WorldWideScience
 
 
1

New insights into the ground thermal regime of talus slopes with permafrost below the timberline  

Science.gov (United States)

In the central Alps permafrost can be expected above 2400 m a.s.l., at altitudes where mean annual air temperatures are below -1° C. However, isolated permafrost occurrences are present in north-exposed talus slopes, far below the timberline, where mean annual air temperatures are positive. Driving factors are assumed to be a low income of solar radiation, a thick organic layer with high insulation capacities as well as the thermally induced chimney effect (Wakonigg, 1996). Investigated are three talus slopes with permafrost in the Swiss Alps that differ with regard to elevation level, talus material, humus characteristics and vegetation composition as well as the mean annual air temperatures. Aim is to achieve a deeper understanding of the factors determining the site-specific thermal regime, as well as the spatially limited and temporally highly variable permafrost occurrences in vegetated talus slopes. Focus is not solely on the question of why permafrost exists at these sites, but also why permafrost does not exist in the immediate surroundings. To detect the temporal variability and spatial heterogeneity of the permafrost occurrences, electrical resistivity tomography monitoring, seismic refraction tomography monitoring, and quasi-3D ERT were applied. To determine the ground thermal regime, air-, ground surface-, and humus temperatures, as well as temperatures within vents of the chimneys were recorded. Furthermore, humus characteristics (thickness, -temperature and -moisture) were mapped in permafrost-affected slope areas and in the immediate surroundings. To test the correlation between solar radiation, permafrost distribution, and humus/vegetation composition, digital elevation models were used to calculate the income of solar radiation. The areal extent of the permafrost bodies coincide precisely with slope sections where the organic layer is thickest, a consistent moss cover is present, and where temperatures at the transition between humus layer and talus material are lowest. The interaction of factors driving the ground thermal regime turned out to be more complex than assumed with differences between the investigated sites. Besides convective heat transport of the chimney effect, conductive heat flow within the humus layer strongly influences the ground thermal regime. Supercooling of the talus material in winter and autumn is aggravated by a high thermal conductivity of the organic material under frozen and wet conditions. The preservation of permafrost is favoured by the high insulation capacity of dry organic material in summer and by a prolonged zero-curtain period of up to 3 months - driven by high water-storage capacity of the organic material - that buffers the propagation of warm temperatures into the subsurface in spring. The income of solar radiation at the foot of the slope does not state a major driving factor for the occurrence of permafrost. Variability is low between areas with and without permafrost. In fact, differences were detected upslope, below the rock-walls, with summer-values being lowest in areas above the permafrost occurrences. It must be assumed that this affects the thermal circulation of the chimney effect during summer and favours the persistence of frozen ground in spatially limited slope areas.

Schwindt, Daniel; Kneisel, Christof

2013-04-01

2

Snow cover and ground surface temperature on a talus slope affected by mass movements. Veleta cirque, Sierra Nevada, Spain  

Science.gov (United States)

This paper analyses the thermal ground behaviour on an alpine talus slope located at the foot of the north wall of the glacial cirque on the Pico del Veleta (3398 m, 37°03'21''N, 3°21'57''W, MAAT: -0,4°C) in Sierra Nevada, SE Spain. There are frequent mass movements on this talus slope, particularly in its central section, caused by the abundant presence of fine-grained sediment and by the water from snowmelt and/or ice degradation in the ground or permafrost (Gómez et al., 2003). To determine the snowmelt pattern and ocurrence of permafrost, a continuous ground surface temperature was kept by installing 6 mini-loggers (HOBO Pendant) along the descending profile of the central talus, which is 170 m long with altitudes ranging from 3180 m at the higher end to 3085 m at the lower end. A thermal borehole was also installed at a depth of 2 m at the base of the slope on an active rock glacier. The results obtained for the period October 2008 - September 2009 show that, in contrast to alpine talus slopes (Luetschg et. al., 2004; Lambiel and Pieracci, 2008), the upper part of the slope is characterized by mean annual ground surface temperatures (MAGST) lower than at the base of the talus, possibly due to the effect of the shadow of the cirque wall. The MAGST oscillate between 0.592°C at the station near the slope apex (S2) and 1.836°C at the station near the base (S5). In winter-spring, when the talus slope is covered with snow, the GST are stabilized at all stations between mid-October and early November. The minimum GST, which express the BTS conditions, oscillate between 0.232 and 0.01°C, depending on the month, with lowest values recorded during the month of April. Only one station (S3, mid-slope) recorded negative values (max. value : - 0.549°C in December and - 0.211 in April ). In summer, the snow disappears fairly quickly between mid- and late July on the intermediate stretch of the talus slope (S3, S4, S6), where the majority of the flows detected occur. In the mid-upper part (S5, S2) the thaw occurs in mid-August. The GST data provide evidence of the current absence of permafrost along the talus slope profile, although some years ago it was detected using BTS methods (Gómez et al., 2003. Gómez-Ortiz, A., Palacios, D., Luengo, E., Tanarro, L. M.; Schulte, L. and Ramos, M., 2003. Talus instability in a recent deglaciation area and its relationship to buried ice and snow cover evolution (Picacho del Veleta, Sierra Nevada, Spain). Geografisca Annaler 85 A (2), 165-182. Lambiel, C. and Pieracci, K. 2008. Permafrost distribution in talus slopes located within the alpine periglacial belt, Swiss Alps. Permafrost and Periglac. Process. 19: 293-304 Luetschg, M.; Stoeckli, M.; Lehning, M.; Haeberli, W., and Ammann, W. 2004. Temperatures in two boreholes at Flüela Pass, Eastern Swiss Alps: the effect of snow redistribution on permafrost distribution patterns in high mountain areas. Permafrost and Periglac. Process. 15: 283-297. Research funded by CGL2009-7343 project, Government of Spain.

Tanarro, L. M.; Palacios, D.; Gómez-Ortiz, A.; Salvador-Franch, F.

2012-04-01

3

Paediatric talus fracture.  

LENUS (Irish Health Repository)

Paediatric talus fractures are rare injuries resulting from axial loading of the talus against the anterior tibia with the foot in dorsiflexion. Skeletally immature bone is less brittle, with higher elastic resistance than adult bone, thus the paediatric talus can sustain higher forces before fractures occur. However, displaced paediatric talus fractures and those associated with high-energy trauma have been associated with complications including avascular necrosis, arthrosis, delayed union, neurapraxia and the need for revision surgery. The authors present the rare case of a talar neck fracture in a skeletally immature young girl, initially missed on radiological review. However, clinical suspicion on the part of the emergency physician, repeat examination and further radiographic imaging revealed this rare paediatric injury.

Byrne, Ann-Maria

2012-01-01

4

Evidences of winter ascending air circulation throughout talus slopes and rock glaciers situated in the lower belt of alpine discontinuous permafrost (Swiss Alps)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The winter ascending circulation of air throughout an accumulation of coarse slope sediments (the so-called chimney effect) facilitates the cooling of the ground and even the occurrence of permafrost in the lower part of a deposit. Simultaneously, any freezing is unlikely to occur in the upper part. The chimney effect has been reported to date mainly for cold and sometimes perennially frozen scree slopes situated at low elevations, far below the regional limit of the discontinuous mountain pe...

2005-01-01

5

Primary osteosarcoma of the talus  

International Nuclear Information System (INIS)

Osteosarcoma (OS) of the talus is extremely rare and few cases have been reported in the literature. We present a acse of 33-year-old male with painfull sweeling of his left ankle joint. He underwent several radiological diagnostic modalities that showed osteolytic lesion in the posterior aspect of the left talus associated with new bone formation projecting from the posteriorimedial aspect of that bone. His chest x-ray showed multiple rounded lung metastases, some of them showed calcifications. Open biopsy was performed. The histopathology confirmed the diagnosis of osteoblastic OS of the talus. (author)

2008-01-01

6

Vanad sõbrad: Poola president õhtustas Ärma talus  

Index Scriptorium Estoniae

President Toomas Hendrik Ilves võõrustas 28. märtsil 2011 Viljandimaal Ärma talus Poola presidenti Bronislaw Komorowskit. Poola riigipea abikaasa Anna Komorowska ja proua Evelin Ilves külastasid Tallinnas ka lastekirjanduse keskust, kus esitleti raamatut "Väike Chopin" ning tegid ekskursiooni Tallinna vanalinnas

2011-01-01

7

Osteochondritis dissecans of the talus: diagnosis and treatment in athletes.  

Science.gov (United States)

Osteochondritis dissecans of the talus is a subset of osteochondral lesions of the talus that also includes osteochondral fractures, avascular necrosis, and degenerative arthritis. Osteochondral lesions of the talus can be associated with injury to the ankle. This article discusses the anatomy, pathoanatomy, history, physical examination, imaging, management algorithm, and outcomes of surgical treatment of osteochondral lesions in these patients. This article also presents the authors' recommended surgical technique. PMID:24698042

Talusan, Paul G; Milewski, Matthew D; Toy, Jason O; Wall, Eric J

2014-04-01

8

On the contemporary morphodynamics of an alpine talus cone and the granulometry and morphometry of its surface particles  

Science.gov (United States)

Talus cones are important sediment stores in high mountain basins. They act as both sediment sinks for rock fall debris and sources for debris flows and the fluvial system and are thus important components of alpine sediment cascades. After a 50000 m3 rock fall event in 2007, the morphodynamics of the talus cone "Am Steingerümpel" (Reintal valley, Wetterstein Mountains, Bavarian Alps) were studied in great detail, based on the previous investigations of HECKMANN et al. (2012). During a four-year period (2008-2011) the whole study site (rock fall scar and talus cone) was scanned three times with a terrestrial laserscanner (TLS). The TLS-based digital elevation models were used for change detection, calculating sediment input, reworking and output and to derive morphological attributes of the talus cone. In 2011 the surface of the talus cone was mapped with differential GPS. On the basis of this mapping 3 different zones of contemporary geomorphological activity were identified: A) Inactive zone: The biggest part of the slope surface has been inactive since the rockfall event in 2007. B) Active zone, dominated by fluvial and debris flow processes: Debris shift mainly occurs at the sides and is driven by fluvial processes during snowmelt or rainstorms. Also small debris flows appear. C) Active zone, rockfall-dominated: Continuous material input from rockfall at the apex of the cone has been recognized. Additionally particle size, shape and sorting of the surficial debris were measured in each zone along selected longitudinal transects. These parameters were related to morphological properties of the cone (e.g. slope, distance from the apex). First results show that particles are very poorly sorted at every point on the surface. At one profile (zone A and B) the typical effects of downslope sorting and downslope increase of sphericity were observed. The cone apex was dissected by fluvial erosion. The particles in one gully show other characteristics than particles on the inactive talus cone. There is no correlation between particle size and distance from the talus apex. Only the sphericity is related to the distance from the apex.

Weber, M.; Bimböse, M.; Schmidt, K.-H.; Morche, D.

2012-04-01

9

A rare case of Aneurysmal Bone Cyst of the Talus  

Directory of Open Access Journals (Sweden)

Full Text Available Talus bone is an unusual location for Aneurysmal Bone Cysts. Although considered benign, it has a locally aggressive behavior making it difficult both from diagnostic and therapeutic point of view. It becomes even more challenging when unusual sites are encountered. We report a rare and challenging case of Aneurysmal Bone Cyst in Talus in a young male patient who was treated with curettage and bone grafting. [Cukurova Med J 2014; 39(4.000: 932-937

Sandesh S. Madi

2014-08-01

10

A probabilistic approach for the design of slopes in opencast mines. Application to the coal mine of Carmaux (France). Apport d'une approche probabiliste de la stabilite pour la conception des talus de mine a ciel ouvert. Application a la mine de Carmaux, France  

Energy Technology Data Exchange (ETDEWEB)

Slope stability problem in opencast mines is one that is often encountered by geotechnical engineers in the design of slopes in jointed rock masses. To resolve this problem, several elments such as the geometrical and the geotechnical parameters of the fracture set of the rock mass have to be considered. In this paper, the characterization of the statistical distribution of geometrical fracture parameters enables the simulation of the rock massive and thus provides a realistic approach to the analysis of failure mechanisms that may affect the rock mass. Computer programs were developed and applied to the opencast coal mine of Carmaux (France). Test results led to the proposal of different slope angles and bench widths for different slope orientations in the mine. 9 refs., 5 figs., 3 tabs.

Afilaka, J.O.; Cojean, R. (Mining University of Jos, Jos (Nigeria). Dept. of Geology)

1989-10-01

11

President Ilves võõrustas Ärma talus Poola riigipead / Raimo Poom  

Index Scriptorium Estoniae

Poola president Lech Kaczynski ja tema abikaasa Maria Kaczynska külastasid president Toomas Hendrik Ilvest ja proua Evelin Ilvest Ärma talus Viljandimaal. Eesti riigipea rõhutas kohtumisel peamiselt Euroopa Liidu ja NATO teemasid ning väljendas rahulolematust Ignalina tuumajaama projekti kulgemise viisi ja tempo üle

Poom, Raimo

2008-01-01

12

Closed total dislocation of talus without any accompanying fractures.  

Science.gov (United States)

Total talar dislocation, ie, disruption of the talus from the calcaneus, navicula, and tibia, is a rare and severe injury. We present a case of closed peritalar dislocation without any accompanying fractures and, thus, discuss the conflicts encountered in this rare injury. A 25-year-old male patient presented with severe pain, swelling, and deformity in his right ankle within 30 minutes of a fall from a height. There were no wounds around the ankle. Radiographs revealed that the talus was disrupted from the calcaneus, navicula, and tibia moving in the anterolateral direction. No accompanying fractures were seen in the talus or in surrounding bones. After an unsuccessful closed reduction attempt, a further decision was open reduction. It was seen that the interposed joint capsula was preventing reduction. After reduction, stability of the ankle was checked and found to be satisfactory, so no fixation material was used. It has been 2 years since the first injury, and the patient is functioning well, with no pain. The ankle has the same range of motion as the unaffected side. No sign of an avascular necrosis or sclerosis is seen on the final radiographs. Closed total dislocation of the talus without any accompanying fractures is a rare entity. The injury is open to various important complications, such as avascular necrosis, infection in patients with open wounds, and arthritic changes. To achieve a good outcome, early reduction of the dislocation has key importance. PMID:23328856

Gursu, Sarper; Sahin, Vedat; Demir, Bilal; Yildirim, Timur

2013-01-01

13

MR imaging of osteochondral lesion of the talus  

International Nuclear Information System (INIS)

Forty feet from 33 patients with osteochondral lesions of the talus were examined using magnetic resonance (MR) imaging. All lesions were shown as low signal intensities on T1-weighted images. Thus T1-weighted imaging was found to be useful in early and definitive diagnosis of osteochondral lesions of the talus. Movability of osteochondral fragments was reflected by the high signal rim between the fragments and matrix on T2-weighted images. The low signal rim between the osteochondral fragments and matrix consisted of fibrous tissues. The high signal rim consisted of not only synovial flulid but also fibrous granulomatous tissues. Some of the matrix was seen as comparatively diffuse low signal intensity on T1-weighted images, probably reflecting either reactive osteosclerosis to abnormal stress due to osteochondral fragments or healing process of osteonecrosis. (N.K.)

1994-09-01

14

MR imaging of osteochondral lesion of the talus  

Energy Technology Data Exchange (ETDEWEB)

Forty feet from 33 patients with osteochondral lesions of the talus were examined using magnetic resonance (MR) imaging. All lesions were shown as low signal intensities on T1-weighted images. Thus T1-weighted imaging was found to be useful in early and definitive diagnosis of osteochondral lesions of the talus. Movability of osteochondral fragments was reflected by the high signal rim between the fragments and matrix on T2-weighted images. The low signal rim between the osteochondral fragments and matrix consisted of fibrous tissues. The high signal rim consisted of not only synovial flulid but also fibrous granulomatous tissues. Some of the matrix was seen as comparatively diffuse low signal intensity on T1-weighted images, probably reflecting either reactive osteosclerosis to abnormal stress due to osteochondral fragments or healing process of osteonecrosis. (N.K.).

Kumai, Tsukasa; Takakura, Yoshinori; Nakayama, Seiichiro; Tanaka, Yasumasa; Takaoka, Takanori; Tamai, Susumu [Nara Medical Univ., Kashihara (Japan)

1994-09-01

15

A Case Report of Sequela of Operation of Talus Osteonecrosis  

Directory of Open Access Journals (Sweden)

Full Text Available Objective : The clinic study or report about Oriental Medical treatment about osteonecrosis is very insufficient. Therefore, we report a case about a sequela of operation of talus osteonecrosis treated by Oriental Medical treatments. Methods : The patient was managed by bee venom and Carthami Flos Herbal-Acupuncture, Sa-am and body acupucture, oxibustion, physical theraphy and herbal medicine. We evaluated the patient through Visual Analogue Scale(VAS. Results : After 25 days of treatment, the patient showed that clinical symptoms was decreased and VAS changed from 10 to 2. Conclusion : In this case, Oriental Medical treatments for a sequela of operation of talus osteonecrosis was effective. But further studies are required to confirm the effect of these methods

Choi Sung-Hun

2006-02-01

16

Congenital vertical talus: Treatment by reverse ponseti technique  

Directory of Open Access Journals (Sweden)

Full Text Available Background: The surgery for idiopathic congenital vertical talus (CVT can lead to stiffness, wound complications and under or over correction. There are sporadic literature on costing with mixed results. We describe our early experience of reverse ponseti technique. Materials and methods: Four cases (four feet of idiopathic congenital vertical talus (CVT which presented one month after birth were treated by serial manipulation and casting, tendoachilles tenotomy and percutaneous pinning of talonavicular joint. An average of 5.2 (range - four to six plaster cast applications were required to correct the forefoot deformity. Once the talus and navicular were aligned based on the radiographic talus-first metatarsal axis, percutaneous fixation of the talo-navicular joint with a Kirschner wire, and percutaneous tendoachilles tenotomy under anesthesia was performed following which a cast was applied with the foot in slight dorsiflexion. Results: The mean follow-up period for the four cases was 8.5 months (6-12 months. At the end of the treatment all feet were supple and plantigrade but still using ankle foot orthosis (AFO. The mean talocalcaneal angle was 70 degrees before treatment and this reduced to 31 degrees after casting. The mean talar axis first metatasal base angle (TAMBA angle was 60° before casting and this improved to 10.5°. Conclusion: Although our follow-up period is small, we would recommend early casting for idiopathic CVT along the same lines as the Ponseti technique for clubfoot except that the forces applied are in reverse direction. This early casting method can prevent extensive surgery in the future, however, a close vigil is required to detect any early relapse.

Bhaskar Atul

2008-01-01

17

Influence of walking with talus taping on the ankle dorsiflexion passive range of motion.  

Science.gov (United States)

[Purpose] This study investigated the effects of walking with talus taping on the ankle dorsiflexion passive range of motion (DF PROM) in individuals with limited ankle DF PROM. [Subjects] Fifteen ankles with limited DF PROM were examined. [Methods] After rigid strapping tape was applied to the ankles from the talus to the calcaneus, progressing posteriorly and inferiorly, the subjects walked on a walkway for 10?min. Using a goniometer, the ankle DF PROM was measured with the knee extended before and after walking with talus taping. The difference in ankle DF PROM between before and after walking with talus taping was analyzed using the paired t-test. [Results] The ankle DF PROM was significantly increased after walking with talus taping. [Conclusion] Our findings indicate that walking with talus taping is effective for increasing the ankle DF PROM in individuals with limited ankle DF PROM. PMID:24259905

Kang, Min-Hyeok; Kim, Ji-Won; Kim, Moon-Hwan; Park, Tae-Jin; Park, Ji-Hyuk; Oh, Jae-Seop

2013-08-01

18

Influence of Walking with Talus Taping on the Ankle Dorsiflexion Passive Range of Motion  

Science.gov (United States)

[Purpose] This study investigated the effects of walking with talus taping on the ankle dorsiflexion passive range of motion (DF PROM) in individuals with limited ankle DF PROM. [Subjects] Fifteen ankles with limited DF PROM were examined. [Methods] After rigid strapping tape was applied to the ankles from the talus to the calcaneus, progressing posteriorly and inferiorly, the subjects walked on a walkway for 10?min. Using a goniometer, the ankle DF PROM was measured with the knee extended before and after walking with talus taping. The difference in ankle DF PROM between before and after walking with talus taping was analyzed using the paired t-test. [Results] The ankle DF PROM was significantly increased after walking with talus taping. [Conclusion] Our findings indicate that walking with talus taping is effective for increasing the ankle DF PROM in individuals with limited ankle DF PROM.

Kang, Min-Hyeok; Kim, Ji-Won; Kim, Moon-Hwan; Park, Tae-Jin; Park, Ji-Hyuk; Oh, Jae-Seop

2013-01-01

19

Sex estimation from the talus in a Thai population.  

Science.gov (United States)

Previous research on sex estimation from the tarsals has shown that the talus is the most sexually dimorphic tarsal bone in most populations. In order to assess the sexing potential of the talus in a Thai population, 252 skeletons (126 male, 126 female) from the Chiang Mai University Skeletal Collection were measured. The sample represents Thai people who come from the local Chiang Mai area and who died within the past ten years. Ten measurements were taken on the left and right tali from each skeleton. Seven of these measurements are similar, or identical, to measurements used by other researchers. Three experimental measurements were also taken. Logistic regression equations were calculated for each measurement, and for pairs of measurements. The individual measurements were also examined using ROC analysis. Averaging the results from both sides, the individual measurements with the highest correct allocation accuracies based on logistic regression analysis were trochlear length (88.2%), trochlear breadth (87.3%), talar length (85.5%), and inferior articular surface length (84.5%). The ROC results followed a similar pattern, with Area Under the Curve values as follows: trochlear length (0.952), inferior articular surface length (0.937), trochlear breadth (0.935), and talar length (0.914). When pairs of measurements were considered by means of logistic regression, four equations produced predicted allocation accuracies greater than 90% - three from the right talus, and one from the left. The highest accuracy on both sides resulted from a combination of the two most sexually dimorphic individual measurements of trochlear length and trochlear breadth. Together, they produced predicted allocation accuracies of 91.3% on the right side, and 91.4% on the left side. Unlike many past studies that have found talar length to be the most sexually dimorphic measurement of the talus, our study found trochlear length and breadth to be the most accurate measurements for distinguishing the sexes. Researchers developing sexing equations for use with other populations should consider including trochlear length and breadth in their analyses. PMID:24794741

Mahakkanukrauh, Pasuk; Praneatpolgrang, Sithee; Ruengdit, Sitthiporn; Singsuwan, Phruksachat; Duangto, Phuwadon; Case, D Troy

2014-07-01

20

Talus osteochondral bruises and defects: diagnosis and differentiation.  

Science.gov (United States)

Acute bone bruises of the talus after ankle injury need to be managed differently from osteochondral defects. Bone bruises have a benign course, but there may be persistent edema. A bone bruise should not delay rehabilitation unless symptoms persist or significant edema is close to the subchondral plate. Osteochondral defects have a less predictable prognosis, and rehabilitation should aim at promoting healing of the subchondral fracture. A period of nonweight bearing reduces the cyclical pressure load through the fissure and promotes healing. Surgery should be reserved for chronic symptomatic lesions or for those patients undergoing lateral ligament reconstruction. PMID:23465947

McCollum, Graham A; Calder, James D F; Longo, Umile Giuseppe; Loppini, Mattia; Romeo, Giovanni; van Dijk, C Niek; Maffulli, Nicola; Denaro, Vincenzo

2013-03-01

 
 
 
 
21

Morphometric Changes in Talus of Club Foot A Gross Observation in Human Foetuses / Cambios Morfométricos en Talus del Pie Zambo, una Observación Macroscópica en Fetos Humanos  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in spanish Para su estudio morfológico fueron disecados ambos pies de seis fetos humanos de distintas edades, uno de los pies era zambo. Seis parámetros morfométricos fueron considerados para la comparación de graves alteraciones anatómicas en los pies normales y deformes; estos fueron: 1. Longitud máxima del [...] talus, 2. Dimensión longitudinal de la cabeza del talus, 3. Ancho troclear anterior, 4. Altura medial máxima del talus, 5. Cuello talar y ángulo calcáneo, 6. Ángulo talocalcáneo. Todos los fetos con pie zambo congénito tienen una deformidad similar del esqueleto del pie. Las anomalías graves observadas fueron el menor tamaño del talus del pie zambo, aumento de la desviación media y retraso en el crecimiento plantar, deformación de la cabeza y región del cuello talar. También se observó una subluxación medial plantar del hueso navicular, con un consecuente deformidad de las facetas articulares de la cabeza del talus. La uniformidad y consistencia de las anomalías anatómicas fueron los rasgos más llamativos en este estudio. Abstract in english Both the feet of six human foetuses of different age groups having unilateral club feet, were dissected for morphological study. Six morphometric parameters considered for comparing gross anatomical changes in normal and deformed feet, were 1-Maximum length of the talus, 2-Longitudinal dimension of [...] head of talus, 3-Anterior trochlear breadth, 4-Maximum medial talar height, 5-Talar neck and calcaneal angle, 6-Talocalcaneal angle. All the foetuses with congenital club feet have almost similar deformity of foot skeleton. The gross anomalies observed were the smaller size of club foot talus and increased medial and planter deviation of a stunted, misshapen head and neck region. A medial plantar subluxation of the navicular bone with a consequent deformity of the articular facets of the talar head was also observed. Uniformity and consistency of anatomical abnormalities were striking features in present study.

, Fazal-ur-Rehman; Nafis A, Faruqi.

22

Morphometric Changes in Talus of Club Foot A Gross Observation in Human Foetuses Cambios Morfométricos en Talus del Pie Zambo, una Observación Macroscópica en Fetos Humanos  

Directory of Open Access Journals (Sweden)

Full Text Available Both the feet of six human foetuses of different age groups having unilateral club feet, were dissected for morphological study. Six morphometric parameters considered for comparing gross anatomical changes in normal and deformed feet, were 1-Maximum length of the talus, 2-Longitudinal dimension of head of talus, 3-Anterior trochlear breadth, 4-Maximum medial talar height, 5-Talar neck and calcaneal angle, 6-Talocalcaneal angle. All the foetuses with congenital club feet have almost similar deformity of foot skeleton. The gross anomalies observed were the smaller size of club foot talus and increased medial and planter deviation of a stunted, misshapen head and neck region. A medial plantar subluxation of the navicular bone with a consequent deformity of the articular facets of the talar head was also observed. Uniformity and consistency of anatomical abnormalities were striking features in present study.Para su estudio morfológico fueron disecados ambos pies de seis fetos humanos de distintas edades, uno de los pies era zambo. Seis parámetros morfométricos fueron considerados para la comparación de graves alteraciones anatómicas en los pies normales y deformes; estos fueron: 1. Longitud máxima del talus, 2. Dimensión longitudinal de la cabeza del talus, 3. Ancho troclear anterior, 4. Altura medial máxima del talus, 5. Cuello talar y ángulo calcáneo, 6. Ángulo talocalcáneo. Todos los fetos con pie zambo congénito tienen una deformidad similar del esqueleto del pie. Las anomalías graves observadas fueron el menor tamaño del talus del pie zambo, aumento de la desviación media y retraso en el crecimiento plantar, deformación de la cabeza y región del cuello talar. También se observó una subluxación medial plantar del hueso navicular, con un consecuente deformidad de las facetas articulares de la cabeza del talus. La uniformidad y consistencia de las anomalías anatómicas fueron los rasgos más llamativos en este estudio.

Fazal-ur-Rehman

2012-03-01

23

CT for diagnosing fractures of the undersurface of the talus and mechanism of injury  

International Nuclear Information System (INIS)

Talus fractures whose fracture lines extend to the subtalar joint, except fractures of the neck and the body of the talus, are defined as fractures of the lower portion of the talus. It is difficult to make a correctly diagnosis of inferior fractures of the talus by plain radiography or tomography alone. The author encountered 12 cases of inferior fractures of the talus between 1989 and 1997, and CT imaging in 2 directions, in the horizontal and frontal plane, was useful in making the diagnosis. The correct diagnosis rate was 100%, and differentiation of the site and extent of the fractures was possible. Based on the CT findings, the fractures were classified into 8 types (fractures of the lateral process of the talus, fractures of the medial tubercle, fractures of the posterior process, and combinations of the above, and comminuted fractures). The mechanism of the injuries was also investigated, and the fractures of the lateral process of the talus seemed to have been caused by excessive eversion force on the ankle joint, with the lateral process becoming trapped between the fibula and the calcaneus. Medial tubercle fractures also seemed to be caused by forcible inversion of the ankle, with the tip of the medial malleous impacting and the medial tubercle being trapped between it and the sustentaculum tali. The comminuted fractures seem to have been caused by axial compression added to various of external forces. (K.H.)

2000-02-01

24

Congenital vertical talus in four generations of the same family  

Energy Technology Data Exchange (ETDEWEB)

This paper presents four generations of a family with radiographically demonstrated congenital vertical talus (CVT) in whom a HOXD10 gene mutation was identified. Some members of the family with this mutation exhibited cavo-varus foot deformity consistent with a Charcot-Marie-Tooth (CMT)-like disorder. Physical examination was performed on nearly all of the affected and unaffected family members. DNA was extracted from blood obtained from 14 subjects who showed radiographic and clinical features of CVT (two of whom also had CMT), from two subjects with features of CMT but not CVT, and from 20 related family members who were clinically normal. Radiographs show the appearance of uncorrected CVT in infancy, in childhood, and in adulthood. DNA analysis revealed a mutation in a HOXD10gene located on chromosome 2 in all of the affected but none of the unaffected family members. There is an autosomal-dominant-inherited mutation with complete penetrance which is found in all members of a pedigree with CVT, some of whom exhibit a CMT-like foot disorder. Radiologic findings vary depending on the severity of involvement, treatment provided and age of the patient. (orig.)

Levinsohn, E. Mark [Crouse Hospital, Department of Medical Imaging, Syracuse (United States); Shrimpton, Antony E. [SUNY Upstate Medical University, Department of Clinical Pathology, Syracuse (United States); Cady, Robert B. [SUNY Upstate Medical University, Department of Pediatrics, Syracuse (United States); Packard, David S. [SUNY Upstate Medical University, Department of Cell and Developmental Biology, Syracuse (United States); Hootnick, David R. [SUNY Upstate Medical University, Department of Pediatrics, Syracuse (United States); SUNY Upstate Medical University, Department of Cell and Developmental Biology, Syracuse (United States); SUNY Upstate Medical University, Department of Orthopedic Surgery, Syracuse (United States)

2004-11-01

25

Rocks Exposed on Slope in Aram Chaos  

Science.gov (United States)

MGS MOC Release No. MOC2-550, 20 November 2003This spectacular vista of sedimentary rocks outcropping on a slope in Aram Chaos was acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on 14 November 2003. Dark piles of coarse talus have come down the slopes as these materials continue to erode over time. Note that there are no small meteor impact craters in this image, indicating that erosion of these outcrops has been recent, if not on-going. This area is located near 2.8oS, 20.5oW. The 200 meter scale bar is about 656 feet across. Sunlight illuminates the scene from the lower right.

2003-01-01

26

Direct coronal computed tomography arthrography of osteochondritis dissecans of the talus  

Energy Technology Data Exchange (ETDEWEB)

Although radiographs, arthrography, tomography, and computed tomography can all be used to diagnose osteochondritis dissecans of the talus, these imaging methods may not demonstrate whether an undisplaced osteochondral fragment has any attachment to the articular cartilage or bony bed of the talus. As lack of such attachment is a relative indication for surgery, we studied the feasibility of using coronal computed tomography (CT) after double contrast arthrography to demonstrate attachment in four patients with osteochondritis dissecans seen on radiographs. Direct coronal CT arthrographic images showed intact articular cartilage in three patients. In the fourth patient, overlying cartilage was virtually absent and contrast tracked beneath the fragment, an appearance that correlated with arthroscopic findings of partial articular cartilage attachment and no union at the osteochondral fracture line. Our initial experience suggests that direct coronal CT arthrography clearly shows the state of attachment of the osteochondritic fragment to the talus.

Heare, M.M.; Gillespy, T. III; Bittar, E.S.

1988-04-01

27

Direct coronal computed tomography arthrography of osteochondritis dissecans of the talus  

International Nuclear Information System (INIS)

Although radiographs, arthrography, tomography, and computed tomography can all be used to diagnose osteochondritis dissecans of the talus, these imaging methods may not demonstrate whether an undisplaced osteochondral fragment has any attachment to the articular cartilage or bony bed of the talus. As lack of such attachment is a relative indication for surgery, we studied the feasibility of using coronal computed tomography (CT) after double contrast arthrography to demonstrate attachment in four patients with osteochondritis dissecans seen on radiographs. Direct coronal CT arthrographic images showed intact articular cartilage in three patients. In the fourth patient, overlying cartilage was virtually absent and contrast tracked beneath the fragment, an appearance that correlated with arthroscopic findings of partial articular cartilage attachment and no union at the osteochondral fracture line. Our initial experience suggests that direct coronal CT arthrography clearly shows the state of attachment of the osteochondritic fragment to the talus. (orig.)

1988-01-01

28

Assessment of gait symmetry for Talus Valgus children based on experimental kinematic analysis  

Science.gov (United States)

The general purpose of this study was to assess the gait symmetry for Talus Valgus deformity based on experimental kinematic analysis. As this foot condition generally occurs in children, the study is focused on two children having five years old, one being healthy, as control subject, and the second one having bilateral Talus Valgus deformity. Kinematic experimental analysis was conducted using Zebris CMS-HS Measuring System. The bilateral symmetry was analyzed using two methods: index of symmetry (SI) calculated for spatio-temporal parameters (stance phase, swing phase, and step length) and kinematic parameter (maximum value of dorsiflexion - plantar flexion angle in the ankle joint), and an unpaired t-test to compare the variation of means values of dorsiflexion - plantar flexion angle in ankle joint for both left and right side. The study evidenced a good bilateral symmetry in case of the control subject and quantified the asymmetry in case of subject with Talus Valgus deformity.

Toth-Tascau, Mirela; Pasca, Oana; Vigaru, Cosmina; Rusu, Lucian

2013-10-01

29

Fraturas do colo do talus: avaliação da reprodutibilidade da classificação de Hawkins / Fractures of the neck of the talus: evaluation of reproducibility of Hawkins´s classification  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Avaliar a reprodutibilidade intra-observador e inter-observador da classificação de Hawkins para fraturas do colo do talus. MÉTODOS: Selecionou-se 20 casos aleatórios de fratura de tálus para serem definidos entre os tipos da classificação por oito cirurgiões ortopédicos, 13 residentes de [...] ortopedia e 15 de radiologia. RESULTADOS: Utilizando o teste estatístico de Landis e Kock foram obtidas médias de 0.627 e 0.668, na primeira e segunda avaliação, respectivamente. Tais valores definem uma concordância satisfatória para a classificação de Hawkins. CONCLUSÃO: Conclui-se que tal classificação é reprodutível entre observadores, possuindo melhores valores conforme maior experiência. Nível de Evidência I, Estudos diagnósticos - Investigação de um exame para diagnóstico. Abstract in english OBJECTIVE: To evaluate the intraobserver and interobserver reproducibility of Hawkins' classification for fractures of the neck of the talus. METHODS: 20 random cases of fracture of the talus were selected, to be defined according to the classification of types by eight orthopedic surgeons, 13 ortho [...] pedic residents and 15 radiology residents. RESULTS: Using the statistical test of Landis and Koch, measurements of 0.627 and 0.668 were obtained in the first and second evaluations, respectively. These values define a satisfactory agreement for Hawkins' classification. CONCLUSION: We conclude that this classification is reproducible between observers, with better values for the more experienced observers. Level of Evidence I, Study Diagnostic - Investigating a diagnostic test.

Drummond Filho, Madson Lobato; Verzani, Marcos Aurélio; Rosa, André Frazão; Pimenta, Ciro Jabur; Grynwald, Jean; Cliquet Junior, Alberto.

30

Simultaneous correction of congenital vertical talus and talipes equinovarus using the Ponseti method.  

Science.gov (United States)

Talipes equinovarus (clubfoot) and congenital vertical talus are commonly seen as isolated deformities in the newborn; however, the case that we described in this article entailed a classic talipes equino varus on the left and a calcaneovalgus on the right. Both deformities were successfully corrected with manipulation therapy and, ultimately, surgical release of the tendoAchillis. PMID:20797881

David, Michael G

2011-01-01

31

[Osteoid osteoma of the talus : A rare cause for pain in the ankle joint].  

Science.gov (United States)

Osteoid osteomas are typically located in the femur and tibia and are mostly easy to diagnose based on patient age, the clinical signs and plain radiographs. In contrast, the diagnosis of osteoid osteomas of the foot is often delayed because of the atypical presentation. We report the case of a 24-year-old patient with persisting pain in the ankle joint over 8 years due to an osteoid osteoma of the talus neck. PMID:23949192

Polzer, H; Polzer, S; Schieker, M; Mutschler, W; Regauer, M

2014-07-01

32

77 - Iveagh Slopes  

...75 - Mourne Mountains76 - Ballyroney Basin77 - Iveagh SlopesIveagh Slopes LandscapeIveagh Slopes Geodiversity...Digital DatasetsStrategic Environmental Assessment (SEA)77 - Iveagh SlopesLast updated: 9 February 2007This...

33

Talus cone activity recorded by tree-rings of Arctic dwarf shrubs: a study case from SW Spitsbergen, Norway  

Science.gov (United States)

Dendrochronological methods were used to determine talus cone activity in the Arctic area. Talus cones are one of the most characteristic geomorphological features of the Svalbad Archipelago. Two species of dwarf shrubs, Salix polaris and Salix reticulata, which belong to the Willow family (Salicaceae), were collected from two talus cones located in the SW Spitsbergen Island. These small creeping shrubs (less than 10 cm tall with stem diameters ranging from 0.5 cm to 1.1 cm) have well developed tree-rings which allow them to be used for dendrochronological research. The age of the dwarf shrubs showed the minimum time during which the cones were disturbed by mass movements. Observations and material analysis indicate that currently the talus cones are active, but their development through debris flow, creep and rock particle slide is observed only episodically. An increased rate of vegetation colonization during the 1980s indicates that geomorphic events were less active in the talus cone area during this time.

Owczarek, Piotr

2010-12-01

34

Effect of Talus Deposit Excavations on Hydrogeochemical Characteristics of Kuvars Spring Water, Maltepe, Istanbul, Turkey  

Directory of Open Access Journals (Sweden)

Full Text Available Spring waters consumed for drinking purposes should be clean and quality. These waters with balanced mineral distribution, which do not contain organic substances, whose physical and chemical caharacteristics comply with certain quality parameters and which do not negatively affect human health are identified as healthy water. Kuvars water is a spring water which is pumped out from the draw well at the Camurluk stream basin of Maltepe province of Istanbul and filled into bottles. The Camurluk stream basin is approximately 4.5 km2. The Camurluk stream basin is sedimentary rocks and talus deposit outcrops. Reaching of trace elements, which is found more in the talus deposit samples than outcropping quartzarenite at the basin, to underground aquifer as ions under effect of rains, water rock interaction, leakage and filtration, is prevented by illite type clay levels existing within the talus deposit stack, which have upto 20 cm thickness. However, negative effects of the excavation that were made at the talus deposit reflect on the hydrologic cycle and chemical compositions of well waters. This effect was at first negatively affected the physical characteristics of the well waters. During the rainy periods, the water in the excavated area which was enriched with respect to the suspended sediments was percolated into the groundwaters from the joints and cracks of the quartzarenite. The turbidity value measured in the well waters of K2 and K3 were determined as 40.3 NTU and 34.2 NTU respectively. Although at the basin, the aquifer of underground water and the well waters being managed are quartzarenite, the fact that water types belonging to well waters differ (they are not same according to the Piper diagram and when the heavy metal content of the water of well numbered KS1 is taken as basis, that some heavy metals such as Al3+, Fe2+, Ni2+, Mn2+ and Cu2+ be enriched 3 to 40 times in KS2 and KS3 well waters, are caused by talus deposit—water interaction at the excavation area. After a rainfall, in the water that became turbid with the water-talus deposit interaction at the excavation area, the water-mineral interaction has caused the limit value for drinking water suggested by World Health Organization (WHO to be exceeded with the Al3+ concentration of 189 ppb detected in KS2 well water and Fe2+ concentration of 185 ppb has caused to approach the drinking water limit value of 200 ppb permitted by World Health Organization (WHO, United States Environmental Protection Agency (EPA, European Union (EU and Turkish Standards (TS. Therefore, at the water basins where bottled spring waters consumed for drinking purposes are produced, technical undertakings that shall disturb the stability of geological units should not be permitted.

Deniz Key

2012-05-01

35

Recurrent parosteal osteosarcoma of the talus in a 2-year-old child  

International Nuclear Information System (INIS)

Parosteal osteosarcoma is an uncommon, low-grade malignant bone tumor and is found in an older age group than conventional osteosarcoma. We present a talar parosteal osteosarcoma that recurred twice in a 2-year-old child. To our knowledge, this is the youngest patient reported with a parosteal osteosarcoma. The talus is an unusual site for parosteal osteosarcoma. Inadequate resection due to a diagnosis of juxtacortical chondroma resulted in recurrence of the tumor. The age of the patient, the thick cartilaginous cap, and well-differentiated trabecular bone all contributed to the critical erroneous diagnosis. (orig.)

1998-03-01

36

Recurrent parosteal osteosarcoma of the talus in a 2-year-old child  

Energy Technology Data Exchange (ETDEWEB)

Parosteal osteosarcoma is an uncommon, low-grade malignant bone tumor and is found in an older age group than conventional osteosarcoma. We present a talar parosteal osteosarcoma that recurred twice in a 2-year-old child. To our knowledge, this is the youngest patient reported with a parosteal osteosarcoma. The talus is an unusual site for parosteal osteosarcoma. Inadequate resection due to a diagnosis of juxtacortical chondroma resulted in recurrence of the tumor. The age of the patient, the thick cartilaginous cap, and well-differentiated trabecular bone all contributed to the critical erroneous diagnosis. (orig.) With 4 figs., 12 refs.

Jee, W.H.; Choe Bo-Young; Choi, K.H.; Shinn Kyung-Sub [Department of Radiology, Catholic University Medical College, Kangnam St. Mary`s Hospital, Seoul (Korea, Republic of); Ok In-Young; Kim Jung-Man [Department of Orthopedic Surgery, Catholic University Medical College, Kangnam St. Mary`s Hospital, Seoul (Korea, Republic of); Choi Yeong-Jin [Department of Pathology, Catholic University Medical College, Kangnam St. Mary`s Hospital, Seoul (Korea, Republic of)

1998-03-01

37

Simulation of River Bluffs and Slip-Off Slopes With a Discrete Particle-Based Model  

Science.gov (United States)

A discrete particle-based model simulates evolution of two-dimensional valley cross sections similar to those produced by bedrock meandering rivers and thereby suggests that characteristic features such as overhanging cliffs and talus slopes are dependent on specific relationships among process rates. Discrete coordinates on a gridded cross-section define locations of particles of intact bedrock, sediment (loose material with half the bulk density of bedrock), water, or air on that grid, and each particle of rock or sediment has a unique (or zero) concentration of terrestrial cosmogenic nuclides (TCNs). Stochastic processes determine both the possible locations of process actions and the results of those actions. Stochastic discharges generate boundary shear stresses, calculated by an approximation to the ray-isovel model, that determine removal probabilities for candidate particles of bedrock or sediment from the boundary of a self-formed channel. An asymmetric probability distribution governs the selection of candidate particles on the wetted perimeter and drives asymmetric fluvial erosion and transport that can undermine adjacent slopes, so that the channel migrates laterally. Sediment is produced from intact bedrock by weathering and rock fall. The latter acts only on candidate bedrock particles that are undermined and exposed at the surface. Weathering produces two sediment particles from one of bedrock, and thereby inflates the surface, when slope-normal random walks from candidate sites on the surface end at bedrock particles, so that the sediment-bedrock interface is irregular and discontinuous. Diffusive transport moves candidate particles on random walks in random directions along the surface, where transition probabilities depend on local topography. TCNs are produced when the randomly situated and oriented random walks of cosmic rays end at bedrock or sediment, and not water, particles. The model produces asymmetric channels and valley cross sections, where the two slopes have contrasting bedrock lowering rates, regolith thicknesses, TCN concentrations, and gradients. In simulated valleys, talus-mantled slopes grade smoothly into steep outer channel banks at the bases of overhanging cliffs, all with small TCN concentrations, and thickly mantled slip-off slopes grade smoothly into shallow inner banks similar to point bars, all with large TCN concentrations. Dimensional analysis suggests, and simulations confirm, relationships that can be tested in the field: cliffs form when bedrock lowering due to weathering is small relative to fluvial bedrock and weathering rate is small relative to fluvial transport capacity; for a given slope length, smaller rock-fall rates produce greater cliff heights; and greater fluvial transport capacity relative to sediment production by bedrock lowering produces thinner talus.

Lancaster, S. T.; Zunka, J. P.; Tucker, G. E.

2013-12-01

38

Slopes of Tilings  

CERN Multimedia

We study here slopes of periodicity of tilings. A tiling is of slope if it is periodic along direction but has no other direction of periodicity. We characterize in this paper the set of slopes we can achieve with tilings, and prove they coincide with recursively enumerable sets of rationals.

Jeandel, Emmanuel

2010-01-01

39

A solitary lesion of talus with mixed sclerotic and lytic changes: Rosai-Dorfman disease of 25 years' duration  

International Nuclear Information System (INIS)

Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) is an unusual form of histiocytic disorder predominantly affecting children and young adults. Bone lesions are infrequent. We describe a 63-year-old woman with a solitary lesion of the talus which was misdiagnosed for 25 years. The patient never had adenopathy or other organ involvement. The radiographic findings were a mixture of sclerotic and lytic changes, an extremely rare and unusual presentation of the disease. (orig.)

2004-04-01

40

Snowboard, wakeboard, dashboard? Isolated fracture of the lateral process of the talus in a high-speed road traffic accident.  

LENUS (Irish Health Repository)

We present a 23-year-old man who sustained an isolated fracture of the lateral process of the talus (LPT) in a head-on vehicle collision at a combined speed of 200 km\\/h. The driver of the other vehicle sustained fatal injuries at the scene. The LPT was openly reduced and fixed with successful outcome at 3 months. This case is unusual in the method of injury, in particular in relation to the isolated relatively minor injury sustained.

Ng, Evangeline Shimei

2013-01-01

 
 
 
 
41

A platyrrhine talus from the early Miocene of Peru (Amazonian Madre de Dios Sub-Andean Zone).  

