高压共轨柴油机喷油器零油量自学习标定策略

提出一种自学习零油量标定方法.引入发动机段加速度的概念,当发动机满足倒拖等工况条件和在标定轨压下,按一定的喷油脉宽控制喷油器进行测试喷射,通过发动机段加速度的变化判断是否有燃油燃烧,调整喷油脉宽的增减进行再次测试喷射,直到相邻两次喷射引起的段加速度的变化位于已定义阈值的两侧,最终获取在该轨压下该喷油器的零油量标定值.喷油实验台与整车实验结果对比表明,这种喷油器零油量自学习标定方法无需增加额外设备,标定精度高,实时性强.     

On-farm impacts of zero tillage wheat in South Asia's rice–wheat systems

The recent slow down in productivity growth in the irrigated areas of the Indo-Gangetic Plains of South Asia has led to a quest for resource-conserving technologies that can reduce production costs, save water and improve production. Findings from farm surveys are used to evaluate the on-farm impacts of zero tillage (ZT) wheat in the rice–wheat systems of India's Haryana state and Pakistan's Punjab province. ZT-induced effects primarily apply to the establishment and production costs of the wheat crop. Both study sites confirmed significant ZT-induced resource-saving effects in farmers’ fields in terms of diesel, tractor time and cost savings for wheat cultivation. Water savings are, however, less pronounced than expected from on-farm trial data. It was only in Haryana, India that there were significant ZT-induced water savings in addition to significant yield enhancement. The higher yield and water savings in Haryana, India result in significantly higher water productivity indicators for ZT wheat. In both sites, there are limited implications for the overall wheat crop management, the subsequent rice crop and the rice–wheat system as a whole. The combination of a significant “yield effect” and “cost-saving effect” makes adoption worthwhile and provide a much needed boost to the returns to wheat cultivation in Haryana, India. In Punjab, Pakistan, ZT is primarily a cost-saving technology for wheat cultivation. The prime driver for ZT adoption is not water savings or natural resource conservation but monetary gain in both sites. Water savings are only a potential added benefit.     

免耕法对土壤微生物和生物活性的影响

本文比较常耕和免耕法对土壤微生物和生物学活性的影响.结果表明,连续免耕6-7年的砂壤土中微生物的数量较集中分布于上表层,常耕处理则相对均匀地分布于经常翻动的土层中.0-7cm表层土壤中微生物的优势种群在两种耕法中有一定差异,特别是霉菌.免耕处理0-7cm土壤培养1天的呼吸活性是常耕处理的2.1倍,尿酶活性是常耕处理的1.6倍.但随着土层的加深,免耕处理的呼吸活性、尿酶活性下降很快,至7-14cm处分别下降56%、71%.培养40天时0-7cm土壤无机氮释放量免耕和常耕处理分别为48.1、34.5mgN/kg,而7-14cm土层则分别为21.5、29.1mgN/kg.不加碳源只加入硫铵培养3天土壤中无机氮的减少在10%左右,免耕上表层0-7cm土壤减少较多,反映土壤微生物对无机氮的固定作用.长期免耕使具有高生物学活性的土层变得浅薄,而常耕处理则较为深厚.     

不同施氮量对免耕/翻耕移栽稻生长及产量形成的影响

为探讨免耕移栽稻的氮肥管理措施和比较不同耕作方式下移栽稻的生长规律,研究了不同施氮量处理对免耕/翻耕移栽稻生长及产量形成的影响.结果表明,无论翻耕或免耕,增施氮肥可以促进分蘖的发生和叶面积的扩展;在水稻各生育时期,随着氮肥用量的增加,干物质的积累量有增加的趋势,每穗粒数和收获指数逐渐减少;水稻总吸氮量和实际产量逐渐增加,而氮肥吸收利用率、生理利用率和农学利用率及偏生产能力逐渐减小.翻耕移栽稻的分蘖能力、有效穗数和吸氮量显著高于免耕移栽稻,但翻耕和免耕对水稻产量及其构成因素的影响差异不显著,免耕移栽稻的氮肥生理利用率显著高于翻耕移栽稻.     

Effect of tillage management on energy-use efficiency and economics of soybean (Glycine max) based cropping systems under the rainfed conditions in North-West Himalayan Region

The study on energy-use efficiency and economics of soybean based cropping system, viz., soybean–wheat (Glycine max 9 L., Triticum aestivum L. emend. Fiori & Paol.), soybean–lentil (Lens culinaris Medicus) and soybean–field pea (Pisum sativum L., sensu lato), was carried out at the Hawalbagh experimental farm of Vivekananda Institute of Hill Agriculture, Almora, Uttarakhand, India during 2001–2003 (29°36′ N, 79°40′ E). These cropping systems, under rainfed conditions, were evaluated with different tillage management practices, viz., zero tillage (ZT), minimum tillage (MT) and conventional tillage (CT). Each tillage management practice, under each cropping system was evaluated for total energy output, energy input–output ratio, gross income, net income and marginal income, to variable cost of cultivation. Results revealed that the maximum energy was consumed in terms of chemical fertilizers, followed by seed and plant protection chemicals, in all cropping systems. Equivalent energy was used from literature for conversion purpose. The maximum output energy was observed in CT (44,253 MJ/ha), followed by MT for soybean–lentil cropping system (43,450 MJ/ha). The output–input energy ratio was maximum in ZT for soybean–lentil (4.9) followed by MT for soybean–pea cropping system (4.6). The economic analysis also revealed that the maximum benefits could be obtained from these sequences. Conventional tillage for all cropping sequences was found to be a better option as compared to minimum tillage and zero tillage. Benefit–cost ratios were higher in conventional tillage in all the three cropping systems. However, from the point of energy saving or cost reduction, zero tillage and minimum tillage may be considered depending on resources.     

