Journal articles on the topic 'Positive slope'
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Peng, Yao, Jun Huang, Shao Bin Dai, and Ting Yuan. "Dynamic Analysis on the Light-Weight Portal Frame with Different Slopes." Applied Mechanics and Materials 405-408 (September 2013): 775–80. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.775.
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Build up a group of light-weight portal frame models with different slopes by SAP2000 software. Conduct dynamic time-history analysis on light-weight portal frame models with different slopes under the EI Centro wave. The results show that: The maximum positive and negative displacement and acceleration of the light-weight portal frame presents a variation rule as the the slope increasing; the influence of the slope on the maximum positive and negative displacement of the frame is relatively small, while it is big on the maximum positive and negative acceleration; the acceleration amplification coefficient of the frame decreases as the slope increasing when the slope exceeds a limit, which show that the earthquake damage of the large slope light-weight portal frame increases as the slope increasing.
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Grabowecky, Marcia, Stacey Parrott, Emmanuel Guzman-Martinez, Laura Ortega, and Satoru Suzuki. "Auditory–visual, positional, and semantic effects in visual extraction of slope." Seeing and Perceiving 25 (2012): 196. http://dx.doi.org/10.1163/187847612x648251.
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Extracting slopes from arrays of visual features is crucial for interpreting graphs. To understand broader influences on slope perception, we investigated the effects of concurrent sounds, of relative graph location, and of semantic priming on a visual search task in which observers searched for a graph with a positive or negative slope. Four bar graphs or scatter plots were simultaneously presented in separate quadrants of a visual display. Participants pressed a key as quickly as possible if one of the graphs displayed the target slope and otherwise refrained from response. A concurrently presented ascending pitch slowed responses to negative-slope targets, and concurrently presented descending pitch slowed responses to positive-slope targets, indicating crossmodal interference. This interference was eliminated when the sounds were presented 200 ms before the graphs, consistent with crossmodal interaction rather than response bias. Positive slopes were detected slowest in the upper-left quadrant whereas negative slopes were detected slowest in the upper-right quadrant, suggesting that slope detection is impeded when a graph is placed inconsistently with a mental number-line representation (negative values on the left and positive values on the right). Finally, positive slopes were detected faster when the search display was immediately preceded by a briefly flashed word ‘uphill’ compared to the word ‘downhill’ (and the converse for negative slopes), indicating a semantic priming effect, but this was observed only for scatter plots (the stimulus specificity precluding response bias). In summary, perception of visual slope is systematically influenced by auditory signals, by location of graphs, and by semantic priming.
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Zhao, Zi Chao, Wen Nian Xu, and Dong Xia. "Soil Nutrient and Soil Enzyme Activity of the Slopes with Different Ecological Protection Technologies." Advanced Materials Research 356-360 (October 2011): 2445–50. http://dx.doi.org/10.4028/www.scientific.net/amr.356-360.2445.
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Taking four types of slopes as test objects this paper measured their, soil nutrient and soil enzyme activity. The results showed that variation of soil nutrients in different slopes is obvious; soil enzyme activity is also a significant difference between different slopes. The soil of A slope (natural secondary forest ) was the highest in activity of urease, invertase, neutral phosphatase and catalase, the lowest in D(wasteland)slope except catalase. There were extremely significant positive correlations among soil urease activity, invertase activity and neutral phosphatase activity. Significant positive correlations were observed between soil urease activity, invertase activity, neutral phosphates activity and organic matter, available N, total N. It suggested that enzymatic activity could be used to indicate and estimate soil fertility of artificial remediation slopes. Combined with and community structure and community characteristics of vegetation on the sanmpled slops, soil enzyme activities could be used to measure the degree of vegetation restoration in the disturbed area.
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Debabeche, Mahmoud, Sonia Cherhabil, Amin Hafnaoui, and Bachir Achour. "Hydraulic jump in a sloped triangular channel." Canadian Journal of Civil Engineering 36, no. 4 (April 2009): 655–58. http://dx.doi.org/10.1139/l08-136.
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The hydraulic jump in a sloped triangular channel of 90° central angle is theoretically and experimentally examined. The study aims to determine the effect of the channel's slope on the sequent depth ratio of the jump. A theoretical relation is proposed for the inflow Froude number as function of the sequent depth ratio and the channel slope. An experimental analysis is also proposed to find a better formulation of the obtained relation. For this motive, six positive slopes are tested. The relations obtained are recommended for designing irrigation ditches.
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Deng, Xiaopeng, and Xinghua Xiang. "Fuzzy Comprehensive Evaluation Method for Evaluating Stability of Loess Slopes." Advances in Civil Engineering 2023 (November 23, 2023): 1–15. http://dx.doi.org/10.1155/2023/6692746.
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The stability assessment of loess slopes is of great significance for slope reinforcement and safety assessment. This research studies the main factors affecting the stability of the loess slope through the summary and analyzes the failure cases of the loess slope in Shaanxi Province. The importance of influencing factors was studied through numerical simulation method, sensitivity analysis method, and gray correlation analysis method, and the weight value method was given. On this basis, we have developed the fuzzy comprehensive evaluation model method for assessing the stability of loess slopes based on the principle of maximum membership degree. Finally, the method was applied to the stability analysis of the actual loess slope, and the rationality and correctness of the loess slope stability evaluation method proposed in this paper were demonstrated. The results showed that, for the Shaanxi loess slope, the probability of instability of the positive slopes is far greater than that of negative slopes; the greater the slope gradient, the more unstable the loess slopes. Collapse mainly occurs in the range of 10–40 m slope height. There is a significant positive correlation between rainfall and the probability of loess landslides. The degree of correlation between the factors influencing slope stability and the safety factor can be categorized from strong to weak as follows: slope inclination > internal friction angle > height of the slope > gravitational forces > cohesion > Poisson’s ratio > modulus of elasticity, and the influence of Poisson’s ratio and elastic modulus can be ignored. The fuzzy comprehensive evaluation method based on the gray correlation degree method established in this paper was used to evaluate the stability of the loess slopes. The evaluation results attested to the actual data of slope monitoring. The evaluation method proves reasonable and feasible and can be well applied to the stability analysis of the loess slopes.
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Naqellari, Alqi. "Positive Slope Model of Aggregate Demand." Academic Journal of Interdisciplinary Studies 7, no. 3 (November 1, 2018): 63–85. http://dx.doi.org/10.2478/ajis-2018-0059.
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Abstract This paper analyzes Internal Aggregate Demand. This aggregate, along with other production indicators, is the main indicator of the country’s economic performance rate. Objective analysis is important for their perspective, as well as for a set of other related indicators, such as inflation rate, unemployment rate, etc. In economic theory, the Aggregate Demand Curve (AD) deals with negative slope. At the point where AD interrupts the AS (aggregate supply curve) there is macroeconomic equilibrium. Creating this equilibrium, shifting curves, creates a number of other figures that show how the level of output, prices and employment will be, and overall the level of economy in the future. In this study, with the data of the Albanian economy, was built, for a period of 17 years, the Internal Demand Curve. Three effects are analyzed: the real balance sheet effect, the interest rates and the external trade effect. The internal demand curve has resulted in a Positive Slope. The equilibrium is not created at the intersection point of the curves. These curves stand facing each other. The equilibrium is set by the different aggregate price level. The Gross Domestic Product Curve (GDP) is the equilibrium curve created by the interaction of Aggregate Demand and Aggregate Supply. This position is real, and creates opportunities for objective analysis of the economy. This paper uses econometric, statistical, comparative and synthesis methods.
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Krisnanto, Sugeng, and Harianto Rahardjo. "Characteristics of Rainfall-Induced Slope Instability in Cisokan Region, Indonesia." Journal of Engineering and Technological Sciences 53, no. 5 (October 22, 2021): 210504. http://dx.doi.org/10.5614/j.eng.technol.sci.2021.53.5.4.
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A 25.5 km long access road has been constructed in a hilly area in Cisokan region. Several slope instabilities occurred during the rainy season, particularly at the end of heavy rainfall. A comprehensive study was performed to understand the characteristics of rainfall-induced slope instability. The study consisted of field observation, analyses of field and laboratory test data, and numerical analyses. The study revealed that in general there were two categories of slopes with instability characteristics: (i) slopes with a significant groundwater level increase during rainfall; (ii) slopes with an insignificant groundwater level increase during rainfall. In the first category, the slope instability was caused by a loss of matric suction and eventually the pore-water pressure, uw became positive as indicated by an increase of the groundwater level. In the second category, the slope instability was caused by a loss of matric suction without a rise in pore-water pressure, uw, to a positive magnitude. Two empirical curves of slope stability were developed as a preliminary guidance to assess slope stability during rainfall in the region.
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Lorinc, Z., J. Derr, M. Snider, and R. Lydic. "Defining origin of positive slope in hypercapnic ventilatory response curve." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 261, no. 3 (September 1, 1991): R747—R751. http://dx.doi.org/10.1152/ajpregu.1991.261.3.r747.
