Magnetic superelevation design of Halbach permanent magnet guideway for high-temperature superconducting maglev

Science.gov (United States)

Lei, Wuyang; Qian, Nan; Zheng, Jun; Huang, Huan; Zhang, Ya; Deng, Zigang

2017-07-01

To improve the curve negotiating ability of high-temperature superconducting (HTS) maglev system, a special structure of magnetic superelevation for double-pole Halbach permanent magnet guideway (PMG) was designed. The most significant feature of this design is the asymmetrical PMG that forms a slanting magnetic field without affecting the smoothness of the PMG surface. When HTS maglev vehicle runs through curves with magnetic superelevation, the vehicle will slant due to asymmetry in magnetic field and the flux-pinning effect of onboard HTS bulks. At the same time, one component of the levitation force provides a part of the centripetal force that reduces lateral acceleration of the vehicle and thus enhances its curve negotiating ability. Furthermore, the slant angle of magnetic superelevation can be adjusted by changing the materials and the thickness of the added permanent magnets. This magnetic superelevation method, together with orographic uplift, can be applied to different requirements of PMG designs. Besides, the applicability of this method would benefit future development of high-speed HTS maglev system.

Elevated and super-elevated CO2 differ in their interactive effects with nitrogen availability on fruit yield and quality of cucumber.

Science.gov (United States)

Dong, Jinlong; Xu, Qiao; Gruda, Nazim; Chu, Wenying; Li, Xun; Duan, Zengqiang

2018-02-25

Elevated carbon dioxide (CO 2 ) and nitrogen (N) availability can interactively promote cucumber yield, but how the yield increase is realized remains unclear, whilst the interactive effects on fruit quality are unknown. In this study, cucumber plants (Cucumis sativus L. cv. Jinmei No. 3) were grown in a paddy soil under three CO 2 concentrations - 400 (ambient CO 2 ), 800 (elevated CO 2 , eCO 2 ) and 1200 µmol mol -1 (super-elevated CO 2 ) - and two N applications - 0.06 (low N) and 0.24 g N kg -1 soil (high N). Compared with ambient CO 2 , eCO 2 increased yield by 106% in high N but the increase in total biomass was only 33%. This can result from greater carbon translocation to fruits from other organs, indicated by the increased biomass allocation from stems and leaves, particularly source leaves, to fruits and the decreased concentrations of fructose and glucose in source leaves. Super-elevated CO 2 reduced the carbon allocation to fruits thus yield increase (71%). Additionally, eCO 2 also increased the concentrations of fructose and glucose in fruits, maintained the concentrations of dietary fiber, phosphorus, potassium, calcium, magnesium, sulfur, manganese, copper, molybdenum and sodium, whilst it decreased the concentrations of nitrate, protein, iron, and zinc in high N. Compared with eCO 2 , super-elevated CO 2 can still improve the fruit quality to some extent in low N availability. Elevated CO 2 promotes cucumber yield largely by carbon allocation from source leaves to fruits in high N availability. Besides a dilution effect, carbon allocation to fruits, carbohydrate transformation, and nutrient uptake and assimilation can affect the fruit quality. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

The dynamics of a channel-fed lava flow on Pico Partido volcano, Lanzarote

Science.gov (United States)

Woodcock, Duncan; Harris, Andrew

2006-09-01

A short length of channel on Pico Partido volcano, Lanzarote, provides us the opportunity to examine the dynamics of lava flowing in a channel that extends over a sudden break in slope. The 1 2-m-wide, 0.5 2-m-deep channel was built during the 1730 1736 eruptions on Lanzarote and exhibits a sinuous, well-formed channel over a steep (11° slope) 100-m-long proximal section. Over-flow units comprising smooth pahoehoe sheet flow, as well as evidence on the inner channel walls for multiple (at least 11) flow levels, attest to unsteady flow in the channel. In addition, superelevation is apparent at each of the six bends along the proximal channel section. Superelevation results from banking of the lava as it moves around the bend thus causing preferential construction of the outer bank. As a result, the channel profile at each bend is asymmetric with an outer bank that is higher than the inner bank. Analysis of superelevation indicates flow velocities of ~8 m s 1. Our analysis of the superelevation features is based on an inertia-gravity balance, which we show is appropriate, even though the down-channel flow is in laminar flow. We use a viscosity-gravity balance model, together with the velocities calculated from superelevation, to obtain viscosities in the range 25 60 Pa s (assuming that the lava behaved as a Newtonian liquid). Estimated volume fluxes are in the range 7 12 m3 s 1. An apparent down-flow increase in derived volume flux may have resulted from variable supply or bulking up of the flow due to vesiculation. Where the channel moves over a sharp break in slope and onto slopes of ~6°, the channel becomes less well defined and widens considerably. At the break of slope, an elongate ridge extends across the channel. We speculate that this ridge was formed as a result of a reduction in velocity immediately below the break of slope to allow deposition of entrained material or accretion of lava to the channel bed as a result of a change in flow regime or depth.

