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1
Leeson, A. A., A. Shepherd, S. Palmer, A. Sundal, and X. Fettweis. "Simulating the growth of supra-glacial lakes at the western margin of the Greenland ice sheet." Cryosphere Discussions 6, no. 2 (March 30, 2012): 1307–36. http://dx.doi.org/10.5194/tcd-6-1307-2012.
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Abstract. We present a method of modelling the growth of supra-glacial lakes at the western margin of the Greenland ice sheet, based on routeing runoff estimated by a Regional Climate Model (RCM) across a digital elevation model (DEM) of the ice sheet surface. Using data acquired during the 2003 melt season, we demonstrate that the model is 18 times more likely to correctly predict the presence or absence of lakes identified in MODIS satellite imagery within an elevation range of 1000 to 1600 metres above sea level (m.a.s.l.) than it is to make incorrect predictions. Our model does not, however, simulate processes leading to lake stagnation or decay, such as refreezing or drainage – a process which affects approximately 17% of lakes in our study area (Selmes et al., 2011). This likely explains much of why our model over-predicts cumulative area by 32% although other factors including uncertainty in the DEM and in the MODIS derived observations used for validation contribute to this error. Simulated lake filling tends to lead observations by approximately 5 days which could be related to a filling period required to saturate cracks, crevasses and other porous space within the ice. We find that the maximum modelled lake covered ice sheet area is 6% and suggest that this is a topographic limitation for this sector. We can take this as an upper bound; given the absence of drainage in the model. In 2003, the difference between RCM estimates of runoff and the maximum volume of water simulated to be stored in lakes was 12.49 km3. This can be taken as a measure of potential water available for lubrication and is calculated to be 1.86 m3 per square metre of ice. This study has proved a good first step towards capturing the variability of supra-glacial lake evolution with a numerical model; we are optimistic that the model will develop further into a useful tool for use in analysing the behaviour of supra-glacial lakes on the Greenland ice sheet in the present day and beyond.
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Huang, Y. S., and O. H. Yeoh. "Crack Initiation and Propagation in Model Cord-Rubber Composites." Rubber Chemistry and Technology 62, no. 4 (September 1, 1989): 709–31. http://dx.doi.org/10.5254/1.3536270.
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Abstract The present study suggests that the development of penny-shaped cracks at cord ends is the first stage of fatigue failure of cord-rubber composites. An approximate theory for calculating the strain-energy release rate (tearing energy) for the propagation of penny-shaped cracks and predicting the life of model composites has been outlined. The basic premise of this theory is that the rate of propagation of these penny-shaped cracks is governed by the usual crack-growth characteristics of rubber vulcanizates customarily determined using simple test pieces such as the pure-shear test piece. Fatigue studies on two model composites show experiment and theory to be in semiquantitative agreement. Breidenbach and Lake have already established the relationship between the crack-growth characteristics of the rubber material to interply crack propagation, a later stage in the fatigue failure of cord-rubber composites. Therefore, it is clear that the crack-growth characteristics are an important screening criterion for compound development aimed at improving the life of cord-rubber composites.
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Jitprasithsiri, Siriphan, Hosin Lee, Robert G. Sorcic, and Richard Johnston. "Development of Digital Image-Processing Algorithm to Compute Unified Crack Index for Salt Lake City." Transportation Research Record: Journal of the Transportation Research Board 1526, no. 1 (January 1996): 142–48. http://dx.doi.org/10.1177/0361198196152600118.
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This paper presents the recent efforts in developing an image processing algorithm for computing a unified pavement crack index for Salt Lake City. The pavement surface images were collected using a digital camera mounted on a van. Each image covers a pavement area of 2.13 m (7 ft) × 1.52 m (5 ft), taken at every 30-m (100-ft) station. The digital images were then transferred onto a 1-gigabyte hard disk from a set of memory cards each of which can store 21 digital images. Approximately 1,500 images are then transferred from the hard disk to a compact disc. The image-processing algorithm, based on a variable thresholding technique, was developed on a personal computer to automatically process pavement images. The image is divided into 140 smaller tiles, each tile consisting of 40 × 40 pixels. To measure the amount of cracking, a variable threshold value is computed based on the average gray value of each tile. The program then automatically counts the number of cracked tiles and computes a unified crack index for each pavement image. The crack indexes computed from the image-processing algorithms are compared against the manual rating procedure in this paper. The image-processing algorithms were applied to process more than 450 surveyed miles of Salt Lake City street network.
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Kavanaugh, Jeffrey, Ryan Schultz, Laurence D. Andriashek, Mirko van der Baan, Hadi Ghofrani, Gail Atkinson, and Daniel J. Utting. "A New Year’s Day icebreaker: icequakes on lakes in Alberta, Canada." Canadian Journal of Earth Sciences 56, no. 2 (February 2019): 183–200. http://dx.doi.org/10.1139/cjes-2018-0196.
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Any process that causes a sudden brittle failure of material has the potential to cause earthquake-like seismic events. Cryoseisms represent an underreported class of seismic event due to their (often) small magnitudes. In this paper, we document the phenomenon of some of the largest magnitude lake-associated icequakes (ML 2.0) yet reported. These events occurred nearly simultaneously (within ∼2 h) on geographically separate lakes in Alberta, Canada, starting 1 January 2018. We conjecture that these events were caused by the sudden brittle failure of lake ice due to thermal expansion; the effects of the thermal expansion were compounded by the lack of insulating snow cover, high lake water levels, and a rapid onset of atmospheric warming. These factors also contributed to ice-jacking — a repeating process in which thermal contraction produces tensile cracks (leads) in lake ice that are then filled with water that is frozen during the cooling cycle. Thus, any subsequent thermal expansion must be accommodated by new deformation or brittle failure. This ice-jacking process caused creeping ground deformation after the initial brittle failure and again two weeks later following a second warming period. In many cases, the resulting ground deformation was significant enough to cause property damage.
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Rong, Jigang, Jun Yang, Youjian Huang, Wenbo Luo, and Xiaoling Hu. "Characteristic Tearing Energy and Fatigue Crack Propagation of Filled Natural Rubber." Polymers 13, no. 22 (November 10, 2021): 3891. http://dx.doi.org/10.3390/polym13223891.
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Below the incipient characteristic tearing energy (T0), cracks will not grow in rubber under fatigue loading. Hence, determination of the characteristic tearing energy T0 is very important in the rubber industry. A rubber cutting experiment was conducted to determine the T0, using the cutting method proposed originally by Lake and Yeoh. Then, a fatigue crack propagation experiment on a edge-notched pure shear specimen under variable amplitude loading was studied. A method to obtain the crack propagation rate da/dN from the relationship of the crack propagation length (Δa) with the number of cycles (N) is proposed. Finally, the T0 obtained from the cutting method is compared with the value decided by the fatigue crack propagation experiment. The values of T0 obtained from the two different methods are a little different.
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Manasypov, R. M., S. N. Vorobyev, S. V. Loiko, I. V. Kritzkov, L. S. Shirokova, V. P. Shevchenko, S. N. Kirpotin, et al. "Seasonal dynamics of organic carbon and metals in thermokarst lakes from the discontinuous permafrost zone of western Siberia." Biogeosciences 12, no. 10 (May 21, 2015): 3009–28. http://dx.doi.org/10.5194/bg-12-3009-2015.
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Abstract. Despite relatively good knowledge of the biogeochemistry of Siberian thermokarst lakes during summer base flow, their seasonal dynamics remains almost unexplored. This work describes the chemical composition of ~130 thermokarst lakes ranging in size from a few m2 to several km2, located in the discontinuous permafrost zone. Lakes were sampled during spring flood, just after the ice break (early June), the end of summer (August), the beginning of ice formation (October) and during the full freezing season in winter (February). The lakes larger than 1000 m2 did not exhibit any statistically significant control of the lake size on dissolved organic carbon (DOC), the major and trace element concentrations over three major open water seasons. On the annual scale, the majority of dissolved elements including organic carbon increased their concentration from 30 to 500%, with a statistically significant (p < 0.05) trend from spring to winter. The concentrations of most trace elements (TEs) increased in the order spring > summer > autumn > winter. The ice formation in October included several stages: first, surface layer freezing followed by crack (fissure) formation with unfrozen water from the deeper layers spreading over the ice surface. This water was subsequently frozen and formed layered ice rich in organic matter. As a result, the DOC and metal (Mn, Fe, Ni, Cu, Zn, As, Ba and Pb) concentrations were highest near the surface of the ice column (0 to 20 cm) and decreased by a factor of 2 towards the bottom. The main implications of discovered freeze-driven solute concentrations in thermokarst lake waters are enhanced colloidal coagulation and removal of dissolved organic matter and associated insoluble metals from the water column to the sediments. The measured distribution coefficients of a TE between amorphous organo-ferric coagulates and lake water (<0.45 μm) were similar to those reported earlier for Fe-rich colloids and low molecular weight (<1 kDa, or <1–2 nm) fractions of thermokarst lake waters, suggesting massive co-precipitation of TE with amorphous Fe oxyhydroxide stabilized by organic matter. Although the concentration of most elements was lowest in spring, this period of maximal water coverage of land created a significant reservoir of DOC and soluble metals in the water column that can be easily mobilized to the hydrological network. The highest DOC concentration observed in the smallest (<100 m2) water bodies in spring suggests their strongly heterotrophic status and, therefore, a potentially elevated CO2 flux from the lake surface to the atmosphere.