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The sensitivity to CO2 as a respiratory stimulant has traditionally been studied by exposing organisms to progressively increasing levels of inspired CO2 while measuring the corresponding increase in minute ventilation (V). Plots of V as a function of end-tidal CO2 concentration reveal a complex function with a "dogleg" shape. Only the positive slope of the V function is taken as an index of chemosensitivity, but the starting points for such analyses are often chosen arbitrarily. This paper examined the hypotheses that the range of CO2 concentrations over which V slopes are compared may be mathematically defined and that arbitrary choices of this analytic range may influence conclusions about the hypercapnic ventilatory response (HCVR). Three mathematical models attempted to define the origin of the positive slope for the HCVR curve using empirically derived data. The results revealed good agreement that the origin of the positive HCVR slope may be reliably defined by a point that joins the horizontal and positive slope of the HCVR curve. In addition to identifying the "joint-point" statistic, the results suggest that arbitrarily defining the range of CO2 values over which V is analyzed can be replaced by quantitative approaches for identifying the origin of the ventilatory response to hypercapnia.
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Javankhoshdel, Sina, and Richard J. Bathurst. "Influence of cross correlation between soil parameters on probability of failure of simple cohesive and c-ϕ slopes." Canadian Geotechnical Journal 53, no. 5 (May 2016): 839–53. http://dx.doi.org/10.1139/cgj-2015-0109.
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This paper focuses on the calculation of probability of failure of simple unreinforced slopes and the influence of the magnitude of cross correlation between soil parameters on numerical outcomes. A general closed-form solution for cohesive slopes with cross correlation between cohesion and unit weight was investigated and results compared with cases without cross correlation. Negative cross correlations between cohesion and friction angle and positive cross correlations between cohesion and unit weight, and friction angle and unit weight were considered in the current study. The factors of safety and probabilities of failure for the slopes with uncorrelated soil properties were obtained using probabilistic slope stability design charts previously reported by the writers. Results for cohesive soil slopes and positive cross correlation between cohesion and unit weight are shown to decrease probability of failure. Probability of failure also decreased for increasing negative cross correlation between cohesion and friction angle, and increasing positive correlation between cohesion and unit weight, and friction angle and unit weight. Probabilistic slope stability design charts presented by the writers in an earlier publication are extended to include cohesive-frictional (c-[Formula: see text]) soil slopes with and without cross correlation between soil input parameters. An important outcome of the work presented here is that cross correlation between random values of soil properties can reduce the probability of failure for simple slope cases. Hence, previous probabilistic design charts by the writers for simple soil slopes with uncorrelated soil properties are conservative (safe) for design. This study also provides one explanation why slope stability analyses using uncorrelated soil properties can predict unreasonably high probabilities of failure when conventional estimates of factor of safety suggest a stable slope.
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Yin, Xiangjie, Hang Lin, Yifan Chen, Yixian Wang, and Yanlin Zhao. "Precise evaluation method for the stability analysis of multi-scale slopes." SIMULATION 96, no. 10 (August 3, 2020): 841–48. http://dx.doi.org/10.1177/0037549720943274.
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Slope stability analysis is a multi-scale problem. Typically, owing to the distinctions of slope scales (e.g., slope height or slope angle) in practical engineering, the stability calculation results of slopes with various scales from numerical methods inevitably exhibit different computational precision levels in the case of identical computational grids, and therefore the stability results of different slopes cannot be compared. To achieve equal accuracy stability analysis for multi-scale slopes, this study establishes numerical models of slopes with various scales as well as different grid shapes and sizes to conduct stability analysis. The results show the following: (a) a positive correlation relationship exists between the safety factor of the slope and the scaling factor, which is defined as the ratio of the grid size to the slope height; (b) the definition of the refined safety factor is given, representing the safety factor that corresponds to the infinitesimal grid size and eliminating the computational error of slope stability analysis caused by grid size or shape; (c) on this basis, embarking on the composite influence of multiple scales of slope on stability analysis, the study proposes a simplified treatment method suitable for evaluating the refined safety factor of the multi-scale slopes, which is verified as valid and feasible by some examples.
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Dewolf, A. H., Y. P. Ivanenko, K. E. Zelik, F. Lacquaniti, and P. A. Willems. "Differential activation of lumbar and sacral motor pools during walking at different speeds and slopes." Journal of Neurophysiology 122, no. 2 (August 1, 2019): 872–87. http://dx.doi.org/10.1152/jn.00167.2019.
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Organization of spinal motor output has become of interest for investigating differential activation of lumbar and sacral motor pools during locomotor tasks. Motor pools are associated with functional grouping of motoneurons of the lower limb muscles. Here we examined how the spatiotemporal organization of lumbar and sacral motor pool activity during walking is orchestrated with slope of terrain and speed of progression. Ten subjects walked on an instrumented treadmill at different slopes and imposed speeds. Kinetics, kinematics, and electromyography of 16 lower limb muscles were recorded. The spinal locomotor output was assessed by decomposing the coordinated muscle activation profiles into a small set of common factors and by mapping them onto the rostrocaudal location of the motoneuron pools. Our results show that lumbar and sacral motor pool activity depend on slope and speed. Compared with level walking, sacral motor pools decrease their activity at negative slopes and increase at positive slopes, whereas lumbar motor pools increase their engagement when both positive and negative slope increase. These findings are consistent with a differential involvement of the lumbar and the sacral motor pools in relation to changes in positive and negative center of body mass mechanical power production due to slope and speed. NEW & NOTEWORTHY In this study, the spatiotemporal maps of motoneuron activity in the spinal cord were assessed during walking at different slopes and speeds. We found differential involvement of lumbar and sacral motor pools in relation to changes in positive and negative center of body mass power production due to slope and speed. The results are consistent with recent findings about the specialization of neuronal networks located at different segments of the spinal cord for performing specific locomotor tasks.
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Zhang, Zhiming, Sai Wu, Huimin Miao, and Tong Zhang. "Numerical Investigation of Flow Channel Design and Tapered Slope Effects on PEM Fuel Cell Performance." Sustainability 14, no. 18 (September 6, 2022): 11167. http://dx.doi.org/10.3390/su141811167.
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High-power proton exchange membrane (PEM) fuel cell vehicles are important for the realization of carbon neutrality in transportation. However, it is difficult to maintain enough fuel supply and quick water removal capacity at a high current density where reactant gas transportation and water concentration are directly affected by flow channel configurations. This study aims to investigate the tapered slope effects of a flow channel on fuel cell performance using a 3-D CFD model. The positive, negative, zero and hybrid tapered slopes are proposed to illustrate the fuel cell voltage, reactant gas and water vapor concentration in the flow channels. Among them, the flow channel with a positive tapered slope performs better, especially at a high current density. Then, the positive tapered slope effects are discussed, including different tapered slopes, inlet depths and widths of flow channels. The results show that the larger the tapered slope, the smaller the depth and width, and the better the fuel cell performs; the corresponding current densities are increased by a maximum of 6.53%, 12.72% and 61.13%. The outcomes stated above provide a key direction for flow channel design that can particularly achieve higher fuel cell power density at high current densities.
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Wang, Lei, Yan Li, Jiajun Wu, Zhizhuang An, Linna Suo, Jianli Ding, Shuo Li, Dan Wei, and Liang Jin. "Effects of the Rainfall Intensity and Slope Gradient on Soil Erosion and Nitrogen Loss on the Sloping Fields of Miyun Reservoir." Plants 12, no. 3 (January 17, 2023): 423. http://dx.doi.org/10.3390/plants12030423.
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Environmental loss is primarily caused by soil, water, and nutrient loss, and runoff is associated with nutrient transport and sediment loss. Most existing studies have focused on one influencing factor, namely slope gradient or rainfall intensity, for slope erosion and nutrient loss, but the joint effects of the two factors have rarely been researched. In this context, the impact of slope gradients (0°, 5°, 10°, and 15°) and rainfall intensities (30, 40, 50, 60, 70, and 80 mm/h) on soil erosion and nutrient loss on the sloping fields of Miyun Reservoir were explored using the indoor artificial rainfall simulation testing system. Based on the results of the study, the variation of runoff coefficient with slope gradient was not noticeable for rainfall intensities <40 mm/h; however, for rainfall intensities >40 mm/h, the increased range of runoff coefficient doubled, and the increase was the fastest under 0° among the four slope gradients. The slope surface runoff depth and runoff rate showed positive correlations with the rainfall intensity (r = 0.875, p < 0.01) and a negative correlation with the slope gradient. In addition, the cumulative sediment yield was positively related to the slope gradient and rainfall intensity (r > 0.464, p < 0.05). Moreover, the slope surface runoff-associated and sediment-associated loss rates of total nitrogen (TN) rose as the rainfall intensity or slope gradient increased, and significant linear positive correlations were found between the runoff-associated TN loss rate (NLr) and the runoff intensity and between the sediment-associated NLr and the erosion intensity. In addition, there were positive linear correlations between slope runoff-associated or sediment-associated TN loss volumes and rainfall intensity, surface runoff, and sediment loss volumes, which were highly remarkable. The slope gradient had a significant positive correlation with the slope surface runoff-associated TN loss at 0.05 (r = 0.452) and a significant positive correlation with the sediment-associated TN loss at the level of 0.01 (r = 0.591). The rainfall intensity exhibited extremely positive correlations with the slope surface runoff-associated and sediment-associated TN loss at 0.01 (r = 0.717 and 0.629) Slope gradients have less effect on nitrogen loss on sloped fields than rainfall intensity, mainly because rainfall intensity affects runoff depth. Based on the findings of this study, Miyun Reservoir may be able to improve nitrogen loss prevention and control.
