柴油机各缸工作不均匀性对NOx排放量的影响

采用高速数据采集系统实测直喷式柴油机气缸压力,通过气缸压力计算分析燃烧放热规律,建立了由放热率预测直喷式柴油机NOx排放的模型,并验证了该模型的精度与准确性。通过实测多缸柴油机各缸压力,利用该模型计算各缸在各工况下的NOx排放,分析了柴油机各缸工作不均匀性对NOx排放的影响。结果表明,多缸机由于各缸压力不均匀,其NOx排放量有一定的差别,气缸压力大,NOx排放量也大;降低柴油机各缸工作不均匀性可降低NOx排放量。     

柴油机排放CO-PM预测模型

基于柴油机一氧化碳（CO）和微粒（PM）的生成机理，建立了由CO排放浓度值预测PM值的柴油机CO－PM排放预测模型。为验证模型的有效性，在6缸增压中冷柴油机上进行了试验，计算结果与实测值较吻合。该模型对共轨式电控柴油机的仿真计算和ECU设计有一定的应用价值。     

改善单缸柴油机加速工况烟度排放的研究

单缸柴油机加速工况烟度排放增加的主要原因是低转速时较大的循环供油量。本文采用计算流体力学方法对碳烟的生成模型、燃油雾化模型和缸内燃烧模型进行数值求解,得到了加速烟度排放与循环供油量、转速之间的关系。碳烟排放随循环供油量增大而增多,高排放区主要出现在低转速区域。安装烟度限制器对新旧两种柴油机进行自由加速烟度试验。理论与试验表明：减小循环供油量的变化率可以降低烟度排放。     

柴油机的排放特征与有害排放物质控制分析

柴油机是我国应用广泛的动力机械,为现代化的生产生活提供了有效助力,随着柴油机普及率的不断提升,柴油机燃烧做功所产生的有害排放问题受到了国家和社会的广泛关注,如何有效降低柴油机的排放污染问题已成为柴油机研发的重点方向。为促进柴油机技术的升级,降低柴油机的排放危害,分析了柴油机排放污染的不利影响,说明了排放中的主要污染物的产生原理及其危害,并总结了有害排放物质的有效控制策略。     

车用柴油机排放控制对策

简要介绍了我国柴油机排放现状,以及我国柴油机排放法规导向和国外柴油机排放法规的发展,并对我国降低柴油机排放提出几点对策。     

联合Miller循环和进气道喷水改善柴油机排放研究

基于某型单缸柴油机GT-Power模型研究联合Miller循环和进气道喷水,改善柴油机排放性能,并对相关参数进行了优化。当进气门延迟关闭角为5°CA,水油质量比为30%,喷水流量为10kg/h,喷水时刻为压缩上止点前300°CA时,柴油机的排放性能最好,此时NOX排放量最大减少11.43%,Soot排放量最大减少7.5%。最后用AVL-Fire软件验证了基于GT-Power模型优化结果的准确性。     

船舶柴油机的废气排放污染防控研究

2016年,国家颁布了《船机标准》,对船舶柴油机废气排放有了新的要求.文章分析了船舶柴油机尾气排放的主要危害物种类、排放法规的实施对船舶柴油机动力装置的影响,以及柴油机有害排放的控制措施.     

降低车用柴油机排放的新技术

分析了柴油机排放及其危害,阐明了通过采用新结构和新技术可以有效控制柴油机的排放,为降低车用柴油机排放提供了可靠的理论依据。     

简析农用柴油机排放控制技术

农用柴油机广泛应用于农业生产中,由于柴油机燃料所排放的废气给空气带来了更多的污染,给环境造成了较大的压力,所以解决农用柴油机排放问题迫在眉睫。本文分析了农用柴油机排放的污染问题,对小型柴油机排放控制技术提出了一些技术方案,以缓解排放废气对空气的污染。     

供油提前角对C6121ZLG04型柴油机性能影响研究

针对C6121ZLG04柴油机在不同供油提前角下的性能研究与试验,分析了不同供油提前角对柴油机动力性、排放及油耗的影响情况.依据柴油机的工作特点和排放要求,确定了柴油机的最佳供油提前角.根据柴油机负荷特性试验对比分析,证实了在此供油提前角的情况下,在柴油机满足所要求的动力性和经济性的同时,柴油机的排放达到了欧Ⅰ排放标准.     

Review of the Egyptian experience in implementing land drainage projects

About 30 years have passed since the Government of Egypt embarked on implementing a series of large scale drainage projects. At present, about 3.8 million acres have been provided with drainage systems on the basis of systematic pre-drainage investigations and designs. The target is to provide drains in approximately 6.4 million acres in the Nile Valley and Delta.The implementation of the subsurface drainage system is carried out by the public sector and private contractors under direct supervision of governmental regional departments. The implementation process depends on many factors related to the drainage material, machinery, manpower, site requirements, farmers and organizations involved. Problems and constraints are sometimes challenging, however, the annual rate of implementation has gradually increased to 170,000 acre/year.This paper discusses the different aspects involved in the implementation process of drainage systems. The development in materials, machinery and construction technologies will be reviewed. Institutional and management factors are going to be also considered.     

