冬小麦推迟春季首次灌水后不同品种的产量及水分利用效率

１９９１～１９９３年研究表明，即使两年度均为小麦生育期降水较少年份，且冬、春降水很少，在相同灌水量条件下，首次灌水推迟至拔节期或稍后１０日左右，小麦仍可获得高产，并提高了水分利用效率；在减少供水７５ｍｍ情况下，仍可维持高产而水分利用效率进一步提高。总的来看，随着首次灌水推迟，水分利用总量降低，而水分利用效率却因产量和水分利用而协调变化。品种对首次灌水推迟的反应不同：高产中早熟和前期对水分胁迫适应性强的品种更适于高产节水栽培，可将春季首次灌水推迟至拔节后挑旗前；晚熟大穗大粒型品种不宜推迟春季首次灌水，以免减产。     

Algorithm for Symbol Timing and Carrier Phase Offset Acquisition for OQPSK Modulation

In high-rate digital mobile burst communication, it is important to acquire the symbol timing and carrier phase offset rapidly. This paper presents an algorithm of symbol timing and carrier phase offset acquisition for OQPSK. Proposed algorithm is parallel and has advantages over serial system that recover the carrier phase offset, and then estimate the symbol timing. This algorithm is easy to realize by using digital technology.     

配气正时对汽油机性能影响的研究

为了改善车用发动机的性能指标,以内燃机仿真软件BOOST为平台,建立了四缸汽油机的工作过程仿真模型,并通过模拟计算研究了进气正时对汽油机充量系数、扭矩和燃油消耗率的影响.研究结果表明,在发动机转速较低时,发动机的充量系数和扭矩随着进气正时的提前有不同程度的提高;而在发动机转速较高时,发动机的充量系数和扭矩会随着进气正时的推迟有不同程度的提高.计算结果为汽油机的改进和优化提供了依据.     

Effect of straw management, tillage timing and timing of fertilizer nitrogen application on the crop utilization of fertilizer and soil nitrogen in an irrigated cereal rotation

In irrigated grain-growing soils on Canada's prairies, straw management can affect nitrogen (N) fertility and long-term soil organic matter reserves. We conducted a 2-year field experiment in southern Alberta, on a Dark Brown Chernozemic Lethbridge loam (Typic Boroll), to determine the effects of straw removal, tillage, and fertilizer timing on crop uptake of soil and fertilizer N. During the study (1991 and 1992), the crop was oat (Avena sativa L.) and wheat (Triticum aestivum L.), respectively, in an experiment that had been in a wheat-wheat-oat-wheat rotation since 1986. Five straw-tillage treatments were: straw-fall plow, straw-pring plow, no straw-fall plow, no straw-spring plow and no straw-direct seeding. Fertilizer N was applied in fall or spring. Ammonium nitrate (5 at.% ¹⁵N) was added at 100 kg N ha⁻¹ in fall 1990 or spring 1991. For oat (1991), plant N derived from soil was higher under fall plow than under spring plow, higher with tillage than direct seeding, and unaffected by straw removal. The plant N derived from fertilizer was not affected by straw removal in fall plow treatments, but under spring plow, it was higher with straw removal. The plant N derived from fertilizer showed a significant straw-tillage × fertilizer timing interaction; with fall incorporated straw, plant N derived from fertilizer was 44.0 kg N ha⁻¹ for spring-applied, and 30.6 kg N ha⁻¹ for fall-applied N, but in other straw-tillage treatments there was no effect of fertilizer timing. Cumulative fertilizer N recovery (plant + soil) over the 2 years averaged 64.2%, and was unaffected by straw-tillage treatment. Fertilizer N recovery, however, was less with fall-applied N (61.3%) than spring applied N (66.8%). At mid-season, fall plow treatments had higher soil inorganic N and inorganic N derived from fertilizer than spring plow treatments, apparently because of less immobilization. The fall plow treatments also retained higher inorganic N after harvest. Straw removal and fertilizer timing did not influence soil inorganic N and soil inorganic N derived from fertilizer. N removal in straw (16 kg N ha⁻¹ yr⁻¹) could deplete soil N in the long-term. Long-term effects of tillage timing on soil N will depend on the relative amount of N lost by leaching with fall plowing and that lost by denitrification under spring plowing. With direct seeding, crop yield and uptake of soil N was less, and N losses by denitrification could be greater. Application of N in spring, rather than fall, should enhance crop N uptake, reducing N losses and enhancing long-term soil organic N.     