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Wang, Yueying, Songtao Wang, Bing Jiang, Yihao Zhu, Xuchang Niu, Changjiang Li, Zhen Wu, and Weifeng Chen. "Regulation of Abiotic Factors on Aboveground Biomass and Biodiversity of Ditch Slope in Coastal Farmland." Water 14, no. 21 (November 4, 2022): 3547. http://dx.doi.org/10.3390/w14213547.
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Ditch plant biomass and diversity play an important role in maintaining ditch ecosystem structure and function stability, which are subject to environmental changes. However, the regulation of abiotic factors on the aboveground biomass and diversity of plants on the slopes of coastal agricultural ditches remains unclear. In this study, the spatial distribution of soil physicochemical properties, aboveground biomass, and diversity of vegetation on different slope positions (upper slope, middle slope, and lower slope) and slope aspects (north-south direction) of farmland drainage ditches and their correlations were investigated through field surveys of vegetation on the slopes of coastal farmland drainage ditches at different sampling sites. First, water content and bulk density) decreased with the increase of slope position, while the salinity showed the opposite spatial distribution characteristics and the distribution of soil nutrients in space was mainly concentrated in the 0–20 cm soil layer. Second, the aboveground biomass of vegetation was significantly higher on the south slope than on the north slope, with the highest biomass at the lower slope on the south slope and higher aboveground biomass on the north slope at the upper and middle slopes. The Shannon-Wiener index, Pielou index, and Margalef index of ditch slope vegetation in Dongying and Binzhou farmland ditch slopes showed the same pattern of change at different slope positions and directions, which were significantly higher at the upper and middle slopes than at the lower slopes. In contrast, the Simpson index showed the opposite pattern, decreasing with the increase in slope position. Further, WC, BD, organic matter content, and total nitrogen content had positive effects on vegetation aboveground biomass, while soil pH, salinity, and available potassium content hindered vegetation growth. Finally, the Shannon-Wiener index and Pielou index were positively correlated with soil BD and available phosphorus content, and negatively correlated with organic matter and total nitrogen content, while the Simpson index was positively correlated with soil BD and WC, and had a significant negative correlation with soil salinity.
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Ai, Ze Min, Jiao Yang Zhang, Hong Fei Liu, Sha Xue, and Guo Bin Liu. "Influence of slope aspect on the microbial properties of rhizospheric and non-rhizospheric soils on the Loess Plateau, China." Solid Earth 9, no. 5 (October 9, 2018): 1157–68. http://dx.doi.org/10.5194/se-9-1157-2018.
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Abstract. Slope aspect is an important topographic factor in the micro-ecosystem environment, but its effect on the microbial properties of grassland rhizospheric soil (RS) and non-rhizospheric soil (NRS) remain unclear. A field experiment was conducted at the Ansai Research Station on the Loess Plateau in China to test the influence of slope aspects (south-facing, north-facing, and northwest-facing slopes, all with Artemisia sacrorum as the dominant species) on RS and NRS microbial biomass carbon (MBC) contents, phospholipid fatty acid (PLFA) contents, and the rhizospheric effect (RE) of various microbial indices. Soil samples were collected from the three slope aspects, including rhizospheric and non-rhizospheric region, and analyzed to determine the various related microbial indices. The results showed that MBC content differed significantly among the slope aspects in RS but not in NRS, and the RE for MBC content in the south-facing slope was larger than that in the north-facing slope. RS total, bacterial, and Gram-positive bacterial PLFA contents in the south-facing slope were significantly lower than those in the north- and northwest-facing slopes, and RS Gram-negative bacterial (G−) and actinomycete PLFA contents in the south-facing slope were significantly lower than those in the north-facing slope. In contrast, NRS total, bacterial, and G− PLFA contents in the north-facing slope were significantly higher than those in the south- and northwest-facing slopes, and NRS fungal and actinomycete PLFA contents in the north- and south-facing slopes were significantly higher than those in the northwest-facing slope. RE for all PLFA contents except fungal in the northwest-facing slope were higher than those in the south-facing slope. Slope aspect significantly but differentially affected the microbial properties in RS and NRS, and the variable influence was due to an evident RE for most microbial properties.
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KALLE, CHARLENE. "Isomorphisms between positive and negative -transformations." Ergodic Theory and Dynamical Systems 34, no. 1 (November 9, 2012): 153–70. http://dx.doi.org/10.1017/etds.2012.127.
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AbstractWe compare a piecewise linear map with constant slope $\beta \gt 1$ and a piecewise linear map with constant slope $-\beta $. These maps are called the positive and negative $\beta $-transformations. We show that for a certain set of $\beta $s, the multinacci numbers, there exists a measurable isomorphism between these two maps. We further show that for all other values of $\beta $between 1 and 2 the two maps cannot be isomorphic.
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Propp, Douglas A. "Caveat emptor: The positive D-Dimer Slippery Slope." Annals of Emergency Medicine 42, no. 2 (August 2003): 309–10. http://dx.doi.org/10.1067/mem.2003.314.
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Kato, M., N. Yoshizawa, T. Sugie, and K. Okamoto. "Dispersion slope equaliser using bend-induced positive dispersion slope in coiled pure-silica fibre." Electronics Letters 37, no. 11 (2001): 680. http://dx.doi.org/10.1049/el:20010481.
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Ding, Hao, Lei Xue, Hongyan Liu, Longfei Li, Haoyu Wang, and Mengyang Zhai. "Influence of Root Volume, Plant Spacing, and Planting Pattern of Tap-like Tree Root System on Slope Protection Effect." Forests 13, no. 11 (November 16, 2022): 1925. http://dx.doi.org/10.3390/f13111925.
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Vegetation slope protection has been widely utilized as an eco-friendly approach for slope stability. Up to now, research on the slope protection effect of shrubs and herbaceous vegetation is more than those of trees, which can be attributed to the challenge of evaluating the slope protection effect of tree root systems that can be influenced by many factors, such as root morphology, root volume, plant spacing, and planting patterns. Therefore, this study takes tap-like tree root systems as the research object, constructs the corresponding root-soil composite model by using 3D printing technology, and carries out a series of physical model experiments on slopes supported by tap-like tree root systems, examining the anti-sliding force, slope surface displacement, sliding range, and slope cracks throughout the entire process of deformation and the damage to shallow slopes, to finally evaluate the effectiveness in the slope protection effect of tree root systems from multiple perspectives. The results indicate that: (1) the peak anti-sliding force of the slope supported by tree root systems correlates positively with the root volume and negatively with plant spacing generally, and the influence of tree plant spacing on the peak anti-sliding force is weaker than that of the root volume; (2) the displacement of slopes supported by tree root systems in the square planting pattern is generally less than that in the staggered planting pattern, and the displacement of slopes has a negative correlation with the root volume and a positive correlation with the plant spacing; (3) the sliding range of the slope supported by tree root systems is significantly reduced compared with that of the unsupported slope, and the tree root system can prevent the occurrence of slope surface cracks to a certain extent, which makes the sliding-body show better integrity. The above understanding enriches the study on the slope protection effect of the tree root system, reveals the influence of the tree root volume, plant spacing, and planting pattern (square distribution and staggered distribution) of the tap-like tree root system, and offers some guidance for the engineering application of tree slope protection in practice.
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Sabin, M. J. "DPCM coding of spectral amplitudes without positive slope overload." IEEE Transactions on Signal Processing 39, no. 3 (March 1991): 756–58. http://dx.doi.org/10.1109/78.80867.
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Montgomery, Jana R., and Alena M. Grabowski. "The contributions of ankle, knee and hip joint work to individual leg work change during uphill and downhill walking over a range of speeds." Royal Society Open Science 5, no. 8 (August 2018): 180550. http://dx.doi.org/10.1098/rsos.180550.
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The muscles surrounding the ankle, knee and hip joints provide 42, 16 and 42%, respectively, of the total leg positive power required to walk on level ground at various speeds. However, each joint's contribution to leg work when walking up/downhill at a range of speeds is not known. Determining each biological joint's contribution to leg work over a range of speeds and slopes can inform the design of biomimetic assistive devices (i.e. prostheses). Twenty healthy adults walked 1.00, 1.25 and 1.50 m s −1 on 0°, ±3°, ±6° and ±9° while we collected kinematic and kinetic data. We calculated sagittal plane joint work and individual leg work over the entire stance phase. The ratio of ankle joint to total individual leg positive work (summed ankle, knee and hip joint work) did not change (0.42) with speed or slope, but the ratio of ankle joint to individual leg negative work was 0.38 at −9°, 0.42 at 0° and 0.27 at +9° across all speeds. The ratio of ankle joint to total individual leg negative work was 0.41 at 1.00 m s −1 and 0.32 at 1.50 m s −1 across all slopes. The ratio of knee joint to total individual positive leg work (0.22) did not change with speed or slope. The ratio of knee joint to total individual leg negative work was 0.39 at 1.00 m s −1 and 0.45 at 1.50 m s −1 across all slopes. The ratio of hip joint to total individual leg positive work did not change with speed but was 0.34 at −9°, 0.33 at 0° and 0.37 at +9° across all speeds. The ratio of hip joint to total individual leg negative work was 0.21 at 1.00 m s −1 , and 0.24 at 1.50 m s −1 across all slopes and 0.17 at −9°, 0.19 at 0° and 0.29 at +9° across all speeds. The ankle significantly contributes to walking on slopes and this contribution changes during sloped compared with level-ground walking, thus assistive devices that provide biomimetic ankle function must adapt to accommodate walking at different speeds and slopes; whereas assistive biomimetic devices for the knee only need to adapt at different speeds.