Science.gov (United States)

The earliest platyrrhines have been documented from the late Oligocene of Bolivia (Salla) and from the early and early middle Miocene of middle and high latitudes (central Chile and Argentinean Patagonia). Recent paleontological field expeditions in Peruvian Amazonia (Atalaya, Cusco; Upper Madre de Dios Basin) have led to the discovery of a new early Miocene locality termed MD-61 ('Pinturan' biochronological unit, ~18.75-16.5 Ma [millions of years ago]). Associated with the typical Pinturan dinomyid rodent Scleromys quadrangulatus, we found a well-preserved right talus of a small-bodied anthropoid primate (MUSM-2024). This new platyrrhine postcranial element displays a combination of talar features primarily found among the Cebidae, and more especially in the Cebinae. Its size approximates that of the talus of some living large marmosets or small tamarins (Cebidae, Callitrichinae). MUSM-2024 would thus document a tiny Saimiri-like cebine, with the body size of a large marmoset. Functionally, the features and proportions of MUSM-2024 indicate that this small primate was arboreal and primarily quadrupedal, agile, with frequent horizontal leaping and vertical clinging in its locomotor repertoire. This small talus is the first platyrrhine fossil to be found from Peru and the earliest primate fossil from northern South America. This new early Miocene taxon could be a stem cebid, thereby providing new evidence on the existence of some long-lived clades of modern platyrrhines. PMID:22974538

Marivaux, Laurent; Salas-Gismondi, Rodolfo; Tejada, Julia; Billet, Guillaume; Louterbach, Mélanie; Vink, Jochem; Bailleul, Julien; Roddaz, Martin; Antoine, Pierre-Olivier

2012-11-01

42

Imaging of fractures of the lateral process of the talus, a frequently missed diagnosis  

International Nuclear Information System (INIS)

Although if fractures of the lateral process of the talus (LPT) have been considered rare the widespread diffusion in snowboard practice has resulted in a dramatic increase in their frequency. If unrecognized they can result in secondary osteoarthritis of the ankle and/or talo-calcaneal joints and chronic pain and stiffness. Due to the complex anatomy of the region, these fractures are difficult to detect by standard radiographs. A high degree of suspicion is then necessary to diagnose them. Once suspected on the basis of physical examination and/or non concluding radiographs, computed tomography (CT) is the best modality to confirm the diagnosis and accurately appreciate the number of the fragments and their position which have therapeutic consequences (medical vs. surgical treatment). A better knowledge of these lesions seems necessary to the general radiologist to allow an early diagnosis in order to avoid chronic sequel. The purpose of this article is to report three additional cases of LPT fractures and discuss their pathogenesis, diagnosis and treatment

2003-07-01

43

Imaging of fractures of the lateral process of the talus, a frequently missed diagnosis  

Energy Technology Data Exchange (ETDEWEB)

Although if fractures of the lateral process of the talus (LPT) have been considered rare the widespread diffusion in snowboard practice has resulted in a dramatic increase in their frequency. If unrecognized they can result in secondary osteoarthritis of the ankle and/or talo-calcaneal joints and chronic pain and stiffness. Due to the complex anatomy of the region, these fractures are difficult to detect by standard radiographs. A high degree of suspicion is then necessary to diagnose them. Once suspected on the basis of physical examination and/or non concluding radiographs, computed tomography (CT) is the best modality to confirm the diagnosis and accurately appreciate the number of the fragments and their position which have therapeutic consequences (medical vs. surgical treatment). A better knowledge of these lesions seems necessary to the general radiologist to allow an early diagnosis in order to avoid chronic sequel. The purpose of this article is to report three additional cases of LPT fractures and discuss their pathogenesis, diagnosis and treatment.

Bonvin, Florent; Montet, Xavier; Copercini, Michele; Martinoli, Carlo; Bianchi, Stefano E-mail: stefano.bianchi@hcuge.ch

2003-07-01

44

Elastic slopes and diffraction  

International Nuclear Information System (INIS)

It is well known that elastic hadronic slopes grow with energy and appear sizeably larger when measured very close to t=0 than at intermediate t-values. This has been confirmed by the recent anti-p p measurements at the CERN SPS-Collider. By comparing the data with a formula derived recently which gives the slope as a function of the four momentum transfer squared t and of the average multiplicity we argue that all the basic properties of hadronic slopes may be attributed to the role of multiparticle unitarity, i.e. to diffraction

1984-01-01

45

Glenshane Slopes Biodiversity Profile  

...BogsBlanket bog in this LCA is discontinuous and complex in its pattern of occurrence...of rough grassland; these areas produce the discontinuous pattern. Elsewhere, summits and slopes have eroded...

46

Iveagh Slopes Landscape  

...Strong horizontal field pattern on upper slopes.Sparsely settled...often emphasised by the hedgerow pattern, which radiates from the centre...is a distinctive elongated field pattern, with hedgerows running parallel to...

47

A sloping gas duct  

International Nuclear Information System (INIS)

The sloping gas duct of the THTR-300 MWe reactor connects the hot gas collection space to the steam raising unit. A sloping perforated plate is provided to even out the speed and temperature distribution at the angle. The perforated plate has circular holes, which are distributed on a regular grid. The perforated plate is made of metal or ceramic material. The free cross-section is at least 50%. (DG)

1980-01-01

48

Infiltration into pyroclastic slopes  

Science.gov (United States)

Mountainous areas of Northern Campania, Southern Italy, are characterized by steep slopes covered with pyroclastic deposits, in form of alternating layers of volcanic ashes and pumices, laying upon a pervious fractured calcareous bedrock, in some cases covered by a thin layer of impervious weathered ashes. Slope inclination is often larger than internal friction angle of such ashes (around 38°), thus equilibrium is assured by the contribution of apparent cohesion due to soil suction in unsaturated conditions. That is why, during intense and persistent rainfall events, when soil approaches saturation and consequently suction decreases, shallow landslides are frequently triggered. The physical characteristics of involved soils are such that landslides often evolve in form of debris flows, which can cause huge damages to buildings and infrastructures and, in some cases, even casualties. Understanding the role played by rainfall infiltration processes is essential to develop reliable models of slope response. To this aim, for the slope of Cervinara, where a large debris flow occurred in the past, laboratory infiltration tests and in situ monitoring are being carried out. Infiltration and evaporation tests are performed on artificial deposit reconstituted in a model slope subjected to controlled uniform rainfall, with various inclinations and bottom boundary conditions. The coupled values of soil suction and water content, observed during the experiments, have allowed defining the water retention curves experienced by the pyroclastic soil in the model slope. The performed infiltration experiments have been simulated with a mathematical model based on the integration of Richards equation with the finite volumes technique. The use of the retention curves obtained from the experiments allowed to build up reliable mathematical models of infiltration also in the case of layered slopes. Recently at the slope of Cervinara an automatic in situ monitoring station has been set up. The data of soil water content and suction collected during one year allow distinguishing different hydraulic behaviour of soil layers, and estimating soil hydraulic characteristic curves. In particular, the water retention curves derived from in situ monitoring show some differences compared to that observed in the infiltration tests on model slopes. The use of the in situ retention curves from the monitoring will allow better calibration of mathematical models of infiltration also in the case of complex geometry.

Olivares, L.; Damiano, E.; Greco, R.; Guida, A.

2012-04-01

49

Runoff from armored slopes  

International Nuclear Information System (INIS)

Models exist for calculating overland flow on hillsides but no models have been found which explicitly deal with runoff from armored slopes. Flow on armored slopes differs from overland flow, because substantial flow occurs beneath the surface of the rock layer at low runnoff, and both above and below the surface for high runoff. In addition to the lack of a suitable model, no estimates of the PMP exist for such small areas and for very short durations. This paper develops a model for calculating runoff from armored embankments. The model considers the effect of slope, drainage area and ''flow concentration'' caused by irregular grading or slumping. A rainfall-duration curve based on the PMP is presented which is suitable for very small drainage areas. The development of the runoff model and rainfall-duration curve is presented below, along with a demonstration of the model on the design of a hypothetical tailings embankment

1986-01-01

50

Slope parameters of ??-system  

International Nuclear Information System (INIS)

The slope parameters of the ??-system are calculated in the framework of the superconductor-tupe quark model. The analogous calculations are made for ?K-system. The amplitudes are obtained by using the box quark diagrams and tree diagrams with the intermediate scalar epsilon(700), Ssup(x)(975), K tilde (1350) mesons and vector rho(770), K* (892) mesons

1984-01-01

51

Western Slope Colorado  

International Nuclear Information System (INIS)

A conference on the geology and geologic resources of the Western Slope of western Colorado and eastern Utah is presented. Fourteen papers from the conference have been abstracted and indexed for the Department of Energy's Energy Data Base. These papers covered such topics as uranium resources, oil shale deposits, coal resources, oil and gas resources, and geothermal resources of the area

1981-10-08

52

Local slope stability analysis  

Science.gov (United States)

Mass movements under the influence of gravity occur as result of diverse disturbing and destabilizing processes, for example of climatic or anthropological origin. The stability of slopes is mainly determined by the geometry of the land-surface and designated slip-horizon. Further contributions are supplied by the pore water pressure, cohesion and friction. All relevant factors have to be integrated in a slope stability model, either by measurements and estimations (like phenomenological laws) or derived from physical equations. As result of stability calculations, it's suitable to introduce an expectation value, the factor-of-safety, for the slip-risk. Here, we present a model based on coupled physical equations to simulate hardly measurable phenomenons, like lateral forces and fluid flow. For the displacements of the soil-matrix we use a modified poroelasticity-equation with a Biot-coupling (Biot 1941) for the water pressure. Latter is described by a generalized Boussinesq equation for saturated-unsaturated porous media (Blendinger 1998). One aim of the calculations is to improve the knowledge about stability-distributions and their temporal variations. This requires the introduction of a local factor-of-safety which is the main difference to common stability models with global stability estimations. The reduction of immediate danger is still the emergent task of the most slope and landslide investigations, but this model is also useful with respect to understand the governing processes of landform evolution.

Hattendorf, I.; Hergarten, St.; Neugebauer, H. J.

53

The surgical treatment of children with congenital convex foot (vertical talus): evaluation of midtarsal surgical release and open reduction.  

Science.gov (United States)

In this study we evaluated the results of midtarsal release and open reduction for the treatment of children with convex congenital foot (CCF) (vertical talus) and compared them with the published results of peritalar release. Between 1977 and 2009, a total of 22 children (31 feet) underwent this procedure. In 15 children (48%) the CCF was isolated and in the remainder it was not (seven with arthrogryposis, two with spinal dysraphism, one with a polymalformative syndrome and six with an undefined neurological disorder). Pre-operatively, the mean tibiotalar angle was 150.2° (106° to 175°) and the mean calcaneal pitch angle was -19.3° (-72° to 4°). The procedure included talonavicular and calcaneocuboid joint capsulotomies, lengthening of tendons of tibialis anterior and the extensors of the toes, allowing reduction of the midtarsal joints. Lengthening of the Achilles tendon was necessary in 23 feet (74%). The mean follow-up was 11 years (2 to 21). The results, as assessed by the Adelaar score, were good in 24 feet (77.4%), fair in six (19.3%) and poor in one foot (3.3%), with no difference between those with isolated CCF and those without. The mean American Orthopaedic Foot and Ankle Society midfoot score was 89.9 (54 to 100) and 77.8 (36 to 93) for those with isolated CCF and those without, respectively. At the final follow-up, the mean tibiotalar (120°; 90 to 152) and calcaneal pitch angles (4°; -13 to 22) had improved significantly (p pes planovalgus and two in whom the deformity had been undercorrected. No child developed avascular necrosis of the talus. Midtarsal joint release and open reduction is a satisfactory procedure, which may provide better results than peritalar release. Complications include the development of pes planovalgus and persistent dorsal subluxation of the talonavicular joint. Cite this article: Bone Joint J 2014;96-B:837-44. PMID:24891587

Ramanoudjame, M; Loriaut, P; Seringe, R; Glorion, C; Wicart, P

2014-06-01

54

A solitary lesion of talus with mixed sclerotic and lytic changes: Rosai-Dorfman disease of 25 years' duration  

Energy Technology Data Exchange (ETDEWEB)

Rosai-Dorfman disease (sinus histiocytosis with massive lymphadenopathy) is an unusual form of histiocytic disorder predominantly affecting children and young adults. Bone lesions are infrequent. We describe a 63-year-old woman with a solitary lesion of the talus which was misdiagnosed for 25 years. The patient never had adenopathy or other organ involvement. The radiographic findings were a mixture of sclerotic and lytic changes, an extremely rare and unusual presentation of the disease. (orig.)

Abdelwahab, Ibrahim Fikry [Department of Radiology, New York Methodist Hospital Affiliated with Weill Medical College of Cornell University, 506 Sixth Street, NY 11215, Brooklyn (United States); Klein, Michael J. [Department of Pathology, Mount Sinai Medical Center, 1 Gustave Levy Place, NY 10029, New York (United States); Springfield, Dempsey S. [Department of Orthopedics, Mount Sinai Medical Center, 1 Gustave Levy Place, NY 10029, New York (United States); Hermann, George [Department of Radiology, Mount Sinai Medical Center, 1 Gustave Levy Place, NY 10029, New York (United States)

2004-04-01

55

Reverse Ponseti-type treatment for children with congenital vertical talus: comparison between idiopathic and teratological patients.  

Science.gov (United States)

Children with congenital vertical talus (CVT) have been treated with extensive soft-tissue releases, with a high rate of complications. Recently, reverse Ponseti-type casting followed by percutaneous reduction and fixation has been described, with excellent results in separate cohorts of children with CVT, of either idiopathic or teratological aetiology. There are currently no studies that compare the outcome in these two types. We present a prospective cohort of 13 children (21 feet) with CVT of both idiopathic and teratological aetiology, in which this technique has been used. Clinical, radiological and parent-reported outcomes were obtained at a mean follow-up of 36 months (8 to 57). Six children (nine feet) had associated neuromuscular conditions or syndromes; the condition was idiopathic in seven children (12 feet). Initial correction was achieved in all children, with significant improvement in all radiological parameters. Recurrence was seen in ten feet. Modification of the technique to include limited capsulotomy at the initial operation may reduce the risk of recurrence. The reverse Ponseti-type technique is effective in the initial correction of CVT of both idiopathic and teratological aetiology. Recurrence is a problem in both these groups, with higher rates than first reported in the original paper. However, these rates are less than those reported after open surgical release. PMID:24493197

Wright, J; Coggings, D; Maizen, C; Ramachandran, M

2014-02-01

56

Rock Slopes: Design, Excavation, Stabilization.  

Science.gov (United States)

This manual is concerned with the stability of rock slopes, with methods for assessing this stability and with techniques for improving the stability of slopes which are potentially hazardous. It is intended that it serve as both an instruction manual for...

1989-01-01

57

Interior Slopes of Copernican Craters  

Science.gov (United States)

The Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) routinely acquires high resolution (50 to 200 cm pixel scales) stereo pairs from adjacent orbits through spacecraft slews; parallax angles are typically >20°, and the local incidence angle between 40° and 65°. These observations are reduced to digital elevation models (DEM) using a combination of ISIS (USGS) and SOCET Set (BAE Systems). For this study DEMs originally sampled at 2 m scales were reduced (averaging technique) to 5 m scales to provide slopes calculated over 3x3 pixel boxes (15 m x 15 m). The upper 50% of interior walls of Copernican craters (2 to 20 km diameter) typically have average slopes of 36°, with slopes locally above 40° not uncommon (i.e. Fig 1: 2.3 km diam, 17.68°S, 144.41°E). Giordano Bruno (GB; 35.97N°, 102.86°E) is likely the youngest 20-km diameter class crater on the Moon. Its floor is dominated by impact forms (ponds and flows), and inner walls exhibit a series of coalesced flow lobes emanating from steep upper slopes. The lobes appear to be composed of dry granular material based on the observation of boulder trails superposed on many examples. The upper slopes average 36° or more, with some slopes above 40°. For much of GB, slopes exceed 30° all the way to the crater floor (especially in the SE). The high slopes imply angular grains, some level of cohesion, and/or higher angles of repose due to the Moon's relatively low gravity. Larmor Q (28.56°N, 176.33°E), another large Copernican crater, is elliptical in plan (23 x 18 km diameter), with an interior floor dominated by large slump blocks. Like GB its walls exhibit overlapping lobes (granular materials) emanating from interior wall slopes that range from 30° to 36°. Other Copernican craters exhibit similar steep slopes on interior walls: Moore F (23 km diam), Necho (30 km), and two unnamed craters (9 km,13.31°S, 257.55°E; 9 km, 15.72°, 177.39°E). Slopes of the central peaks of Tycho crater (0.1 by age) are equally steep (24° to 36°). The central peaks of Tsiolkovskiy crater (>3.0 by age) have slopes significantly shallower (20°) than younger counterparts, likely due to eons of micrometorite bombardment. High resolution (2-5 m pixel scales) LROC NAC topographic maps of impact craters are enabling characterization of slopes across a broad population of fresh and degraded craters; key information for improving numeric models of crater formation and subsequent erosion processes.

Robinson, M. S.; Burns, K.; Stelling, R.; Speyerer, E.; Mahanti, P.

2012-12-01

58

Landslide hazard zonation of slopes susceptible to rock falls and topples  

Directory of Open Access Journals (Sweden)

Full Text Available A landslide hazard zonation is a division of the land surface into areas, and the relative ranking of these areas according to degrees of actual or potential hazard from landslides on slopes. Zonation from scientific research does not generally imply legal restrictions, but can be useful to those people who are charged with the land management, by providing them with information that is indispensable for planning and regulation purposes. This paper presents a zonation of rock slopes in carbonate mountains on the boundary to the east of the valley of the Sele River (Campania, southern Apennines of Italy. The mountains are severely affected by rock falls and topples, and the related hazard is, therefore, very high; the presence of inhabited areas (the towns of Valva, Colliano and Collianello and other human infrastructures at the slope foothills make these phenomena extremely dangerous to the anthropogenic environment. The area is highly seismic, as experienced on the occasion of several moderate to strong earthquakes that have hit this sector of the Apennines. According to the zonation proposed here, the ridge of Mount Valva and Mount Marzano is subdivided into four main areas on the basis of the processes which take place in the different sectors of the mountains: the source area, the talus slope, the rockfall shadow (where scattered outlying boulders are present, and the safe area (outside of the reach of fallen blocks. The four sectors were identified through air-photo interpretation and detailed field surveys, aimed in particular at characterizing and interpreting the main rock mass joint patterns, and their relative orientation with respect to the local slope direction. Geological, morphological and structural analyses permitted one to evaluate and classify those parts of the slope that are more susceptible to detachment of rocks, and to identify the more diffuse types of failure. Due to high seismicity of the study area, particular attention was given to the evaluation of the seismic susceptibility to rock falls, by applying two methods recently proposed in literature. Results from this phase of the study were then integrated by additional information from historical research on slope movements occurred previously in the area. The landslide hazard zonation, shown on large-scale cartography, could be compared to maps depicting the distribution and typology of the anthropogenic activities, and thus constitutes a useful tool for administrators and planners, in order to evaluate the hazards related to slope movements, and the vulnerability of settlements, roads, and other man-made infrastructures.

M. Parise

2002-01-01

59

North Slope (Wahluke Slope) expedited response action cleanup plan  

International Nuclear Information System (INIS)

The purpose of this action is to mitigate any threat to public health and the environment from hazards on the North Slope and meet the expedited response action (ERA) objective of cleanup to a degree requiring no further action. The ERA may be the final remediation of the 100-I-3 Operable Unit. A No Action record of decision (ROD) may be issued after remediation completion. The US Department of Energy (DOE) currently owns or administers approximately 140 mi2 (about 90,000 acres) of land north and east of the Columbia River (referred to as the North Slope) that is part of the Hanford Site. The North Slope, also commonly known as the Wahluke Slope, was not used for plutonium production or support facilities; it was used for military air defense of the Hanford Site and vicinity. The North Slope contained seven antiaircraft gun emplacements and three Nike-Ajax missile positions. These military positions were vacated in 1960--1961 as the defense requirements at Hanford changed. They were demolished in 1974. Prior to government control in 1943, the North Slope was homesteaded. Since the initiation of this ERA in the summer of 1992, DOE signed the modified Hanford Federal Agreement and Consent Order (Tri-Party Agreement) with the Washington Department of Ecology (Ecology) and the US Environmental Protection Agency (EPA), in which a milestone was set to complete remediation activities and a draft closeout report by October 1994. Remediation activities will make the North Slope area available for future non-DOE uses. Thirty-nine sites have undergone limited characterization to determine if significant environmental hazards exist. This plan documents the results of that characterization and evaluates the potential remediation alternatives

1994-01-01

60

Western Slope of Andes, Peru  

Science.gov (United States)

Along the western flank of the Andes, 400 km SE of Lima Peru, erosion has carved the mountain slopes into long, narrow serpentine ridges. The gently-sloping sediments have been turned into a plate of worms wiggling their way downhill to the ocean. The image was acquired September 28, 2004, covers an area of 38 x 31.6 km, and is located near 14.7 degrees south latitude, 74.5 degrees west longitude. The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

2008-01-01

 
 
 
 
61

Raamatupidamine talus / Juta Uus  

Index Scriptorium Estoniae

Raamatupidamisearvestuse alustamisest; talumajapidamise eripäradest; majandustehingute dokumenteerimisest ja registrisse kandmisest; kontoplaani koostamisest; automatiseeritud andmetöötlusest; firma likvideerimisest

Uus, Juta

2005-01-01

62

Establishing proof of concept: Platelet-rich plasma and bone marrow aspirate concentrate may improve cartilage repair following surgical treatment for osteochondral lesions of the talus  

Directory of Open Access Journals (Sweden)

Full Text Available Osteochondral lesions of the talus are common injuries in the athletic patient. They present a challenging clinical problem as cartilage has a poor potential for healing. Current surgical treatments consist of reparative (microfracture or replacement (autologous osteochondral graft strategies and demonstrate good clinical outcomes at the short and medium term follow-up. Radiological findings and second-look arthroscopy however, indicate possible poor cartilage repair with evidence of fibrous infill and fissuring of the regenerative tissue following microfracture. Longer-term follow-up echoes these findings as it demonstrates a decline in clinical outcome. The nature of the cartilage repair that occurs for an osteochondral graft to become integrated with the native surround tissue is also of concern. Studies have shown evidence of poor cartilage integration, with chondrocyte death at the periphery of the graft, possibly causing cyst formation due to synovial fluid ingress. Biological adjuncts, in the form of platelet-rich plasma (PRP and bone marrow aspirate concentrate (BMAC, have been investigated with regard to their potential in improving cartilage repair in both in vitro and in vitro settings. The in vitro literature indicates that these biological adjuncts may increase chondrocyte proliferation as well as synthetic capability, while limiting the catabolic effects of an inflammatory joint environment. These findings have been extrapolated to in vitro animal models, with results showing that both PRP and BMAC improve cartilage repair. The basic science literature therefore establishes the proof of concept that biological adjuncts may improve cartilage repair when used in conjunction with reparative and replacement treatment strategies for osteochondral lesions of the talus.

Niall A Smyth

2012-01-01

63

Properties of martian slope streak populations  

Science.gov (United States)

Slope streaks are down-slope mass movements on the surface of Mars that are among the few known examples of contemporary geologic activity on Mars. Here we study slope streak activity over three decades, based on overlapping images in the Lycus Sulci region taken by the Context Camera (CTX) 2007-2010 and the Viking Orbiter Camera in 1977. The number of disappeared slope streaks is nearly equal the number of newly formed slope streaks, suggesting the streak population is balanced. The turnover time of the population is estimated to be four decades. Slope streaks fade gradually over time, with islands of persistence. We also determine the number of observable slope streaks as a function of image resolution based on images by the High Resolution Imaging Science Experiment (HiRISE) camera, and find that the number of discernible slope streaks can increase rapidly with spatial resolution.

Bergonio, Justin R.; Rottas, Kimberly M.; Schorghofer, Norbert

2013-07-01

64

Automated sliding susceptibility mapping of rock slopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a suite of extensions for ARCVIEW GIS™ (ESRI) that allows to map the spatial distribution of first-order mechanical slope-properties in hard rock terrain, e.g. for large slope areas like water reservoir slopes. Besides digital elevation data, this expert-system includes regional continuous grid-based data on geological structures that might act as potential sliding or cutoff planes for rockslides. The system allows rapid automated mapping of geometrical and kinematical slope...

2004-01-01

65

Automated sliding susceptibility mapping of rock slopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a suite of extensions for ARCVIEW GIS? (ESRI) that allows to map the spatial distribution of first-order mechanical slope-properties in hard rock terrain, e.g. for large slope areas like water reservoir slopes. Besides digital elevation data, this expert-system includes regional continuous grid-based data on geological structures that might act as potential sliding or cutoff planes for rockslides. The system allows rapid automated mapping of geometrical and kinematical slope proper...

2004-01-01

66

Slope Stability Analysis Using Numerical Method  

Directory of Open Access Journals (Sweden)

Full Text Available Stability evaluations are regularly achieved in order to measure the safe and efficient design of man-made slope (e.g., open pit mining, road cuts, etc., and/or the stability conditions of a natural slope. It has been issue of concern to numerous previous investigators. The numerical technique chosen depends on both soil specifications and its situations and the potential mode of failure. Assessment has been made for slope system with different slope for both cohesive and cohesionless soil. Two-dimensional finite element approach has been used to simulate and analysis the whole geotechnical system. This study illustrated that the factor of safety in the structure of slope case decreased while the slope was increasing for both types of soils. In addition, the displacement in the points when the section is change (in the critical zone is increasing when the slope is increasing.

Jasim M. Abbas

2014-01-01

67

Air pocket removal from downward sloping pipes:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Air-water flow is an undesired condition in water pipelines and hydropower tunnels. Water pipelines and wastewater pressure mains in particular are subject to air pocket accumulation in downward sloping reaches, such as inverted siphons or terrain slopes. Air pockets cause energy losses and an associated capacity reduction. Despite its practical relevance, many phenomena associated with airwater flow in downward sloping pipe reaches are still poorly understood. Deltares and Delft University o...

Pothof, I. W. M.; Clemens, F. H. L. R.

2012-01-01

68

Bragg reflection on a sloping beach  

Energy Technology Data Exchange (ETDEWEB)

In this study, the Bragg resonant reflection of cnoidal waves propagating over a sinusoidally varying topography lying on a uniformly sloping beach is investigated. The governing equations derived from the Boussinesq equations are numerically integrated. The effects of fast varying terms and nonlinearity in reflection coefficients are also examined. Variation of reflection coefficient for different sloping beaches is studied. It is found that reflection coefficients are not strongly dependent on slopes of beaches. (author). 8 refs., 6 figs.

Lee, Jong-In [Korea Institute of Construction Technology, Koyang (Korea); Cho, Yong-Sik [Sejong University, Seoul (Korea); Lee, Jong-Kyu [Hanyang University, Seoul (Korea)

1999-08-31

69

Slope correction for ocean radar altimetry  

Science.gov (United States)

We develop a slope correction model to improve the accuracy of mean sea surface topography models as well as marine gravity models. The correction is greatest above ocean trenches and large seamounts where the slope of the geoid exceeds 100 \\upmu rad. In extreme cases, the correction to the mean sea surface height is 40 mm and the correction to the along-track altimeter slope is 1-2 \\upmu rad which maps into a 1-2 mGal gravity error. Both corrections are easily applied using existing grids of sea surface slope from satellite altimetry.

Sandwell, David T.; Smith, Walter H. F.

2014-04-01

70

Fractal rock slope dynamics anticipating a collapse.  

Science.gov (United States)

Time series of dilatometric measurements of relative displacements on rock cracks on stable and unstable sandstone slopes were analyzed. The inherent dynamics of rock slopes lack any significant nonlinearity. However, the residuals obtained by removing meteorological influences are fat-tailed non-Gaussian fluctuations, with short-range correlations in the case of stable slopes. The fluctuations of unstable slopes exhibit self-affine dynamics of fractional Brownian motions with power-law long-range correlations and are characterized by asymptotic power-law probability distributions with decay coefficients outside the range of stable Lévy distributions. PMID:15524617

Palus, Milan; Novotná, Dagmar; Zvelebil, Jirí

2004-09-01

71

Slope factor and shallow landslide occurrence  

Science.gov (United States)

Elevations in a mature mountain are generally normally distributed and slope gradients do. Shallow landslides occur on hill slopes and involve only regolith on the slopes. The slope gradient distribution of shallow landslides (including rock falls) is also a normal distribution; similar to that of natural slopes in shape, but shifting to a higher gradient. A probability of failure curve, which is defined as the ratio of landslide cells and total cells at each interval of a factor, then shows a shape close to a cumulative normal distribution and may be fitted with a Weibull curve. The probability of failure curve commonly shows an increase of failure from gradient about 0.5 to about 1.5, and then become saturated. There are few landslides located at slope less than about 26 degrees and lost its correlation with slope when slope greater than about 56 degrees, indicating landslide type change (rock falls). This is true for the storm-induced landslides. As to the earthquake-induced landslides, there are differences to the storm-induced landslides both in distribution curve and probability of failure curve. Earthquake-induced landslides most occurred at slope gradient from 20 degrees to 54 degrees and shows a mode about 42 degrees, whereas storm-induced landslides most occurred at slope gradient from 20 degrees to 44 degrees and shows a mode about 33 degrees. There are fewer occurrences of rock falls in a storm event than that in an earthquake event. Also, earthquake-induced landslides do not show saturation at higher slope gradients in the probability of failure curve. Normally distributed topographic pattern may skew in young mountains, like those in southern Taiwan or hilly terrain in western Taiwan, and the characteristic Weibull-shaped probability of failure curve may change also. It even becomes not applicable when a very extreme storm event is involved, like typhoon Morakot event in 2009 in southern Taiwan.

Lee, Chyi-Tyi

2014-05-01

72

Calculation of three-dimensional slope stability  

Energy Technology Data Exchange (ETDEWEB)

Functions are derived for calculating slope stability in surface mines, at building sites, dams etc. The method employs parameters of a three-dimensional slope mass prone to slope slide. The sliding mass has a curved sliding surface. Two-dimensional calculation methods (according to Froehlich and to Morgenstern/Price) and also other available three-dimensional methods (according to Baligh and Azzouz as well as to Hovland) are regarded as insufficiently accurate. Parameters employed for proposed calculations are explained including geometric parameters, mass equilibrium conditions, slope failure criterion, stress distribution and safety coefficient. Calculations can be carried out on a PC. Results of a calculation example are provided. Safety coefficient and other parameters were determined for an excavator with a 55 vN/m/sup 2/ load positioned on a homogeneous 9 m high slope. A comparison of results obtained using the proposed three-dimensional method to those obtained by the Froehlich and Morgenstern/Price methods is made, showing substantially higher slope stability than that resulting from the two-dimensional calculations. The proposed method can also be applied for non-homogeneous slopes. It is pointed out that slope dimensions could be economically and technologically more favorably designed if the proposed stability calculation method were applied.

Dennhardt, M.

1986-01-01

73

Sporadic formation of slope streaks on Mars  

Science.gov (United States)

Slope streaks are a form of gravity-driven mass-movements that frequently occur on Mars today. The cause of slope streak formation remains unclear; both, dry and wet processes have been suggested. Here, we observationally constrain the time of the year during which slope streaks form. Imagery from four Mars-orbiting cameras is mined to identify locations that have been imaged repeatedly, and the overlapping images are surveyed for streak activity. A search algorithm automatically finds the locations on the surface that have been imaged most often based on a graph representation. Dark slope streaks are found to form sporadically throughout the Mars year. At one study site in the Olympus Mons Aureole, observations constrain slope streak formation to at least five distinct time intervals within a single Mars year. New slope streaks form spatially isolated or in small groups within a few kilometers of one another. The observations suggest that slope streak triggering is unrelated to season and not caused by any large regional events. Most slope streaks are caused by sporadic events of small spatial extent.

Schorghofer, Norbert; King, Christina M.

2011-11-01

74

Testing slope homogeneity in large panels  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper proposes a modified version of Swamy?s test of slope homogeneity for panel data models where the cross section dimension (N) could be large relative to the time series dimension (T). The proposed test exploits the cross section dispersion of individual slopes weighted by their relative precision.

Pesaran, Mohammad Hashem; Yamagata, Takashi

2005-01-01

75

Automated sliding susceptibility mapping of rock slopes  

Directory of Open Access Journals (Sweden)

Full Text Available We present a suite of extensions for ARCVIEW GIS™ (ESRI that allows to map the spatial distribution of first-order mechanical slope-properties in hard rock terrain, e.g. for large slope areas like water reservoir slopes. Besides digital elevation data, this expert-system includes regional continuous grid-based data on geological structures that might act as potential sliding or cutoff planes for rockslides. The system allows rapid automated mapping of geometrical and kinematical slope properties in hard rock, providing the basis for spatially distributed deterministic sliding-susceptibility evaluations on a pixel base. Changing hydrostatic slope conditions and rock mechanical parameters can be implemented and used for simple predictive static stability calculations. Application is demonstrated for a study area in the Harz Mts., Germany.

A. Günther

2004-01-01

76

Rock slopes and reservoirs - lessons learned  

International Nuclear Information System (INIS)

Lessons learned about slope stability in the course of four decades of monitoring, and in some cases stabilizing, slopes along British Columbia's hydroelectric reservoirs are discussed. The lessons are illustrated by short case histories of some of the more important slopes such as Little Chief Slide, Dutchman's Ridge, Downie Slide, Checkerboard Creek and Wahleach. Information derived from the monitoring and other investigations are compared with early interpretations of geology and slope performance. The comparison serves as an indicator of progress in slope stability determination and as a measure of the value of accumulated experience in terms of the potential consequences to safety and cost savings over the long life-span of hydroelectric projects.14 refs., 2 tabs., 15 figs

1999-05-28

77

Database on unstable rock slopes in Norway  

Science.gov (United States)

Several large rockslides have occurred in historic times in Norway causing many casualties. Most of these casualties are due to displacement waves triggered by a rock avalanche and affecting coast lines of entire lakes and fjords. The Geological Survey of Norway performs systematic mapping of unstable rock slopes in Norway and has detected up to now more than 230 unstable slopes with significant postglacial deformation. This systematic mapping aims to detect future rock avalanches before they occur. The registered unstable rock slopes are stored in a database on unstable rock slopes developed and maintained by the Geological Survey of Norway. The main aims of this database are (1) to serve as a national archive for unstable rock slopes in Norway; (2) to serve for data collection and storage during field mapping; (3) to provide decision-makers with hazard zones and other necessary information on unstable rock slopes for land-use planning and mitigation; and (4) to inform the public through an online map service. The database is organized hierarchically with a main point for each unstable rock slope to which several feature classes and tables are linked. This main point feature class includes several general attributes of the unstable rock slopes, such as site name, general and geological descriptions, executed works, recommendations, technical parameters (volume, lithology, mechanism and others), displacement rates, possible consequences, hazard and risk classification and so on. Feature classes and tables linked to the main feature class include the run-out area, the area effected by secondary effects, the hazard and risk classification, subareas and scenarios of an unstable rock slope, field observation points, displacement measurement stations, URL links for further documentation and references. The database on unstable rock slopes in Norway will be publicly consultable through the online map service on www.skrednett.no in 2014. Only publicly relevant parts of the database will be shown in the online map service (e.g. processed results of displacement measurements), while more detailed data will not (e.g. raw data of displacement measurements). Factsheets with key information on unstable rock slopes can be automatically generated and downloaded for each site, a municipality, a county or the entire country. Selected data will also be downloadable free of charge. The present database on unstable rock slopes in Norway will further evolve in the coming years as the systematic mapping conducted by the Geological Survey of Norway progresses and as available techniques and tools evolve.

Oppikofer, Thierry; Nordahl, Bo; Bunkholt, Halvor; Nicolaisen, Magnus; Hermanns, Reginald L.; Böhme, Martina; Yugsi Molina, Freddy X.

2014-05-01

78

Quadratic integer programming and the slope conjecture  

CERN Document Server

The Slope Conjecture relates a quantum knot invariant, (the degree of the colored Jones polynomial of a knot) with a classical one (boundary slopes of incompressible surfaces in the knot complement). The degree of the colored Jones polynomial can be computed by a suitable (almost tight) state sum and the solution of a corresponding quadratic integer programming problem. We illustrate this principle for a 2-parameter family of 2-fusion knots. Combined with the results of Dunfield and the first author, this confirms the Slope Conjecture for the 2-fusion knots.

Garoufalidis, Stavros

2014-01-01

79

The Logarithmic Slope in Diffractive DIS  

CERN Document Server

The logarithmic slope of diffractive structure function is a potential observable to separate the hard and soft contributions in diffraction, allowing to disentangle the QCD dynamics. In this paper we extend our previous analyzes and calculate the diffractive logarithmic slope for three current approaches in the literature: (i) the Bartels-Wusthoff model, based on perturbative QCD, (ii) the CKMT model, based on Regge theory and (iii) the Golec Biernat - Wusthoff model which assumes that the saturation phenomena is present in the HERA kinematic region. We analyze the transition region of small to large momentum transfer and verify that future experimental results on the diffractive logarithmic slope could discriminate between these approaches.

Ducati, M B G; Machado, M V T

2002-01-01

80

Simplified Visual Approach Slope Indicator (VASI).  

Science.gov (United States)

The purpose of this operational test and evaluation was to determine the value of a simplified visual approach slope indicator (VASI) system to the USAF Special Operations Force by accomplishing three test objectives: formulate and document construction c...

J. F. Yealy

1973-01-01

 
 
 
 
81

Visual Approach Slope Indicator (VASI) Improvements.  

Science.gov (United States)

The report outlines, briefly, the major work accomplished during recent years in a continuing effort to improve and update Visual Approach Slope Indicator (VASI) equipment and systems being utilized at various category airports within the United States. R...

T. H. Paprocki

1973-01-01

82

Soil Bioengineering for Upland Slope Stabilization.  

Science.gov (United States)

The objective of the study was to provide alternatives called soil bioengineering methods for slope and shallow rapid landslide stabilization along different roadside environments. Additional objectives were to educate WSDOT personnel in site selection, s...

L. Lewis S. Hagen S. Salisbury

2001-01-01

83

Context Sensitive Rock Slope Design Solutions.  

Science.gov (United States)

The Federal Highway Administration (FHWA) Federal Lands Highway Division (FLHD) evaluated the application of context sensitive solutions (CSS) for rock slope design. The application of context sensitive design in transportation is a method of developing f...

H. Hume R. Bartingale R. D. Andrew

2011-01-01

84

Unit for Grading of Rock Slopes.  

Science.gov (United States)

The design-construction bureau of the General Management of Roadways (Ministry of Transport) developed a unit for grading rock slopes. The unit is intended for conducting earth works in the conditions of mountainous locality during building and repairs of...

Khasin-Dubrovsk

1973-01-01

85

3D geodetic monitoring slope deformations  

Directory of Open Access Journals (Sweden)

Full Text Available For plenty of slope failures that can be found in Slovakia is necessary and very important their geodetic monitoring (because of their activity, reactivisations, checks. The paper gives new methodologies for these works, using 3D terrestrial survey technologies for measurements in convenient deformation networks. The design of an optimal type of deformation model for various kinds of landslides and their exact processing with an efficient testing procedure to determine the kinematics of the slope deformations are presented too.

Weiss Gabriel

1996-06-01

86

Rock Slopes from Mechanics to Decision Making  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Rock slope instabilities are discussed in the context of decision making for risk assessment and management. Hence, the state of the slope and possible failure mechanism need to be defined first. This is done with geometrical and mechanical models for which recent developments are presented. This leads with appropriate consideration of uncertainties to risk determination and to the description of tools for risk management through active and passive countermeasures, including warning systems. ...

2010-01-01

87

"Overburden stability of rock slopes in quarries"  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Many ornamental and industrila stone quarries are located along steep slopes or within particular geostructural domains in the Italian Alpine range. The stability of the overburden formations, such as detritic or cohesionless materials, blocky and altered elements or morainic formations, can be compromised by exploitation activities. In other cases there is a natural evolution of the slope, due to singular but diffused phenomena such as block falls, or due to global movements caused by gravit...

2000-01-01

88

Perceptual relevance of source spectral slope measures  

Science.gov (United States)

Researchers broadly agree that the spectral slope of the voice source is an important concomitant of voice quality. Many measures of source spectral slope have been proposed, including the relative amplitudes of the lowest few harmonics, the ratio of energy in low- versus high-frequency bands, and the average deviation from an ideal slope. It is unclear which (if any) of these measures best reflects the differences in vocal quality that result from the underlying acoustic variability. To examine this issue, a large corpus of voice samples was inverse filtered, and spectra were calculated for resulting source pulses. Different measures of spectral slope were calculated for each voice, and correlations among measures were examined. Finally, several series of synthetic stimuli were created in which only the source spectral slope varied in steps. Listeners judged the similarity of stimuli within each series. Similarity responses were evaluated with multidimensional scaling, and the resulting perceptual spaces were interpreted in terms of the different measures of source spectral slope. Measures that are highly correlated with the perceptual spaces reflect perceptually important aspects of the source signal. [Research supported by NIDCD.

Kreiman, Jody; Gerratt, Bruce R.

2001-05-01

89

Tratamento das lesões osteocondrais do talo através da técnica de microperfurações assistidas por artroscopia Treatment of osteochondral lesions of the talus by means of thearthroscopy-assisted microperforation technique  

Directory of Open Access Journals (Sweden)

Full Text Available OBJETIVO: Analisar pacientes acometidos por fratura osteocondral do talo tratados cirurgicamente através de microperfurações assistidas por artroscopia. MÉTODOS: Foi realizado um estudo retrospectivo de 24 pacientes com lesão osteocondral do talo submetidos à microperfurações assistidas por videoartroscopia do tornozelo. Todos os pacientes foram submetidos ao sistema de avaliação da American Orthopaedic Foot & Ankle Society (AOFAS no pré e pós-operatório. RESULTADOS: Foram observados 19 homens e cinco mulheres, com idade média de 35,3 anos (mínima de 17 anos e máxima de 54 anos. O tempo mínimo de seguimento foi de dois anos (máximo de 39 meses. Todos os pacientes apresentaram melhora do escore da AOFAS após o procedimento cirúrgico, com média de elevação do escore em torno de 22,5 pontos. CONCLUSÃO: A técnica de microperfurações assistidas por videoartroscopia consiste em boa opção para o tratamento das lesões osteocondrais do talo e fornece bons resultados funcionais.OBJECTIVE: To evaluate patients affected by osteochondral fractures of the talus who were treated surgically by means of arthroscopy-assisted microperforation. METHODS: A retrospective study was carried out on 24 patients with osteochondral lesions of the talus who underwent microperforation assisted by videoarthroscopy of the ankle. They were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS score system before and after the operation. RESULTS: There were 19 men and 5 women, with a mean age of 35.3 years (minimum of 17 years and maximum of 54 years. The minimum follow-up was two years (maximum of 39 months. All the patients showed an improvement in AOFAS score after surgery, with an average improvement of around 22.5 points. CONCLUSION: Videoarthroscopy-assisted microperforation is a good option for treating osteochondral lesions of the talus and provides good functional results.

Everton de Lima

2011-01-01

90

Tratamento das lesões osteocondrais do talo através da técnica de microperfurações assistidas por artroscopia / Treatment of osteochondral lesions of the talus by means of thearthroscopy-assisted microperforation technique  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Analisar pacientes acometidos por fratura osteocondral do talo tratados cirurgicamente através de microperfurações assistidas por artroscopia. MÉTODOS: Foi realizado um estudo retrospectivo de 24 pacientes com lesão osteocondral do talo submetidos à microperfurações assistidas por videoart [...] roscopia do tornozelo. Todos os pacientes foram submetidos ao sistema de avaliação da American Orthopaedic Foot & Ankle Society (AOFAS) no pré e pós-operatório. RESULTADOS: Foram observados 19 homens e cinco mulheres, com idade média de 35,3 anos (mínima de 17 anos e máxima de 54 anos). O tempo mínimo de seguimento foi de dois anos (máximo de 39 meses). Todos os pacientes apresentaram melhora do escore da AOFAS após o procedimento cirúrgico, com média de elevação do escore em torno de 22,5 pontos. CONCLUSÃO: A técnica de microperfurações assistidas por videoartroscopia consiste em boa opção para o tratamento das lesões osteocondrais do talo e fornece bons resultados funcionais. Abstract in english OBJECTIVE: To evaluate patients affected by osteochondral fractures of the talus who were treated surgically by means of arthroscopy-assisted microperforation. METHODS: A retrospective study was carried out on 24 patients with osteochondral lesions of the talus who underwent microperforation assiste [...] d by videoarthroscopy of the ankle. They were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) score system before and after the operation. RESULTS: There were 19 men and 5 women, with a mean age of 35.3 years (minimum of 17 years and maximum of 54 years). The minimum follow-up was two years (maximum of 39 months). All the patients showed an improvement in AOFAS score after surgery, with an average improvement of around 22.5 points. CONCLUSION: Videoarthroscopy-assisted microperforation is a good option for treating osteochondral lesions of the talus and provides good functional results.

Lima, Everton de; Queiroz, Felipe de; Lopes Júnior, Osmar Valadão; Spinelli, Leandro de Freitas.

91

Putting beach slope prediction into perspective  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english The storage capacity of any given tailings storage facility (TSF) is a function of the volume available for the tailings, for which the geometry of the final upper surface of the tailings is most important. One of the advantages that can be obtained from thickening tailings prior to discharge is tha [...] t the tailings can be stacked at a steeper beach angle than is obtainable with conventional low-density slurries. However, there is at present no universally accepted method available for the accurate prediction of tailings beach slopes. This paper examines the current situation with the objective of putting the quest for a method for the accurate prediction of beach slopes into perspective. The paper references published reviews of the best-known beach slope prediction methods. However, there do not appear to be any independently verified projects or published references to projects on which a Class A prediction has been validated for any of these approaches, and in those instances where projects have been implemented correlation of actual with predicted slopes has been poor - often due to differences between the properties of the tailings assumed in the design and those actually achieved in the field. The author also concludes that flume-scale testing cannot be taken as a reliable indicator of full-scale performance, and suggests that the outcome of any current predictive method should be used by experienced practitioners as only one of a range of indicators in order to suggest a range of slope angles likely to result for any given operation. Practice has shown that it is possible to manipulate beach slopes by changes to the disposal technique, such as limiting the rate of discharge per discharge point and by increasing or decreasing yield stress, but the impact of these changes cannot readily be predicted. There are also newly emerging technologies, such as the injection of a polymer into the tailings at discharge, that will enhance the dewatering of tailings and hence expedite the consolidation of the tailings, that could well facilitate the development of steeper beach slopes. The overall conclusion is that with the current state of knowledge, the accurate prediction of beach slopes is not possible. Furthermore, in view of the inherent variability of the tailings parameters from any operation, it may well be of more value to concentrate on developing an understanding of the means by which the tailings parameters may be manipulated by the operators to achieve a given beach slope than to concentrate wholly on developing a generic beach slope prediction model.

R.J., Jewell.

92

3-D slope stability analysis: A probability approach applied to the nice slope (SE France)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent geophysical and geotechnical data acquired on the Nice shelf to the east of the 1979 landslide source area, Suggest slow deformations processes which could lead to future catastrophic slope failure. According to these preliminary interpretations, it is of major interest to perform a slope stability evaluation to define the hazard and quantify the danger related to a probable instability on this slope. A probabilistic approach is proposed here using a modified version of the SAMU_3D mod...

