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Direct measurements of the Electron Energy Flux versus Electron Temperature Gradient in Tokamak Discharges

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Plasma Science and Technology 2004年第1期6卷 2130-2134页

作者： K.W.Gentle m.E.Austin P.E.Phillips Fusion research center University of Texas USAFusion Research Center University of Texas USAFusion Research Center University of Texas USA

Electron thermal transport is one of the most complex processes in fusionplasmas. It is generally described by a simple thermal diffusivity in transport analyses ofdischarges, but there is evidence of critical gradient effects with moderate stiffness. By analyzingperiodic perturbations to an equilibrium, one canmeasure the variations in electron energy flux andelectron temperature gradient over the perturbation cycle, obtaining the flux as a function ofgradient over the range of parameters generated by the perturbation. Although time-dependenttransport analysis is very sensitive to noise in the input data, averaging over many cycles of aperiodic perturbation can provide data of sufficient quality. The analyses presented here are basedon the ECE temperature data with high spatial and temporal resolution and full profile coverage onDIII-D for sawteeth and modulated ECH heating.

关键词： tokamak discharges electron energy flux electron temperature gradient direct measurements

multivariate Geostatistical model for Groundwater Constituents in texas

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International Journal of Geosciences 2014年第13期5卷 1609-1617页

作者： Faye Anderson texas A & m agrilife research center at Beaumont College Station Texas USA

Although many studies have explored the quality of texas groundwater, very few have investigated the concurrent distributions of more than one pollutant, which provides insight on the temporal and spatial behavior of constituents within and between aquifers. The purpose of this research is to study the multivariate spatial patterns of seven health-related texas groundwater constituents, which are calcium (Ca), chloride (Cl), nitrate (NO3), sodium (Na), magnesium (mg), sulfate (SO4), and potassium (K). Data is extracted from texas Water Development Board’s database including nine years: 2000 through 2008. A multivariate geostatistical model was developed to examine the interactions between the constituents. The model had seven dependent variables—one for each of the constituents, and five independent variables: altitude, latitude, longitude, major aquifer and water level. Exploratory analyses show that the data has no temporal patterns, but hold spatial patterns as well as intrinsic correlation. The intrinsic correlation allowed for the use of a Kronecker form for the covariance matrix. The model was validated with a split-sample. Estimates of iteratively re-weighted generalized least squares converged after four iterations. matern covariance function estimates are zero nugget, practical range is 44 miles, 0.8340 variance and kappa was fixed at 2. To show that our assumptions are reasonable and the choice of the model is appropriate, we perform residual validation and universal kriging. moreover, prediction maps for the seven constituents are estimated from new locations data. The results point to an alarmingly increasing levels of these constituents’ concentrations, which calls for more intensive monitoring and groundwater management.

关键词： multivariate Geostatistical Groundwater Constituents texas

Effects of environment lighting on the growth,photosynthesis,and quality of hydroponic lettuce in a plant factory

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International Journal of Agricultural and Biological Engineering 2018年第2期11卷 33-40页

作者： Xin Zhang Dongxian He Genhua Niu Zhengnan Yan Jinxiu Song Key Lab of Agricultural Engineering in Structure and Environment of ministry of Agriculture China Agricultural UniversityBeijing 100083China texas A&m agrilife research at El Paso Texas A&M University System1380 A&M CircleEl PasoTX79927USA Beijing research center for Information Technology in Agriculture Beijing 100097China