Field Observation of Setup

National Research Council Canada - National Science Library

Yemm, Sean

2004-01-01

Setup is defined as the superelevation of mean water surface within the surfzone and is caused by the reduction in wave momentum shoreward of the breaking point and compensating positive pressure gradient...

Effects of different elevated CO2 concentrations on chlorophyll contents, gas exchange, water use efficiency, and PSII activity on C3 and C4 cereal crops in a closed artificial ecosystem.

Science.gov (United States)

Wang, Minjuan; Xie, Beizhen; Fu, Yuming; Dong, Chen; Hui, Liu; Guanghui, Liu; Liu, Hong

2015-12-01

Although terrestrial CO2 concentrations [CO2] are not expected to reach 1000 μmol mol(-1) (or ppm) for many decades, CO2 levels in closed systems such as growth chambers and greenhouses can easily exceed this concentration. CO2 levels in life support systems (LSS) in space can exceed 10,000 ppm (1 %). In order to understand how photosynthesis in C4 plants may respond to elevated CO2, it is necessary to determine if leaves of closed artificial ecosystem grown plants have a fully developed C4 photosynthetic apparatus, and whether or not photosynthesis in these leaves is more responsive to elevated [CO2] than leaves of C3 plants. To address this issue, we evaluated the response of gas exchange, water use efficiency, and photosynthetic efficiency of PSII by soybean (Glycine max (L.) Merr., 'Heihe35') of a typical C3 plant and maize (Zea mays L., 'Susheng') of C4 plant under four CO2 concentrations (500, 1000, 3000, and 5000 ppm), which were grown under controlled environmental conditions of Lunar Palace 1. The results showed that photosynthetic pigment by the C3 plants of soybean was more sensitive to elevated [CO2] below 3000 ppm than the C4 plants of maize. Elevated [CO2] to 1000 ppm induced a higher initial photosynthetic rate, while super-elevated [CO2] appeared to negate such initial growth promotion for C3 plants. The C4 plant had the highest ETR, φPSII, and qP under 500-3000 ppm [CO2], but then decreased substantially at 5000 ppm [CO2] for both species. Therefore, photosynthetic down-regulation and a decrease in photosynthetic electron transport occurred by both species in response to super-elevated [CO2] at 3000 and 5000 ppm. Accordingly, plants can be selected for and adapt to the efficient use of elevated CO2 concentration in LSS.

Channel Evolution Following Avulsion: an Example from the Yellow River Delta

Science.gov (United States)

Zheng, S.

2017-12-01

Long-term field observation of morphological adjustments of rivers following avulsions is lacked when studying the evolution of avulsive channel on deltas. Avulsion at the Yellow River Delta (YRD) is frequent with average lifespan of channels of only about a decade. The Qing-shui-gou channel, the recent lobe on the YRD, provides a rare opportunity for investigating channel evolution following artificial avulsion. The reasons for its longer lifespan also needs investigation of the channel evolution. In this study, we comprehensively analyzed the geomorphic adjustment of the channel based on filed survey data during 1976-2014. The evolution of the channel was impacted by anthropogenic activities, including artificial avulsion at the downstream channel reaches in 1996, alteration of runoff and sediment load through Water and Sediment Regulation Scheme (WSRS), construction of levees and dikes. Analysis on channel geometry showed that avulsions in 1976 and in 1996 both caused short-term (1 2 years) erosion at the upstream channel reaches. Following the avulsion in 1976, massive aggradation occurred at the channel reaches at the downstream of the avulsion point. A single-thread channel gradually formed, widened and enlarged as channel bed under-cut on the deposition material. As delta extended seaward and the longitudinal slope decreased with time, aggradation occurred and an alluvial ridge formed. The ratio of lateral slope to the longitudinal slope (i.e. gradient advantage) and the relative super-elevation of the channel were calculated to estimate the possibility of avulsion at the channel in the late 1990. Results showed that the slope ratio was greater than 20 locally and super-elevation near its critical value for avulsion. The fact, that natural avulsion did not occurred despite of high values of gradient advantage and super elevation, may indicate that they are not sufficient conditions for avulsion at highly human-controlled rivers, where channel boundaries are