Leynaud, Didier; Sultan, Nabil

2010-01-01

93

Finite Element analyses of soil bioengineered slopes  

Science.gov (United States)

Soil Bioengineering methods are not only effective from an economical point of view, but they are also interesting as fully ecological solutions. The presented project is aimed to define a numerical model which includes the impact of vegetation on slope stability, considering both mechanical and hydrological effects. In this project, a constitutive model has been developed that accounts for the multi-phase nature of the soil, namely the partly saturated condition and it also includes the effects of a biological component. The constitutive equation is implemented in the Finite Element (FE) software Comes-Geo with an implicit integration scheme that accounts for the collapse of the soils structure due to wetting. The mathematical formulation of the constitutive equations is introduced by means of thermodynamics and it simulates the growth of the biological system during the time. The numerical code is then applied in the analysis of an ideal rainfall induced landslide. The slope is analyzed for vegetated and non-vegetated conditions. The final results allow to quantitatively assessing the impact of vegetation on slope stability. This allows drawing conclusions and choosing whenever it is worthful to use soil bioengineering methods in slope stabilization instead of traditional approaches. The application of the FE methods show some advantages with respect to the commonly used limit equilibrium analyses, because it can account for the real coupled strain-diffusion nature of the problem. The mechanical strength of roots is in fact influenced by the stress evolution into the slope. Moreover, FE method does not need a pre-definition of any failure surface. FE method can also be used in monitoring the progressive failure of the soil bio-engineered system as it calculates the amount of displacements and strains of the model slope. The preliminary study results show that the formulated equations can be useful for analysis and evaluation of different soil bio-engineering methods of slope stabilization.

Tamagnini, Roberto; Switala, Barbara Maria; Sudan Acharya, Madhu; Wu, Wei; Graf, Frank; Auer, Michael; te Kamp, Lothar

2014-05-01

94

Slope evolution at the Calvert Cliffs, Maryland -- measuring the change from eroding bluffs to stable slopes  

Science.gov (United States)

Despite a long history of geomorphic studies, it is difficult to ascertain the time required for slopes to change from near vertical exposures to relatively stable slopes due to inadequate age control. Actively eroding coastal bluffs along the western shore of the Chesapeake Bay provide a key for understanding the centennial-scale development of stable slopes from eroding bluff faces. The Calvert Cliffs are composed of sandy silts, silty sands, and clayey silts of Miocene-age. Active wave erosion at the bluff toes encourages rapid sloughing from bluff faces and maintains slope angles of 70-80 degrees and relatively constant bluff-retreat rates. Naturally stabilized slopes are preserved as a fossil bluff line inland from a prograding cuspate foreland at Cove Point. The foreland is migrating southward at a rate of ca. 1.5 m/yr. As it moves south, it progressively protects bluffs from wave action as new beaches are deposited at their toes. Wave erosion is reinitiated at the northern end of the complex as the landform passes. An incremental record of slope change is preserved along the fossil bluff line. 14C dating of swales between beach ridges shows the complex to span 1700 years of progressive migration history. We hypothesized that slopes would change from steep, eroding faces to low-angle slopes covered with vegetation and sought to document the rate of change. Our team measured slope angles at intervals along the fossil bluff line and dated profiles by interpolating 14C ages of adjacent beach ridges. There was no progressive decrease in slope with age. All slopes along the fossil bluff line were 30-40 degrees with a mean of 35 degrees. Constancy in slope angle suggests that steep, actively eroding bluffs were quickly changed to stable slopes by landslides and slumping once they were protected. Given the accuracy of our age control, we conclude that the time required to attain a stable slope under natural processes is less than one century. This indicates that once toe erosion is ended (naturally or through engineering) slopes are reduced to 35-degrees over a period of decades and not centuries.

Herzog, Martha; Larsen, Curtis E.; McRae, Michele

2002-01-01

95

Winter chemistry of North Slope lakes  

Science.gov (United States)

Lakes are important water resources on the North Slope of Alaska. Oilfield exploration and production requires water for facility use as well as transportation. Ice road construction requires winter extraction of fresh water. Since most North Slope lakes are relatively shallow, the quantity and quality of the water remaining under the ice by the end of the winter are important environmental management issues. Currently permits are based on the presence of overwintering fish populations and their sensitivity to low oxygen. Sampling during the winter of 2004 2005 sheds light on the winter chemistry of several pumped lakes and one unpumped lake on the North Slope. Dissolved oxygen, conductivity, pH, and temperature profiles were taken along with ice thickness and water depth measurements. Water samples were extracted and analyzed for Na, Ca, K, Mg, Fe, DOC, and alkalinity in the laboratory. Lake properties, rather than pumping activities, were the best predictors of oxygen depletion, with the highest levels of dissolved oxygen maintained in the lake with the least dissolved constituents. As would be expected, specific conductance increased with depth in the lake while dissolved oxygen decreased with depth. Dissolved oxygen and specific conductance data suggested that the lakes began to refresh in May. The summarized data provides a view of North Slope lake chemistry trends, while continued studies investigate the chemical impacts of pumping North Slope lakes through continued sampling and modeling efforts.

Chambers, M. K.; White, D. M.; Lilly, M. R.; Hinzman, L. D.; Hilton, K. M.; Busey, R.

2006-12-01

96

Plasma etching of positively sloped silicon structures  

Science.gov (United States)

The fabrication of 3D high aspect ratio structures with positively sloped profiles has found extensive applications both in the front-end and in the back-end semiconductor manufacturing. Often, high etch rates are required and plasma etching processes with F-based chemistries need to be employed. However, plasma etching of silicon in F-based chemistries generally results in so-called "cusping" due to its isotropic nature. Of particular interest are the etch profiles with slope angles in the range of 50-80 ° and without "cusping" at the top portion of etched structures. For 3D packaging applications, for example, even small cusping could degrade the step-coverage of diffusion barrier layer and metal seed layer and cause void formation in subsequent metal filling processes. At Oerlikon USA Inc., a proprietary process scheme has been developed to etch deep and positively sloped silicon structures (vias, trenches, etc.) at high etch rates while eliminating cusping with precise profile control. The new process scheme employs main plasma etch steps using gas mixtures and deposition pulse steps. And the deposition pulses intermittently punctuate the main etch steps. Using standard gases, such as SF 6 and C 4F 8, sloped Si trenches with slope angle of ~60 ° are etched in both 6" and 8" wafers, at etch rates of ~7.0 (micron)m/min. Etch selectivity to photoresist mask materials exceeds 100:1. The process scheme and underlying mechanism will be presented in this work.

Lai, Shouliang; Mackenzie, Ken; Johnson, Dave; Westerman, Russ

2007-02-01

97

Sequelas a longo prazo de fracturas do corpo e colo do astrágalo / Long-term results of body and neck talus fractures  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: As fracturas do colo e corpo do astrágalo são lesões infrequentes. O objectivo deste estudo é avaliar a prevalência de sequelas a longo prazo. MÉTODOS: Foi feita uma análise retrospectiva que incluiu um total de 11 doentes sujeitos a tratamento cirúrgico por fracturas do corpo ou colo do a [...] strágalo entre Janeiro de 1997 e Dezembro de 2005. A avaliação final foi clínica (utilizando a escala AOFAS) e radiológica. RESULTADOS: O seguimento médio foi 58,5 meses. A prevalência de lesões ósseas associadas foi de 60% (6/10). O resultado AOFAS médio foi 72 [19-100] pontos. A necrose avascular e/ou artrose pós-traumática ocorreu em metade dos doentes. A qualidade da redução cirúrgica, as fracturas do corpo e a ausência de alterações degenerativas relacionaram-se com melhores resultados funcionais. As fracturas do colo, a osteonecrose e a presença de artrose pós-traumática conduziram a piores resultados. CONCLUSÃO: Há um grande potencial para sequelas tardias e compromisso funcional devido a artrose e dor crónica após esse tipo de fracturas. A redução anatómica cirúrgica é a melhor hipótese de as evitar, mas não é infalível. A taxa de necrose avascular relaciona-se com o grau de desvio inicial da fractura, mas a sua ocorrência em cada caso específico é imprevisível. Abstract in english OBJECTIVES: Talar neck and body fractures are unusual fractures. The purpose of this study is to determine the prevalence of long term results. MATERIAL AND METHODS: A retrospective analysis was carried out including 11 patients that underwent surgical treatment for body or neck talus fractures betw [...] een January 1997 and December 2005. Final follow-up examination included a clinical evaluation (AOFAS score) and standard radiographs. RESULTS: The mean follow-up time was 58.5 months. The prevalence of associated fractures was 60% (6/10). Overall AOFAS score averaged 72 [19-100]. Avascular necrosis and posttraumatic arthritis were present in half of the patients. Quality of surgical reduction, body fractures and absence of degenerative changes were correlated with better functional results. Neck fractures, osteonecrosis and posttraumatic arthritis led to inferior results. CONCLUSION: There is a great potential for long term functional impairment due to posttraumatic arthritis and chronic pain in this kind of fracture. Anatomic surgical reduction is the best chance to avoid them but it is not infallible. The avascular necrosis rate correlates with initial fracture displacement, but its occurrence in each specific case is unpredictable.

Ricardo Jorge Gomes de, Sousa; Marta Maria Teixeira de Oliveira, Massada; Manuel Alexandre Negrais Pinho Gonçalves, Pereira; Isabel Maria Gonçalves, Costa; José Fernando Souzellas da Costa e, Castro.

98

Misconceptions about incline speed for nonlinear slopes.  

Science.gov (United States)

In 3 experiments, college students provided qualitative predictions about a marble's speed along nonlinear inclines. When predicting the outcome of a race between identical marbles along differently shaped ramps, most students predicted incorrectly that the shorter path was necessarily quicker (the shorter-quicker belief). When comparing instantaneous speed at 2 points, most students predicted incorrectly that incline speed depended on the slope at that point (the slope-speed belief). A final experiment provides evidence that the slope-speed belief reflects a deeper fallacy regarding the resistance encountered while traversing inclines and lifting objects. This fallacy also predicts the prevalent belief that heavier objects fall faster than lighter objects during incline descent or free fall. PMID:12190261

Rohrer, Doug

2002-08-01

99

The logarithmic slope in diffractive DIS  

International Nuclear Information System (INIS)

The logarithmic slope of diffractive structure function is a potential observable to separate the hard and soft contributions in diffraction, allowing to disentangle the QCD dynamics at small-x region. In this paper we extend our previous analyzes and calculate the diffractive logarithmic slope for three current approaches in the literature: (i) the Bartels-Wusthoff model, based on perturbative QCD, (ii) the CKMT model, based on Regge theory and (iii) the Golec-Biernat-Wusthoff model which assumes that the saturation phenomena is present in the HERA kinematic region. We analyze the transition region of small to large momentum transfer and verify that future experimental results on the diffractive logarithmic slope could discriminate between these approaches

2002-01-28

100

The logarithmic slope in diffractive DIS  

CERN Document Server

The logarithmic slope of diffractive structure function is a potential observable to separate the hard and soft contributions in diffraction, allowing to disentangle the QCD dynamics at small-x region. In this paper we extend our previous analyzes and calculate the diffractive logarithmic slope for three current approaches in the literature: (i) the Bartels-Wusthoff model, based on perturbative QCD, (ii) the CKMT model, based on Regge theory and (iii) the Golec-Biernat-Wusthoff model which assumes that the saturation phenomena is present in the HERA kinematic region. We analyze the transition region of small to large momentum transfer and verify that future experimental results on the diffractive logarithmic slope could discriminate between these approaches.

Gay-Ducati, M B; Machado, M V T

2002-01-01

 
 
 
 
101

The logarithmic slope in diffractive DIS  

Science.gov (United States)

The logarithmic slope of diffractive structure function is a potential observable to separate the hard and soft contributions in diffraction, allowing to disentangle the QCD dynamics at small- x region. In this paper we extend our previous analyzes and calculate the diffractive logarithmic slope for three current approaches in the literature: (i) the Bartels-Wusthoff model, based on perturbative QCD, (ii) the CKMT model, based on Regge theory and (iii) the Golec-Biernat-Wusthoff model which assumes that the saturation phenomena is present in the HERA kinematic region. We analyze the transition region of small to large momentum transfer and verify that future experimental results on the diffractive logarithmic slope could discriminate between these approaches.

Gay Ducati, M. B.; Gonçalves, V. P.; Machado, M. V. T.

2002-01-01

102

Centrifuge model test of rock slope failure caused by seismic excitation. Plane failure of dip slope  

International Nuclear Information System (INIS)

Recently, it is necessary to assess quantitatively seismic safety of critical facilities against the earthquake induced rock slope failure from the viewpoint of seismic PSA. Under these circumstances, it is essential to evaluate more accurately the possibilities of rock slope failure and the potential failure boundary, which are triggered by earthquake ground motions. The purpose of this study is to analyze dynamic failure characteristics of rock slopes by centrifuge model tests for verification and improvement of the analytical methods. We conducted a centrifuge model test using a dip slope model with discontinuities limitated by Teflon sheets. The centrifugal acceleration was 50G, and the acceleration amplitude of input sin waves increased gradually at every step. The test results were compared with safety factors of the stability analysis based on the limit equilibrium concept. Resultant conclusions are mainly as follows: (1) The slope model collapsed when it was excited by the sine wave of 400gal, which was converted to real field scale, (2) Artificial discontinuities were considerably concerned in the collapse, and the type of collapse was plane failure, (3) From response acceleration records observed at the slope model, we can say that tension cracks were generated near the top of the slope model during excitation, and that might be cause of the collapse, (4) By considering generation of the tension cracks in the stability analysis, correspondence of the analytical results and the experimental results improved. From the obtained results, we need to consider progressive failure in evaluating earthquake induced rock slope failure. (author)

2008-04-01

103

Bootstrap methods for comparing independent regression slopes.  

Science.gov (United States)

In this study, we explore the effects of non-normality and heteroscedasticity when testing the hypothesis that the regression lines associated with multiple independent groups have the same slopes. The conventional approach involving the F-test and the t-test (F/t approach) is examined. In addition, we introduce two robust methods which allow simultaneous testing of regression slopes. Our results suggest that the F/t approach is extremely sensitive to violations of assumptions and tends to yield misleading conclusions. The new robust alternatives are recommended for general use. PMID:21827447

Ng, Marie; Wilcox, Rand R

2012-05-01

104

Radial slope measurement of dynamic transparent samples  

International Nuclear Information System (INIS)

An interferometric method to measure the radial slope of dynamic transparent samples is presented. We have implemented a simultaneous phase shifting Mach–Zehnder radial-shear interferometer (SPS-MZRI) using a phase grating to replicate the interference patterns and phase shifts modulated by polarization; the interferometer is capable of processing the optical phase data through the acquisition of n-interferograms captured simultaneously. The SPS-MZRI is capable of obtaining the radial phase derivative and associating it with its corresponding radial slope. The experimental results for static and dynamic samples are presented in this work, as well as the experimental evidence for the generation of spiral patterns. (paper)

2012-04-01

105

Terrestrial laser scanning of rock slope instabilities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This manuscript presents a review on the application of a remote sensing technique (terrestrial laser scanning, TLS) to a well-known topic (rock slope characterization and monitoring). Although the number of publications on the use of TLS in rock slope studies has rapidly increased in the last 5-10years, little effort has been made to review the key developments, establish a code of best practice and unify future research approaches. The acquisition of dense 3D terrain information with high a...

2014-01-01

106

Development of Probabilistic Safety Assessment Considering Slope Collapse by Earthquake  

International Nuclear Information System (INIS)

In Japan, a part of nuclear power plants is surrounded by the land slope. In such a nuclear power plant, it is necessary to evaluate the stability of the slope under the deterministic seismic condition, and to ascertain that the plant is kept in a safe condition even if collapse of the slope might occur due to earthquakes. A probabilistic safety assessment methodology considering the slope collapse (Slope PSA) has been developed as a part of seismic PSA at Japan Nuclear Energy Safety Organization (JNES). This method consists of slope collapse hazard evaluation, fragility evaluation (evaluation of secondary influences on nuclear facilities) and system reliability analysis. In the slope collapse hazard evaluation, probabilities of slope stability, failure modes, collapse behavior, rock reach area and shock force to nuclear facility are analyzed and calculated. This report describes the slope collapse hazard evaluation procedure and sample calculations for a model slope, and also results of parametric studies for the rock block behavior analysis. (authors)

2007-11-14

107

Continental Shelf Waves over a Continental Slope.  

Science.gov (United States)

A numerical study is made of the effect of a continental slope and shelf of finite width on trapped shelf and edgewaves. A comparison is made between a numerical solution for a continental shelf of finite width and its simplified analytic solution. It is ...

H. D. Sturr

1969-01-01

108

Universal Regge slope ?' from QCD gluon propagator  

International Nuclear Information System (INIS)

An effective gluon propagator is estimated in the presence of a fluctuating color magnetic field in vacuum. Using the dual honeycomb diagram tlhe universal slope is estimated to yield ?sub(p) = 0.34 GeV when corrected by instanton, for ?' = 0.88 GeV-2. (Auth.)

1980-01-01

109

Wave Runup on Smooth and Rock Slopes.  

Science.gov (United States)

Knowledge on wave runup levels is important for a proper design of the crest height of coastal structures. An overall view of the literature supports the theory that smooth slopes cause the highest possible runup levels. Therefore, various runup data on g...

J. W. van der Meer C. J. M. Stam

1991-01-01

110

Toppling on Rock Slopes: An Overview.  

Science.gov (United States)

Several modes of rock slope failure have been fairly well defined and classified. Of particular interest are plane, wedge, and circular failure modes, each of which has a well-defined geometry and failure mechanism. As a result, a variety of equilibrium m...

R. L. McNearny

1987-01-01

111

Analysis of Bolt Reinforcement in Rock Slopes.  

Science.gov (United States)

The modeling of bolt reinforcement in rock slopes is discussed. The shear strength of rough-surfaced rock joints is related to the amount of dilation possible in the joint. By bolting the joint and restraining dilation, shear strength is greatly increased...

F. E. Heuze

1981-01-01

112

Ranking Slope Stability in Frozen Terrain  

Science.gov (United States)

Motivated by the need to assess the risk of permafrost thaw to infrastructure, such as roads, bridges, and pipelines, a landscape-scale approach was developed to rank the risk of slope failures and thermokarst development in areas of seasonally frozen soils underlain by permafrost. The approach has two parts: (i) identifying locations where permafrost thaw is likely to occur under future climates, and (ii) identifying areas where thaw would have consequences with respect to a disturbance. The developed screening tool uses (i) land classification maps developed from remotely sensed data and (ii) a thermohydrologic hazard risk assessment to identify areas susceptible to slope instability under current and future climate states. The screening tool combines a numerical ground thawing and freezing dynamics model for calculating the thickness of the active layer and depth of permafrost with a simple slope stability model that is based upon the Level I Stability Analysis (LISA) approach of Harrell et al. (1992). Instead of using the numerical models directly within probabilistic sampling, a response function for the factor of safety in slope stability is developed from numerical simulations that systematically vary input parameters across their range of applicability. The response function is used within Monte Carlo sampling for each grid cell in a landscape model, with a probability distribution for each input parameter assigned to each grid cell based on (i) classes defined for each grid cell; (ii) a digital elevation model; (iii) empirical, mathematical, and numerical interpretive models; and (iv) probabilistic descriptions of the parameters in the interpretive models. For example, the root cohesion distribution is defined by vegetation class, with vegetation spread across the landscape using Landsat-derived vegetation classification maps. The probability of slope failure is the fraction of parameter realizations that result in a factor of safety less than 1. Ranking may be performed based on the expected factor of safety, the probability of slope failure, or the maximum soil thickness compatible with slope stability. Harrell, C., D. Hall, S. Miller, and P. Swetick. Level I Stability Analysis (LISA) Documentation for Version 2.0. General Technical Report INT-285, U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Moscow, ID. 1992.

Stothoff, S.; Dinwiddie, C. L.; Walter, G. R.; Necsoiu, M.

2011-12-01

113

Evaluation of Slope Assessment Systems for Predicting Landslides of Cut Slopes in Granitic and Meta-sediment Formations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In Malaysia, slope assessment systems (SAS) are widely used in assessing the instability of slope or the probability of occurrence and the likely severity of landslides. These SAS can be derived based on either one particular approach or combination of several approaches of landslide assessments and prediction. This study overviews four slope assessment systems (SAS) developed in Malaysia for predicting landslide at a large-scale assessments. They are the Slope Maintenance System (SMS), Slope...

2006-01-01

114

Automatic delineation of geomorphological slope units  

Science.gov (United States)

Slope units are portions of land surface, defined by the general requirement of maximizing homogeneity within a single unit and heterogeneity between different units, but whose formal characterization and practical delineation has been done in different ways. This is often justified by the statement that the slope unit partitioning of a territory can be used to describe a variety of landforms and processes, and for the assessment of natural hazards. As a result, they need to be tailored according to the specific model in use. This may result in an ambiguous definition of such objects, while an objective definition is highly desirable, which would also allow their reproducibility. We have developed a publicly accessible Web Processing Service (WPS) with the aim of incrementally achieve a satisfactory definition of slope unit. The service allows any user to connect to a CNR-IRPI (Perugia) server, upload his own Digital Elevation Model (DEM) and optional additional data, specify parameters constraining the size and aspect of slope units, and quickly obtain the result in a layer in vector format. The calculation is performed using a parallel algorithm, resulting in a processing time short enough to allow the user to tune the input parameters, repeating the process for a sufficient number of times in order to obtain a satisfactory result. We use quantitative criteria to define and draw the slope units, depending on the input parameters. The algorithm starts from a hydrologically consistent partition of the study area into half-basins with a large number of contributing DEM cells. Each of the half-basins is then checked against a few requirements: maximum area required by the user and maximum standard deviation of the aspect on two orthogonal directions. Those specific half-basin that do not meet the requirements are partitioned further, requiring a lower number of contributing cells. The process is iterated until no half-basin exceeds the user-specified thresholds. Our aim is to encourage users to test the algorithm on a large number of areas with different topographies so that new, meaningful requirements on the individual half-basins can be defined and included in our process, in order to achieve a robust and reproducible algorithm embodying a vast class of desiderata in the slope unit definition. This will eventually constitute a performing and customizable tool for the investigation of a variety of geomorphological phenomena.

Alvioli, Massimiliano; Marchesini, Ivan; Fiorucci, Federica; Ardizzone, Francesca; Rossi, Mauro; Reichenbach, Paola; Guzzetti, Fausto

2014-05-01

115

The effect of a weak layer in slope stability  

Energy Technology Data Exchange (ETDEWEB)

In designing very large excavated slopes which are becoming increasingly common in both mining and civil engineering projects, the most important decision of the engineer is the selection of a slope angle. The purpose of the geotechnical study of the slope is to ensure reasonable stability of the slope in the most economical way. Because the rock mass composing each slope is unique, there are no standard solutions for slope stability analysis. A practical solution is formulated from the basic geologic data, engineering properties of the rock, geometry of the slope, and ground water observations. Stability analysis consists of analyzing the forces causing and resisting slope failure. There are several methods of slope stability analysis. The limit equilibrium method evaluates the overall stability of the sliding mass just on the verge of slip, using some or all of the three equations of static equilibrium of a plane problem.

Vakili, J.

1982-09-01

116

Wildlife response on the Alaska North Slope  

International Nuclear Information System (INIS)

Recognizing the need for a comprehensive plan to deal with potentially oiled wildlife on the Alaskan North Slope, a multifaceted wildlife protection strategy was developed and implemented during 1991. The strategy incorporated all aspects of wildlife response including protection of critical habitat, hazing, capture and stabilization, long term rehabilitation, and release. The primary wildlife response strategy emphasizes controlling of the release and spreading of spilled oil at the source to prevent or reduce contamination of potentially affected species and/or their habitat. A secondary response strategy concentrates on keeping potentially affected wildlife away from an oiled area through the use of deterrent techniques. Tertiary response involves the capture and treatment of oiled wildlife. Implementation of the strategy included the development of specialized training, the procurement of equipment, and the construction of a bird stabilization center. The result of this initiative is a comprehensive wildlife response capability on the Alaskan North Slope. 1 ref., 5 figs., 3 tabs

1992-06-10

117

The Salpeter Slope of the IMF Explained  

Science.gov (United States)

If we accept a paradigm that star formation is a self-similar, hierarchical process, then the Salpeter slope of the IMF for high-mass stars can be simply and elegantly explained as follows. If the intrinsic IMF at the smallest scales follows a simple -2 power-law slope, then the steepening to the -2.35 Salpeter value results when the most massive stars cannot form in the lowest-mass clumps of a cluster. It is stressed that this steepening must occur if clusters form hierarchically from clumps, and the lowest-mass clumps can form stars. This model is consistent with a variety of observations as well as theoretical simulations.

Oey, M. Sally

118

Slope variations on the surface of Phobos  

Science.gov (United States)

It has been suggested that slope fluctuations on the scale of pixel dimensions could be determined by statistical photoclinometry. A closer study of the surface of Phobos reveals variations in the scattering properties of single particles and microstructures formed by the particles. In the present context, the photoclinometric method of brightness moments is extended to account for these variations by allowing statistical fluctuations in the phase function of the assumed Lommel-Seeliger scattering law. The mean slope on the investigated regions of Phobos has been found to vary from about 12 deg on a 61 m scale to about 7 deg on a 216 - 272 m scale. On the same scales, a value of the order of 2 percent has been obtained for the standard deviation of the scattering phase function. Hints of a fractal-like scale-invariance have been noticed in the covariance function of brightness.

Muinonen, Karri; Lumme, Kari; Irvine, William M.

1991-01-01

119

Ocean processes at the Antarctic continental slope.  

Science.gov (United States)

The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean-atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce water mass properties of the region. Dynamics at the continental slope are key for correctly modelling climate, yet their small spatial scale presents challenges both for ocean modelling and for observational studies. Cross-slope exchange processes are also vital for the flux of nutrients such as iron from the continental shelf into the mixed layer of the Southern Ocean. An iron-cycling model embedded in an eddy-permitting ocean model reveals the importance of sedimentary iron in fertilizing parts of the Southern Ocean. Ocean gliders play a key role in improving our ability to observe and understand these small-scale processes at the continental shelf break. The Gliders: Excellent New Tools for Observing the Ocean (GENTOO) project deployed three Seagliders for up to two months in early 2012 to sample the water to the east of the Antarctic Peninsula in unprecedented temporal and spatial detail. The glider data resolve small-scale exchange processes across the shelf-break front (the Antarctic Slope Front) and the front's biogeochemical signature. GENTOO demonstrated the capability of ocean gliders to play a key role in a future multi-disciplinary Southern Ocean observing system. PMID:24891389

Heywood, Karen J; Schmidtko, Sunke; Heuzé, Céline; Kaiser, Jan; Jickells, Timothy D; Queste, Bastien Y; Stevens, David P; Wadley, Martin; Thompson, Andrew F; Fielding, Sophie; Guihen, Damien; Creed, Elizabeth; Ridley, Jeff K; Smith, Walker

2014-07-13

120

Slope stability under rapid drawdown conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The rapid drawdown condition arises when submerged slopes experience rapid reduction of the external water level. Classical analysis procedures are grouped in two classes: the “stress-based” undrained approach, recommended for impervious materials and the flow approach, which is specified for rigid pervious materials (typically a granular soil). Field conditions often depart significantly from these simplified cases and involve materials of different permeability and compressibility ar...

Alonso Pe?rez Agreda, Eduardo; Pinyol Puigmarti?, Nu?ria Merce?

2009-01-01

 
 
 
 
121

Viscous liquid flow on Martian dune slopes  

CERN Document Server

The observed temporary dark streaks on some dune slopes on Mars may be due to thin sheets of water (or some other liquid) trickling downhill. This note corrects conceptual errors in a previous paper (M\\"{o}hlmann and Kereszturi 2010, Icarus 207, 654-658) which affect the velocity profile of such flows, and produce over-estimates of their depths and mass fluxes by factors of almost two.

Dobrovolskis, Anthony R

2014-01-01

122

Motion of rock masses on slope  

Directory of Open Access Journals (Sweden)

Full Text Available This paper shows the different ways of how rock masses (stones, rocks, and blocks move along slopes and for each different way of motion (free fall, bouncing, rolling, sliding, slowing down, lubrication, fluidizationadequatedynamicequationsaregiven.Knowingthe kinematics and dynamics of travelling rock masses is necessary for mathematical modeling of motion and by this an assessment of maximal possible rockfall runout distances as an example of a sudden and hazardeous natural phenomenon, threatening man and his property, especially in the natural environment.

Urška Petje

2006-12-01

123

Motion of rock masses on slope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper shows the different ways of how rock masses (stones, rocks, and blocks) move along slopes and for each different way of motion (free fall, bouncing, rolling, sliding, slowing down, lubrication, fluidization)adequatedynamicequationsaregiven.Knowingthe kinematics and dynamics of travelling rock masses is necessary for mathematical modeling of motion and by this an assessment of maximal possible rockfall runout distances as an example of a sudden and hazardeous natural phenomenon, thr...

2006-01-01

124

Slope stability monitoring from microseismic field using polarization methodology  

Directory of Open Access Journals (Sweden)

Full Text Available Numerical simulation of seismoacoustic emission (SAE associated with fracturing in zones of shear stress concentration shows that SAE signals are polarized along the stress direction. The proposed polarization methodology for monitoring of slope stability makes use of three-component recording of the microseismic field on a slope in order to pick the signals of slope processes by filtering and polarization analysis. Slope activity is indicated by rather strong roughly horizontal polarization of the respective portion of the field in the direction of slope dip. The methodology was tested in microseismic observations on a landslide slope in the Northern Tien-Shan (Kyrgyzstan.

Yu. I. Kolesnikov

2003-01-01

125

Geosynthetic clay liners - slope stability field study  

Energy Technology Data Exchange (ETDEWEB)

A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project.

Carson, D.A. [Environmental Protection Agency, Cincinnati, OH (United States); Daniel, D.E. [Univ. of Illinois, Urbana, IL (United States); Koerner, R.M. [Geosynthetic Research Institute, Philadelphia, PA (United States); Bonaparte, R. [GeoSyntec Consultants, Atlanta, GA (United States)

1997-12-31

126

Similarity Scaling Over a Steep Alpine Slope  

Science.gov (United States)

In this study, we investigate the validity of similarity scaling over a steep mountain slope (30-41^circ ). The results are based on eddy-covariance data collected during the Slope Experiment near La Fouly (SELF-2010); a field campaign conducted in a narrow valley of the Swiss Alps during summer 2010. The turbulent fluxes of heat and momentum are found to vary significantly with height in the first few metres above the inclined surface. These variations exceed by an order of magnitude the well-accepted maximum 10 % required for the applicability of Monin-Obukhov similarity theory in the surface layer. This could be due to a surface layer that is too thin to be detected or to the presence of advective fluxes. It is shown that local scaling can be a useful tool in these cases when surface-layer theory breaks down. Under convective conditions and after removing the effects of self-correlation, the normalized standard deviations of slope-normal wind velocity, temperature and humidity scale relatively well with z/\\varLambda , where z is the measurement height and \\varLambda (z) the local Obukhov length. However, the horizontal velocity fluctuations are not correlated with z/\\varLambda under all stability regimes. The non-dimensional gradients of wind velocity and temperature are also investigated. For those, the local scaling appears inappropriate, particularly at night when shallow drainage flows prevail and lead to negative wind-speed gradients close to the surface.

Nadeau, Daniel F.; Pardyjak, Eric R.; Higgins, Chad W.; Parlange, Marc B.

2013-06-01

127

Toric Slope Stability and Partial Bergman Kernels  

CERN Multimedia

Let $(L, h)\\to (X, \\omega)$ denote a polarized toric K\\"ahler manifold. Fix a toric submanifold $Y$ and denote by $\\hat{\\rho}_{lk}:X\\to \\mathbb{R}$ the partial density function corresponding to the partial Bergman kernel projecting smooth sections of $L^k$ onto holomorphic sections of $L^k$ that vanish to order at least $lk$ along $Y$, for fixed $l>0$ such that $lk\\in \\mathbb{N}$. We prove the existence of a distributional expansion of $\\hat{\\rho}_{lk}$ up to order $k^{n-2}$ as $k\\to \\infty$, including the identification of the coefficient of $k^{n-1}$ as a distribution on $X$. This expansion is used to give a direct proof that if $\\omega$ has constant scalar curvature, then $(X, L)$ must be slope semi-stable with respect to $Y$. More generally, it is shown that under the same hypotheses, $(X,L)$ must be slope semi-stable with respect to any closed toric subscheme $Z$ of $X$. In many cases, moreover, $(X,L)$ will be slope stable with respect to $Z$.

Pokorny, Florian T

2011-01-01

128

On Front Slope Stability of Berm Breakwaters  

DEFF Research Database (Denmark)

The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison with the reshaping of a large Norwegian breakwater exposed to the North Sea waves. As a motivation for applying the Van der Meer formula a discussion of design parameters related to berm breakwater stability formulae is given. Comparisons of front erosion predicted by the use of the Van der Meer formula with model test results including tests presented in Sigurdarson and Van der Meer (2011) are discussed. A proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope, relative berm height, relative berm width, method of armour stone placement, and hydraulic parameters. The formulae should cover the structure range from statically stable berm breakwaters to conventional double layer armoured breakwaters.

Burcharth, Hans F.

2013-01-01

129

Geosynthetic clay liners - slope stability field study  

International Nuclear Information System (INIS)

A field research project was developed to examine the internal shear performance of geosynthetic clay liners (GCLs). Several combinations of cross sections were assembled using GCL materials that were available at the time of project initiation. The cross sections utilized were intended to simulate landfill cover applications. Thirteen (13) resulting test plots were constructed on two different slope angles, and each plot is instrumented for physical displacement and soil moisture characteristics. Test plots were constructed in a manner that dictated the shear plane in the clay portion of the GCL product. The project purpose is to assess field performance and to verify design parameters associated with the application of GCLs in waste containment applications. Interim research data shows that test slopes on 2H:1V show global deformation, but little internal shear evidence, and the 3H:1V slopes show little deformation at approximately 650 days. The research is ongoing, and this paper presents the most recent information available from the project

1997-02-09

130

Stability of nuclear crater slopes in rock  

International Nuclear Information System (INIS)

The United States Army Engineer Nuclear Cratering Group was established in 1962 to participate with the Atomic Energy Commission in a joint research and development program to develop nuclear engineering and construction technology. A major part of this research effort has been devoted to studies of the engineering properties of craters. The program to date has included field investigations of crater properties in various media over a broad range of chemical and nuclear explosive yields, studies of man-made and natural slopes, and studies directed toward the development of analytical and empirical methods of crater stability analysis. From this background, a general understanding has been developed of the effects of a cratering explosion on the surrounding medium and of physical nature of the various crater zones which are produced. The stability of nuclear crater slopes has been a subject of prime interest in the feasibility study being conducted for an Atlantic-Pacific sea-level canal. Based on experimental evidence assembled to date, nuclear crater slopes in dry dock and dry alluvium have an initially stable configuration. There have been five nuclear craters produced to date with yields of 0.4 kt or more on which observations are based and the initial configurations of these craters have remained stable for over seven years. The medium, yield, crater dimensions, and date of event for these craters are summarized. It is interesting to note that the Sedan Crater has been subjected to strong seismic motions from nearby detonations without adverse effects

1970-05-01

131

Alterações radiográficas do tálus no pé torto congênito após liberação cirúrgica pela técnica de McKay / Radiographic changes of the talus in congenital clubfoot after surgical release using the mckay procedure  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Analisar as alterações morfológicas do tálus após o tratamento cirúrgico do pé torto congênito pela técnica de McKay. MÉTODOS: Foram analisadas, retrospectivamente, radiografias em perfil com carga dos pés de 14 pacientes com pé torto congênito unilateral submetidos ao tratamento pela técn [...] ica de McKay por dupla incisão. Todos os pacientes foram operados pelo mesmo cirurgião, com média de 6,53 anos entre a cirurgia e a radiografia. Comparamos as características do tálus dos pés operados com os parâmetros radiográficos dos pés contralaterais. Avaliamos a presença de deformidade do dômus e da cabeça do tálus (avaliação da esfericidade), a altura e o comprimento do tálus, a presença e grau de subluxação do navicular, a alteração do ângulo de Gissane e o padrão do trabeculado ósseo. RESULTADOS: Alterações da cabeça do tálus ocorreram em 92,8% dos casos; do dômus, em 92,8%; e do trabeculado, em 100%. A relação entre o comprimento do tálus do pé operado sobre o contralateral variou de 0,61 a 0,88 (média de 0,79; DP = 0,09), e da altura de 0,57 a 0,98 (média de 0,82; DP = 0,12). O ângulo de Gissane aumentou em todos os pés operados, e todos apresentaram subluxação do navicular, com índice variando de 6,43 a 59,75% (média de 26,34%; DP = 16,66%). CONCLUSÕES: Alterações talares ocorreram em 100% dos pés tratados pela técnica de McKay. Estabelecer parâmetros radiográficos para descrever e quantificar essas deformidades mostrou-se viável através de técnicas simples e de fácil execução. Abstract in english OBJECTIVE: To analyze the morphologic changes of the talus after surgical treatment of congenital clubfoot using the McKay procedure. METHODS: We retrospectively analyzed lateral standing radiographs of the feet in 14 patients with unilateral clubfoot treated by the McKay procedure. All patients wer [...] e operated on by the same surgeon, with an average of 6.53 years between surgery and the radiograph. We compared the characteristics of the talus between the operated foot and the contralateral foot. We evaluated the deformity of the domus and the head of the talus (sphericity evaluation), the talar length and height, the presence and percentage of navicular subluxation, changes in the Gissane angle, and the trabecular pattern of the bone. RESULTS: Deformities of the head of the talus were observed in 92.8% of the patients; of the domus in 92.8%; and of the trabecular pattern in 100%. The ratio between the talar lengths of the operated foot and the contralateral foot ranged from 0.61 to 0.88 (Mean 0.79, SD = 0.09), while the height ratio ranged from 0.57 to 0.98 (Mean 0.82, SD = 0.12). The Gissane angle was increased in all of the operated feet, which also showed some degree of navicular subluxation, ranging from 6.43 to 59.75% (Mean 26.34%, SD = 16.66%). CONCLUSIONS: Abnormal talar findings were observed in 100% of the feet treated using the McKay procedure. The establishment of radiographic parameters to describe and quantify these deformities was feasible through simple and easy techniques.

José Antonio, Pinto; Andréa Canizares, Hernandes; Thais de Paula, Buchaim; Francesco Camara, Blumetti; Carla, Chertman; Patrícia Corey, Yamane; Artur da Rocha Corrêa, Fernandes.

132

Prediction of Erosion on Cut or Fill Slopes. Executive Summary,  

Science.gov (United States)

Previous research relative to the Universal Soil Loss Equation (USLE) and rainfall simulators are reviewed. A programmable rainfall simulator was modified and successfully operated on highway slopes with slope steepness from 9% to 50% at Putnamville and E...

J. C. Fan

1988-01-01

133

Prediction of Erosion on Cut or Fill Slopes. Final Report,  

Science.gov (United States)

Previous research relative to the Universal Soil Loss Equation (USLE) and rainfall simulators are reviewed. A programmable rainfall simulator was modified and successfully operated on highway slopes with slope steepness from 9% to 50% at Putnamville and E...

J. C. Fan

1988-01-01

134

Evaluation of Slope Assessment Systems for Predicting Landslides of Cut Slopes in Granitic and Meta-sediment Formations  

Directory of Open Access Journals (Sweden)

Full Text Available In Malaysia, slope assessment systems (SAS are widely used in assessing the instability of slope or the probability of occurrence and the likely severity of landslides. These SAS can be derived based on either one particular approach or combination of several approaches of landslide assessments and prediction. This study overviews four slope assessment systems (SAS developed in Malaysia for predicting landslide at a large-scale assessments. They are the Slope Maintenance System (SMS, Slope Priority Ranking System (SPRS, Slope Information Management System (SIMS and the Slope Management and Risk Tracking System (SMART. An attempt is made to evaluate the accuracy of the SAS in predicting landslides based on slope inventory data from 139 cut slopes in granitic formation and 47 cut slopes in meta-sediment formation, which are the two most common rock/soil formations found in Malaysia. Based on this study, it was found that none of existing SAS is satisfactory in predicting landslides of cut slopes in granitic formation, for various reasons such as the use of hazard score developed from another country, insufficient data base, oversimplified approach and use of data base derived from different rock/soil formations. However for the case of cut slope in meta-sediment, the Slope Management and Risk Tracking System (SMART was found to be satisfactory with 90% prediction accuracy. The current database of SMART is largely based on meta-sediment formation.

Suhaimi Jamaludin

2006-01-01

135

The Role of Slope Geometry on Flowslide Occurrence  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The paper reports a study aimed to the prediction of susceptibility to flowslide of granular soil slopes as a consequence of the in situ state of stress. In particular, the slope geometry has been investigated as a factor influencing the initial state of stress. For this purpose the results of numerical models, performed by a finite different approach (FLAC), allowed the complete definition, in any point of the slope, of the stress conditions by changing slope height and inclination. By relat...

Chiara Deangeli

2007-01-01

136

Correlation between slope stability and methods of spoil bank formation  

Energy Technology Data Exchange (ETDEWEB)

The problems of slope stability are discussed arising as a consequence of failures made during excavation and dumping of overburden. Recommendations are made in regard to slope angles and bench height during dumping of clayey and sandy overburden when applying various technologies. Waste dumping technologies, practical values for slope angles, bench heights and spoil bank subsidence are listed in six tables. 4 references.

Obradovic, R.

1985-10-01

137

Solar dazzle reflected from sloping glazed facades  

Energy Technology Data Exchange (ETDEWEB)

Glare or dazzle can occur when sunlight is reflected from a glazed facade. For vertical facades this problem usually occurs only when the sun is low in the sky; but some types of modern design incorporate sloping glazed facades which can, under certain circumstances, reflect unwanted high altitude sunlight into the eyes of motorists, pedestrians and people in nearby buildings. A new method which can be used at the design stage to calculate whether such solar dazzle will be reflected from a proposed building facade is discussed for the benefit of architects, consulting engineers, planning consultants and planners.

Littlefair, P.J.

1987-04-01

138

Estimating Manning's n for steep slopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hydrological and soil erosion models require calculations of flow velocity, for which either the Darcy-Weisbach or the Manning equation is generally used. A series of field experiments was carried out in a small catchment on the Chinese Loess Plateau to obtain reliable values of Manning's n. The soils are typically erodible loess soils. The experiments were conducted for a range of land uses as well as for different slope angles (6¿64%). Measurements were performed on a 2.5×0.4 m plot, on w...

Hessel, R.; Jetten, V. G.; Zhang, G. H.

2003-01-01

139

Boundary slopes and the logarithmic limit set  

CERN Multimedia

The A-polynomial of a manifold whose boundary consists of a single torus is generalised to an eigenvalue variety of a manifold whose boundary consists of a finite number of tori, and the set of strongly detected boundary curves is determined by Bergman's logarithmic limit set, which describes the exponential behaviour of the eigenvalue variety at infinity. This enables one to read off the detected boundary curves of a multi-cusped manifold in a similar way to the 1-cusped case, where the slopes are encoded in the Newton polygon of the A-polynomial.

Tillmann, S

2003-01-01

140

Outerplanar graph drawings with few slopes  

CERN Document Server

We consider straight-line outerplanar drawings of outerplanar graphs in which the segments representing edges are parallel to a small number of directions. We prove that Delta-1 directions suffice for every outerplanar graph with maximum degree Delta>=4. This improves the previous bound of O(Delta^5), which was shown for planar partial 3-trees, a superclass of outerplanar graphs. The bound is tight: for every Delta>=4 there is an outerplanar graph of maximum degree Delta which requires at least Delta-1 distinct edge slopes for an outerplanar straight-line drawing.

Knauer, Kolja; Walczak, Bartosz

2012-01-01

 
 
 
 
141

Western Ross Sea continental slope gravity currents  

Science.gov (United States)

Antarctic Bottom Water of the world ocean is derived from dense Shelf Water that is carried downslope by gravity currents at specific sites along the Antarctic margins. Data gathered by the AnSlope and CLIMA programs reveal the presence of energetic gravity currents that are formed over the western continental slope of the Ross Sea when High Salinity Shelf Water exits the shelf through Drygalski Trough. Joides Trough, immediately to the east, offers an additional escape route for less saline Shelf Water, while the Glomar Challenger Trough still farther east is a major pathway for export of the once supercooled low-salinity Ice Shelf Water that forms under the Ross Ice Shelf. The Drygalski Trough gravity currents increase in thickness from ˜100 to ˜400 m on proceeding downslope from ˜600 m (the shelf break) to 1200 m (upper slope) sea floor depth, while turning sharply to the west in response to the Coriolis force during their descent. The mean current pathway trends ˜35° downslope from isobaths. Benthic-layer current and thickness are correlated with the bottom water salinity, which exerts the primary control over the benthic-layer density. A 1-year time series of bottom-water current and hydrographic properties obtained on the slope near the 1000 m isobath indicates episodic pulses of Shelf Water export through Drygalski Trough. These cold (34.75) pulses correlate with strong downslope bottom flow. Extreme examples occurred during austral summer/fall 2003, comprising concentrated High Salinity Shelf Water (-1.9 °C; 34.79) and approaching 1.5 m s -1 at descent angles as large as ˜60° relative to the isobaths. Such events were most common during November-May, consistent with a northward shift in position of the dense Shelf Water during austral summer. The coldest, saltiest bottom water was measured from mid-April to mid-May 2003. The summer/fall export of High Salinity Shelf Water observed in 2004 was less than that seen in 2003. This difference, if real, may reflect the influence of the large iceberg C-19 over Drygalski Trough until its departure in mid-May 2003, when there was a marked decrease in the coldest, saltiest gravity current adjacent to Drygalski Trough. Northward transport of cold, saline, recently ventilated Antarctic Bottom Water observed in March 2004 off Cape Adare was ˜1.7 Sv, including ˜0.4 Sv of High Salinity Shelf Water.

Gordon, Arnold L.; Orsi, Alejandro H.; Muench, Robin; Huber, Bruce A.; Zambianchi, Enrico; Visbeck, Martin

2009-06-01

142

Surface energy fluxes on four slope sites during FIFE 1988  

Science.gov (United States)

Four slopes (facing north, south, east, and west) in the Konza Prairie Research Natural Area were selected to study the effect of topography on surface energy balance and other micrometeorological variables. Energy fluxes, air temperature, and vapor pressure were measured on the slopes throughout the 1988 growing season. Net radiation was highest on the south facing slope and lowest on the north facing slope, and the difference was more than 150 W/sq m (20-30 percent) at solar noon. For daily averages the difference was about 25 W/sq m (15 percent) early in the season and increased to about 60 W/sq m (30-50 percent) in September. Soil heat fluxes were similar for all the slopes. The absolute values of sensible heat flux were consistently lower on the north facing slope compared with other slopes. The south facing slope had the greatest day-to-day fluctuation in latent heat flux as a result of the interaction of net radiation, soil moisture, and green leaf area. Differences were found in the partitioning of the available energy among the slopes, and the north facing slope had a higher percentage of energy dissipated into latent heat flux. The north facing slope had higher air temperatures during the day and higher vapor pressures both during the day and at night when the wind was from the south.