Overland water and salt flows in a set of rice paddies

Cultivation of paddy rice in semiarid areas of the world faces problems related to water scarcity. This paper aims at characterizing water use in a set of paddies located in the central Ebro basin of Spain using experimentation and computer simulation. A commercial field with six interconnected paddies, with a total area of 5.31 ha, was instrumented to measure discharge and water quality at the inflow and at the runoff outlet. The soil was classified as a Typic Calcixerept, and was characterized by a mild salinity (2.5 dS m⁻¹) and an infiltration rate of 5.8 mm day⁻¹. The evolution of flow depth at all paddies was recorded. Data from the 2002 rice-growing season was elaborated using a mass balance approach to estimate the infiltration rate and the evolution of discharge between paddies. Seasonal crop evapotranspiration, estimated with the surface renewal method, was 731 mm (5.1 mm day⁻¹), very similar to that of other summer cereals grown in the area, like corn. The irrigation input was 1874 mm, deep percolation was 830 mm and surface runoff was 372 mm. Irrigation efficiency was estimated as 41%. The quality of surface runoff water was slightly degraded due to evapoconcentration and to the contact with the soil. During the period 2001–2003, the electrical conductivity of surface runoff water was 54% higher than that of irrigation water. However, the runoff water was suitable for irrigation. A mechanistic mass balance model of inter-paddy water flow permitted to conclude that improvements in irrigation efficiency cannot be easily obtained in the experimental conditions. Since deep percolation losses more than double surface runoff losses, a reduction in irrigation discharge would not have much room for efficiency improvement. Simulations also showed that rice irrigation performance was not negatively affected by the fluctuating inflow hydrograph. These hydrographs are typical of turnouts located at the tail end of tertiary irrigation ditches. In fact, these are the sites where rice has been historically cultivated in the study area, since local soils are often saline-sodic and can only grow paddy rice taking advantage of the low salinity of the irrigation water. The low infiltration rate characteristic of these saline-sodic soils (an experimental value of 3.2 mm day⁻¹ was obtained) combined with a reduced irrigation discharge resulted in a simulated irrigation efficiency of 60%. Paddy rice irrigation efficiency can attain reasonable values in the local saline-sodic soils, where the infiltration rate is clearly smaller than the average daily rice evapotranspiration.     

一种基于STM32的温室SCADA系统

借鉴SCADA系统结构,讨论了一种温室环境监控系统,系统采用CAN/1-Wire分级网络,布线方便,运行可靠;RTU以基于ARM CORTEX-M3核的STM32处理器为核心,外围模块丰富,数据处理能力强;HMI采用CAN TO USB模块,软件设计灵活,安装使用方便,同时给出了系统结构和实现关键细节。     

丹东地区玉米及水稻品种的优化选择

品种选择是农作物生产的第1步,不同品种在生育期、抗病性、抗倒性、区域适应性等方面存在较大的差异。选择适合本地区种植条件的优良品种与种子对农业生产和农民增收至关重要。结合丹东地区的实际情况,阐述在玉米、水稻品种的优化选择上应把握的原则和注意的问题,并提出相应的解决措施。     

金谷子耐旱TG118引种试种及推广应用

对引进的谷子新品种金谷子耐旱TG118进行品种比较试验和多点试种。结果表明：该品种抗旱、耐瘠、适应性强,稳产、高产、抗病抗风抗倒伏强,品质优良,粮草兼用,种植简单,省工易管;一般产量在6000kg/hm2以上,比当地主栽品种增产20%以上。最高产量达9450kg/hm2,适于在辽西北地区推广应用。     

利用三包服务期内故障数据评估汽车的可靠性

利用汽车制造企业用户服务部门提供的三包服务期内的故障数据,可以对汽车的可靠性作出评估。通过对可靠性数据的整理,运用随机过程的理论建立整车可靠性评估的数学模型,并给出了算例。     

弥雾微喷对葡萄光合特性、产量及品质的影响

为研究滴灌+冠层弥雾微喷(降温增湿措施)模式对葡萄光合特性,生理指标及产量品质的影响,试验设定微喷处理(WP1,WP2与WP3)与对照处理(CK)4个处理,在果粒膨大期测定不同处理的光合特性,果粒体积,产量与品质等数据结果显示:微喷处理胞间CO₂浓度日变化幅度均低于对照处理,微喷处理中WP1处理的胞间CO₂浓度最低;各处理的净光合速率均呈现“M”变化规律,在14:00出现“午休”现象,但微喷处理比对照处理“午休”时长较短,且WP1处理在14:00净光合速率降低幅度较小,各处理果粒体积与增长速率大小依次为WP1,WP2,WP3,CK,各处理的果粒体积增长速率均在7月15日达到最大.使用熵值法对各处理的产量与品质进行评价,各处理得分大小依次为WP1,WP2,CK,WP3.说明每日恰当的微喷处理可以显著提高葡萄净光合速率,果粒体积与果粒体积增长速率,产量与品质,但当微喷时间较长时也会影响葡萄产量与品质,因此以微喷1 h/d为最优.     