GIS Data Based Automatic High-Fidelity 3D Road Network Modeling

Science.gov (United States)

Wang, Jie; Shen, Yuzhong

2011-01-01

3D road models are widely used in many computer applications such as racing games and driving simulations_ However, almost all high-fidelity 3D road models were generated manually by professional artists at the expense of intensive labor. There are very few existing methods for automatically generating 3D high-fidelity road networks, especially those existing in the real world. This paper presents a novel approach thai can automatically produce 3D high-fidelity road network models from real 2D road GIS data that mainly contain road. centerline in formation. The proposed method first builds parametric representations of the road centerlines through segmentation and fitting . A basic set of civil engineering rules (e.g., cross slope, superelevation, grade) for road design are then selected in order to generate realistic road surfaces in compliance with these rules. While the proposed method applies to any types of roads, this paper mainly addresses automatic generation of complex traffic interchanges and intersections which are the most sophisticated elements in the road networks

Normal pregnancy: mechanisms underlying the paradox of a ouabain-resistant state with elevated endogenous ouabain, suppressed arterial sodium calcium exchange, and low blood pressure

Science.gov (United States)

Jacobs, Brandiese E.; Liu, Yong; Pulina, Maria V.; Golovina, Vera A.

2012-01-01

Endogenous cardiotonic steroids (CTS) raise blood pressure (BP) via vascular sodium calcium exchange (NCX1.3) and transient receptor-operated channels (TRPCs). Circulating CTS are superelevated in pregnancy-induced hypertension and preeclampsia. However, their significance in normal pregnancy, where BP is low, is paradoxical. Here we test the hypothesis that vascular resistance to endogenous ouabain (EO) develops in normal pregnancy and is mediated by reduced expression of NCX1.3 and TRPCs. We determined plasma and adrenal levels of EO and the impact of exogenous ouabain in pregnancy on arterial expression of Na+ pumps, NCX1.3, TRPC3, and TRPC6 and BP. Pregnant (embryonic day 4) and nonpregnant rats received infusions of ouabain or vehicle. At 14–16 days, tissues and plasma were collected for blotting and EO assay by radioimmunoassay (RIA), liquid chromatography (LC)-RIA, and LC-multidimensional mass spectrometry (MS3). BP (−8 mmHg; P vs. nonpregnant (0.6 ± 0.08 nM; P endogenous and exogenous ouabain is mediated by suppressed NCX1.3 and reduced sensitivity of events downstream of Ca2+ entry. The mechanisms of EO resistance and the impaired fetal and placental growth due to elevated ouabain may be important in pregnancy-induced hypertension (PIH) and preeclampsia (PE). PMID:22245773

Fatigue life estimation of MD36 and MD523 bogies based on damage accumulation and random fatigue theory

International Nuclear Information System (INIS)

Younesian, Davood; Solhmirzaei, Ali; Gachloo, Alireza

2009-01-01

Bogies are one of the multifunctional parts of trains which are extremely subjected to random loads. This type of oscillating and random excitation arises from irregularities of the track including rail surface vertical roughness, rail joints, variance in super-elevation, and also wheel imperfections like wheel flats and unbalancy. Since most of the prementioned sources have random nature, a random based theory should be applied for fatigue life estimation of the bogie frame. Two methods of fatigue life estimation are investigated in this paper. The first approach which is being implemented in time domain is based on the damage accumulation (DA) approach. Using Monte-Carlo simulation algorithm, the rail surface roughness is generated. Finite element (FE) model of the bogie is subjected to the generated random excitation in the first approach and the stress time histories are obtained, and consequently the fatigue life is estimated by using the rain-flow algorithm. In the second approach, the fatigue life is estimated in frequency domain. Power spectral density (PSD) of the stress is obtained by using the FE model of the bogie frame and the fatigue life is estimated using Rayleigh technique in random fatigue theory. A comprehensive parametric study is carried out and effects of different parameters like the train speeds and level of the rail surface vertical roughness on the estimated fatigue life are investigated

Analysis of the form vault temple bearing by the laser apparatus LEICA TCR 305

Directory of Open Access Journals (Sweden)

Ľudovít Kovanič, jr.