Nie, D.; Demetriades-Shah, T.; Kanemasu, E. T.

1992-01-01

143

Alaska North Slope oil-rock correlation study: Analysis of North Slope crude  

Energy Technology Data Exchange (ETDEWEB)

This book contains the results of the Alaska North Slope study. There are 29 selections covered in the following sections: Basic Source Rock Evaluation and Carbon Isotope, Source Rock Evaluation Including Isotopes and Biomarkers, Source Rock Evaluation and Biomarkers, and Specialized or Statistical Approaches.

Magoon, L.B.; Claypool, G.E.

1985-01-01

144

Seismic Stability of Reinforced Soil Slopes  

DEFF Research Database (Denmark)

Over recent decades increased research interest has been observed on the dynamic response and stability issues of earth walls and reinforced soil structures. The current study aims to provide an insight into the dynamic response of reinforced soil structures and the potential of the geosynthetics to prevent the development of slope instability taking advantage of their reinforcing effect. For this purpose, a onedimensional (SDOF) model, based on Newmarkâ??s sliding block model as well as a two-dimensional (plane-strain) dynamic finite-element analyses are conducted in order to investigate the impact of the most significant parameters involved, such as the flexibility of the sliding system, the mechanical properties of the soil and of the geosynthetics material, the frequency content of the excitation and the interface shear strength.

Tzavara, I.; Zania, Varvara

2012-01-01

145

ASPECTS OF DRIP IRRIGATION ON SLOPES  

Directory of Open Access Journals (Sweden)

Full Text Available Nowadays, water and its supply raise problems of strategic importance, of great complexity, being considered one of the keys to sustainable human development. Drip irrigation consists in the slow and controlled administration of water in the area of the root system of the plants for the purposes of fulfilling their physiological needs and is considered to be one of the variants of localized irrigation. Water is distributed in a uniform and slow manner, drop by drop, in a quantity and with a frequency that depend on the needs of the plant, thanks to the exact regulation of the water flow rate and pressure, as well as to the activation of the irrigation based on the information recorded by the tensiometer with regard to soil humidity. This method enables the exact dosage of the water quantity necessary in the various evolution stages of the plant, thus eliminating losses. By applying the irrigation with 5 liters of water per linear meter, at a 7 days interval, in the month of august, for a vine cultivated on a slope, in layers covered with black film and irrigated via dropping, soil humidity immediately after irrigation reaches its highest level, but within the limits of active humidity, on the line of the irrigation band. Three days later, the water content of the soil in the layer is relatively uniform, and, after this interval, it is higher in the points situated at the basis of the film. This technology of cultivation on slopes favors the accumulation, in the soil, of the water resulted from heavy rains and reduces soil losses as a result of erosion.

Oprea Radu

2010-01-01

146

Nocturnal flow on a western Colorado slope  

International Nuclear Information System (INIS)

The Department of Energy sponsored Atomspheric Studies in Complex Terrain (ASCOT) program has conducted a research program designed to increase our knowledge and understanding of terrain-dominated flows with specific emphasis on nocturnal flows within mountain valleys. ASCOT has sponsored both field studies and numerical modeling efforts to improve our understanding of the wind, temperature and turbulence structure of nocturnal drainage flows. One of the most recent ASCOT sponsored field studies involves a study within the Mesa Creek Basin in western Colorado to investigate the seasonal frequency of occurrence of drainage flows along the sloped surfaces and within the basin, and to evaluate the effect of the ambient meteorology on their development. The Mesa Creek Basin, situated on the north slope of the Grand Mesa, encompasses a roughly 10 x 20 km area that is approximately 30 km east of Grand Junction. The observational segment of the study was undertaken jointly by the Lawrence Livermore National Laboratory and the NOAA Wave Propagation Laboratory, and involved the operation of network of eight meteorological towers and a monostatic sodar within the Mesa Creek study area over a period of one year that extended from December 1988 through November 1989. These measurements were augmented by tethersonde observations to define the vertical wind and temperature structure during a few nights. The modeling portion of the study is being undertaken by Lawrence Livermore Laboratory using a three-dimensional prognostic boundary layer model to gain further insight into the dynamics of the seasonal variations and the effect of cloud cover on the development of the drainage flows. It is the purpose of this paper to present preliminary results form a numerical simulation done as part of this study. 4 refs., 7 figs

1990-05-13

147

Plant root reinforcement against local failure mechanism in protecting slope  

Science.gov (United States)

Effectiveness of plant root reinforcement in protecting shallow landslides was investigated with a method of slope stability analysis. In the study, plant roots contributed effectively to increase the local safety factors of slope and subsequently increased the over-all safety factor to stabilize the slope. The natural plant roots increased the local safety factor by providing additional shear strength locally to the shear plane of the investigated slopes. Study showed that the strength of soil at certain location along the shear plane drastically reduced to a residual level and the local failure was imminent for slopes without root reinforcement. On the other hand, the roots significantly contributed additional strength to increase such local residual strength of slope soil and hence increased the safety factor for same slopes with root reinforcements. The shear strengths of roots were determined with root diameters, number of roots and tensile strength of roots. The root shear strengths were incorporated as reinforcements into the slope stability analysis method. The used method for slope stability analysis calculated the local as well as over-all factor of safety with root reinforcement. Existing published data regarding the roots were used in the analyses. A number of analyses for safety factor calculations were done with different root reinforcement situation in the slopes. Parametric studies among different root parameters with safety factor and shear strength were also studied.

Khan, Y. A.

2013-12-01

148

Slope Stability: Factor of Safety along the Seismically Active Continental Slope Offshore Sumatra  

Science.gov (United States)

Recent papers have documented the probability that turbidites deposited along and downslope of subduction zone accretionary prisms are likely the result of strong ground shaking from great earthquakes. Given the damaging nature of these earthquakes, along with the casualties from the associated tsunamis, the spatial and temporal patterns of these earthquakes can only be evaluated with paleoseismologic coring and seismic reflection methods. We evaluate slope stability for seafloor topography along the Sunda subduction offshore Sumatra, Indonesia. We use sediment material properties, from local (Sumatra) and analogous sites, to constrain our estimates of static slope stability Factor of Safety (FOS) analyses. We then use ground motion prediction equations (GMPE's) to estimate ground motion intensity (Arias Intensity, AI) and acceleration (Peak Ground Acceleration, PGA), as possibly generated by fault rupture, to constrain seismic loads for pseudostatic slope stability FOS analyses. The ground motions taper rapidly with distance from the fault plane, consistent with ground motion - fault distance relations measured during the 2011 Tohoku-Oki subduction zone earthquake. Our FOS analyses include a Morgenstern method of slices probabilistic analysis for 2-D profiles along with Critical Acceleration (Ac) and Newmark Displacement (Dn) analysis of multibeam bathymetry of the seafloor. In addition, we also use estimates of ground motion modeled with a 2004 Sumatra-Andaman subduction zone (SASZ) earthquake fault slip model, to also compare with our static FOS analyses of seafloor topography. All slope and trench sites are statically stable (FOS < 1) and sensitive to ground motions generated by earthquakes of magnitude greater than 7. We conclude that for earthquakes of magnitude 6 to 9, PGA of 0.4-0.6 to 1.4-2.5 g would be expected, respectively, from existing GMPE's. However, saturation of accelerations in the accretionary wedge may limit actual accelerations to less than 1 g. Arias intensities of 0.4-1.7 to 7.9-33 m/s are estimated for the M = 6 and M = 9 events, respectively, are expected in the source regions of piggyback basins for local slope failures. Typical sites have Dn means of 0.1, 1.6, 7.7, and 16 cm for earthquakes of M = 6, 7, 8, and 9; suggested thresholds for displacement range between 5 and 10 cm. Thus the observed turbidite stratigraphy in the Sumatra piggyback basins can be explained by local ground motions during earthquakes with magnitude greater than ~7, given the static stability and low sedimentation rates. The paleoseismic data to date suggest a repeat time of 240 years, insufficient to destabilize slopes though sediment accumulation alone.

Patton, J. R.; Goldfinger, C.; Djadjadihardja, Y.; None, U.

2013-12-01

149

Stability Analysis of Cut Slopes Using Continuous Slope Mass Rating and Kinematic Analysis in Rudraprayag District, Uttarakhand  

Directory of Open Access Journals (Sweden)

Full Text Available In mountain terrains of Himalaya, road and highway networks play a vital role in remote areas for transportation, public network and all kind of socio-economic activities. The stability of rock slopes along the roads and highways is a major concern in these hilly regions. Any kind of slope failure may lead to disruption in traffic, loss of properties and lives/injuries as well as environmental degradation. The unplanned excavations of rock slopes for construction or widening purposes may undermine the stability of the slopes. The present study incorporates the stability analysis of road cut slopes along NH-109 which goes to holy shrine of Kedarnath. Slope failure is not only a phenomenon of rainy season but it has also been encountered even in dry season. The study area experiences high vehicular traffic especially from March to August due to pilgrims since it is the only road to Kedarnath. The distance of about 20 km between Rudraprayag and Agastmuni has been investigated. The continuous slope mass rating (CSMR technique has been used for slope stability analysis at five different locations. CSMR is modification of original slope mass rating (SMR proposed by Romana which is based on well established rock mass rating (RMR technique. Kinematic analysis was also carried out to evaluate these sites for types of failure and its potential failure directions. The potentially vulnerable sites were identified. The results indicate that the CSMR technique may be exploited to assess the stability of rock slopes in the Himalayan territory.

R. K. Umrao

2011-10-01

150

Stochastic variant of the Froehlich method for investigating slope stability  

Energy Technology Data Exchange (ETDEWEB)

Calculates the probability of slope failure with a newly developed stochastic model, based on the calculation method of O.K. Froehlich (1950) for slope stability in homogeneous soil. The model replaces the initial deterministic approach with its resulting slope safety value by calculations of failure probability. The model takes into account that parameters such as soil cohesion and soil friction angle may deviate from real vaues in investigations due to soil sampling and sample testing deficiencies. Formulae for slope failure probability are derived in detail and compared to measurements conducted in solid and overconsolidated brown coal mine overburden. Calculation examples of slope failure probability are given for a slope 20 m high and with inclinations of 40 to 65 degrees. The correlative dependence of major parameters and the influence of soil measurement errors are further demonstrated. (9 refs.) (In German)

Foerster, W.; Stoyan, D.; Weber, E.

1981-06-01

151

Distinct Element Modelling of Mahabaleshwar Road Cut Hill Slope  

Directory of Open Access Journals (Sweden)

Full Text Available Reliable estimates of slope stability are essential for safe design and planning of road cut hill slopes which accommo-date a number of tourist destinations around the world. The failure of cut slopes along these hills puts human life in grave danger and it is also disastrous for the economy. In the present study, a section of 100 m high jointed basalt hill slope has been analyzed numerically in a distinct element code, which is apt for simulating the behavior for jointed rock. The analysis was carried out for both the dry and saturated conditions. The distinct element analysis of the hill slope demonstrates it to be marginally stable under dry condition, while for the saturated condition, the hill slope fails along well defined joint planes.

Ashutosh Kainthola

2012-10-01

152

Three-dimensional kinematic controls on rock slope stability conditions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis investigates the three-dimensional influence of discontinuity sets and topography on kinematics of rock slope stability and failure mechanisms. A field data collection methodology was developed to provide the inputs to a slope stability investigation that utilises three-dimensional geometric, limit equilibrium and distinct element codes. Conceptual slope geometries in addition to three case studies are employed to evaluate the influence of discontinuity set orientation and lateral...

Brideau, Marc-andre

2010-01-01

153

The susceptibility of rock slopes to earthquake-induced failure  

Science.gov (United States)

Faulure of rock slopes is a major cause of damage and casualties during moderate and strong earthquakes. This article presents a method for assessing the seismic stability of rock slopes, which can be applied on a regional scale, using data from existing maps, reports, aerial photographs, and reconnaissance-level field observations. The method is based on observed associations between landslide concentrations and slope characteristics in 24 earthquakes that occurred in various parts of the world. -from Author

Keefer, D. K.

1993-01-01

154

Analysis of rainfall infiltration law in unsaturated soil slope.  

Science.gov (United States)

In the study of unsaturated soil slope stability under rainfall infiltration, it is worth continuing to explore how much rainfall infiltrates into the slope in a rain process, and the amount of rainfall infiltrating into slope is the important factor influencing the stability. Therefore, rainfall infiltration capacity is an important issue of unsaturated seepage analysis for slope. On the basis of previous studies, rainfall infiltration law of unsaturated soil slope is analyzed. Considering the characteristics of slope and rainfall, the key factors affecting rainfall infiltration of slope, including hydraulic properties, water storage capacity (?s - ?r), soil types, rainfall intensities, and antecedent and subsequent infiltration rates on unsaturated soil slope, are discussed by using theory analysis and numerical simulation technology. Based on critical factors changing, this paper presents three calculation models of rainfall infiltrability for unsaturated slope, including (1) infiltration model considering rainfall intensity; (2) effective rainfall model considering antecedent rainfall; (3) infiltration model considering comprehensive factors. Based on the technology of system response, the relationship of rainfall and infiltration is described, and the prototype of regression model of rainfall infiltration is given, in order to determine the amount of rain penetration during a rain process. PMID:24672332

Zhang, Gui-rong; Qian, Ya-jun; Wang, Zhang-chun; Zhao, Bo

2014-01-01

155

Drawings of Planar Graphs with Few Slopes and Segments  

CERN Document Server

We study straight-line drawings of planar graphs with few segments and few slopes. Optimal results are obtained for all trees. Tight bounds are obtained for outerplanar graphs, 2-trees, and planar 3-trees. We prove that every 3-connected plane graph on $n$ vertices has a plane drawing with at most ${5/2}n$ segments and at most $2n$ slopes. We prove that every cubic 3-connected plane graph has a plane drawing with three slopes (and three bends on the outerface). In a companion paper, drawings of non-planar graphs with few slopes are also considered.

Dujmovic, V; Suderman, M; Wood, D R; Dujmovic', Vida; Eppstein, David; Suderman, Matthew; Wood, David R.

2006-01-01

156

Tidal propagation in an oceanic island with sloping beaches  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, a new analytical solution for describing the tide-induced groundwater fluctuations in oceanic islands with finite length and different slopes of the beaches is developed. Unlike previous solutions, the present solution is not only applicable for a semi-infinite coastal aquifer, but also for an oceanic island with finite length and different sloping beaches. The solution can be used to investigate the effect of higher-order components and beach slopes on the water table fluctuations. The results demonstrate the effect of higher-order components increases with the shallow water parameter or amplitude parameter and the water table level increases as beach slopes decrease.

Y.-C. Chang

2010-07-01

157

Tidal propagation in an oceanic island with sloping beaches  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, a new analytical solution for describing the tide-induced groundwater fluctuations in oceanic islands with finite length and different slopes of the beaches is developed. Unlike previous solutions, the present solution is not only applicable for a semi-infinite coastal aquifer, but also for an oceanic island with finite length and different sloping beaches. The solution can be used to investigate the effect of higher-order components and beach slopes on the water table fluctuations. The results demonstrate the effect of higher-order components increases with the shallow water parameter or amplitude parameter and the water table level increases as beach slopes decrease.

Y. C. Chang

2010-02-01

158

Distinct Element Modelling of Mahabaleshwar Road Cut Hill Slope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Reliable estimates of slope stability are essential for safe design and planning of road cut hill slopes which accommo-date a number of tourist destinations around the world. The failure of cut slopes along these hills puts human life in grave danger and it is also disastrous for the economy. In the present study, a section of 100 m high jointed basalt hill slope has been analyzed numerically in a distinct element code, which is apt for simulating the behavior for jointed rock. The analysis w...

2012-01-01

159

The Slope Heuristics in Heteroscedastic Regression  

CERN Document Server

We consider the estimation of a regression function with random design and heteroscedastic noise in a non-parametric setting. More precisely, we address the problem of characterizing the optimal penalty when the regression function is estimated by using a penalized least-squares model selection method. In this context, we show the existence of a minimal penalty, defined to be the maximum level of penalization under which the model selection procedure totally misbehaves. Moreover, the optimal penalty is shown to be twice the minimal one and to satisfy a nonasymptotic pathwise oracle inequality with leading constant almost one. When the shape of the optimal penalty is known, this allows to apply the so-called slope heuristics initially proposed by Birg\\'e and Massart (07), which further provides with a data-driven calibration of penalty procedure. Finally, the use of results previously obtained by the author (10), considering the least-squares estimation of a regression function on a fixed finite-dimensional li...

Saumard, Adrien

2011-01-01

160

Slope destabilization during the Messinian Salinity Crisis  

Science.gov (United States)

During the Messinian Salinity Crisis, ~ 6 Myr ago, deep canyons were incised when a huge sea-level drawdown of ~ 1.5 km affected the Mediterranean Sea. Nearly contemporaneously, more than 2 km of evaporites accumulated in the basin. This event was the consequence of a complex interaction of tectonic movements and global sea-level variation associated with climatic evolution. This unusual event ended with the reflooding of the Mediterranean area. In this paper, using seismic line interpretation, we show that several landslides occurred in various parts of the Mediterranean Basin during this crisis. Three of these landslides are well preserved, and their dynamics were analyzed. Modeling of the slope stability demonstrates that these landslides may have been due to (i) the relief created by the deep erosion, and/or (ii) the reflooding, which triggered a pore pressure increase. The relatively small run-out distances of the three landslides suggest propagation in a submarine environment and triggering by sea-level rise.

Gargani, Julien; Bache, François; Jouannic, Gwenael; Gorini, Christian

2014-05-01

 
 
 
 
161

Design of Overall Slope Angle and Analysis of Rock Slope Stability of Chadormalu Mine Using Empirical and Numerical Methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In engineering projects associated with rock mechanic science like open pit mines, assessment and slope stability of mine walls is one of the important performance in generate of these structures. Estimating and knowledge of stable slope angle is one of main parts that should be occurring to special attention in open pit mines studies phase. Considering the importance of economic costs in mining issues, the need for appropriate design slope angle that can cause an adverse minimize project cos...

Mahdi Rasouli Maleki; Mohammad Mahyar; Kambiz Meshkabadi

2011-01-01

162

Stability Analysis of Cut Slopes Using Continuous Slope Mass Rating and Kinematic Analysis in Rudraprayag District, Uttarakhand  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In mountain terrains of Himalaya, road and highway networks play a vital role in remote areas for transportation, public network and all kind of socio-economic activities. The stability of rock slopes along the roads and highways is a major concern in these hilly regions. Any kind of slope failure may lead to disruption in traffic, loss of properties and lives/injuries as well as environmental degradation. The unplanned excavations of rock slopes for construction or widening purposes may unde...

2011-01-01

163

Katabatic flow observations over a steep alpine slope  

Science.gov (United States)

Katabatic flows, or downslope drainage flows, are thermally driven winds generated over sloping terrain when the surface is colder than the adjacent air and synoptic forcing is weak. This near-surface temperature inversion generates a buoyancy field such that denser, cooler air near the surface tends to sink down the slope and form the katabatic flow. Often these flows can be exploited for wind energy, and they are important in predicting pollution transport in mountainous regions and the formation of large cold air pools in valleys and basins. Mean characteristics of katabatic flows over gentle slopes are well documented. However, small-scale observations of turbulence inside the katabatic jet are less common, especially over very steep slopes in highly complex topography. Summertime measurements over a steep slope (36.5°) in a narrow alpine valley (Val Ferret, Switzerland) were taken with the aim of better understanding the near-surface turbulent fluxes that govern the local slope flows. Here, a weak katabatic jet with a height less than 1 m characterizes the mean flow. High-resolution, near-surface temperature measurements suggest a shallow internal boundary layer within the katabatic layer. Additionally, the turbulent heat flux varies significantly over the 6 m measurement layer. Hence, Monin-Obukhov Similarity theory (MOST) may be invalid for steep slopes. Turbulent statistics such as velocity and temperature variances, fluxes of momentum and heat, turbulence kinetic energy (TKE), and turbulent Prandtl number are compared to those obtained in large eddy simulations (LES) of idealized steep sloping terrain.

Oldroyd, Holly; Pardyjak, Eric; Calaf, Marc; Giometto, Marco; Huwald, Hendrik; parlange, Marc

2013-04-01

164

HIRESSS: a physically based slope stability simulator for HPC applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

HIRESSS (HIgh REsolution Slope Stability Simulator) is a physically based distributed slope stability simulator for analyzing shallow landslide triggering conditions in real time and on large areas using parallel computational techniques. The physical model proposed is composed of two parts: hydrological and geotechnical. The hydrological model receives the rainfall data as dynamical input and provi...

Rossi, G.; Catani, F.; Leoni, L.; Segoni, S.; Tofani, V.

2013-01-01

165

HIRESSS: a physically based slope stability simulator for HPC applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

HIRESSS (HIgh REsolution Slope Stability Simulator) is a physically based distributed slope stability simulator for analyzing shallow landslide triggering conditions in real time and on large areas using parallel computational techniques. The physical model proposed is composed of two parts: hydrological and geotechnical. The hydrological model receives the rainfall data as dynamical input and provides the pressure head as perturbation to t...

Rossi, G.; Catani, F.; Leoni, L.; Segoni, S.; Tofani, V.

2013-01-01

166

Wave energy saturation on a natural beach of variable slope.  

Science.gov (United States)

Time series of flow were measured across the inner surf zone during a storm. These data were used to quantify the dependence of wave height (transformed from measured flow) and velocity on local slope and depth. Local depth increased with local slope and was independent of deepwater wave steepness.-from Authors

Sallenger, Jr, A. H.; Holman, R. A.

1985-01-01

167

Slopes and colored Jones polynomials of adequate knots  

CERN Multimedia

Garoufalidis conjectured a relation between the boundary slopes of a knot and its colored Jones polynomials. According to the conjecture, certain boundary slopes are detected by the sequence of degrees of the colored Jones polynomials. We verify this conjecture for adequate knots, a class that vastly generalizes that of alternating knots.

Futer, David; Purcell, Jessica S

2010-01-01

168

Investigation of Wetting Pattern Dimensions on Sloping Lands  

Directory of Open Access Journals (Sweden)

Full Text Available To study the effects of irrigation durations and land slopes on wetting pattern dimensions, some experiments were performed using an emitter with constant discharge of 4 liters per hour by 2, 4, and 6 hours irrigation durations. Experiments were conducted on lands with the slopes of 0, 5, 15 an 25 percent, with silty loam soil texture in 3 replications in Fathali region, Mogan plain, Iran. Results showed that increasing the land slope caused an increment in wetting pattern dimensions and bulk, in constant irrigation durations. When slope increased, the depth of infiltrated water along the emitter had a little decrease which wasn’t significant. The upstream and downstream components of wetting pattern were symmetrical on 0 percent slope but not on steep lands. So, optimizing the water use, which is saved in the soil, depends on the land slope and the crop should be planted 10 to 25 centimeters away from the dripper. The investigation of soil moisture distribution on wetting pattern in slope lands showed that contrary to the flat lands the main part of the moisture is accumulated in lower part of the emitter, and wetting pattern in these sloping lands was larger than in flat lands.

A. Mohammadi

2014-02-01

169

RMS slope of exponentially correlated surface roughness for radar applications  

DEFF Research Database (Denmark)

In radar signature analysis, the root mean square (RMS) surface slope is utilized to assess the relative contribution of multiple scattering effects. For an exponentially correlated surface, an effective RMS slope can be determined by truncating the high frequency tail of the roughness spectrum. The choice of the cutoff frequency and the effect on surface scattering simulations are discussed

Dierking, Wolfgang

2000-01-01

170

SLOPE--a real-time ECG data compressor.  

Science.gov (United States)

An ECG sampled at a rate of 250 samples s-1 or more produces a large amount of redundant data that are difficult to store and transmit. In the paper, a real-time ECG data compressor, SLOPE, is presented. SLOPE considers some adjacent samples as a vector, and this vector is extended if the coming sample falls in a fan spanned by this vector and a threshold angle; otherwise, it is delimited as a linear segment. By this means SLOPE repeatedly delimits linear segments of different lengths and different slopes. The Huffman codes for the parameters to describe this linear segment are transmitted for that linear segment. SLOPEa, which is a slightly modified version of SLOPE, is used to compress ambulatory ECG data. All the operations used by SLOPE and SLOPEa are simple integer operations, both SLOPE and SLOPEa being real-time compressors. Experimental results show that an average of 192 bits per channel per second (bpcs) for each ECG signal is obtained by SLOPE and an average of 148 bpcs for each ECG signal is obtained by SLOPEa. PMID:1857123

Tai, S C

1991-03-01

171

Degradation of terraced slopes in Mediterranean conditions  

Science.gov (United States)

Agricultural terraces with dry-stone walls take the largest area of all man-made landforms in Mediterranean mountain regions. Despite on that their contemporary morphodynamics have not been the subject of many studies. It is a significant problem both from a scientific and a practical point of view. The aim of the study was to estimate the influence of relief, lithology, climatic conditions, methods of wall construction and actual agricultural practice on the degradation of agricultural terraces. A field study was conducted in Greece on 7 plots with the overall area of over 42 000 m2 - on the east Crete and on two Aegean islands - Ikaria and Thera. The analysis was conducted on terraced slopes with gradient of 8-23o, built of granitoids, gneisses, crystalline schists, limestones, crystalline dolomites and volcanic tuffs. There was identified the types of terrace walls. Metrical features of terrace systems were ascertained on the basis of GPS RTK measurement. Terrace material petrography and grain size distribution was identified for regolith an soil samples taken from the selected outcrops which were recognized as being representative for 239 georadar profiles of the joint length of over 2500 m. On that basis the volume of each terrace material was defined. The rills cutting the fields and the walls were measured. The infiltration rate was also taken in 130 points. Reasearch showed that regardless of metrical features of terraces, soil grain size distribution and thickness of the terrace material, the most important reason for the destruction of terrace walls is the abandonment of cultivated areas. Changes in cultivation methods and the introduction of pasturage visibly accelerate the degradation processes. On areas unused for 30 years terrace walls are destroyed on over 25% of their length. It concerns both the areas on which filtration coefficient (k) reaches about 10-5m•s-1 as well as the ones where it is a 100 times lower. The least varied values (10-6-10-5m•s-1) came from the measurements of gneisses and granitogneisses, where muddy sandy and gravelly material prevail. On volcanic tuffs the k coefficient reached the order of magnitude of 10-7-10-5m•s-1. The most varied infiltration rates were observed on limestones and crystalline dolomites - depending on thickness of loamy soil material and density of cracks the k coefficient reached from 5•10-9m•s-1 up to 6•10-4m•s-1. An important factor of slope degradation is also the way of making terrace dry-stone walls, independently of the fact if they are 0,5 m or 3 m high. The walls with buried lower part or situated directly on solid rock which are wider at the foundation are far more lasting than the ones facing stones. In this last case damage takes up to 80% of the length of the walls even on the terraces used nowadays. On Ikaria Island during the field study period well constructed and preserved dry-stone walls survived daily precipitation of 300mm and stay intact.

Tsermegas, I.; D?u?ewski, M.; Biejat, K.; Szynkiewicz, A.

2012-04-01

172

Hydrologic design for riprap on embankment slopes  

International Nuclear Information System (INIS)

Waste impoundments for uranium tailings and other hazardous substances are often protected by compacted earth and clay, covered with a layer of loose rock (riprap). The report outlines procedures that could be followed to design riprap to withstand forces caused by runoff resulting from extreme rainfall directly on the embankment. The Probable Maximum Precipitation for very small areas is developed from considerations of severe storms of short duration at mid-latitudes. A two-dimensional finite difference model is then used to calculate the runoff from severe rainfall events. The procedure takes into account flow both beneath and above the rock layer and approximates the concentration in flow which could be caused by a non-level or slumped embankment. The sensitivity to various assumptions, such as the shape and size of the rock, the thickness of the layer, and the shape of the embankment, suggests that peak runoff from an armored slope could be attenuated with proper design. Frictional relationships for complex flow regimes are developed on the basis of flow through rock-filled dams and in mountain streams. These relationships are tested against experimental data collected in laboratory flumes; the tests provide excellent results. The resulting runoff is then used in either the Stephenson or safety factor method to find the stable rock diameter. The rock sizes determined by this procedure for a given flow have been compared with data on the failure of rock layers in experimental flumes, again with excellent results. Computer programs are included for implementing the method. 15 refs., 21 figs., 9 tabs

1988-01-01

173

Application of distinct element method of toppling failure of slope  

International Nuclear Information System (INIS)

The authors have pointed out, in the latest report, that DEM (Distinct Element Method) seems to be a very helpful numerical method to examine the stability of fissured rock slopes, in which toppling failure would occur during earthquakes. In this report, the applicability of DEM for such rock slopes is examined through the following comparisons between theoretical results and DEM results, referring Voegele's works (1982): (1) Stability of one block on a slope. (2) Failure of a rock block column composed of 10 same size rectangular blocks. (3) Cable force required to make a slope stable. Through above 3 comparisons, it seems that DEM give the reasonable results. Considering that these problems may not be treated by the other numerical methods such as FEM and so on, so DEM seems to be a very useful method for fissured rock slope analysis. (author)

1984-01-01

174

Research on the Slope Protection Mechanism of Roots  

Directory of Open Access Journals (Sweden)

Full Text Available This study aims to investigate the slope protection mechanism of roots. In ecological slope protection, plant roots can fix soil and protect slop through biological and mechanical action. However, previous studies on the slope protection mechanism are still not deep enough and inadequate. By taking four kinds of typical plant roots along Wu-Shen Expressway as the research object, through the indoor tensile test and root morphology observation analysis, the tensile strength and ultimate tension were studied and the influence to the stability of the slope was discussed in this study. The results show that the mean ultimate tension of roots is 7.19~29.96 N. The mean tension of shrub roots is 2~4 times greater than that of herb roots. The ultimate tension of the same plant roots increases with the diameter significantly. To the range of improvement, Shrub roots exceed herb ones. It also indicates that the mean tensile strength of roots are 24.48~74.25 MPa. Compared with the steel HRB235, the tensile strength of herb roots is as great as 1/5~1/3, while Shrub roots is about 1/10~1/5. The slope stability coefficient with plant growing is a positive correlation with roots tension and root number through the sliding surface and is a negative correlation with plants weight. In addition, the slope stability coefficient is related to plant density and root morphology. The test results demonstrate that the roots tension with acute angle or right angle to the landslide surface and the roots shear stiffness with obtuse angle can improve the performance of slope’s anti-slide. Four kinds of plants can improve the stability coefficient of shallow soil. As for the slope protection effect, herbage is superior to shrub. In general, grass-shrub mixed community is the ideal system for slope protection.

Juan Wan

2013-08-01

175

The relevance of the slope for concentration-effect relations  

Energy Technology Data Exchange (ETDEWEB)

Risk analysis is mostly based on a comparison of one value for the exposure to a chemical (PEC) and one value for the sensitivity of biota (NEC). This method enables the determination of an effect to be expected, but it is not possible to quantify the magnitude of that effect. Moreover, it is impossible to estimate the effect of a combination of chemicals. Therefore, it is necessary to use a mathematical function to describe the relation between a concentration and the subsequent effect. These relations are typically based on a log normal or log logistic distribution of the sensitivity of individuals of a species. This distribution is characterized by the median sensitivity (EC{sub 50}) and the variation between the sensitivity of individuals (being a measure for the slope of the relation). Presently the attention is focused on the median, while the slope might be even more important. Relevant exposure concentrations are typically in the range which are found in the left tail of the sensitivity distribution. In this study the slope was determined for 250 chemical-species combinations. The data were derived from original experiments and from literature. The slope is highly dependent on the exposure time; the shorter the exposure time the steeper the slope. If data for a standard exposure time [96 hours] are considered, the total variation in slope can partly be explained by the groups of organisms and chemicals. The slope for heavy metals tends to be less steep as compared to the slope of narcotic organic compounds. The slope for fish and molluscs is steeper than for crustaceans. The results of this study are presently applied in a number of risk analysis studies.

Schobben, H.P.M.; Smit, M.; Schobben, J.H.M.; Hendriks, A.J. [TNO, Den Helder (Netherlands). Lab. for Applied Marine Research

1995-12-31

176

Simulating the seismic behaviour of soil slopes and embankments  

DEFF Research Database (Denmark)

In the current study the clarification of the main assumptions, related to the two most commonly used methods of seismic slope stability analysis (pseudostatic and permanent deformation) is attempted. The seismic permanent displacements and the corresponding seismic coefficients were determined via parametric dynamic numerical analyses taking into account not only the main parameters dominating the seismic slope stability, but also the inherent assumptions of the applied approaches that affect the obtained results. The investigation conclude to a realistic procedure for seismic slope stability assessment based on the application of two simple methods taking into account the impact of the most important factors involved.

Zania, Varvara; Tsompanakis, Yiannis

2010-01-01

177

Alterações radiográficas do tálus no pé torto congênito após liberação cirúrgica pela técnica de McKay / Radiographic abnormalities of the talus in patients with clubfoot after surgical release using the McKay technique  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese OBJETIVO: Analisar as alterações morfológicas do tálus após o tratamento cirúrgico do pé torto congênito pela técnica de McKay. MÉTODO: Foram analisadas, retrospectivamente, radiografias em perfil com carga dos pés de 14 pacientes com pé torto congênito unilateral submetidos ao tratamento pela técni [...] ca de McKay por dupla incisão. Todos os pacientes foram operados pelo mesmo cirurgião, com média de 6,53 anos entre a cirurgia e a radiografia. Comparamos as características do tálus dos pés operados com os parâmetros radiográficos dos pés contralaterais. Avaliamos a presença de deformidade do dômus e da cabeça do tálus (avaliação da esfericidade); a altura e o comprimento do tálus; a presença e grau de subluxação do navicular; a alteração do ângulo de Gissane; e o padrão do trabeculado ósseo. RESULTADOS: Alterações da cabeça do tálus ocorreram em 92,8% dos casos; do dômus em 92,8%; e do trabeculado em 100%. A relação entre o comprimento do tálus do pé operado sobre o contralateral variou de 0,61 a 0,88 (média de 0,79; DP = 0,09), e da altura de 0,57 a 0,98 (média de 0,82; DP = 0,12). O ângulo de Gissane aumentou em todos os pés operados, e todos apresentaram subluxação do navicular, com índice variando de 6,43 a 59,75% (média de 26,34%; DP = 16,66%). CONCLUSÃO: Alterações talares ocorreram em 100% dos pés tratados pela técnica de McKay. Estabelecer parâmetros radiográficos para descrever e quantificar essas deformidades mostrou-se viável, através de técnicas simples e de fácil execução. Abstract in english OBJECTIVE: To analyze morphological abnormalities of the talus in patients with clubfoot after surgical treatment using the McKay technique. METHOD: Lateral standing-position radiographs of the feet of 14 patients with unilateral clubfoot who underwent treatment by means of the double-incision McKay [...] technique were retrospectively analyzed. All the patients were operated by the same surgeon, with an average of 6.53 years between surgery and the radiograph. We compared the radiographic characteristics of the talus between the operated and the contralateral foot. We assessed the presence of deformity of the talar dome and head (sphericity evaluation); the talar length and height; the percentage and degree of navicular subluxation; abnormalities of the Gissane angle; and the trabecular bone pattern. RESULTS: Abnormalities of the talar head occurred in 92.8% of the patients; of the talar dome in 92.8%; and of the trabecular pattern in 100%. The talar length ratio between the operated and the contralateral foot ranged from 0.61 to 0.88 (mean 0.79; SD = 0.09), while the height ratio ranged from 0.57 to 0.98 (mean 0.82; SD = 0.12). The Gissane angle was greater in all of the operated feet, and all of them also showed navicular subluxation, at a rate ranging from 6.43 to 59.75% (mean 26.34%; SD = 16.66%). CONCLUSION: Talar abnormalities occurred in 100% of the feet treated using the McKay technique. It was shown that establishing radiographic parameters to describe and quantify these deformities was feasible, through simple and easy-to-perform techniques.

José Antonio, Pinto; Andréa Canizares, Hernandes; Thais Paula, Buchaim; Francesco Camara, Blumetti; Carla, Chertman; Patrícia Corey, Yamane; Artur da Rocha Corrêa, Fernandes.

178

Examining the Relation of Osteochondral Lesions of the Talus to Ligamentous and Lateral Ankle Tendinous Pathologic Features: A Comprehensive MRI Review in an Asymptomatic Lateral Ankle Population.  

Science.gov (United States)

Given the frequency and burden of ankle sprains, the pathologic features identified on magnetic resonance imaging (MRI) scans are widely known in the symptomatic population. Ankle MRI pathologic features in the asymptomatic population, however, are poorly understood. Such examinations are rarely undertaken unless an ankle has been injured or is painful. We report the systematic MRI findings from the reports of 108 consecutive asymptomatic lateral ankles (104 patients). Our purpose was to (1) report the prevalence of osteochondral lesions of the talus (OLTs) and pathologic features of the medial and lateral ligaments, peroneal tendons, and superior peroneal retinaculum (SPR); (2) correlate the presence of OLTs with the pathologic features of the medial and lateral ligaments, peroneal tendons, and SPR; and (3) correlate ligamentous discontinuity with the peroneal pathologic features, OLTs, and SPR pathologic features. A total of 16 OLTs (14.81%) were present (13 medial and 3 lateral). Of the 16 patients with OLTs, 8 (50.00%) had concomitant peroneal pathologic findings. Healthy medial and lateral ligaments were noted in 41 patients (37.96%), and ligamentous discontinuity was grade I in 25 (23.15%), II in 32 (29.63%), III in 5 (4.63%), and grade IV in 5 patients (4.63%). A weak positive correlation was found between attenuation or tears of the superficial deltoid and medial OLTs (phi coefficient = 0.23, p = .0191) and a moderate positive correlation between tears of the posterior talofibular ligament and lateral OLTs (phi coefficient = 0.30, p = .0017). Additionally, a moderate positive correlation between ligamentous discontinuity and tendinopathy of the peroneus brevis was noted [Spearman's coefficient(106) = 0.29, p = .0024]. These findings add to the evidence of concomitant pathologic features in the asymptomatic population. To definitively assess causation and evaluate the clinical evolution of radiologic findings, future, prospective, longitudinal cohort studies are necessary. PMID:24796886

Galli, Melissa M; Protzman, Nicole M; Mandelker, Eiran M; Malhotra, Amit D; Schwartz, Edward; Brigido, Stephen A

2014-01-01

179

Establishment Criteria for Visual Approach Slope Indicator (VASI).  

Science.gov (United States)

This report develops revised establishment and discontinuance criteria for Visual Approach Slope Indicator (VASI) which provide Visual Flight Rules (VFR) guidance only. Criteria are based upon detailed benefit/cost methodology. This approach takes into ac...

J. Roman

1977-01-01

180

Procedures for Design of Earth Slopes Using LRFD.  

Science.gov (United States)

This report describes a proposed procedure and process for implementation of LFRD for slope stability analysis applications, including evaluation of overall stability of earth retaining structures. Two sets of load and resistance factors are present. The ...

J. E. Loehr C. A. Finley D. Huaco

2005-01-01

 
 
 
 
181

Effect of a weak layer in slope stability  

Energy Technology Data Exchange (ETDEWEB)

The objective of this paper is to present a practical method for calculating minimum safety factors of rock slopes with a horizontal layer of weak material. It is demonstrated that the most critical failure surface, in this case, is a bilinear surface composed of a horizontal failure surface inside the weak layer and an inclined surface inside the rock. The model presented in this paper shows that with a good approximation, the change in slope for the bilinear failure surface may occur directly below the slope crest. This assumption simplifies the calculation of safety factors considerably, because the most critical failure surface is located directly, and the trial computations for a number of failure surfaces are not necessary. Special parameters involved in slope stability analyses of highwalls in open-pit mines are discussed and, by an example calculation, the applicability of this method is demonstrated.

Vakili, J.

1984-01-01

182

POTENTIALLY UNSTABLE SLOPE ABOVE ORE PROCESSING PLANT IN THE  

Directory of Open Access Journals (Sweden)

Full Text Available The complex engineering investigation, in the nearest surroun-dig of the conditionally stable high slope, close to ore processing facilities in the dolomite quarry »O?ura« near Lepoglava (North Croatia, was carried out. Studying the tectonic features of the rock mass, discontinuities referent to the slope stability, was found out. Rock fragment size was measured and data processed using statistical design. According to rock fragment mean values, velocity of the longitudinal seismic waves was predicted. This values was compared with velocities of the longitudinal seismic waves, determined using gcophisical refraction seismic method. Physical and mechanical properties of the dolomite rock mass, considering longitudinal and transversal seismic wave velocities, and »RMR«-classification was assesed. All the results indicate, that the slope above the ore processing facilities should be consider as conditionally stable, with real probability to get unstable under the vibrations caused by blasting, during the exploitation in the field, close behind the investigated slope.

Ivan Baturi?

1993-12-01

183

Impact Analysis of Blasting Vibration on the Slope and Dump  

Directory of Open Access Journals (Sweden)

Full Text Available As known that the blasting on the slope is very dangerous in the exploration of the mine andneeds complex analysis and calculation on the slope and dump. In the study it adopts the regression method in the analysis of important parameters of the vibration experiments of iron ore stope which influence the stability of slope and vibration velocity of mine blasting, vibration acceleration, etc., it makes the analysis of power spectrum and dynamic response. Through the model of landslide dynamic response it analyzes the rule of blasting vibration and the blasting vibration influence on the stability of slope, the research can provide a safety criterion in the exploitation of the iron ore.

Zhang De

2014-01-01

184

Drawing planar graphs of bounded degree with few slopes  

CERN Multimedia

We settle a problem of Dujmovi\\'c, Eppstein, Suderman, and Wood by showing that there exists a function $f$ with the property that every planar graph $G$ with maximum degree $d$ admits a drawing with noncrossing straight-line edges, using at most $f(d)$ different slopes. If we allow the edges to be represented by polygonal paths with {\\em one} bend, then $2d$ slopes suffice. Allowing {\\em two} bends per edge, every planar graph with maximum degree $d\\ge 3$ can be drawn using segments of at most $\\lceil d/2\\rceil$ different slopes. There is only one exception: the graph formed by the edges of an octahedron is 4-regular, yet it requires 3 slopes. These bounds cannot be improved.

Keszegh, Balázs; Pálvölgyi, Dömötör

2010-01-01

185

Influence of Rainfall Patterns on the Instability of Slopes  

Directory of Open Access Journals (Sweden)

Full Text Available The assessment of rainstorm-induced shallow landslides is still a research topic of wide concern for scientists and engineers. This paper examined the effect of rainfall intensity distribution on shallow landslides. Four synthetic rainfall distributions comprising uniformed, delayed, centralized, and advanced, were selected to examine the effect of rainstorm patterns on slope failure. The infiltration was modeled using Green-Ampt equation, while an infinite slope was selected to model the shallow landslide. Monte Carlo Simulation was applied to analyze the failure probability of the slopes. Two landslide cases were selected to examine the proposed model. The results indicated that among the four representative rainstorm patterns, the advanced rainfall pattern caused worst slope stability. The advanced rainfall pattern resulted in the shortest rainfall duration threshold for landslide occurrence, followed by the central, uniform, and then delayed rainfall pattern. The probabilistic analysis method was suitable to estimate the time of failure for the evaluated landslide cases.

Muntohar A.S.

2013-01-01

186

The stability of grounding lines on retrograde slopes  

Directory of Open Access Journals (Sweden)

Full Text Available The stability of marine ice sheets grounded on beds that slope upwards in the overall direction of flow is investigated numerically in two horizontal dimensions. We give examples of stable grounding lines on such retrograde slopes illustrating that marine ice sheets are not unconditionally unstable in two-horizontal dimensions. Retrograde bed slopes at the grounding lines of maritime ice sheets, such as the West Antarctic Ice Sheet (WAIS, do not per se imply an instability, nor do they imply that these regions are close to a threshold of instability. We therefore question those estimates of the potential near-future contribution of WAIS to global sea level change based solely on the notion that WAIS, resting on retrograde slope, must be inherently unstable.

G. H. Gudmundsson

2012-07-01

187

The stability of grounding lines on retrograde slopes  

Directory of Open Access Journals (Sweden)

Full Text Available The stability of marine ice sheets grounded on beds that slope upwards in the overall direction of flow is investigated numerically in two horizontal dimensions. We give examples of stable grounding lines on such retrograde slopes illustrating that marine ice sheets are not unconditionally unstable in two horizontal dimensions. Retrograde bed slopes at the grounding lines of marine ice sheets, such as the West Antarctic Ice Sheet (WAIS, do not per se imply an instability, nor do they imply that these regions are close to a threshold of instability. We therefore question those estimates of the potential near-future contribution of WAIS to global sea level change based solely on the notion that WAIS, resting on a retrograde slope, must be inherently unstable.

G. H. Gudmundsson

2012-12-01

188

Oracle approach and slope heuristic in context tree estimation  

CERN Document Server

We introduce a general approach to prove oracle properties in context tree selection. The results derive from a concentration condition that is verified, for example, by mixing processes. Moreover, we show the superiority of the oracle approach from a non-asymptotic point of view in simulations where the classical BIC estimator has nice oracle properties even when it does not recover the source. Our second objective is to extend the slope algorithm of \\cite{AM08} to context tree estimation. The algorithm gives a practical way to evaluate the leading constant in front of the penalties. We study the slope heuristic underlying this algorithm and obtain the first results on the slope phenomenon in a discrete, non i.i.d framework. We illustrate in simulations the improvement of the oracle properties of BIC estimators by the slope algorithm.

Garivier, A

2011-01-01

189

Stability Analysis and Stability Chart for Unsaturated Residual Soil Slope  

Directory of Open Access Journals (Sweden)

Full Text Available In tropical residual soils most hill slope failures are caused by rainfall. It is therefore important to consider dynamic hydrological conditions when attempting to analyze the stability of residual soil slopes. This paper describes a coupled hydrology/stability model that has been developed to overcome the limitations of the standard method of analysis used to investigate stability of tropical soil slopes. A computational hydrology ? limit equilibrium stability analysis model is outlined and examples are provided of the model output capabilities in terms of design charts. Although nowadays most realistic problem should be analyzed by computer and stability charts are mainly used to analyze simple slopes, they can be useful for preliminary analysis and enable the designer to quickly assess the sensitivity of a problem to changes in different input parameters.

Bugang B.K. Haut

2006-01-01

190

Interpretation of Schubert plot slopes for metal-humate systems  

International Nuclear Information System (INIS)

In this paper an error in the literature is identified pertaining to the interpretation of nonintegral slopes in Schubert plots for metal-humate and metal-fulvate systems. Equations are derived that correctly describe the behavior of these systems

1986-01-01

191

Application of distinct element method to toppling failure of slopes  

International Nuclear Information System (INIS)

Recently, the stability of slopes during earthquakes has become to be an important engineering problem, especially in case of the earthquake-proof design of nuclear power plants. But, for fissured rock slopes, some problems are remained unresolved, because they can not be treated as continua. The authors have been investigating toppling failure of slopes, from a point of view which regards a fissured rock mass as an assemblage of rigid blocks. DEM (Distinct Element Method) proposed by Cundall (1974) seems to be very helpful to such a investigation. So, in this paper, the applicability of DEM to toppling failure of slopes is examined through the comparison between DEM results and theoretical or experimental results using 3 simple models. (author)

1985-01-01

192

Dynamic Stability of Rock Slopes and Gravel Beaches,  

Science.gov (United States)

More than 150 tests have been analyzed in order to describe the dynamically stable profiles of rock slopes and gravel beaches under wave attack. Relationships between profile parameters and boundary conditions have been established. These relationships ha...

