共查询到20条相似文献，搜索用时 15 毫秒
1.
《Agricultural Systems》2002,71(1-2):41-57
Smallholder crop–animal systems predominate in south Asia, and most of the projected future demands for ruminant meat and milk are expected to be met from the improved productivity of livestock in these mixed farming systems. Despite their importance in the sub-region, there is a paucity of information on research that incorporates animals interactively with cropping. Livestock research has tended to highlight component technologies, often treating diverse and complex mixed farming operations as a single system. Furthermore, little attention has been paid to social, economic or policy issues. Thus, many of the technological interventions have either failed to become adopted at farm level or their uptake has proved unsustainable. This paper reviews aspects of animal production in South Asia; the trends and forecasts for animal populations and products, constraints to productivity, research opportunities and some key examples of technologies that have failed to achieve their full potential on farm. A systems analysis of small-scale crop–livestock operations is advocated, as a precursor for targeting appropriate interventions at farm level to increase animal productivity and protect the natural resources base. 相似文献
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价值链理论为我们科学地分析企业的成本动因、降低企业成本、提升企业的核心竞争力提供了有力的依据和分析方法。本文简要介绍了价值链的概念及分类,分析了我国农机企业实行基于价值链的成本管理的重要性,给出了企业内部价值链优化模型,提出了具体的实施步骤及实施过程中应注意的事项。 相似文献
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《Journal of Agricultural Engineering Research》1997,66(3):203-212
Xray imaging is a well established technique of detecting strongly attenuating materials and has been applied to a number of inspection applications within the agricultural and food industries. However, there are still areas within these industries in which the technique has been underexploited. In particular there are many applications within the biological sciences where we wish to detect weakly attenuating materials against a similar background material. It is in this area that Xray inspection techniques need to be developed. This paper seeks to show how transmission imaging could be better exploited. In particular it is shown that the image contrast between softly attenuating materials can be enhanced by optimally selecting the Xray energy and improving the spatial resolution. The paper also presents full three dimensional reconstructions of samples obtained using computer tomography (CT) techniques and discusses the potential of these methods. 相似文献
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挤压技术加工膳食纤维的研究进展 总被引：4，自引：0，他引：4
膳食纤维对人体健康具有重要的作用，挤压加工膳食纤维具有突出的优点。为此，阐述了膳食纤维在挤压过程中的变化机理，介绍了挤压加工膳食纤维的研究进展，并对其发展前景进行了展望。 相似文献
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Potential, spatial distribution and economic performance of regional biomass chains: The North of the Netherlands as example 总被引：1，自引：0，他引：1
F. van der Hilst V. Dornburg B. Elbersen W.C. Turkenburg J.M.C. van Dam 《Agricultural Systems》2010,103(7):403-4480
This work assesses the viability of regional biomass chains by comparing the economic performance of potential bioenergy crops with the performance of current agricultural land uses. The biomass chains assessed are ethanol production from Miscanthus and from sugar beet in the North of the Netherlands. The competitiveness of bioenergy crops is assessed by comparing the Net Present Value (NPV) of perennial crops, current rotations, and rotation schemes which include additional years of sugar beet. The current land use and soil suitability for present and bioenergy crops are mapped using a geographical information system (GIS) and the spatial distribution of economic profitability is used to indicate where land use change is most likely to occur. Bioethanol production costs are then compared with petrol costs. The productions costs comprise costs associated with cultivation, harvest, transport and conversion to ethanol. The NPVs and cost of feedstock production are calculated for seven soil suitability classes. The results show that bioenergy crops are not competitive with current cropping systems on soils classed as “suitable”. On less suitable soils, the return on intensively managed crops is low and perennial crops achieve better NPVs than common rotations. Our results showed that minimum feedstock production costs are 5.4 €/GJ for Miscanthus and 9.7 €/GJ for sugar beet depending on soil suitability. Ethanol from Miscanthus (24 €/GJ) is a better option than ethanol from sugar beet (27 €/GJ) in terms of costs. The cost of bioethanol production from domestically cultivated crops is not competitive with petrol (12.34 €/GJ) production under current circumstances. We propose that the method demonstrated in this study, provides a generic approach for identifying viable locations for bioenergy crop production based on soil properties and current land use. 相似文献
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Advances in farming systems analysis and intervention 总被引：1，自引：0，他引：1