Leafy vegetable production under controlled environment using artificial lighting has many advantages over conventional greenhouses and open-field ***,high initial investment and operation costs are restricting the wide application of this *** order to design an optimal artificial lighting environment for lettuce production,effects of different combinations of light intensity,photoperiod,and light quality on growth,quality,photosynthesis,and energy use efficiency of lettuce(Lactuca sativa *** Ziwei)were investigated under a closed plant *** transplants were grown under photosynthetic photon flux density(PPFD)at 150μmol/m^(2)·s,200μmol/m^(2)·s,250μmol/m^(2)·s,and 300μmol/m^(2)·s provided by fluorescent lamps(FL)with a red to blue ratio(R:B ratio)of 1.8 and light-emitting diode(LED)lamps with R:B ratio of 1.2 and 2.2,in combination with photoperiod of 12 and 16 h/*** order to examine the“long term”photosynthetic characteristics,net photosynthetic rates of hydroponic lettuce leaves were continuously measured for 2 d(15^(th) and 16^(th) day after transplanting)before *** was no difference in leaf fresh weight(FW)between PPFD of 250μmol/m^(2)·s and 300μmol/m^(2)·s with photoperiod of 16 h/d,regardless of light quality,and same results showed in contents of nitrate,soluble sugar,and vitamin C,*** results of continuous measurements of net photosynthetic rate of lettuce leaves before harvest indicated that plants grown at PPFD of 250μmol/m^(2)·s had consistently higher compared to those grown at PPFD of 300μmol/m^(2)·*** the results from growth,photosynthesis,quality,and energy consumption,it can be concluded that PPFD at 250μmol/m^(2)·s with photoperiod of 16 h/d under LED with R:B ratio of 2.2 is a suitable light environment for maximum growth and high quality of commercial lettuce(***)production under indoor controlled environment.

关键词： plant factory daily light integral artificial light photosynthetic photon flux density net photosynthetic rate energy use efficiency

Comparative Evaluation of the Performance of SWAT, SWAT+, and APEX models in Simulating Edge of Field Hydrological Processes

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Open Journal of modelling and Simulation 2023年第2期11卷 37-49页

作者： Duncan Kikoyo Tobias Oker texas Water Resources Institute Texas A & M University College Station USA UC Cooperative extension University of California Bakersfield USA

Hydrologic and water quality models are often used in assessing the response of environmental processes to human activities and climatic change. However, these models differ in terms of their complexity, requirements, underlying equations, and assumptions, and as such their performance in simulating landscape processes varies. Consequently, a key question that has to be addressed is to select the most suitable model that gives results closest to reality for an intended purpose. In this study, the performance of the basin-wide older version of SWAT is compared with that of the small watershed model APEX to assess the performance of both models at a field scale level. The new restructured version of SWAT (SWAT+) is compared with the older version to determine whether the new changes incorporated in SWAT+ have improved model performance, particularly for small watersheds. The three models were used to simulate the edge of field processes for a 6.6 ha plot located at the USDA-Agricultural research Station near Riesel, texas, and to predict water yield, soil, and mineral phosphorous loss from the micro watershed. Results showed that all the uncalibrated models over-predict soil and phosphorous loss in a micro watershed. Uncalibrated SWAT and SWAT+ models simulated water yield satisfactory albeit with low-performance metrics. The calibrated versions simulated water yield with indices close to optimal values. PBIAS as a performance assessment metric was determined to be overly sensitive and prone to numerical errors. SWAT+ will be helpful in the understanding of hydrological and water quality processes at micro watersheds considering that it addresses structural flaws associated with the older version, and the manually calibrated version matches the performance of both APEX and SWAT, despite the latter two undergoing rigorous automatic calibration.

关键词： Erosion modelling Phosphorous Loss Riesel Water Yield

Comparative Assessment of Growth and Gene Regulation between 4 Serotypes of <i>Streptococcus pneumoniae</i>in Broth and Cell Culture

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Advances in microbiology 2018年第10期8卷 763-777页

作者： Ben Seabolt Jeff Brady Janice Speshock Department of Biological Sciences Tarleton State University Stephenville TX USA texas A&m agrilife research and extension center Stephenville TX USA

Streptococcus pneumoniae is a medically important pathogen capable of causing human infections of pneumonia, bacteremia, otitis media, and meningitis. Although there are vaccinations available, infections with S. pneumoniae still remains a global problem. S. pneumoniae is a highly adaptable bacterial species with numerous serotypes based on capsular polysaccharides. The different serotypes vary in their ability to colonize and causing pathology. Here we compared the regulation of five different virulence factors from four common serotypes of S. pneumoniae that vary in their carriage, morbidity, and mortality rates in the human population using two different in vitro methods, broth and cell culture. We determine that there is variation of virulence factor gene regulation within a serotype using two different culture methods, and variation between the serotypes in the same culture condition. The regulation of genes appeared to have a correlation with the ability of the various serotypes to grow in broth culture, adhere to cultured lung cells, and invade the cultured lung cells, as serotypes that shared similar regulation of virulence factors tended to behave similarly in culture. many studies with S. pneumoniae rely on the use of one selected serotype, but since there is a wide variation in the growth and regulatory mechanisms of these bacteria. As demonstrated here, future studies should utilize more strains in models before concluding mechanisms of pathobiology.