J. W. van der Meer K. W. Pilarczyk

1987-01-01

193

Steep Cut Slope Composting: Field Trials and Evaluation.  

Science.gov (United States)

Three different depths of compost and five compost retention techniques were tested to determine their efficacy and cost effectiveness for increasing the establishment of native grass seedings and decreasing erosion on steep roadside cut slopes in southwe...

P. Blicker R. Ament S. Jennings

2011-01-01

194

The evolution of slope failures: mechanisms of rupture propagation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Forecasting the occurrence of large, catastrophic slope failures remains very problematic. It is clear that in order advance this field a greater understanding is needed of the processes through which failure occurs. In particular, there is a need to comprehend the processes through which a rupture develops and propagates through the slope, and the nature of the inter-relationship between the stress and strain states of the landslide mass. To this end, a detailed analysis has been undertaken ...

Petley, D. N.

2004-01-01

195

Slopes of trigonal fibred surfaces and of higher dimensional fibrations  

CERN Multimedia

We give lower bounds for the slope of higher dimensional fibrations over curves under conditions of GIT-semistability of the fibres, using a generalization of a method of Cornalba and Harris. With the same method we establish a sharp lower bound for the slope of trigonal fibrations of even genus and general Maroni invariant; in particular this result proves a conjecture due to Harris and Stankova-Frenkel.

Barja, Miguel A

2008-01-01

196

Analysis of slope stabilization by soil bioengineering method  

Science.gov (United States)

The aim of the project is to create a numerical model which will include the impact of vegetation on the slope stability analysis, considering both mechanical and hydrological factors. This will enrich the current knowledge about how roots reinforce the soil layers on the slope and how it influences the increase of shear strength of the soil. This has to be combined together with hydrological effects caused by evapotranspiration: modified soil moisture regime, dissipation of excess pore pressure and established matric suction. Coupled analyses (mechanical and hydrological) are rarely conducted, or only outdated models are used, which leads to overestimation of the additional shear strength of soil. That is why there is a need to support this branch of landslide hazard assessment and develop a new model. This research will help to raise awareness, that soil bioengineering methods of slope stabilization can in some cases be more appropriate and less expensive than traditional methods. As an input to the model, the appropriate slope geometry and soil properties have to be chosen. It is also important to consider different plant types and root properties, as well as different levels of groundwater table. To assess the effect of evapotranspiration it is necessary to know the geographical location of the slope and the weather conditions in the chosen region. The final output of the model, which will help to quantitatively assess the impact of vegetation on the slope stability, is the factor of safety (FOS) for vegetated slope for different types of soil and degrees of saturation. Results may then be compared with different conditions and factors of safety, calculated for the corresponding non-vegetated slope. It will be possible to specify the most favorable and unfavorable conditions. Moreover, the calculations provide also information on changes of cohesion, caused by mechanical and hydrological effects, as well as the change in the friction angle of soil.

Switala, Barbara Maria; Wu, Wei

2013-04-01

197

Assessment of overgrazing on degradation of sloping soil  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Overgrazing, particularly on slopes, can cause significant alterations in soil quality, determining a greater vulnerability to soil erosion. The aim of this work was to assess the influence of horse overgrazing on sloping (20%) soil properties. Chemical and biochemical parameters have been determined in order to evaluate soil quality. A significant decrease in nutrients was observed after one year. The trend of enzyme activities highlighted a reduction of metabolic processes. However, after o...

Bondi, Giulia; Peruzzi, Eleonora; Macci, Cristina; Doni, Serena; Masciandaro, Grazia; Pistoia, Alessandro

2012-01-01

198

Slope Stability Evaluations by Limit Equilibrium and Finite Element Methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis deals with slope stability evolutions carried out by commonly used limit equilibrium (LE) and finite element (FE) methods. The study utilizes two LE based software (SLOPE/W and SLIDE) and one FE based software (PLAXIS). The principal difference between these two analyses approaches is that the LE methods are based on the static of equilibrium whereas FE methods utilise the stress?strain relationship or constitutive law. To fulfil one of the aims of the study, the LE based meth...

2006-01-01

199

Slope Stability Evaluations by Limit Equilibrium and Finite Element Methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis deals with slope stability evolutions carried out by commonly used limit equilibrium (LE) and finite element (FE) methods. The study utilizes two LE based software (SLOPE/W and SLIDE) and one FE based software (PLAXIS). The principal difference between these two analyses approaches is that the LE methods are based on the static of equilibrium whereas FE methods utilise the stress?strain relationship or constitutive law. To fulfil one of the aims of the study, the LE based metho...

2006-01-01

200

SLOPE - A metaphor-based strategy formation tool  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this era of technological advances and globalization, strategy formation tools such as SWOT (Strengths, Weaknesses, Opportunities and Threats) have been frequently criticized as inadequate. Following a review of ten different schools of thought on strategy formation, this thesis introduces a new strategy formation tool -SLOPE (Strengths, Limitations, Obstacles and Potential Excellence) - and describes its application in a test pilot and three case studies. SLOPE uses a metaphor and story e...

Moody, Shona

2005-01-01

 
 
 
 
201

Rock slope stability of the quarries of Estremoz marble zone  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Estremoz Marble Zone is one of the most important dimension stone production centre in the World. In these quarries located in the Alentejo Region (Southern Portugal), rock slopes, some of them with more than one hundred meters high, has been mined. This work emphasizes structural control in the marble quarrying and presents a case study, in which the analysis of the stability of a slope was based on a geological and structural

2010-01-01

202

Kinetics of crimp and slope grip in rock climbing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim was to investigate differences of the kinetics of the crimp and the slope grip used in rock climbing. Nine cadaver fingers were prepared and fixated with the proximal phalanx in a frame. The superficial (FDS) and deep (FDP) flexor tendons were loaded selectively and together with 40 N in the crimp grip (PIP joint flexed 90°/DIP joint hyperextended) and the slope grip position (<25° flexed/50° flexed respectively). Five different grip sizes were tested and the flexion force which wa...

Schweizer, A.; Hudek, R.

2011-01-01

203

Patterns of precursory rockfall prior to slope failure  

Science.gov (United States)

In this paper we examine data generated using high-resolution three-dimensional laser scanning monitoring of coastal rock cliffs. These data are used to identify spatial and temporal patterns in rockfall activity behavior prior to slope failure. Analysis of the data suggests that given sufficient measurement precision precursory behavior, here manifest as the rate of rockfall activity prior to failure, can be detected, measured, and monitored. Environmental conditions appear to have a diminishing influence on the occurrence of increasingly large slope failures. The monitoring data implies a time-dependent sequence in the occurrence of smaller rockfalls in the period leading to the largest failures recorded. This behavior is attributed to the mechanisms of strain accumulation in the rock mass resulting from brittle failure of the slope. The implication is that combining these data with models of failure mechanisms may allow failure time to be forecast from wide-area monitoring of precursory behavior. These findings have implications for the management of potentially unstable slopes, the understanding of slope failure mechanisms, and the generation of a new type of slope failure warning systems.

Rosser, Nick; Lim, Michael; Petley, David; Dunning, Stuart; Allison, Robert

2007-12-01

204

Exploring Benthic Biodiversity Patterns and Hotspots on European Margin Slopes  

Directory of Open Access Journals (Sweden)

Full Text Available There is increasing evidence that continental slope ecosystems represent one of the major repositories of benthic marine biodiversity. The enhanced levels of biodiversity along slopes are hypothesized to be a source of biodiversity for continental shelves and deeper basins. Continental margins are increasingly altered by human activities, but the consequences of these anthropogenic impacts on benthic biodiversity and ecosystem functioning are almost completely unknown. Thus, there is an urgent need to gather sufficient information to enable us to understand patterns and drivers of deep-sea biodiversity along continental margins. Although the local diversity of some deep open slope ecosystems is moderately well documented, very little is known about the biodiversity of these systems at greater spatial scales. Topographic setting, hydrodynamic forcing, and the biogeochemical characteristics of the deep-sea floor may play key roles in promoting and sustaining high biodiversity along the open slopes of continental margins. HERMES provided the opportunity to acquire a significant volume of information on the biodiversity, trophic conditions, and topographic characteristics of open slopes across European margins, increasing our knowledge of the latitudinal, longitudinal, and bathymetric patterns of benthic biodiversity, and extending our comprehension of the mechanisms driving deep-sea biodiversity and its potential loss. Improved knowledge of these processes is needed to inform policy decisions for promoting sustainable management of open slopes and deep-sea ecosystems along continental margins.

Roberto Danovaro

2009-03-01

205

Coupled volume/double slope subjective listening test  

Science.gov (United States)

Can experienced listeners of music discern a double-sloped decay from a Sabine decay? Do they prefer the double slope? Concert hall designers use coupled-volumes and their signature double-slope sound decay in an effort to reconcile the inversely related qualities of reverberance and clarity. A simulated space, based on an actual built coupled-volume hall, was conceived in the room acoustics software CATT-Acoustic. Variations in the aperture sizes that sonically expose the main hall to the coupled volume generated both classic Sabine decays and double-sloped decays. The impulse responses generated were convolved with the same anechoic musical recording, grouped in pairs, and played for an opportunity-sample of 21 volunteers from the Architectural Acoustics section of the 145th meeting of the Acoustical Society of America in Nashville. Participants listened to the 11 recorded pairs over headphones and were asked to determine (1) if the two recordings sounded different, (2) which recording was more likely to have a double slope or had a more dramatic double slope, and (3) which of the two recordings they prefer.

Ermann, Michael; Stuecker, Rebecca

2003-10-01

206

Quantifying Slopes with Digital Elevation Models of the Verdugo Hills, California: Effects of Resolution  

Science.gov (United States)

Quantification of surface slope angles is valuable in a wide variety of earth sciences. Slopes measured from digital elevation models (DEMs) or other topographic data sets depend strongly on the length scale or window size used in the slope calculations.

Fielding, E. J.; Burbank, D. W.; Duncan, C. C.

1996-01-01

207

Soil properties in high-elevation ski slopes  

Science.gov (United States)

The development of winter sports determines an increasing impact on the high altitude ecosystems, as a consequence of increased participation and an increasing demand of high quality standards for skiable areas. The construction of a ski slope is associated with a certain impact on soil, which varies as a function of the degree of human-induced disturbance to the native substrata. In this work, we provide a description of the characteristics of alpine tundra ski-slope soils and their nutrient status, contrasted with undisturbed areas. The study site is located in the Monterosaski Resort, Aosta Valley, NW Italy (45°51' N; 7°48' E). We chose 5 sites along an altitudinal gradient between 2700 and 2200 m a.s.l.. Per each site, one plot was established on the ski slope, while a control plot was chosen under comparable topographic conditions a few meters apart. Soils were described and samples were collected and analysed for main chemical-physical properties. In addition an evaluation of N forms, organic matter fractionation and microbial biomass was carried out. Soil depth ranged between 10 to more than 70 cm, both on the ski slope and in the undisturbed areas. A true organo-mineral (A) horizon was firstly identified at 2500 m a.s.l., while a weathering horizon (Bw) was detected at 2400 m a.s.l.. However, a Bw horizon thick enough to be recognised as diagnostic for shifting soil classification order from Entisols to Inceptisols (USDA-Soil Taxonomy) was detected only below 2400 m a.s.l.. Lithic Cryorthents were predominant in the upper part of the sequence (above 2500 m a.s.l.), both in the ski slope and the undisturbed areas; Typic Cryorthents were identified between 2500 and 2400 m a.s.l., while Inceptisols were predominant between 2400 and 2200 m a.s.l.. Chemical-physical properties will be discussed focusing on the main differences between ski slope and undisturbed soils, as determined by the ski slope construction. Pedogenetic processes at high altitude are strongly limited by extreme climatic conditions, resulting in low resistance and resilience with respect to any human-induced changes; therefore, it is key to quantify the impact of ski slope construction and management on such fragile pedo-ecosystems. KEYWORDS: alpine tundra, pedogenesis, ski slope construction, ski slope management

Filippa, Gianluca; Freppaz, Michele; Letey, Stéphanie; Corti, Giuseppe; Cocco, Stefania; Zanini, Ermanno

2010-05-01

208

Eastern Olympus Mons Basal Scarp: Potential for active slope mobilization?  

Science.gov (United States)

The volcanic edifice of Olympus Mons is surrounded by presumed mass-movement landforms known as the aureole deposits. It has been suggested that the aureole deposits are the result of a catastrophic failure of the volcanic edifice. Tantalizingly, a topographic examination of the Eastern flank of Olympus Mons suggests that a large failure may have been captured. The flank exhibits a ~ 80 km near-continuous extensional fracture, bounded on either side by radial tear faults, that cut both the scarp face, and the more recent lava flows that have modified the basal scarp. Observed along fault offsets are on the order of 100 m. A compressional toe, parallel and downslope to the extensional fracture, may be linked and the result of downslope movement of the flank. If so, then a significant portion of the outer edge of the Eastern basal scarp may define a coherent zone of slope instability, or failure. Using digital elevation models derived from HRSC data, several transects along the basal scarp slope face are analyzed to better understand and quantify the stability of each section of the eastern slope, and examine potential failure conditions and mechanisms. Slope stability analysis is used to determine the likelihood of the Eastern basal scarp experiencing a catastrophic failure along the entire fault trace. This result may indicate an active failure process that can lead to an aureole type deposit. If this failure were to occur, a simple case of a curvilinear slip surface connecting the up-slope extensional and down-slope compressional fault traces produces an estimate for the potential mobile landslide volume on the order of 1000 cubic km, or ~ 5-10% of the volume previously estimated for the aureole lobe off of the east flank of Olympus Mons. Preliminary results from topography show that numerous smaller-scale localized slope failures that are emplaced upon young lava flows have occurred along this section of the basal scarp, suggesting significant instability and a strong potential for failure.

Weller, M. B.; McGovern, P. J.; Fournier, T.; Katz, O.; Morgan, J. K.

2011-12-01

209

Slope Length Estimation of Topographic Factor in Watershed using GIS  

Directory of Open Access Journals (Sweden)

Full Text Available Water erosion is a severe and extended issue affecting all over the Loess Plateau, Northwest China. In order to estimate soil loss in China, Chinese Soil Loss Equation (CSLE were used to estimate soil erosion in the Forth China Soil Erosion Survey. CSLE was developed at an individual farmstead scale according to the erosion environment of the Loess Plateau. The equation has a similar calculation way with the universal soil loss equation (USLE and its’ revised version the revised universal soil loss equation (RUSLE. However, a major limitation is the difficulty in extracting the Topographic factor. The extraction method of slope gradient is already widely used and integrated in some applications. How to extract slope length in watershed is still a big problem for applying the USLE, RUSLE and CSLE to calculate soil erosion. The unit contributing area-based estimation method (UCA converts slope length to unit contributing area for considering two-dimensional topography, however is not able to predict the different zones of soil erosion and deposition. The flowpath and cumulative cell length-based method (FCL overcomes this disadvantage but does not consider channel networks, flow convergence and divergence flow in three-dimensional topography. The aim of this paper is to propose an algorithm that extends the FCL method and revise its calculation algorithm for slope length. Using the concept of the multiple flow direction algorithm (MFD with a focus on the calculation of slope length including slope changes. A calculation process is shown and a comparison of results for slope length calculated by FCL and LS-TOOL method (this paper for Xiannangou catchment is presented.

Hongming Zhang

2013-06-01

210

Simulation of a sloped solar chimney power plant in Lanzhou  

International Nuclear Information System (INIS)

Research highlights: ? A sloped solar chimney power plant in Lanzhou, China is investigated. ? The configuration sizes are designed separately. ? The system has high periodicity and stability but low efficiency. ? The sloped solar chimney power system is of high value for Northwest China. -- Abstract: Solar chimney power system is one large-scale utilization style of solar energy, which has drawn high attentions worldwide. Though scholars all over the world have made many researches on the solar chimney power system, reports of sloped solar chimney power system are still few. A sloped solar chimney power plant, which is expected to provide electric power for remote villages in Northwest China, has been designed for Lanzhou City in this paper. The designed plant, in which the height and radius of the chimney are 252.2 m and 14 m respectively, the radius and angle of the solar collector are 607.2 m and 31o respectively, is designed to produce 5 MW electric power on a monthly average all year. The performances, such as the airflow temperature increase, pressure, the airflow speed, system efficiency and solar collector efficiency, of the built sloped solar chimney power plant are simulated and presented. Simulation results show that parameters of the sloped solar chimney power plant are symmetrical and stable; the power plant has better performances in spring and autumn days; the overall efficiency of the power plant is low. Considering the abundant solar radiation, environmental friendliness, easy management and low population density, the sloped solar chimney power system is of high value to Northwest China.

2011-06-01

211

Very rare Q-slope none overcome by electropolishing and baking  

International Nuclear Information System (INIS)

We discovered the very rare Q-slope none overcome by electropolishing and baking at 120degC for 48 hours. The Q-slope is not related to 'Hydrogen disease'. The Q-slope is not improved by the wiping and steam so that we recognize that the Q-slope is not caused by some cohesion things of the cavity's surface. The rare Q-slope is categorized a low, medium and high rare Q-slope. In this paper, we report the Rare Q-slope and the categorized rare Q-slope. (author)

2011-08-01

212

Slope stability probability classification, Waikato Coal Measures, New Zealand  

Energy Technology Data Exchange (ETDEWEB)

Ferm classified lithological units have been identified and described in the Waikato Coal Measures in open pits in the Waikato coal region. These lithological units have been classified geotechnically by mechanical tests and discontinuity measurements. Using these measurements slope stability probability classifications (SSPC) have been quantified based on an adaptation of Hack's [Slope Stability Probability Classification, ITC Delft Publication, Enschede, Netherlands, vol. 43, 1998, 273 pp.] SSPC system, which places less influence on rock quality designation and unconfined compressive strength than previous slope/rock mass rating systems. The Hack weathering susceptibility rating has been modified by using chemical index of alteration values determined from XRF major element analyses. Slaking is an important parameter in slope stability in the Waikato Coal Measures lithologies and hence, a non-subjective method of assessing slaking in relation to the chemical index of alteration has been introduced. Another major component of this adapted SSPC system is the inclusion of rock moisture content effects on slope stability. The main modifications of Hack's SSPC system are the introduction of rock intact strength derived from the modified Mohr-Coulomb failure criterion, which has been adapted for varying moisture content, weathering state and confining pressure. It is suggested that the subjectivity in assessing intact rock strength within broad bands in the initial SSPC system is a major weakness of the initial system. Initial results indicate a close relationship between rock mass strength values, calculated from rock mass friction angles and rock mass cohesion values derived from two established rock mass classification methods (modified Hoek-Brown failure criteria and MRMR) and the adapted SSPC system. The advantage of the modified SSPC system is that slope stability probabilities based on discontinuity-independent and discontinuity-dependent data and a maximum slope height are predicted. The modified SSPC system may be useful in predicting initial optimum pit slope designs in proposed greenfield mine sites. XRF major element and chemical index of alteration (CIA) results obtained for lithologies in the Waikato coal region may be a useful mine management tool to quantify stratigraphic thickness and palaeoweathering from wash drill cuttings. This paper explains the systematic approach of using the adapted SSPC system to classify slope stability in the Waikato open pit coal mines.

Lindsay, P.; Gillard, G.R.; Moore, T.A. [CRL Energy, PO Box 29-415, Christchurch (New Zealand); Campbell, R.N.; Fergusson, D.A. [Solid Energy North, Private Bag 502, Huntly (New Zealand)

2001-01-01

213

Slope Error Measurement Tool for Solar Parabolic Trough Collectors: Preprint  

Energy Technology Data Exchange (ETDEWEB)

The National Renewable Energy Laboratory (NREL) has developed an optical measurement tool for parabolic solar collectors that measures the combined errors due to absorber misalignment and reflector slope error. The combined absorber alignment and reflector slope errors are measured using a digital camera to photograph the reflected image of the absorber in the collector. Previous work using the image of the reflection of the absorber finds the reflector slope errors from the reflection of the absorber and an independent measurement of the absorber location. The accuracy of the reflector slope error measurement is thus dependent on the accuracy of the absorber location measurement. By measuring the combined reflector-absorber errors, the uncertainty in the absorber location measurement is eliminated. The related performance merit, the intercept factor, depends on the combined effects of the absorber alignment and reflector slope errors. Measuring the combined effect provides a simpler measurement and a more accurate input to the intercept factor estimate. The minimal equipment and setup required for this measurement technique make it ideal for field measurements.

Stynes, J. K.; Ihas, B.

2012-04-01

214

High-Order FEM Formulation for 3-D Slope Instability  

Directory of Open Access Journals (Sweden)

Full Text Available High-order finite element method (FEM formulation also referred to as spectral element method (SEM formulation is currently implemented in this paper for 3-dimensional (3-D elasto-plastic problems in stability assessment of large- scale slopes (vegetated and barren slopes in different instability conditions such as seismic and saturation. We have reviewed the SEM formulation, and have sought its applicability for vegetated slopes. Utilizing p (high-order polynomial degree or spectral degrees and h (mesh operation for quality meshing in required elemental budgets refining techniques in the existing FEM, the complexity of problem domain can be well addressed in greater numerical stability. Unlike the existing FEM formulation, this high-order FEM employs the same integration and interpolation points to achieve a progressive response of the instability, which drastically reduces the computational costs (formation of diagonalized mass matrix and offers significant benefits to slope instability computations for serial and parallel implementations. With this formulation, we have achieved the following three qualities in slope instability modeling: 1 geometric flexibility of the finite elements, 2 high computational efficiency, and 3 reliable spectral accuracy. A sample problem has also been presented in this paper, which has accommodated all aforesaid numerical qualities.

Yatabe Ryuichi

2013-05-01

215

Infinite slope stability under steady unsaturated seepage conditions  

Science.gov (United States)

[1] We present a generalized framework for the stability of infinite slopes under steady unsaturated seepage conditions. The analytical framework allows the water table to be located at any depth below the ground surface and variation of soil suction and moisture content above the water table under steady infiltration conditions. The framework also explicitly considers the effect of weathering and porosity increase near the ground surface on changes in the friction angle of the soil. The factor of safety is conceptualized as a function of the depth within the vadose zone and can be reduced to the classical analytical solution for subaerial infinite slopes in the saturated zone. Slope stability analyses with hypothetical sandy and silty soils are conducted to illustrate the effectiveness of the framework. These analyses indicate that for hillslopes of both sandy and silty soils, failure can occur above the water table under steady infiltration conditions, which is consistent with some field observations that cannot be predicted by the classical infinite slope theory. A case study of shallow slope failures of sandy colluvium on steep coastal hillslopes near Seattle, Washington, is presented to examine the predictive utility of the proposed framework. Copyright 2008 by the American Geophysical Union.

Lu, N.; Godt, J.

2008-01-01

216

Slope hummock development, Fosheim Peninsula, Ellesmere Island, Nunavut, Canada  

Science.gov (United States)

Slope hummocks, a type of nonsorted patterned ground, are composed of stratified, organic, silty sand, and develop through the interaction of niveo-eolian deposition, solifluction, slopewash, and vegetation growth. Fields of hummocks show consistent patterns: forms on convex slopes increase in height downslope until the channel is reached, whereas those on convexo-concave slopes increase on the upper convexity but are buried by niveo-eolian deposition downslope of the snowbank remnant. These trends can be reproduced using a simple numerical model based on measured slope and snow depth profiles, sediment concentrations in the snow and solifluction rates. The model indicates that hummocks transit slopes of 20-40 m in about 2-4 ka, a time-frame that is plausible given site emergence, measured rates of solifluction, and published dates for organic horizons within hummocks on northern Ellesmere Island. Sensitivity analyses show that long-term effect of climate warming on hummock heights may differ depending on whether it is accompanied by precipitation increase or decrease. The required combination of two-sided freezing to promote plug-like movement, incomplete vegetation cover and thin snow that enable eolian erosion during winter and spring, and vegetation growth in snow-bed sites to stabilize niveo-eolian deposits may explain why these forms are important regionally but apparently are not present throughout the Arctic.

Lewkowicz, Antoni G.

2011-03-01

217

Kinetics of crimp and slope grip in rock climbing.  

Science.gov (United States)

The aim was to investigate differences of the kinetics of the crimp and the slope grip used in rock climbing. Nine cadaver fingers were prepared and fixated with the proximal phalanx in a frame. The superficial (FDS) and deep (FDP) flexor tendons were loaded selectively and together with 40 N in the crimp grip (PIP joint flexed 90°/DIP joint hyperextended) and the slope grip position (<25° flexed/50° flexed respectively). Five different grip sizes were tested and the flexion force which was generated to the grip was measured. In the crimp grip the FDP generated more flexion force in small sized holds whereas the FDS generated more force in the larger holds. During the slope grip the FDP was more effective than the FDS. While both tendons were loaded, the flexion force was always greater during crimp grip compared with the slope grip. The FDP seems to be most important for very small holds using the crimp grip but also during slope grip holds whereas the FDS is more important for larger flat holds. PMID:21576719

Schweizer, Andreas; Hudek, Robert

2011-05-01

218

Slope Stability Analysis of Itakpe Iron Ore Mine, Itakpe, Nigeria  

Directory of Open Access Journals (Sweden)

Full Text Available The slope stability of the Itakpe Iron Ore Mine has been carried out using computer software, ROCKPACK III. One hundred and twenty three dip and dip direction values were obtained using compass clinometer. The Itakpe Iron Ore Mine was divided into four benches; 241 - 258 m, 263 - 275 m, 276 - 286 m and 308 - 312 m. Joints along the discontinuities were mapped. The data obtained were analyzed using ROCKPACK III. The results indicate that the discontinuities within the critical zone are potentially unstable and can lead to planar failure. The Markland test carried out for wedge failure indicates that the intersection of the discontinuities does not fall within the critical zone hence there cannot be any wedge failure of the slope within the level 241 - 258 m. The presence of discontinuities that plot within the toppling critical zone indicates that there is potential toppling failure on the slope at the 276 - 286 m level. In addition, the toppling failure test shows the absence of discontinuities that plot within the toppling critical zone and this indicates the absence of poten-tial toppling failure of the slope at the 308 - 312 m level. The result of the study will be useful to the man-agement of the Itakpe iron ore mine in having a proper understanding of the failure mechanism of the slopes.

Jide Muili Akande

2011-06-01

219

After the slippery slope: Dutch experiences on regulating active euthanasia.  

Science.gov (United States)

"When a country legalizes active euthanasia, it puts itself on a slippery slope from where it may well go further downward." If true, this is a forceful argument in the battle of those who try to prevent euthanasia from becoming legal. The force of any slippery slope argument, however, is by definition limited by its reference to future developments which cannot empirically be sustained. Experience in the Netherlands--where a law regulating active euthanasia was accepted in April 2001--may shed light on the strengths as well as the weaknesses of the slippery slope argument in the context of the euthanasia debate. This paper consists of three parts. First, it clarifies the Dutch legislation on euthanasia and explains the cultural context in which it originated. Second, it looks at the argument of the slippery slope. A logical and an empirical version are distinguished, and the latter, though philosophically less interesting, proves to be most relevant in the discussion on euthanasia. Thirdly, it addresses the question whether Dutch experiences in the process of legalizing euthanasia justify the fear of the slippery slope. The conclusion is that Dutch experiences justify some caution. PMID:16175719

Boer, Theo A

2003-01-01

220

Slope measurement of bent plates using double grating shearing interferometry  

Energy Technology Data Exchange (ETDEWEB)

A grating-based shearing interferometeric setup for slope measurement of bent plates has been proposed. The specimen under test is illuminated by a collimated beam from the laser. Light reflected from the specimen passes through two identical holographic gratings placed in tandem. The grating frequency has been so chosen that the diffracted orders from each grating are separated out distinctly. Two first-order beams diffracted from each of the gratings superpose in space. In the resulting interferogram, the fringes due to slope information of the object are visualized. Mathematical formulation for experimental determination of slope values has been undertaken. Validation of the experimental results with theoretical predictions in case of cantilever beam provides good correlation. The main advantage of the technique has been the realization of very compact geometry without the need for spatial filtering arrangement commonly associated with the grating-based techniques used to date.

Dhanotia, Jitendra; Prakash, Shashi; Rana, Santosh; Sasaki, Osami

2011-06-20

 
 
 
 
221

Development of a new generation of optical slope measuring profiler  

Energy Technology Data Exchange (ETDEWEB)

A collaboration, including all DOE synchrotron labs, industrial vendors of x-ray optics, and with active participation of the HBZ-BESSY-II optics group has been established to work together on a new slope measuring profiler -- the optical slope measuring system (OSMS). The slope measurement accuracy of the instrument is expected to be<50 nrad for the current and future metrology of x-ray optics for the next generation of light sources. The goals were to solidify a design that meets the needs of mirror specifications and also be affordable; and to create a common specification for fabrication of a multi-functional translation/scanning (MFTS) system for the OSMS. This was accomplished by two collaborative meetings at the ALS (March 26, 2010) and at the APS (May 6, 2010).

Yashchuk, Valeriy V.; Takacs, Peter Z.; McKinney, Wayne R.; Assoufid, Lahsen; Siewert, Frank; Zeschke, Thomas

2010-09-16

222

Slope One Predictors for Online Rating-Based Collaborative Filtering  

CERN Document Server

Rating-based collaborative filtering is the process of predicting how a user would rate a given item from other user ratings. We propose three related slope one schemes with predictors of the form f(x) = x + b, which precompute the average difference between the ratings of one item and another for users who rated both. Slope one algorithms are easy to implement, efficient to query, reasonably accurate, and they support both online queries and dynamic updates, which makes them good candidates for real-world systems. The basic slope one scheme is suggested as a new reference scheme for collaborative filtering. By factoring in items that a user liked separately from items that a user disliked, we achieve results competitive with slower memory-based schemes over the standard benchmark EachMovie and Movielens data sets while better fulfilling the desiderata of CF applications.

Lemire, D; Lemire, Daniel; Maclachlan, Anna

2007-01-01

223

Forest harvesting influence on slope erosion in Baikal Basin Mountains  

Science.gov (United States)

Post-logging recovery of forest water protection and erosion prevention functions can occur different ways on slopes and in big river catchments. While erosion decreases several times during only three to five years after logging on slopes, as compared to its immediate post-logging rate, water silt load in big rivers can remain high for decades after forest logging in their catchments. Among other factors, this can be attributable to erosion of timber transportation roads and skidding trails, which become extremely eroded 10-15 years following forest logging. One should not underestimate a probable sediment load increase resulting from post-logging channel runoff changes. Disregarding this increase leads to contradictory conclusions about post-logging recovery of forest water protecting capability. Investigating this issue requires to clearly determine the type of the forest site of interest (a certain slope, an elementary or a complex catchments) and to consider the experience gained so far in estimating erosion rate changes depending on changing forest areas of continents. Therefore, hierarchical river catchments ranking should be recognized effective and useful for forest hydrology. This approach will allow systematizing the existing information and facilitating the development of fruitful analysis of water protection and erosion prevention functions of forest in areas of different ranks. This study used an approach that enabled a single-model description of the rate of soil erosion previously estimated by different models for areas of various ranks, from a micro slope to elementary catchments. An elementary catchments is defined as the smallest drainage area characterized by uniform surface, ground, and vegetation structures and having a single well-pronounced channel, with hydro network being practically absent. Using runoff slope length as the argument and introducing a dummy variable that describes specific investigation methodologies ensured high generality of this model. The model describing soil erosion rates on separate slopes and in elementary catchments is: ln M=-9,3+0,95lnX-0,064NlnL+0,069lnXlnm/lnL+5,03K+1,49lnI+ +0,0162ln((X-W)/In)i-0,00026ln((X-W)/In)i2 R2 =0,86; ?=1,04; F?=221; where M is sediment load module, t/km2; N is time since the last disturbance (fire or logging), years; X is precipitation amount, mm; I is precipitation rate, mm/min; m is soil mineralization level, %; L is length of slope where surface runoff occurs, m; W is forest floor moisture capacity, mm; In is soil water permeability, mm/min; i is slope, degrees; K is investigation methodology indicator (it is assumed to equal 1 in the case of area sprinkling and 2 in erosion observations on permanent runoff sample sites and in catchments); R² is multiple determination coefficient;?? is standard deviation, ton per km2; and F? is Fisher criterion. All coefficients are 95% confident. This model shows a monotonous increase in sediment load module with increasing total moisture in an area and soil mineralization on burned or harvested sites. This module decreases with increasing forest floor moisture capacity and soil water permeability. These trends, as well as slope-caused soil erosion changes, were reported by earlier studies. Our experimental data obtained by other methods did not impact the earlier identified relationships. Therefore, estimating slope length precipitation rate influences on sediment load and predicting soil erosion slowdown on disturbed sites present a great interest. Numerical experiments with this model showed the sediment load module to increase with increasing precipitation rate and to decrease with increasing slope length. This decrease might be attributable to soil particle re-deposition in the lower parts of a slope. Re-deposited erosion products do not get into streams and become involved again in soil development.

Onuchin, A. A.; Borisov, A. N.; Burenina, T. A.

2009-04-01

224

Development of a new generation of optical slope measuring profiler  

International Nuclear Information System (INIS)

A collaboration including all DOE synchrotron laboratories and industrial vendors of X-ray optics, and with active participation of the HBZ-BESSY-II optics group, has been established to work together on a new slope measuring profiler-the Optical Slope Measuring System (OSMS). The slope measurement accuracy of the instrument is expected to be <50 nrad for the current and future metrology of X-ray optics for the next generation of light sources. The goals were to solidify a design that meets the needs of mirror specifications and also be affordable, and to create a common specification for fabrication of a multi-functional translation/scanning (MFTS) system for the OSMS. This was accomplished by two collaborative meetings at the ALS (March 26, 2010) and at the APS (May 6, 2010).

2011-09-01

225

An Experimental Study of Submarine Canyon Evolution on Continental Slopes  

Science.gov (United States)

Submarine canyons define the morphology of many continental slopes and are conduits for the transport of sediment from shallow to deep water. Though the origin and evolution of submarine canyons is still debated, there is general agreement that sediment gravity flows play an important role. Here we present results from a simple, reduced-scale sandbox experiment designed to investigate how sediment gravity flows generate submarine canyons. In the experiments, gravity flows were modeled using either sediment-free or turbid saline currents. Unconfined flows were released onto an inclined bed of sand bounded on the downstream end by a movable floor that was incrementally lowered during the course of an experiment to produce an escarpment. This design was developed to represent the growth of relief across the continental slope. To monitor canyon evolution on the slope, we placed an overhead DSLR camera to record vivid time-lapse videos. At the end of each experimental stage we scanned the topography by imaging a series of submerged laser stripes, each projected from a motor-driven transverse laser sheet, onto a calibrated Cartesian coordinate system to produce high resolution bathymetry without draining the ambient water. In areas unaffected by the flows, we observe featureless, angle-of-repose submarine slopes formed by retrogressive breaching processes. In contrast, areas influenced by gravity flows cascading across the shelf break are deeply incised by submarine canyons with well-developed channel networks. Our results show that downslope gravity flows and submarine falling base level are both required to produce realistic canyon morphologies at laboratory scale. Though our mechanism for generating relief may be a rather crude analogue for the processes driving slope evolution, we hope our novel approach can stimulate new questions about the coevolution of canyons and slopes and motivate further experimental work to address them.

Lai, S. Y.; Gerber, T. P.; Amblas, D.

2013-12-01

226

Research on the seasonal snow of the Arctic Slope  

Energy Technology Data Exchange (ETDEWEB)

This project deals with the seasonal snow on Alaska's Arctic Slope. It is concentrated on snow of the R{sub 4}D project area. However, an important aspect of this study is to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

Benson, C.S.

1986-01-01

227

Research on the seasonal snow of the Arctic Slope  

Energy Technology Data Exchange (ETDEWEB)

This project deals with the seasonal snow on Alaska's Arctic Slope. Although it is concentrated on snow of the R{sub 4}D project area, it is important to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

Benson, C.S.

1991-01-01

228

Research on the seasonal snow of the Arctic Slope  

Energy Technology Data Exchange (ETDEWEB)

This project deals with the seasonal snow on Alaska's Arctic Slope. Although it is concentrated on snow of the R{sub 4}D project area, it is important to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

Benson, C.S.

1987-01-01

229

Research on the seasonal snow of the Arctic Slope  

Energy Technology Data Exchange (ETDEWEB)

This project deals with the seasonal snow on Alaska's Arctic Slope. Although it is concentrated on snow of the R40 project area, it is important to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination Of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover.

Benson, C.S.

1989-01-01

230

On the slope stratification of certain Shimura varieties  

CERN Multimedia

In this paper we study the slope stratification on the good reduction of the type C family Shimura varieties. We show that there is an open dense subset $U$ of the moduli space such that any point in $U$ can be deformed to a point with a given lower {\\it admissible} Newton polygon. For the Siegel moduli spaces, this is obtained by F. Oort which plays an important role in his proof of the strong Grothendieck conjecture concerning the slope stratification. We also investigate the $p$-divisible groups and their isogeny classes arising from the abelian varieties in question.

Yu, C F

2004-01-01

231

Wave forces on horizontal cylinder resting on sloping bottom  

Energy Technology Data Exchange (ETDEWEB)

Experiments have been carried out to determine the wave forces exerted on horizontal cylinder which are very close to bed in wave transformation zone. In the experimental condition, bottom slope was 1/10. Cnoidal wave theory was used to find out the near-bottom kinematics due to waves and the hydrodynamic wave forces. Since bottom slope is a very important effect on wave motion, wave forces depend on dimensionless local depth ratio (d/H). Experimental results with waves agree well with cnoidal wave solution.

Yuksel, Y. [Yildez Technical Univ. (Turkey); Narayanan, R. [UMIST, Manchester (United Kingdom)

1994-12-31

232

Using waste to reduce slope erosion on road embankments  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Urban waste may be used to reduce slope erosion of highway embankments. Whereas different kinds of compost have been tested in the USA for highway revegetation, sewage sludge has been used only for agricultural purposes. This paper presents the results of research carried out in order to study the viability of the application of sewage sludge compared with compost. Test areas measuring 4 m 3 5 m were constructed on a new highway embankment with 2 : 1 and 3 : 2 side slopes in the south of Spai...

On?a, Juan; Osorio, Francisco

2006-01-01

233

Hydrostatic pressure in slopes with a low permeability  

Energy Technology Data Exchange (ETDEWEB)

The effect of water on slopes depends on the permeability of the rock mass and its defects. In principle, low permeability benefits stability but the hydraulic parameter has an indirect effect on other geomechanical parameters: strength, roughness and internal stress. In slopes with a low permeability, it is difficult to develop an effective drainage system. For this reason, it is necessary to estimate hydrostatic pressure by calculation. This study was carried out at the Cervantes opencast coal site, Penarroya, Cordoba. 2 tabs., 9 refs., 6 figs.

Daza Sanchez, A.

1988-12-01

234

Aspects of slope stability in opencast coal mining  

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with methods of obtaining adequate slope stability data for open cast mines. Preliminary mine planning and geotechnical data collection are discussed. Shear strength measurements carried out on rocks from the Low Close opencast mine are described as are investigations into the effect of moisture on the compressive strength, tensile strength, scleroscope hardness and Schmidt rebound hardness of rock. The factors that need to be taken into account in opencast mine design in order to ensure stability and economical mining are highlighted. These include stripping ratio, cut face orientation, angle of slope and bench height.

Ojo, O.

1988-07-01

235

Red Beans and Rice: Slope failure experimental modeling  

Science.gov (United States)

In this activity, students replicate the slope failure experiment presented by Densmore et al. (1997) in the journal Science. They are given the original article and the slope failure apparatus (along with all associated materials) and then they need to figure out how to replicate the experiment. Once they have completed an experimental run of sufficient length, they compile and analyze their data and compare it to the article's results. After completing this portion of the lab, the students read the discussion and reply (Aalto et al., 1998; Densmore et al., 1998) and critically evaluate they results of the experiment and its applicability to the real world and landscape evolution.

Hickson, Tom

236

Mechanical Properties of Human Fetal Talus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mechanical characterization of human cartilage anlagen is required to effectively model congenital musculoskeletal deformities. Such modeling can effectively explore the effect of treatment procedures and potentially suggest enhanced treatment methods. Using serial MRI, we have noted shape changes of the cartilaginous hindfoot anlagen in patients with clubfoot, suggesting they are soft and deformable. We therefore determined the stress relaxation behavior of cartilage plugs obtained from thir...

Mahmoodian, Roza; Leasure, Jeremi; Gadikota, Hemanth; Capaldi, Franco; Siegler, Sorin

2009-01-01

237

Application of Grey Theory and Wavelet Neural Network in Slope Displacements Prediction  

Directory of Open Access Journals (Sweden)

Full Text Available Slope displacement is the external performance of slope stability, predicting slope displacement according to the original displacement monitoring data and predicting slope stability, which can effectively prevent the occurrence of landslide disaster. Slope displacement can be regard as the sum of trend item and random item, grey system G (1, 1 model can simulate the trend of the slope displacement time series and the wavelet neural network can predict the random variations of slope displacement. Based on the grey-wavelet neural network algorithm, prediction analysis of displacement was carried, the displacement prediction of Changchun west railway station foundation pit verify the accuracy and practicability of this method.

Jiang Ping

2013-01-01

238

The slope stability under underground mining of Anjialing open-pit mine on Pingshuo  

Energy Technology Data Exchange (ETDEWEB)

Using the Anjialing open-pit mine in Pingshuo for research, limit equilibrium theory and geo-slope software for slope stability analysis were used to consider the influence of the external environment such as ground water and underground mining on slope stability. The study included studying water pressure and a slope damage model under underground mining, carrying out slope stability calculations and providing prevention and control measures. Results show that the water pressure and underground mining are the important factors affecting slope stability. Some upper slopes are seriously affected and sliding is possible. 9 refs., 5 figs., 2 tabs.

Chen Shi-kuo; Yang Tian-hong; Zhang Hua-xing [Northeastern University, Shenyang (China). Center for Rock Instability and Seismic Research

2008-02-15

239

THE SLOPE OF THE BARYONIC TULLY-FISHER RELATION  

International Nuclear Information System (INIS)

We present the results of a baryonic Tully-Fisher relation (BTFR) study for a local sample of relatively isolated disk galaxies. We derive a BTFR with a slope near 3 measured over about 4 dex in baryon mass for our combined H I and bright spiral disk samples. This BTFR is significantly flatter and has less scatter than the TFR (stellar mass only) with its slope near 4 reported for other samples and studies. A BTFR slope near 3 is in better agreement with the expected slope from simple ?CDM cosmological simulations that include both stellar and gas baryons. The scatter in the TFR/BTFR appears to depend on W20: galaxies that rotate slower have more scatter. The atomic gas-to-stars ratio shows a break near W20 = 250 km s-1 probably associated with a change in star formation efficiency. In contrast, the absence of such a break in the BTFR suggests that this relation was probably set at the main epoch of baryon dissipation rather than as a product of later galactic evolution.

2010-09-01

240

How the spatial variation of tree roots affects slope stability  

Science.gov (United States)

It is now widely recognized that plant roots can reinforce soil against shallow mass movement. Although studies on the interactions between vegetation and slope stability have significantly augmented in recent years, a clear understanding of the spatial dynamics of root reinforcement (through additional cohesion by roots) in subalpine forest is still limited, especially with regard to the roles of different forest management strategies or ecological landscapes. The architecture of root systems is important for soil cohesion, but in reality it is not possible to measure the orientation of each root in a system. Therefore, knowledge on the effect of root orientation and anisotropy on root cohesion on the basis of in situ data is scanty. To determine the effect of root orientation in root cohesion models, we investigated root anisotropy in two mixed, mature, naturally regenerated, subalpine forests of Norway spruce (Picea abies), and Silver fir (Abies alba). Trees were clustered into islands, with open spaces between each group, resulting in strong mosaic heterogeneity within the forest stand. Trenches within and between clusters of trees were dug and root distribution was measured in three dimensions. We then simulated the influence of different values for a root anisotropy correction factor in forests with different ecological structures and soil depths. Using these data, we have carried out simulations of slope stability by calculating the slope factor of safety depending on stand structure. Results should enable us to better estimate the risk of shallow slope failure depending on the type of forest and species.

Mao, Zhun; Stokes, A.; Jourdan, C.; Rey, H.; Courbaud, B.; Saint-André, L.

2010-05-01

 
 
 
 
241

Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters  

Energy Technology Data Exchange (ETDEWEB)

Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.

Sherwood, O; Edinger, E; Guilderson, T P; Ghaleb, B; Risk, M J; Scott, D B

2008-08-15

242

Optimization of a Wall Built on a Slope  

Directory of Open Access Journals (Sweden)

Full Text Available This project focuses on optimizing the construction of a wall with identical segments built on a slope. Faced with certain variable and fixed cost limitations, one can find the width of a segment that will minimize the total production cost. In this case, the lowest total cost comes from using 10 segments of width 3m.

John Hanna

2011-01-01

243

The Snowmass Points and Slopes Benchmarks for SUSY Searches  

CERN Multimedia

The ``Snowmass Points and Slopes'' (SPS) are a set of benchmark points and parameter lines in the MSSM parameter space corresponding to different scenarios in the search for Supersymmetry at present and future experiments. This set of benchmarks was agreed upon at the 2001 ``Snowmass Workshop on the Future of Particle Physics'' as a consensus based on different existing proposals.

Allanach, Benjamin C; Blair, G A; Carena, M S; de Roeck, A; Dedes, A; Djouadi, Abdelhak; Gerdes, D W; Ghodbane, N; Gunion, J F; Haber, Howard E; Han, T; Heinemeyer, S; Hewett, J L; Hinchliffe, Ian; Kalinowski, Jan; Logan, H E; Martin, S P; Martyn, H U; Matchev, K T; Moretti, S; Moortgat, F; Moortgat-Pick, G; Mrenna, S; Nauenberg, U; Okada, Y; Olive, Keith A; Porod, Werner; Schmitt, M; Su, S; Wagner, C E M; Weiglein, Georg; Wells, J; Wilson, G W; Zerwas, Peter M

2002-01-01

244

Slope stability assessment for historical monument management, Machu Picchu, Peru.  

