Academic literature on the topic 'Pollen surface samples'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Pollen surface samples.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Pollen surface samples"
1
Paudayal, Khum N., and Ishan Gautam. "Scanning Electron Microscopic Studies on Surface Pattern of the Pollen Loads from Apis cerana in Jajarkot District." Nepal Journal of Science and Technology 12 (July 23, 2012): 340–49. http://dx.doi.org/10.3126/njst.v12i0.6522.
Full textAbstract:
Over nineteen species of pollen flora belonging to thirteen families were recovered from four pollen load samples from honey bee Apis cerana collected in Jajarkot district, mid-western region, Nepal. The pollen morphology was investigated using light microscopy along with scanning electron microscopy for correct identification of pollen to its lower taxonomic level and to contribute to melissopalynological studies originating from the native apiflora. The palynological assemblage identified to the generic and some up to species level belong to Alnus sp., Artemisia sp., Brassica sp., Cornus sp., Diploknema sp., Fraxinus sp., Ilex sp., Jasminum sp., Justicia sp., Ligustrum sp., Myrica esculenta, Salix sp., Strobilanthes sp., and Urtica sp. Some of the pollen grains identified to only family level, belong to, Acanthanceae, Compositae, Lamiaceae and Rosaceae. The identified pollens clearly reflect the botanical and geographical origins of the pollen load samples. Palynomorphological investigation included the description of pollen symmetry, polarity, ornamentation, aperture, shape and size. The results for the pollen assemblages and nectariferous plant sources of Jajarkot district are discussed.DOI: http://dx.doi.org/10.3126/njst.v12i0.6522 Nepal Journal of Science and Technology 12 (2011) 340-349
2
Dzyuba, O. F. "Pollen from surface samples as an environmental indicator." Paleontological Journal 40, S5 (October 2006): S584—S589. http://dx.doi.org/10.1134/s0031030106110050.
Full text
3
Quamar, Md Firoze, Biswajeet Thakur, Veeru Kant Singh, and Santosh Kumar Pandey. "Pollen heteromorphism in Schleichera Lour. (Sapindaceae), observed in surface soil samples from central India." Acta Palaeobotanica 61, no. 1 (June 2021): 32–41. http://dx.doi.org/10.35535/acpa-2021-0003.
Full textAbstract:
Angiosperms display striking variation of pollen morphological features within and between populations of the same species, as well as within individual plants. We describe and illustrate variation of pollen aperture number, which is called pollen heteromorphism, in Schleichera Lour. (Sapindaceae) from surface soil samples collected from central India, based on combined observations from light microscopy (LM) and confocal laser scanning microscopy (CLSM). Tri-zono-parasyncolporoidate pollen grains are, in general, known to occur in Schleichera Lour., but occasional tetra-zono-parasyncolporoidate pollen is also recorded, for the first time, from Chhattisgarh State, central India. Changes in ploidy level (diploidy/polyploidy), chromosome number, the C-value of DNA, completion of meiosis, as well as environmental factors and/or pollination ecology could be driving the occurrence of pollen heteromorphism. The present study could provide insights into the phylogeny and systematics, and has implications for pollen preservation as well.
4
Balakauskas, Lauras, Justina Gaižutytė, Vaidotas Valskys, and Giedrė Vaikutienė. "Analysis of pollen across the surface sediments of Lake Imbradas, Lithuania." Quaternary Research 106 (September 30, 2021): 113–28. http://dx.doi.org/10.1017/qua.2021.51.
Full textAbstract:
AbstractIn conventional pollen analysis, usually one sediment core per basin is analyzed to reconstruct past environmental conditions. This approach does not consider spatial heterogeneity of pollen assemblages, and assumes that one analyzed location is representative of the whole basin. To improve the spatial resolution of fossil pollen studies, further knowledge of the factors influencing variations in pollen assemblages throughout a basin is needed. We examined the spatial heterogeneity of pollen assemblages from 45 lacustrine surface samples from a lake with relatively simple hydrology and compared this dense network of surface pollen samples with the Lithuanian State Forest Service arboreal vegetation database. Calculations of pollen productivity at different locations across the lake revealed variations in the behavior of a pollen-vegetation relationship model in different parts of the basin. Our findings suggest that the model underestimated pollen contributions from the lakeshore vegetation. We demonstrate that detailed investigations of surface pollen as a step prior to fossil pollen investigations can provide useful insights, including understanding the influence of sedimentation rate on modelling results and spatial variations in pollen composition, thus providing guidance for site selection for fossil pollen studies.