2007-06-01

Full Text Available As an object of mapping we choosed some of churches as an object of mapping. Ve determined the aisle of Rozalia church in Košice by means using the apparatus Leica TCR 305. The oblique transverse profile was measured. Making use horizontal and vertical lenght components we selected those that defined the beggining, course and the end of the oblique ceilling arch. On the basis of five paired data into a rectangular coordinate system of the vertical plane with the begining in the point of arch origin. The coordinate xi defined the stationing and the coordinate yi defined the height, resp. the superelevation from the apparatus horizont to the arch points securing that the whole course of the arch is retained regularly. First we considered the possibility of circle. The aisle of Rozalia church in Košice. We determined different radiuses using connecting lines of selected points (cords, however it is not important, for the arch. Therefore we considered the solution of the arch shape through a parabola.The comparison of results was realized by the mathematic-statistical methods. Parameters of regression were calculated by the method of least squares .We tried to analyze the curve of this arch using also the method of mathematically defined second grade, curves , namely circles and elipses.

Parameter Deduction and Accuracy Analysis of Track Beam Curves in Straddle-type Monorail Systems

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Xiaobo Zhao

2015-12-01

Full Text Available The accuracy of the bottom curve of a PC track beam is strongly related to the production quality of the entire beam. Many factors may affect the parameters of the bottom curve, such as the superelevation of the curve and the deformation of a PC track beam. At present, no effective method has been developed to determine the bottom curve of a PC track beam; therefore, a new technique is presented in this paper to deduce the parameters of such a curve and to control the accuracy of the computation results. First, the domain of the bottom curve of a PC track beam is assumed to be a spindle plane. Then, the corresponding supposed top curve domain is determined based on a geometrical relationship that is the opposite of that identified by the conventional method. Second, several optimal points are selected from the supposed top curve domain according to the dichotomy algorithm; the supposed top curve is thus generated by connecting these points. Finally, one rigorous criterion is established in the fractal dimension to assess the accuracy of the assumed top curve deduced in the previous step. If this supposed curve coincides completely with the known top curve, then the assumed bottom curve corresponding to the assumed top curve is considered to be the real bottom curve. This technique of determining the bottom curve of a PC track beam is thus proven to be efficient and accurate.

Physiological Disorders in Closed Environment-Grown Crops for Space Life Support

Science.gov (United States)

Wheeler, Raymond; Morrow, Robert

Crop production for life support systems in space will require controlled environments where temperature, humidity, CO2, and light might differ from natural environments where plants evolved. Physiological disorders, i.e., abnormal plant growth and development, can occur under these controlled environments. Among the most common of these disorders are Ca deficiency injuries such as leaf tipburn (e.g., lettuce), blossom-end-rot in fruits (e.g., tomato and pepper), and internal tissue necrosis in fruits or tubers (e.g., cucumber and potato). Increased Ca nutrition to the plants typically has little effect on these disorders, but slowing overall growth or providing better air circulation to increase transpiration can be effective. A second common disorder is oedema or intumescence, which appears as callus-like growth or galls on leaves (e.g., sweetpotato, potato, pepper, and tomato). This disorder can be reduced by increasing the near UV radiation ( 300-400 nm) to the plants. Leaf injury and necrosis can occur under long photoperiods (e.g., tomato, potato, and pepper) and at super-elevated (i.e., ¿ than 4000 mol mol-1) CO2 concentrations (e.g., soybean, potato, and radish), and these can be managed by reducing the photoperiod and CO2 concentration, respectively. Lack of blue light in the spectrum (e.g., under red LEDs or LPS lamps) can result in leggy growth and/or leaves lacking in chlorophyll (e.g., wheat, bean, and radish). Volatile organic compounds (VOCs), most commonly ethylene, can accumulate in tightly closed systems and result in a variety of negative responses. Most of these disorders can be mitigated by altering the environmental set-points or by using more resistant cultivars.