Czech Academy of Sciences Publication Activity Database

. Zittau : DGGT, 2009. s. 413.[Conference on Engineering Geology and Forum Young Engineering Geologists /17./. 07.05.2009-10.05.2009, Zittau]Grant CEP: GA ?R GP205/09/P383Výzkumný zám?r: CEZ:AV0Z30460519Klí?ová slova: slope stabilityKód oboru RIV: DB - Geologie a mineralogie

Klimeš, Jan

245

Slope histogram distribution-based parametrisation of Martian geomorphic features  

Science.gov (United States)

The application of geomorphometric methods on the large Martian digital topographic datasets paves the way to analyse the Martian areomorphic processes in more detail. One of the numerous methods is the analysis is to analyse local slope distributions. To this implementation a visualization program code was developed that allows to calculate the local slope histograms and to compare them based on Kolmogorov distance criterion. As input data we used the digital elevation models (DTMs) derived from HRSC high-resolution stereo camera image from various Martian regions. The Kolmogorov-criterion based discrimination produces classes of slope histograms that displayed using coloration obtaining an image map. In this image map the distribution can be visualized by their different colours representing the various classes. Our goal is to create a local slope histogram based classification for large Martian areas in order to obtain information about general morphological characteristics of the region. This is a contribution of the TMIS.ascrea project, financed by the Austrian Research Promotion Agency (FFG). The present research is partly realized in the frames of TÁMOP 4.2.4.A/2-11-1-2012-0001 high priority "National Excellence Program - Elaborating and Operating an Inland Student and Researcher Personal Support System convergence program" project's scholarship support, using Hungarian state and European Union funds and cofinances from the European Social Fund.

Balint, Zita; Székely, Balázs; Kovács, Gábor

2014-05-01

246

Recurring Slope Lineae and Future Exploration of Mars  

Science.gov (United States)

Recurring slope lineae (RSL) on Mars may be evidence for the seasonal flow or seepage of water on relatively warm slopes. RSL are narrow (seasons over low-albedo surfaces, fade when inactive, and recur over multiple Mars years [McEwen et al., 2011, Science]. RSL often follow small gullies, but no topographic changes have been detected via 30 cm/pixel images from HiRISE on MRO. The fans on which RSL terminate have distinctive color and spectral properties in MRO/CRISM, but lack distinctive water absorption bands [Ojha et al., 2013, GRL]. The first group of confirmed RSL appear and lengthen in the late southern spring through summer from 48° - 32°S latitude, favoring equator-facing slopes—times and places with peak surface temperatures ranging from >250 K to >300 K. Over the past Martian year we have monitored active RSL in equatorial (0°-15°S) regions of Mars, especially in the deep canyons of Valles Marineris [McEwen et al., 2014, Nature Geoscience]. These equatorial RSL are especially active on north-facing slopes in northern summer and spring and on south-facing slopes in southern spring and summer, following the most normal solar incidence angles on these steep slopes. More recently we have confirmed RSL near 35°N in the low-albedo and low-altitude Acidalia Planitia. All RSL locations have warm peak daily temperatures (typically >273 K at the surface) in the seasons when RSL are active, and occur on steep, rocky, low-albedo slopes. However, most times and places with these properties lack apparent RSL, so there are additional, unseen requirements. We do not know what time of day RSL are actively flowing. Seasonal variation in the atmospheric column abundance of water vapor does not match the RSL activity. Seasonal melting of shallow ice best explains the RSL observations, but the origin and replenishment of such ice is not understood, especially in the tropics. Laboratory experiments are consistent with two key MRO observations: (1) that seeping water darkens basaltic soils but may only produce weak water absorption bands undetectable in ratio spectra after partial dehydration during the low-humidity middle afternoon conditions when MRO observes; and (2) the flows are more linear than under terrestrial conditions and do not erode channels under Martian atmospheric pressures [Masse et al., 2014, LPSC]. No dry process is known to create such slowly creeping seasonal flows. The potential for equatorial water activity creates new exploration opportunities, to search for extant life, as well as challenges such as the definition of special regions for planetary protection.

McEwen, Alfred; Byrne, Shane; Chevrier, Vincent; Chojnacki, Matt; Dundas, Colin; Masse, Marion; Mattson, Sarah; Ojha, Lujendra; Pommerol, Antoine; Toigo, Anthony; Wray, James

2014-05-01

247

Consequence assessment of large rock slope failures in Norway  

Science.gov (United States)

Steep glacially carved valleys and fjords in Norway are prone to many landslide types, including large rockslides, rockfalls, and debris flows. Large rockslides and their secondary effects (rockslide-triggered displacement waves, inundation behind landslide dams and outburst floods from failure of landslide dams) pose a significant hazard to the population living in the valleys and along the fjords shoreline. The Geological Survey of Norway performs systematic mapping of unstable rock slopes in Norway and has detected more than 230 unstable slopes with significant postglacial deformation. This large number necessitates prioritisation of follow-up activities, such as more detailed investigations, periodic displacement measurements, continuous monitoring and early-warning systems. Prioritisation is achieved through a hazard and risk classification system, which has been developed by a panel of international and Norwegian experts (www.ngu.no/en-gb/hm/Publications/Reports/2012/2012-029). The risk classification system combines a qualitative hazard assessment with a consequences assessment focusing on potential life losses. The hazard assessment is based on a series of nine geomorphological, engineering geological and structural criteria, as well as displacement rates, past events and other signs of activity. We present a method for consequence assessment comprising four main steps: 1. computation of the volume of the unstable rock slope; 2. run-out assessment based on the volume-dependent angle of reach (Fahrböschung) or detailed numerical run-out modelling; 3. assessment of possible displacement wave propagation and run-up based on empirical relations or modelling in 2D or 3D; and 4. estimation of the number of persons exposed to rock avalanches or displacement waves. Volume computation of an unstable rock slope is based on the sloping local base level technique, which uses a digital elevation model to create a second-order curved surface between the mapped extent of the unstable rock slope. This surface represents the possible basal sliding surface of an unstable rock slope. The elevation difference between this surface and the topographic surface estimates the volume of the unstable rock slope. A tool has been developed for the present study to adapt the curvature parameters of the computed surface to local geological and structural conditions. The obtained volume is then used to define the angle of reach of a possible rock avalanche from the unstable rock slope by using empirical derived values of angle of reach vs. volume relations. Run-out area is calculated using FlowR; the software is widely used for run-out assessment of debris flows and is adapted here for assessment of rock avalanches, including their potential to ascend opposing slopes. Under certain conditions, more sophisticated and complex numerical run-out models are also used. For rock avalanches with potential to reach a fjord or a lake the propagation and run-up area of triggered displacement waves is assessed. Empirical relations of wave run-up height as a function of rock avalanche volume and distance from impact location are derived from a national and international inventory of landslide-triggered displacement waves. These empirical relations are used in first-level hazard assessment and where necessary, followed by 2D or 3D displacement wave modelling. Finally, the population exposed in the rock avalanche run-out area and in the run-up area of a possible displacement wave is assessed taking into account different population groups: inhabitants, persons in critical infrastructure (hospitals and other emergency services), persons in schools and kindergartens, persons at work or in shops, tourists, persons on ferries and so on. Exposure levels are defined for each population group and vulnerability values are set for the rock avalanche run-out area (100%) and the run-up area of a possible displacement wave (70%). Finally, the total number of persons within the hazard area is calculated taking into account exposure and vulnerability. The method for conse

Oppikofer, Thierry; Hermanns, Reginald L.; Horton, Pascal; Sandøy, Gro; Roberts, Nicholas J.; Jaboyedoff, Michel; Böhme, Martina; Yugsi Molina, Freddy X.

2014-05-01

248

Evaluation of depolarization changes during acute myocardial ischemia by analysis of QRS slopes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

OBJECTIVE: This study evaluates depolarization changes in acute myocardial ischemia by analysis of QRS slopes. METHODS: In 38 patients undergoing elective percutaneous coronary intervention, changes in upward slope between Q and R waves and downward slope between R and S waves (DS) were analyzed. In leads V1 to V3, upward slope of the S wave was additionally analyzed. Ischemia was quantified by myocardial scintigraphy. Also, conventional QRS and ST measures were determined. RESULTS: QRS slope...

Ringborn, Michael; Romero, Daniel; Pueyo, Esther; Pahlm, Olle; Wagner, Galen S.; Laguna, Pablo; Platonov, Pyotr

2011-01-01

249

Distribution of solar radiation including slope effect in South Korea  

Science.gov (United States)

Agriculture and ecosystems are very solar radiation-sensitive making them useful for monitoring the impact on future food production. Accurate solar radiation data are necessary to evaluate major physiological reaction of crops and an impact of climate change. For most upland crops and orchard plants growing in sloping terrain, however the meteorological data are often limited. Considering the scarcity of detailed meteorological data around the country, there is a need for methods which can estimate reference solar radiation with limited data. This study describes a method to estimate monthly average daily solar radiation of considering the slope distribution. It was calculated using the 2010's meteorological data and KT method which is entered DEM and spatial interpolation data of both monthly average daily extraterrestrial radiation and monthly average daily radiation on land surface. Extracted slope from the DEM in South Korea include range between 0? to 77? and most of the land is mountainous. According to the slope, solar radiation characteristic show to have high value in spring season (April) relatively other season. Summer season interrupt to reach direct solar radiation, cause is unstable atmospheric and cloud. The distributions of monthly accumulated solar radiation indicated that differences caused by the topography effect are more important in winter than in other season because of the dependency on the solar altitude angle and duration of sunshine. Result of KT method is confirmed to overestimate monthly average 1.38MJ?m􀬶?day than solar radiation weather station measurement values. Solar radiation of slope error value will need continuous research and correction through both fields survey and topography factor.

Baek, Shin Chul; Park, Jong-Hwa; Na, Sang Il; Park, Jin-Ki

2012-10-01

250

Cooperative Three-Robot System for Traversing Steep Slopes  

Science.gov (United States)

Teamed Robots for Exploration and Science in Steep Areas (TRESSA) is a system of three autonomous mobile robots that cooperate with each other to enable scientific exploration of steep terrain (slope angles up to 90 ). Originally intended for use in exploring steep slopes on Mars that are not accessible to lone wheeled robots (Mars Exploration Rovers), TRESSA and systems like TRESSA could also be used on Earth for performing rescues on steep slopes and for exploring steep slopes that are too remote or too dangerous to be explored by humans. TRESSA is modeled on safe human climbing of steep slopes, two key features of which are teamwork and safety tethers. Two of the autonomous robots, denoted Anchorbots, remain at the top of a slope; the third robot, denoted the Cliffbot, traverses the slope. The Cliffbot drives over the cliff edge supported by tethers, which are payed out from the Anchorbots (see figure). The Anchorbots autonomously control the tension in the tethers to counter the gravitational force on the Cliffbot. The tethers are payed out and reeled in as needed, keeping the body of the Cliffbot oriented approximately parallel to the local terrain surface and preventing wheel slip by controlling the speed of descent or ascent, thereby enabling the Cliffbot to drive freely up, down, or across the slope. Due to the interactive nature of the three-robot system, the robots must be very tightly coupled. To provide for this tight coupling, the TRESSA software architecture is built on a combination of (1) the multi-robot layered behavior-coordination architecture reported in "An Architecture for Controlling Multiple Robots" (NPO-30345), NASA Tech Briefs, Vol. 28, No. 10 (October 2004), page 65, and (2) the real-time control architecture reported in "Robot Electronics Architecture" (NPO-41784), NASA Tech Briefs, Vol. 32, No. 1 (January 2008), page 28. The combination architecture makes it possible to keep the three robots synchronized and coordinated, to use data from all three robots for decision- making at each step, and to control the physical connections among the robots. In addition, TRESSA (as in prior systems that have utilized this architecture) , incorporates a capability for deterministic response to unanticipated situations from yet another architecture reported in Control Architecture for Robotic Agent Command and Sensing (NPO-43635), NASA Tech Briefs, Vol. 32, No. 10 (October 2008), page 40. Tether tension control is a major consideration in the design and operation of TRESSA. Tension is measured by force sensors connected to each tether at the Cliffbot. The direction of the tension (both azimuth and elevation) is also measured. The tension controller combines a controller to counter gravitational force and an optional velocity controller that anticipates the motion of the Cliffbot. The gravity controller estimates the slope angle from the inclination of the tethers. This angle and the weight of the Cliffbot determine the total tension needed to counteract the weight of the Cliffbot. The total needed tension is broken into components for each Anchorbot. The difference between this needed tension and the tension measured at the Cliffbot constitutes an error signal that is provided to the gravity controller. The velocity controller computes the tether speed needed to produce the desired motion of the Cliffbot. Another major consideration in the design and operation of TRESSA is detection of faults. Each robot in the TRESSA system monitors its own performance and the performance of its teammates in order to detect any system faults and prevent unsafe conditions. At startup, communication links are tested and if any robot is not communicating, the system refuses to execute any motion commands. Prior to motion, the Anchorbots attempt to set tensions in the tethers at optimal levels for counteracting the weight of the Cliffbot; if either Anchorbot fails to reach its optimal tension level within a specified time, it sends message to the other robots and the commanded motion is not executed. If any

Stroupe, Ashley; Huntsberger, Terrance; Aghazarian, Hrand; Younse, Paulo; Garrett, Michael

2009-01-01

251

Natural dam failure in the eastern slope of the Central Andes of Argentina. Numerical modelling of the 2005 Santa Cruz river outburst flood  

Science.gov (United States)

In the Central Andes of Argentina, ephemeral river blockage due to landslides deposition are common phenomena. During the first fortnight of January 2005, 11.5 * 106m3 of rock collapsed from the east slope of the Santa Cruz valley (San Juan province, Argentina). The rock mass displaced from 4300 m a.s.l., down to the valley bottom, at 2900 m a.s.l., and ran up the opposite flank of the valley. This produced the blockage of the Santa Cruz river and generated the Los Erizos lake. The rapid snow melting during the spring season caused the increase of the water level of the reservoir, leading to a process of overtopping on November 12th of 2005. 30 * 106m3 of water were released from the reservoir and the consequent outburst flood displaced along 250 km. From local reports of arrival times, we estimated that the outburst flood reduced its velocity from around 40 km/h near the source area to 6 km/h in its distal section. A road, bridges, and a mining post where destroyed. 75 tourists had to be rescued from the mountains using helicopters, and people from two localities had to be evacuated. Near its distal part, the flood damaged the facilities of the Caracoles power dam, which was under construction, and its inauguration had to be delayed one year due to the damage. The outburst flood produced changes in the morphology of the valley floor along almost all its path (erosion of alluvial fans, talus and terraces, and deposition of boulders). The most significant changes occurred in the first 70 km, especially upstream narrow sections, showing the importance of the backwater effects due to hydraulic ponding. In this work we carried out numerical simulations to obtain the velocity patterns of the flood, and compared them with those obtained from local reports. Furthermore, we analyze the relationship between the dynamics of the flood with the patterns of erosion and deposition near the source area.

Penna, I.; Daicz, S.; Zlotnik, S.; Derron, M.-H.; Jaboyedoff, M.

2012-04-01

252

Surface Slope Metrology on Deformable Soft X-ray Mirrors  

International Nuclear Information System (INIS)

We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situ visible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

2009-10-02

253

Surface Slope Metrology on Deformable Soft X-ray Mirrors  

International Nuclear Information System (INIS)

We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situvisible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

2009-10-02

254

Focus sensor with integrated high-range slope measurement  

International Nuclear Information System (INIS)

Focus sensors and deflectometric sensors find widespread application in optical testing, especially where a large measurement range is required as in plastics or free-form optics. This note describes the design of a combined sensor for the simultaneous measurement of the height and the local slope of a surface under test in one single measurement spot. The opto-mechanical set-up and the metrological characteristics are described in detail and the benefits of the integrated measurement are stated, e.g. for the correction of the slope- dependent signal of the focus distance signal or the enhanced characterization of optical surfaces. First measurement results on a spherical micro mirror array are shown. (technical design note)

2009-11-01

255

Breaking of Waves over a Steep Bottom Slope  

DEFF Research Database (Denmark)

The thesis deals with the wave breaking process of waves propagating over a steep submerged bottom slope. The amount of energy dissipated in the wave breaking process is focused upon. An extensive number of experimental tests (>400) using regular and irregular waves breaking over a simulated reef in the hydraulic laboratory are performed. Based on the experimental tests several formulae developed. Formulae are capable of predicting the transmitted wave height and wave energy flux, respectively. Furthermore, a numerical wave model based on the extended Mild-Slope equation has been developed. The model is capable of generating progressive irregular waves. Wave breaking has been included using a modification of the Battjes and Janssen [1978] periodic bore approach. The results from this study be applicable in the design of coastal structures as submerged breakwaters or artificial reefs.

Jensen, Morten S.

2004-01-01

256

Size effects of slope dynamics in a 2-dimensional sandpile  

Science.gov (United States)

We study a two-dimensional sandpile automaton model under the so-called critical slope dynamics where the stability depends upon the first derivative of the sand height, i.e. height difference. For fixed critical slope we investigate systems of increasing linear dimension L on the square lattice for both randomly and systematically built piles. Statistics are presented for the size and duration of the avalanches produced. For excess grains distributed with equal probability to nearest neighbours, the average cluster size tends to a fixed limit which is dependent on the size of the initial perturbation. Furthermore, stable behaviour appears to be reached for relatively low values of the linear dimension L ? 250. The average time taken for avalanches of all sizes to die away stabilizes less readily within the system sizes considered. No evidence is found in support of a scaling law of the usual type.

Ruskin, H. J.; McCarren, A. L.

1994-06-01

257

Surface Slope Metrology on Deformable Soft X-ray Mirrors  

Energy Technology Data Exchange (ETDEWEB)

We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situvisible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

Yuan, S.; Yashchuk, V.V.; Goldberg, K.A.; Celestre, R.; Church, M.; McKinney, W.R.; Morrison, G.; Warwick, T.

2009-09-18

258

Surface Slope Metrology on Deformable Soft X-ray Mirrors  

Energy Technology Data Exchange (ETDEWEB)

We report on the current state of surface slope metrology on deformable mirrors for soft x-rays at the Advanced Light Source (ALS). While we are developing techniques for in situ at-wavelength tuning, we are refining methods of ex situ visible-light optical metrology to achieve sub-100-nrad accuracy. This paper reports on laboratory studies, measurements and tuning of a deformable test-KB mirror prior to its use. The test mirror was bent to a much different optical configuration than its original design, achieving a 0.38 micro-radian residual slope error. Modeling shows that in some cases, by including the image conjugate distance as an additional free parameter in the alignment, along with the two force couples, fourth-order tangential shape errors (the so-called bird shape) can be reduced or eliminated.

Yuan, Sheng; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Celestre, Rich; Church, Matthew; McKinney, Wayne R.; Morrison, Greg; Warwick, Tony

2010-01-31

259

Desirable plant root traits for protecting unstable slopes against landslides  

Science.gov (United States)

A trait is defined as a distinct, quantitative property of organisms, usually measured at the individual level and used comparatively across species. Plant quantitative traits are extremely important for understanding the local ecology of any site. Plant height, architecture, root depth, wood density, leaf size and leaf nitrogen concentration control ecosystem processes and define habitat for other taxa. An engineer conjecturing as to how plant traits may directly influence physical processes occurring on sloping land just needs to consider how e.g. canopy architecture and litter properties influence the partitioning of rainfall among interception loss, infiltration and runoff. Plant traits not only influence abiotic processes occurring at a site, but also the habitat for animals and invertebrates. Depending on the goal of the landslide engineer, the immediate and long-term effects of plant traits in an environment must be considered if a site is to remain viable and ecologically successful. When vegetation is considered in models of slope stability, usually the only root parameters taken into consideration are tensile strength and root area ratio. Root system spatial structure is not considered, although the length, orientation and diameter of roots are recognized as being of importance. Thick roots act like soil nails on slopes, reinforcing soil in the same way that concrete is reinforced with steel rods. The spatial position of these thick roots also has an indirect effect on soil fixation in that the location of thin and fine roots will depend on the arrangement of thick roots. Thin and fine roots act in tension during failure on slopes and if they cross the slip surface, are largely responsible for reinforcing soil on slopes. Therefore, the most important trait to consider initially is rooting depth. To stabilize a slope against a shallow landslide, roots must cross the shear surface. The number and thickness of roots in this zone will therefore largely determine slope stability. Rooting depth is species dependent when soil conditions are not limiting and the number of horizontal lateral roots borne on the vertical roots usually changes with depth. Therefore, the number and orientation of roots that the shear surface intersects will change significantly with rooting depth for the same plant, even for magnitudes of only several cm. Similarly, depending on the geometry of the root system, the angle at which a root crosses the shear surface can also have an influence on its resistance to pullout and breakage. The angle at which a root emerges from the parent root is dependent on root type, depth and species (when soil conditions are not limiting). Due to the physiology of roots, a root branch can be initiated at any point along a parent root, but not necessarily emerge fully from the parent root. These traits, along with others including size, relative growth rate, regeneration strategies, wood structure and strength will be discussed with regard to their influence on slope stability. How each of these traits is influenced by soil conditions and plantation techniques is also of extreme importance to the landslide engineer. The presence of obstacles in the soil, as well as compaction, affects root length and branching pattern. Roots of many species of woody plants on shallow soils also tend to grow along fractures deep into the underlying bedrock which allows roots to locate supplies of nutrient and water rich pockets. Rooting depths of herbaceous species in water-limited environments are highly correlated with infiltration depth, but waterlogged soils can asphyxiate tree roots, resulting in shallow root systems. The need to understand and integrate each of these traits for a species is not easy. Therefore, we suggest a hierarchy whereby traits are considered in order of importance, along with how external factors influence their expression over time.

Stokes, A.; Atger, C.; Bengough, G.; Fourcaud, T.; Sidle, R. C.

2009-04-01

260

Seismic distress and slope instability of municipal solid waste landfills  

DEFF Research Database (Denmark)

The impact of seismic loading on municipal solid waste landfills is investigated numerically in the current study. Initially, the role of the main parameters involved in the linear or nonlinear dynamic response of landfills is determined in terms of developed inertial acceleration. The most important factors are the geometry, the waste material properties, and the characteristics of the seismic excitation. Concerning the evaluation of the potential failure mechanisms, the effect of the main parameters on the slope stability is underlined, and a comparison between circular slope instability and base sliding is presented. Furthermore, according to the failure envelopes adopted in the literature for the shear strength of the waste material, a decoupled procedure is utilized to estimate the developed landfill deformations. Finally, the generation of parasitic vertical acceleration (due to the multidimensional nature of the problem) is taken into account in stability assessment, while its effect on the resulting deformation is determined.

Zania, Varvara; Tsompanakis, Yiannis

2008-01-01

 
 
 
 
261

Bioengineering case studies sustainable stream bank and slope stabilization  

CERN Multimedia

This unique volume describes and evaluates 30 projects from across the United States where bio-stabilization was employed to address a detrimental naturally occurring process or byproduct of the built environment. Bio-stabilization (or soil bioengineering) refers to the use of plant materials, primarily live cuttings, arranged in the ground in different arrays to reinforce soils and protect upland slopes and/or stream banks against surficial erosion and shallow slope failures. Examples included in the collection represent different regions of the country and their specific conditions and challenges. Each project is illustrated with a number of distinctive photographs to support the reader's understanding and showcase the wide scope of projects and techniques presented. This book also: ·         Presents a range of well-documented case studies on key techniques and best practices for bio-stabilization projects ·         Emphasizes evaluation and comparison of different techniques and challeng...

Goldsmith, Wendi; McCullah, John

2014-01-01

262

HIGH FIELD Q-SLOPE AND THE BAKING EFFECT  

Energy Technology Data Exchange (ETDEWEB)

The performance of SRF cavities made of bulk Nb at high fields (peak surface magnetic field greater than about 90 mT) is characterized by exponentially increasing RF losses (high-field Q-slope), in the absence of field emission, which are often mitigated by a low temperature (100-140 °C, 12-48h) baking. In this contribution, recent experimental results and phenomenological models to explain this effect will be briefly reviewed. New experimental results on the high-field Q-slope will be presented for cavities that had been heat treated at high temperature in the presence of a small partial pressure of nitrogen. Improvement of the cavity performances have been obtained, while surface analysis measurements on Nb samples treated with the cavities revealed significantly lower hydrogen concentration than for samples that followed standard cavity treatments.

Ciovati, Gianluigi [JLAB

2009-11-01

263

Hydraulic Characteristics of a Stepped-slope Floating Breakwater  

International Nuclear Information System (INIS)

A stepped-slope floating breakwater is developed to provide wave protection to small ports and harbours. The width of the structure can be enhanced by increasing the number of breakwater units that are placed side-by-side to each other. This produces three types of test model, i.e. single-row, double-row and triple-row breakwaters. The test models have been tested in monochromatic waves in a wave flume to determine their hydraulic performance in various wave conditions. The incident and reflected wave profiles in the vicinity of the test models are recorded and analysed by using moving-probe method. The hydraulic performance of the test models are quantified by the coefficients of transmission, reflection and energy loss. The experimental results showed that the stepped-slope floating breakwater is an effective anti-reflection structure and a reasonably good wave attenuator.

2013-06-17

264

Quantitative laboratory observations of internal wave reflection on ascending slopes  

CERN Document Server

Internal waves propagate obliquely through a stratified fluid with an angle that is fixed with respect to gravity. Upon reflection on a sloping bed, striking phenomena are expected to occur close to the slope. We present here laboratory observations at moderately large Reynolds number. A particle image velocimetry (PIV) technique is used to provide time resolved velocity fields in large volumes. The generation of the second and third harmonic frequencies are clearly demonstrated in the impact zone. The mechanism for nonlinear wavelength selection is also discussed. Evanescent waves with frequency larger than the Brunt-V\\"ais\\"al\\"a frequency are detected and experimental results agree very well with theoretical predictions. The amplitude of the different harmonics after reflection are also obtained.

Gostiaux, L; Didelle, H; Sommeria, J; Viboud, S; Gostiaux, Louis; Dauxois, Thierry; Didelle, Henri; Sommeria, Joel; Viboud, Samuel

2006-01-01

265

Breaking of Waves over a Steep Bottom Slope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The thesis deals with the wave breaking process of waves propagating over a steep submerged bottom slope. The amount of energy dissipated in the wave breaking process is focused upon. An extensive number of experimental tests (>400) using regular and irregular waves breaking over a simulated reef in the hydraulic laboratory are performed. Based on the experimental tests several formulae developed. Formulae are capable of predicting the transmitted wave height and wave energy flux, respectivel...

Jensen, Morten S.

2004-01-01

266

Olive production systems on sloping land: Prospects and scenarios  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The ultimate objective of the EU Olivero project was to improve the quality of life of the rural population and to assure the sustainable use of the natural resources of land and water in the sloping and mountainous olive production systems (SMOPS) areas in Southern Europe. One specific objective was to develop, with end-users, alternative future scenarios for olive orchards in the five Olivero target areas. This paper discusses the development of these scenarios, and their socio-economic and...

Graaff, J.; Duran Zuazo, V. H.; Jones, N.; Fleskens, L.

2008-01-01

267

Time shift of pulses due to dispersion slope and nonlinearity  

Energy Technology Data Exchange (ETDEWEB)

The authors show that the time delay of optical pulses traveling in long fibers is influenced by the dispersion slope and the fiber nonlinearity. Consequently, one or more new pulses that are inserted by add-drop operations into a pulse train that has already traveled a long distance may shift relative to the old pulses. This time shift delays the initial pulses more than the newly inserted ones, so that the newly inserted pulses can leave their time frames, leading to errors.

Marcuse, D.; Menyuk, C.R.; Holzloehner, R.

1999-12-01

268

Unitarity lower bounds on logarithmic slope of diffraction peak  

International Nuclear Information System (INIS)

Via Lagrange multipliers for equality and inequality constraints, rigorous lower bounds on the logarithmic slope of diffraction peak are derived assuming unitarity and a fixed total elastic ?sub(el) and forward differential d?sub(el)/d? (0deg) cross section. Comparison with the experimental data of antip p and pp scattering shows that the relative departure from the unitarity bound is about 11% for all Psub(LAB) > 1 GeV/c. (author)

1981-01-01

269

Stability of vegetated slopes in unsaturated conditions: a numerical study  

Science.gov (United States)

Extreme rainfall events can trigger shallow landslides with failure planes located in soils far from saturated conditions. The stability of shallow soils on very steep slopes under unsaturated conditions can be highly influenced by the vegetation, according to both geo-mechanical and soil-hydrological factors, particularly in regions characterized by a strong climatic seasonality. The root structure of the vegetation reinforces the shallow soils, by providing additional apparent cohesion to the soil. The root water uptake enhances the stability by increasing the frequency of high suction pressure heads in the soil layers explored by the roots. In water controlled eco-systems, such as Mediterranean areas, these two factors are mutually related. Plants develop their root structure in order to optimize the uptake of the water available in the soil, since water availability is limited during the growing season. In this study we present the results of some numerical experiments with the aim to assess the relative importance of these two factors. We simulated the soil water dynamics within homogeneous loamy-sand soils, assuming climatic conditions and root structures typically observed in a deciduous forest of central and southern Italy. An infinite slope stability model is employed for assessing the temporal evolution of the contribute of the soil suction regime to the slope stability, as compared with the contribute of the soil root reinforcement. The results suggest that, during the wet season, the effect of the soil suction state on slope stability is much smaller than that attributable to the mechanical reinforcement provided by the root structure, at least within soil depths explored by the plant roots. Instead, during the growing and dry summer seasons, the soil suction state is far more relevant than the mechanical reinforcement. Thus, accounting for the antecedent soil suction state can be relevant for an appropriate prediction of shallow landslide hazards in those Mediterranean regions, where shallow landslides are triggered by intense convective rainstorms of short duration, occurring more frequently during the growing and dry seasons.

Battista Chirico, Giovanni; Borga, Marco; Tarolli, Paolo; Rigon, Riccardo; Preti, Federico

2014-05-01

270

Estimation of streamflow by slope regional dependency function  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Kriging is one of the most developed methodologies in the regional variable modeling. However, one of its drawbacks is that the influence radius can not be determined by this method. In which distance and in what ratio that pivot station is influenced from adjacent sites is rather often encountered problem in practical applications. Regional weighting functions obtained from available data consist of several broken lines. Each line has different slopes which represent the similarity and the c...

Altunkaynak, A.

2008-01-01

271

Strength, slope and variability of marine latitudinal gradients  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Latitudinal declines of species richness from the tropics to the poles represent a general spatial pattern of diversity on land. For the marine realm, the generality of this pattern has frequently been questioned. Here, I use a database with nearly 600 published gradients (198 of which were marine) to assess whether there is a marine latitudinal diversity gradient of similar average strength and slope as that for terrestrial organisms. Using meta-analysis techniques, I also tested which chara...

2004-01-01

272

Slope heuristics for variable selection and clustering via Gaussian mixtures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Specific Gaussian mixtures are considered to solve simultaneously variable selection and clustering problems. A penalized likelihood criterion is proposed in Maugis and Michel (2008) to choose the number of mixture components and the relevant variable subset. This criterion is depending on unknown constants to be approximated in practical situations. A "slope heuristics" method is proposed and experimented to deal with this practical problem in this context. Numerical experiments on simulated...

Maugis, Cathy; Michel, Bertrand

2008-01-01

273

Slope Stability Analysis of Itakpe Iron Ore Mine, Itakpe, Nigeria  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The slope stability of the Itakpe Iron Ore Mine has been carried out using computer software, ROCKPACK III. One hundred and twenty three dip and dip direction values were obtained using compass clinometer. The Itakpe Iron Ore Mine was divided into four benches; 241 - 258 m, 263 - 275 m, 276 - 286 m and 308 - 312 m. Joints along the discontinuities were mapped. The data obtained were analyzed using ROCKPACK III. The results indicate that the discontinuities within the critical zone are potenti...

Adebimpe, Rasheed A.; Jide Muili Akande; Chinwuba Arum

2011-01-01

274

Stability of infinite slopes under transient partially saturated seepage conditions  

Science.gov (United States)

Prediction of the location and timing of rainfall-induced shallow landslides is desired by organizations responsible for hazard management and warnings. However, hydrologic and mechanical processes in the vadose zone complicate such predictions. Infiltrating rainfall must typically pass through an unsaturated layer before reaching the irregular and usually discontinuous shallow water table. This process is dynamic and a function of precipitation intensity and duration, the initial moisture conditions and hydrologic properties of the hillside materials, and the geometry, stratigraphy, and vegetation of the hillslope. As a result, pore water pressures, volumetric water content, effective stress, and thus the propensity for landsliding vary over seasonal and shorter time scales. We apply a general framework for assessing the stability of infinite slopes under transient variably saturated conditions. The framework includes profiles of pressure head and volumetric water content combined with a general effective stress for slope stability analysis. The general effective stress, or suction stress, provides a means for rigorous quantification of stress changes due to rainfall and infiltration and thus the analysis of slope stability over the range of volumetric water contents and pressure heads relevant to shallow landslide initiation. We present results using an analytical solution for transient infiltration for a range of soil texture and hydrological properties typical of landslide-prone hillslopes and show the effect of these properties on the timing and depth of slope failure. We follow by analyzing field-monitoring data acquired prior to shallow landslide failure of a hillside near Seattle, Washington, and show that the timing of the slide was predictable using measured pressure head and volumetric water content and show how the approach can be used in a forward manner using a numerical model for transient infiltration.

Godt, Jonathan W.; ?Ener-Kaya, Ba?Ak; Lu, Ning; Baum, Rex L.

2012-05-01

275

Electric vehicle's electricity consumption on a road with different slope  

Science.gov (United States)

In this paper, we propose an extended car-following model and an electricity consumption model to study the effects of the road's slope on the electric vehicle's electricity consumption. The numerical results show that each electric vehicle's electricity consumption increases with the uphill's tilt angle and decreases with the downhill's tilt angle. In addition, each electric vehicle's electricity consumption increases with the uphill's (downhill's) length under a certain tilt angle.

Yang, S. C.; Li, M.; Lin, Y.; Tang, T. Q.

2014-05-01

276

Patterns of precursory rockfall prior to slope failure.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper we examine data generated using high-resolution three-dimensional laser scanning monitoring of coastal rock cliffs. These data are used to identify spatial and temporal patterns in rockfall activity behavior prior to slope failure. Analysis of the data suggests that given sufficient measurement precision precursory behavior, here manifest as the rate of rockfall activity prior to failure, can be detected, measured, and monitored. Environmental conditions appear to have a diminis...

2007-01-01

277

North Slope Decision Support for Water Resource Planning and Management  

Energy Technology Data Exchange (ETDEWEB)

The objective of this project was to enhance the water resource decision-making process with respect to oil and gas exploration/production activities on Alaska’s North Slope. To this end, a web-based software tool was developed to allow stakeholders to assemble, evaluate, and communicate relevant information between and amongst themselves. The software, termed North Slope Decision Support System (NSDSS), is a visually-referenced database that provides a platform for running complex natural system, planning, and optimization models. The NSDSS design was based upon community input garnered during a series of stakeholder workshops, and the end product software is freely available to all stakeholders via the project website. The tool now resides on servers hosted by the UAF Water and Environmental Research Center, and will remain accessible and free-of-charge for all interested stakeholders. The development of the tool fostered new advances in the area of data evaluation and decision support technologies, and the finished product is envisioned to enhance water resource planning activities on Alaska’s North Slope.

Schnabel, William; Brumbelow, Kelly

2013-03-31

278

Applications and developments of the interferometric strain/slope rosette  

Science.gov (United States)

Chapter 1 introduces the technical background and concepts assumed in the subsequent chapters of the dissertation. A basic description of ISSR operation and set-up is given. Application of the ISSR to residual stress measurements using incremental-hole drilling is described. Concepts and motivation of Nano-ISSR and Multi-ISSR are introduced. Background is given on digital spatial filtering to separate out individual gauge interference patterns. Chapter 2 details the ISSR method for residual stress measurements, covering: (a) derivation of ISSR residual stress measurement inverse model utilizing both strain and slope, (b) finite element model utilized for calculation of ISSR hole-drilling coefficients, (c) experimental study of ISSR measurement of pure strains/slopes on a thin-plate with hole, (d) experimental measurements of incremental ISSR strains/slopes on a shot-peened Titanium-alloy block, and (e) theory and numerical implementation of Tikhonov regularized residual stress solutions on the Titanium-alloy block. Chapter 3 describes a feasibility study on Nano-ISSR that utilized numerical integration of the Rayleigh-Sommerfeld optical scattering equation to predict the sensitivity and feasibility of ISSR measurements with gauge-lengths at the nanometer scale (-1000 nm). The measurement resolution of the Nano-ISSR was estimated to be 0.00 1% for normal strain and 0.1 nm for in-plane relative displacement based on UV laser illumination with 200 nm wavelength and currently available digital cameras.

Tjhung, Tana

279

Monitoring slope deformation with quadrilaterals for pipeline risk management  

Energy Technology Data Exchange (ETDEWEB)

A quadrilateral is a geometric form defined by 4 points in an approximately square plan configuration. Quadrilateral measurements can be used to calculate ground-surface deformation and strain, and can serve as an economical alternative to the placement of strain gauges on pipelines in areas of active or potential slope movements. This paper provided details of a study in which 3 contiguous quadrilaterals were installed in a landslide-prone area of southern California to aid in the monitoring of a slope between the main scarp of a recently active landslide and a pipeline bridge foundation. Repeated measurements of the distances between the points and relative elevations of the quadrilaterals allowed for the calculation of displacements across landslide cracks and strains and tilts on landslide surfaces. Results of the study showed that inferences about pipeline strain may be made based on quadrilateral-based ground surface strain. Quadrilaterals place directly over or in close proximity to the buried pipeline provided the most valuable data. It was observed that while earth movements were transferred to the buried pipeline, soil-pipeline interaction effects resulted in more deformation of the soil than in the pipeline. The study also suggested that quadrilaterals can also be used to provide quantitative slope deformation data for pipeline risk management processes. It was concluded that quadrilaterals are well-suited for the monitoring of ground settlement, lateral, or rotational ground movement, as well as subsidence, uplift, and creep. 5 refs., 5 tabs., 7 figs.

Keaton, J.R. [AMEC Earth and Environmental, Anaheim, CA (United States); Gailing, R.W. [Southern California Gas Co., Los Angeles, CA (United States)

2004-07-01

280

Native plants for erosion control in urban river slopes  

Directory of Open Access Journals (Sweden)

Full Text Available Mechanical and structural erosion of soils is produced by the loss of the vegetal cover and the action of rain on unprotected surfaces. Raindrop impact, transport and sediment deposition leads to landslides and slope instability and soil loss. In Costa Rica, water bodies have been negatively impacted by urban development and both water resources and soils have become more vulnerable. This is the case of the Pirro river micro watershed where riverbed vegetation has been replaced by constructions producing erosion problems in its slopes. In order to evaluate how native plants favor sediment control and prevent this sediment from been deposited in the river, eight experimental plots were installed. Four treatments were established: A (Costus pulverulentus Presl, B (Heliconia tortuosa (Griggs Standl., C (Vetiveria zizanioides (L. Nash and D (control. Sediments were collected weekly during the rainy and transitional seasons. A clear relation between rainfall intensity and sediment production was determined, particularly for intensities higher than 50 mm h-1. Significant differences were also determined between the treatments and the efficiency order was B >A > C >D, with the native plants being the most efficient in terms of sediment control. The use of native plants is recommended for the management and rehabilitation of slopes near urban rivers due to their ecological value and their capability for sediment control.

Virginia Alvarado

2014-03-01

 
 
 
 
281

Road surface drainage, channel initiation, and slope instability  

Science.gov (United States)

Field surveys of road drainage concentration at three sites in the western United States are used to test simple models relating channel initiation and shallow landsliding to ground slope and contributing area thresholds. The form of boundaries between data for locations where road drainage concentration is associated with either shallow landsliding, channel initiation by overland flow, or no observable geomorphic effect is consistent with theoretically derived drainage area-slope relations. Comparison of survey data with results of previous studies in these areas indicates that the drainage area required to support a channel head is smaller for road-related runoff than for undisturbed slopes. Contrary to current land management paradigms in the Pacific Northwest, drainage concentration from ridgetop roads may cause both landsliding and integration of the channel and road networks. Road drainage concentration increases the effective length of the channel network and strongly influences the distribution of erosional processes in each of the study areas. The approach of using field reconnaissance to establish thresholds for erosion associated with road drainage provides a useful method to define regional criteria for road design that should reduce impacts on downstream channel systems.

Montgomery, David R.

1994-06-01

282

CONCERNING THE SLOPE OF THE CEPHEID PERIOD-LUMINOSITY RELATION  

International Nuclear Information System (INIS)

We discuss the impact of possible differences in the slope of the Cepheid period-luminosity (PL) relation on the determination of extragalactic distances in the context of recent studies that suggest changes in this slope. We show that the Wesenheit function W = V - R x (V - I), widely used for the determination of the Cepheid distances, is expected to be highly insensitive to changes in the slope of the underlying (monochromatic) PL relations. This occurs because the reddening trajectories in the color-magnitude plane are closely parallel to lines of constant period. As a result W-based PL relations have extremely low-residual dispersion, which is because differential (and the total line of sight) reddening is eliminated in the definition of W and the residual scatter due to a star's intrinsic color/position within the Cepheid is also largely insensitive to W. Basic equations are presented and graphically illustrated, showing the insensitivity of W to changes in the monochromatic PL relations.

2009-05-10

283

An Adaptive Slope Compensation Circuit and its Application  

Directory of Open Access Journals (Sweden)

Full Text Available To resolve over-compensation problem in the current mode PWM switch power, a new adaptive slope compensation circuit is proposed in this study. In the circuit, the difference between the output and input voltage is positive correlative with the duty cycle of switch signal which is used to generate the control signal varying with the duty ratio. The control signal is used to control the gate voltage of MOS operating in linear region which changes the linear drain-source resistance. With clamping circuit, a proportional ramp voltage with controllable slope is produced and amplified for compensation system by two stage amplifier. This compensation voltage is almost ideal which can reduce the negative effect of over-compensation farthest. This circuit is applied to an LED driver IC and simulated in Cadence with CSMC 0.5um BiCMOS library. The results show that the boost driver circuit using adaptive compensation has about 28% dynamic response time reducing compared with the settled slope compensation. Therefore the proposed compensation circuit can improve systems dynamic responsibility effectively.

Chen Guanghua

2013-01-01

284

Slope stability probability classification, Waikato Coal Measures, New Zealand  

Energy Technology Data Exchange (ETDEWEB)

Ferm classified lithological units have been identified and described in the Waikato Coal Measures in open pits in the Waikato coal region. These lithological units have been classified geotechnically with mechanical tests and discontinuity measurements. Using these measurements, slope stability probability classification (SSPC) have been quantified based on an adaption of Hack's SSPC system which places less influence on rock quality designation and unconfined compressive strength than previous rock mass rating systems. An attempt has been made to modify the Hack weathering susceptibility rating by using chemical index of alteration values from XRF major element analysis. Another major component of this adapted SSPC system is the inclusion of rock moisture content effects on slope stability. The paper explains the systematic initial approach of using the adapted SSPC system to classify slope stability in the Waikato open pit coal mines. The XRF major element results obtained for lithologies in the Waikato coal region may be a useful mine management tool to quantify stratigraphic thickness and palaeoweathering from wash drill cuttings. 14 refs., 7 figs., 3 tabs.

Lindsay, P.; Campbell, R.; Fergusson, D.A.; Ferm, J.C.; Gillard, G.R.; Moore, T.A. [CRL Energy Ltd., Christchurch (New Zealand)

1999-07-01

285

Comparison of slope stability in two Brazilian municipal landfills  

International Nuclear Information System (INIS)

The implementation of landfill gas to energy (LFGTE) projects has greatly assisted in reducing the greenhouse gases and air pollutants, leading to an improved local air quality and reduced health risks. The majority of cities in developing countries still dispose of their municipal waste in uncontrolled 'open dumps.' Municipal solid waste landfill construction practices and operating procedures in these countries pose a challenge to implementation of LFGTE projects because of concern about damage to the gas collection infrastructure (horizontal headers and vertical wells) caused by minor, relatively shallow slumps and slides within the waste mass. While major slope failures can and have occurred, such failures in most cases have been shown to involve contributory factors or triggers such as high pore pressures, weak foundation soil or failure along weak geosynthetic interfaces. Many researchers who have studied waste mechanics propose that the shear strength of municipal waste is sufficient such that major deep-seated catastrophic failures under most circumstances require such contributory factors. Obviously, evaluation of such potential major failures requires expert analysis by geotechnical specialists with detailed site-specific information regarding foundation soils, interface shearing resistances and pore pressures both within the waste and in clayey barrier layers or foundation soils. The objective of this paper is to evaluate the potential use of very simple stability analyses which can be used to study the potential for slumps and slides within the waste mass and which may represent a significant constraint on construction and development of the landfill, on reclamation and closure and on the feasibility of a LFGTE project. The stability analyses rely on site-specific but simple estimates of the unit weight of waste and the pore pressure conditions and use 'generic' published shear strength envelopes for municipal waste. Application of the slope stability analysis method is presented in a case study of two Brazilian landfill sites; the Cruz das Almas Landfill in Maceio and the Muribeca Landfill in Recife. The Muribeca site has never recorded a slope failure and is much larger and better-maintained when compared to the Maceio site at which numerous minor slumps and slides have been observed. Conventional limit-equilibrium analysis was used to calculate factors of safety for stability of the landfill side slopes. Results indicate that the Muribeca site is more stable with computed factors of safety values in the range 1.6-2.4 compared with computed values ranging from 0.9 to 1.4 for the Maceio site at which slope failures have been known to occur. The results suggest that this approach may be useful as a screening-level tool when considering the feasibility of implementing LFGTE projects

2008-01-01

286

Comparison of slope stability in two Brazilian municipal landfills.  

