,提出氮的推荐量。     

土地利用方式对土壤团聚体组成及质量的影响

分析了福建省建瓯市土地利用方式对土壤团聚体组成及水稳性的影响,结果表明,林地有利于形成大粒径土壤团聚体,而柑橘园、茶园、坡耕地形成的土壤团聚体粒径较小。不同土地利用方式对土壤团聚体的质量有较大影响:>2 mm水稳性土壤团聚体含量和土壤团聚体平均重量直径的顺序都为:木荷林>封育林>杉木林>柑橘园>茶园>坡耕地。平均重量直径与>0.25 mm水稳性土壤团聚体含量存在极显著的线性正相关关系。     

滴灌大豆需水规律及灌溉制度研究

在滴灌条件下,分别设置295 mm、345 mm、395 mm、445 mm这4个不同的灌水处理;同时设置1个沟灌处理为对照,对不同灌水量处理的大豆田间土壤水分动态及大豆田间耗水规律进行分析研究,初步确立在石河子地区,滴灌大豆适宜的灌溉制度参数为:灌溉定额为395～445 mm,灌水定额为35～45 mm,苗期和成熟期取下限,灌水周期为7 d;花荚期和鼓粒期取上限,灌水周期5 d,整个生育期灌水13次.     

Scheme of Weather-Based Indemnity Indices for Insuring Against Freeze Damage to Citrus Orchards in Zhejiang, China

We design a weather-based indemnity index for the insurance against freeze damage to citrus orchards so as to provide technological support for the development of policy-based agriculture. The indices are prepared by separating a relative meteorological yield from the yield that is dependent on tree age, high-yield and low-yield years, and environmental factors, and then using a risk assessment scheme to determine the percentage yield reduction due to the meteorological hazard. We thus develop a set of indices associated with cold temperature damage with which to construct more severe weather indices in conjunction with the yield percentage decrease. We then combine the insured regional citrus yield index with the insured meteorological counterpart to obtain a weather-based indemnity index for the varying degree of freeze damage to crops. When the freeze damage index （FDI） is greater than -7.0℃ for the coastal belt of Zhejiang Province, China, or greater than -9.0℃ for other regions of Zhejiang, weather-based indemnity index （WBII） is zero, meaning there is no compensation; when the FDI is from -7.0 to -7.9℃ for the coastal belt or from -9.0 to -9.9℃ for other regions, the WBII is 1 with 50% compensation; when the FDI is from -8.0 to -8.9℃ for the coastal belt or from -10.0 to -10.9℃ for other regions, the WBII is 2 with 70% compensation; and when the FDI is less than -9.0℃ for the coastal belt or less than -11.0℃ for other regions, the WBII is 3 with 90% compensation. The weather indemnity indices of insured orchards are developed in the interest of owners, thereby eliminating adverse selection and moral hazard issues and providing timely recompense from the insurer, and resolving the problem of high indemnity cost in agricultural insurance.