A nonlinear model of flow in meandering submarine and subaerial channels

Science.gov (United States)

Imran, Jasim; Parker, Gary; Pirmez, Carlos

1999-12-01

A generalized model of flow in meandering subaqueous and subaerial channels is developed. The conservation equations of mass and momentum are depth/layer integrated, normalized, and represented as deviations from a straight base state. This allows the determination of integrable forms which can be solved at both linear and nonlinear levels. The effects of various flow and geometric parameters on the flow dynamics are studied. Although the model is not limited to any specific planform, this study focuses on sine-generated curves. In analysing the flow patterns, the turbidity current of the subaqueous case is simplified to a conservative density flow with water entrainment from above neglected. The subaqueous model thus formally corresponds to a subcritical or only mildly supercritical mud-rich turbidity current. By extension, however the analysis can be applied to a depositional or erosional current carrying sand that is changing only slowly in the streamwise direction. By bringing the subaqueous and subaerial cases into a common form, flow behaviour in the two environments can be compared under similar geometric and boundary conditions. A major difference between the two cases is the degree of superelevation of channel flow around bends, which is modest in the subaerial case but substantial in the subaqueous case. Another difference concerns Coriolis effects: some of the largest subaqueous meandering systems are so large that Coriolis effects can become important. The model is applied to meander bends on the youngest channel in the mid-fan region of the Amazon Fan and a mildly sinuous bend of the North-West Atlantic Mid-Ocean Channel. In the absence of specific data on the turbid flows that created the channel, the model can be used to make inferences about the flow, and in particular the range of values of flow velocity and sediment concentration that would allow the growth and downfan migration of meander bends.

Stratigraphic Stacking of Deepmarine Channel Levee Turbidites: Scales of Cyclicity and their Origin. Examples from the Laingsburg Fm. (Karoo, South Africa) and the Rosario Fm. (Baja, Mexico)

Science.gov (United States)

Kane, I. A.; Hodgson, D.

2009-12-01

Thinning upwards of the turbidite beds that form deepmarine channel levees is a common motif reported from modern and recent levees on the seafloor, from subsurface examples, and from outcropping ancient examples. Because levees are thought to be built by deposition from turbidity currents superelevated over their channel form, the volume and style of overbank deposition are controlled primarily by the relationship between levee height (i.e., thalweg to crest) and flow thickness, determining the amount of overspill. Thus stratigraphic variability of turbidite thickness is explained by some change in either or both of those factors, which may arise autocyclicly or allocyclicly. Variation in the ratio of intra-channel and extra-channel deposition can be an autocyclic stratigraphic response, e.g., in bypass dominated systems, thalweg aggradation may be retarded with respect to levee aggradation, hence as levee relief increases, flows become more confined and, given a relatively narrow range of flow sizes, the volume of overbank flow and deposit thickness decrease with stratigraphic height. However, the same stratigraphic response of the levee may occur due to allocyclic flow magnitude variation, i.e., through decreasing flow magnitude. In both the autocyclic and allocyclic case the stratigraphic response of the levee may be one of thinning upwards, even if the overall system response may be one of progradation (autocyclic bypassing case) or retrogradation (allocyclic decreasing flow magnitude case), with entirely different connotations for sequence stratigraphic interpretation. Here we report examples of different scales of bed thickness cyclicity (both thickening and thinning upward cycles superimposed by smaller scale cycles) within levees of the Rosario Formation, Baja California, Mexico, and from the Laingsburg Formation, Karoo, South Africa, and, together with published examples, discuss criteria for the recognition, and drivers of, autocyclic and allocyclic bed

On the required complexity of vehicle dynamic models for use in simulation-based highway design.

Science.gov (United States)