5
Pellatt, Marlow G., Rolf W. Mathewes, and Ian R. Walker. "Pollen analysis and ordination of lake sediment-surface samples from coastal British Columbia, Canada." Canadian Journal of Botany 75, no. 5 (May 1, 1997): 799–814. http://dx.doi.org/10.1139/b97-090.
Full textAbstract:
Surficial sediment samples from 42 lakes, distributed from sea level to alpine elevations of coastal British Columbia and northwest Washington, were analyzed for pollen and spores. Pollen analysis revealed characteristic differences among the assemblages of the Coastal Western Hemlock, Mountain Hemlock, and Engelmann Spruce – Subalpine Fir biogeoclimatic zones (the Alpine zone is less clearly identifiable). Cluster analysis and detrended correspondence analysis (DCA) correctly group the sites according to their biogeoclimatic zones and also by geographic origin. DCA indicates a high correlation between the biogeoclimatic zones of the sample sites and annual precipitation (−0.89), January temperature (−0.77), annual temperature (−0.64), and growing-season precipitation (−0.68). Further analysis of the samples and eight environmental gradients using canonical correspondence analysis groups the pollen assemblages from the study sites into biogeoclimatic zones in relation to annual precipitation, growing-season precipitation, annual snowfall, annual temperature, and growing degree-days. These data are useful for testing whether or not postglacial pollen assemblages have modern analogues. Key words: modern pollen analysis, vegetation, ordination, multivariate statistical analysis, biogeoclimatic zones, British Columbia.
6
King, George A. "Vegetation and pollen relationships in eastern Canada." Canadian Journal of Botany 71, no. 2 (February 1, 1993): 193–210. http://dx.doi.org/10.1139/b93-022.
Full textAbstract:
The relationship between the vegetation and modern pollen assemblages in eastern Canada is summarized and analyzed using isopoll maps, ordination, and cluster analysis. The major vegetation zones are shrub tundra, forest tundra (divided into shrub and forest subzones), lichen woodland, closed black spruce forest, mixed boreal forest, and coastal barrens. The pollen assemblages of these zones are distinguished by differences in the relative abundance of a few important pollen types rather than by floristic differences. Northern zones have relatively high Cyperaceae and low Picea pollen percentages, and southern zones have high Picea and Abies pollen percentages. Surface samples from each vegetation zone generally form distinctive groups in the ordination analysis. However, samples from the shrub subzone of the forest tundra cluster with shrub tundra samples, and lichen woodland samples cluster with samples from the closed black spruce forest and the forest subzone of the forest tundra. Cluster analysis separates the samples into geographically distinct groups. However, these groups generally contain samples from several vegetation zones. The surface sample data set analyzed here will prove useful in reconstructing the vegetation history of the region. Key words: pollen surface samples, modern vegetation, eastern Canada.
7
Bunting, M. Jane, Barry G. Warner, and Clayton R. Morgan. "Interpreting pollen diagrams from wetlands: pollen representation in surface samples from Oil Well Bog, southern Ontario." Canadian Journal of Botany 76, no. 10 (October 1, 1998): 1780–97. http://dx.doi.org/10.1139/b98-158.