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Mackay, J. Ross. "The first 7 years (1978–1985) of ice wedge growth, Illisarvik experimental drained lake site, western Arctic coast." Canadian Journal of Earth Sciences 23, no. 11 (November 1, 1986): 1782–95. http://dx.doi.org/10.1139/e86-164.
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A large lake, measuring 600 m × 300 m and with a depth of nearly 5 m, was artificially drained on 13 August 1978. Observations on the formation, width, and depth of thermal contraction cracks for the first 7 years show that the crack profiles and ice wedge growth rates differ markedly from those of old ice wedges reported in the literature. The first winter's cracks had box-like profiles, with surface widths to 10 cm and depths to 2.5 m. Some cracks continued to widen and deepen, once opened in early winter, and then narrowed or even closed completely in summer. Mean growth rates for the ice wedges for the first few years have been as much as 3.5 cm/year. Temperature gradients at the time of first cracking have been in the range of 10–15 °C/m. The growth rate of young ice wedges is site specific and temperature dependent, varying with factors such as the temperature gradient, vegetation, and snow cover, so an estimate of the age of an ice wedge from its width will usually be impossible. A study of crack widths indicates that the apparent coefficient of linear expansion of frozen ground may be several times that of ice. Upward cracking has been proven.
8
Mackay, J. Ross. "The sound and speed of ice-wedge cracking, Arctic Canada." Canadian Journal of Earth Sciences 30, no. 3 (March 1, 1993): 509–18. http://dx.doi.org/10.1139/e93-040.
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Rifle-like sounds produced by ice-wedge cracking, although seldom heard, have been reported in the permafrost literature for a century. The sounds, similar to those produced by the rapid cracking of lake ice, indicate a high speed of crack propagation. The speed of ice-wedge crack propagation has been measured at two field sites for the 1966-1989 period. No evidence of rapid crack propagation has been detected at these sites. The fracture patterns of ribs, as seen on vertical crack faces, and the numerous short interacting cracks, as seen in plan view, suggest slow rates of cracking. Enquiries made of many northern residents indicate that rifle-like sounds are uncommon along the mainland coast from the Alaska–Yukon boundary eastward to Coppermine, N.W.T. but are heard more frequently in the Arctic islands. High speeds of crack propagation appear associated with sharp drops in temperature, windblown sites, and long, straight ice wedges. As a preliminary estimate, crack propagation rates exceeding about 200 m/s are necessary to produce rifle-like sounds and accompanying ground tremors.
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Dupont, Todd K., and Richard B. Alley. "Conditions for the reversal of ice/air surface slope on ice streams and shelves: a model study." Annals of Glaciology 40 (2005): 139–44. http://dx.doi.org/10.3189/172756405781813780.
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AbstractReversals in the ice/air surface slope are important in geomorphic and glaciological contexts, thus motivating consideration of the conditions under which they form. Surface slope reversals are seen in numerous places, such as ice rumples on ice shelves, as surficial lakes, and at the down-glacier end of Vostok lake, Antarctica. Such slope reversals can reduce or reverse the subglacial hydrological gradient, thereby rerouting subglacial water transport and possibly leading to the creation of subglacial lakes. Supraglacial lakes produced by slope reversals in ablation zones may aid in driving water-filled cracks that allow surface water access to the bed. Surface slope reversals, in the absence of a concomitant reversal in ice flow, indicate a local violation of the so-called ‘shallow-ice’ approximation, and in this circumstance the longitudinal deviatoric stress becomes critical in the stress equilibrium. Using a simple numerical model, we have explored the conditions under which surface slope reversals form for certain simple scenarios. The results indicate that ice which initially possesses a normal slope will tend toward a reversed slope if the ice is thinned, the bed is strengthened or the downstream buttressing is increased.
10
Manasypov, R. M., S. N. Vorobyev, S. V. Loiko, I. V. Kritzkov, L. S. Shirokova, V. P. Shevchenko, S. N. Kirpotin, et al. "Seasonal dynamics of organic carbon and metals in thermokarst lakes from the discontinuous permafrost zone of western Siberia." Biogeosciences Discussions 12, no. 2 (January 30, 2015): 1975–2019. http://dx.doi.org/10.5194/bgd-12-1975-2015.
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Abstract. Western Siberia's thermokarst (thaw) lakes extend over a territory spanning over a million km2; they are highly dynamic hydrochemical systems that receive chemical elements from the atmosphere and surrounding peat soil and vegetation, and exchange greenhouse gases with the atmosphere, delivering dissolved carbon and metals to adjacent hydrological systems. This work describes the chemical composition of ~ 130 thermokarst lakes of the size range from a few m2 to several km2, located in the discontinuous permafrost zone. Lakes were sampled during spring floods, just after the ice break (early June), the end of summer (August), the beginning of ice formation (October) and during the full freezing season in winter (February). Dissolved organic carbon (DOC) and the major and trace elements do not appreciably change their concentration with the lake size increase above 1000 m2 during all seasons. On the annual scale, the majority of dissolved elements including organic carbon increase their concentration from 30 to 500%, with a statistically significant (p < 0.05) trend from spring to winter. The maximal increase in trace element (TE) concentration occurred between spring and summer and autumn and winter. The ice formation in October included several stages: first, surface layer freezing followed by crack (fissure) formation with unfrozen water from the deeper layers spreading over the ice surface. This water was subsequently frozen and formed layered ice rich in organic matter. As a result, the DOC and metal concentrations were the highest at the beginning of the ice column and decreased from the surface to the depth. A number of elements demonstrated the accumulation, by more than a factor of 2, in the surface (0–20 cm) of the ice column relative to the rest of the ice core: Mn, Fe, Ni, Cu, Zn, As, Ba and Pb. The main consequences of discovered freeze-driven solute concentrations in thermokarst lake waters are enhanced colloidal coagulation and the removal of dissolved organic matter and associated insoluble metals from the water column to the sediments. The measured distribution coefficient of TE between amorphous organo-ferric coagulates and lake water (< 0.45 μm) were similar to those reported earlier for Fe-rich colloids and low molecular weight (< 1 kDa) fractions of thermokarst lake waters, suggesting massive co-precipitation of TE with amorphous Fe oxy(hydr)oxide stabilized by organic matter. Although the concentration of most elements is lowest in spring, this period of maximal water coverage of land creates a significant reservoir of DOC and soluble metals in the water column that can be easily mobilized to the hydrological network. The highest DOC concentration observed in the smallest (< 100 m2) water bodies in spring suggests their strongly heterotrophic status and, therefore, elevated CO2 flux from the lake surface to the atmosphere.
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De Blasio, Fabio Vittorio. "The Large Dendritic Morphologies in the Antoniadi Crater (Mars) and Their Potential Astrobiological Significance." Geosciences 12, no. 2 (January 24, 2022): 53. http://dx.doi.org/10.3390/geosciences12020053.