Brown, Alexander; Brennan, Sean

2014-06-01

This paper presents the results of a comprehensive project whose goal is to identify roadway design practices that maximize the margin of safety between the friction supply and friction demand. This study is motivated by the concern for increased accident rates on curves with steep downgrades, geometries that contain features that interact in all three dimensions - planar curves, grade, and superelevation. This complexity makes the prediction of vehicle skidding quite difficult, particularly for simple simulation models that have historically been used for road geometry design guidance. To obtain estimates of friction margin, this study considers a range of vehicle models, including: a point-mass model used by the American Association of State Highway Transportation Officials (AASHTO) design policy, a steady-state "bicycle model" formulation that considers only per-axle forces, a transient formulation of the bicycle model commonly used in vehicle stability control systems, and finally, a full multi-body simulation (CarSim and TruckSim) regularly used in the automotive industry for high-fidelity vehicle behavior prediction. The presence of skidding--the friction demand exceeding supply--was calculated for each model considering a wide range of vehicles and road situations. The results indicate that the most complicated vehicle models are generally unnecessary for predicting skidding events. However, there are specific maneuvers, namely braking events within lane changes and curves, which consistently predict the worst-case friction margins across all models. This suggests that any vehicle model used for roadway safety analysis should include the effects of combined cornering and braking. The point-mass model typically used by highway design professionals may not be appropriate to predict vehicle behavior on high-speed curves during braking in low-friction situations. However, engineers can use the results of this study to help select the appropriate vehicle dynamic

Transcriptional and metabolic insights into the differential physiological responses of arabidopsis to optimal and supraoptimal atmospheric CO2.

Directory of Open Access Journals (Sweden)

Fatma Kaplan

Full Text Available BACKGROUND: In tightly closed human habitats such as space stations, locations near volcano vents and closed culture vessels, atmospheric CO(2 concentration may be 10 to 20 times greater than Earth's current ambient levels. It is known that super-elevated (SE CO(2 (>1,200 µmol mol(-1 induces physiological responses different from that of moderately elevated CO(2 (up to 1,200 µmol mol(-1, but little is known about the molecular responses of plants to supra-optimal [CO(2]. METHODOLOGY/PRINCIPAL FINDINGS: To understand the underlying molecular causes for differential physiological responses, metabolite and transcript profiles were analyzed in aerial tissue of Arabidopsis plants, which were grown under ambient atmospheric CO(2 (400 µmol mol(-1, elevated CO(2 (1,200 µmol mol(-1 and SE CO(2 (4,000 µmol mol(-1, at two developmental stages early and late vegetative stage. Transcript and metabolite profiling revealed very different responses to elevated versus SE [CO(2]. The transcript profiles of SE CO(2 treated plants were closer to that of the control. Development stage had a clear effect on plant molecular response to elevated and SE [CO(2]. Photosynthetic acclimation in terms of down-regulation of photosynthetic gene expression was observed in response to elevated [CO(2], but not that of SE [CO(2] providing the first molecular evidence that there appears to be a fundamental disparity in the way plants respond to elevated and SE [CO(2]. Although starch accumulation was induced by both elevated and SE [CO(2], the increase was less at the late vegetative stage and accompanied by higher soluble sugar content suggesting an increased starch breakdown to meet sink strength resulting from the rapid growth demand. Furthermore, many of the elevated and SE CO(2-responsive genes found in the present study are also regulated by plant hormone and stress. CONCLUSIONS/SIGNIFICANCE: This study provides new insights into plant acclimation to elevated and SE [CO

Complex Channel Avulsion in the Meghna River Foodplain During the Mid to Late Holocene: The Potential Effect of Tectonic and Co-Seismic Uplift

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Dunham, A.; Grall, C.; Mondal, D. R.; Steckler, M. S.; Rajapara, H.; Kumar, B.; Philibosian, B.; Akhter, S. H.; Singhvi, A. K.

2016-12-01

Channel migrations and river avulsions in deltaic river systems are mainly driven by differential changes of surface topography, such as the superelevation of channels due to sedimentation. In addition to such autocyclic processes, tectonic events, such as earthquakes, may also lead to avulsions from sudden uplift. The eastern part of the Ganges-Brahmaputra-Meghna Delta (GBMD) is underlain by the blind megathrust of the IndoBurma subduction zone. In this region we investigate a 100 km long sinuous abandoned channel of the Meghna River. Immediately south of the channel, it has been previously shown that the topography is slightly higher than on the rest of the Delta and there is an oxidized Holocene exposure surface. Part of the Titas River flows northward from this area into the abandoned channel belt, opposite of the southward flowing rivers of the delta. We provide results from a detailed investigation of this abandoned channel of the Meghna River using stratigraphic logs of hand-drilled wells, resistivity profiles, sediment analyses and OSL and C14 dating, The OSL ages to be presented constrain the possible date of the event. We employ numerical modeling to evaluate the hypothesis that the co-seismic uplift associated to an earthquake can trigger the channel migration. Our modeling approach aims to estimate the co-seismic uplift associated with potential seismic events using an elastic Coulomb's dislocation model. The geometry fault in our model is estimated using geologic and GPS constraints with standard elastic parameters (Young's modulus = 80 GPa; Poisson's ratio = 0.3). We explored different potential earthquakes geometries that involve the megathrust, a splay fault, or the megathrust terminating in the splay. The magnitude and distribution of co-seismic slip are also varied between a rupture length of 112.5km and 180km along a 225km long fault. We show that any class of models can produce the amount of uplift (1-2 m) necessary for triggering the river