零通量面法用于农田蒸发蒸腾量的研究

应用土壤水分零通量面的原理方法,对北京房山节水灌溉区进行了研究。通过土壤水势监测分析,显示了灌区在研究时段内零通量面的性质及其出现的空间位置。用数值方法处理了零通量面随时间变化的情况,计算了监测时段的蒸发蒸腾量,并与大田水量平衡模型法、作物系数-参考作物需水量法进行了比较。     

不同品种·系统后备绵羊零死亡率模式的效益评价

[目的]获取不同品种、系统后备绵羊在零死亡率模式下的效益评价,为养殖种羊的出售提供数据参考。[方法]选择平均初生重接近的母羔,春羔考力代43只(A)及罗姆尼24只(B对照)各1群与冬羔考力代37只(C)母羔1群,共104只。记录断奶重、月末体重、计算死亡率。到次年4月份,剔除死亡羔羊后分析7月至次年4月经济效益。[结果]A、B、C组死亡率分别为4.65%、12.5%、16.0%。罗姆尼B组与冬羔考力代C组在0.01水平上极显著差异。冬、春羔考力代与罗姆尼对照极显著差异。A组盛草期羔羊体重变异系数比B组高1.66个百分点,同时B组低于C组1.82个百分点。9月、12月、4月体重与前3个月在0.05水平上显著相关;到12月后至4月除与3月显著相关外,其他月份在0.01水平上极显著相关。6月龄出售种羊,春羔考力代平均理论利润高于罗姆尼93.21元/只,高冬羔考力代15.3元/只。12月的理论利润春羔高罗姆尼93.92元,高冬羔23.15元。在零死亡率情况下12月出售与9月出售相比,各组每只平均损失A组219.5元、B组240元、C组258元。[结论]初生重、断奶重、死亡率之间无相关性;在该地区春羔考力代绵羊具有更好的选育优势,9月(6月龄)为种羊最佳出售时机。     

Circular Disc Blade Considerations in Soil Force Prediction Modelling

Previous soil-disc force prediction models have considered spherical and concave blades, as used on disc ploughs and harrows, with many simplifying assumptions. This study proposes an approach applying the fundamental equation of earth moving mechanics for calculating the soil passive reaction acting on a rotating fiat disc blade as used on a zero-till single disc seeder. The study considers the effects of disc variable depth of cut, sweep and tilt angles, free rotation and a scrubbing reaction at the beveled edge. This paper outlines the modeling approach and prediction results for a fixed circular blade operating at 90° sweep angle over a range of speeds and at two tilt angles. To account for the varying depth across the circular disc shape width, elemental wide blade force reactions acting on wide blade segments of elemental width were integrated across the disc working width. By including inertia forces due to speed as well as additional bulldozing forces due to the loose soil accumulation in front of the blade the draught and upward vertical forces acting on the vertical disc blade were predicted with a deviation of 6%-19% and 1.5%-14% from measured data, respectively. The model was able to predict the effect of increasing the tilt angle from 0° to 20° on reducing both draught and upward vertical forces. Further development and validation of the model will be described in subsequent papers, reflecting a step by step approach of increasing complexity to model a disc blade as used on a zero-till single disc seeding system.     

Performance of a closed recirculating system with foam separation, nitrification and denitrification units for intensive culture of eel: towards zero emission

The development of a closed recirculating aquaculture system that does not discharge effluents would reduce a large amount of pollutant load on aquatic bodies. In this study, eel were reared in a closed recirculating system, which consisted of a rearing tank, a foam separation unit, a nitrification unit and a denitrification unit. The foam separation unit has an inhalation-type aerator and supplies air bubbles to the rearing water. The growth of eel, which were fed a commercial diet, was satisfactory, with gross weight increases of up three times in 3 months. The survival rate under the congested experimental conditions was 91%. The foam separation unit maintained oxygen saturation in the rearing water at about 80%. Furthermore, fine colloidal substances were absorbed on the stable foam formed from eel mucus and were removed from the rearing water by foam separation. Ammonia oxidation and the removal of suspended solids were accomplished rapidly and simultaneously in the nitrification unit. The ammonia concentration and turbidity were kept at less than 1.2 mg of N per litre and 2.5 units, respectively. When the denitrification process was operated, nitrate that accumulated in the rearing water (151 mg of N per litre) was reduced to 40 mg of N per litre. The sludge was easily recovered from the nitrification and denitrification tanks, and the components were found suitable as compost. Based on these results, the intensive aquaculture of freshwater fish such as eel can be achieved using a closed recirculating system without emission.     

不同化合态氮浓度对大豆根瘤菌结瘤和固氮作用的影响

不同化合态氮浓度对大豆根瘤菌结瘤和固氮作用的影响＊刘莉周俊初陈华癸（农业部农业微生物重点实验室,华中农业大学,武汉４３００７０）ＴｈｅＥｆｅｃｔｏｆＤｉｆｅｒｅｎｔＣｏｍｐｏｕｎｄＮｉｔｒｏｇｅｎＣｏｎｃｅｎｔｒａｔｉｏｎｏｎｔｈｅＮｏｄｕｌａｔｉｏ...