共查询到20条相似文献，搜索用时 31 毫秒
1.
David H. Potten 《Computers and Electronics in Agriculture》1985,1(1):111-118
Since 1980 there has been huge growth in the commercial use of computers in relation to daily farming activities in the U.K. Three main types of application are involved, Bureau services, stand-alone computers on the farm, and on-line services such as Prestel Farmlink through the farmer's television set.Over 120 companies offer computer services to farmers, and 88 were surveyed for this study. Between them they offered 253 different packages of which the most common are for dairy and pig herd management, financial management, arable crops management and other livestock applications.There are no hard data on the number of farmers who use computers, but the proportion is greater than in most other countries. At present at least a third of the companies in the sector have formed joint ventures to market existing packages or develop new applications, and the recent rapid pace of change in the sector is expected to continue. 相似文献
2.
Multiprocessors built from today's microprocessors are economically attractive. Although we can use these multiprocessors for time-sharing applications, it would be preferable to use them as true parallel processors. One key to achieving efficient parallel processing is to match the communications capabilities of the multiprocessor to the communications needs of the problem. The other key is improved parallel programming systems. If these are achieved, then efficient parallel processing can be approached from both ends by providing more communications capability in the hardware and restructuring the problem to reduce the communications requirements. 相似文献
3.
耕地面积测量是农业建设最基本的测量工作之一,在农村土地规划、土地利用、土地调查、土地资源开发等领域有着广泛的应用。结合测量高新技术的应用,对面积测量的方法进行了一些新的探索,并进行了相应的精度分析,供土地测量工作者参考。 相似文献
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尿素在土壤中的水解速率主要受土壤脲酶活性的影响。当前控制尿素水解转化的有效技术措施有添加脲酶抑制剂、硝化抑制剂、尿素包膜以及表面膜技术的应用等。笔者从尿素包膜技术应用及在夏玉米上的施用等方面探讨提高尿素氮利用率的途径。 相似文献
6.
Chenghai YANG 《农业科学与工程前沿(英文版)》2018,5(4):393
The central concept of precision agriculture is to manage within-field soil and crop growth variability for more efficient use of farming inputs. Remote sensing has been an integral part of precision agriculture since the farming technology started developing in the mid to late 1980s. Various types of remote sensors carried on ground-based platforms, manned aircraft, satellites, and more recently, unmanned aircraft have been used for precision agriculture applications. Original satellite sensors, such as Landsat and SPOT, have commonly been used for agricultural applications over large geographic areas since the 1970s, but they have limited use for precision agriculture because of their relatively coarse spatial resolution and long revisit time. Recent developments in high resolution satellite sensors have significantly narrowed the gap in spatial resolution between satellite imagery and airborne imagery. Since the first high resolution satellite sensor IKONOS was launched in 1999, numerous commercial high resolution satellite sensors have become available. These imaging sensors not only provide images with high spatial resolution, but can also repeatedly view the same target area. The high revisit frequency and fast data turnaround time, combined with their relatively large aerial coverage, make high resolution satellite sensors attractive for many applications, including precision agriculture. This article will provide an overview of commercially available high resolution satellite sensors that have been used or have potential for precision agriculture. The applications of these sensors for precision agriculture are reviewed and application examples based on the studies conducted by the author and his collaborators are provided to illustrate how high resolution satellite imagery has been used for crop identification, crop yield variability mapping and pest management. Some challenges and future directions on the use of high resolution satellite sensors and other types of remote sensors for precision agriculture are discussed. 相似文献
7.
湖南省农作物化肥使用量零增长行动策略 总被引：7，自引：1，他引：6
立足湖南化肥施用现状,分析了湖南化肥减量增效面临的形势,提出了坚持矿质营养与有机营养并重实现湖南化肥减量增效的基本思路。目前,湖南省农作物生产过程中,存在有施肥观念陈旧,经济环保意识差;单位面积施肥量偏高,化肥利用率较低;施肥结构不合理,有机肥利用率低;土肥水资源不匹配,施肥方式落后等问题。由于过量施肥原因复杂,减肥增效势在必行。湖南通过10年测土配方施肥技术推广,目前已有52个县从2013年开始出现化肥施用总量零增长。大范围定点对比监测结果表明,种植绿肥、秸秆还田不仅可以改良耕作土壤,而且平均调减氮肥用量10%以上,增产4.24%-6.69%。因此,提出了精准施肥、调优结构、有机肥替代、地力提升、技术集成和示范带动实现湖南化肥减量增效的技术路径。结合湖南实际,具体体现为深入开展测土配方施肥、恢复绿肥种植、普及秸秆还田、推广水肥一体化、推进畜禽粪便资源化利用、推进高标准农田建设等6项关健技术措施,研究制定了到2020年湖南省农作物化肥使用量总体实现负增长的行动目标,其中湘江流域和洞庭湖区率先实现零增长,湘西地区缓增长,其它地区零增长。阐明了加强组织领导、强化科技支撑、增加经费投入、完善扶持政策等4个方面的保障措施。 相似文献
8.
