基于HyperWorks的耕整机机架组合式优化分析

耕整机机架的轻量化和高强度化是机架设计的目标之一。在CATIA中建立了简化的几何模型,用Hy-perMesh对其前处理建立了有限元模型。以模态分析理论为基础,通过有限元软件HyperWorks对机架进行了模态分析,考察了该机架的刚度特性,并用拓扑优化中的变密度法,通过HyperWorks对耕整机机架进行了拓扑与形貌的组合分析,得到了高刚度和轻质量的设计方案。     

基于ANSYS的2BYFGJ-4型播种机机架优化设计

以2BYFGJ-4型玉米苗带秸秆还田旋耕施肥播种机机架为主要优化分析对象,通过有限元分析软件ANSYS对其进行静力学分析和模态分析,得出该机机架设计的薄弱环节。根据前几阶模态频率和振型,提出机架的优化方案,并以模态频率为衡量指标对各方案进行比较分析。结果表明:优化后的机架具有更好的动态性能,可为下一轮样机制作提供重要依据。     

Using auction mechanisms to reveal costs for water quality improvements in Great Barrier Reef catchments in Australia

There is increasing interest in the use of market-based instruments such as tenders and trading systems to address water quality issues. While the focus is typically on the improvements in resource allocation that are generated, these instruments also play an important role in addressing issues of asymmetric information. The use of water quality tenders to reveal the opportunity costs of changing agricultural practices can help policy makers to understand the potential costs of misallocating public resources and to design better ways of achieving water quality improvements. This role of water quality tenders to reveal opportunity costs is demonstrated by reporting four pilot applications to improve water quality into the Great Barrier Reef in Australia. The results demonstrate the potential for opportunity costs to vary substantially between agricultural producers, and across industries, catchments and pollutants. The results from these case studies indicate that the most cost-effective water quality improvements may be generated from the horticulture and dairy sectors. In contrast, the opportunity costs of reducing emissions from the cane and grazing industries appear to be higher.     

Yield and soil system changes from conservation tillage in dryland farming: A case study from North Eastern Tanzania

Yield levels in smallholder farming systems in semi-arid sub-Saharan Africa are generally low. Water shortage in the root zone during critical crop development stages is a fundamental constraining factor. While there is ample evidence to show that conservation tillage can promote soil health, it has recently been suggested that the main benefit in semi-arid farming systems may in fact be an in situ water harvesting effect. In this paper we present the result from an on-farm conservation tillage experiment (combining ripping with mulch and manure application) that was carried out in North Eastern Tanzania from 2005 to 2008. Special attention was given to the effects of the tested treatment on the capacity of the soil to retain moisture. The tested conservation treatment only had a clear yield increasing effect during one of the six experimental seasons (maize grain yields increased by 41%, and biomass by 65%), and this was a season that received exceptional amounts of rainfall (549 mm). While the other seasons provided mixed results, there seemed to be an increasing yield gap between the conservation tillage treatment and the control towards the end of the experiment, and cumulatively the yield increased with 17%. Regarding soil system changes, small but significant effects on chemical and microbiological properties, but not on physical properties, were observed. This raises questions about the suggested water harvesting effect and its potential to contribute to stabilized yield levels under semi-arid conditions. We conclude that, at least in a shorter time perspective, the tested type of conservation tillage seems to boost productivity during already good seasons, rather than stabilize harvests during poor rainfall seasons. Highlighting the challenges involved in upgrading these farming systems, we discuss the potential contribution of conservation tillage towards improved water availability in the crop root zone in a longer term perspective.     

2BMQJ6型气吸式玉米免耕播种机的研制

针对现有的型孔轮式、组合内窝孔式玉米免耕播种机对种子尺寸要求高、适应性差等问题,研制开发了一种对种子尺寸要求低、适应性强的用于小麦收割后直接播种的气吸式玉米免耕播种机。该机主要由机架、风机、划印器、播种单体、施肥系统和传动系统等组成,可一次性完成破茬、施肥、开沟、播种、覆土、镇压等作业。田间试验结果表明:该机的粒距合格指数≥8 5%,重播指数≤1 0%,漏播指数≤5%,种子破损率≤0.5%,性能指标优于行业标准;机具结构设计合理,作业时土壤扰动小,满足高速精密播种质量要求。     

保护性耕作模式下非化学除草技术的研究

随着保护性耕作技术的发展,杂草问题逐渐成为影响保护性耕作效益的重要问题,大规模使用除草剂导致的抗药性和环境污染问题,日益受到重视。为此,综合分析了在保护性耕作技术模式下,国内外采用的各种非化学除草技术的特点和发展现状,从而为确定适合我国特色的除草技术提供技术指导。     

农田轻便土壤悬虚镇压器的研制与应用

针对目前旋耕机大面积应用造成的农作物播前或播后土壤悬虚现状,提出了农田轻便土壤悬虚镇压器研制的指导思想。研制出的镇压器主要包括牵引装置、轴承、压辊装置3部分,可满足不同农田所需镇压深度的要求,并对其提出了合理的工作参数。该机具克服了以住镇压辊质量固定、携带不便等缺点,灵活轻便、无需配套动力、生产和作业成本低、作业效率高,经不同农田镇压效果良好。     

1 GSTN-325型深松施肥型多功能复式作业机的研制

为了提高作业效率,适应大马力拖拉机对配套农机具的需求,在分析研究中小型单一和组合作业模式整地机的基础上,设计了一种深松、施肥型多功能复式作业机。同时,介绍了其整体结构和工作原理,并对主要工作部件的参数进行了设计和计算。该机一次进地可完成灭茬、旋耕、深松、施肥、起垄和镇压等6项作业,既可降低作业成本,又有利于农业的可持续性发展。     

高垄平台联合作业机的研究设计

“高垄平台”耕法是治理低湿易涝地的有效手段。为此,给“高垄平台”耕法配套了主要作业机具—播种机,以保障此耕法的顺利实施,保障低湿易涝地丰产丰收。对机器的总体配置和关键部件进行具体设计和试验。经过3年试验表明,该机器增产效果明显,具有很好的推广前景。     

保护性耕作在三江平原的应用研究

保护性耕作是相对于传统耕作的一种新的耕作技术,是以作物秸秆还田和免耕,少耕技术相结合来进行农业生产的。为此,阐述了保护性耕作的实质及关键技术组成,并结合三江平原农业生产现状分析了实施保护性耕作的可行性,同时介绍了三江平原实施保护性耕作的应用情况。