A new modelling framework and mitigation measures for increased resilience to flooding

Science.gov (United States)

Valyrakis, Manousos; Alexakis, Athanasios; Solley, Mark

2015-04-01

Flooding in rivers and estuaries is amongst the most significant challenges our society has yet to tackle effectively. Use of floodwall systems is one of the potential measures that can be used to mitigate the detrimental socio-economical and ecological impacts and alleviate the associated costs of flooding. This work demonstrates the utility of such systems for a case study via appropriate numerical simulations, in addition to conducting scaled flume experiments towards obtaining a better understanding of the performance and efficiency of the flood-wall systems. At first, the results of several characteristic inundation modeling scenarios and flood mitigation options, for a flood-prone region in Scotland. In particular, the history and hydrology of the area are discussed and the assumptions and hydraulic model input (model geometry including instream hydraulic structures -such as bridges and weirs- river and floodplain roughness, initial and boundary conditions) are presented, followed by the model results. Emphasis is given on the potential improvements brought about by mitigating flood risk using flood-wall systems. Further, the implementation of the floodwall in mitigating flood risk is demonstrated via appropriate numerical modeling, utilizing HEC-RAS to simulate the effect of a river's rising stage during a flood event, for a specific area. The later part of this work involves the design, building and utilization of a scaled physical model of a flood-wall system. These experiments are carried out at one of the research flumes in the Water Engineering laboratory of the University of Glasgow. These involve an experimental investigation where the increase of force applied on the floodwall is measured for different degrees of deflection of the water in the stream, under the maximum flow discharge that can be carried through without exceeding the floodwall height (and accounting for the effect of super-elevation). These results can be considered upon the

Spatial and temporal controls of atoll island inundation: implications for urbanized atolls in the Marshall Islands.

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Ford, M.; Becker, J. M.; Merrifield, M. A.

2012-12-01

Atoll islands are highly vulnerable to a range of inundation hazards. The impacts of such hazards are expected to be magnified as a result of continued sea-level rise. Both recent and historic inundation events provide unique insights into the requisite conditions necessary to initiate island inundation. A number of recent and historic inundation events are presented in order to examine the oceanographic and meteorological conditions driving inundation of a densely populated, urbanized atoll in the central Pacific. Analysis of inundation events suggests that a number of key drivers contribute to the spatial and temporal extent of island inundation, with unique degrees of predictability and resultant impact signatures apparent on island geomorphology and local anthropogenic activities. Results indicate three distinct drivers of inundation hazards exist. Firstly, tropical storms and typhoons elevate sea level through inverse barometric setup, wind setup and a range of wave driven processes and have caused considerable impact on atolls within the Marshall Islands. Secondly, super-elevated sea level conditions resulting from the combination of seasonal high tides and quasi-cyclical La Nina conditions drive inundation of low-lying lagoon facing coastal areas. Thirdly, long period swell conditions, typically generated by distant storms, can elevate reef-flat water levels through wave setup and infragravity wave oscillations. Such wave conditions can over wash the ocean-facing island ridge, often inundating large sections of the island. Reef-flat wave conditions are tidally modulated, with inundation events typically occurring around high tide. However, the two most recent destructive swell-driven inundation events have occurred while tide levels were significantly lower than spring tide levels, suggesting high water levels are not a necessary prerequisite for wave-driven inundation. The different modes of inundation are discussed and grounded within recent and historic

A finite volume solver for three dimensional debris flow simulations based on a single calibration parameter

Science.gov (United States)

von Boetticher, Albrecht; Turowski, Jens M.; McArdell, Brian; Rickenmann, Dieter

2016-04-01

illustrated with lab-scale and large-scale experiments. A large-scale natural landslide event down a curved channel is presented to show the model performance at such a scale, calibrated based on the observed surface super-elevation.