In this paper, we recognize two key components of farming systems, namely the bio-physical ‘Production System’ of crops, pastures, animals, soil and climate, together with certain physical inputs and outputs, and the ‘Management System’, made up of people, values, goals, knowledge, resources, monitoring opportunities, and decision making. Utilising upon these constructs, we review six types of farming systems analysis and intervention that have evolved over the last 40 years, namely: (1) economic decision analysis based on production functions, (2) dynamic simulation of production processes, (3) economic decision analysis linked to biophysical simulation, (4) decision support systems, (5) expert systems, and (6) simulation-aided discussions about management in an action research paradigm. Biophysical simulation modelling features prominently in this list of approaches and considerable progress has been made in both the scope and predictive power of the modelling tools. We illustrate some more recent advances in increasing model comprehensiveness in simulating farm production systems via reference to our own group's work with the Agricultural Production Systems Simulator (APSIM). Two case studies are discussed, one with broad-scale commercial agriculture in north-eastern Australia and the other with resource poor smallholder farmers in Africa. We conclude by considering future directions for systems analysis efforts directed at farming systems. We see the major challenges and opportunities lying at the interface of ‘hard’, scientific approaches to the analysis of biophysical systems and ‘soft’, approaches to intervention in social management systems. 相似文献
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将区域产业节水的综合效应分解为产业结构调整、产业用水效率变化及两者的交互作用,产业节水具有层次性和时段尺度性特点。通过对浙江省近10年来的产业节水效应进行分析,在不同的时段尺度上,产业用水效率变化产生的节水效应高于产业结构调整,而交互节水效应的时段性表现更为明显。在三次产业层面上,第三产业节水效应不明显;第一、二产业用水效率的提高及第一产业结构比重的降低成为节水效应的主导方面。在各产业内部节水效应上,第一产业的农业部门和第二产业的工业部门用水效率的提高起主导作用。综合分析表明产业用水效率的提高成为浙江省近10年来节水的最主要驱动力。 相似文献
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Annemarie Breukers Dirk L. Kettenis Monique Mourits Wopke van der Werf Alfons Oude Lansink 《Agricultural Systems》2006,90(1-3):112-131
Spread of plant disease in production chains of planting material is a process of great economic importance, but has received little attention from plant disease epidemiologists. Disease control in production chains is therefore often based on rules of thumb and expert judgement by regulatory bodies, rather than on an explicit analysis and evaluation of the epidemiological and economic consequences of alternative strategies. This paper puts forward the idea that individual-based models may be used as a framework to simulate the spread of disease-causing organisms in plant production chains. The “individuals” in this context are the trading units (e.g., batches, lots) of a production chain. The quarantine disease “potato brown rot”, caused by the bacterium Ralstonia solanacearum, is used as an illustrative example. The model simulates the spread of potato brown rot over all potato growing farms and fields in the Netherlands over a chosen time frame. It addresses the relevant infection pathways for this disease in potato production and is spatially explicit.
Model outputs of simulations based on the control strategy as applied in the Netherlands until 2004 are presented. The effects of minor adjustments to this strategy are investigated. The simulations show an irregular pattern of brown rot dynamics in the potato production chain, as is observed in practice. Simulations quantify the relative importance of different infection pathways, and elucidate the effect of testing frequency on these pathways and on the over-all brown rot incidence. The study shows that individual-based modelling (IBM) provides a powerful platform for modelling the epidemiology and impact of diseases in plant production chains. IBM can be effectively used for the analysis, evaluation and design of cost-effective disease management policies. 相似文献
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Mike Bonell 《Irrigation and Drainage Systems》2010,24(3-4):279-325
Within the framework of IWRM, a major concern in the humid tropics is the effects of ‘global warming’ on the storm rainfall-runoff hydrology of both forests and converted forest lands. Further how such effects need to be incorporated within adaptive, forest-water-land management. But since the mid- 20th century, dramatic changes in land- use (LU) and land cover (LC) have also occurred which have led to rapid rates of deforestation and an expansion of land—forest degradation. How much these man-induced impacts have been influential on climate –water relations, as against the effects of inherent climate variability and predicted climate change scenarios, still remains a major challenge to quantify. Thus embedded within the global warming issue are these additional LU/LC change impacts on climate-rainfall-storm runoff across scales which also require consideration under the broader mandate of ‘global change’. The work will initially succinctly summarize the existing uncertainties linked with both Global Climate Models (GCMs). Subsequently more detailed attention will be given to uncertainties linked with LC/LU change. The experiences of hurricane Mitch in Central America will then set the scene for an alternative strategy. A principle message is a call for more concentrated research effort on geographically the outer margins of the ‘maritime continent’ (centred on the Indonesian Archipelago) in the Western Pacific where tropical cyclone frequency is very high. This region presents a diversity of socio-economies and an opportunity to produce adapted forest-land management measures in preparation for future global change (warming and anthropogenic). Such measures can then be extrapolated to currently less frequently, affected areas from extreme events like hurricane Mitch. Examples from research in the tropical- cyclone prone, “Wet Tropics” of northeast Australia linked with the management of tropical rainforests and the adjoining sugar cane lands are then used to demonstrate these opportunities. 相似文献
