scholarly journals Monitoring and simulation of hydrothermal conditions indicating the deteriorating stability of a perennially frozen moraine dam in the Himalayas

2018 ◽  
Vol 64 (245) ◽  
pp. 407-416 ◽  
Author(s):  
XIN WANG ◽  
CHENGDE YANG ◽  
YANLIN ZHANG ◽  
KAILGUO CHAI ◽  
SHIYIN LIU ◽  
...  
Keyword(s):  
Mean Annual Temperature ◽  
Hydrothermal Conditions ◽  
Annual Average ◽  
Freezing Depth ◽  
Thawing Depth ◽  
Different Depths ◽  
Yearly Maximum ◽  
The Stability ◽  
Permafrost Thawing ◽  
Observation Period

ABSTRACTThermal and hydrological dynamics and their impacts on the stability of a moraine dam were analyzed and simulated for the Longbasaba Lake in the Himalaya, based on soil temperature, moisture and heat flux data observed at different depths in the dam from 2012 to 2016. Annual average heat income is greater than heat expenditure on the dam surface. The mean annual temperature at observed the depths of 0–150 cm is >0°C, although the average annual air temperature was −3.6°C over the dam, indicating a relatively larger temperature difference between moraine dam and air. The volumetric soil moisture content is relatively low with an annual average of 5%, peaking after the snow cover melting and active layer thawing. Simulation results indicate that the average yearly maximum thawing depth has been ~0.3 m deeper than the average yearly maximum freezing depth during the observation period. In the past 55 years, the yearly maximum thawing depth has increased, while yearly maximum freezing depth has decreased, implying that the permafrost in the dam has been deteriorating. The annual surplus heat and increasing permafrost thawing depth will result in further deterioration of permafrost and melting of buried ice in the dam, thereby decreasing its stability.

The Effect of Cutoffs on the Uplift Pressure Beneath the Hydraulic Structures Floor

2018 ◽  
Vol 6 (3) ◽  
pp. 20-28
Author(s):  
Faisal Al Tabatabaie ◽  
Dhabia Sabeeh Al Waily
Keyword(s):  
Potential Energy ◽  
Hydraulic Structure ◽  
Hydraulic Structures ◽  
Outer Face ◽  
Analogue Model ◽  
Electrical Analogue ◽  
Uplift Pressure ◽  
Different Depths ◽  
The Stability ◽  
Critical Sections

The use of cutoffs underneath the hydraulic structures is considered a safe solution to ensure the stability of hydraulic structure against uplift pressure and piping phenomenon in addition to the sliding and overturning forces of the water. These cutoffs are used at critical sections underneath the floor of hydraulic structure to substitute with their depths the horizontal lengths of the creep line of the hydraulic structure base. In this paper, the experimental method- by using electrical analogue model- was carried out to plot the flow net and study the efficiency of the front and rear faces of the cutoffs for dissipating the potential energy of the percolating water underneath the floor of hydraulic structure. An electrical analogue model which was used in this study consists of twenty five models with different depths of upstream and downstream cutoffs. After plotting the flow net for all models, it is concluded that the efficiency of the inner sides are less than that of the outer sides which were investigated before in this topic of this work that both faces reduction values in the uplift pressure are considered the same, where the efficiency of the outer face of upstream cutoff is (70.35) % and for the inner face is (29.64)%, while for the downstream cutoff the efficiency for the outer face is (76.21)% and for the inner face is (23.79)% .

scholarly journals Investigation of Hydrothermally Stressed Silicone Rubber/Silica Micro and Nanocomposite for the Coating High Voltage Insulation Applications

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3567
Author(s):  
Faiza Faiza ◽  
Abraiz Khattak ◽  
Safi Ullah Butt ◽  
Kashif Imran ◽  
Abasin Ulasyar ◽  
...  
Keyword(s):  
Silicone Rubber ◽  
Structural Changes ◽  
Polymer Chains ◽  
Hydrothermal Conditions ◽  
Silica Filler ◽  
Before And After ◽  
Aging Conditions ◽  
The Stability ◽  
Micro Silica ◽  
Applied Stresses