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Wang, Bingyu, and Shijie Wang. "Shear Strength Analysis and Slope Stability Study of Straight Root Herbaceous Root Soil Composite." Applied Sciences 13, no. 23 (November 23, 2023): 12632. http://dx.doi.org/10.3390/app132312632.
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The instability of bare slopes is a prevalent concern. The root system of herbaceous vegetation enhances the shear strength of shallow slope soil. This study investigated the mechanism of the root-soil system as well as the effects of different influencing factors on the shear strength of the soil and slope stability. In particular, indoor experiments were conducted on rootless undisturbed soil (RUS) and undisturbed soil with a root system (USRS) using a triaxial compression apparatus to analyze the slope stability of composite soil with a Tagetes erecta root system. Significance tests and correlation analysis of the factors affecting shear performance were conducted. The slope reinforcement effect by the plant root system was simulated under 24 working conditions using the MIDAS finite element method. The results revealed the influence of the root content, moisture content, and stress on the shear strength of USRS, as well as the contribution degree and influence of these variables on the slope stability. Both RUS and USRS exhibited strain hardening during shearing. A strong negative (positive) correlation was observed between the internal friction angle (φ) (cohesion (c)) of the USRS and the root content (moisture content). The maximum deviatoric stress during shear failure of the USRS was 1.29 times higher than that of the RUS. Moreover, the root content was positively correlated with the slope safety coefficient and the slope of the line under different working conditions, whereas the slope angle was negatively correlated with the slope safety coefficient. The reinforcement effect by the root system resulted in a 11.2% increase in the safety coefficient and the improved stability of slopes with an angle larger than 1.5%. The findings of this study provide new insights into shallow slope stability in practical slope protection projects.
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Sun, Dayuan, Junzhuo Li, and Yuanbo Gong. "Effects of Planting Density of Poaceae Species on Slope Community Characteristics and Artificial Soil Nutrients in High-Altitude Areas." Sustainability 15, no. 10 (May 19, 2023): 8321. http://dx.doi.org/10.3390/su15108321.
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Ecological restoration of slopes in high-altitude areas is usually difficult. Gramineae species are widely used in slope vegetation restoration due to their strong adaptability and rapid growth. In the process of ecological slope protection, increasing the seeding rate of gramineous species usually improves the success rate of slope vegetation restoration, but the long-term effect is not obvious. Therefore, choosing an appropriate planting density of grass species is beneficial to the sustainable restoration of slopes in high-altitude areas. This study evaluated the effects of different planting densities of Poaceae species on community characteristics and artificial soil nutrients on high-altitude slopes. The slope ecological protection engineering experiment was carried out in Jiuzhaigou County, Sichuan Province. Commercial seed mixtures of five grasses and legumes were sown at three different planting densities of Poaceae species (10, 5, and 1 g/m2). Plant community species composition, community diversity index, and soil-available nutrients were determined annually. The results showed that there were differences in the species composition of the slope plant community under different planting densities. There was a significant negative logarithmic correlation between the community diversity indices and the planting density of grass species, and it changed with the recovery time. There were significant differences in hydrolyzed nitrogen, available phosphorus and available potassium in artificial soil, and they decreased with a logarithmic function of the recovery time. There was a positive correlation between the community diversity indices and the soil nutrient content. Overall, our study shows that low planting densities of Poaceae species are beneficial to the long-term stability of ecological restoration when ecological slope protection works are performed on slopes in high-altitude areas.
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Olfert, I. Mark, and G. Kim Prisk. "Effect of 60° head-down tilt on peripheral gas mixing in the human lung." Journal of Applied Physiology 97, no. 3 (September 2004): 827–34. http://dx.doi.org/10.1152/japplphysiol.01379.2003.
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The phase III slope of sulfur hexafluoride (SF6) in a single-breath washout (SBW) is greater than that of helium (He) under normal gravity (i.e., 1G), thus resulting in a positive SF6-He slope difference. In microgravity (μG), SF6-He slope difference is smaller because of a greater fall in the phase III slope of SF6 than He. We sought to determine whether increasing thoracic fluid volume using 60° head-down tilt (HDT) in 1G would produce a similar effect to μG on phase III slopes of SF6 and He. Single-breath vital capacity (SBW) and multiple-breath washout (MBW) tests were performed before, during, and 60 min after 1 h of HDT. Compared with baseline (SF6 1.050 ± 0.182%/l, He 0.670 ± 0.172%/l), the SBW phase III slopes for both SF6 and He tended to decrease during HDT, reaching nadir at 30 min (SF6 0.609 ± 0.211%/l, He 0.248 ± 0.138%/l; P = 0.08 and P = 0.06, respectively). In contrast to μG, the magnitude of the phase III slope decrease was similar for both SF6 and He; therefore, no change in SF6-He slope difference was observed. MBW analysis revealed a decrease in normalized phase III slopes at all time points during HDT, for both SF6 ( P < 0.01) and He ( P < 0.01). This decrease was due to changes in the acinar, and not the conductive, component of the normalized phase III slope. These findings support the notion that changes in thoracic fluid volume alter ventilation distribution in the lung periphery but also demonstrate that the effect during HDT does not wholly mimic that observed in μG.
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Selvaraj, Raja J., Peter Picton, Kumaraswamy Nanthakumar, and Vijay S. Chauhan. "Steeper restitution slopes across right ventricular endocardium in patients with cardiomyopathy at high risk of ventricular arrhythmias." American Journal of Physiology-Heart and Circulatory Physiology 292, no. 3 (March 2007): H1262—H1268. http://dx.doi.org/10.1152/ajpheart.00913.2006.
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Steep action potential duration (APD) restitution slopes (>1) and spatial APD restitution heterogeneity provide the substrate for ventricular fibrillation in computational models and experimental studies. Their relationship to ventricular arrhythmia vulnerability in human cardiomyopathy has not been defined. Patients with cardiomyopathy [left ventricular (LV) ejection fraction <40%] and no history of ventricular arrhythmias underwent risk stratification with programmed electrical stimulation or T wave alternans (TWA). Low-risk patients ( n = 10) had no inducible ventricular tachycardia (VT) or negative TWA, while high-risk patients ( n = 8) had inducible VT or positive TWA. Activation recovery interval (ARI) restitution slopes were measured simultaneously from 10 right ventricular (RV) endocardial sites during an S1-S2 pacing protocol. ARI restitution slope heterogeneity was defined as the coefficient of variation of slopes. Mean ARI restitution slope was significantly steeper in the high-risk group compared with the low-risk group [1.16 (SD 0.31) vs. 0.59 (SD 0.19), P = 0.0002]. The proportion of endocardial recording sites with a slope >1 was significantly larger in the high-risk patients [47% (SD 35) vs. 13% (SD 21), P = 0.022]. Spatial heterogeneity of ARI restitution slopes was similar between the two groups [29% (SD 16) vs. 39% (SD 34), P = 0.48]. There was an inverse linear relationship between the ARI restitution slope and the minimum diastolic interval ( P < 0.001). In cardiomyopathic patients at high risk of ventricular arrhythmias, ARI restitution slopes along the RV endocardium are steeper, but restitution slope heterogeneity is similar compared with those at low risk. Steeper ARI restitution slopes may increase the propensity for ventricular arrhythmias in patients with impaired left ventricular function.
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Peng, Bin, Yi Min Shang, Rui Shan Tan, and Tao Mei. "Research on Bearing Characteristics of the Digging Foundation in Slopes Based on Interface." Applied Mechanics and Materials 423-426 (September 2013): 2040–44. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.2040.
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The numerical simulation model was established by using numerical simulation tools of FLAC3D, through establishing interface for digging foundation-soil, which can consider mutual effect of digging foundation-soil. Bearing capacities of the digging foundation in slopes is calculated. The affecting factors of the bearing capacity are analyzed. The results show that the bearing capacity has a positive correlation with the distance between the foundation and the slope and has a negative correlation with the slope ratio, which can be expressed as a quadratic polynomial. Nonlinear regression analysis of calculation data are carried out and the fitting formula of the capacity ratio between pile in the slope and pile in the flat is obtained. Finally, the calculation method of horizontal bearing capacity about pile in the slope is developed, which can provide a reference to specification revision and engineering.
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Yao, Wenmin, Chong Ma, Zhang Wang, and Xiaolong Chen. "Stability analysis of strain-softening slopes based on the gravity increase method." HKIE Transactions 26, no. 1 (May 10, 2019): 30–38. http://dx.doi.org/10.33430/v26n1thie-2017-0031.