Science.gov (United States)

The implementation of landfill gas to energy (LFGTE) projects has greatly assisted in reducing the greenhouse gases and air pollutants, leading to an improved local air quality and reduced health risks. The majority of cities in developing countries still dispose of their municipal waste in uncontrolled 'open dumps.' Municipal solid waste landfill construction practices and operating procedures in these countries pose a challenge to implementation of LFGTE projects because of concern about damage to the gas collection infrastructure (horizontal headers and vertical wells) caused by minor, relatively shallow slumps and slides within the waste mass. While major slope failures can and have occurred, such failures in most cases have been shown to involve contributory factors or triggers such as high pore pressures, weak foundation soil or failure along weak geosynthetic interfaces. Many researchers who have studied waste mechanics propose that the shear strength of municipal waste is sufficient such that major deep-seated catastrophic failures under most circumstances require such contributory factors. Obviously, evaluation of such potential major failures requires expert analysis by geotechnical specialists with detailed site-specific information regarding foundation soils, interface shearing resistances and pore pressures both within the waste and in clayey barrier layers or foundation soils. The objective of this paper is to evaluate the potential use of very simple stability analyses which can be used to study the potential for slumps and slides within the waste mass and which may represent a significant constraint on construction and development of the landfill, on reclamation and closure and on the feasibility of a LFGTE project. The stability analyses rely on site-specific but simple estimates of the unit weight of waste and the pore pressure conditions and use "generic" published shear strength envelopes for municipal waste. Application of the slope stability analysis method is presented in a case study of two Brazilian landfill sites; the Cruz das Almas Landfill in Maceio and the Muribeca Landfill in Recife. The Muribeca site has never recorded a slope failure and is much larger and better-maintained when compared to the Maceio site at which numerous minor slumps and slides have been observed. Conventional limit-equilibrium analysis was used to calculate factors of safety for stability of the landfill side slopes. Results indicate that the Muribeca site is more stable with computed factors of safety values in the range 1.6-2.4 compared with computed values ranging from 0.9 to 1.4 for the Maceio site at which slope failures have been known to occur. The results suggest that this approach may be useful as a screening-level tool when considering the feasibility of implementing LFGTE projects. PMID:17897819

Gharabaghi, B; Singh, M K; Inkratas, C; Fleming, I R; McBean, E

2008-01-01

287

GIS modelling of slope stability in Phewa Tal watershed, Nepal  

Science.gov (United States)

Hazards are an inherent but dangerous and costly element of mountainous environments. Conventional maps of mountain hazards provide useful inventories of hazardous sites but provide little insight into the operation of the hazards. Furthermore, this approach tends to rely heavily on subjective interpretation of the landscape, which means that the results can not be replicated or transferred to other areas. Thus, alternative approaches employing the quantitative capabilities of geographic information systems (GIS) to model and predict slope stability are receiving increasing attention. This paper reports on the use of a diverse GIS database, compiled primarily from existing maps and aerial photographs, to construct a regional model of slope stability in Phewa Tal watershed, Nepal. An integral part of the research was to explore an alternative approach to the commonly used grid cell approach by employing geomorphometrically significant terrain units. The terrain units employed were created by generating line networks representing local maxima and minima extracted from elevation and curvature surfaces. One of the chief benefits of applying GIS technology in this research was the ability to georeference all of the attribute data to these terrain units. In doing so, it allowed the database to be exported into an external statistical package, where the terrain units could be statistically explored as the basic analytical unit. The application of a variety of statistical techniques resulted in logistic regression being selected as the most useful. Logistic regression successfully predicted terrain units as being either stable or unstable at a rate of approximately 90% concordance with a conventionally produced map of slope stability. The statistical probabilities of terrain unit stability were imported back into the GIS to produce a map of predicted slope stability that compared well with the conventional map of slope stability. The findings of this research suggest that the use of geomorphometrically significant terrain units extracted from a digital elevation model (DEM) are an efficient alternative to approaches using regular grid cells. In particular, the terrain units facilitated the use of logistic regression, and significantly decreased the amount of computing costs. Finally, this research also suggests that important information can be gathered from existing information sources, such as maps, aerial photographs, and written documents, thereby limiting the need for costly and time consuming field work at the reconnaissance level. Based on this latter finding, other information sources, such as satellite imagery, should be examined.

Rowbotham, David N.; Dudycha, Douglas

1998-12-01

288

Quasi-stable Slope-Failure Dams in High Asia  

Science.gov (United States)

Collapses of steep mountain slopes in the Himalaya, Karakoram, Pamir, Hindu Kush, and Tibetan Plateau are well known as a result of:(1) generally high seismicity in active tectonic areas; (2) prior deglaciation leaving undercut, unstable cliffs; (3) present-day debuttressing of rock cliffs by glacial down-wasting in conditions of global warming; and (4) degradation of permafrost cohesion and water-ice cementation in high mountain slopes. Landslide dams across mountain rivers are also well known worldwide and generally do not endure for long because of the common landslide-lake outburst floods (LLOF) whose discharge is commonly sufficiently large to remove much of the dam in a short time. A number of massive slope-failure dams in south High Asia, however, have endured for centuries and require explanations for the length of duration, whereas recent examples require robust assessment for better predictive hazard analysis. Three main factors contribute to longevity of slope-failure dams: (1) mega-rocks >15-30 m that inhibit dam failure in overflow breaches; (2) mega-porosity wherein incoming discharge to the landslide lake is balanced by subterranean water through-flow within the landslide dam; (3) impermeable clay fills caused by remobilization of prior lacustrine-dammed sediment that impart dam strength to allow lasting integrity for a time, and (4) climate-change induced lake-level lowering. Several examples of long-lived or unusually stable, slope-failure dams associated with pronounced structural/tectonic associations include: (1) Pangong Tso, Ladakh and Tibet; (2) Lake Shewa, Afghanistan; (3) Sarez Lake, Tajikistan; and (4) Lake Hunza, Pakistan. Pangong Tso and Lake Shewa were emplaced thousands of years ago and only Lake Shewa shows some instability of the dam front where percolating water maintains lake level but may be causing new slumping. Sarez Lake behind the Usoi landslide dam was emplaced by an earthquake in 1911 and maintains its level by seepage. Lake Hunza developed behind a new landslide dam in 2010 but remobilized lacustrine clay from a prior damming event and large blocks have maintained dam integrity in spite of overflow beginning 29 May 2010. Character and condition of landslide dams clearly controls whether LLOF or stability will prevail.

Shroder, J. F.

2010-12-01

289

Assessment of Rockfall Hazard along the Road Cut Slopes of State Highway-72, Maharashtra, India  

Directory of Open Access Journals (Sweden)

Full Text Available Rockfall is a major problem in high hill slopes and rocky mountainous regions and construction of highways at these rockfall prone areas often require stable slopes. The causes of rockfall are presence of discontinuities, high angle cut slopes, heavy rainfall, and unplanned slope geometry etc. Slope geometry is one of the most triggering parameters for rockfall, when there are variations in slope angle along the profile of slope. The Present study involves rockfall hazard assessment of road cut slopes for 15 km distance starting from Mahabaleshwar town along State Highway-72 (SH-72. The vertical to subvertical cut slopes are prone to instability due to unfavorable orientation of discontinuities in slope face of weathered and altered basaltic rockmass. The predominant type of instability has been found as wedge type failure involving medium to large size blocks. In order to investigate the existing stability conditions, analyses were carried out at two locations under different slope conditions. The kinematic analysis was performed using stereographic projection method. RockFall 4.0 numerical simulator software was used to calculate the maximum bounce heights, total kinetic energies and translational velocities of the falling rockmass blocks, and a comparative analysis is presented with increasing the mass of blocks and height of the slope. The result of numerical analysis shows that varying slope angle geometry creates more problems as compared to the mass of blocks in the scenario of rockfall.

M. Ahmad

2013-01-01

290

Soil roughness, slope and surface storage relationship for impervious areas  

Science.gov (United States)

SummaryThe study of the relationships between surface roughness, local slope gradient and maximum volume of water storage in surface depressions is a fundamental element in the development of hydrological models to be used in soil and water conservation strategies. Good estimates of the maximum volume of water storage are important for runoff assessment during rainfall events. Some attempts to link surface storage to parameters such as indices of surface roughness and, more rarely, local gradient have been proposed by several authors with empirical equations often conflicting between them and usually based on a narrow range of slope gradients. This suggests care in selecting any of the proposed equations or models and invites one to verify the existence of more realistic experimental relationships, based on physical models of the surfaces and valid for a larger range of gradients. The aim of this study is to develop such a relation for predicting/estimating the maximum volume of water that a soil surface, with given roughness characteristics and local slope gradient, can store. Experimental work has been carried out in order to reproduce reliable rough surfaces able to maintain the following properties during the experimental activity: (a) impervious surface to avoid biased storage determination; (b) stable, un-erodible surfaces to avoid changes of retention volume during tests; (c) absence of hydrophobic behaviour. To meet the conditions a-c we generate physical surfaces with various roughness magnitude using plasticine (emulsion of non-expansible clay and oil). The plasticine surface, reproducing surfaces of arable soils, was then wetted and dirtied with a very fine timber sawdust. This reduced the natural hydrophobic behaviour of the plasticine to an undetectable value. Storage experiments were conducted with plasticine rough surfaces on top of large rigid polystyrene plates inclined at different slope gradient: 2%, 5%, 10%, 20%, 30%. Roughness data collected on the generated plasticine surfaces were successfully compared with roughness data collected on real soil surfaces for similar conditions. A set of roughness indices was computed for each surface using roughness profiles measured with a laser profile meter. Roughness indices included quantiles of the Abbot-Firestone curve, which is used in surface metrology for industrial application to characterize surface roughness in a non-parametric approach ( Whitehouse, 1994). Storage data were fitted with an empirical equation (double negative exponential of roughness and slope). Several roughness indices resulted well related to storage. The better results were obtained using the Abbot-Firestone curve parameter P100. Beside this storage empirical model (SEM) a geometrical model was also developed, trying to give a more physical basis to the result obtained so far. Depression geometry was approximated with spherical cups. A general physical model was derived (storage cup model - SCM). The cup approximation identifies where roughness elevation comes in and how it relates to slope gradient in defining depression volume. Moreover, the exponential decay used for assessing slope effect on storage volume in the empirical model of Eqs. (8) and (9) emerges as consistent with distribution of cup sizes.

Borselli, Lorenzo; Torri, Dino

2010-11-01

291

ANALYSIS OF EXISTING METHODS OF STUDY OF STRAIN-STRESS STATE OF ROCKS ON SLIP SLOPE  

Directory of Open Access Journals (Sweden)

Full Text Available The methods for analysis of strain-stress state of rocks on slip slope as well as the methods of study of engineering and geological properties of rocks that compose the slip slope are considered.

Ye. Ugnenko

2010-01-01

292

Protection Roles of Tea-Citrus Garden on Slopes (N Iran)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study investigates the effects of vegetation on the stability of slopes using the finite element method. Parametric studies were performed to assess the sensitivity of the stability of a slope to the variation in the key vegetation and soil parameters. Results show that vegetation plays an important role in stabilizing shallow-seated failure of slopes and significantly affects stability. As Iran has a long history of landslides, this research deals with the effect of scrubs on slope stab...

2007-01-01

293

Laboratory Experiments on Steady State Seepage-Induced Landslides Using Slope Models and Sensors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A thorough understanding of the failure initiation process is crucial in the development of physicallybased early warning system for landslides and slope failures. Laboratory-scale slope models were constructed and subjected to instability through simulated groundwater infiltration. This is done by progressively increasing the water level in the upslope tank and allowing water to infiltrate laterally towards the toe of the slope. Physical changes in the slope models were recorded by tilt sens...

2011-01-01

294

Applications of Cs-137 and soil trapping methods for studying slope processes in the Carpathian foothills  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Areas of soil degradation and sedimentation have been delimited within a single, representative for the Carpathian Foothills, slope profile. Two methods: Cs-137 and soil trapping have been used. Soil degradation on the slope used as a pastureland is generally small, with the most intensive degradation in the mid slope. Once the slope was cultivated the process of erosion and soil wash must have been more intensive which is evidenced by high Cs-137 content within the valley bottom deposits. Hi...

Chelmicki, Wojciech; Swiechowicz, Jolanta

1992-01-01

295

?????? ???????????? ???????????? ??? ??????? ????????? ?? ???????? ?????????? ??????? ???????? ??????? ?nalysis of the effectiveness of countermeasures to protect the ecosystems on slopes landscapes using box models ?????? ????????????? ???????? ??? ?????? ????????? ?? ????????? ?????????? ??????? ???????? ???????  

Directory of Open Access Journals (Sweden)

Full Text Available  ??? ??????? ???????????? ???????????? ??? ??????? ????????? ??? ?????????????? ??????????? ???????? ????-????? ???????? ??????????. ????????? ??????????? ???????? ???????? ????????????? ? ???????? ??????????? ??????? ???????? ??????? ?? ????????????? ????????????. ?????????? ??????????? ?????????? ??????? ?? ?????? ??????????? ????????  ??????  ????????????. For the analysis of efficiency of counter-measures on defence of ecosystems  from radioactive contamination is created block-scheme  of  slope`s ecosystem. The design of processes of migration of radionuclides in slope`s  ecosystems  is conducted by the method  of box models  with the use of counter-measures.  The results of design allow to estimate and choose the optimum algorithm  of choice of counter-measures.   ??? ??????? ????????????? ???????? ??? ?????? ????????? ?? ?????????????? ??????????? ?????????? ?? ????-????? ????????? ??????????. ????????? ????????????? ????????? ???????? ????????????? ? ????????? ??????????? ??????? ???????? ??????? ? ?????????????? ????????. ?????????? ?????????????? ????????? ??????? ? ??????? ??????????? ???????? ?????? ????????.

?.?. ???????????

2006-04-01

296

Evaluation of Slope Assessment System in Predicting Landslides along Roads Underlain by Granitic Formation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A slope assessment is to estimate the probability of occurrence and likely severity of landslides in a given area. This study evaluates two existing Slope Assessment Systems (SAS) for predicting landslide at the micro level of assessment developed by the Public Works Department of Malaysia, namely the Slope Information Management System (SIMS) and the Slope Management and Risk Tracking System (SMART). From the results of this study, it appears that none of the existing SAS is satisfactory for...

Huat, Bujang B. K.; Jamaludin, S.

2005-01-01

297

Methodology to evaluate rock slope stability under seismic conditions at Solà de Santa Coloma, Andorra  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An analytical methodology is presented to evaluate rock slope stability under seismic conditions by considering the geomechanical and topographic properties of a slope. The objective is to locate potential rockfall source areas and evaluate their susceptibility in terms of probability of failure. For this purpose, the slope face of a study area is discretized into cells having homogenous aspect, slope angle, rock properties and joint set orientations. A pseudostatic limit equilibrium analysis...

2009-01-01

298

The evolution of slope failures: mechanisms of rupture propagation  

Science.gov (United States)

Forecasting the occurrence of large, catastrophic slope failures remains very problematic. It is clear that in order advance this field a greater understanding is needed of the processes through which failure occurs. In particular, there is a need to comprehend the processes through which a rupture develops and propagates through the slope, and the nature of the inter-relationship between the stress and strain states of the landslide mass. To this end, a detailed analysis has been undertaken of the movement records for the Selborme Cutting slope failure, in which failure was deliberately triggered through pore pressure elevation. The data demonstrate that it is possible to determine the processes occurring in the basal region of the landslide, and thus controlling the movement of the mass, from the surface movement patterns. In particular, it is clear that the process of rupture development and propagation has a unique signature, allowing the development of the rupture to be traced from detailed surface monitoring. For landslides undergoing first time failure through rupture propagation, this allows the prediction of the time of failure as per the "Saito" approach. It is shown that for such predictions to be reliable, data from a number of points across the landslide mass are needed. Interestingly, due to the complex stress regime in that region, data from the crown may not be appropriate for failure prediction. Based upon these results, the application of new techniques for the detailed assessment of spatial patterns of the development of strain may potentially allow a new insight into the development of rupture surfaces and may ultimately permit forecasting of the temporal occurrence of failure.

Petley, D. N.

2004-03-01

299

The evolution of slope failures: mechanisms of rupture propagation  

Directory of Open Access Journals (Sweden)

Full Text Available Forecasting the occurrence of large, catastrophic slope failures remains very problematic. It is clear that in order advance this field a greater understanding is needed of the processes through which failure occurs. In particular, there is a need to comprehend the processes through which a rupture develops and propagates through the slope, and the nature of the inter-relationship between the stress and strain states of the landslide mass. To this end, a detailed analysis has been undertaken of the movement records for the Selborme Cutting slope failure, in which failure was deliberately triggered through pore pressure elevation. The data demonstrate that it is possible to determine the processes occurring in the basal region of the landslide, and thus controlling the movement of the mass, from the surface movement patterns. In particular, it is clear that the process of rupture development and propagation has a unique signature, allowing the development of the rupture to be traced from detailed surface monitoring. For landslides undergoing first time failure through rupture propagation, this allows the prediction of the time of failure as per the 'Saito' approach. It is shown that for such predictions to be reliable, data from a number of points across the landslide mass are needed. Interestingly, due to the complex stress regime in that region, data from the crown may not be appropriate for failure prediction. Based upon these results, the application of new techniques for the detailed assessment of spatial patterns of the development of strain may potentially allow a new insight into the development of rupture surfaces and may ultimately permit forecasting of the temporal occurrence of failure.

D. N. Petley

2004-01-01

300

Slopes To Prevent Trapping of Bubbles in Microfluidic Channels  

Science.gov (United States)

The idea of designing a microfluidic channel to slope upward along the direction of flow of the liquid in the channel has been conceived to help prevent trapping of gas bubbles in the channel. In the original application that gave rise to this idea, the microfluidic channels are parts of micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. It is necessary to prevent trapping of gas bubbles in these devices because uninterrupted liquid pathways are essential for sustaining the electrical conduction and flows that are essential for CE. The idea is also applicable to microfluidic devices that may be developed for similar terrestrial microCE biotechnological applications or other terrestrial applications in which trapping of bubbles in microfluidic channels cannot be tolerated. A typical microCE device in the original application includes, among other things, multiple layers of borosilicate float glass wafers. Microfluidic channels are formed in the wafers, typically by use of wet chemical etching. The figure presents a simplified cross section of part of such a device in which the CE channel is formed in the lowermost wafer (denoted the channel wafer) and, according to the present innovation, slopes upward into a via hole in another wafer (denoted the manifold wafer) lying immediately above the channel wafer. Another feature of the present innovation is that the via hole in the manifold wafer is made to taper to a wider opening at the top to further reduce the tendency to trap bubbles. At the time of reporting the information for this article, an effort to identify an optimum technique for forming the slope and the taper was in progress. Of the techniques considered thus far, the one considered to be most promising is precision milling by use of femtosecond laser pulses. Other similar techniques that may work equally well are precision milling using a focused ion beam, or a small diamond-tipped drill bit.

Greer, Harold E.; Lee, Michael C.; Smith, J. Anthony; Willis, Peter A.

2010-01-01

 
 
 
 
301

Adaptive glide slope control for parafoil and payload aircraft  

Science.gov (United States)

Airdrop systems provide a unique capability of delivering large payloads to undeveloped and inaccessible locations. Traditionally, these systems have been unguided, requiring large landing zones and drops from low altitude. The invention of the steerable, gliding, ram-air parafoil enabled the possibility of precision aerial payload delivery. In practice, the gliding ability of the ram-air parafoil can actually create major problems for airdrop systems by making them more susceptible to winds and allowing them to achieve far greater miss distances than were previously possible. Research and development work on guided airdrop systems has focused primarily on evolutionary improvements to the guidance algorithm, while the navigation and control algorithms have changed little since the initial autnomous systems were developed. Furthermore, the control mechanisms have not changed since the invention of the ram-air canopy in the 1960’s. The primary contributions of this dissertation are: (1) the development of a reliable and robust method to identify a flight dynamic model for a parafoil and payload aircraft using minimal sensor data; (2) the first demonstration in flight test of the ability to achieve large changes in glide slope over ground using coupled incidence angle variation and trailing edge brake deflection; (3) the first development of a control law to implement glide slope control on an autonomous system; (4) the first flight tests of autonomous landing with a glide slope control mechanism demonstrating an improvement in landing accuracy by a factor of 2 or more in especially windy conditions, and (5) the first demonstrations in both simulation and flight test of the ability to perform in-flight system identification to adapt the internal control mappings to flight data and provide dramatic improvements in landing accuracy when there is a significant discrepancy between the assumed and actual flight characteristics.

Ward, Michael

302

Implications of turbulence slope variations in different approaches  

Directory of Open Access Journals (Sweden)

Full Text Available Both heart rate variability (HRV and heart rate turbulence (HRT are established tools to study cardiac autonomic activity. Short-term studies of HRV had been reported to be stable for autonomic function assessment. However, there is little information on whether short-term HRT assessment is comparable to 24 h assessment. The aim of the study is to identify the relationship of HRT values between the 24 h and isolated tachogram measurements. We collected 24 h Holter recordings from 116 patients attending the outpatient department. HRT parameters were assessed for 24 h. Using the conventional method, HRT parameters were calculated using the average of tachograms over long-term recordings. In an alternative method, HRT parameters were obtained from each tachogram. We calculated a mean value for each subject by averaging the whole HRT data of every tachogram. Correlation analysis between the two groups of HRT values was performed. The results showed a high correlation between the two methods in turbulence slope (TS (P<0.001; r=0.84 and an extremely significant correlation in turbulence onset (TO (P<0.001; r=0.99. The values of TS were increased when assessed by separate tachogram. The variations became prominent when TS values calculated by the conventional method were low. HRT is as useful by separate tachogram assessment as by the standard Holter recordings. However, the TS values should be redefined. In subjects with abnormal turbulence slope (<2.5 calculated by averaging long-term recordings, the possibility of TS values blunted by diverse regression slope sequences in separate tachograms should be taken into consideration.

Hung Yi Chen

2011-06-01

303

Numerical simulations of dense water cascading on a steep slope  

Science.gov (United States)

Flows of dense shelf waters down the continental slope - cascades - contribute to the formation of intermediate and bottom waters and are believed to be influential in the off-shelf transport of carbon and other suspended or dissolved matter. We study cascading over steep bottom topography in numerical experiments using POLCOMS, a 3-D ocean circulation model employing a terrain-following s-coordinate system. The model setup is based on a laboratory experiment of a continuous dense water flow from a central source on a steep conical slope (39° ) in a rotating tank. The descent of the dense water mass as characterised by the length of the plume as a function of time is studied for a range of experimental parameters, mainly the density difference between plume and ambient water, the flow rate and the speed of rotation. Very good agreement between the model and the laboratory results is shown in dimensional and nondimensional variables. Our results demonstrate that a hydrostatic model is capable of reproducing the essential physics of cascading on a very steep slope if the model correctly resolves velocity veering in the bottom boundary layer. Our 3-D modelling confirms findings previously obtained by reduced physics models for a 2-layer flow. We further explore the dynamics of cascading outside of the controlled laboratory conditions in model runs where viscosity and/or diffusivity are modified. The limits of the reduced physics theory are identified in simulations with increased diffusivity where the cascade has a blurred interface between plume and ambient water and can no longer be considered a 2-layer flow. We show that downslope transport is reduced when the plume interface is strongly diffused, but enhanced in a regime that simulates cascades with increased turbulence where diffusivity and viscosity are both increased. This work was partly funded by NERC's Core Research Programme Oceans 2025 and the EU FP7 MyOceans project.

Wobus, F.; Shapiro, G. I.; Maqueda, M. A. M.; Huthnance, J. M.

2012-04-01

304

Spatio-temporal vegetation effects on slope stability  

Science.gov (United States)

The effects of tree vegetation on slope stability is well known and it is still object of research and analysis from both a modelling and quantitative point of view. However, tree vegetation has been constantly subjected to silvicultural activity either in strictly productive areas or in other more conservative areas which were meant to contrast the hydrogeological risk. From this point of view, it appears immediately important to understand the evolution resistance dynamics of root systems, which gives the possibility to correctly evaluate either the positive or negative effects of programmed cuts on woods. The aim of this work is then to try to determine which conditions are actually present and what the evolution of the mechanical characteristics of root systems (and consequently of slope stability) can be. In this purpose, we started an experimental design, by sampling and carrying out field and laboratory measurements on beech cuttings root systems. Two kinds of samples were taken into account: living beech cuttings from protected area beechwoods in order to determine the current characteristics of them and dead beech cuttings (cut in the previous years and at present in degradation) in order to have an indication of the evolution of the root mechanical characteristics. Therefore tensile strength of single roots sampled from beech stumps of plants cut in the years 2008, 2006, 2004 and 2002 at a height of about 1450 metres above sea level on SW facing slopes in High Garfagnana (a mountain in the North of Tuscany) have been also analysed. Lliving beech roots from areas at a height of 800, 1450 and 1600 metres above sea level (minimum, intermediate and maximum limit of distribution areas of local beechwoods) in a sufficient quantity as to determine the stress/strain curve have been sampled and tested, to verify if the height difference of growing areas is a factor able to influence the mechanical characteristics of living plants.

Dani, Andrea; Alliu, Ergys; Togni, Marco; Preti, Federico

2010-05-01

305

PVT Compensation for Wilkinson Single-Slope Measurement Systems  

Energy Technology Data Exchange (ETDEWEB)

A pulse-width locked loop (PWLL) circuit is reported that compensates for process, voltage, and temperature (PVT) variations of a linear ramp generator within a 12-bit multi-channel Wilkinson (single-slope integrating) Analog-to-Digital (ADC). This PWLL was designed and fabricated in a 0.5- m Silicon Germanium (SiGe) BiCMOS process. Simulation and silicon measurement data are shown that demonstrate a large improvement in the accuracy of the PVT-compensated ADC over the uncompensated ADC.

Britton Jr, Charles L [ORNL; Ericson, Milton Nance [ORNL; Blalock, Benjamin [University of Tennessee, Knoxville (UTK); Tham, Kevin [Intel Corporation; Ulaganathan, Chandradevi [University of Tennessee, Knoxville (UTK); Greenwell, Robert E [ORNL; Holleman, Jeremy [University of Tennessee, Knoxville (UTK)

2012-01-01

306

Katabatic flows over steep alpine slopes covered with short vegetation  

Science.gov (United States)

Katabatic flows are high density air flows traversing down a slope under the action of a gravitational force. These flows can be exploited for wind energy and are gaining importance in predicting scalar transport (e.g. pollutants, water vapor, CO2 drainage) within mountainous regions and in forming large cold air pools in valleys and basins. Summertime measurements over a steep slope in a narrow alpine valley (Val Ferret, Switzerland) were collected so as to explore the components of the mean longitudinal momentum balance leading to the formation of the katabatic jet. During clear-sky nights with weak synoptic forcing, observations show a strong, near-surface temperature gradient and a subsequent, weak katabatic jet with a peak velocity at less than 1 m from the surface. Two distinct log-linear layers, both in mean velocity and in temperature, characterize the katabatic jet layer (up to ~6 m) where fluxes of heat and momentum vary with height. This departure from the so-called constant-stress region typifies difficulties in modeling and predicting flows over steep topography. To circumvent some of these difficulties, a one-dimensional model for the vertical flux gradient that couples momentum and thermal balances was used to predict the mean velocity and turbulent flux profiles for katabatic flows over steep, vegetated slopes. The model predicts realistic profiles of heat and momentum fluxes in comparison with the field measurements. For example, in the case of the modeled momentum flux, the sign of the flux changes at the height of peak velocity and the higher gradient near the surface is well reproduced. It is conjectured that unsteadiness in synoptic scale conditions can be partly accommodated via a dynamic mean horizontal pressure gradient at a point. Order of magnitude calculations suggest that this term can be larger than the so-called thermal wind term when the katabatic flow is sufficiently shallow, as is the case on steep slopes. This model may serve as a test bench for various turbulent closure models that could be implemented to improve large-scale numerical weather predictions in those regions characterized by complex topography.

Oldroyd, H. J.; Katul, G. G.; Pardyjak, E.; Huwald, H.; Parlange, M. B.

2013-12-01

307

A Simple Statistic for Comparing Moderation of Slopes and Correlations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Given a linear relationship between two continuous random variables X and Y that may be moderated by a third, Z, the extent to which the correlation ? is (un)moderated by Z is equivalent to the extent to which the regression coefficients ?y and ?x are (un)moderated by Z iff the variance ratio ?y2??x2 is constant over the range or states of Z. Otherwise, moderation of slopes and of correlations must diverge. Most of the literature on this issue focuses on tests for heterogeneity of vari...

Smithson, Michael

2012-01-01

308

Ratio of slopes method for quantitative analysis in ceramic bodies  

International Nuclear Information System (INIS)

A quantitative x-ray diffraction analysis technique developed at University of Sheffield was adopted, rather than the previously widely used internal standard method, to determine the amount of the phases present in a reformulated whiteware porcelain and a BaTiO sub 3 electrochemical material. This method, although still employs an internal standard, was found to be very easy and accurate. The required weight fraction of a phase in the mixture to be analysed is determined from the ratio of slopes of two linear plots, designated as the analysis and reference lines, passing through their origins using the least squares method

1996-06-06

309

A sharp bound for the slope of double cover fibrations  

CERN Document Server

Let f: X->B be a fibred surface of genus g whose general fibre is a double cover of a smooth curve of genus gamma. We show that, for g > 4gamma+1, the number 4(g-1)/(g-gamma) is a sharp lower bound for the slope of f, proving a conjecture of Barja. Moreover, we give a characterisation of the fibred surfaces that reach the bound. In the case g = 4gamma+1 we obtain the same sharp bound under the assumption that the involutions on the general fibres glue to a global involution on X.

Cornalba, M

2005-01-01

310

Density Profile of Dense Granular Flow down a Rough Slope  

CERN Multimedia

We investigate the bulk rheology of dense granular flow down a rough slope, where the density has been found constant except for the boundary layers in simulations [Silbert {\\it et al.}, Phys. Rev. E {\\bf 64}, 051302 (2001)]. It is demonstrated that both the Bagnold scaling and the framework of kinetic theory are applicable in the bulk region, which allows us to extract the constitutive relations using simulation data. The detailed comparison of our data with the kinetic theory shows quantitative agreement for the normal and shear stresses, but there exists slight discrepancy in the energy dissipation, which causes rather large disagreement in the analysis of granular flow using the kinetic theory.

Mitarai, N; Mitarai, Namiko; Nakanishi, Hiizu

2005-01-01

311

The slope of the leading Regge trajectory in quantum chromodynamics  

International Nuclear Information System (INIS)

The Wilson loop operator in quantum chromodynamics is interpreted as a string creation operator. A method is developed to study its renormalization properties. From the QCD Heisenberg equations of motion, it is shown to satisfy a functional differential equation which linearizes in a short-range approximation. The hadron spectrum is given by the phonon spectrum of this equation, which is entirely determined by renormalization group arguments. Linear Regge trajectories are obtained, with a slope calculable in terms of the scaling violation in deep inelastic scattering due to asymptotic freedom. A remarkable numerical agreement is observed. (orig.)

1980-01-01

312

Monte-Carlo Modeling of Some Niger Delta Slope Events  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Monte-Carlo modeling has been utilized in this study to simulate seismic P-wave events on four horizons (AA, BB, CC and DD) in a Niger Delta Slope environment with the aim of generating AVO attributes. Monte-Carlo modeling undertaken on a well log from the Gulf of Mexico served as a generic model and control. Trends analysis regressions generated in the environment served as input for the models while default parameter in SAVIOR (fluid method) was used for establishing reservoir fluid p...

Oladapo, M. I.; Ojo, J. S.; Olorunfemi, M. O.; Adetola, B. A.

2009-01-01

313

Stability analysis of jointed rock slope by the block theory  

International Nuclear Information System (INIS)

The block theory to analyze three dimensional stability problems of discontinuous rock masses is applied to the actual discontinuous rock slope. Taking into consideration that the geometrical information about discontinuities generally increases according to progressive steps of rock investigation in field, the method adopted for analysis is divided into following two steps; 1) the statistical/probabilitical analysis using information from the primary investigation stage which mainly consists of that of natural rock outcrops, and 2) the deterministic analysis correspond to the secondary stage using exploration adits. (author)

1990-01-01

314

North Slope pipeline work strong; gas pipeline project deferred  

Energy Technology Data Exchange (ETDEWEB)

Over 225 miles of insulated pipelines will be installed on the North Slope as part of a 5-year, $10.5 billion program by Sohio and Arco to maintain output from the field to feed the trans-Alaska oil pipeline. New lines are for waterflood supply systems, low pressure production systems, produced water handling, and gas handling. Pipeline construction is quite active at both Prudhoe Bay and at Kuparuk Field. Future projects include an oil line to the Beaufort Sea, the Polar Gas Project, the Arctic Pilot project, and the Northern Tier Pipeline.

Hale, D.

1982-09-01

315

Slippery slopes in flat countries--a response.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In response to the paper by Keown and Jochemsen in which the latest empirical data concerning euthanasia and other end-of-life decisions in the Netherlands is discussed, this paper discusses three points. The use of euthanasia in cases in which palliative care was a viable alternative may be taken as proof of a slippery slope. However, it could also be interpreted as an indication of a shift towards more autonomy-based end-of-life decisions. The cases of non-voluntary euthanasia are a serious...

1999-01-01

316

HDMR methods to assess reliability in slope stability analyses  

Science.gov (United States)

Stability analyses of complex rock-soil deposits shall be tackled considering the complex structure of discontinuities within rock mass and embedded soil layers. These materials are characterized by a high variability in physical and mechanical properties. Thus, to calculate the slope safety factor in stability analyses two issues must be taken into account: 1) the uncertainties related to structural setting of the rock-slope mass and 2) the variability in mechanical properties of soils and rocks. High Dimensional Model Representation (HDMR) (Chowdhury et al. 2009; Chowdhury and Rao 2010) can be used to carry out the reliability index within complex rock-soil slopes when numerous random variables with high coefficient of variations are considered. HDMR implements the inverse reliability analysis, meaning that the unknown design parameters are sought provided that prescribed reliability index values are attained. Such approach uses implicit response functions according to the Response Surface Method (RSM). The simple RSM can be efficiently applied when less than four random variables are considered; as the number of variables increases, the efficiency in reliability index estimation decreases due to the great amount of calculations. Therefore, HDMR method is used to improve the computational accuracy. In this study, the sliding mechanism in Polish Flysch Carpathian Mountains have been studied by means of HDMR. The Southern part of Poland where Carpathian Mountains are placed is characterized by a rather complicated sedimentary pattern of flysh rocky-soil deposits that can be simplified into three main categories: (1) normal flysch, consisting of adjacent sandstone and shale beds of approximately equal thickness, (2) shale flysch, where shale beds are thicker than adjacent sandstone beds, and (3) sandstone flysch, where the opposite holds. Landslides occur in all flysch deposit types thus some configurations of possible unstable settings (within fractured rocky-soil masses) resulting in sliding mechanisms have been investigated in this study. The reliability indices values drawn from the HDRM method have been compared with conventional approaches as neural networks: the efficiency of HDRM is shown in the case studied. References Chowdhury R., Rao B.N. and Prasad A.M. 2009. High-dimensional model representation for structural reliability analysis. Commun. Numer. Meth. Engng, 25: 301-337. Chowdhury R. and Rao B. 2010. Probabilistic Stability Assessment of Slopes Using High Dimensional Model Representation. Computers and Geotechnics, 37: 876-884.

Kozubal, Janusz; Pula, Wojciech; Vessia, Giovanna

2014-05-01

317

Wood-soil interactions in soil bioengineering slope stabilization works  

Directory of Open Access Journals (Sweden)

Full Text Available In this work we propose the use of soil quality indicators with the aim of assessing the environmental impact of soil bioengineering works. This study was carried out in central Italy where soil bioengineering slope stabilization works were established using chestnut wood. In particular the goal of this study was to determine the occurrence of a wood-effect, that is changes of soil properties due to the presence of decomposing logs in two sites characterized by different time span since works setting up. The presence of the logs did not affect soil physico-chemical properties. Conversely, soil biochemical properties such as soil microbial biomass, basal and cumulative respiration activities as well as microbial indexes, were influenced by the presence of the logs confirming the role of these bioindicators as early predictors of changes occurring in soil. Although a general positive trend was observed for the biochemical properties at both sites with respect to the control soils, significant differences were recorded mainly at the site where works were established six years before soil sampling. Soil bioengineering slope stabilization works establish a positive feed-back which ultimately can benefit plants; in fact the increase in microbial mineralization activity can enhance nutrient cycling and thus promote adequate growth conditions for the plant cuttings used in the wooden-work.

Moscatelli MC

2009-10-01

318

Sport Injuries in Iranian Skiers (Shemshak Slope 2000-2001  

Directory of Open Access Journals (Sweden)

Full Text Available Background: Sport medicine is a relatively new scientific branch in Iran. In order to evaluate sport injuries in Iranian skiers we examined and followed all ski players who was injured while skiing in Shemshak slope during a skiing season (January to April 2000. Materials and Methods: During a period of 3 months, a total of 32050 persons skied in Shemshak slope and 76 case of injuries were identified; the injury rate was calculated as 2.3/1000 skiers. Among the injured organs knee (32% and head and neck region (20% were respectively the most common sites of injury. Sprain of the medial collateral ligament was the most frequent knee injury (28% of the cases. 26.7% of the injured cases were amateurs and 21% of them used hired ski instruments. Results: In this study such factors as lack of exercise before skiing, fatigue and time of skiing (beginning or end of the season were not found to be related to the injury rate. However, head and neck injuries in contrast to knee injuries were most frequent in the end of the season (P<0.01. Conclusion: This study confirms the necessity of greater care of knee joints during skiing and probable need of wearing helmet for head protection in the end of skiing season. More studies are necessary to clarify other details regarding sport injuries in skiers.

M Motamedy

2002-09-01

319

A Simple Statistic for Comparing Moderation of Slopes and Correlations  

Directory of Open Access Journals (Sweden)

Full Text Available Given a linear relationship between two continuous random variables $X$ and $Y$ that may be moderated by a third, $Z$, the extent to which the correlation $\\rho$ is (unmoderated by $Z$ is equivalent to the extent to which the regression coefficients $\\beta_y$ and $\\beta_x$ are (unmoderated by $Z$ iff the variance ratio $\\sigma_y^2/\\sigma_x^2$ is constant over the range or states of $Z$. Otherwise, moderation of slopes and of correlations must diverge. Most of the literature on this issue focuses on tests for heterogeneity of variance in $Y$, and a test for this ratio has not been investigated. Given that regression coefficients are proportional to $\\rho$ via this ratio, accurate tests and estimations of it would have several uses. This paper presents such a test for both a discrete and continuous moderator and evaluates its Type I error rate and power under unequal sample sizes and departures from normality. It also provides a unified approach to modeling moderated slopes and correlations with categorical moderators via structural equations models.

MichaelSmithson

2012-07-01

320

SNOW ACCUMULATION DYNAMICS ON SLOPES AND DITCHES FOR UNSOLVED GROOVE  

Directory of Open Access Journals (Sweden)

Full Text Available Statement of the problem. The problems of estimating a residual snow load capacity for unopen grooves and predicting the beginning of snow accumulation on the driveway have been discussed.Results. The mathematical model for the calculation of snow accumulation on slopes and in ditches of grooves is presented which takes into account snowfall accumulations. The balance equation for the calculation of snow accumulations in an unopen groove is suggested. The calculation formula of snow container for a typical unopen groove, which takes into account its depth is presented. The dates of full filling of unopen grooves, slopes and ditches have been predicted. The calculations are performed for typical cross-section profiles of hollow of over 1.0 m in depth.Conclusions. It has been concluded that a knowledge about snow accumulations is necessary in the calculation and predicting the beginning of snow accumulation on the driveway. The problem of a further research addressing the choice of a proper snow removal technique based on the re-sults of engineering monitoring has been discussed.

N. Yu. Alimova

2012-11-01

 
 
 
 
321

The Modeling of Slopes of Flat Roofs on Marginal Gradients  

Directory of Open Access Journals (Sweden)

Full Text Available Nagrin?jama projektuotoj?, medžiag? gamintoj? ir tiek?j? si?lomi eksploatuojam?j? stog?, skirt? automobili? stov?jimo aikštel?ms, ?rengimo variantai, pateikti Lietuvos Respublikos teis?s akt? reikalavimai šio tipo stogams. Išnagrin?ti stogo nuolydžiai ?vairiose vietose esant ribiniams stogo nuolydžiams. Parodyta, kad naudojant prilydom?sias ritinines dangas esant minimaliam nuolydžiui yra neužtikrinamas eksploatuojamo stogo patikimumas. Si?loma sugriežtinti eksploatuojam? stog? ?rengimo reikalavimus.Straipsnis lietuvi? kalbaThis article is dedicated to study installation options of roofing for parking lots which are proposed by designers, manufacturers and suppliers of materials, the Lithuanian legislative requirements for roofs of this type. Examine the roof slopes at various locations in the roof of the roof marginal gradients. It is shown that at a minimum slope of the roof the reliability of the installed roof is not provided when glued bituminous roofing membranes are used. It is proposed to raise the standards for the existing roof installations.Article in Lithuanian

Romas Rasiulis

2011-06-01

322

Estimation of streamflow by slope Regional Dependency Function  

Directory of Open Access Journals (Sweden)

Full Text Available Kriging is one of the most developed methodologies in the regional variable modeling. However, one of its drawbacks is that the influence radius can not be determined by this method. In which distance and in what ratio that pivot station is influenced from adjacent sites is rather often encountered problem in practical applications. Regional weighting functions obtained from available data consist of several broken lines. Each line has different slopes which represent the similarity and the contribution of adjacent stations as a weighting coefficient. The approach in this study is called as Slope Regional Dependency Function (SRDF. The main idea of this approach is to express the variability in value differences [?(d] and distances together. Originally proposed SRDF and Trigonometric Point Cumulative Semi-Variogram (TPCSV methods are used to predict streamflow. Also TPCSV and Point Cumulative Semi-Variogram (PCSV approaches are compared with each other. Prediction performance of all three methods stays below 10% relative error which is acceptable for the engineering applications. It is shown that SRDF outperforms PCSV and TPCSV with very high differences. It can be used for missing data completion, determination of measurement sites location, calculation of influence radius, and determination of regional variable potential. The proposed method is applied for the 38 stream flow measurement sites located in the Mississippi River basin.

A. Altunkaynak

2008-04-01

323

Estimation of streamflow by slope regional dependency function  

Directory of Open Access Journals (Sweden)

Full Text Available Kriging is one of the most developed methodologies in the regional variable modeling. However, one of its drawbacks is that the influence radius can not be determined by this method. In which distance and in what ratio that pivot station is influenced from adjacent sites is rather often encountered problem in practical applications. Regional weighting functions obtained from available data consist of several broken lines. Each line has different slopes which represent the similarity and the contribution of adjacent stations as a weighting coefficient. The approach in this study is called as Slope Regional Dependency Function (SRDF. The main idea of this approach is to express the variability in value differences ? and distances together. Originally proposed SRDF and Trigonometric Point Cumulative Semi-Variogram (TPCSV methods are used to predict streamflow. TPCSV and Point Cumulative Semi-Variogram (PCSV approaches are also compared with each other. Prediction performance of all the three methods revealed a relative error less than 10% which is acceptable for most engineering applications. It is shown that SRDF outperforms PCSV and TPCSV with very high differences. It can be used for missing data completion, determination of measurement sites location, calculation of influence radius, and determination of regional variable potential. The proposed method is applied for the 38 stream flow measurement sites located in the Mississippi River basin.

A. Altunkaynak

2008-08-01

324

Tdr Procedures for Slope Stability and Hydraulic Regime Condition Monitoring  

Science.gov (United States)

The geomorphological hazard assessment of areas heavily exposed to hydrogeological instability is dealt with the implementation of low-cost and not invasive procedures based on specific applications of TDR (Time Domain Reflectometry), which allow data on slope stability and level of soil moisture to be acquired. The proposed procedure is depicted on the implementation of an expert system for real-time monitoring of slope stability, with early warning thresholds, based on suitable geophysical surveys carried out in the study area and data acquired by a TDR network of stations appropriately placed in the territory, provided with deformation and soil moisture sensors. The acquired data and surveys will allow, however, different types of instability and main geometric and kinematic characteristics, necessary for assessing the potential damage and arranging specific risk mitigation tools to be identified. It has been provided a significant application in the city of Francavilla di Sicilia, in the province of Messina (Italy), the city with the highest level of hydrogeological vulnerability in Sicily.

Ceccio, D.; Marino, A.; Teramo, A.

2010-12-01

325

Estimating significances of differences between slopes: A new methodology and software  

Directory of Open Access Journals (Sweden)

Full Text Available Determining the significance of slope differences is a common requirement in studies of self-thinning, ontogeny and sexual dimorphism, among others. This has long been carried out testing for the overlap of the bootstrapped 95% confidence intervals of the slopes. However, the numerical random re-sampling with repetition favours the occurrence of re-combinations yielding largely diverging slopes, widening the confidence intervals and thus increasing the chances of overlooking significant differences. To overcome this problem a permutation test simulating the null hypothesis of no differences between slopes is proposed. This new methodology, when applied both to artificial and factual data, showed an enhanced ability to differentiate slopes.

Vasco M. N. C. S. Vieira

2013-09-01

326

An Extended Macroscopic Model for Traffic Flow on a Highway with Slopes  

Science.gov (United States)

In this paper, we present an extended car-following model with consideration of the gravitational force. A new macroscopic model taking into account the slope effects is developed using the relationship between the microscopic and macroscopic variables. The proposed model is applied to reflect the effect of the slope on uniform flow, traffic waves and small perturbation. The simulation results demonstrate that both the angle and the length of the slope have important impacts on traffic flow. The effect of the slope becomes more significant with the increase of the slope angle.

