10,098 research outputs found
Evaluation of Drifting Snow Susceptibility Based on GIS and GA-BP Algorithms
No full textDrifting snow, the flow of dispersed snow particles near ground level under the action of wind, is a major form of snow damage. When drifting snow occurs on railways, highways, and other transportation lines, it seriously affects their operational safety and results in drifting snow disasters. Drifting snow disasters frequently occur in the high latitudes of northwest China. At present, most scholars are committed to studying the prevention and control measures of drifting snow, but the prerequisite for prevention is to effectively evaluate the susceptibility of drifting snow along railways and highways to identify areas with a high risk of occurrence. Taking the Xinjiang Afukuzhun Railway as an example, this study uses a geographic information system (GIS) combined with on-site monitoring and surveys to establish a drifting snow susceptibility evaluation index system. The drifting snow susceptibility index (DSSI) is calculated through the weight of an evidence (WOE) model, and a genetic algorithm backpropagation (GA-BP) algorithm is used to obtain optimised evaluation index weights to improve the accuracy of model evaluation. The results show that the accuracies of the WOE model, WOE backpropagation (WOE-BP) model, and weight of evidence genetic algorithm backpropagation (WOE-GA-BP) model are 0.747, 0.748, and 0.785, respectively, indicating that the method can be effectively applied to evaluate drifting snow susceptibility
The UV to IR transmittance of Antarctic snow
No full textWe report the transmittance of Antarctic snow as a function of the thickness of snow layers, in the range between 350 and 900 nm. Samples were studied near Scott Base, Ross Island, and data are presented for measurements made in early December 1996. The transmittance followed the two flux theoretical expressions well, and scattering and absorption parameters were obtained by curve fitting. Scattering dominated the transmittance at shorter wavelengths. The absorption at shorter wavelengths varied from one site to another, being lowest for snow samples measured furthest away from Ross Island, suggesting the effects of blown volcanic dust. The snow albedo derived from the transmittance parameters is compared with those of other workers.PT: J; CR: BOHREN CF, 1974, J GEOPHYS RES, V79, P4527 DAVIS A, 1990, J GEOPHYS RES-ATMOS, V95, P11729 GRENFELL TC, 1977, J GLACIOL, V18, P445 GRENFELL TC, 1984, J GEOPHYS RES-OCEANS, V89, P3573 GRENFELL TC, 1994, J GEOPHYS RES-ATMOS, V99, P18669 ISHIMARU A, 1978, WAVE PROPAGATION SCA, V1, CH10 KORTUM G, 1969, REFLECTANCE SPECTROS, CH4 PEROVICH DK, 1991, GEOPHYS RES LETT, V18, P1233 WARREN SG, 1984, APPL OPTICS, V23, P1206 WEILER CS, 1994, ANTARCT RES SER, V62 WISCOMBE WJ, 1980, J ATMOS SCI, V37, P2712; NR: 11; TC: 11; J9: J GEOPHYS RES-ATMOS; PG: 9; GA: ZK155Source type: Electronic(1
Snow, Lenny
No full text"Quarterback Kim King (18) and Tailback Lenny Snow (41) of Georgia Tech are rated by many as the most explosive one-two punch in college football in 1966. King's home is Atlanta, Ga. And Snow is from Daytona Beach, Florida.
GA-Fuzzy PID control simulation waveform diagram.