Silicone rubber is a promising insulating material that has been performing well for different insulating and dielectric applications. However, in outdoor applications, environmental stresses cause structural and surface degradations that diminish its insulating properties. This effect of degradation can be reduced with the addition of a suitable filler to the polymer chains. For the investigation of structural changes and hydrophobicity four different systems were fabricated, including neat silicone rubber, a micro composite (with 15% micro-silica filler), and nanocomposites (with 2.5% and 5% nanosilica filler) by subjecting them to various hydrothermal conditions. In general, remarkable results were obtained by the addition of fillers. However, nanocomposites showed the best resistance against the applied stresses. In comparison to neat silicone rubber, the stability of the structure and hydrophobic behavior was better for micro-silica, which was further enhanced in the case of nanocomposites. The inclusion of 5% nanosilica showed the best results before and after applying aging conditions.

scholarly journals Experimentation of grapevine cultivation in organic system, on five different Romanian vineyards

2016 ◽  
Vol 73 (2) ◽  
pp. 175
Author(s):  
Aurora Maria Ranca ◽  
Victoria Artem ◽  
Ionica Dina ◽  
Liliana Parcalabu ◽  
Maria Iliescu ◽  
...  
Keyword(s):  
Cynodon Dactylon ◽  
Climatic Factors ◽  
Growing Season ◽  
Lobesia Botrana ◽  
Amaranthus Retroflexus ◽  
Mean Annual Temperature ◽  
Stellaria Media ◽  
Annual Average ◽  
Organic System ◽  
Polygonum Aviculare

In five Romanian vineyards, in 2013-2014 period was experimented organic system growing on  grape varieties for wine representative for each area, here are applied organic growing technology in parallel with the conventional (control). White varieties studied are: Chardonnay (Murfatlar and Valea Calugareasca), Sauvignon blanc and Muscat Ottonel(Tarnave), Feteasca regala (Tarnave, Bujoru and Copou-Iasi). Red varieties are Cabernet Sauvignon (Murfatlar and Valea Calugareasca) and Merlot (Bujoru).Concerning evolution of main climatic factors for the years 2013-2014 it is show that the annual average air temperature increase compared with the average of the years 1991-2010; is observed an increasing in mean annual temperature, mean temperature during the growing season and the value of sum of sunshine hours. The water regime was kept constant, registering values close to the annual average, both during the growing season and at entire year. The weeds spectrum is represented both by dicotyledonous as knotweed (Polygonum aviculare), Veronica (Stellaria media), news (Amaranthus retroflexus), bindweed (Convolvurus arvensis) and monocotyledonous as grass thick (Cynodon dactylon).Concerning the phytosanitary status, at Murfatlar were registered problems with oidium attack, with all main disease at Dealu Mare and with downy mildew at Bujoru. In all areas the pest has been found are: grape mouth (Lobesia botrana) and spiders (Tetranichus sp.). Schemes of treatments focused generally on substances bassed on copper and sulfur to combat diseases and for pests have been used pheromonal traps or other certified organic products.The grapes harvest was lower in organic plots with till 25%; their quality being close at both growing variants.

Deformation and Failure Characteristics of Embankment upon the Slope in Permafrost Area under Different Foundation Slope

2013 ◽  
Vol 353-356 ◽  
pp. 905-910
Author(s):  
Qian Su ◽  
Jun Jie Huang ◽  
Bao Liu ◽  
Yu Jie Li
Keyword(s):  
Failure Modes ◽  
Centrifuge Modeling ◽  
Experimental Conditions ◽  
Soil Layers ◽  
Deformation And Failure ◽  
Geotechnical Centrifuge ◽  
Gravity Load ◽  
Unstable Failure ◽  
Thawing Depth ◽  
The Stability

To investigate the effect of foundation slope on stability of embankment upon the slope in permafrost area, 3 groups of model tests with different foundation slope are designed using the mechanical similarity based on geotechnical centrifuge modeling, when the freezing-thawing depth of the embankment reaches the greatest. The results show that: (1) The foundation slope has effect on the stability of the embankment. The deformation mainly concentrates on the soil layers above the freezing-thawing interface, and the deformation mutation point takes place at the freezing-thawing interface. (2) According to fracture characteristics and failure severity of the embankment, failure modes can be divided into the cracking failure in shallow layer and in deep layer. (3) The cause of unstable failure is the deficiency of shear resistance strength of the weak belt, the soil layers above the freezing-thawing interface slips along the freezing-thawing interface under gravity load. (4) Under the experimental conditions, the critical value of the foundation slope influencing on the stability of the embankment is about 1:6 when the height of the slope embankment is 5.0 m.