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With traditional slope stability analysis methods, it is difficult to accurately describe the progressive failure process and dynamic variation law of slope stability. The strain-softening constitutive model was therefore used to simulate the progressive failure process of a strain-softening slope based on the gravity increase method (GIM), with the displacement interface employed to determine the sliding surface. A sensitive analysis of the characteristic parameters within the softening stage was then conducted. The results are as follows: There are similar space-time evolution laws of residual strength factor and shear strain increment, with failure starting from the slope toe and extending gradually. The sliding surface of strain-softening slopes is located between that of the slope with peak strength and the sliding surface of the slope with residual strength. The stability coefficient shows an exponential growth trend with the increase of residual cohesion and residual plastic shear strain threshold, with a positive linear correlation between the residual friction angle and stability factor. The residual friction angle is the most sensitive factor in slope stability, followed by the residualcohesion, with the residual plastic shear strain threshold being the least sensitive.
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Stijak, Lazar, Zoran Blagojevic, Marko Kadija, Gordana Stankovic, Vuk Djulejic, Darko Milovanovic, and Branislav Filipovic. "The role-share-influence of the posterior tibial slope on rupture of the anterior cruciate ligament." Vojnosanitetski pregled 69, no. 10 (2012): 864–68. http://dx.doi.org/10.2298/vsp101230022s.
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Background/Aim. Posterior tibial slope is one of the most citated factors wich cause rupture of the anterior cruciate ligament (ACL). The aim of this study was to determine the association of a greather posterior tibial slope on the lateral condyle, that is a lesser posterior tibial slope on the medial condyle, with ACL rupture. Methods. The patients were divided into two groups. The study group included the patients with chronic instability of the knee besause of a previous rupture of ACL. The control group included the patients with knee lesion, but without ACL rupture. Posterior tibial slope measuring was performed by sagittal MR slices supported by lateral radiograph of the knee. We measured posterior tibial slope on lateral and medial condyles of the tibia. Using these values we calculated an average posterior tibial slope as well as the difference between slopes on lateral and medial condyles. Results. Patients with ACL rupture have highly statistically significantly greather posterior tibial slope (p < 0.01) on lateral tibial condyle (7.1? : 4.5?) as well as statistically significantly lesser posterior tibial slope (p < 0.05) on medial tibial condyle (5.0? : 6.6?) than patients with intact ACL. Conclusion. Great posterior tibial slope on lateral tibial condyle associated with the small posterior tibial slope on the medial tibial condyle, that is a positive differentce between lateral and medial tibial condyles are factors wich may cause ACL rupture.
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Bardhi, Diana. "Slopes Analyses - Case Study, Slope Stability of Bypass Project." European Journal of Engineering and Formal Sciences 4, no. 2 (October 15, 2021): 34. http://dx.doi.org/10.26417/466qfl71z.
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The scope of this study was to compare various stability evaluation methods. Accordingly, most common LE approaches were compared with the advanced LE (M‐P) method. Similarly, the differences in FOS computed from LE and FE analyses were compared based on a simple slope considering various load cases. In addition, two real slopes in a case study were analysed for the recorded minimum‐maximum GWT, pseudo‐static and dynamic conditions. Moreover, the stability evaluations of these slopes were based on both LE (M‐P) and FE (PLAXIS) calculation approaches, which both utilized shear strength parameters from advanced triaxle tests. Similarly, Mohr‐Coulomb model was applied in both approaches. The following conclusions are hence derived based on the reported work on both idealized and real slopes. To fulfil one of the aims of the study, the LE based methods are compared based on the factor of safety (FOS) obtained for various load combinations. The comparison is mainly based on simplified slope geometry and assumed input parameters. Among the LE methods, the Bishop simplified (BS), Janbu simplified (JS) and Janbu GPS methods are compared with the Morgenstern‐Price method (M‐PM). These LE methods are well established for many years, and thus some of them are still commonly used in practice for stability analysis. Moreover, the M‐PM has been compared with results from the FE analyses. Compared with theFE (PLAXIS) analyses, the LE (M‐PM) analyses may estimate 5 – 14percent higher FOS, depending on the conditions of a dry slope and a fully saturated slope with hydrostatic pore pressure distributions. For fully saturated conditions in the slope, inaccurate computation of stresses in LE methods may have resulted in larger difference in the computed FOS. Since, the FE software is based on stress‐strain relationship, stress redistributions are surely better computed even for a complicated problem. This has been found one of the advantages in FE simulations. A parameter study shows that the application of a positive dilatancy angle in FE analysis can significantly improve the FOS (4 ‐ 10percent). On contrast, the shear surface optimization in LE (M‐PM in SLOPE/W) analysis results in lower FOS, and thus minimizing the difference in FOS compared with FE analysis
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Picard, Ghislain, Marie Dumont, Maxim Lamare, François Tuzet, Fanny Larue, Roberta Pirazzini, and Laurent Arnaud. "Spectral albedo measurements over snow-covered slopes: theory and slope effect corrections." Cryosphere 14, no. 5 (May 7, 2020): 1497–517. http://dx.doi.org/10.5194/tc-14-1497-2020.
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Abstract. Surface albedo is an essential variable to determine the Earth's surface energy budget, in particular for snow-covered areas where it is involved in one of the most powerful positive feedback loops of the climate system. In situ measurements of broadband and spectral albedo are therefore common. However they are subject to several artefacts. Here we investigate the sensitivity of spectral albedo measurements to surface slope, and we propose simple correction algorithms to retrieve the intrinsic albedo of a slope from measurements, as if it were flat. For this, we first derive the analytical equations relating albedo measured on a slope to intrinsic direct and diffuse albedo, the apportionment between diffuse and direct incoming radiation, and slope inclination and aspect. The theory accounts for two main slope effects. First, the slope affects the proportion of solar radiation intercepted by the surface relative to that intercepted by the upward-looking, horizontal, sensor. Second, the upward- and downward-looking sensors receive reduced radiation from the sky and the surface respectively and increased radiation from neighbouring terrain. Using this theory, we show that (i) slope has a significant effect on albedo (over 0.01) from as little as a ≈1∘ inclination, causing distortions of the albedo spectral shape; (ii) the first-order slope effect is sufficient to fully explain measured albedo up to ≈15∘, which we designate “small-slope approximation”; and (iii) for larger slopes, the theory depends on the neighbouring slope geometry and land cover, leading to much more complex equations. Next, we derive four correction methods from the small-slope approximation, to be used depending on whether (1) the slope inclination and orientation are known or not, (2) the snow surface is free of impurities or dirty, and (3) a single or a time series of albedo measurements is available. The methods applied to observations taken in the Alps on terrain with up to nearly 20∘ slopes prove the ability to recover intrinsic albedo with a typical accuracy of 0.03 or better. From this study, we derive two main recommendations for future field campaigns: first, sloping terrain requires more attention because it reduces the measurement accuracy of albedo even for almost invisible slopes (1–2∘). Second, while the correction of the slope effect is possible, it requires additional information such as the spectral diffuse and direction partitioning and if possible the actual slope inclination and aspect, especially when the absence of impurities can not be assumed.
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Nguyen, Thanh Son, Trong-Toan Phan, Cong-Son Ha, and Ba-Danh Le. "Study on failure mechanisms of rainfall-induced landslides using physical model experiment and numerical analysis." Journal of Science and Technology in Civil Engineering (JSTCE) - HUCE 18, no. 2 (June 25, 2024): 12–27. http://dx.doi.org/10.31814/stce.huce2024-18(2)-02.
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Landslides are one of the most prevalent geological disasters in nature and rainfall infiltration is one of the key triggering factors of landslides. In this study, a laboratory flume model experiment was performed to investigate rainfall infiltration processes and failure mechanisms of sand slopes under artificial rainfall of 90 mm/h. Thenumerical simulation was then performed to compare the hydraulic responses and failure mechanism of the slope observed in the experiment. The results of the physical slope model demonstrated that water impoundingand a sudden increase in water level at the slope foot causes the local failure near the slope toe, followed by the development of cracking and retrogressive sliding extending up to the slope’s crest. The simulated results of the phreatic level are in good agreement with the experimental results, indicating the numerical proposed is capable of quantitatively well the hydraulic responses of slope upon rainfall. Both physical and numerical model results highlighted a positive correlation between slope failure and the development of the phreatic level within the slope. The results of this study would provide insights into the slope failure process and provide a dependable methodology for devising solutions to reduce the risk of landslides induced by rainfall infiltration.
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Jia, Hailing, Xiaoyan Ma, Johannes Quaas, Yan Yin, and Tom Qiu. "Is positive correlation between cloud droplet effective radius and aerosol optical depth over land due to retrieval artifacts or real physical processes?" Atmospheric Chemistry and Physics 19, no. 13 (July 12, 2019): 8879–96. http://dx.doi.org/10.5194/acp-19-8879-2019.