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Mars has held large amounts of running and standing water throughout its history, as evidenced by numerous morphologies attributed to rivers, outflow channels, lakes, and possibly an ocean. This work examines the crater Antoniadi located in the Syrtis Major quadrangle. Some parts of the central area of the crater exhibit giant polygonal mud cracks, typical of endured lake bottom, on top of which a dark, tens of kilometers-long network of dendritic (i.e., arborescent) morphologies emerges, at first resembling the remnant of river networks. The network, which is composed of tabular sub-units, is in relief overlying hardened mud, a puzzling feature that, in principle, could be explained as landscape inversion resulting from stronger erosion of the lake bottom compared to the endured crust of the riverine sediments. However, the polygonal mud cracks have pristine boundaries, which indicate limited erosion. Furthermore, the orientation of part of the network is the opposite of what the flow of water would entail. Further analyses indicate the similarity of the dendrites with controlled diffusion processes rather than with the river network, and the presence of morphologies incompatible with river, alluvial, or underground sapping processes, such as overlapping of branches belonging to different dendrites or growth along fault lines. An alternative explanation worth exploring due to its potential astrobiological importance is that the network is the product of ancient reef-building microbialites on the shallow Antoniadi lake, which enjoyed the fortunate presence of a heat source supplied by the Syrtis Major volcano. The comparison with the terrestrial examples and the dating of the bottom of the crater (formed at 3.8 Ga and subjected to a resurfacing event at 3.6 Ga attributed to the lacustrine drape) contribute to reinforcing (but cannot definitely prove) the scenario of microbialitic origin for dendrites. Thus, the present analysis based on the images available from the orbiters cannot be considered proof of the presence of microbialites in ancient Mars. It is concluded that the Antoniadi crater could be an interesting target for the research of past Martian life in future landing missions.
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Wang, Jingfeng, Guang Liu, Zhaodong Ding, Hanbing Bian, and Huayan Yao. "Progresses on the intelligent construction and operation maintenance of urban under-lake tunnels." MATEC Web of Conferences 295 (2019): 01006. http://dx.doi.org/10.1051/matecconf/201929501006.
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China is currently at an important stage of urbanization. In recent years, the number and scale of under-lake tunnels in southern cities of China are growing consistently, which brings opportunities and challenges in intelligent construction and operation maintenance. Due to the long length of the under-lake tunnel, the large volume of concrete to be cast, the complex environment of the buried section and the underground environment of the lake bottom, the hydration heat and stress crack have been the main challenges of the under-lake tunnel engineering in crack control and waterproofing aspect. Simultaneously, with the development of big data, intelligent construction, information technology, and other techniques, these techniques are gradually applied to the whole life cycle of tunnel engineering including survey, design, construction, operation, and maintenance. The construction of the lake tunnel project is setting off a new round of technological innovation. This paper systematically summarizes the technical breakthroughs and application of technologies such as intelligent construction and information technology in the construction of under-lake tunnels in China, and puts forward reasonable suggestions on the key technologies of intelligent construction and operation maintenance for urban under-lake tunnel engineering.
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Peng, Cheng Hui, Chang Ming Wang, and Gang Cheng Wang. "Moraine Lake Outburst Simulation of Glacier Sliding and Risk Assessment." Advanced Materials Research 243-249 (May 2011): 3311–14. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.3311.
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Moraine Lake outburst is a common geological disaster in Tibet. Meltwater infiltrates into glacier through the cracks and lubricates it, increasing the instability of glacier. There is a close relationship between glacier landslide and Moraine Lake outburst. In order to explain it, we established the glacier sliding model, and analyzed the sliding characteristics. Then we discussed the link between glacier landslide and Moraine Lake outburst, and then proposed a quantitative expression. Finally we analyzed the glacier stability of Aya Moraine Lake and others, forecasted and evaluated the risk degree of Moraine Lake outburst. Field investigation conclusions are consistent with calculated results, that is to say, the calculated results are accurate and the predictions are reasonable.
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Grigoryeva, Elena, and Konstantin Lidin. "cracks, seams and borders." проект байкал 19, no. 74 (January 5, 2023): 121. http://dx.doi.org/10.51461/pb.74.20.
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Sometimes there are real cracks (and even gaps) between alternatives, and sometimes these borders look like seams joining the opposites. One of the peculiarities of architectural thinking is that it is like mosaic or patchwork. Scars and seams are inherent in architecture. Sometimes they are tried to be hidden, while sometimes to be aestheticized. How inclusive is the ‘patchwork’ of architectural thinking, or is it an exclusive stigma, a scar on the ‘profession’s skin’?Philosophical reflections on the semantic and philosophical-symbolic interpretation of the image of crack, rupture or gap in a broader context of cultural evolution, and, above all, in its current cultural-methodological meaning are presented by Leo Salmin and Petr Kapustin in their articles.Administrative boundaries can also turn into cracks. One of the most difficult tasks of urban planning and territorial management is to prevent ‘sprawling’ at the seams between regions. The border between the subjects adjacent to Lake Baikal runs directly along the water area of this glorious sea. And now, after the transfer of Transbaikalia to the Far Eastern Federal District, it is the border between the federal districts. But it is clear that the town planning documents should cover the whole lake, together with hundreds of rivers and streams flowing into it. Invisible seams prevent full comprehension of the whole complex. This is what Alexander Kolesnikov writes about.The seams of the borders within the Russian Empire were fantastically variable, including not only those of its provinces, but also of its cities. Such changes have occurred over the centuries for a variety of reasons, including political ones.The selection of materials in this section tells what is happening on the line of the collision of alternatives.
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Neubauer, Fernanda. "USE-ALTERATION ANALYSIS OF FIRE-CRACKED ROCKS." American Antiquity 83, no. 4 (October 2018): 681–700. http://dx.doi.org/10.1017/aaq.2018.33.
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Although it is now commonplace for archaeologists to study use-alteration patterns on ceramics, the same cannot be said of one of the most ubiquitous classes of hunter-gatherer artifacts, fire-cracked rocks (FCR). It can be shown, however, that many of the same methods and theories applied to the study of cooking ceramics are also relevant to the investigation of rocks used as heating elements. Because use alteration analyses of FCR are so scarce, I describe a range of attributes with the goal of helping researchers identify use alterations (e.g., sooting, reddening, various fracturing patterns) on lithic artifacts from sites worldwide and evaluate their potential function in various cultural practices. These attributes are also outlined in order to create a standardized terminology for describing FCR use-alteration patterns. I discuss my analysis of FCR from three Late Archaic sites (Duck Lake, 913, and 914) on Grand Island in Michigan's Upper Peninsula, followed by an interpretation of their cooking contexts, as a case study. The results indicate great intersite variability among FCR characteristics, cooking methods, and cooking facilities (earth oven, stone boiling, and rock griddle). This use alteration analysis can be applied in archaeological contexts worldwide where similar materials are recovered.
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Prassack, Kari Alyssa. "The effect of weathering on bird bone survivorship in modern and fossil saline-alkaline lake environments." Paleobiology 37, no. 4 (2011): 633–54. http://dx.doi.org/10.1666/10041.1.
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A modern Lesser Flamingo (Phoeniconaias minor) assemblage was collected along the shoreline of Lake Emakat, a saline-alkaline lake in northern Tanzania. Taphonomic analysis found the assemblage to be heavily weathered. This is likely due to the bone's heightened exposure to solar radiation and corrosive soil and water chemistries, as is expected to occur in such depositional environments.Analysis found that deep, wide, longitudinal cracks penetrate the medullar cavities of both weathered and unweathered long bones. The cause and taphonomic consequence of these cracks are addressed here, using data from Lake Emakat and from controlled studies. Results support repeated (episodic) submersion, followed by drying, as the causal mechanism behind thesewet-drycracks. Mineral salt uptake by bone may explain the early appearance and prevalence of these cracks in saline-alkaline lake settings, as compared to other depositional settings.The rate of weathering and incidence of wet-dry cracking varies significantly across limb elements. This difference correlates to element specific resistance properties to external loading forces. Heavy weathering weakens the structural integrity of bone and can accelerate its fragmentation. This can lead to bird bone loss in nearshore and ephemeral wetland settings, which may then affect resulting skeletal part, diversity, and richness profiles. Heavy weathering can therefore obscure important taphonomic and paleoecological information.The weathering data collected here are then applied to a fossil bird assemblage from the FLK Complex, (late Pliocene), Olduvai Gorge, in Tanzania. Results provide evidence for the effect of weathering on paleoecological and behavioral interpretations. Weathering should be considered when analyzing fossil bird assemblages.
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Robertson, Christopher G., Radek Stoček, Christian Kipscholl, and William V. Mars. "Characterizing the Intrinsic Strength (Fatigue Threshold) of Natural Rubber/Butadiene Rubber Blends." Tire Science and Technology 47, no. 4 (October 1, 2019): 292–307. http://dx.doi.org/10.2346/tire.19.170168.
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ABSTRACT Tires require rubber compounds capable of enduring more than 108 deformation cycles without developing cracks. One strategy for evaluating candidate compounds is to measure the intrinsic strength, which is also known as the fatigue threshold or endurance limit. The intrinsic strength is the residual strength remaining in the material after the strength-enhancing effects of energy dissipation in crack tip fields are removed. If loads stay always below the intrinsic strength (taking proper account of the possibility that the intrinsic strength may degrade with aging), then cracks cannot grow. Using the cutting protocol proposed originally by Lake and Yeoh, as implemented on a commercial intrinsic strength analyzer, the intrinsic strength is determined for a series of carbon black (CB) reinforced blends of natural rubber (NR) and butadiene rubber (BR) typical of tire applications. The intrinsic strength benefits of the blends over the neat NR and BR compounds are only observed after aging at temperatures in the range from 50 to 70 °C, thus providing fresh insights into the widespread durability success of CB-filled NR/BR blends in tire sidewall compounds and commercial truck tire treads.