关于“星火技术”国际转移的几点思考和建议

简要论述了当代国际技术发展的政治、经济背景,现状及发展趋势。特别论述了发展中国家对技术需求的变化,提出了我国星火计划国际转移的可能性、现实性,并提出了我国星火技术国际转移的6条建议。     

Optimizing farmyard manure utilization by varying the application time and tillage strategy

Abstract. Two field experiments were carried from 1999 to 2001 to assess the effectiveness of autumn, winter and spring application of straw-based farmyard manure (FYM). The soil was a sandy loam containing 106 g clay kg⁻¹ situated in the temperate coastal climate of Denmark. The FYM was applied manually to experimental plots at a target rate of 300 kg N ha⁻¹. The manure was incorporated by three initial tillage strategies (harrowing, rotavating or no-tillage) prior to ploughing. All combinations of tillage strategies were also carried out without manure application. Spring barley ( Hordeum vulgare L.) was grown, followed by ryegrass ( Lolium perenne L.). The results suggest that, as far as circumstances permit, FYM should be applied in spring to achieve the optimum use of nitrogen in the manure. Further, yield and nitrogen uptake did not benefit from harrowing or rotavating the manure before ploughing. When manure was not applied, soil tillage prior to ploughing did not significantly affect grain yield or nitrogen uptake.     

Modelling hunting strategies for the conservation of wild rabbit populations

Recently, European wild rabbit (Oryctolagus cuniculus) populations have undergone a sharp decline that may be exacerbated by hunting. We investigate the effects of the timing of hunting on the conservation of wild rabbit using a model for rabbit population dynamics. Scenarios with different hunting rates and age strategies were simulated for different population qualities. We interviewed hunters to ascertain the degree to which they would accept a change in the timing of hunting. We also investigated the hunting pressure applied by hunters and its relationship with rabbit abundance. Modelling results indicate that the current hunting season has the greatest impact on rabbit abundance. Hunting in late spring optimises hunting extraction while conserving rabbit populations. When the rabbit population quality is low the effects of age strategies and the timing of hunting are less important than the effect of the hunting rate applied. Almost half the hunters would agree to policy changes. More than 75% of hunters implemented self-imposed hunting restrictions to improve rabbit populations, that were more frequently applied in high rabbit abundance areas. Therefore, changing the timing of hunting and increasing the participation of hunters in low abundance areas could optimise both the exploitation and the conservation of wild rabbit populations in southwestern Europe.     

不同施氮时期对冬小麦子粒蛋白质组分及其动态变化的影响

2002～2003年在新疆乌鲁木齐和昌吉两个试验点,进行新疆不同栽培条件下氮肥施用时期对冬小麦子粒产量和蛋白质组分变化的研究。试验结果表明,在氮肥施用量一定的情况下,拔节期施氮处理小麦产量显著高于返青期和孕穗期施氮的处理,说明拔节期施氮有利于实现小麦高产。在新疆冬小麦栽培条件下,随施氮时期后移,子粒清蛋白和球蛋白含量有所减少,而醇溶蛋白和麦谷蛋白的含量增加;孕穗期施氮可以明显提高子粒麦谷蛋白的含量,有利于小麦加工品质的改善。不同施氮时期对小麦产量和品质的影响不同,施氮时期后移能提高小麦子粒的麦谷/醇溶比值;但不同品种在不同地区种植,其施氮时期后移的效应存在一定的差异。     

电控单体泵多节点标定系统的研发

随着车载电控单元数量的增多，实现多节点同时标定有利于汽车不同ECU间的参数匹配优化，在设计了TouCAN模块与CAN总线硬件接口的基础上，结合CCP协议，通过设置位时间、不同的节点站地址、收发报文缓冲器的标识符及屏蔽寄存器，设计并实现了多个ECU的通信和标定，提高了标定效率。     

天然气发动机预燃室式燃烧系统的研究

开发了火花点火天然气发动机预燃室式燃烧系统。该发动机通过采用新型的预燃室式燃烧系统，同时对发动机的燃料供给系统、点火系统等进行改进设计，实现了两级点火和稀燃、速燃，大大提高了燃烧速度，从而改善了发动机的动力性，降低了排气温度和排放量。试验结果表明，新的天然气发动机的动力性与原机基本相当，排气污染降低，经济性良好。