Full textAbstract:
Pollen and spore analysis of surface sediment samples from 45 points within Oil Well Bog, a coniferous swamp near Cambridge, Ontario, was used to determine the possibility of identifying different wetland vegetation communities from their palynological record, and to assess the effects of variable wetland vegetation on the pollen representation of surrounding upland communities. The data obtained were mapped for individual taxa to allow direct comparison of the spatial patterns of vegetation abundance and the associated palynological assemblages, and cluster analysis was used to identify palynologically similar assemblages. Some wetland communities, such as swamp dominated by black spruce, do have distinctive pollen signatures, but not all the vegetational diversity observed is reflected in the palynological data, with similar pollen assemblages deriving from some communities which are vegetationally very different (e.g., shrub swamps dominated by Chamaedaphne calyculata and Ilex verticillata). The wetland pollen assemblages do reflect much of the floristic diversity of the surrounding uplands, although the different communities receive varying proportions of their pollen influx from upland sources (varying from less than 5% to over 90%), and wide variations in the percentage of a given upland pollen morphotype can be found within quite a short distance, depending on the nature of local wetland communities.Key words: palynology, swamp, surface samples, wetland.
8
Bunting, M. Jane, Barry G. Warner, and Clayton R. Morgan. "Interpreting pollen diagrams from wetlands: pollen representation in surface samples from Oil Well Bog, southern Ontario." Canadian Journal of Botany 76, no. 10 (1998): 1780–97. http://dx.doi.org/10.1139/cjb-76-10-1780.
Full text
9
Isik, Ayla, Murat Ozdemir, and Ibrahim Doymaz. "Infrared drying of bee pollen: effects and impacts on food components." Czech Journal of Food Sciences 37, No. 1 (March 6, 2019): 69–74. http://dx.doi.org/10.17221/410/2017-cjfs.
Full textAbstract:
Infrared radiation drying being one of the innovative drying methods was chosen to perform comparative study at different infrared power levels at 50, 62, 74 and 88 W. Quality attributes such as protein, fat, ash, carbohydrate, vitamin C content, solubility index and colour of infrared dried bee pollen samples were evaluated. The infrared power has a significant effect on the drying and quality characteristics especially colour. Drying time was reduced from 170 to 50 min when the infrared power level increased from 50 W to 88 W. Morphological changes on the surface of bee pollen grains increased with increasing the infrared power. The bee pollen infrared dried at 50 W retained its quality characteristics better than the bee pollens infrared dried at other power levels.
10
Clayden, S. L., L. C. Cwynar, and G. M. MacDonald. "Stomate and pollen content of lake surface sediments from across the tree line on the Taimyr Peninsula, Siberia." Canadian Journal of Botany 74, no. 7 (July 1, 1996): 1009–15. http://dx.doi.org/10.1139/b96-125.
Full textAbstract:
Surface-sediment samples from 23 lakes on the Taimyr Peninsula were collected along a transect from tundra to forest and analyzed for their pollen and coniferous stomate content. Larix sibirica, the dominant tree in forest–tundra and forest vegetation zones, is poorly represented in the pollen spectra, never exceeding 8%. To examine the correspondence between the modern pollen rain and the vegetation zones of tundra, forest–tundra, and forest, a principal components analysis was applied to the pollen percentages. Betula and Alnus account for the greatest variance in the data set, and the set of tundra sites farthest north is distinct from the forest sites farthest south. Stomates of L. sibirica are present in all samples from sites where Larix trees are present, and some samples contained higher concentrations of stomates than pollen of Larix. Picea obovata stomates are found less consistently and less abundantly than Larix stomates.
Dissertations / Theses on the topic "Pollen surface samples"
1
Matthias, Isabelle. "Comparisons of modern pollen deposition with vegetation abundance and landscape pattern in NE-Germany." Thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-6027-B.
Full textAbstract:
Seit der Einführung der Pollenanalyse für Rekonstruktionen vergangener Vegetationsbedeckung befassen sich Wissenschaftler mit dem Einfluss von unterschiedlichen Pollenproduktionen der verschiedenen Arten sowie der Fragestellung, wie welches Gebiet in den Pollendaten widergespiegelt und interpretiert werden kann. Ziel dieser Arbeit war es den Zusammenhang zwischen Pollen und Vegetation weiter zu untersuchen. Dazu wurden Pollendaten von Oberflächenproben aus Brandenburger Seesedimenten sowie Pollenakkumulationsraten (PAR) von bleidatierten Sedimentkurzkernen mit Vegetationsdaten aus Waldinventurdaten und Biotopkartierungen verglichen.
