检索结果-南通市图书馆

Development of a PWM Precision Spraying Controller for Unmanned Aerial Vehicles

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2010年第3期7卷 276-283页

作者： W.Clint Hoffmann Brad Fritz usda-ARS College Station

This paper presents a new Pulse Width Modulation (PWM) controller for Unmanned Aerial Vehicle (UAV) precisionsprayer for agriculture using a TL494 fixed-frequency pulse width modulator together with a data acquisition board and developedsoftware. An UAV can be remotely controlled or flown autonomously by pre-programmed flight plans. The PWMcontroller was implemented through the guidance system on the UAV with control commands sent between the UAV helicopterand the ground control station via a wireless telemetry system. The PWM controller was tested and validated using LabVIEW8.2. Several analyses were performed in a laboratory to test different control signals. The results show that the PWM controllerhas promise as a higher precision technique for spray applications, which will improve efficiency of pesticide application,especially in crop production areas.

关键词： PWM controller TL494 precision spraying UAV

Forest biodiversity, relationships to structural and functional attributes, and stability in New England forests

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2018年第2期5卷 177-188页

作者： Yude Pan Kevin McCullough David Y. Hollinger usda Forest Service Durham NH USA usda Forest Service Madison WI USA

Background： Forest biodiversity is the foundation of many ecosystem services, and the effect of biodiversity on ecosystem functioning and processes （BEF） has been a central issue in biodiversity studies. Although many hypotheses have been developed to interpret global gradients of biodiversity, there has not been complete agreement on mechanisms controlling biodiversity patterns and distributions. Differences may be due to limited observation data and inconsistencies of spatial scales in analysis. Methods： In this study, we take advantage of usda Forest Service forest inventory and analysis （FIA） data for exploring regional forest biodiversity and BEF in New England forests. The FIA data provide detailed information of sampled plots and trees for the region, including 6000 FIA plots and more than 33,000 individual trees. Biodiversity models were used to analyze the data. Results： Tree species diversity increases from the north to the south at a rate about 2-3 species per latitudinal degree. Tree species diversity is better predicted by tree height than forest age or biomass. Very different distribution patterns of two common maple species, sugar maple （Acer sdcchorum） and red maple （Acer rubrum）, highlight the vulnerability of sugar maple and its potential replacement by red maple on New England landscapes. Red maple generally already outperforms sugar maple, and will likely and continuously benefit from a changing climate in New England. Conclusions： We conclude that forest structure （height） and resources （biomass） are more likely foundational characteristics supporting biodiversity rather than biodiversity determining forest productivity and/or biomass. The potential replacement of red maple for sugar maple in the New England areas could affect biodiversity and stability of forest ecosystem functioning because sugar maple plays important ecological roles distinct from red maple that are beneficial to other tree species in northern hardwood forests. Such a change

关键词： Forest biodiversity Biodiversity effect on function (BEF) New England Forest inventory data Species diversity Latitudinal diversity gradient Forest stability of ecosystem functioning Forest resilience Sugar maple Red maple Changing climate

Regulation of cytokine gene expression by orosomucoid in neonatal swine adipose tissue

在线全文

学校读者我要写书评

暂无评论

Journal of Animal Science and Biotechnology 2016年第3期7卷 403-411页

作者： Timothy G.Ramsay Margo J.Stoll Le Ann Blomberg Thomas J.Caperna Animal Biosciences and Biotechnology Laboratory USDA/ARSBeltsville Agricultural Research CenterUSDABeltsvilieMD 20705USA