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Abstract. The Moderate Resolution Imaging Spectroradiometer (MODIS) C6 L3, Clouds and the Earth's Radiant Energy System (CERES) Edition-4 L3 products, and the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis data are employed to systematically study aerosol–cloud correlations over three anthropogenic aerosol regions and their adjacent oceans, as well as explore the effect of retrieval artifacts and underlying physical mechanisms. This study is confined to warm phase and single-layer clouds without precipitation during the summertime (June, July, and August). Our analysis suggests that cloud effective radius (CER) is positively correlated with aerosol optical depth (AOD) over land (positive slopes), but negatively correlated with aerosol index (AI) over oceans (negative slopes) even with small ranges of liquid water path (quasi-constant). The changes in albedo at the top of the atmosphere (TOA) corresponding to aerosol-induced changes in CER also lend credence to the authenticity of this opposite aerosol–cloud correlation between land and ocean. It is noted that potential artifacts, such as the retrieval biases of both cloud (partially cloudy and 3-D-shaped clouds) and aerosol, can result in a serious overestimation of the slope of CER–AOD/AI. Our results show that collision–coalescence seems not to be the dominant cause for positive slope over land, but the increased CER caused by increased aerosol might further increase CER by initializing collision–coalescence, generating a positive feedback. By stratifying data according to the lower tropospheric stability and relative humidity near cloud top, it is found that the positive correlations more likely occur in the case of drier cloud top and stronger turbulence in clouds, while negative correlations occur in the case of moister cloud top and weaker turbulence in clouds, which implies entrainment mixing might be a possible physical interpretation for such a positive CER–AOD slope.
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Zhang, Cheng Hu, Ting Ting Song, Ju Liu, Hui Juan Xia, and Jian Zhu Wang. "Microbial Activity in Soils of Vegetation-Growing Concrete Slopes." Advanced Materials Research 599 (November 2012): 124–27. http://dx.doi.org/10.4028/www.scientific.net/amr.599.124.
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Natural restoration slope and vegetation-growing concrete slope were selected as plots. Soil water content (SWC), pH, and soil organic matter, total nitrogen content (TN), total organic carbon (TOC), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), basal respiration, microbial quotient and metabolic quotient (qCO2) were analyzed. The main results show that: Soil organic matter, TN and MBC of 0-10 cm soil in the natural restoration slope are significantly lower than that in the vegetation-growing concrete slopes at 0.05 level. Both MBC and MBN show a highly significant positive correlation with soil organic matter and TN. Microbial quotient shows a highly significant negative correlation with TOC and MBN, and shows a significant negative correlation with MBC. The qCO2 shows a highly significant negative correlation with pH, and a significant negative correlation with MBC. The vegetation-growing concrete technology can improve the soil ecosystem in the impaired slope.
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Lu, Xin, and Kang Zuo. "On the slope of hyperelliptic fibrations with positive relative irregularity." Transactions of the American Mathematical Society 369, no. 2 (May 2, 2016): 909–34. http://dx.doi.org/10.1090/tran6682.
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Amoranto, Evan, Brandy Doleshal, and Matt Rathbun. "Additional cases of positive twisted torus knots." Journal of Knot Theory and Its Ramifications 26, no. 12 (October 2017): 1750078. http://dx.doi.org/10.1142/s021821651750078x.
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A twisted torus knot is a knot obtained from a torus knot by twisting adjacent strands by full twists. The twisted torus knots lie in [Formula: see text], the genus 2 Heegaard surface for [Formula: see text]. Primitive/primitive and primitive/Seifert knots lie in [Formula: see text] in a particular way. Dean gives sufficient conditions for the parameters of the twisted torus knots to ensure they are primitive/primitive or primitive/Seifert. Using Dean’s conditions, Doleshal shows that there are infinitely many twisted torus knots that are fibered and that there are twisted torus knots with distinct primitive/Seifert representatives with the same slope in [Formula: see text]. In this paper, we extend Doleshal’s results to show there is a four parameter family of positive twisted torus knots. Additionally, we provide new examples of twisted torus knots with distinct representatives with the same surface slope in [Formula: see text].
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Li, Gang, Shengming Dong, Hao Wang, Yanmei Guan, Patrick Tyler Deja, and Wei Nie. "Effect of ecological restoration on topsoil phosphorus following afforestation on abandoned ponds in northern Chaohu Lake, China." Nature Conservation 53 (June 16, 2023): 1–16. http://dx.doi.org/10.3897/natureconservation.53.97873.
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Afforestation is an approach for ecological restoration. Soil total phosphorus is one of the important ecological and evolutionary elements for carbon cycles and plant growth following afforestation. However, studies on soil total phosphorus of afforestation on abandoned ponds with different slopes are still lacking. Soil total phosphorus and other soil properties from afforestation sites with different slopes were investigated. Soil total phosphorus, total nitrogen, bulk density, soil water contents and pH of poplar (Populus spp.) plantation sites (Slope 1) with a steep slope and pond cypress (Taxodium spp.) plantation sites (Slope 2) with a flat slope were determined. Soil total nitrogen stocks, soil total phosphorus stocks and the ratio of soil total nitrogen to total phosphorus (N:P) were calculated. Results showed that soil bulk density, soil water content, total phosphorus, total phosphorus stocks and total nitrogen stocks of three soil layers at Slope 1 were significantly lower than those of Slope 2. N:P of Slope 1 was significantly higher, but no significant difference of total nitrogen and pH were found between the two sampling sites. Soil bulk density, soil water content and total nitrogen had significant positive relationships with both total phosphorus and total phosphorus stocks. No obvious correlation was found between pH and total phosphorus or total phosphorus stocks. Redundancy analysis (RDA analysis) suggested that soil water content and bulk density had the most important individual effect on total phosphorus and total phosphorus stocks with values at 59.3% and 59.5%, respectively. It is recommended that afforestation on a flat or gentle slope rather than on a steep gradient could be helpful for accumulation of soil total phosphorus and phosphorus stocks and could decrease the risk of soil phosphorus loss, when afforestation is used for ecological restoration.
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Rickli, Christian, Frank Graf, Peter Bebi, Alexander Bast, Bernard Loup, and Brian McArdell. "Schützt der Wald vor Rutschungen? Hinweise aus der WSL-Rutschungsdatenbank." Schweizerische Zeitschrift fur Forstwesen 170, no. 6 (December 1, 2019): 310–17. http://dx.doi.org/10.3188/szf.2019.0310.
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Does the forest provide protection from landslides? Evidence from the WSL Shallow Landslide Database During strong rainfall events, shallow landslides and debris avalanches (hillslope debris flows, or open-slope debris flows) are triggered and sometimes lead to considerable damage. Analysis of damage-causing events show that there are fewer landslides in forested areas compared to non-forested areas, which indicates the generally positive influence of forest vegetation on slope stability. However, these effects depend on the condition of the forest stand and quantification of the effects is difficult. Event documentation contributes to a better understanding of the relevant processes. The information obtained is not only important for the preparation of hazard maps, but also provides valuable insight for assessing the hazard protection provided by the forest. Data from the landslide database of the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) were used to evaluate the influence of the forest on slope stability. Currently, the database contains information on 734 landslides. Of these, 661 were included in the evaluation – 356 landslides in non-forested areas and 305 in forested areas. In areas with slope angles up to 38°, more landslides per unit area are observed in non-forested areas than in forested areas. In areas with steeper slope angles a stabilizing effect of the forest is no longer recognizable. Statistical analyses show that landslides in forested areas are smaller than in non-forested areas and are more frequent on steeper slopes. In general, the landslides become smaller with increasing slope. Multivariate analyses indicate a positive influence of the forest and also somewhat smaller landslides in well-developed forests. Negative effects are evident in non-forested areas and in areas with overly dense forests. In addition to illustrating the importance of the forest condition for slope stability, the paper also discusses how the forest condition can be described.
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FIDDY, M. A., R. P. INGEL, and J. O. SCHENK. "ANISOTROPIC METAMATERIALS FOR FIELD ENHANCEMENT AND NEGATIVE INDEX APPLICATIONS." Journal of Nonlinear Optical Physics & Materials 17, no. 04 (December 2008): 357–66. http://dx.doi.org/10.1142/s0218863508004275.
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1D highly anisotropic periodic structures can exhibit very large internal field enhancements and positive spectral phase slopes. The field enhancement can lead to significant external fields radiating from the structure close to frequencies at which the spectral phase slope changes sign and where an effective negative index regime can occur.
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Sharma, Sharang Rav. "First-Order Event Plane Correlated Directed and Triangular Flow from Fixed-Target Energies at RHIC-STAR." Universe 10, no. 3 (March 1, 2024): 118. http://dx.doi.org/10.3390/universe10030118.
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We report the measurement of first-order event plane-correlated directed flow (v1) and triangular flow (v3) for identified hadrons (π±, K±, and p), net particle (net-K, net-p), and light nuclei (d and t) in Au + Au collisions at sNN = 3.2, 3.5, and 3.9 GeV in the fixed-target mode from the second phase of the beam energy scan (BES-II) program at RHIC-STAR. The v1 slopes at mid-rapidity for identified hadrons and net particles except π+ are found to be positive, implying the effect of dominant repulsive baryonic interactions. The slope of v1 for net-kaon undergoes a sign change from negative to positive at a lower collision energy compared to net-proton. An approximate atomic mass number scaling is observed in the measured v1 slopes of light nuclei at mid-rapidity, which favors the nucleon coalescence mechanism for the production of light nuclei. The v3 slope for all particles decreases in magnitude with increasing collision energy, suggesting a notable integrated impact of the mean-field, baryon stopping, and collision geometry at lower collision energies.