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Liu, Shuli, Minfei Jian, Longyin Zhou, and Wenhua Li. "Distribution and characteristics of microplastics in the sediments of Poyang Lake, China." Water Science and Technology 79, no. 10 (May 15, 2019): 1868–77. http://dx.doi.org/10.2166/wst.2019.185.
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Abstract Microplastics are considered to be a widespread environmental contaminant, posing a serious threat to the aquatic environment. We addressed this issue based on field observations and laboratory analysis of samples from Poyang Lake. We collected sediment samples from 10 sites across Poyang Lake during 2017. Data were analyzed by one-way analysis of variance (ANOVA). Results showed that the abundance of microplastics ranged from 11 to 3,153 items/kg dw in the sediment samples. Except at Nanjishan, the amount of microplastics in different periods decreased in the order: December > April > July. Microplastics with a size <1 mm were the most abundant fraction in sediments, reaching over 50%. Observations under microscope revealed four types of microplastics in Poyang Lake: fragments, films, foams and fibers. Fragments were more common in sediments. Microplastics have complex surface topography, typically including rough surfaces, porous structures, cracks and extensive damage. Energy dispersive X-ray analysis indicated that most microplastics contained Si, Na, Ca, Cl and Al. Overall, the results provided strong evidence of high levels of microplastics in Poyang Lake, suggested that the microplastics pollution status in Poyang Lake should continue to be monitored.
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Mackay, J. Ross, and C. R. Burn. "The first 20 years (1978-1979 to 1998–1999) of ice-wedge growth at the Illisarvik experimental drained lake site, western Arctic coast, Canada." Canadian Journal of Earth Sciences 39, no. 1 (January 1, 2002): 95–111. http://dx.doi.org/10.1139/e01-048.
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In August 1978, a large tundra lake was drained to study the aggradation of permafrost into newly exposed lake-bottom sediments. Ice-wedge growth, which started in the first winter following drainage, had ceased in most of the lake bottom within about twelve years. The gradual cessation of thermal contraction cracking can be attributed to rapid vegetation growth, snow entrapment, an increase in winter ground temperatures, and a decrease in the linear coefficient of thermal contraction associated with freezethaw consolidation of the initially saturated lake-bottom sediments. The tilt and separation of markers in the active layer revealed gradual convergence towards the troughs even after ice-wedge growth had ceased. For the first few years the ice-wedge growth rate was up to 3 cm/a as determined by excavation, drilling, separation of the bottoms of benchmarks installed into permafrost, and divergence of free-floating inductance coils placed on the sides of ice wedges well below the bottom of the active layer. The vertical extent of most ice wedges was probably about 2 m, as deduced from the depths of ice-wedge cracks and the geometries of the wedge tops. Many thermal contraction cracks propagated upward to the ground surface from the tops of the ice wedges rather than downward from the ground surface. Small, upward facing, horizontal steps and vertical slickensided surfaces in permafrost on both sides of an excavated ice wedge near its top indicated that the adjacent permafrost had moved upward, relative to the wedge, from thermal expansion during the warming period.
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Kebede, Seifu, and Samson Zewdu. "Use of 222Rn and δ18O-δ2H Isotopes in Detecting the Origin of Water and in Quantifying Groundwater Inflow Rates in an Alarmingly Growing Lake, Ethiopia." Water 11, no. 12 (December 9, 2019): 2591. http://dx.doi.org/10.3390/w11122591.
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Dual Radon (222Rn) and δ18O-δ2H isotopes were utilized to (a) detect the origin of water, (b) pinpoint groundwater inflow zones and (c) determine rates of groundwater inflows in an expanding lake in central Ethiopia. The lake area expanded from 2 km2 to 50 km2 over the last 60 years, causing serious engineering and socio-economic challenge (inundation of urban utilities, irrigation farms, railways and roads; ecological changes in the lake; and threatening water salinization for water users downstream). Commensurate with the changes in volume, there was a change in salinity of the lake from a hypersaline (TDS 50 g/L) to a near freshwater (3 g/L) condition. 222Rn is powerful in pinpointing sites of groundwater inflows and determining groundwater inflow rates in lake systems with non-hydrologic steady-state conditions. The 222Rn method is complemented by the use of the stable isotopes of water (δ18O-δ2H pair). The δ18O-δ2H isotopes were used to discriminate the source of the water responsible for the expansion of the lake. The results show that the main source of water responsible for the expansion of the lake is the irrigation of excess water joining the lake through subsurface flow paths. The fast and voluminous flow is aided by a dense network of faults and by seismically induced modern ground-cracks that enhance the transmissivity of the aquifers to as high as 15,000 m2/day. The 222Rn mass balance shows the groundwater inflow rate is estimated at 4.6 m3/s. This is comparable with the 4.9 m3/s annual seepage loss from three large farms in the area. This work adds to the meager literature in the use of 222Rn in lake-groundwater interaction studies by demonstrating the capability of the method in addressing a practical engineering and socio-economic challenges.
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Dyer-Pietras, Kuwanna, and Kuwanna Dyer-Pietras. "Spatial and temporal cycle variations in the Eocene Lacustrine Green River Formation, Piceance Creek Basin, Colorado." Geosites 50 (September 1, 2022): 1–36. http://dx.doi.org/10.31711/ugap.v50i.113.
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Lithological cycles in the lacustrine Green River Formation of the Piceance Creek Basin, Colorado, vary spatially and temporally, and are challenging to correlate across the basin. In the center of the basin, lacustrine deposits contain bedded evaporites and kerogen-rich carbonate mudstone, whereas basin margin deposits contain alluvial sandstone, kerogen-poor mudstone, stromatolite, and mud cracks. Because coarsening upward cycles identified at the basin center differ significantly from cycles at the basin margin, exactly how cycle boundaries extend from one location in the basin to another is commonly unclear. In this investigation, eleven lithofacies are identified based on rock composition, sedimentary textures, physical sedimentary structures, biogenic structures, and chemical features. Lithofacies are grouped into four facies associations: (1) Alluvial Facies Association; (2) Shoreline Facies Association; (3) Shallow Lake Facies Association; and (4) Deep Lake Facies Association. Lithological cycles in the Green River Formation vary temporally and spatially, with each stratigraphic section preserving a record of deposition in a particular area of the basin as the Piceance lake evolved. To address the temporal and spatial variation of the cycles, multiple “type” cycles are described for each location in the study area. Facies associations and temporal stacking of cycles suggest that the Piceance lake was initially a deep, freshwater lake, following the Long Point transgression, as lake level rose above the Douglas Creek Arch to fill both the Uinta and Piceance Creek basins. Lake levels then stabilized but later began a period of increased fluctuation. Following basin closure, the Piceance lake became hypersaline under evaporative concentration conditions, precipitating nahcolite and halite at the basin center, with exposure of mudflats at the basin margin. The lake would remain this way until the Mahogany transgression deepened and diluted the lake. Together, facies associations and “type” cycles described in the Green River Formation lacustrine deposits reveal a record of lateral and vertical facies changes that occurred in the Piceance lake during its evolution.
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Lee, H. N., S. Jitprasithsiri, H. Lee, and R. G. Sorcic. "Development of Geographic Information System-Based Pavement Management System for Salt Lake City." Transportation Research Record: Journal of the Transportation Research Board 1524, no. 1 (January 1996): 16–24. http://dx.doi.org/10.1177/0361198196152400103.
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Over the past 3 years, a major effort has been made toward making a pavement management system (PMS) functional in Salt Lake City, Utah. As part of this effort, a geographic information system (GIS) was developed to enhance the existing PMS. The GIS-based PMS (G-PMS) developed for Salt Lake City is presented. G-PMS was written in Map-Basic, the programming language of MapInfo, to provide pavement engineers at Salt Lake City with customized menus and pavement management functions. The G-PMS reads in the unified crack indexes based on the digital image processing algorithm, recommends the most appropriate maintenance strategies, and displays those strategies on a digital map. It also provides the functions to report estimated costs for each maintenance activity and conduct financial planning. The design and function of G-PMS are discussed in detail. G-PMS is being implemented for the public works department of Salt Lake City.
