共查询到20条相似文献，搜索用时 93 毫秒
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生物质成型燃料是煤和天然气优秀的清洁替代能源,其技术的研究得到世界越来越多的关注和重视。在生物质成型过程中,生物质化学成分的含量与其成型质量有着密切关系,不同的生物质由于化学成分含量不同,决定了要采用不同的加工参数才能形成高品质的成型燃料。为此,首先介绍了生物质成型燃料的整个加工过程,并全面分析各主要的加工参数(原料含水量、颗粒粒径、温度和压力)对成型燃料品质的影响。同时,介绍了目前被广泛运用于生物质颗粒成型研究的3个成型模型,为进一步探究不同生物质的成型规律及成型条件,优化最佳加工参数提供理论依据。 相似文献
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生物质成型燃料加工技术分析研究 总被引：2，自引：0，他引：2
阐述了生物质成型燃料国内外发展现状、生物质成型燃料加工技术与装备的特点与使用对象;重点分析了现有的生物质成型燃料加工技术和装备在实际应用中的优缺点,得出目前我国的生物质固化成型装备在设备的实用性、系列化、规模化上还很不足,距国际先进水平还有不小的差距;这一问题以成型机最为突出,表现在生产率低、成型能耗高、主要工作部件寿命短、机器故障率多、费用高等方面;并依据生物质成型燃料发展趋势,提出目前我国生物质成型燃料加工设备的设计要点为：一是加工设备的原料适应性,二是加工设备的先进性与性价比。 相似文献
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生物质固体成型燃料的关键技术及可行性 总被引：1，自引：0，他引：1
生物质固体成型燃料技术是生物质能开发利用的一项重要技术,具有广阔的发展前景。在介绍生物质成型燃料技术研究发展现状及比较分析国内外几种成型燃料生产技术的基础上,讨论并总结了生物质固体成型燃料的关键技术,分析了该项技术在我国推广应用的可行性。 相似文献
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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. 相似文献
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Overland water and salt flows in a set of rice paddies 总被引：1，自引：0，他引：1
E. Playn O. Prez-Coveta A. Martínez-Cob J. Herrero P. García-Navarro B. Latorre P. Brufau J. Garcs 《Agricultural Water Management》2008,95(6):645-658
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. 相似文献
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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。 相似文献
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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。 相似文献
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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。 相似文献
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利用三包服务期内故障数据评估汽车的可靠性 总被引：2，自引：0，他引：2
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。 相似文献
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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. 相似文献
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Adapting to climate change: Agricultural system and household impacts in East Africa 总被引：4，自引：0，他引：4
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. 相似文献
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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。 相似文献