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Sittadewi, Euthalia Hanggari. "FUNCTION OF INTERCEPTION, EVAPOTRANSPIRATION AND ROOT REINFORCEMENT OF PLANT ON SLOPE STABILIZATION." Jurnal Sains dan Teknologi Mitigasi Bencana 15, no. 1 (June 30, 2020): 19–26. http://dx.doi.org/10.29122/jstmb.v15i1.4116.
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The ability of plants to carry out the functions of interception, evapotranspiration and root reinforcement provides an effective and contributes to an increase in slope stability. Canopy has a role in the process of interception related to the reduction of amount the infiltrated water and the rapid fulfilment of soil moisture. Through the evapotranspiration mechanism, plants can reduce pore water pressure in the soil so that the trigger force for landslides can be reduced and the soil will be more stable. The roots mechanically strengthen the soil, through the transfer of shear stresses in the soil into tensile resistance in the roots. Roots also bind soil particles and increase surface roughness, thereby reducing the process of soil displacement or erosion. There is a positive relationship between the density of the tree canopy with the value of rainfall interception, evapotranspiration with a decrease in pore water pressure in the soil and the ability of root anchoring and binding with an increase in soil shear strength, indicating that the function of interception, evapotranspiration and strengthening of plant roots have a positive effect on increasing slope stability. Plants selection that considers the level of interception, the rate of evapotranspiration and root reinforcement by adjusting environmental and slopes conditions will determine the success of slope stabilization efforts by vegetative methods.Keywords : interception, evapotranspiration, root reinforcement, slope stabilization.
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Mahannopkul, Krairoj, and Chollada Kanjanakul. "Some Approaches to the Prediction of Permeability Parameters in a Finite Element Program for Early Warning." Civil Engineering Journal 8, no. 12 (December 1, 2022): 3854–65. http://dx.doi.org/10.28991/cej-2022-08-12-014.
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Recently, landslides often occurred in natural soil slopes in the tropical region, which correlate with the rainy season. Rainfall infiltration leads to groundwater level fluctuations. The increased positive pore-water pressures due to rainfall influence have affected the properties and behavior of the unsaturated soil slope. In this research, the Finite Element Method of SEEP/W and SLOPE/W analyzes the factor safety of the slope affected by pore water pressure change due to rainfall. The Soil Water Characteristic Curve (SWCC) and Hydraulic Conductivity function were obtained from sieve analysis and Atterberg's limit. In addition, unsaturated soil properties from the UNSODA code are estimated based on grain-size distribution using the SWRC program. The study area is in Khanom District, southern Thailand. The results show that the soil slope at the site became unstable on November 18, 2021, with F.S. = 1.0, which agrees well with the date of the disaster. In conclusion, the slope stability analysis without the parameters from the unsaturated soil hydraulic database (UNSODA) leads to the F.S. value being higher than the actual value, and the alarm estimation would be inaccurate. Doi: 10.28991/CEJ-2022-08-12-014 Full Text: PDF
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Simoneau, Guy G., Richard W. Marklin, and Joseph E. Berman. "Effect of Computer Keyboard Slope on Wrist Position and Forearm Electromyography of Typists Without Musculoskeletal Disorders." Physical Therapy 83, no. 9 (September 1, 2003): 816–30. http://dx.doi.org/10.1093/ptj/83.9.816.
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Background and Purpose. Positioning a computer keyboard with a downward slope reduces wrist extension needed to use the keyboard and has been shown to decrease pressure in the carpal tunnel. However, whether a downward slope of the keyboard reduces electromyographic (EMG) activity of the forearm muscles, in particular the wrist extensors, is not known. Subjects and Methods. Sixteen experienced typists participated in this study and typed on a conventional keyboard that was placed on slopes at angles of 7.5, 0, −7.5, and −15 degrees. Electromyographic activity of the extensor carpi ulnaris (ECU), flexor carpi ulnaris (FCU), and flexor carpi radialis (FCR) muscles was measured with surface electrodes, while the extension and ulnar deviation angles of the right and left wrists were measured with electrogoniometers. Results. Wrist extension angle decreased from approximately 12 degrees of extension while typing on a keyboard with a 7.5-degree slope to 3 degrees of flexion with the keyboard at a slope of −15 degrees. Although the differences were in the range of 1% to 3% of maximum voluntary contraction (MVC), amplitude probability distribution function (APDF) of root-mean-square EMG data points from the ECU, FCU, and FCR muscles varied across keyboard slopes. Discussion and Conclusion. Wrist extension decreased as the keyboard slope decreased. Furthermore, a slight decrease in percentage of MVC of the ECU muscle was noted as the keyboard slope decreased. Based on biomechanical modeling and published work on carpal tunnel pressure, both of these findings appear to be positive with respect to comfort and fatigue, but the exact consequences of these findings on the reduction or prevention of injuries have yet to be determined. The results may aid physical therapists and ergonomists in their evaluations of computer keyboard workstations and in making recommendations for interventions with regard to keyboard slope angle.
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Bernhardson, Andrew S., Zachary S. Aman, Grant J. Dornan, Bryson R. Kemler, Hunter W. Storaci, Alex W. Brady, Gilberto Y. Nakama, and Robert F. LaPrade. "Tibial Slope and Its Effect on Force in Anterior Cruciate Ligament Grafts: Anterior Cruciate Ligament Force Increases Linearly as Posterior Tibial Slope Increases." American Journal of Sports Medicine 47, no. 2 (January 14, 2019): 296–302. http://dx.doi.org/10.1177/0363546518820302.
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Background: Previous work has reported that increased tibial slope is directly correlated with increased anterior tibial translation, possibly predisposing patients to higher rates of anterior cruciate ligament (ACL) tears and causing higher rates of ACL graft failures over the long term. However, the effect of changes in sagittal plane tibial slope on ACL reconstruction (ACLR) graft force has not been well defined. Purpose/Hypothesis: The purpose of this study was to quantify the effect of changes in sagittal plane tibial slope on ACLR graft force at varying knee flexion angles. Our null hypothesis was that changing the sagittal plane tibial slope would not affect force on the ACL graft. Study Design: Controlled laboratory study. Methods: Ten male fresh-frozen cadaveric knees had a posterior tibial osteotomy performed and an external fixator placed for testing and accurate slope adjustment. Following ACLR, specimens were compressed with a 200-N axial load at flexion angles of 0°, 15°, 30°, 45°, and 60°, and the graft loads were recorded through a force transducer clamped to the graft. Tibial slope was varied between −2° and 20° of posterior slope at 2° increments under these test conditions. Results: ACL graft force in the loaded testing state increased linearly as slope increased. This effect was independent of flexion angle. The final model utilized a 2-factor linear mixed-effects regression model and noted a significant, highly positive, and linear relationship between tibial slope and ACL graft force in axially loaded knees at all flexion angles tested (slope coefficient = 0.92, SE = 0.08, P < .001). Significantly higher graft force was also observed at 0° of flexion as compared with all other flexion angles for the loaded condition (all P < .001). Conclusion: The authors found that tibial slope had a strong linear relationship to the amount of graft force experienced by an ACL graft in axially loaded knees. Thus, a flatter tibial slope had significantly less loading of ACL grafts, while steeper slopes increased ACL graft loading. Our biomechanical findings support recent clinical evidence of increased ACL graft failure with steeper tibial slope secondary to increased graft loading. Clinical Relevance: Evaluation of the effect of increasing tibial slope on ACL graft force can guide surgeons when deciding if a slope-decreasing proximal tibial osteotomy should be performed before a revision ACLR. Overall, as slope increases, ACL graft force increases, and in our study, flatter slopes had lower ACL graft forces and were protective of the ACLR graft.
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Gao, Haiqiang, Shuguang Liu, Weizhi Lu, Andrew R. Smith, Rubén Valbuena, Wende Yan, Zhao Wang, et al. "Global Analysis of the Relationship between Reconstructed Solar-Induced Chlorophyll Fluorescence (SIF) and Gross Primary Production (GPP)." Remote Sensing 13, no. 14 (July 18, 2021): 2824. http://dx.doi.org/10.3390/rs13142824.
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Solar-induced chlorophyll fluorescence (SIF) is increasingly known as an effective proxy for plant photosynthesis, and therefore, has great potential in monitoring gross primary production (GPP). However, the relationship between SIF and GPP remains highly uncertain across space and time. Here, we analyzed the SIF (reconstructed, SIFc)–GPP relationships and their spatiotemporal variability, using GPP estimates from FLUXNET2015 and two spatiotemporally contiguous SIFc datasets (CSIF and GOSIF). The results showed that SIFc had significant positive correlations with GPP at the spatiotemporal scales investigated (p < 0.001). The generally linear SIFc–GPP relationships were substantially affected by spatial and temporal scales and SIFc datasets. The GPP/SIFc slope of the evergreen needleleaf forest (ENF) biome was significantly higher than the slopes of several other biomes (p < 0.05), while the other 11 biomes showed no significant differences in the GPP/SIFc slope between each other (p > 0.05). Therefore, we propose a two-slope scheme to differentiate ENF from non-ENF biome and synopsize spatiotemporal variability of the GPP/SIFc slope. The relative biases were 7.14% and 11.06% in the estimated cumulative GPP across all EC towers, respectively, for GOSIF and CSIF using a two-slope scheme. The significantly higher GPP/SIFc slopes of the ENF biome in the two-slope scheme are intriguing and deserve further study. In addition, there was still considerable dispersion in the comparisons of CSIF/GOSIF and GPP at both site and biome levels, calling for discriminatory analysis backed by higher spatial resolution to systematically address issues related to landscape heterogeneity and mismatch between SIFc pixel and the footprints of flux towers and their impacts on the SIF–GPP relationship.