Background： Porcine adipose tissue expresses orosomucoid（ORM1） mRNA, a protein with anti-inflammatory and immunomodulatory properties. Previous research has demonstrated that porcine ORM1 can reduce insulin stimulated glucose metabolism in porcine adipose tissue in vitro. The present study was designed to examine the preweaning ontogeny of ORM1 m RNA abundance in porcine subcutaneous adipose and to determine if ORM1 can regulate m RNA abundance of inflammatory cytokines that contribute to insulin resistance in primary cultures derived from neonatal porcine subcutaneous adipose tissue. Cultures were differentiated in vitro and subsequently the adipocyte containing cultures were incubated for 24 h with 0–5000 ng porcine ORM1/m L medium. Cultures were then harvested, total RNA extracted for use in reverse transcription and the m RNA abundance of cytokine m RNA quantified by real-time ***： ORM1 m RNA abundance within neonatal adipose tissue does not change from d 1 to d 21 of age and is a very small fraction relative to liver m RNA abundance. The ORM1 m RNA level in porcine adipocytes and stromalvascular cells are similar（P 〉 0.05）. Treatment with ORM1 did not affect TNFα（tumor necrosis factor α） m RNA level（P 〉 0.05）, while interleukin 6（IL6） m RNA abundance was reduced 32 % at 1,000 ng ORM1/m L（P 〈 0.01）. However,TNFα protein content in the cell culture media was reduced by ORM1 treatment（5,000 ng/m L, P 〈 0.05）, whereas ORM1 had no detectable effect on the media content of IL6（P 〉 0.05）. The reduction of macrophage migration inhibitory factor（MIF） m RNA abundance by ORM1 was dose dependent（P 〈 0.01）. Monocyte chemotactic protein（MCP） m RNA level was reduced 27 % by 1,000 ng ORM1/m L（P 〈 0.05）.Conclusions： The data suggest that ORM1 has limited effects TNFα, IL6, MIF or MCP expression at the concentrations tested. Secondly, these cytokines do not appear to contribute to the reported insulin resistance induced by ORM1 in porcine adipose tissue in vitro as an in

关键词： Adipose Cytokines Neonate Orosomucoid Swine

Mineral concentrations of chickpea and lentil cultivars and breeding lines grown in the *** Northwest

在线全文

学校读者我要写书评

暂无评论

The Crop Journal 2018年第3期6卷 253-262页

作者： George J.VANDemark Michael A.Grusak Rebecca J.Mc Gee usda-ARS Grain Legume Genetics and Physiology Research Unit usda-ARS Red River Valley Agricultural Research Center

Diseases and health complications caused by mineral deficiencies afflict billions of people globally. Developing pulse crops with elevated seed mineral concentrations can contribute to reducing the incidence of these deficiencies. The objectives of this study were to estimate variance components conditioning seed mineral concentrations of chickpea and lentil grown in Washington and Idaho, determine correlations between different mineral concentrations and between mineral concentrations and yield, 100-seed weight, and days to flowering, and compare seed mineral concentrations between chickpeas and lentils grown in adjacent plots. Genotype effects, although significant in chickpea and lentil for all minerals except selenium, tended to be minimal compared to location, year, and their interaction effects. In both chickpeas and lentils high positive correlations were observed between seed concentrations of phosphorus and potassium, phosphorus and zinc, and potassium and zinc. Correlations between mineral concentration and yield, and mineral concentration and days to 50% flowering were similar for chickpeas and lentils across the majority of minerals. These results may reflect similarities between the two crops in physiological processes for mineral uptake and partitioning. Lentils had higher concentrations of iron and zinc than chickpea when the two crops were grown in adjacent plots,whereas chickpeas had higher concentrations of calcium and manganese. Plant genotypes that are more efficient at obtaining minerals from growing environments will be useful as parental materials to develop improved chickpea and lentil cultivars that have good yield potential coupled with high seed mineral concentrations.