信息技术的发展推动了旅游业与互联网的深度融合，近年来，移动端旅游APP受众广泛，但客户流失率高。基于消费者感知视角，将旅游APP用户群作为研究对象，构建影响旅游APP持续使用意向的结构方程模型，采用实证分析方法，探究促进和阻碍消费者持续使用旅游APP的影响因素。结果表明：消费者使用旅游APP过程中的感知价值以及信任对其持续使用意向有显著正向影响；在感知价值的四个维度中，功能价值对持续使用意向的影响最为显著、经济价值次之；感知风险对信任和持续使用意向的影响均不显著。 相似文献
9.
生态浮床技术应用研究进展 总被引：19，自引：1，他引：19
近年来,随着工农业的发展,人类对水环境的破坏日益严重,全球出现水资源短缺的现象,如何有效利用水资源及将污废水处理回用已经成为摆在人们面前的头等大事。传统的物理、化学方法虽然理论基础比较扎实,但是在实际应用中出现了不少的问题,如投资大、难操作、产生二次污染等。为了解决这些问题,人们将目光转向了利用高等植物净化污水。生态浮床技术作为其中一种生物处理技术,已经被越来越多地用于治理富营养化水体。生态浮床以其独特的优点,通过植物根系的吸附和吸收作用,富集水中的N、P等元素,降解、富集其他有害无毒污染物,并以收获植物体的形式将其搬离水体,从而达到治理水体的目的,既保护了水生态环境,又带来了一定的经济效益。 相似文献
10.
生态浮床技术应用研究进展 总被引：1，自引：0，他引：1
近年来,随着工农业的发展,人类对水环境的破坏日益严重,全球出现水资源短缺的现象,如何有效利用水资源及将污废水处理回用已经成为摆在人们面前的头等大事.传统的物理、化学方法虽然理论基础比较扎实,但是在实际应用中出现了不少的问题,如投资大、难操作、产生二次污染等.为了解决这些问题,人们将目光转向了利用高等植物净化污水.生态浮床技术作为其中一种生物处理技术,已经被越来越多地用于治理富营养化水体.生态浮床以其独特的优点,通过植物根系的吸附和吸收作用,富集水中的N、P等元素,降解、富集其他有害无毒污染物,并以收获植物体的形式将其搬离水体,从而达到治理水体的目的,既保护了水生态环境,又带来了一定的经济效益. 相似文献
11.
Schnur JM 《Science (New York, N.Y.)》1993,262(5140):1669-1676
The use of molecular self-assembly to fabricate microstructures suitable for advanced material development is described. Templating techniques that transform biomolecular self-assemblies into rugged and stable nano- and microstructures are described. By using a lipid-based microcylinder (tubule) as a paradigm, the path followed from research and development to emerging technological applications is detailed. This process includes modification of the lipid molecular structure, the formation and subsequent characterization of cylindrical microstructures, the use of these structures as templates for metallization, and the characterization and assessment of these hollow metal microcylinders for several potential applications. 相似文献
12.
Analyses of the economics of solar collection in the firm- and shifting-peak cases (that is, with off-peak electricity indefinitely available or with a flat load curve) indicate that, for many important applications, solar energy systems that interface with electric utilities can be justified only in terms of the value of the off-peak utility fuels that they displace. In regions where off-peak electricity costs are low, the most economically efficient solar energy systems will be those that use electricity as the auxiliary energy source. This implies extremely low break-even costs for a number of important solar energy applications. In regions where the cost of off-peak electricity is higher than that of competing energy forms, the most economical solar energy systems will utilize auxiliary fuels other than electricity. The general conclusion is that conventional electric utility systems and most solar energy systems represent a poor technological match. The basic problem is that both technologies are very capital intensive. The electric utility, because of the high fixed costs of generation, transmission, and distribution capacity, represents a poor backup for solar energy systems. On the other hand, the solar collection system, because it represents pure, high-cost capital and because of its outage problems, cannot be considered as a part-load source of auxiliary energy for the electric utility system. 相似文献
13.