No full textAs is well known, the metal annealing process has the characteristics of heat concentration and rapid heating. Traditional vacuum annealing furnaces use PID control method, which has problems such as high temperature fluctuation, large overshoot, and long response time during the heating and heating process. Based on this situation, some domestic scholars have adopted fuzzy PID control algorithm in the temperature control of vacuum annealing furnaces. Due to the fact that fuzzy rules are formulated through a large amount of on-site temperature data and experience summary, there is a certain degree of subjectivity, which cannot ensure that each rule is optimal. In response to this drawback, the author combined the technical parameters of vacuum annealing furnace equipment, The fuzzy PID temperature control of the vacuum annealing furnace is optimized using genetic algorithm. Through simulation and comparative analysis, it is concluded that the design of the fuzzy PID vacuum annealing furnace temperature control system based on GA optimization is superior to fuzzy PID and traditional PID control in terms of temperature accuracy, rise time, and overshoot control. Finally, it was verified through offline experiments that the fuzzy PID temperature control system based on GA optimization meets the annealing temperature requirements of metal workpieces and can be applied to the temperature control system of vacuum annealing furnaces.</div
Kanamycin resistance during in vitro development of pollen from transgenic tomato plants
No full textEffects of kanamycin on pollen germination and tube growth of pollen from non-transformed plants and from transgenic tomato plants containing a chimaeric kanamycin resistance gene were determined. Germination of pollen was not affected by the addition of kanamycin to the medium in both genotypes. Kanamycin, however, severely affected tube growth of pollen from non-transformed plants, while pollen from plants containing the chimaeric gene were less sensitive and produced significantly longer tubes at kanamycin concentrations between 200-400 mg l-1. Apparently, this resistance for kanamycin correlates with the expression of the chimaeric gene during male gametophytic development.
Holographic mensuration of suspended particles in aquatic systems
No full textThe distribution and dynamics of aggregates in the aquatic environment play an important role in the modelling of biogeochemical processes. Previous work on aggregates in the ocean (e.g. sedimentary 'marine snow' particles), which vary in size from tens of microns to several millimetres, has used electronic counting or conventional photography coupled with image analysis. Here we describe a non-destructive in situ approach by use of holographic mensuration, hologrammetry, that affords greater scope and higher accuracy for the enumeration, sizing, and spatial distribution determination of aggregate particles. By means of two complimentary techniques, in-line and offaxis transmission holography, we present the initial experiments conducted in our laboratory and discuss the preliminaiy results from real image analysis
The co-distribution of Plasmodium falciparum and hookworm among African schoolchildren.
No full textBACKGROUND: Surprisingly little is known about the geographical overlap between malaria and other tropical diseases, including helminth infections. This is despite the potential public health importance of co-infection and synergistic opportunities for control. METHODS: Statistical models are presented that predict the large-scale distribution of hookworm in sub-Saharan Africa (SSA), based on the relationship between prevalence of infection among schoolchildren and remotely sensed environmental variables. Using a climate-based spatial model of the transmission potential for Plasmodium falciparum malaria, adjusted for urbanization, the spatial congruence of populations at coincident risk of infection is determined. RESULTS: The model of hookworm indicates that the infection is widespread throughout Africa and that, of the 179.3 million school-aged children who live on the continent, 50.0 (95% CI: 48.9-51.1) million (27.9% of total population) are infected with hookworm and 45.1 (95% CI: 43.9-46) million are estimated to be at risk of coincident infection. CONCLUSION: Malaria and hookworm infection are widespread throughout SSA and over a quarter of school-aged children in sub-Saharan Africa appear to be at risk of coincident infection and thus at enhanced risk of clinical disease. The results suggest that the control of parasitic helminths and of malaria in school children could be viewed as essential co-contributors to promoting the health of schoolchildren
Increasing science, technology, engineering, and mathematics skills using Project Lead the Way
No full textIncludes bibliographical references
Retrieval of Dry Snow Parameters from Radiometric Data Using a Dense Medium Model and Genetic Algorithms
No full textIn this paper, GA-based techniques are used to invert the equations of an electromagnetic model based on Dense Medium Radiative Transfer Theory (DMRT) under the Quasi Crystalline Approximation with Coherent Potential to retrieve snow depth, mean grain size and fractional volume from microwave brightness temperatures. The technique is initially tested on both noisy and not-noisy simulated data. During this phase, different configurations of genetic algorithm parameters are considered to quantify how their change can affect the algorithm performance. A configuration of GA parameters is then selected and the algorithm is applied to experimental data acquired during the NASA Cold Land Process Experiment. Snow parameters retrieved with the GA-DMRT technique are then compared with snow parameters measured on field
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