Zu den wichtigen Ergebnissen der vorliegenden Arbeit gehören die Berechnungen von relativen und absoluten Pollenproduktionsraten (PPE und aPPE). Während die PPEs die verhältnismäßige Pollenproduktion der Arten zu einem Referenztaxon beschreiben, ist unter den aPPEs die Pollenproduktion pro Vegetationseinheit, in diesem Fall pro m³ (Biomasse), zu verstehen. Die Ergebnisse zeigen gleich hohe PPE-Werte für Fagus und Pinus und bestätigen im Allgemeinen die PPE-Werte aus Studien, die für andere Regionen Europas erhoben wurden. Die berechneten aPPE-Werte unterscheiden sich dagegen deutlich von den aPPE-Werten in Finnland, wo die aPPE für Pinus um ein zehnfaches geringer ist als in Brandenburg. Dieser Unterschied lässt sich möglicherweise mit einer höheren Nettoprimärproduktion der gleichen Biomasse in Zentraleuropa erklären. Darüber hinaus wurde der Einfluss von Blühalter und Waldstruktur auf PPE Berechnungen evaluiert. Die Ergebnisse zeigen, dass die Berücksichtigung beider Faktoren den größten Einfluss auf die Baumarten hat, die relativ spät den Kronenbereich bzw. ihr Blühalter erreichen, wie z.B. Fagus und Carpinus. Der geringste Einfluss dieser Faktoren zeigt sich für Arten, die bereits nach wenigen Jahren mit der Pollenproduktion beginnen, wie z.B. Betula und Alnus.
Für die Berechnung von PPEs und aPPEs muss ein Gebiet um den See (oder das Moor) ermittelt werden, in dem die Pollendaten mit der Vegetation verglichen werden können. Dieses Gebiet für die Berechnung von PPEs wird als „relevant source area of pollen“ (RSAP) bezeichnet. Die RSAP ist definiert als das Gebiet, in dem Pollenprozentdaten und Vegetationsprozentdaten den stärksten Zusammenhang zueinander aufweisen und es zu keiner besseren Korrelation der beiden Variablen in einer weiteren Distanz kommt. Die hier ermittelte RSAP für Brandenburg liegt bei sieben Kilometern und ist damit im Vergleich zu den meisten vorherigen Studien relativ groß. Diese relativ große RSAP lässt sich durch die Quartäre Landschaftsstruktur in Brandenburg erklären, welche durch großräumige Bestände einer Art oder Artenzusammensetzung charakterisiert ist. Des Weiteren zeigen die Ergebnisse dieser Arbeit erstmals, dass PAR für die einzelnen Hauptbaumarten in einem linearen Zusammenhang mit der seeumgebenen Biomasse stehen. Im Gegensatz zu der RSAP ist das Gebiet, welches am stärksten die Variationen der PAR erklärt, relativ klein und erstreckt sich von wenigen Metern bis maximal 2,5 Kilometer vom Seeufer. Die Größe dieses Gebiets variiert zwischen den Arten, was mit der Verbreitung des Pollens und der Abundanz der einzelnen Arten erklärt werden kann. Die Beobachtung, dass der Großteil des Pollens von der nahen Vegetation kommt, bestätigt den Einfluss einer „trunk space“-Komponente eines früheren konzeptuellen Pollenverbreitungsmodells. Die heute genutzten mathematischen Pollenverbreitungsmodelle berücksichtigen diese Komponente jedoch nicht. Nach den Erkenntnissen dieser Studie würde die Berücksichtigung dieser Komponente jedoch zu einer Verbesserung der angewandten Pollenverbreitungsmodelle führen.