Henning W Bell WA Billquist PJ Glagola BG Kutschera W Liu Z Lucas HF Paul M Rehm KE Yntema JL 《Science (New York, N.Y.)》1987,236(4802):725-727
Calcium-41 has been suggested as a new tool for radiometric dating in the range of 10(5) to 10(6) years. The concentration of cosmogenic calcium-41 in natural samples of terrestrial origin has now been determined by high-sensitivity accelerator mass spectrometry after pre-enrichment in calcium-41 with an isotope separator. Ratios of calcium-41 to total calcium between 2 x 10(-14) and 3 x 10(-15) were measured for samples of contemporary bovine bone and from limestone deposits. Some prospects for the use of calcium-41 for dating Middle and Late Pleistocene bone and for other geophysical applications are discussed. 相似文献
14.
A user-friendly computerized agricultural herbicide decision model has been developed for selecting profitable site-specific herbicide applications in winter wheat. The model is based on 6 years of field research in southeastern Washington State, USA. The model calibrates herbicide applications to management unit weed densities, soil organic matter, soil moisture, and preceding management, as well as to expected input and output prices. The model increased broadleaf herbicide rates by an average 0.65 of label rates compared to the recommendations by farmers and weed science professionals, but cut the more expensive grass herbicides by an average 0.56 of label rates. The model increased average projected profitability, excluding model application costs, by 65% compared to four other criteria for determining application rates. The profitability increase relative to local farmers was 19%. Both the model and the cooperating farmers properly chose to use no grass herbicides on the study sites, but the weed science experts chose to use up to 1.0 of label rates. The estimated payoff from using the model substantially exceeded the cost of weed scouting and other information collection. Determining economically optimal sampling and management units is an important challenge for the adoption of precision agriculture models like the one developed in this study. 相似文献
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JR Sheats H Antoniadis M Hueschen W Leonard J Miller R Moon D Roitman A Stocking 《Science (New York, N.Y.)》1996,273(5277):884-888
Electroluminescence from organic materials has the potential to enable low-cost, full-color flat-panel displays, as well as other emissive products. Some materials have now demonstrated adequate efficiencies (1 to 15 lumens/watt) and lifetimes (>5000 hours) for practical use; however, the factors that govern lifetime remain poorly understood. This article provides a brief review of device principles and applications requirements and focuses on the understanding of reliability issues. 相似文献
17.
综述无线传感器网络技术在节点构成、网络拓扑、通信协议等方面的特点,重点介绍无线传感器网络技术在精细农业中的典型应用,认为无线传感器网络技术应用于精细农业,需解决信号传输与衰减方式建模、多通信网融合及降低传感器成本等关键问题.提出将无线传感器网络技术与农艺技术、农业机械化及自动化技术等相结合,有助于优化农业决策支持系统,... 相似文献
18.
We believe that methanol is the most versatile synthetic fuel available and its use could stretch or eventually substitute for, the disappearing reserves of low-cost petroleum resources. Methanol could be used now as a means for marketing economically the natural gas that is otherwise going to waste in remote locations. If methanol were used as an additive to gasoline at a rate of 5 to 15 percent, for use in internal combustion engines, there would be an immediate reduction in atmospheric pollution, there would be less need for lead in fuel, and automobile performance would be improved. With increasing production of fuel-grade methanol from coal and other sources, we foresee the increasing use of methanol for electrical power plants, for heating, and for other fuel applications. We hope that a practical methanol fuel cell will be commercially available by the time that methanol becomes plentiful for fuel purposes. Methanol offers a particularly attractive form of solar-energy conservation, since agricultural and forest waste products can be used as the starting material. Indeed, at 1 percent conversion efficiency the forest lands could supply the entire present energy requirements of the United States. 相似文献
19.
农作物秸秆利用技术现状及发展对策 总被引：2，自引：0，他引：2
农作物秸秆作为一种重要的可再生生物质资源,它的合理开发利用越来越受到人们的关注。介绍了秸秆综合利用的现状,包括还田技术、能源化技术、饲料化技术和工业应用技术等。这些技术虽然均能够在一定程度上将秸秆资源化利用,但在实际应用中仍存在一些不足。因此,进一步开发秸秆综合利用新技术,实现秸秆利用的资源化、高效化和产业化是发展的必然趋势。 相似文献
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农业化学化技术对粮食增产,培养地力、改善农产品品质、降低病虫草害的损失等方面具有积极作用,但由于不合理使用簪原因,化肥、农药、农膜等农用物质时生态环境资源带来一些负面影响。介绍了集约制条件下农业化学化技术的应用,分析其对生态环境资源的影响。 相似文献