Mineral Redox Buffers and The Stability of Organic Compounds Under Hydrothermal Conditions

1996 ◽  
Vol 432 ◽  
Author(s):  
J. S. Seewald
Keyword(s):  
Organic Compounds ◽  
Active Species ◽  
Hydrothermal Systems ◽  
Hydrothermal Conditions ◽  
Sulfur Species ◽  
Sedimentary Environments ◽  
Mineral Assemblages ◽  
Catalytically Active ◽  
Chemical Conditions ◽  
The Stability

AbstractOrganic compounds play an integral role in numerous geochemical process in subsurface environments. To evaluate factors that regulate the stability of ethane, ethene, propane, and propene in hydrothermal systems a series of experiments were conducted at 300 to 325°C and 350 bars. The experiments contained the mineral assemblages pyrite-pyrrhotite-magnetite, hematite-magnetite-pyrite, and hematite-magnetite to buffer fO2, aH2(aq) and aH2S(aq) at geologically reasonable values.Results of the experiments suggest that under appropriate physical and chemical conditions, metastable redox dependent thermodynamic equilibrium involving liquid water and inorganic iron-bearing mineral assemblages may regulate the relative abundance of short chain alkanes and their corresponding alkenes. In addition, alkenes represent an important intermediary in the conversion of n-alkanes to methane and oxidized species such as carbon dioxide, ketones alcohols, and organic acids.The rates of redox dependent organic reactions during the experiments were strongly influenced by the presence of sulfur. Under relatively oxidizing conditions greater catalytic activity due to the presence of dissolved sulfur species was observed. Fluid speciation calculations suggest that oxidized aquous sulfur compounds represent the catalytically active species.These results suggest that redox conditions and the presence or absence of dissolved sulfur species in natural sedimentary environments may strongly influence the stability of hydrocarbons. Accordingly, models used to predict the stability of oil and the formations of natural gas need to account for chemical processes that involve both organic and inorganic sedimentary components.

Behaviour of RNA under hydrothermal conditions and the origins of life

2004 ◽  
Vol 3 (4) ◽  
pp. 301-309 ◽  
Author(s):  
Kunio Kawamura
Keyword(s):  
High Temperatures ◽  
Open Systems ◽  
Rna World ◽  
Enzymatic Reaction ◽  
Reaction Rates ◽  
Extensive Literature ◽  
Hydrothermal Conditions ◽  
Phosphodiester Bond ◽  
Rna Molecules ◽  
The Stability

The RNA world hypothesis and the hydrothermal origin of life hypothesis are contradictory to each other. Although it is considered that RNA molecules are too labile to maintain life-like systems at high temperatures and there is extensive literature on nucleic acid hydrolysis, the stability and the chemical evolution of RNA have not been sufficiently analysed from the viewpoint of hydrothermal reactions. Based on our experimental data concerning the stability and the prebiotic formation of RNA at high temperatures, two different aspects seem to be important for evaluating whether RNA molecules are too labile. First, the stability of RNA molecules should be evaluated from the comparison of the rate of formation and the rate of degradation of RNA in open systems. Our prebiotic reaction models of phosphodiester bond formation suggest that at high temperatures the accumulation of RNA may be possible. However, an RNA world entirely consisting of RNA molecules is unlikely to occur because the biologically important interactions are not effective for the bare RNA molecules at high temperatures. Second, since enzymes presently mediate most biological reactions, evaluation of the accumulation of RNA should be based on the comparison between the enzymatic and non-enzymatic reaction rates. Hence, the evaluation of the primitive enzymatic reaction rates at high temperatures has been attempted. There is a large difference between the present enzymatic reaction rates at 25–90 °C and the non-enzymatic reaction rates at high temperatures of 200–300 °C. It is thus possible that prebiotic enzyme-like assemblies could have facilitated the accumulation of RNA molecules at hydrothermal vent temperatures.

scholarly journals A Spiral of Distrust: A Panel Study on the Relation between Political Distrust and Protest Voting in Belgium

2016 ◽  
Vol 53 (1) ◽  
pp. 104-130 ◽  
Author(s):  
Marc Hooghe ◽  
Ruth Dassonneville
Keyword(s):  
Safety Valve ◽  
Panel Study ◽  
Political Trust ◽  
Panel Analysis ◽  
Political Distrust ◽  
Dynamic Perspective ◽  
Low Levels ◽  
The Stability ◽  
The Relationship ◽  
Observation Period