Die oben genannten Datensätze wurden darüber hinaus für Vergleiche von verschiedenen Pollendiversitätsindexen mit Aspekten der Diversität der Landschaft genutzt. Die Ergebnisse zeigen, dass die Diversität der Pollen zu einem großen Teil mit der Diversität der Landschaft innerhalb eines Kilometers um den See herum erklärt werden kann. Während die nahe Vegetation hauptsächlich die Diversität erklärt, welche sich aus der Anzahl der Arten und deren Abundanz zusammensetzt, ist die „Palynological richness“ von einem größeren Gebiet beeinflusst (sieben Kilometer). Die Gleichverteilung von Pollenkörnen kann somit durch das Verhältnis zwischen der Diversität der Pollen und der „Palynological richness“ beschrieben werden, in dem ein größerer Wert eine größere Gleichverteilung der Arten beschreibt und umgekehrt.
Die Ergebnisse dieser Doktorarbeit zeigen, dass die Pollendaten in Abhängigkeit zur Fragestellung ein unterschiedlich großes Einzugsgebiet widerspiegeln. Ein größeres Einzugsgebiet der Pollen wird durch die Komposition der Pollenprozentdaten sowie der Anzahl der Pollentypen beschrieben. Die absolute Abundanz sowie die Diversität der ufernahen Vegetation kann dagegen durch PARs und die Diversität der Pollen interpretiert werden.
2
Shumilovskikh, Lyudmila. "Vegetation, climate and environmental dynamics of the Black Sea/Northern Anatolian region during the last 134 ka obtained from palynological analysis." Thesis, 2013. http://hdl.handle.net/11858/00-1735-0000-0001-BB0A-D.
Full textBooks on the topic "Pollen surface samples"
1
Palynological census data from surface samples in south Florida. Reston, VA: U.S. Geological Survey, 1997.
Find full text
2
M, Weimer Lisa, South Florida Water Management District (Fla.), and Geological Survey (U.S.), eds. Palynological census data from surface samples in south Florida. Reston, VA: U.S. Geological Survey, 1997.
Find full text
3
M, Weimer Lisa, Geological Survey (U.S.), and South Florida Water Management District (Fla.), eds. Palynological census data from surface samples in south Florida. Reston, VA: U.S. Geological Survey, 1997.
Find full text
4
Ellam, Rob. 8. Scratching the surface with cosmogenic isotopes. Oxford University Press, 2016. http://dx.doi.org/10.1093/actrade/9780198723622.003.0008.
Full textAbstract:
‘Scratching the surface with cosmogenic isotopes’ explains spallation—when a high energy cosmic ray particle removes several nucleons from an atom. Spallation produces 10Be from 16O in the atmosphere and rock surfaces, while spallation of silicon produces another cosmogenic isotope, 26Al. Cosmogenic isotope production is about four times greater at the poles than at the equator and is also greater at higher altitudes. To calculate a cosmogenic isotope exposure age, the latitude and altitude at which the sample was exposed needs to be known. Using ‘exposure’ and ‘burial’ methodologies, cosmogenic isotopes can be used to address various scientific problems such as recreating the seismic histories of tectonically active areas.
Book chapters on the topic "Pollen surface samples"
1
Hicks, S. "POLLEN METHODS AND STUDIES | Surface Samples and Trapping." In Encyclopedia of Quaternary Science, 2529–35. Elsevier, 2007. http://dx.doi.org/10.1016/b0-44-452747-8/00179-4.
Full text
2
Poska, A. "POLLEN METHODS AND STUDIES | Surface Samples and Trapping." In Encyclopedia of Quaternary Science, 839–45. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-444-53643-3.00179-5.
Full text
3
Bera, Samir. "Pollen-Spore Transport Into Antarctica and Possible Past Climatic Oscillations." In Geoscientific Investigations From the Indian Antarctic Program, 84–96. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-4078-0.ch004.
Full textAbstract:
During XIX-XX Indian Antarctic Expedition (IAE), two sediment cores were collected. The occurrence of the exotic pollen taxa like Larix, Ulmus, grasses, few herbs, local moss spores, and other cryptogams prove the activity of the palaeowind, which in turn caused transportation microbiota from a long distance. The study of pollen-spores accumulation in polar air (deduced from slide exposures from 40° S) to Antarctic mainland studied for two years (2000 and 2001) as well as surface deposits (45 moss tuft, 15 lichen samples, 10 frozen soils, 10 moraine matrix) is well corroborated with lake sediment study. Ten bulk ice samples from the Antarctic ice cap (5 litres of ice melt) from Schirmacher Oasis were studied to recover trapped palynodebris to understand the depositional pattern of various microbiota in the Antarctic ice sheet.