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《Agricultural Systems》2003,76(2):623-638
Efficient production of sugar from sugarcane requires integration of growing, harvesting, transport, milling, and marketing. While research targeted to each of these sectors has added significant value in the past, further gains are limited, giving rise to an increasing focus on whole of systems research for the industry to maintain its international competitiveness. A major whole of industry issue is the need to take advantage of geographical, temporal, and crop characteristic differences in sugar yields. Through capturing most of this variability, a methodology was developed that allowed the assessment of profitability benefits from alternative harvest date of cane options throughout a mill region. This resulted in an original application of operations research. Options analyses were carried out in partnership with mill regions throughout the Australian sugar industry, showing potential gains of up to A$157/ha at a sugar price of A$250/t, with the size of the gains dependent on the international sugar price and climatic variability. 相似文献
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依据休闲农业与乡村旅游两大产业耦合协调机理,以长三角地区为例,选取2014—2020年相应指标构建休闲农业和乡村旅游产业发展评价指标体系,利用熵值法和耦合协调度模型对二者耦合协调度做出实证研究。实证研究表明：2014—2019年长三角地区休闲农业和乡村旅游产业耦合协调度整体呈现平稳上升态势,产业融合水平整体向好,其中江苏省休闲农业与乡村旅游产业耦合度从2014年的0.595 7上升至2019年的0.972 5,整体呈现增长态势;安徽省两大产业耦合度出现较小的波动,最低值为2018年的0.868 9,最高则出现在2019年,值为0.987 3;浙江则不同于江皖两省,2014年就呈现出高度的产业耦合水平,并在研究期内一直保持高水平发展。因此,从产业耦合度的角度而言,浙江>安徽>江苏。同时,江苏和安徽从开始的乡村旅游主导型逐渐发展为休闲农业主导型,而浙江则两产业发展水平交替领先,且发展水平差值在三省当中最小,可见浙江的两大产业相互支撑、相互促进作用显著。此外,通过耦合结果发现疫情对农旅融合具有一定的负面影响。 相似文献
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摘要：以钻石模型理论为基础,借助FD（Forced Decision）强制评价法,对陕西省澄城樱桃品牌价值进行评价。得出结论：需求条件、产业集群、机遇三个因素的价值系数小于1,这三个方面应作为澄城樱桃未来产业发展过程中重点关注和改进的领域;而生产要素、企业战略结构与同业竞争、政府三个因素的价值系数大于1,说明当前澄城樱桃产业发展在这三个方面的投入产出值较高,对于澄城樱桃品牌价值的提升作用较大,未来还应加大这三个方面的输入值,使得澄城樱桃产业得到最快、最有效的品牌价值提升。 相似文献
13.
通过有限元法理论计算，光弹试验和成组疲劳试验，深入系统地研究了滚子链链板有效应力集中系分布问题。该研究结果，可作为滚链子链疲劳可靠性设计的重要基础资料。 相似文献
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《Agricultural Water Management》2005,73(2):113-130
The information provided in publications on water-related agronomic trials and irrigation interventions is often too limited to compare values of water productivity (WP), i.e. the ratio between produced plant biomass and the amount of water used for that production, from different years, regions, etc. in a meaningful way. In this article, we show with the help of simulation models how WP-values are affected by different definitions of the numerator and denominator, environmental circumstances, such as climate, year and sowing date, and crop characteristics. In many cases, this resulted in 10–25% change in the WP-values, and sometimes even more. A minimum dataset is formulated that will make normalization and comparison of different WP-values easier. Most of these data are known by those who execute experiments, and we recommend strongly that these are reported in the future. Simulation models are excellent tools to explore the limitations and opportunities for increasing WP, provided they are well calibrated and validated for biomass, soil water availability, and ET. Such a balanced estimation of the “crop” and the “drop” requires an improved cooperation between hydrologists and agronomists. Comparison of actual WP(E)T and simulated maximum WP(E)T for the same environmental conditions does show the scope for increasing WP(E)T and other WP-values. Since WP-values are ratios, the production level on a hectare basis should be given besides WP. When we try to find an optimum combination of production per hectare and production per m3 irrigation water, we will be able to produce “more food with less water”. 相似文献
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目前,黑龙江省林业已逐步形成了一二三产业竞相发展的、比较完整的林业产业体系,但黑龙江省林业的产业价值链中存在着第一产业中的森林资源培育不足和林产品加工业增值幅度低等问题。为此,从林业产业的内涵出发,分析了黑龙江省林业产业发展存在的问题,指出了发展黑龙江省林业产业的重点,并提出了加强黑龙江省林业产业建设的对策。 相似文献
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Luiz A. Martinelli Rachael GarrettSilvio Ferraz Rosamond Naylor 《Agricultural Systems》2011,104(5):419-428
Sugar and ethanol production are key components of Brazil’s rural development and energy strategies, yet in recent years sugar production has been widely criticized for its environmental and labor practices. This study examines the relationship between rural development and sugarcane, ethanol, and cattle production in the state of São Paulo. Our results suggest that the value added components of sugarcane production, which include sugar refining and ethanol production, may have a strong positive affect on local human development in comparison to primary agricultural production activities and other land uses. These results imply that sugar production, when accompanied by a local processing industry can stimulate rural development. However, this paper also highlights the significant environmental and social harms generated by the sugar industry at large, which may undermine its development benefits if not addressed. 相似文献