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Zhang, Li, and Qiao. "Effect of Copper Tailing Content on Corrosion Resistance of Steel Reinforcement in a Salt Lake Environment." Materials 12, no. 19 (September 20, 2019): 3069. http://dx.doi.org/10.3390/ma12193069.
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With the increasing proportions of copper tailings of concrete in the Qinghai Salt Lake area of China, there arises the problem of corrosion of steel reinforcement in concrete structures. In this study, we determine the corrosion rate (CR), crack width, and corrosion potential of the steel reinforcement with copper tailing. This was achieved by conducting the constant-current accelerated corrosion test with different proportions of copper tailing in the brine environment of the Qinghai province. The results demonstrate that the corrosion potential (Ecorr) and the passivation area of the polarization curve decrease with the increase in the corrosion time, and the corrosion rate and crack width increase with the increase in the corrosion time. When the corrosion time is the same, the corrosion potential, crack width, and corrosion depth of the reinforcement decrease first and then increase with the increase in the copper tailing powder content. When the copper tailing powder content is 20%, the above parameters reach the minimum value. In the salt lake environment of Qinghai, China, the copper tailing powder content is recommended to be 20%.
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Navarro, Vicente, Marina Moya, Laura Asensio, and Juan Alonso. "Underwater Monitoring of the Cracks Found in Santos Morcillo Lake, Central Spain." Geotechnical Testing Journal 36, no. 1 (December 2012): 20120119. http://dx.doi.org/10.1520/gtj20120119.
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Klonowski, Elizabeth, Tim Lowenstein, Alan Carroll, M. Elliot Smith, Matteo Paperini, and Jeffrey Pietras. "Recurring lacustrine depositional successions in the Wilkins Peak Member, Green River Formation." Geosites 50 (September 1, 2022): 1–23. http://dx.doi.org/10.31711/ugap.v50i.116.
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Mineralogy, petrographic textures, and sedimentary structures from the world’s largest trona deposit, the Wilkins Peak Member (WPM) of the early Eocene Green River Formation (GRF), Bridger subbasin, Wyoming, provide key data about depositional conditions and paleoenvironments. The 250 m-long WPM interval in the Solvay S-34-1 drill core analyzed in this study contains a detailed record of sedimentation in the Bridger subbasin at the deepest area of a hydrologically-closed basin during peak Cenozoic atmospheric CO2 concentrations. Large accumulations of trona (Na3(HCO3)(CO3)·2H2O), shortite (Na2Ca2(CO3)3), northupite (Na3Mg (CO3)2Cl), and halite (NaCl; now replaced by trona), occur in the lower half of the WPM. Modern saline lake environments such as Lake Magadi, Kenya, and the Dead Sea, Israel-Jordan, are useful analogues for interpreting paleolake conditions associated with evaporite deposition in the Solvay S-34-1 core. Solvay saline lake deposits are organized into meter-scale shallowing-upward successions, beginning with (1) oil shale overlain by (2) trona, in places interbedded with oil shale, followed by (3) peloidal dolomite grainstone and/or silty dolomitic mudstone, and (4) massive mudstone with disruption features or desiccation cracks, and/or siliciclastic sandstone with ripple cross-stratification. Based on observations of modern hypersaline lake environments, WPM evaporite deposition at the basin depocenter is interpreted to be controlled by inflow water composition and volume, evaporative concentration, and seasonally-driven lake temperature fluctuations, resulting in recurrent patterns in evaporite mineralogies and textures.
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Duczmal-Czernikiewicz, Agata, Adam Choiński, Mariusz Ptak, and Andrzej Muszyński. "Mineralogy and deformation structures in components of clastic sediments from the Morasko meteorite lake (Poland)." Bulletin of Geography. Physical Geography Series 15, no. 1 (December 1, 2018): 91–100. http://dx.doi.org/10.2478/bgeo-2018-0018.
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Abstract The paper presents a mineralogical analysis of sediments of the biggest lake in the Morasko Meteorite Reserve (Poland). The lake is filled by phytogenic sediments at the top, while at the bottom there are Neogene clays. The main components are: clay minerals in fine fraction and quartz and feldspars in coarse sandy fractions. The presence of disturbed ferrous zones suggests the existence of a dynamic factor that caused deformations in the sediments. Cavities, crevices, cracks, and traces of parching or fragmentation of mineral material can be interpreted as deformations related to the impact of meteorite fragments in non-consolidated soft sediments in the Morasko meteorite nature reserve. Meteorite fragments that left numerous deformed structures were most probably consituted meteorite debris that originated from the fragmentation of the meteorite before its impact.
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Gradova, N. B., S. P. Sivkov, E. V. Agalakova, A. A. Belov, N. A. Suyasov, N. S. Khokhlachev, and V. I. Panfilov. "A Preparation based on Bacteria Isolated from Hypersaline Environments to Improve the Functional and Protective Characteristics of Concrete." Biotekhnologiya 36, no. 4 (2020): 21–28. http://dx.doi.org/10.21519/0234-2758-2020-36-4-21-28.
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Improving the strength and stability of cement-based structures in adverse environmental conditions with associated anthropogenic influences is possible through the development and implementation of nature-like and nature-friendly technologies. The ability of urobacteria to precipitate calcium carbonate can be useful in the manufacture of self-healing and reinforced concrete, in the crack healing and the restoration of concrete structures. Hypersaline environment is an ecological niche for search for microorganisms that are resistant to increased alkalinity, changing environmental conditions and stress. Screening of microorganisms allowed us to isolate the most active urobacteria, Lysinibacillus macroides and Bacillus licheniformis, from hypersaline lakes. The introduction of these microorganisms into the cement mixture significantly increased the strength of mortar specimens, reduced their porosity and capillary water absorption, which was associated with ongoing biocalcination. We studied the microstructure of spores of diatomite-immobilized bacteria and showed that this form provided long-term preservation of bacterial activity. A high activity of bacterial preparations in the healing of cement stone cracks was found. biomineralization, biocementation, extreme halophiles, crack healing, cement mortar, microbial concrete, urea hydrolysis. The work was supported by the D. Mendeleev University of Chemical Technology of Russia (Project no. 033-2018).
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Long, L. T., A. Kocaoglu, R. Hawman, and P. J. W. Gore. "The Norris Lake Earthquake Swarm of June Through September, 1993; Preliminary Findings." Seismological Research Letters 65, no. 2 (April 1, 1994): 167–71. http://dx.doi.org/10.1785/gssrl.65.2.167.
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Abstract During the summer of 1993, the residents in the Norris Lake community, Lithonia, Georgia, were bothered by an incessant swarm of earthquakes. The largest, a magnitude 2.7 on September 23, showed a normal aftershock decay and occurred after the main swarm. Over 10,000 earthquakes have been detected, of which perhaps 500 were felt. The earthquakes began June 8, 1993, with a 5-day swarm. The residents, accustomed to quarry explosions, suspected the quarries of irregular activities. To locate the source of the events, a visual recorder and a digital event recorder were placed in the epicentral area. Ten to 20 events were detected per day for the next three weeks. The swarm then escalated to a peak of over 100 per day by August 15, 1993. Activity following the peak died down to about 10 events per day. The magnitude 2.7 event of September 23 was followed by a normal aftershock sequence. The larger events were felt with intensity V within 2 km of their epicenter, and noticed (intensity II) to a distance of 15 km. Some incidents of cracked wallboard and foundations have been reported, but no significant damage has been documented. Preliminary locations, based on data from digital event recorders, suggest an average depth of 1.0 km. The hypocenters are in the Lithonia gneiss, a massive migmatite resistant to weathering and used locally as a building stone. The epicenters are 1 to 2 km south-southwest of the Norris Lake Community. The cause of the seismicity is not yet known. The earthquakes are characteristic of reservoir-induced earthquakes; however, Norris Lake is a small (96 acres), 2 to 5m deep recreational lake which has existed since the 1950s.
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Wei, Qixin, Xiaojun Yao, Hongfang Zhang, Hongyu Duan, Huian Jin, Jie Chen, and Juan Cao. "Analysis of the Variability and Influencing Factors of Ice Thickness during the Ablation Period in Qinghai Lake Using the GPR Ice Monitoring System." Remote Sensing 14, no. 10 (May 19, 2022): 2437. http://dx.doi.org/10.3390/rs14102437.
