山地果园钢丝绳牵引货运机超声波避障系统   总被引：8，自引：0，他引：8  

李震  卢加纳  洪添胜  宋淑然  黄家洋  陈辉鑫 《农业机械学报》2011,42(10):116-120

为避免山地果园钢丝绳牵引式货运机运行时碰撞穿越轨道的行人或其他障碍物,提高果园轨道货运系统的安全性和稳定性,开发了山地果园钢丝绳牵引式货运机避障系统,包括STC单片机、超声波测距、红外光电检测、无线通信、语音报警及手动控制等模块.系统设计指标为:障碍物检测距离不小于150 cm,避障成功率达到100％.系统应用试验结果表明:使用静态障碍物,上坡避障完成后货运机前端与障碍物间最小距离为100 cm,下坡避障完成后该间距为90 cm;使用动态障碍物,上坡避障完成后货运机前端与障碍物间最小距离为98 cm,最小延时为0.64 s;下坡避障完成后该间距为66 cm,最小延时为1.30s.  相似文献   

Pesticide and Heavy Metals Residue in Wastewater, Soil and Plants in Wastewater Disposal Site Near Al-Lajoun Valley, Karak / Jordan     

Anwar G. Jiries  Farh M. Al Nasir  Friedrich Beese 《Water, air, and soil pollution》2002,133(1-4):97-107

Disposal of raw wastewater and sludge creates thepotential for pesticides and heavy metal contamination. Afield study was conducted to determine the residueconcentration level of chlorinated pesticides and four heavymetals (Zn, Pb, Cu and Ni) in raw wastewater, soils andplants at Karak raw wastewater disposal site. The resultsindicated that the investigated area was heavily contaminatedwith various types of pesticides. The distribution of different pesticides in soils and wastewater was influencedby the solubility of these pesticides such that the higherthe solubility the more is present in water phase and viceversa. Vinclozoline was the dominant pesticide in most of thesamples. Some pesticides of which application is restrictedto be used in Jordan, such as DDT and its metabolites, weredetected in the investigated area.Heavy metals existed in relatively higher concentrationsin soils than in wastewater, which was due to the high pH ofthe wastewater enhancing its precipitation. Zinc was thehighest among the analyzed heavy metals in both wastewaterand soils.The residue level of both heavy metals and chlorinatedpesticides were highest at the emission source decreasinggradually with distance.  相似文献   

Midwest (U.S.A.) reservoir water quality modification     

Victor I. Okereke  E. Robert Baumann  T. Al Austin  Donna Schulze Lutz 《Water, air, and soil pollution》1988,37(3-4):325-341

The impact of a flood control, low flow argumentation reservoir in the Midwestern part of the United States on BOD, COD, and ammonia was evaluated in this paper. Fifteen years of weekly water quality data (9 yr before impoundment and 6 yr after impoundment) from four sampling stations upstream and downstream of the reservoir were available for analysis. The annual loading rates of these parameters (kg ha^?1 vr^?1) were found to correlate well with annual runoff (cm yr^?1). Besides, the reservoir was found to have had a significant and beneficial impact on the downstream loading rates of BOD and COD, which were reduced by 55 and 75%, respectively. As for ammonia, the results of this study indicate that its annual loadings at downstream locations were not significantly affected by the reservoir. Average non-point source contributions of BOD and ammonia loadings into the system were found to be about 80 and 55%, respectively.  相似文献   

Concentration and deposition of trace metals in Ontario-1982     

Walter H. Chan  Al J. S. Tang  David H. S. Chung  Maris A. Lusis 《Water, air, and soil pollution》1986,29(4):373-389

Results of trace metal concentrations in air and precipitation and the corresponding wet and dry deposition in Ontario in 1982 arc reported. In terms of the spatial patterns, in general, there was a decreasing gradient from south-to-north in both concentration and deposition. Patterns differed with each parameter although certain groups of metals (e.g., Fe and Al; Pb, Zn, and Mn) displayed similar patterns. In general, wet deposition was greater than dry deposition at all sites. Geographically, the variability in the wet to dry deposition ratio for coarse particles (MMD > 2.5 μm) was small. However, it increased from the south to the north for fine particles (MMD < 2.5 μm), being higher away from the source areas. Scavenging ratios (W) have been derived from the precipitation and air concentrations of trace metals. The scatter in W is quite large for all trace metals, up to 2 orders of magnitude. There was little seasonal variability in W for fine particles (Pb, Mn, Zn, and Cd). However, coarse particles (Fe, Al, and Cu) were more efficiently scavenged by snow than by rain.  相似文献   

阴山北麓缓坡丘陵不同植被类型下土壤水分空间分布特征—以武川县为例   总被引：3，自引：0，他引：3  

李晓娜  郑大玮  李忠辉 《土壤通报》2005,36(1):23-25

近年来由于农耕面积的进一步扩大,阴山北麓植被破坏程度加深,水蚀风蚀沙化现象日益严重。本文以内蒙古阴山北麓为研究对象,研究了这一地区缓坡丘陵的土壤水分分布特征及不同植被类型下土壤水分时空分布,为这一地区的生态治理过程中,植被类型、种植模式的选择提供数字依据。结果表明:(1)后山地区与内地相反,缓坡丘陵土壤水分以阳坡为最高,阴坡次之,顶部为最低;(2)该地区的土壤水分分布受植被类型等的影响,表现出一定的空间变异特性。  相似文献   