关键词： Pneumococcus Serotypes Gene Expression Regulation

Topographic differentiations of biological soil crusts and hydraulic properties in fixed sand dunes, Tengger Desert

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Journal of Arid Land 2015年第2期7卷 205-215页

作者： Zhi Shan ZHANG Yong Le CHEN Bin Xing XU Lei HUANG Hui Juan TAN Xue Jun DONG Shapotou Desert research and Experiment Station Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions of Gansu Province texas A&m Agri Life research and extension center at Uvalde

Biological soil crusts （BSCs） play an important role in surface soil hydrology. Soils dominated with moss BSCs may have higher infiltration rates than those dominated with cyanobacteria or algal BSCs. However, it is unnown whether improved infiltration in moss BSCs is accompanied by an increase in soil hydraulic conductivity or water retention capacity. We investigated this question in the Tengger Desert, where a 43-year-old revegetation program has promoted the formation of two distinct types of BSCs along topographic positions, i.e. the moss-dominated BSCs on the interdune land and windward slopes of the fixed sand dunes, and the al- gal-dominated BSCs on the crest and leeward slopes. Soil water retention capacity and hydraulic conductivity were measured using an indoor evaporation method and a field infiltration method. And the results were fitted to the van Genuchten-mualem model. Unsaturated hydraulic conductivities under greater water pressure （〈-0.01 mPa） and water retention capacities in the entire pressure head range were higher for both crust types than for bare sand. However, saturated and unsaturated hydraulic conductivities in the near-saturation range （〉-0.01 mPa） showed decreasing trends from bare sand to moss crusts and to algal crusts. Our data suggested that topographic differentiation of BSCs significantly affected not only soil water retention and hydraulic conductivities, but also the overall hydrology of the fixed sand dunes at a landscape scale, as seen in the reduction and spatial variability in deep soil water storage.

关键词： algal crusts hydraulic conductivity moss crusts soil water retention curve Tengger Desert

Fracture behavior of hybrid epoxy nanocomposites based on multi-walled carbon nanotube and core-shell rubber

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Nano materials Science 2022年第3期4卷 251-258页

作者： Zewen Zhu Hengxi Chen Qihui Chen Cong Liu Kwanghae Noh Haiqing Yao masaya Kotaki Hung-Jue Sue Department of materials Science and Engineering Texas A&M UniversityCollege StationTX77843-3003USA School of materials Science and Engineering North University of ChinaTaiyuan030051PR China Kaneka US materials research center FremontCA94555USA

The dispersion of nanoparticles plays a key role in enhancing the mechanical performance of polymer *** this work,one hybrid epoxy nanocomposite reinforced by a well dispersed,zinc oxide functionalized,multi-wall carbon nanotube (Zn O-mWCNT) and core-shell rubber (CSR) was prepared,which possesses both high modulus and fracture toughness while maintaining relatively high glass transition temperature (Tg).The improved fracture toughness from 0.82 mPa mfor neat epoxy to 1.46 mPa mfor the ternary epoxy nanocomposites is resulted from a series of synergistic toughening mechanisms,including cavitation of CSR-induced matrix shear banding,along with the fracture of mWCNTs and crack *** implication of the present study for the preparation of high-performance polymer nanocomposites is discussed.