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As a reliable indicator of regional climate change, the growth and decline of lake ice thickness affect the regional intra–annual heat and energy balance. In this study, a ground-penetrating radar (GPR) ice monitoring system, located approximately 1.7 km west of Bird Island in Qinghai Lake, in the territory of Qinghai Province and located in northwest China, was designed to carry out continuous fixed–point observations of local ice thickness and meteorological elements from 7 to 24 March 2021. The characteristics of continuous daily changes in ice thickness during the ablation period of Qinghai Lake and their relationship with meteorological elements were analyzed. The results showed that the average daily ice thickness of Qinghai Lake increased and then decreased during the observation period, with an average ice thickness of 42.83 cm, an average daily ice thickness range of 39.35~46.15 cm, and a growth rate of 0.54 cm/day during 8–13 March 2021, with an ice melting rate of −0.61 cm/day during 14–24 March 2021. The daily ice thickness variations were divided into two phases, which were relatively stable before dawn and followed a decreasing, increasing, and then decreasing trend during 8–13 March 2021 and a decreasing, increasing (for several hours), and then decreasing trend during 14–24 March 2021. There was a significant positive correlation (R = 0.745, p < 0.01) between near-surface air temperature and ice surface temperature during the observation period, but a significant negative correlation (R = −0.93, p < 0.05) between the average daily ice thickness and cumulative temperature of the ice surface. Temperature was the dominant factor affecting lake ice thickness, as compared to near-surface air humidity, wind speed, and illuminance. However, a sudden increase in wind speed have also played an important role at certain periods. A large number of cracks appeared on the ice surface on 26 March 2021, which, combined with the forces of wind speed, wind direction, and temperature, contributed to the rapid melt of the lake ice. This study filled the gap in situ measurement data on the continuous ice thickness variability during the ablation period in Qinghai Lake. It provided scientific support for the further study of lake ice on the Qinghai–Tibet Plateau (QTP).
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LISTER, L. A., and C. D. SECREST. "Giant Desiccation Cracks and Differential Surface Subsidence, Red Lake Playa, Mohave County, Arizona." Environmental & Engineering Geoscience xxii, no. 3 (August 1, 1985): 299–314. http://dx.doi.org/10.2113/gseegeosci.xxii.3.299.
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Hartley, Adrian, Bartosz Kurjanski, Jessica Pugsley, and Joseph Armstrong. "Ice-rafting in lakes in the early Neoproterozoic: dropstones in the Diabaig Formation, Torridon Group, NW Scotland." Scottish Journal of Geology 56, no. 1 (December 18, 2019): 47–53. http://dx.doi.org/10.1144/sjg2019-017.
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A dropstone horizon is described from lake deposits in a palaeo-valley from the c. 1000 Ma Diabaig Formation, Torridon Group, NW Scotland. Dropstones occur in wave-rippled, fine-grained sandstones and siltstones that contain desiccation and syneresis cracks indicative of fluctuating lake levels. Five locally derived dropstones occur at the same horizon over lateral distance of 250 m and display clear evidence of deflection and penetration of laminae at the base, with thinning, onlap and draping of laminae on to clast margins and tops. Mechanisms of dropstone formation are discussed, with ice-rafting considered the most likely explanation. It is suggested that rafting was promoted by cold winters at 35° S in the early Neoproterozoic, possibly in an upland setting. Interpretation of the dropstones as ice-rafted debris provides the first physical record of evidence for ice at the Earth's surface during the late Mesoproterozoic to early Neoproterozoic.
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McKee, R. H., and S. C. Lewis. "Evaluation of the dermal carcinogenic potential of liquids produced from the Cold Lake heavy oil deposits of Northeast Alberta." Canadian Journal of Physiology and Pharmacology 65, no. 8 (August 1, 1987): 1793–97. http://dx.doi.org/10.1139/y87-279.
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This study assessed the dermal carcinogenic potential of raw bitumen derived from the Cold Lake Oil Sands deposit (located in Northeast Alberta, Canada) and two liquids which were under evaluation as part of a process to refine the crude bitumen at the Cold Lake site. The crude bitumen was dermally carcinogenic, inducing tumors in 26% of the treated animals with a median latency of 106 weeks. This response was significantly greater than the tumor yield previously reported for a raw bitumen derived from Athabasca tar sands by the Syncrude process, but was not substantially different from the carcinogenic potential of two crude petroleum oils. The GO-FINING product, a high boiling (259–519 °C), catalytically cracked gas oil was a relatively potent dermal carcinogen, inducing tumors in 86% of the treated animals with a median latency of 46 weeks. This result is consistent with the fact that the GO-FINING product contained appreciable levels of high boiling aromatic compounds. The HYCRACKING product, a high boiling (102–498 °C), severely hydroprocessed liquid was noncarcinogenic. This result was also consistent with the compositional data; the high boiling components were predominantly saturated species. Thus the carcinogenic properties of the liquid products prepared by these two processes were as predicted from the compositional information.
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Rapp, George (Rip), Sanda Balescu, and Michel Lamothe. "The Identification of Granitic Fire-Cracked Rocks Using Luminescence of Alkali Feldspars." American Antiquity 64, no. 1 (January 1999): 71–78. http://dx.doi.org/10.2307/2694346.
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The question of Fire-Cracked Rock (FCR) in Woodland contexts has become an important and controversial topic in Western Great Lakes archaeology. There are no clear and widely accepted criteria for distinguishing FCR when the rocks show no observable characteristics associated with fire (heating and cooling). To help overcome this shortcoming, we analyzed both the thermoluminescence (TL) and the optically stimulated luminescence (OSL) of alkali feldspar grains from a series of six samples of FCR from the Hannaford site in northern Minnesota. A geologic unheated specimen from the same geographic area was used as a control sample. A comparison of the luminescence (TL and OSL) intensities of both natural and natural plus artificial dose signals allowed us to demonstrate that the six selected samples of FCR had been effectively heated at the time of archaeological settlement. The good agreement between the TL and OSL results suggests that the OSL method is a viable alternative to TL for the identification of FCR. The OSL method requires less material, can be applied to a large number of samples, and is more cost-effective.
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Zhang, Xin, and Yu Long Li. "Simulation of Pylon Emergency Break-Away of Large Commercial Aircraft." Key Engineering Materials 525-526 (November 2012): 257–60. http://dx.doi.org/10.4028/www.scientific.net/kem.525-526.257.
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Most large commercial aircraft engines are hanged below wings. When the aircraft makes an emergent landing process, at the same time, the landing gear cannot work or the centrifugal force becomes unbalanced as the fan blades fly away. In order to ensure safe landing, overall tank crack and fuel leak should be avoid at the crack area. Access to a large number of emergent landing accidents, emergency break-away is essential. In this paper, the break-away position, which locates between the pylon and the wing, is mainly considered. We choose true size in the models of wing, pylon and engine. High strength steel is employed for the bolts which connect pylon and wing. Earth and lake are employed concrete and pure water respectively. SPH method is applied in the case that the aircraft lands on the lake. Whats more, different landing cases have been analyzed. By constantly adjusting the size of pins, a set of conclusions of the emergent landing problem are obtained in the simulation process. The locus of centroid of engine and pylon is obtained, and then the condition which may achieve safe flight and avoid the secondary damage to wings can be chosen, from which we can provide reasonable designing strength of the wing box and accordingly provide reference for the design of aircraft structure.
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Fitria, Nurul. "PENGGUNAAN MEDIA “CRACK THE CIRCUIT” UNTUK MENINGKATKAN HASIL BELAJAR SISWA PADA MATERI RANGKAIAN LISTRIK." JIRA: Jurnal Inovasi dan Riset Akademik 2, no. 1 (January 15, 2021): 9–15. http://dx.doi.org/10.47387/jira.v2i1.68.
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Penelitian ini didasari hasil belajar siswa yang cenderung mengalami penurunan selama daring khususnya pada rangkaian listrik kelas 9 C SMP Muh PK pada bulan September 2020. Salah satu penyebabnya sebagian peserta didik kurang mampu memahami dan menganalisis rangkaian listrik. Dari permasalahan tersebut, maka perlu diadakannya penelitian tindakan kelas dimana peneliti mencoba menerapkan penggunaan media Crack The Circuit. Media Crack The Circuit diharapkan dapat meningkatkan hasil belajar IPA pada rangkaian listrik. Metode penelitian ini menggunakan dua siklus dengan instrument yang digunakan meliputi evaluasi online, pengamatan dan pengarsipan data dengan 30 siswa yang terdiri 12 laki – laki dan 18 perempuan. Berdasarkan hasil uji instrument diperoleh data nilai rata – rata siswa pada siklus I yaitu 75,67 dengan 16 anak yang tuntas, sedangkan siklus II nilai rata – rata 85,67 dengan siswa yang tuntas 30 anak. Oleh sebab itu, dapat dikatakan bahwa penggunaan media Crack The Circuit dapat meningkatkan hasil belajar siswa pada materi rangkaian listrik.