关键词： Chickpea Lentil Mineral Nutrition Pulse

Predicting Ailanthus altissima presence across a managed forest landscape in southeast Ohio

在线全文

学校读者我要写书评

暂无评论

Forest Ecosystems 2019年第4期6卷 261-273页

作者： Louis R.Iverson Joanne Rebbeck Matthew P.Peters Todd Hutchinson Timothy Fox Northern Research Station USDA Forest Service

Background: The negative impacts of the exotic tree, Ailanthus altissima(tree-of-heaven, stink tree), is spreading throughout much of the Eastern United States. When forests are disturbed, it can invade and expand quickly if seed sources are ***: We conducted studies at the highly dissected Tar Hollow State Forest(THSF) in southeastern Ohio USA,where Ailanthus is widely distributed within the forest, harvests have been ongoing for decades, and prescribed fire had been applied to about a quarter of the study area. Our intention was to develop models to evaluate the relationship of Ailanthus presence to prescribed fire, harvesting activity, and other landscape characteristics, using this Ohio location as a case study. Field assessments of the demography of Ailanthus and other stand attributes(e.g., fire, harvesting, stand structure) were conducted on 267 sample plots on a 400-m grid throughout THSF,supplemented by identification of Ailanthus seed-sources via digital aerial sketch mapping during the dormant season. Statistical modeling tools Random Forest(RF), Classification and Regression Trees(CART), and Maxent were used to assess relationships among attributes, then model habitats suitable for Ailanthus ***: In all, 41 variables were considered in the models, including variables related to management activities, soil characteristics, topography, and vegetation structure(derived from LiDAR). The most important predictor of Ailanthus presence was some measure of recent timber harvest, either mapped harvest history(CART) or LiDARderived canopy height(Maxent). Importantly, neither prescribed fire or soil variables appeared as important predictors of Ailanthus presence or absence in any of the models of the ***: These modeling techniques provide tools and methodologies for assessing landscapes for Ailanthus invasion, as well as those areas with higher potentials for invasion should seed sources become available. Though a case study on

关键词： Ohio Random Forest CART Maxent Landscape model Non-native invasive species

Simulation of Landscape Pattern of Old Growth Forests of Korean Pine By Block Kriging

在线全文

学校读者我要写书评

暂无评论

Journal of Forestry Research 1997年第3期8卷 131-136页

作者：王政权张颜东王庆成 HarbinLi usda.SouthernForestResearchStation

The study area was located in Liangshui Natural Reserve. Xaoxing'an Mountains. Northeastern China. Korean pine forests are the typical forest ecosystems and landscapcs in this region. It is a high degrees of spatial and temporal hetcrogeneity at different scales, which effected on landscape pattern and processes. In this paper we used the data of 144 plots and semivariogram to analyze spatial heterogeneity of old growth forests of Korean pine in landscape level. Model for forest variations by isotropic semivariogram is linear with sill. The spatial heterogeneity is dependent on scales and dircctions in Korean pine forests. Patterns of forest types in space were resulted from complex interactions between physical and biological forces. We uscd 20 metres for interpolation interval to cstimate the values of unsampled area. Comparing the results with field data, block kriging and mapping are an cffective techniques to simulate landscape pattern.

关键词： Korean pine Semivariogram Block kriging Simulation Landscape pattern

Resistance risk assessment of six pyrethroids and acephate toward the resistant adult tarnished plant bug,Lygus lineolaris

在线全文

学校读者我要写书评

暂无评论

Insect Science 2024年第3期31卷 792-802页

作者： Yuzhe Du Shane Scheibener Yucheng Zhu Maribel Portilla Mingling Zhang usda-ARS Southern Insect Management Research UnitStonevilleUSA usda-ARS Pollinator Health in Southern Crop Ecosystem Research UnitStonevilleUSA

Due to rapidly developed resistance,pest management relies less on pyrethroids to control economically damaging infestations of the tarnished plant bug(TPB),Lygus lineolaris(Palisot de Beauvois)in cotton fields of ***,pyrethroid resistance remains prevalent in TPB *** study assessed the resistance levels in adult TPB to six common pyrethroids and *** TBPs were collected from wild host plants in late October after harvest in the Mississippi Delta region of the United *** on LCso values,the field-resistant TPBs displayed higher resistance to permethrin,esfenvalerate,and bifenthrin(approximately 30 fold)and moderate resistance toα-cyhalothrin,β-cyfluthrin,5-cypermethrin,and acephate(approximately 15 fold).Further investigations showed that the inhibitors of three detoxification enzyme,triphenyl phosphate(TPP),diethyl maleate(DEM),and piperonyl butoxide(PBO)had synergistic effects on permethrin,γ-cyhalothrin,and bifenthrin in resistant ***,elevated esterase,GST,and P450 activities were significantly expressed in fieldresistant ***,GST and esterase were reduced after 48 h exposure to certain pyrethroids at LCso *** synergistic and biochemical assays consistently indicated that P450 and esterase were involved in pyrethroid detoxification in *** study provides valuable information for the continued use of pyrethroids and acephate in controlling TPBs in cotton fields in the Mississippi Delta region of the United States.