Low levels of political trust are associated with a preference for protest parties. Some authors have argued that in this manner protest parties indirectly contribute to the stability of electoral democracy, functioning as a ‘safety valve’ for political discontent. In this article, we investigate the relationship between protest voting and political trust in a dynamic perspective, relying on a five-year Belgian panel study. We confirm that citizens with low levels of political trust are more likely to vote for protest parties. Additionally, we point out that decreasing levels of trust significantly increase the probability of voting for a protest party, even controlling for absolute levels of trust. Most importantly, having voted for a protest party in 2009 is linked to a subsequent further drop in political trust during the 2009–14 observation period. The panel analysis suggests that distrust and protest voting reinforce one another, leading to a potential spiral of distrust.

scholarly journals Analisis Potensi Ekonomi Sektoral Kabupaten Humbang Hasundutan Tahun 2010-2018

2020 ◽  
Vol 1 (2) ◽  
pp. 59-75
Author(s):  
Elvis F. Purba
Keyword(s):  
Economic Growth ◽  
Growth Rate ◽  
Economic Potential ◽  
Location Quotient ◽  
Annual Average ◽  
Economic Growth Rate ◽  
Government Administration ◽  
Average Value ◽  
Over Time ◽  
Observation Period

This paper describes the economic potential of each industrial origin Humbang Hasundutan regency period 2010-2018. The analysis is based on: (1) location quotient (LQ), (2) sectoral contribution to GDRP, and (3) sectoral contribution to the regency's economic growth rate. Assuming that there is no a drastic change in the sectoral GDRP value in one or several industrial origin, the annual average value from the observation period is used. Furthermore, to determine the economic potential of each industrial origin based on established quantitative criteria. The results of data analysis indicate that only one industrial origin has high economic potential, namely agriculture, forestry and fisheries. Then there are two industrial origin with moderate potential, i.e.: (1) construction and (2) government administration, defense and campulsory social security. The remaining fourteen other industrial origin have low potential. Over time, it is estimated that there will be changes in the contribution of each industrial origin to GDRP and the rate of regency economic growth. However, agriculture, forestry and fisheries are estimated to still have high potential in the next few decades, especially since Humbang Hasundutan regency has been designated as one of the food estate for Indonesia.

scholarly journals Ecological-phytocenotic analysis of the field layer of urban recreational forests (on the example of Kaluga and Obninsk)

2020 ◽  
pp. 68-75
Author(s):  
A. A. Evseeva
Keyword(s):  
Forest Ecosystems ◽  
Urban Forests ◽  
Practical Significance ◽  
Anthropogenic Pressure ◽  
Forest Communities ◽  
Field Layer ◽  
The Stability ◽  
The City ◽  
Forest Habitats ◽  
Observation Period

The aim of this study is to study the diversity of the ecological-coenotic structure of the field layer of the residual urban forests, using as an example the cities Kaluga and Obninsk, which have different approaches to the conservation of residual forest communities in the city. Obninsk practices the conservation of forest zones that have entered the urban environment as recreational objects, while in Kaluga, such forest communities are in a state of interrupted succession and have experienced forestry activities. The objectives of the study are to study the ecological-coenotic and ecological-biological spectra of the field layer of forest ecosystems, and to identify adventive and protected plant species. The study took place in 2014–2015. In the forest communities under study, 30 sites were selected for geobotanical descriptions by the Braun-Blanquet method at different periods of the growing season (in June and August) to fully cover floristic diversity. A total during the observation period were made 240 floristic descriptions. Kaluga city forests turned out to be more susceptible to negative changes occurring in conditions of recreational for-est management. The field layer of the Kaluga forest recreational zones turned out to be more susceptible to negative changes occurring under the influence of anthropogenic pressure, in comparing with the Obninsk forest recreational zones. This is ex-pressed in the proportion of ecological-coenotic and ecological-biological groups, the presence of a greater number of alien species in the studied communities of Kaluga, which indicates greater resistance to the recreational load of the city forests of Obninsk. For example, the share of the group of forest habitats is much higher in Obninsk, where forest species make up more than half of all types of grass layer (54,2%). In the Kaluga forests, the share of forest habitats is lower and amounted to 47,5%. The discovered difference in the stability of the field layer of the Obninsk forests is presumably due to the strategy of their conservation in the urban area in a state of natural succession. The practical significance of the results obtained can be the possibility of using them to determine the degree of negative changes in recreational forests. The direction of further research can be directed at organizing monitoring of the urban forests of Kaluga and Obninsk according to the state of the field layer

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