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Kirkbride, Martin P., and Charles R. Warren. "Calving processes at a grounded ice cliff." Annals of Glaciology 24 (1997): 116–21. http://dx.doi.org/10.3189/s0260305500012039.
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Repeat photographs and field survey reveal the mechanism of short-term ice-cliff evolution at Maud Glacier, a temperate lake-calving glacier in New Zealand. Calving is cyclic, each cycle involving four stages: (1) waterline melting and collapse of the roof of a sub-horizontal notch at the cliff foot; (2) calving of ice flakes from the cliff face leading to a growing overhang from the waterline upwards, and crack propagation from the glacier surface; (3) large but infrequent calving of slabs in response to the developing overhang, returning the cliff to an “initial” vertical profile; (4) rare subaqueous calving ofa submerged ice foot. Results indicate that the rate-controlling process is the speed of waterline melting, and that calving rate is independent of water depth (at least at time-scales of weeks to months). Slowly calving lake-terminating glaciers have mass balances more negative than land-terminating glaciers, but nevertheless advance and retreat in response to mass-balance driven changes in ice velocity.
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Kirkbride, Martin P., and Charles R. Warren. "Calving processes at a grounded ice cliff." Annals of Glaciology 24 (1997): 116–21. http://dx.doi.org/10.1017/s0260305500012039.
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Repeat photographs and field survey reveal the mechanism of short-term ice-cliff evolution at Maud Glacier, a temperate lake-calving glacier in New Zealand. Calving is cyclic, each cycle involving four stages: (1) waterline melting and collapse of the roof of a sub-horizontal notch at the cliff foot; (2) calving of ice flakes from the cliff face leading to a growing overhang from the waterline upwards, and crack propagation from the glacier surface; (3) large but infrequent calving of slabs in response to the developing overhang, returning the cliff to an “initial” vertical profile; (4) rare subaqueous calving ofa submerged ice foot. Results indicate that the rate-controlling process is the speed of waterline melting, and that calving rate is independent of water depth (at least at time-scales of weeks to months). Slowly calving lake-terminating glaciers have mass balances more negative than land-terminating glaciers, but nevertheless advance and retreat in response to mass-balance driven changes in ice velocity.
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Stavropoulou, V., D. Giannopoulos, E. Sokos, K. I. Konstantinou, and G. A. Tselentis. "SHEAR WAVE ANISOTROPY MEASUREMENTS ABOVE SMALL EARTHQUAKES IN TRICHONIS LAKE, GREECE." Bulletin of the Geological Society of Greece 50, no. 3 (July 27, 2017): 1241. http://dx.doi.org/10.12681/bgsg.11830.
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On April 2007, an earthquake swarm occurred in the vicinity of Trichonis Lake, western Greece. The seismic activity started on April 10th, 2007 after the occurrence of three moderate size earthquakes MW 5.0-5.2. We performed shear wave splitting measurements on seismic events recorded during the first week of the seismic activity by a portable network of 8 stations that was installed in the area by the University of Patras Seismological Laboratory. We were able to take measurements from 5 stations as the seismicity was concentrated mostly at the eastern part of the lake. Two splitting parameters were measured through the data processing, the time-delays between the fast and slow shear wave components and the polarization directions of the fast components. In general, the data analysis revealed the presence of shear wave anisotropy in the study area. The average value of normalized time-delays was calculated at 6.9 ±1.1 ms/km while the fast polarization directions had an average of 130o ±14o. The mean fast polarization directions were consistent with what is expected concerning the local stress field, as it was sub-parallel to the strike of the major faults at the eastern part of the lake and almost perpendicular to the direction of extension. Therefore, the findings can be interpreted by an anisotropic volume of stress-aligned micro-cracks within the upper crust according to the extensive dilatancy anisotropy model.
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Neubauer, Fernanda. "Late archaic hunter-gatherer lithic technology and function (chipped stone, ground stone, and fire-cracked rock)." Revista de Arqueologia 30, no. 1 (July 3, 2017): 260–62. http://dx.doi.org/10.24885/sab.v30i1.514.
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This doctoral research highlights the complicated trajectories of hunter-gatherers by offering a case study from an understudied but rich hunter-gatherer landscape, the Late Archaic period (c. 5,000-2,000 BP) on Grand Island in Michigan’s Upper Peninsula, United States. Although there is a paucity of Late Archaic period archaeological data from the mainland of the Upper Peninsula, recent excavations by the Grand Island Archaeological Program (GIAP), directed by James M. Skibo (Illinois State University) and co-directed by Eric C. Drake (Hiawatha National Forest), have yielded a sizable body of evidence of Late Archaic occupations on Grand Island. I have been a staff member and collaborator with GIAP since 2007, conducting research, laboratory work, and co-directing excavations. My analysis of 39,186 lithics from five sites on the island more than doubles the current number of c. 32,000 lithics analyzed in the entire southern shore of Lake Superior in Michigan’s Upper Peninsula from dated Late Archaic sites. Similarly, the 495 faunal remains identified and analyzed by Terrance Martin and Elizabeth Scott for this dissertation also more than doubles the total 296 pieces of animal bones analyzed from dated Late Archaic sites of the Upper Peninsula. In addition, in contrast to those sites, where no complete and finished projectile points have been recovered in context, GIAP have identified a total of five projectile points. These points may contribute to data on diagnostic artifact types in the Upper Peninsula, which is currently almost non-existent, and to our general understanding of exchange practices and social interactions.
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Butnariu, Ioan. "Restaurarea unei picturi pe carton." Anuarul Muzeului Etnograif al Transilvaniei 30 (December 20, 2016): 293–301. http://dx.doi.org/10.47802/amet.2016.30.16.
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The work that is subject to the restoration interventions presented in this article is a painting done in oil colors on cardboard. The subject of this painting is represented by a landscape with an isolated castle on a lake island, surrounded by mountains. The painting’s degradations cumulated multiple cracks and gap areas affecting the painting and the primer layers, together with areas of damage due to the painting’s exposure to excessive heat. The restoration operations (consolidation of the painting layers, the cleaning of the surface, filling the gaps in the primer and the chromatic integration of painting lacunae) have rendered the painting its original image.
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Stein, N., J. P. Grotzinger, J. Schieber, N. Mangold, B. Hallet, H. Newsom, K. M. Stack, et al. "Desiccation cracks provide evidence of lake drying on Mars, Sutton Island member, Murray formation, Gale Crater." Geology 46, no. 6 (April 16, 2018): 515–18. http://dx.doi.org/10.1130/g40005.1.
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Shen, Zhongwei, Jianbao Liu, Chengling Xie, Xiaosen Zhang, and Fahu Chen. "An environmental perturbation at AD 600 and subsequent human impacts recorded by multi-proxy records from the sediments of Lake Mayinghai, North China." Holocene 28, no. 12 (September 10, 2018): 1870–80. http://dx.doi.org/10.1177/0959683618798159.
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Modern observations indicate that a dramatic increase in the intensity of human activity is the main cause of environmental degradation. However, the timing of the onset of significant human impacts on regional environments during the historical period is unclear. In this study, an AMS 14C-dated 878-cm-long sediment core (MYH14B), from Lake Mayinghai in the farming-pastoral ecotone of northern China, was used to study the long-term relationship between the ecological environment and human activity. The area is characterized by a fragile ecological system and is sensitive to environmental change and human activity. We found evidence for abrupt sedimentary changes beginning around AD 600, revealed by the increased (decreased) content of exogenous (endogenous) elements, a decrease in grain size and the appearance of quartz particles with V-shaped percussion cracks. This evidence indicates an abrupt increase in sediments transported by surface run-off and that a large amount of freshwater was injected into the lake. The climate was stable at the time and therefore, combined with historical documentary evidence, we attribute this event to the excavation of a river channel flowing into the lake, in association with the construction of nearby Fenyang Palace by Emperor Yang during the Sui Dynasty. Subsequently, the content of exogenous elements in the sediments was significantly positively correlated with the intensity of deforestation, cultivation and grazing, indicating that these elements can be used as a proxy of the intensity of human activity. The variation of this proxy demonstrates that intensified human activity occurred during AD 600– 1100 and after AD 1350, and that human activity weakened during AD 1100–1350, which is supported by evidence from historical accounts and changes in the population size of Shanxi Province. Overall, our findings reveal a substantial conflict between human activity and environmental stability in the farming-pastoral ecotone of northern China during the Sui Dynasty (AD ~600). In addition, the sensitivity of the lake response to human activity revealed in this study highlights the importance of further paleolimnological studies in the region.