Adapting to climate change: Agricultural system and household impacts in East Africa

The East African region exhibits considerable climatic and topographic variability. Much spatial and temporal variation in the response of different crops to climate change can thus be anticipated. In previous work we showed that a large part of this variation can be explained in terms of temperature and, to a lesser extent, water effects. Here, we summarise simulated yield response in two crops that are widely grown in the region, maize and beans, and investigate how the impacts of climate change might be addressed at two levels: the agricultural system and the household. Regionally, there are substantial between-country and within-system differences in maize and bean production responses projected to 2050. The arid-semiarid mixed crop-livestock systems are projected to see reductions in maize and bean production throughout most of the region to 2050. Yields of these crops in the tropical highland mixed systems are projected to increase, sometimes substantially. The humid-subhumid mixed systems show more varied yield responses through time and across space. Some within-country shifts in cropping away from the arid-semiarid systems to cooler, higher-elevation locations may be possible, but increased regional trade should be able to overcome the country-level production deficits in maize and beans caused by climate change to 2050, all other things being equal. For some places in the tropical highlands, maize and bean yield increases could have beneficial effects on household food security and income levels. In the other mixed systems, moderate yield losses can be expected to be offset by crop breeding and agronomic approaches in the coming decades, while more severe yield losses may necessitate changes in crop types, movement to more livestock-orientated production, or abandonment of cropping altogether. These production responses are indicative only, and their effects will be under-estimated because the methods used here have not accounted for increasing weather variability in the future or changes in the distribution and impacts of biotic and other abiotic stresses. These system-level shifts will take place in a context characterised by high population growth rates; the demand for food is projected to nearly triple by the middle of this century. Systems will have to intensify substantially in response, particularly in the better-endowed mixed systems in the region. For the more marginal areas, the variability in yield response, and the variability in households’ ability to adapt, suggest that, even given the limitations of this analysis, adaptation options need to be assessed at the level of the household and the local community, if research for development is to meet its poverty alleviation and food security targets in the face of global change.     

变容量型孔轮式排种器设计与试验

为了解决针对型孔轮式排种器播量调节困难的问题,在偏心轮型孔轮式排种器的基础上,设计了一种由型孔轮和调节环（舌）组成的变容量型孔轮式排种器,以排种器的转速、调节舌类型、播量调节档位、行进速度、调节舌宽度为变量对油菜种子进行了单因素和多因素试验。试验结果表明：影响排种均匀性、各行排量一致性和种子破碎率的主要因素为排种器的转速、调节舌类型和型孔大小。变容量型孔轮式排种器的转速以30～50 r/min为宜,调节舌类型凹圆头优于平头,型孔长度增大对提高排种均匀性和各行排量一致性及降低破碎率有利。在所设计的结构尺寸条件下,该排种器适应于各类小粒度种子的条播。     

Cropcheck: Farmer benchmarking participatory model to improve productivity

In the 1970s in southern NSW, Australia, information was delivered to farmers through the transfer of technology (TOT) model. It was ‘top down’ with knowledge generated by researchers being passed onto farmers by extension officers. Farmers’ knowledge was not respected by research and extension workers. In contrast Cropcheck is a farmer participatory program which benchmarks farmer crops to identify practices for lifting yields. With TOT there was good adoption of single factor technologies such as wheat varieties but by the late 1970s to early 1980s wheat yields were stagnant or only slowly improving. There was the realisation that farmers had valuable knowledge and that multiple factors were needed to increase productivity. To address these needs in developing countries many farmer participatory models were developed. This paper, based on my experiences as an extension officer, records development in a developed country of a farmer participatory crop benchmarking model called Cropcheck. This program benchmarks farmer crops to identify the checks (best practices) related to high yields. It has been successful in lifting crop yields and profitability. This paper discusses the development of the model for irrigated wheat, i.e. the Finley Five Tonne Irrigated Wheat Club (referred to hereafter as “Wheat Club”) and adaption of the model for irrigated subterranean clover pasture, i.e. Subcheck. Since farmer participatory extension theory was undeveloped at that time, the development of the model was an intuitive learning process. The process was a planning, action and review cycle. Several years involving crop monitoring, farmer training, crop recording and reviewing results were needed to identify the objective checks consistently improving yields and gross margins. The results showed the more checks adopted the higher the yield and profitability. Farmers were trained in the learning steps of observing, monitoring, measuring, interpreting and recording their own crop practices. Farmer discussion groups were important for communication. Cropcheck has high farmer credibility because the checks are identified from farmer crops. Over a period of 6 years, yields of the “Wheat Club” increased by 50%. With Subcheck the problem of reddened subclover and inconsistent production disappeared. The Cropcheck model has been adapted for many crops in eastern Australia. Precision agriculture and electromagnetic mapping and geographic information systems (GIS) have followed on as new technology and monitoring tools for farmers but it is still important to ground truth these technologies with crop monitoring.