4
Deniz Karaoglan, Aslan, Deniz Perin, and Kemal Yilmaz. "Design Optimization of 18-Poled High-Speed Permanent Magnet Synchronous Generator." In Artificial Intelligence. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106987.
Full textAbstract:
The aim of this research is to optimize the design of an 18-poled 8000 rpm 7 kVA high-speed permanent magnet synchronous generator. The goal is to find the best factor levels for the design parameters, namely magnet thickness (MH), offset, and embrace (EMB) to optimize the responses namely efficiency (%), rated torque (N.m), air-gap flux density (Tesla), armature current density (A/mm2), armature thermal load (A2/mm3). The aim is to keep the air-gap flux density at 1 tesla while maximizing efficiency and minimizing the rest of the responses. Optimization was carried out with one sample algorithm selected from each of the commonly used optimization algorithm classifications. For this purpose, different class of well-known optimization techniques such as response surface methodology (gradient-based methods), genetic algorithm (evolutionary-based algorithms), particle swarm optimization algorithm (swarm-based optimization algorithms), and modified social group optimization algorithm (human-based optimization algorithms) are selected. In the Ansys Maxwell environment, numerical simulations are carried out. Mathematical modeling and optimizations are performed by using Minitab and Matlab, respectively. Confirmations are also performed. Results of the comparisons show that modified social group optimization and particle swarm optimization algorithms a bit outperform the response surface methodology and genetic algorithm, for this design problem.
Conference papers on the topic "Pollen surface samples"
1
Beb, Mayra Yucely, Sounkalo Dembélé, Akkiz Bekel, Isabelle Jouffroy-Bapicot, Sébastien Thibaud, Nadine Piat, Olivier Lehmann, et al. "Proposal for a complete 3D surface reconstruction using images from a scanning electron microscope (SEM)." In Frontiers in Optics. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/fio.2022.jw5a.69.
Full textAbstract:
A three-dimensional model enables the development of accurate solutions to have more information about the thickness, texture, and characteristics of small-size samples for education and metrology applications. This project proposes an idea to obtain a complete 3D surface reconstruction using the application of Pollen 3D for the scanning electron microscope (SEM) images with high magnification. The main objective is to have a set of images of the complete 360° rotation of the sample with a robot inside the chamber of the SEM. Simulation SEM images with Blender (open source application) are proposed for results validation.
2
Shefer, N. V., L. S. Shumilovskikh, and I. I. Gureyeva. "Sub-recent palynological spectra of landscapes of the Yamalo-Nenets Autonomous Area, Russia." In Problems of studying the vegetation cover of Siberia. TSU Press, 2020. http://dx.doi.org/10.17223/978-5-94621-927-3-2020-47.
Full textAbstract:
An analysis of the composition of surface spore-pollen spectra (SPS) was carried out within a gradient from forest-tundra to northern taiga. In total, 20 sub-recent moss-lichen surface samples were obtained on the territory of the Nadymsky and Purovsky districts of Yamalo-Nenets Autonomous Area. All studied spectra contain pollen of Larix sibirica Ledeb., Picea obovata Ledeb., Pinus sibirica Du Tour, P. sylvestris L., Betula pubescens Ehrh., B. nana L, as well as Ericaceae, Asteraceae and Cyperaceae. In the SPS of the studied communities, an increase in the participation of the pollen of Pinus species, a decrease in the content of Betula nana pollen, and an increase in the diversity of the taxonomic composition of herbs at the transition from the forest-tundra to the northern taiga are observed. The low content of Picea obovata pollen in the forest-tundra and northern taiga spectra reflects the low proportion of spruce in the studied communities. The low pollen proportion of Larix sibirica in the forest-tundra and northern taiga does not reflect the actual participation of L. sibirica in the vegetation cover, but is associated with rapid destruction of pollen and its low flight ability. The low content of Larix sibirica pollen in the forest-tundra and northern taiga does not reflect the actual participation of larch in the stand.