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Venslavsky, V., А. Orlov, and Yu Kharin. "Radiothermal radiation of the ice cover of the Arakhley lake as a geo-indicator of changes in a water body." Transbaikal State University Journal 26, no. 7 (2020): 6–16. http://dx.doi.org/10.21209/2227-9245-2020-26-7-6-16.
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The object of this study was the ecosystem of a water body; the subject was the radio-thermal radiation of the ice cover as a geo-indicator of changes in the ecological state of the Lake Arakhley. On the basis of a systematic approach, the work assessed the contribution of the seasonal variability of the properties of the ice cover to the intensity of radio-thermal radiation as a geo-indicator of the ecological system. At present, the influence of the ice cover deformation during the crack formation period on the intensity of radio-thermal radiation has not been sufficiently studied, which determined the relevance of an experimental study for use in problems of assessing anthropogenic factors of influence. The aim of the study was to measure the seasonal variability of the intensity of radio-thermal radiation as a background geo-indicator of the temperature regime and deformation of the ice cover during the crack formation period in the absence of direct anthropogenic factors. In January-March 2020, remote radio-physical methods were used to study the intensity of radio-thermal radiation of the microwave range for the test area of the ice cover of the Lake Arakhley during synchronous contact measurements of deformation and temperature in a niche at a depth of 40 cm from the surface. According to the data obtained, the reaction of the deformation sensor signal to daily temperature variations with a time lag of 1…3 hours was recorded. According to the results of the study, the correlation coefficient of the data of the ice deformation channel and the intensity of radio-thermal radiation in the range of 8…14 mm exceeded ± 0.7 (with a window of 1000 s), with the data of the temperature sensor in most areas exceeded ± 0.9. This proves the relationship between the temperature and deformation of the ice surface with the intensity of radio-thermal radiation, as a seasonal geo-indicator in determining the ecological state of the lake. The increments in the brightness temperature during the period of increased crack formation in the 14 mm channel, with a significant correlation with the deformation data, were about 3…6 K, which can also serve as a geo-indicator of seasonal changes in the properties of the ice cover. The results of the study were obtained in the absence of direct anthropogenic factors and are background geoindicators of the seasonal state of the ice cover during the period of temperature and dynamic loads during deformation and cracking, and in the future will be used in practice for correction in assessing the impact of anthropogenic factors
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Pratt, Brian R. "Desiccation cracks provide evidence of lake drying on Mars, Sutton Island member, Murray formation, Gale Crater: COMMENT." Geology 46, no. 8 (August 1, 2018): e449-e449. http://dx.doi.org/10.1130/g45084c.1.
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Stein, N., J. P. Grotzinger, J. Schieber, N. Mangold, B. Hallet, D. Y. Sumner, and C. Fedo. "Desiccation cracks provide evidence of lake drying on Mars, Sutton Island member, Murray formation, Gale crater: REPLY." Geology 46, no. 8 (August 1, 2018): e450-e450. http://dx.doi.org/10.1130/g45237y.1.
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Narasimharao, Jonnadula. "Dam Gate Control System using IOT." International Journal for Research in Applied Science and Engineering Technology 10, no. 6 (June 30, 2022): 2258–63. http://dx.doi.org/10.22214/ijraset.2022.44270.
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Abstract: Dams are in the main used for producing hydroelectricity and for irrigation purposes. This utilization has resulted within the construction of a variety of dams in potential areas over the years. As there are plenty of risk factors related to the existence of those dams, it’s became the necessity to develop a correct automatic monitoring system regarding the opening of the dam gates thereby managing a system for maintaining a secure water level in dams. Mismanagement of dams can also bring about manmade disasters. The dams that are present now are monitored and controlled manually. This ends up in pause in deciding. The proposed system involves real-time monitoring of water levels of the dam. Water levels may also range because of drastic adjustments in water levels of linked rivers of lakes, or because of the immoderate rainfall withinside the catchment area. The proposed system is an IoT system which is able to monitor and send real time parameters associated with Dam. The system also includes features like SMS alerts to the people of the locality and higher authorities, live display of water level and also the early-stage crack identification so as to scale back the risks of cracks which can lead to dam failure.
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Kołodziej, Krzysztof, Lesław Bichajło, and Tomasz Siwowski. "Experimental Study on Physical and Rheological Properties of Trinidad Lake Asphalt Modified Binder." Applied Sciences 11, no. 6 (March 21, 2021): 2796. http://dx.doi.org/10.3390/app11062796.
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Mastic asphalt (MA) has been recognized as one of the most deformation-resistant and thus durable materials for bridge pavement. The performance properties of MA are highly dependent on the physical and rheological properties of the binder applied in the MA mixture. To modify the binder properties to obtain the expected performance of the MA mixture, Trinidad Lake Asphalt (TLA) is often applied. In this study, the TLA-modified binders to be used in mastic asphalt bridge pavement systems were evaluated to develop the optimum material combination using conventional and performance-related testing. Physical and rheological tests were carried out on TLA-modified binders with the different modifier content in the range of 10–50% on a weight basis. The tests revealed that the TLA modifier addition to the 35/50 base bitumen should be close to the value of 20%. Higher concentrations of TLA may make the binder very stiff and could induce low-temperature cracks in mastic asphalt.
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Beisel, A. L., O. B. Kuzmina, E. S. Sobolev, and P. A. Yan. "New data on the problem of the origin of Griva and Lake landscapes in the south of Western Siberia." Interexpo GEO-Siberia 2, no. 1 (May 18, 2022): 56–62. http://dx.doi.org/10.33764/2618-981x-2022-2-1-56-62.
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The characteristic of the upper part of the borehole 486 drilled in 1981 on the Tyumensky Peninsula, located in the center of the Chany Reaches agglomeration is given. The main feature of the section is the presence of a horizon of large frost cracks in the roof of clays of the Lower Pliocene Novostanichnaya Formation, on which the upper Quaternary cover of Griva deposits occurs. The nature of the filling of cracks by the sediments of the overlying layer indicates that they were constantly filled with ice, which had already melted under the influence of the Grosswald Flow. This horizon is important for the reconstruction of the paleoclimate and paleogeography of the region. For the first time, data of palynological study of sediments of a typical Griva in the south of Western Siberia on the example of a section on the Cape Kazantsevsky Peninsula (the northern part of Lake Chany) are presented. Sediments contain pollen of woody and herbaceous plants, single spores of mosses and ferns, as well as microphytoplankton. The presence of cells of colonial algae of the genus Pediastrum suggests the accumulation of sediments in lacustrine conditions.
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Alley, Richard B., Todd K. Dupont, Byron R. Parizek, and Sridhar Anandakrishnan. "Access of surface meltwater to beds of sub-freezing glaciers: preliminary insights." Annals of Glaciology 40 (2005): 8–14. http://dx.doi.org/10.3189/172756405781813483.
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AbstractSufficiently deep water-filled fractures can penetrate even cold ice-sheet ice, but glaciogenic stresses are typically smaller than needed to propagate water-filled fractures that are less than a few tens of meters deep, as shown by our simplified analytical treatment based on analogous models of magmatic processes. However, water-filled fractures are inferred to reach the bed of Greenland through >1 km of ice and then collapse to form moulins, which are observed. Supraglacial lakes appear especially important among possible crack ‘nucleation’ mechanisms, because lakes can warm ice, supply water, and increase the pressure driving water flow and ice cracking.
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Gottschall, Kristina. "‘Jesus! A Geriatric — That's All I Need!’: Learning to Come of Age with/in Popular Australian Film." Global Studies of Childhood 1, no. 4 (January 1, 2011): 332–42. http://dx.doi.org/10.2304/gsch.2011.1.4.332.
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Popular film texts are powerful means by which Western societies construct, maintain, protect and challenge concepts of childhood and youth-hood. As a context where audiences learn about the self, their culture, and their place within it, popular film is understood here as pedagogic, that is, as a space where key lessons about the formation of subjecthood might take place, and at what costs. This article takes into account scholarship on popular culture as pedagogy, challenging narrow notions of popular film as a simple transmission of knowledge. Focused on how pedagogies might be at work, this article explores the use of humour, repetition, otherness, becoming and sentimentality within a selection of Australian films, and how they orientate audiences towards knowing the youth subject in particular ways. Questions of generation and how it is constructed as a commonsense battle between ‘young’ and ‘old’ are considered through the coming of age films, The Rage in Placid Lake (2003), Hey Hey It's Esther Blueburger (2008), Crackers (1998) and Spider & Rose (1994).