关键词： Carbon nanotube Core-shell rubber Epoxy nanocomposites Fracture toughness Synergistic toughening effect

Non-invasive sensing techniques to phenotype multiple apple tree architectures

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Information Processing in Agriculture 2023年第1期10卷 136-147页

作者： Chongyuan Zhang Sara Serra Juan Quiro´s-Vargas Worasit Sangjan Stefano musacchi Sindhuja Sankaran Department of Biological Systems Engineering Washington State UniversityPullmanWA 99164USA Tree Fruit research&extension center Washington State UniversityWenatcheeWA 98801USA Department of Horticulture Washington State UniversityPullmanWA 99164USA

Tree fruit architecture results from combination of the training system and pruning and thinning processes across multiple growth and development ***,the tree fruit architecture contributes to the light interception and improves tree growth,fruit quality,and fruit yield,in addition to easing the process of orchard management and *** tree architectural traits are measured manually by researchers or growers,which is labor-intensive and *** this study,the remote sensing techniques were evaluated to phenotype critical architectural traits with the final goal to assist tree fruit breeders,physiologists and growers in collecting architectural traits efficiently and in a standardized *** this,a consumer-grade red–green–blue(RGB)camera was used to collect apple tree side-images,while an unmanned aerial vehicle(UAV)integrated RGB camera was programmed to image tree canopy at 15 m above ground level to evaluate multiple tree fruit *** sensing data were compared to ground reference data associated with tree orchard blocks within three training systems(Spindle,V-trellis,Biaxis),two rootstocks(‘WA 38 trees grafted on G41 and m9-Nic29)and two pruning methods(referred as bending and click pruning).The data were processed to extract architectural features from ground-based 2D images and UAV-based 3D digital surface *** traits extracted from sensing data included box-counting fractal dimension(DBs),middle branch angle,number of branches,trunk basal diameter,and tree row volume(TRV).The results from ground-based sensing data indicated that there was a significant(Pms,and correlations between DBs with tree height(r=0.79)and total fruit yield per unit area(r=0.74)were significant(Pmoreover,correlations between average or total TRV and ground reference data,such as tree height and total fruit yield per unit area,were significant(P<0.05).With the r

关键词： Tree training systems Tree row volume Unmanned aerial vehicle Image analysis

The off-site implications of deforestation on sedimentation rates and pollution in Abkenar open water (Anzali Lagoon, Caspian Sea) using radionuclide techniques and sediment quality indices

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International Journal of Sediment research 2022年第3期37卷 370-382页

作者： mohammadreza Gharibreza mohammad Zaman mahmood Arabkhedri Shahriar Sobh-Zahedi Soil Conservation and Watershed management research Institute Agricultural Research Education and Extension Organization (AREEO) Soil and Water management & Crop Nutrition Section Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture International Atomic Energy AgencyVienna International Centre Guilan Agricultural and Natural Resources research and Education center AREEO

Abkenar open water(AOW) has a 35 km~2 distribution and is the largest part of the Anzali Lagoon in the southern coastal zone of the Caspian Sea. The effects of deforestation in the upstream basin of the AOW were assessed by measuring the rate of sedimentation, sediment contamination, and ecological risk for aquatic life and end-users using radioisotopes Cesium-137 and Lead-210. The chronology of the AOW sediment column was studied using the Constant Rate of Supply model. Correlations between environmental changes and the sedimentary regime of the study area highlight the contribution of the AOW authorized international and local wood harvesting companies pre-and-post 1950 in the catchment in terms of the rate of sediment supply and the influx of toxic metals. Historical evidence shows that two specific layers formed during World Wars I and II with the mean rates of 0.185 ± 0.04(±STD) and 0.32 ± 0.02 kg/(m·y), respectively. The highest influx of alkali elements and toxic metals(nickel, cadmium, lead, zinc, and copper) into the basin occurred in 1945. Two layers of gray mud(16-50 cm) and organic-rich dark loss mud(0-16 cm) correlated well with the programmed wood harvesting *** layers accumulated from 1953 to 2000 with a mean rate of 0.6 ± 0.2 and 2 ± 0.7 kg/(m~2·y). Thus,aquatic life and end-users have been exposed to moderate to extremely high levels of toxic metals and a moderate level of contamination since the 1950 s.

关键词： Abkenar open water Accumulation rate Anzali Lagoon Sediment contamination CRS model Radioisotopes