3
Zuegner, Mario Andre. "Ice moon research – A phenomenon called plume." In Symposium on Space Educational Activities (SSAE). Universitat Politècnica de Catalunya, 2022. http://dx.doi.org/10.5821/conference-9788419184405.102.
Full textAbstract:
Based on the observations of the Cassini-Huygens space exploration mission, Saturn's moon Enceladus was found to be a very promising subject in the solar system for further exploration and follow-up research, especially focusing on the potential of extraterrestrial life and its origin.
Near its South Pole, fountains, specified plumes, consisting mostly of water vapor and small salt-rich ice grains with intermittent activity were observed at the surface. With supersonic speed the water vapor is exiting the trenches known as Tiger Stripes. The driving force of these plumes are not completely understood yet. In current models, Enceladus is expected to consist of a rocky core, surrounded by an ocean of liquid water and covered by a layer of ice. The observed phenomenon is assumed to be caused by the tidal forces that act upon Enceladus. However, several models try to describe the underlying physical processes. Various investigations have recognized the astrobiological potential of Enceladus, even proposed a concept for a sample return for further research in relation to the subsurface ocean. Cassini ́s existing analysis already identified CH4, CO, CO2, simple and complex organics at an altitude of approximately 190 km which allow the assumption of supersonic speeds. That said, the goal of our experiment is to gain further indices/evidence to support the current models of the plumes. Our experiment takes place on a sounding rocket which gives access to a stable vacuum and microgravity in addition. The achieved altitude with its physical environment provides almost the conditions at Enceladus related to the gravitation. The rocket module contains a pressurized and heated water reservoir which is connected via an injection system with the evaporation chamber. On the top a convergent-divergent nozzle is welded. Furthermore a nozzle cover system and a locking mechanism are integrated. At apogee, the nozzle shall be opened and the fluid stream (assumingly made up of ice, water droplets and vapor) shall exit the module at about Mach 2. The necessary fluid-dynamic data is gathered by multiple temperature and pressure measurements at different points on the module. So, the vapor stream shall be compared to the expectations based on the models. Finally it is to mention that our project is still running and waiting for its launch. Caused through the Corona crisis and the Ukraine war the launch cycle was canceled two years in succession. With much luck the rocket will launch in March 2023.
4
Arndt, Mark W. "Recorded Responses of a Light Truck With Rapid Left Front Air-Out of Super Oversized Mud Tires." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-53225.
Full textAbstract:
A closed-loop test of a 1974 Ford F-150 4WD truck equipped with super oversized off-road mud tires was conducted to demonstrate that steering was possible after a left front rapid air-out event. A rim was built with six remotely deployable orifices that activated simultaneously and caused the air pressure to decrease below 2.5 psi in less than one second. The truck was configured in OEM condition except for the tires and rims. The tires were 42–14X16 mounted to 8X16 rims with zero offset. The tires that were originally sold with the vehicle were probably 8.75–16.5. Three tests at increasing speed of 35 mph, 45 mph, and 55 mph were conducted on a large, remote, and closed parking lot in a two-lane travel way marked with surface paint. The truck, while monitored with a standard suite of instruments and video, was brought to speed in a straight-line. At a predetermined point, and while maintaining a straight path, the throttle was dropped and the left front tire air-out was remotely triggered. The driver, aware of the test conditions and with the benefit of experience, was instructed to steer the truck to maintain its position within the simulated traffic lanes. The truck was equipped with a four-speed manual transmission which remained in fourth gear throughout the response phase of the test. The clutch was depressed and brakes applied only after steering control had corrected the vehicle’s leftward motion. The post air-out path of the truck evidenced by printing from the left front tire in each test was measured, photographed and plotted. The truck never left the simulated roadway travel lanes, which represented one direction of a typical four-lane California state highway. The test data was recorded at 200 samples per second and was post-processed with a 6 HZ, 12-pole, phaseless digital filter. Test results were plotted and presented. The test results are of interest because they are a demonstration of the concept that even under extreme conditions, if a test driver knows what is going to happen and knows what to do, a controlled vehicle motion is the likely outcome. In the tests, as the driver gained experience and the speed increased, lateral motion decreased. These findings are consistent with conclusions in a NHTSA tread separation study including, “when drivers had prior knowledge of the imminent tread separation, they were significantly less likely to sustain loss of vehicle control following the tread separation.” And, “findings from test track studies in which test drivers were aware of an imminent tread separation may underestimate the extent to which tread separation occurring in the real world leads to instability and loss of vehicle control.”