Usefulness of Stress Indicators in Forecasting Population Trends in Microtus arvalis (Pallas)1     

M. Hamar  Al. Tuta  Anca Petrescu  Liliana Babes 《EPPO Bulletin》1977,7(2):349-357

The appearance of a stress condition in Microtus arvalis (Pallas) populations was established on the basis of histochemical analyses and correlated with population dynamics. It was found that stress appears only during invasions, i.e. when crop damage has already occurred. Commonly, the population crash occurs 30 to 50 days after the appearance of stress. It is concluded that stress indices can neither be used for warnings nor for long-term forecasts of outbreaks.  相似文献   

The high cost of coming to America     

Teich A  White WD 《Science (New York, N.Y.)》2006,312(5774):657

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Glanders--a comprehensive review     

Wittig MB  Wohlsein P  Hagen RM  Al Dahouk S  Tomaso H  Scholz HC  Nikolaou K  Wernery R  Wernery U  Kinne J  Elschner M  Neubauer H 《DTW. Deutsche tier?rztliche Wochenschrift》2006,113(9):323-330

Since 1990 the number of glanders outbreaks in race, military and pleasure horses in Asia and South America is steadily increasing. Glanders, which is eradicated in Western Europe, Australia and Northern America, is currently considered a re-emerging disease. Consequently, the disease may be introduced into glanders-free regions by subclinical carriers at any time. The causative agent of glanders, Burkholderia (B.) mallei, is highly contagious and leads to chronic disease in horses whereas in donkeys and mules the disease is acute and often fatal. Occurrence of the disease leads to international trading restrictions and infected animals immediately have to be culled and safely disposed off. In humans B. mallei infection results in a severe clinical course, and is fatal without appropriate therapy. Its pathogenicity makes B. mallei a potential biological agent that may be used in bioterroristic attacks. Due to the eradication of glanders in the second half of the last century, veterinarians in western European countries are no longer familiar with its clinical presentation in solipeds. Having these facts in mind, this review describes the epidemiology, clinical signs, pathology and the current eradication strategy of this interesting zoonosis. Pictures of imported endurance horses infected with glanders taken during an eradication campaign in Dubai, United Arab Emirates, in 2004 illustrate most typical clinical findings.  相似文献   

Organics captured from comet 81P/Wild 2 by the Stardust spacecraft     

Sandford SA  Aléon J  Alexander CM  Araki T  Bajt S  Baratta GA  Borg J  Bradley JP  Brownlee DE  Brucato JR  Burchell MJ  Busemann H  Butterworth A  Clemett SJ  Cody G  Colangeli L  Cooper G  D'Hendecourt L  Djouadi Z  Dworkin JP  Ferrini G  Fleckenstein H  Flynn GJ  Franchi IA  Fries M  Gilles MK  Glavin DP  Gounelle M  Grossemy F  Jacobsen C  Keller LP  Kilcoyne AL  Leitner J  Matrajt G  Meibom A  Mennella V  Mostefaoui S  Nittler LR  Palumbo ME  Papanastassiou DA  Robert F  Rotundi A  Snead CJ  Spencer MK  Stadermann FJ  Steele A 《Science (New York, N.Y.)》2006,314(5806):1720-1724

Organics found in comet 81P/Wild 2 samples show a heterogeneous and unequilibrated distribution in abundance and composition. Some organics are similar, but not identical, to those in interplanetary dust particles and carbonaceous meteorites. A class of aromatic-poor organic material is also present. The organics are rich in oxygen and nitrogen compared with meteoritic organics. Aromatic compounds are present, but the samples tend to be relatively poorer in aromatics than are meteorites and interplanetary dust particles. The presence of deuterium and nitrogen-15 excesses suggest that some organics have an interstellar/protostellar heritage. Although the variable extent of modification of these materials by impact capture is not yet fully constrained, a diverse suite of organic compounds is present and identifiable within the returned samples.  相似文献   

金钱槭果实化学成分分析     

石亚娜  王跃虎  郭蓉  张金渝  王元忠  金航  龙春林 《云南农业大学学报(自然科学版)》2012,27(4):600-604

 为研究金钱槭果实中的化学成分,利用各种波谱技术从金钱槭果实乙醇提取物中共分离得到4个三萜类成分（1-4）和一个甾体化合物（5）,利用波谱技术及化学方法将它们分别鉴定为高根二醇 (1)、28-羟基-12-齐墩果烯-3-酮 (2)、高根二醇3-O-棕榈酸酯 (3)、羽扇豆烯酮 (4)和豆甾-4-烯-3-酮 (5),所有化合物均首次从该植物中发现。  相似文献