关键词： cytochrome P450-monooxygenases(P450) detoxification enzyme activities esterase Lygus lineolaris pyrethroids and organophosphate resistance tarnished plant bug

Applied and Environmental Chemistry of Animal Manure:A Review

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Pedosphere 2016年第6期26卷 779-816页

作者： Zhongqi HE Paulo H.PAGLIARI Heidi M.WALDRIP usda-ARS Southern Regional Research Center Department of Soil Waterand ClimateUniversity of MinnesotaSouthwest Research and Outreach Center usda-ARS Conservation and Production Research Laboratory

Animal manure consists of predominantly urine and feces, but also may contain bedding materials, dropped feed, scurf, and other farming wastes. Manure is typically applied to soils as fertilizer for agricultural production. The estimated amount of manure produced in 12 major livestock-producing countries is 9 × 10^9 Mg of manure annually. Manure is rich in plant nutrients. However, manure is also considered as an environmental pollutant when it is over-applied to cropland or following runoff into surface water. Manure can also influence global climate change via emissions of methane （CH4） and nitrous oxide （N2O）. Thus, increased and updated knowledge of applied and environmental chemistry of animal manure is needed to shed light on the research and development of animal manure utilization and minimization of its adverse environmental concerns. The advances in basic and applied studies of manure major components, organic matter, phosphorus, and nitrogen, primarily related to US livestock production are summarized in this review. Detailed focus was placed on three notable challenges for future manure research： 1） soil application of animal manure, 2） manure phytate phosphorus, and 3） manure nitrogen availability. This review may contribute to the global effort in sustainable and environmentally sound agriculture by stimulating new ideas and directions in animal manure research, and promoting application of knowledge and insight derived from manure research into improved manure management strategies.

关键词： environmental pollutant fertilizer nitrogen availability organic matter phosphorus phytate plant nutrients

Effects of silt loading on turbulence and sand transport

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2012年第4期27卷 451-459页

作者： Daniel G.WREN Roger A.KUHNLE usda-Agricultural Research Service-National Sedimentation Laboratory

The transport of bed material and fluid turbulence are affected by many factors,including the fine sediment load being carried in a *** research has focused on sand-sized particles introduced to gravel beds,while the effect of silt load on sand transport has received less attention. Experiments on the effects of silt load,in concentrations 0-26,900 mg l-1,on sand transport were performed with a recirculating laboratory flume using three different sand bed configurations:ripples （Fr=0.24）,dunes（Fr=0.34）,and dunes（Fr=0.48）.Three Acoustic Doppler Velocimeters were arranged to measure flow and turbulence quantities simultaneously in one *** transport did not change in a consistent manner with increasing silt load,increasing up to 4,000 mg l-1for dunes （Fr=0.48） and up to 2,000 mg l-1for dunes（Fr=0.34） and then declining to near the clear water case with increasing silt *** addition for the ripple case caused a relatively small change in sand transport,decreasing with added silt up to approximately 2,000 mg l-1and then increasing as silt went up to approximately 10,000 mg ***（Fr=0.48） decreased in length and height as silt increased,while dunes（Fr=0.34） did not show a consistent trend.A clear trend of decreasing Reynolds stress with increasing silt concentration was observed in the ripple case,with a 33% reduction in near-bed Reynolds stress caused by an 8,900 mg l-1concentration of silt.

关键词： Turbulence modulation Bedforms Dunes Sand transport Silt loading