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Lv, Da Wei, Bao Guo Shi, Fei Wang, and Guan Jun Xu. "Analysis of Reliability on Slope Stability Based on Safety Factor." Applied Mechanics and Materials 353-356 (August 2013): 130–36. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.130.
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A mechanical model for Sarma method was built based on a sliding of simple non-homogeneous rock slope as the research object. The relationship between the lateral positive pressure on block and the critical acceleration coefficient were gotten according to the rock slope block static equilibrium conditions. Then the critical acceleration coefficient formula was deduced. So that the coefficient of slopes security and stability under the conditions of the earthquake intensity were receieved.By using the functional relation between the slopes security and stability coefficient and the critical acceleration coefficient, a monotonously decreases function relationships between the rock slopes security and stability coefficient and the critical acceleration coefficient drowned by the calculation and analysis was gotten. The results show that, this method does not need iteration when compared with the traditional Sarma method; hence a convergence problem does not exist. It also can simplify the calculation and reduce a large number of calculations, the calculated results can meet the requirements after a number of numerical examples analysis.
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Zhang, Xiaoying, Lin Li, Sheng Jin, Yihai Tan, and Yangfeng Wu. "Impact Analysis of Slope on the Head Loss of Gas-Liquid Two-Phase Flow in Siphon Pipe." Water 11, no. 5 (May 25, 2019): 1095. http://dx.doi.org/10.3390/w11051095.
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Through an analysis of the head loss of the gas–liquid two-phase flow in a siphon pipe, this paper measures the bubble velocity, pressure drop, and gas fraction under various conditions. The influence of varied head, gradient, and installation heights of the pipe on the air mass movement, head loss, and resistance coefficient of the gas–liquid two-phrase flow is analyzed on the basis of the test results. The results show that the bubble velocity reaches its minimum on the flat slope, and the velocity on the positive slope is higher than that on the reverse slope. The head loss of pipelines in both the positive slope and reverse slope increases as the gradient increases, while the head loss on the reverse slope is larger than that on the positive slope under the same gradient. When the gas fraction α is between 8% and 30%, the resistance coefficient λm is related to the gradient, gas fraction, and the Reynolds number Re. Furthermore, λm is proportionate to α and inversely proportionate to i of the bottom slope and the Re number. The calculation formula of the resistance coefficient λm under various gradients within the scope of the above gas fraction is derived on the basis of the test data, while the relative error is controlled within the allowable range.
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Vongkhamho, Simone, Akihiro Imaya, Kazukiyo Yamamoto, Chisato Takenaka, and Hiroyuki Yamamoto. "Influence of Topographic Conditions on Teak Growth Performance in Mountainous Landscapes of Lao PDR." Forests 13, no. 1 (January 14, 2022): 118. http://dx.doi.org/10.3390/f13010118.
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Teak is a globally valuable hardwood tree species, as its growth performance is important for timber productivity. The purpose of this study was to establish an effective management system for teak plantations in the Lao PDR. Using diameter at breast height (DBH) and height growth as significant indicators of growth performance, we investigated the relationship between tree growth curve parameters of teak and topographic conditions. Stem analysis data for 81 sample trees (three trees selected in canopy trees with predominant height in each plot) were examined for growth performance using the Mitscherlich growth function. The results of Spearman’s partial rank correlation indicated that the upper limits of DBH and tree height growth had significant negative correlations with the slope gradient and stand density. The curvature of DBH and tree height growth curves showed significant positive correlations with the slope form. Moreover, the elevation and slope gradient showed significant negative correlations with the curvature of tree height growth curve. However, the time lag of DBH growth showed a significant negative correlation with the slope position, while the slope gradient was positively correlated with the time lag of tree height growth. These results suggest that teak planted at lower slopes has faster growth rates and that there is an interaction with the gentle concave slope of this area.
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Prokushkin, A. S., T. Kajimoto, S. G. Prokushkin, W. H. McDowell, A. P. Abaimov, and Y. Matsuura. "Climatic factors influencing fluxes of dissolved organic carbon from the forest floor in a continuous-permafrost Siberian watershed." Canadian Journal of Forest Research 35, no. 9 (September 1, 2005): 2130–40. http://dx.doi.org/10.1139/x05-150.
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Fluxes of dissolved organic carbon (DOC) in forested watersheds underlain by permafrost are likely to vary with changes in climatic regime that increase soil moisture and temperature. We examined the effects of temporal and spatial variations in soil temperature and moisture on DOC fluxes from the forest floor of contrasting north- and south-facing slopes in central Siberia. DOC fluxes increased throughout the growing season (JuneSeptember) on both slopes in 2002 and 2003. The most favorable combination of moisture content and temperature (deepest active soil layer) occurred in September, and we believe this was the primary driver of increased DOC concentrations and flux in autumn. Total DOC flux for JuneSeptember was 12.617.6 g C·m2 on the south-facing slope and 4.68.9 g C·m2 on the north-facing slope. DOC concentrations in forest floor leachates increased with increasing temperature on the north-facing slope, but were almost unaffected by temperature on the south-facing slope. Our results suggest that water input in midseason from melting of ice or precipitation events is the primary factor limiting DOC production. Significant positive correlations between amounts of precipitation and DOC flux were found on both slopes. Dilution of DOC concentrations by high precipitation volumes was observed only for the forest floor leachates collected from the north-facing slope. Our results suggest that global warming will result in increased DOC production in forest floors of permafrost regions, and that precipitation patterns will play an important role in determining the magnitude of these changes in DOC flux as well as its interannual variability. However, the longer-term response of soils and DOC flux to a warming climate will be driven by changes in vegetation and microbial communities as well as by the direct results of temperature and moisture conditions.
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OIKAWA, SHIN, and YASUO ITAZAWA. "Gill and Body Surface Areas of the Carp in relation to Body Mass, With Special Reference To The Metabolism-Size Relationship." Journal of Experimental Biology 117, no. 1 (July 1, 1985): 1–14. http://dx.doi.org/10.1242/jeb.117.1.1.
Full textAbstract:
The relationships of resting metabolism per unit mass of body to gill and body surface areas were examined by measuring gill, body surface and fin areas of carp ranging from 0.0016 to 2250g. There was a triphasic allometry for the relationship between gill area and body mass: during the prelarval (0.0016–0.003 g) and postlarval (0.003–0.2g) stages there was a positive allometry (slopes of 7.066 and 1.222, respectively), during the juvenile and later stages (0.2–2250 g) there was a negative allometry with a slope of 0.794. There was a diphasic negative allometry for the relationship between surface area of the body or the fins and body mass, with a slope of 0.596 or 0.523 during the larval stage and 0.664 or 0.724 during the juvenile and later stages, respectively. Except for the 3rd phase (juvenile to adult) of gill area, these slopes were significantly different (P<0.01) from the slope for the relationship between resting metabolism and body mass of intact carp (0.84; value from Winberg, 1956). It is considered, therefore, that gill, body surface and fin areas do not directly regulate the resting metabolism of the fish, in the larval stage at least.
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Rahardjo, H., T. T. Lee, E. C. Leong, and R. B. Rezaur. "Response of a residual soil slope to rainfall." Canadian Geotechnical Journal 42, no. 2 (April 1, 2005): 340–51. http://dx.doi.org/10.1139/t04-101.
Full textAbstract:
Rainfall-induced landslides are a common problem in residual soil slopes of the tropics. It is widely known that rainfall-induced slope failures are mainly caused by infiltration of rainwater; however, the response of a residual soil slope to infiltration is not fully understood. The difficulties lie in the quantification of the flux boundary condition across the slope surface with respect to infiltration and its effect on the pore-water pressure conditions in the slope. Therefore, it is important to understand the response of a slope to different rainfall conditions and the resulting changes in pore-water pressures and water contents. A residual soil slope in Singapore was instrumented with pore-water pressure, water content, and rainfall measuring devices, and studies were carried out under natural and simulated rainfalls. Results indicate that significant infiltration may occur in a residual soil slope during a rainfall. Small total rainfalls can contribute a larger infiltration percentage than large total rainfalls. The percentage of infiltration usually decreases with increasing total rainfalls. The study has indicated the existence of a threshold rainfall of about 10 mm for runoff generation to commence. Infiltration during wet periods may lead to the development of positive pore-water pressures as a consequence of a perched water table condition. Matric suctions are recovered gradually during dry periods due to redistribution. Soil water contents tend to be higher near the toe of the slope than at the crest irrespective of rainfall events, indicating subsurface movement of water in the downslope direction. The study has also indicated a correlation between rainfall amount and relative increase in pore-water pressure. The results can be used to quantify the flux boundary conditions required for the seepage analyses associated with rainfall-induced slope failures.Key words: infiltration, pore-water pressure, water content, residual soil, rainfall-induced slope failures.