Reports on the topic "Pollen surface samples"
1
Hodul, M., H. P. White, and A. Knudby. A report on water quality monitoring in Quesnel Lake, British Columbia, subsequent to the Mount Polley tailings dam spill, using optical satellite imagery. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330556.
Full textAbstract:
In the early morning on the 4th of August 2014, a tailings dam near Quesnel, BC burst, spilling approximately 25 million m3 of runoff containing heavy metal elements into nearby Quesnel Lake (Byrne et al. 2018). The runoff slurry, which included lead, arsenic, selenium, and vanadium spilled through Hazeltine Creek, scouring its banks and picking up till and forest cover on the way, and ultimately ended up in Quesnel Lake, whose water level rose by 1.5 m as a result. While the introduction of heavy metals into Quesnel Lake was of environmental concern, the additional till and forest cover scoured from the banks of Hazeltine Creek added to the lake has also been of concern to salmon spawning grounds. Immediate repercussions of the spill involved the damage of sensitive environments along the banks and on the lake bed, the closing of the seasonal salmon fishery in the lake, and a change in the microbial composition of the lake bed (Hatam et al. 2019). In addition, there appears to be a seasonal resuspension of the tailings sediment due to thermal cycling of the water and surface winds (Hamilton et al. 2020). While the water quality of Quesnel Lake continues to be monitored for the tailings sediments, primarily by members at the Quesnel River Research Centre, the sample-and-test methods of water quality testing used, while highly accurate, are expensive to undertake, and not spatially exhaustive. The use of remote sensing techniques, though not as accurate as lab testing, allows for the relatively fast creation of expansive water quality maps using sensors mounted on boats, planes, and satellites (Ritchie et al. 2003). The most common method for the remote sensing of surface water quality is through the use of a physics-based semianalytical model which simulates light passing through a water column with a given set of Inherent Optical Properties (IOPs), developed by Lee et al. (1998) and commonly referred to as a Radiative Transfer Model (RTM). The RTM forward-models a wide range of water-leaving spectral signatures based on IOPs determined by a mix of water constituents, including natural materials and pollutants. Remote sensing imagery is then used to invert the model by finding the modelled water spectrum which most closely resembles that seen in the imagery (Brando et al 2009). This project set out to develop an RTM water quality model to monitor the water quality in Quesnel Lake, allowing for the entire surface of the lake to be mapped at once, in an effort to easily determine the timing and extent of resuspension events, as well as potentially investigate greening events reported by locals. The project intended to use a combination of multispectral imagery (Landsat-8 and Sentinel-2), as well as hyperspectral imagery (DESIS), combined with field calibration/validation of the resulting models. The project began in the Autumn before the COVID pandemic, with plans to undertake a comprehensive fieldwork campaign to gather model calibration data in the summer of 2020. Since a province-wide travel shutdown and social distancing procedures made it difficult to carry out water quality surveying in a small boat, an insufficient amount of fieldwork was conducted to suit the needs of the project. Thus, the project has been put on hold, and the primary researcher has moved to a different project. This document stands as a report on all of the work conducted up to April 2021, intended largely as an instructional document for researchers who may wish to continue the work once fieldwork may freely and safely resume. This research was undertaken at the University of Ottawa, with supporting funding provided by the Earth Observations for Cumulative Effects (EO4CE) Program Work Package 10b: Site Monitoring and Remediation, Canada Centre for Remote Sensing, through the Natural Resources Canada Research Affiliate Program (RAP).