Chen, Jianzhong; Shi, Zhongke; Hu, Yanmei; Yu, Lei; Fang, Yuan

2013-09-01

327

Large slope instabilities in Northern Chile and Southern Peru  

Science.gov (United States)

Deep canyon incision into Tertiary paleosurfaces and large slope instabilities along the canyon flanks characterize the landscape of western slope of the Andes of northern Chile and South Peru. This area belongs to the Coastal Escarpment and Precordillera and is formed by coarse-grained clastic and volcanoclastic formations. The area is characterized by intense seismicity and long-term hyperaridity (Atacama Desert). Landslides along the canyon flanks affect volumes generally up to 1 km3 and locally evolved in large rock avalanches. We prepared a landslide inventory covering an area of about 30,000 km2, extending from Iquique (Chile) to the South and Tacna (Peru) to the North. A total of 606 landslides have been mapped in the area by use of satellite images and direct field surveys, prevalently including large phenomena. The landslides range from 1 10-3 km2 to 464 km2 (Lluta landslide). The total landslide area, inclusive of the landslide scarp and of the deposit, amounts to about 2,130 km2 (about 7% of the area). The mega landslides can be classified as large block slides that can evolve in large rock avalanches (e.g. Minimini landslide). Their initiation seems to be strongly associated to the presence of secondary faults and large fractures transversal to the slope. These landslides show evidence suggesting a re-incision by the main canyon network. This seems particularly true for the Lluta collapse where the main 'landslide' mass is masked or deleted by the successive erosion. Other landslides have been mapped along the Coastal Escarpment and some of the major tectonic escarpments with an E-W trend. We examined area-frequency distributions of landslides by developing logarithmically binned, non-cumulative size frequency distributions that report frequency density as a function of landslide planar area A. The size frequency distribution presents a strong undersampling for smaller landslides, due to the extremely old age of the inventory. For landslides larger than 2 000 m2, the distribution exhibits a power-law behaviour with scaling exponent, ?, equal to -2.24. For comparison, we analysed the power-law behaviour of other earthquake-induced landslide inventories, obtaining similar results, although the geological and seismic conditions may have been very different (Buller, New Zealand, ? = -2.42; Iningahua, New Zealand, ? = -2.53; Northridge, USA, ? = -2.39; Chi-Chi, Taiwan, ? = -2.30; Wenchuan Earthquake, China, ? = -2.19). Volume estimates and slope stability modelling have been completed to characterize the phenomena and the possible triggering mechanisms. For volume estimate, we reconstructed the pre-failure surface for tens of landslides, in order to characterize the area-volume relationship. By using this relationship, we assigned a volume to all landslides of the inventory. The study area is subject to a high seismicity associated to earthquakes of different type: interplate (superficial and intermediate depth), subduction zone earthquakes, and earthquake along the Coastal Escarpment. By analysing the frequency size relationships for earthquake-induced landslides from literature, it is possible to observe that the higher the earthquake Magnitude, the higher the frequency density curve. To quantify this observation, we used the power-law relationships derived for each inventory to calculate the frequency density associated to selected areas, and we plotted these frequencies as a function of the magnitude of the respective earthquakes. By fitting these values, we derived the expected Magnitude required to generate the landslide distribution of the study area. In conclusion, we argue that the evolution of these landslides is controlled by: deep valley incision, canyon walls undercutting and lateral migration of the river controlled by valley flank instabilities, the Presence of weak lithologies and weak basal layers, the river incision debuttressing the slope toe and especially brings to daylighting the weak basal layers observed at some landslide sites, the possible deep groundwater flow above the deep imperm

Crosta, Giovanni B.; Hermanns, Reginald L.; Valbuzzi, Elena; Frattini, Paolo; Valagussa, Andrea

2014-05-01

328

Dynamic stability and failure modes of slopes in discontinuous rock mass  

International Nuclear Information System (INIS)

The stability of rock slopes during earthquakes are of great concern in rock engineering works such as highway, dam, and nuclear power station constructions. As rock mass in nature is usually discontinuous, the stability of rock slopes will be geverned by the spatial distribution of discontinuities in relation with the geometry of slope and their mechanical properties rather than the rock element. The authors have carried out some model tests on discontinuous rock slopes using three different model tests techniques in order to investigate the dynamic behaviour and failure modes of the slopes in discontinuous rock mass. This paper describes the findings and observations made on model rock slopes with various discontinuity patterns and slope geometry. In addition some stability criterions are developed and the calculated results are compared with those of experiments. (author)

1988-01-01

329

Morphologic and sedimentologic characteristics of continental slope box slides offshore Fraser Island, Queensland, Australia  

Science.gov (United States)

The Fraser Island Slide complex is located on eastern Australia's continental slope offshore Fraser Island in southern Queensland. Morphologic, sedimentologic and geomechanical properties data for two submarine landslides, the 'North Fraser Island Upper Slope Slide' (upper slope slide) and the 'Fraser Island Middle Slope Slide' (middle slope slide) are described. Both of these features are box-shaped, slide scars from which rectangular slabs of material have been shed. The upper slope slide is situated at a water depth of approximately 750 m at the northern end of the Fraser Canyon. The head of this slide has apparently detached from a structural surface comprised of a Miocene reef complex located beneath the continental shelf edge; this slide is estimated to be 25 square kilometres in area and an average of 100m thick. The middle slope slide is situated in 1500 m of water at the southern end of the Fraser Canyon. It estimated to be 12 square kilometres in area and 50 m thick. Cores taken in the continental slope within both slides are long (upper slope 5.65 m, middle slope 3.64 m) and are dominantly comprised of hemipelagic mud. Cores taken adjacent to both slides are short (upper slope 1.33m, middle slope 0.43m) and terminate in stiff muds of suspected Miocene or Pliocene age. Additionally, the 1.33 m core on the slope adjacent to the upper slide presents a near surface layer of upper-fining of coarse to fine shelly sand which we interpret to be a turbidite deposit, this layer was deposited within hemipelagic muds which are ubiquitously present on the upper eastern Australian Continental Slope in New South Wales and Southern Queensland.

Fletcher, Melissa; Hubble, Thomas; Clarke, Samantha; Airey, David; Yu, Phyllis; Southern Surveyor V01-2013, Scientific Party RV

2014-05-01

330

Weathering-related Slope Instabilities of The Calabrian Arc (italy)  

Science.gov (United States)

Weathered igneous and metamorphic rocks widely crop out in the Mediterranean area, where in recent years greater attention has been paid to weathering-related slope movements. Calabria, the southernmost region of the Italian peninsula, is one of the most challenging area where to study such topic. Many factors favoured during past times onset and development of the weathering processes in Calabria: huge geody- namic events, still active today as proved by regional seismicity; high uplifting rate; long history of exposition to weathering agents; aggressive climatic conditions, char- acterized by intense, locally clustered, rainfall. In the late '80s a wide research pro- gramme was started in Calabria with the aim of defining an integrated, multidisci- plinary method, suitable to analyse and interpret both the weathering processes and the related instability phenomena. Two were the main goals of the research: a) the engineering-geological characteristics of weathered terrains; and b) the understanding of typology, mechanisms and triggering causes of mass movements. The research was carried out on several test sites distributed over the Calabrian Arc, a complex chain formed by several massifs (Coastal Chain, Sila, Serre, Poro, Aspromonte), largely made up of crystalline rocks. Choice of the sites was also dictated by the presence of important man-made structures (settlements, dams, tunnels, etc.) and the conse- quent availability of specific geological and geotechnical data. A summary of the re- sults so far obtained in the definition of the weathering characteristics of Calabrian crystalline rocks, in type and frequency of slope movements in weathered materials, and in the understandings of the main relations between weathering and instability as well, is here presented. In general terms, weathering in Calabria shows a complex profile, characterized by pronounced irregularity in the spatial distribution of weath- ered horizons. The latter have been recognized up to a depth of 150-200 m from the ground surface, where only occasionally fresh volumes are present. Mass movements range from slide-flows to rock instabilities, including also deep-seated phenomena. Frequency and activity of slope movements seems to be strictly related to outcropping of the more weathered horizons.

Calcaterra, D.; Parise, M.

331

Check dams effects on sediment transport in steep slope flume  

Science.gov (United States)

Depending on many influences (geology, relief, hydrology, land use, etc.) some mountainous watershed are prone to cause casualties and facilities damages. Large amounts of sediments episodically released by torrents are often the biggest problem in torrent related hazard mitigation. Series of transversal structures as check dams and ground sills are often used in the panel of risk mitigation technics. A large literature exits on check dams and it mainly concerns engineering design, e.g. toe scouring, stability stress diagram, changes in upper and lower reaches equilibrium slopes. Check dams in steep slope rivers constitute fixed points in the bed profile and prevent general bed incision. However their influence on sediment transport once they are filled is not yet clear. Two flume test campaigns, synthetize in Table 1, were performed to investigate this question: Table 1 : experiment plan Run (duration) Ref1 (50h)CD1a (30h)CD1b (30h)Ref2 (92h)CD2 (18h) Solid feeding discharge (g.s^-1) 44 44 44 60 60 Number of check dams none 1 3 none 2 A nearly 5-m-long, 10-cm-wide and 12%-steep flume was used. The water discharge was set to 0,55 l/s in all runs. A mixture of poorly sorted natural sediments with diameters between 0.8 and 40 mm was used. An open solid-discharge-feeding circuit kept the inlet sediment flux constant during all experiments. As both feeding rates did not present variation, changes in outlet solid discharge were assumed to be due to bed variations in the bed storage. We observed strong fluctuations of solid flux and slope in each reaches of all runs between: (i) steep aggradating armoured bed and (ii) less steep and finer bed releasing bedload sheets during erosion events and inducing bedload pulses. All experiments showed consistent results: transported volume associated with erosion event decreased with the length between two subsequent check dams. Solid transversal structures shorten the upstream erosion-propagation and avoid downstream change in the bed level. As long as they are not buried by too strong aggradation they allow a 'bed level independence' between reaches. On the long term, as the total inlet flux is kept constant, a decrease in transported volumes induces an increase in the erosion event frequency: sediment releases are more frequent but littler. As proposed by Poncet (1995), check dams participate efficiently in hazard mitigation because 'they release in retail what torrents would too abruptly delivered wholesale'. Reference : Poncet, A. "Restauration et conservation des terrains en montagne." Office national des forêts, Paris (1995).

Piton, Guillaume; Recking, Alain

2014-05-01

332

Predicting Modes and Displacements of Seismic Rock Slope Failures  

Science.gov (United States)

Seismically induced rock slope failures have resulted in billions of dollars of economic damage and enormous loss of life throughout the world. Accurate prediction of the triggering and run out of these failures is elusive for a variety of reasons, including knowledge of the physical modes of failure. Our research explores the potential failure modes of an idealized rigid rock block and expands the modes typically considered to include not only sliding but also toppling (pure forward rotation) and slumping (combined backward rotation and translation). The yield acceleration (or minimum inertial acceleration to cause block movement) for slumping, similar to toppling, is found to be lower than for pure translational sliding. These yield accelerations indicate the initial modes of rock block failure; however, they do not always predict the ultimate failure mode. To predict the final failure modes, the results of discrete element numerical analyses were compared to pseudo static yield acceleration to develop a seismic failure mode decision-making chart based on block geometry and interface friction. With regard to seismic displacement predictions, current simplified models predicting ultimate displacement of a mass under seismic conditions are limited to purely translating, sliding blocks (i.e. Newmark's sliding block method). Our modeling introduces additional simplified analyses to predict ultimate displacement in toppling and slumping modes as well. Important findings from these new methods are that the magnitude of seismically-induced displacement is dependent on the size of the block (or failure mass) and that as the yield acceleration decreases the seismically induced displacements increase. We plan to map these tools into analyses that evaluate rock slope systems with complex geology and geotechnical characteristics. It is envisioned that the decision chart, which predicts the initial and ultimate modes of failure based on block geometry and interface friction, and the toppling and slumping displacement models can be used to enhance seismic hazard evaluations for rock slope failure at both regional and site-specific scales. Financial support for this research was provided by the United States National Science Foundation (NSF) under grant CMMI-1156413.

Gibson, M. D.; Wartman, J.; Keefer, D. K.; Maclaughlin, M.; Arnold, L.; Applegate, K. N.; Smith, S.; Adams, S.

2013-12-01

333

Maximal slope of tensor product of Hermitian vector bundles  

CERN Document Server

We give an upper bound for the maximal slope of the tensor product of several non-zero Hermitian vector bundles on the spectrum of an algebraic integer ring. By Minkowski's theorem, we need to estimate the Arakelov degree of an arbitrary Hermitian line subbundle $\\bar M$ of the tensor product. In the case where the generic fiber of $M$ is semistable in the sense of geometric invariant theory, the estimation is established by constructing, through the classical invariant theory, a special polynomial which does not vanish on the generic fibre of $M$. Otherwise we use an explicte version of a result of Ramanan and Ramanathan to reduce the general case to the former one.

Chen, Huayi

2007-01-01

334

Transformation of an Agulhas eddy near the continental slope  

Directory of Open Access Journals (Sweden)

Full Text Available The transformation of Agulhas eddies near the continental slope of southern Africa and their subsequent self-propagation are analyzed in both observational data and numerical simulations. Self-propagation results from a net dipole moment of a generalized heton structure consisting of a surface-intensified anticyclonic eddy and deep cyclonic pattern. Such Agulhas vortical structures can form near the retroflection region and further north along the western coast of southern Africa. We analyze nonlinear topographic wave generation, vortex deformations, and filament production as an important part in water mass exchange. Self-propagating structures provide a conduit for exchange between the deep ocean and shelf regions in the Benguela upwelling system.

S. Baker-Yeboah

2010-02-01

335

Transformation of an Agulhas eddy near the continental slope  

Directory of Open Access Journals (Sweden)

Full Text Available The transformation of Agulhas eddies near the continental slope of South Africa and their subsequent self-propagation are analyzed in both observational data and numerical simulations. Self-propagation results from a net dipole moment of a generalized heton structure consisting of a surface-intensified anticyclonic eddy and deep cyclonic pattern. Such Agulhas vortical structures can form near the retroflection region and further north along the western coast of South Africa. We analyze nonlinear topographic wave generation, vortex deformations, and filament production as an important part in water mass exchange. Self-propagating structures provide a conduit for exchange between the deep ocean and shelf regions in the Benguela upwelling system.

S. Baker-Yeboah

2009-08-01

336

Biocorrosive Thermophilic Microbial Communities in Alaskan North Slope Oil Facilities  

Energy Technology Data Exchange (ETDEWEB)

Corrosion of metallic oilfield pipelines by microorganisms is a costly but poorly understood phenomenon, with standard treatment methods targeting mesophilic sulfatereducing bacteria. In assessing biocorrosion potential at an Alaskan North Slope oil field, we identified thermophilic hydrogen-using methanogens, syntrophic bacteria, peptideand amino acid-fermenting bacteria, iron reducers, sulfur/thiosulfate-reducing bacteria and sulfate-reducing archaea. These microbes can stimulate metal corrosion through production of organic acids, CO2, sulfur species, and via hydrogen oxidation and iron reduction, implicating many more types of organisms than are currently targeted. Micromolar quantities of putative anaerobic metabolites of C1-C4 n-alkanes in pipeline fluids were detected, implying that these low molecular weight hydrocarbons, routinely injected into reservoirs for oil recovery purposes, are biodegraded and provide biocorrosive microbial communities with an important source of nutrients.

Duncan, Kathleen E.; Gieg, Lisa M.; Parisi, Victoria A.; Tanner, Ralph S.; Green Tringe, Susannah; Bristow, Jim; Suflita, Joseph M.

2009-09-16

337

Investigation of a complex rock slope displacement at Brenda Mines  

Energy Technology Data Exchange (ETDEWEB)

The history and analysis of a structurally complex open-pit rock slope displacement are described. The failure involved part of the only haulage access to a major ore zone. The ongoing movement was monitored using an electric distance-measuring device and a continuous electric system specifically designed for the problem. A major fault, infilled with a thick clay gouge, and intersected by other structural features, resulted in the transfer of weight to a rock mass acting as a buttress in the lower regions. Movements were affected by blasting vibrations and ground-water conditions. Remedial measures included limiting blasting levels and lowering the water table, following which mining was successfully resumed in the area. (7 refs.)

Calder, P.N.; Blackwell, G.

1980-08-01

338

Biocorrosive thermophilic microbial communities in Alaskan North Slope oil facilities.  

Science.gov (United States)

Corrosion of metallic oilfield pipelines by microorganisms is a costly but poorly understood phenomenon, with standard treatment methods targeting mesophilic sulfate-reducing bacteria. In assessing biocorrosion potential at an Alaskan North Slope oil field, we identified thermophilic hydrogen-using methanogens, syntrophic bacteria, peptide- and amino acid-fermenting bacteria, iron reducers, sulfur/thiosulfate-reducing bacteria, and sulfate-reducing archaea. These microbes can stimulate metal corrosion through production of organic acids, CO2, sulfur species, and via hydrogen oxidation and iron reduction, implicating many more types of organisms than are currently targeted. Micromolar quantities of putative anaerobic metabolites of C1-C4 n-alkanes in pipeline fluids were detected, implying that these low molecular weight hydrocarbons, routinely reinjected into reservoirs for oil recovery purposes, are biodegraded and can provide biocorrosive microbial communities with an important source of nutrients. PMID:19921923

Duncan, Kathleen E; Gieg, Lisa M; Parisi, Victoria A; Tanner, Ralph S; Tringe, Susannah Green; Bristow, Jim; Suflita, Joseph M

2009-10-15

339

Research on the seasonal snow of the Arctic Slope  

Energy Technology Data Exchange (ETDEWEB)

This project deals with the seasonal snow on Alaska's Arctic Slope. Although it is concentrated on snow of the R{sub 4}D project area, it is important to relate the snow cover of this area with the rest of the Arctic Slope. The goals include determination of the amount of precipitation which comes as snow, the wind transport of this snow and its depositional pattern as influenced by drifting, the physical properties of the snow, the physical processes which operate in it, the proportions of it which go into evaporation, infiltration and runoff, and the biological role of the snow cover. The 1984--1985, 1985--1986 and 1986--1987 seasonal snow was measured to determine its total quantity, its physical structure and its distribution as a function of wind and topography. Observations of meteorological parameters and snowpack characteristics during winter and spring have yielded information on the seasonal evolution of the snow in quantitative terms. A method of determining melt rates over large regions was developed and is being refined, progress was made on a model describing energy flux sources which control snow melting. A strong control is exerted by air mass advection on a broad scale. We are continuing to devote attention to the sources of energy and energy transfer mechanisms which control snow melt. The 1986 snow melt was two weeks later than the 1987 and 1985 meltouts. The delay was caused by advection of cold air from the Arctic Ocean. When it did get underway melting was very rapid and the snow pack disappeared in only half the time taken in 1985.

Benson, C.S.

1988-01-01

340

Natural gas hydrates on the North Slope of Alaska  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are crystalline substances composed of water and gas, mainly methane, in which a solid-water lattice accommodates gas molecules in a cage-like structure, or clathrate. These substances often have been regarded as a potential (unconventional) source of natural gas. Significant quantities of naturally occurring gas hydrates have been detected in many regions of the Arctic including Siberia, the Mackenzie River Delta, and the North Slope of Alaska. On the North Slope, the methane-hydrate stability zone is areally extensive beneath most of the coastal plain province and has thicknesses as great as 1000 meters in the Prudhoe Bay area. Gas hydrates have been identified in 50 exploratory and production wells using well-log responses calibrated to the response of an interval in one well where gas hydrates were recovered in a core by ARCO Alaska and EXXON. Most of these gas hydrates occur in six laterally continuous Upper Cretaceous and lower Tertiary sandstone and conglomerate units; all these gas hydrates are geographically restricted to the area overlying the eastern part of the Kuparuk River Oil Field and the western part of the Prudhoe Bay Oil Field. The volume of gas within these gas hydrates is estimated to be about 1.0 {times} 10{sup 12} to 1.2 {times} 10{sup 12} cubic meters (37 to 44 trillion cubic feet), or about twice the volume of conventional gas in the Prudhoe Bay Field. Geochemical analyses of well samples suggest that the identified hydrates probably contain a mixture of deep-source thermogenic gas and shallow microbial gas that was either directly converted to gas hydrate or first concentrated in existing traps and later converted to gas hydrate. The thermogenic gas probably migrated from deeper reservoirs along the same faults thought to be migration pathways for the large volumes of shallow, heavy oil that occur in this area. 51 refs., 11 figs., 3 tabs.

Collett, T.S.

1991-01-01

 
 
 
 
341

Monte-Carlo Modeling of Some Niger Delta Slope Events  

Directory of Open Access Journals (Sweden)

Full Text Available Monte-Carlo modeling has been utilized in this study to simulate seismic P-wave events on four horizons (AA, BB, CC and DD in a Niger Delta Slope environment with the aim of generating AVO attributes. Monte-Carlo modeling undertaken on a well log from the Gulf of Mexico served as a generic model and control. Trends analysis regressions generated in the environment served as input for the models while default parameter in SAVIOR (fluid method was used for establishing reservoir fluid properties. Fourier velocity served as velocity function. The results of the modeling are presented as AVO crossplots for brine sand (background, residual hydrocarbon and commercial hydrocarbon. For each event, offset-dependent synthetic seismograms are also generated using Zoeppritz equations. The AA horizon is typified by incoherent orientations of AVO crossplots. The horizon is thus presumed unconsolidated. The synthetic seismogram generated shows no perceptible amplitude variation with offset on all the models. AVO crossplot of the encountered BB horizon show that most of the commercial hydrocarbon plots and some of the residual hydrocarbon plots fall on quadrant III (bright spot quadrant. Synthetic seismic generated for BB horizon exhibits positive AVO response (soft kick on the commercial hydrocarbon model. A similar but marginal response was obtained on brine saturated BB model. Brine saturated model of the AVO crossplot for CC horizon model plotted mostly on hard sand quadrant. Conversely, presumed commercial hydrocarbon saturated CC is split between the hard sand and soft sand quadrants with low background normal values. The DD horizon is similar to the deep model of the Gulf of Mexico and hence exhibits similar crossplot. Curiously, high background normal (Bn characterized residual hydrocarbon models while unconsolidated gas sand horizons exhibit anomalous characteristics. The AVO crossplot obtained from the Monte-Carlo model could be a robust tool for mapping reservoirs within the Niger Delta Slope.

M.I. Oladapo

2009-01-01

342

The slope seismic response monitoring of Wenchuan aftershocks in Qingchuan  

Science.gov (United States)

This work reports some new progress of rock slope inside seismic response monitoring results in the area of Mountain Dong and Mountain Shizi (Qingchuan county), located more than 250 km NE of Yingxiu epicenter (2008 Wenchuan earthquake), Sichuan province. Five adits with the maximum depth of 15 m had been excavated in different elevation on both sides slope. Stations were emplaced at middle of the adits, from September 2009 to May 2010 more than 60 Wenchuan aftershocks had been monitored, 22 typical aftershocks had been analysis, whose magnitude varied between 2.3 ~ 5.2 and epicentral distance was from a few to 45 km. A comparison analysis of recordings provided evidence of the presence amplification effect at the Q4 station of Mt. Dong, which the peak horizontal acceleration amplification factor is between 1.0 ~ 2.5. But this amplification effect had no stronger at other stations. Comprehensive studies show that the relative height to riverbed is an important factor of Q4 seismic amplification effect. Otherwise the topography of Q4 site is conducive to horizontal amplification, not the vertical amplification. Moreover the calculation of Arias intensity (Ia) had the same amplification effect as the PGA, only the amplification factor is between 1.0 ~ 3.47 much bigger than the latter. On the other hand, the calculation of horizontal to vertical spectral ratio (HVSR) at Q4 shows the curves have multiple peaks corresponding with different dominant frequencies, which the amplification factor is always bigger than other stations at Mt. Dong. Sufficient evidence indicates that the Mt. Dong amplification effect is stronger than Mt. Shizi.

Luo, Y. H.; Huang, R.; Wang, Y.

2014-06-01

343

A streamwise view of the Norwegian Atlantic Slope Current  

Science.gov (United States)

The inflow to the Arctic Ocean and the Barents Sea is mainly constituted by water carried poleward by the Norwegian Atlantic slope current (NwASC). This barotropically locked shelf-edge current plays a major role in linking the North-Atlantic to the Arctic. Based on an almost 20-year satellite altimetry record and a strictly isobath-following geostrophic approach, we provide a detailed large-scale view of the NwASC, here defined as extending from the Faroe-Shetland Channel (FSC) up to Bjørnøya at the Barents Sea opening (BSO). The study is initiated by examining current-meter data and isobath-following barotropic transport at three locations along the NwASC; Svinøy, Gimsøy and Bjørnøya. This inter-comparison yielded a good agreement, confirming the robustness of the altimetric along-isobath approach. The analysis is continued by decomposing the NwASC into a number of regions (FSC, Svinøy, Vøring, Lofoten and BSO) and conducting a probability-density (PD) analysis of their transports. In general, the southern regions show a broad range of transport variability (wide PD distribution), while the northern distributions are narrow. The southern distributions are most likely influenced by the large-scale exchange in the Nordic Seas, while the northern distributions are to a large extent caused by the steep bottom topography capable of stabilizing the flow. The transports are further discussed in relation to the isobath-following eddy kinetic energy (EKE) in the different regions. The most interesting relationship is found at the Lofoten slope, where the EKE appears to be extremely sensitive to increases of the barotropic transport (which has little variability). This has implications for how flow as well as hydrographic anomalies might be transferred through the Nordic Seas toward the Arctic, where intense eddy shedding in the Lofoten region appears to curtail these signals.

Chafik, Léon; Nilsson, Johan; Skagseth, Øystein

2013-04-01

344

Short-term vegetation recovery after a spring grassland fire in Lithuania. Effect of time and slope position  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this work is study the effects of a grassland fire in vegetation recuperation according to fire severity, slope exposition and position. We designed two experimental plots, one located in an east faced slope (Slope A and other in a west faced (Slope B. Vegetation recuperation was assessed 10, 17, 31 and 46 days after the fire. The results showed that fire severity was higher in slope B, than in slope A. In both slopes vegetation recuperation was different according position. Bottom positions recovered faster than slope and upslope positions, that it is attributed to fire severity (higher in slope and upslope areas and ash and soil transport and deposition in bottom areas. The vegetation recuperated faster in slope B and 46 days after the fire, 100% of the plot was covered. This was attributed to higher severity, more complex topography, and inclination of Slope A, that delayed the vegetation recover.

P. Pereira

2013-01-01

345

Analytical basis for determining slope lines in grid digital elevation models  

Science.gov (United States)

An analytical basis for the determination of slope lines in grid digital elevation models is provided by using the D8-LTD method (eight slope directions, least transverse deviation). The D8-LTD method's capability to predict consistently exact slope lines as the grid cell size goes to zero is shown analytically by applying mathematical analysis methods. The use of cumulative, least transverse deviations is found to be the key factor allowing for globally unbiased approximations of slope lines. The D8-LTD method's properties are also demonstrated numerically by using digital elevation models of a synthetic sloping surface obtained from the Himmelblau function. It is shown that slope lines obtained from the D8-LTD method can approximate the exact slope lines as close as desired by selecting a grid cell size that is small enough. In contrast, the standard D8 method is found to produce significantly biased results even when small grid cells are used. The D8-LTD method outperforms the D8 method over a wide range of grid cell sizes (up to 20 m in this application), beyond which grid cell size becomes too large to validly represent the underlying sloping surface. It is therefore concluded that the D8-LTD method should be used in preference to the standard D8 method in order to obtain slope lines that are only limited in reliability by the detail of topographic data, and not by the accuracy of the slope direction method applied.

Orlandini, Stefano; Moretti, Giovanni; Gavioli, Andrea

2014-01-01

346

A study of the surface energy balance on slopes in a tallgrass prairie  

Science.gov (United States)

Four slopes (north, south, east, and west) were selected on the Konza Prairie Research Natural Area to study the effect of topography on surface energy balance and other micrometeorological variables. Energy fluxes, air temperature, and vapor pressure were measured on the sloped throughout the 1988 growing season. Net radiation was the highest on the south-facing slope and lowest on the north-facing slope, and the difference was more than 150 W/sq m (20 to 30 percent) at solar noon. For daily averages, the difference was 25 W/sq m (15 percent) early in the season and increased to 60 W/sq m (30 to 50 percent) in September. The east-facing and west-facing slopes had the same daily average net radiation, but the time of day when maximum net radiation occurred was one hour earlier for the east-facing slope and one hour later for the west-facing slope relative to solar noon. Soil heat fluxes were similar for all the slopes. The absolute values of sensible heat flux (h) was consistently lower on the north-facing slope compared with other slopes. Typical difference in the values of H between the north-facing and the south-facing slopes was 15 to 30 W/sq m. The south-facing slope had the greatest day to day fluctuation in latent heat flux as a result of interaction of net radiation, soil moisture, and green leaf area. The north-facing slope had higher air temperatures during the day and higher vapor pressures both during the day and at night when the wind was from the south.

Nie, D.; Demetriades-Shah, T.; Kanemasu, E. T.

1990-01-01

347

Slope aspect modifies community responses to clear-cutting in boreal forests.  

Science.gov (United States)

Slope aspect modifies microclimate and influences ecological processes and spatial distribution of species across forest landscapes, but the impact of slope aspect on community responses to disturbance is poorly understood. Such insight is necessary to understand landscape community dynamics and resilience. We compared bryophyte (liverworts and mosses) communities in matched 0.02-ha plots of four boreal stand types in central Sweden: recently clear-felled and mature stands dominated by Norway spruce in south-facing and north-facing slopes. Differences between forests and clear-cuts were interpreted as effects of clear-cutting, and differences between south- and north-facing slopes as effects of aspect. In response to clear-cutting, bryophyte cover and composition changed more in south-facing slopes. Only one out of ten significantly declining species in south-facing slopes also declined significantly in north-facing slopes. North-facing slopes lost fewer bryophyte species, and among those, fewer forest species and fewer species associated with wood and bark. In north-facing slopes, the average proportions of mosses and liverworts shared between the forest and the clear-cut plot were 88% and 74%, respectively. Corresponding numbers for south-facing slopes were 79% and 33%. In addition, more bryophyte species were added in north- than south-facing slopes after clear-cutting, somewhat reducing the difference in compositional change between aspects. South- and north-facing mature forests differed in species composition, mostly due to higher richness of mosses in south-facing slopes. The smaller changes in bryophyte communities on north-facing slopes in response to clear-cutting have implications for ecosystem dynamics and management as high local survival may enhance landscape-level resilience. PMID:17503602

Aström, Marcus; Dynesius, Mats; Hylander, Kristoffer; Nilsson, Christer

2007-03-01

348

The slope-background for the near-peak regimen of photoemission spectra  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •We propose a method that accounts for the change in the background slope of XPS data. •The slope-background can be derived from Tougaard–Sigmund's transport theory. •The total background is composed by Shirley–Sherwood and Tougaard type backgrounds. •The slope-background employs one parameter that can be related to REELS spectra. •The slope, in conjunction with the Shirley–Sherwood background, provides better fits. -- Abstract: Photoemission data typically exhibits a change on the intensity of the background between the two sides of the peaks. This step is usually very well reproduced by the Shirley–Sherwood background. Yet, the change on the slope of the background in the near-peak regime, although usually present, is not always as obvious to the eye. However, the intensity of the background signal associated with the evolution of its slope can be appreciable. The slope-background is designed to empirically reproduce the change on the slope. Resembling the non-iterative Shirley method, the proposed functional form relates the slope of the background to the integrated signal at higher electron kinetic energies. This form can be predicted under Tougaard–Sigmund's electron transport theory in the near-peak regime. To reproduce both the step and slope changes on the background, it is necessary to employ the slope-background in conjunction with the Shirley–Sherwood background under the active-background method. As it is shown for a series of materials, the application of the slope-background provides excellent fits, is transparent to the operator, and is much more independent of the fitting range than other background methods. The total area assessed through the combination of the slope and the Shirley–Sherwood backgrounds is larger than when only the Shirley–Sherwood background is employed, and smaller than when the Tougaard background is employed.

Herrera-Gomez, A., E-mail: aherrera@qro.cinvestav.mx [CINVESTAV-Unidad Queretaro, Queretaro 76230 (Mexico); Bravo-Sanchez, M. [CINVESTAV-Unidad Queretaro, Queretaro 76230 (Mexico); Aguirre-Tostado, F.S. [Centro de Investigación en Materiales Avanzados, Chihuahua, Chihuahua 31109 (Mexico); Vazquez-Lepe, M.O. [Departamento de Ingeniería de Proyectos, Universidad de Guadalajara, Jalisco 44430 (Mexico)

2013-08-15

349

Small slope tilts caused by meteorological effects and vital processes of trees on a wooded slope in Hidegvíz Valley, Hungary  

Science.gov (United States)

Long-term measurements were carried out to investigate the relationship between ground tilts and variations of meteorological (temperature, precipitation) and hydrological (soil moisture content) parameters in the area of the Sopron Mountains, on a wooded slope of the Hidegvíz Valley, Hungary. The connection between surface tilts and the vital processes of the trees was also studied on the basis of the reference evapotranspiration calculated for the study area. Long- and short-term variations were separated. A long-term ground temperature change of 1 °C caused a 4 ?rad tilt in the SE direction. Short-term temperature effects can be neglected. The fluctuation of temperature around the freezing point caused tilts of about 10 ?rad °C- 1. The soil water content variation had the largest effect on the ground tilt (0.5 ?rad mm- 1). Its contribution to the total ground tilt in the investigated period was about 70 ?rad (65% of the total tilt of 107 ?rad) toward the SSE. The contribution of the wind speed to the ground tilt was about 20 ?rad m s- 1 toward the SSE depending on the water content of the soil. The wind did not cause a permanent ground tilt. The magnitude of the daily tilt variations in the active growing period of trees, from March to October, is 1-2 ?rad while in the dormant period (with no canopy) the tilt variations were less than 0.4 ?rad. The admittances between the evapotranspiration and the ground tilts were 0.3-0.5 ?rad mm- 1 and 0.1-0.2 ?rad mm- 1 in the active and dormant period of the trees, respectively. These small effects superimposed on each other can significantly contribute to slope failures. The results of this study provide information which can be useful in the modelling of landslide movements and for the mitigation of landslide hazards.

Mentes, Gyula; Bódis, Virág Bereniké; Vig, Péter

2014-02-01

350

Finite Element Analysis for Bearing Capacity of Rectangular Footing Resting Near Sloped Cohesive soil  

Directory of Open Access Journals (Sweden)

Full Text Available Finite element method is used to investigate the ultimate bearing capacity of rectangular footing resting on cohesive soil near slope. The effect of footing aspect ratio (L/B, distance ratio (b/B, and slope angle (? on the bearing capacity are calculated. A new reduction factor (Rs is proposed to compute the ultimate bearing capacity for rectangular footing adjacent to slope of cohesive soil from ultimate bearing capacity for similar rectangular footing resting on ground level of cohesive soils. This study shows that the ultimate bearing capacity for rectangular footing adjacent to slope of cohesive soils decreases when slope angle (? and aspect ratio (L/B increases.  Also the ultimate bearing capacity increases when the distance ratio (b/B increases. Finally The effect of slope diminishes as the distance ratio (b/B equal, or exceeds 0.75.

Jawdat K. Abbas

2013-04-01

351

Using Social Information to Guide Action: Infants' Locomotion Over Slippery Slopes  

Science.gov (United States)

In uncertain situations such as descending challenging slopes, social signals from caregivers can provide infants with important information for guiding action. Previous work showed that 18- month-old walking infants use social information selectively, only when risk of falling is uncertain. Experiment 1 was designed to alter infants’ region of uncertainty for walking down slopes. Slippery Teflon-soled shoes drastically impaired 18-month-olds’ ability to walk down slopes compared with walking barefoot or in standard crepe-soled shoes, shifting the region of uncertainty to shallower range of slopes. In Experiment 2, infants wore Teflon-soled shoes while walking down slopes as their mothers encouraged and discouraged them from walking. Infants relied on social information on shallow slopes, even at 0°, where the probability of walking successfully was uncertain in the Teflon-soled shoes. Findings indicate that infants’ use of social information is dynamically attuned to situational factors and the state of their current abilities.

Adolph, Karen E.; Karasik, Lana B.; Tamis-LeMonda, Catherine S.

2010-01-01

352

LogN-logS slope determination in imaging X-ray astronomy  

Science.gov (United States)

The problem of estimating the slope of the number-counts relations for the specific case of imaging X-ray surveys is briefly discussed. Results have been obtained from extensive simulations of Einstein Observatory imaging X-ray data. It is concluded that the bias which affects the X-ray number-counts slope determination is much smaller than that which affects the radio number-counts slope.

Maccacaro, Tommaso; Romaine, Suzanne; Schmitt, H. M. M.

1987-01-01

353

Protection Roles of Gleditshia Caspica Dsf. on Slopes in Iran  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Slope instability due to landslides is particularly common in N Iran. It is possible to fight against these hazards thanks to the roots of scrubs, which provide an important contribution towards the stability of hillslopes. However, knowledge on the effectiveness of roots for slope stability needs improvement. Therefore, a study has been carried out on the effect of roots on slope stability, in particular for Gleditshia sp. The study area was located in Roudsar Township, in...

2007-01-01

354

The impact of graph slope on rate of change judgments in corporate reports  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The use of graphs to disclose financial information in annual reports represents a significant dimension of financial disclosure management. Statistical graphics studies demonstrate that the accurate visual decoding of a graph is contingent upon the graph's slope parameter. This article reports two related studies into the slope parameter in a financial reporting context. A laboratory experiment indicates that sub-optimal slope parameters produce distorted judgments of corporate performance a...

2002-01-01

355

A new GTD slope diffraction coefficient for plane wave illumination of a wedge  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two wedge problems including slope diffraction are solved: one in which the incident field is a non-uniform plane wave, and one in which it is an inhomogeneous plane wave. The two solutions lead to the same GTD slope diffraction coefficient. This coefficient reveals the existence of a coupling effect between a transverse magnetic (or transverse electric) incident plane wave and the transverse electric (or transverse magnetic) slope-diffracted field. The coupling effect is not described by the...

2006-01-01

356

Deformation monitoring and modeling based on LiDAR data for slope stability assessment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Time dependent deformation is a common process in soil slopes but never the less a challenging task for stability assessment. Slope failure and the land subsidence originating not only from extensive constructions and mining but also due to geological processes are common problems, which adversely influence environment, human safety and economic development. In order to pursue an advanced methodology for management and mitigation of soil slope failure, such points as adequate monitoring techn...

Hu, Hui

2013-01-01

357

Problems of definitive slopes mining at Doly Nástup Tušimice  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The instability of slopes influents mining business in many aspects at opencast mining. The temporary decrease of intended mined volumes due to landslips is common and sometimes there is necessary to change origin-mining plans. It has impact to economy and other essential costs for rehabilitation are required. In case of definitive slopes formation in contact to traffic and communication networks, watercourses and infrastructures of seats stability of slope security there is even more importa...

2007-01-01

358

Alaska North Slope regional gas hydrate production modeling forecasts  

Science.gov (United States)

A series of gas hydrate development scenarios were created to assess the range of outcomes predicted for the possible development of the "Eileen" gas hydrate accumulation, North Slope, Alaska. Production forecasts for the "reference case" were built using the 2002 Mallik production tests, mechanistic simulation, and geologic studies conducted by the US Geological Survey. Three additional scenarios were considered: A "downside-scenario" which fails to identify viable production, an "upside-scenario" describes results that are better than expected. To capture the full range of possible outcomes and balance the downside case, an "extreme upside scenario" assumes each well is exceptionally productive.Starting with a representative type-well simulation forecasts, field development timing is applied and the sum of individual well forecasts creating the field-wide production forecast. This technique is commonly used to schedule large-scale resource plays where drilling schedules are complex and production forecasts must account for many changing parameters. The complementary forecasts of rig count, capital investment, and cash flow can be used in a pre-appraisal assessment of potential commercial viability.Since no significant gas sales are currently possible on the North Slope of Alaska, typical parameters were used to create downside, reference, and upside case forecasts that predict from 0 to 71??BM3 (2.5??tcf) of gas may be produced in 20 years and nearly 283??BM3 (10??tcf) ultimate recovery after 100 years.Outlining a range of possible outcomes enables decision makers to visualize the pace and milestones that will be required to evaluate gas hydrate resource development in the Eileen accumulation. Critical values of peak production rate, time to meaningful production volumes, and investments required to rule out a downside case are provided. Upside cases identify potential if both depressurization and thermal stimulation yield positive results. An "extreme upside" case captures the full potential of unconstrained development with widely spaced wells. The results of this study indicate that recoverable gas hydrate resources may exist in the Eileen accumulation and that it represents a good opportunity for continued research. ?? 2010 Elsevier Ltd.

Wilson, S. J.; Hunter, R. B.; Collett, T. S.; Hancock, S.; Boswell, R.; Anderson, B. J.

2011-01-01

359

78 FR 38358 - Call for Nominations: North Slope Science Initiative, Science Technical Advisory Panel, Alaska  

Science.gov (United States)

...North Slope traditional and local knowledge, landscape ecology, petroleum engineering, civil engineering, geology, sociology, cultural anthropology, economics, ornithology, oceanography, fisheries, marine biology, landscape ecology, and...

2013-06-26

360

Efficiency of Timber Jack 450C with Different Loading Volumes in Different Slopes  

Directory of Open Access Journals (Sweden)

Full Text Available Primary transportation is an upper time, expensive and hard labour. The most skidding are with using of rubber wheel of Timber jack 450C in Iran country that has devoted 60% of utilization expenses. In order to, investigate of slope and loading volume effects on time of loaded traveling had used time study for Timberjack 450C. In one of strip roads in parcel eleven of district two of Langa management plan forest (Kelardasht region in North of Iran determined 5 and 3 different slopes classes and volumes classes, respectively. Then, time study was performed in slope classes with different loading volume in downward skidding. The first, collection of data have noted in special form and then have converted to uniform unit of m sec-1. Descriptive statistics for each data set were calculated using the SPSS software. With presupposition that loading volume and slope are effective on the obtained time, these parameters have analyzed. ANOVA and Tukey test were used for loading volume factor. For investigation slope factor had used of Mann Whitney non-parametric test in order to comparison of loaded traveling speed in different slopes. Results of present research had showed that influence of loading volume on the loaded traveling time is insignificant, but loaded traveling speed in different slope classes is significant (in slopes >30% as, speed of skidder machine is decreased with increase of slope variable.

Majid Lotfalian

2007-01-01

 
 
 
 
361

Geotechnical study and optimum pit slope design of the Ashok coal opencast project  

Energy Technology Data Exchange (ETDEWEB)

The paper deals with the geotechnical study and optimum ultimate pit slope design of Ashok opencast project with special reference to the highwalls ability of slopes created by surface miner. It was also aimed to know the influence of slope design parameters on the safety factor by sensitivity analysis. Geotechnical mapping was done on the exposed benches of the surface mine as per the norms of International Society of Rock Mechanics. The different geomechanical properties of lithological units were determined. The failure analysis was done by GALENA software based on limit equilibrium method and optimum slope design was recommended. 2 refs., 5 figs., 4 tabs.

Singh, V.K. [Central Institute of Mining and Fuel Research, Dhanbad (India)

2008-03-15

362

Examination of composite enamel layer systems by ion beam slope cutting  

International Nuclear Information System (INIS)

A non-mechanical, new method of sample preparation - the ion beam slope cutting - is presented. On the basis of a mechanically produced ground plane illustrating the composite enamel interface on an extracted free from caries tooth in usual manner a defined slope is made at an angle of 45 degrees to the interface by means of inert gas ions over a diaphragm. The resulting slope plane is neither mechanically deformed nor directly influenced by ions. First examination results (SEM) allow to draw conclusions about filler construction, defective adhesion and cohesive defects. The ion beam slope cutting is a completion of examination possibilities. (author)

1988-01-01

363

Probabilistic model of slope mass movement susceptibility – a case study of Bovec municipality, Slovenia  

Directory of Open Access Journals (Sweden)

Full Text Available A probabilistic model of slope mass movement susceptibility for the Bovec municipality in north-western Slovenia was developed based on the expert geohazard map at scale 1: 25.000 and several other relevant influence factors. For analytical purposes 10816 modelswere developed, 3142 for landslide susceptibility and 7674 for rockfall susceptibility. In both cases geology / lithology and slope angle showed to be the most important influence factors. Regarding landslides, additional important factors were land use and synchronismof strata bedding and slope aspect, and in the case of rockfalls additional important factor was synchronism of strata bedding and slope aspect.

Marko Komac

2005-12-01

364

Landscape design of slope works in dam construction; Damu ni okeru norimen to sono keikan taisaku  

Energy Technology Data Exchange (ETDEWEB)

While the construction of a dam is progressing, many slopes appear in association with various dam construction works such as the dam proper, temporary facilities, removal of surplus soil, road shifting, etc.. Regarding these slopes, it is important to take into account the surrounding environment and landscape, and take positive measures for creation of the excellent dam space, while studying carefully on how to secure rationality and stability of the scale, configuration, etc.. In this report, taking into consideration the above points, the basic problems and rules of slopes associated with the dam construction, the concepts and examples regarding the environmental and landscape measures for the slopes of a reservoir, business sites, etc. are introduced. Basically in order to handle the slopes appearing from the dam construction, the guide for slope works of road construction and stabilization works of slopes is referred to. As the basic problems, there are formation of long slopes, changes of conditions during execution, effects on the environment and landscape, etc.. Regarding the natural conditions concerning slope design, there are three, namely topography, geology and environment/landscape, and it is necessary to investigate well and judge them from the overall viewpoint of stability, economy and environmental/landscape quality. 10 refs., 7 figs.

Deguchi, S.; Hirano, I. [Water Resources Development public Corp., Tokyo (Japan)

1996-06-01

365

Judgments of visually perceived eye level (VPEL) in outdoor scenes: effects of slope and height.  

Science.gov (United States)

When one looks up a hill from below, its peak appears lower than it is; when one looks at a hill across a valley from another peak, the peak of that hill appears higher than it is. These illusions have sometimes been explained by assuming that the subjective horizontal is assimilated to the nearby slope: when looking up a slope, the subjective horizontal is raised, diminishing the height of the peak above the subjective horizontal, and making the peak appear lower than it is. When looking down a slope towards another hill, the subjective horizontal is lowered, increasing the height of that hill above the subjective horizontal, and making its peak appear higher than it is. To determine subjective horizontals we measured visually perceived eye levels (VPELs) in 21 real-world scenes on a range of slopes. We found that VPEL indeed assimilates by about 40% to slopes between 7 degrees downhill and 7 degrees uphill. For larger uphill slopes up to 23 degrees, VPEL asymptotes at about 4.5 degrees. For larger downhill slopes, the assimilation of VPEL diminishes, and at 23 degrees is raised by about 1 degree. These results are consistent with the assimilation explanation of the illusions if we assume that steep downhill slopes lose their effectiveness by being out of view. We also found that VPEL was raised when viewing from a height, in comparison with ground-level views, perhaps because the perceived slope increases with viewing height. PMID:17972481

O'Shea, Robert P; Ross, Helen E

2007-01-01

366

Asynchronism effect of cell population on the initial slope of dose-effect curve  

International Nuclear Information System (INIS)

The presence of the initial slope both for survival and dose curves and mutation inductions under the effect of various radiation types, is proved. It is established that the initial slope of the survival curve is proportional to the dose in all types of ionizing radiations, and its value changes regularly depending on the cell position in the cycle. In the case of asynchronous cell population, the initial slope of the survival curve can be determined by the most sensitive cells. The estimation of the value of this slope by studying cell survival can be rather difficult

1974-09-21

367

Degree of adversity of discontinuity orientation in relation to rock slope instability: Earth and Environment  

...Degree of adversity of discontinuity orientation in relation to rock slope instability: Earth and Environment Faculty of Environment Leeds.ac.uk Portal Site ...Multiphase Flow Laboratory Degree of adversity of discontinuity orientation in relation to rock slope instability PI: Dr. Bill Murphy CI: Dr....Research Project Title: Degree of adversity of discontinuity orientation in relation to rock slope instability Project Overview: This research aims to investigate strength ...anisotropy and how it mobilises in rock masses associated with slope failure by performing limit equilibrium and finite element method analysis on selected landslides,...

368

A new GTD slope diffraction coefficient for plane wave illumination of a wedge  

DEFF Research Database (Denmark)

Two wedge problems including slope diffraction are solved: one in which the incident field is a non-uniform plane wave, and one in which it is an inhomogeneous plane wave. The two solutions lead to the same GTD slope diffraction coefficient. This coefficient reveals the existence of a coupling effect between a transverse magnetic (or transverse electric) incident plane wave and the transverse electric (or transverse magnetic) slope-diffracted field. The coupling effect is not described by the existing GTD slope diffraction coefficient

Lumholt, Michael; Breinbjerg, Olav

1997-01-01

369

Sub-microradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler  

Energy Technology Data Exchange (ETDEWEB)

A new low budget slope measuring instrument, the Developmental Long Trace Profiler (DLTP), was recently brought to operation at the ALS Optical Metrology Laboratory. The design, instrumental control and data acquisition system, initial alignment and calibration procedures, as well as the developed experimental precautions and procedures are described in detail. The capability of the DLTP to achieve sub-microradian surface slope metrology is verified via cross-comparison measurements with other high performance slope measuring instruments when measuring the same high quality test optics. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.

Yashchuk, Valeriy V; Barber, Samuel; Domning, Edward E.; Kirschman, Jonathan L.; Morrison, Gregory Y.; Smith, Brian V; Siewert, Frank; Zeschke, Thomas; Geckeler, Ralf; Just, Andreas

2009-09-11

370

Sub-microradian surface slope metrology with the ALS Developmental Long Trace Profiler  

International Nuclear Information System (INIS)

A new low-budget slope measuring instrument, the Developmental Long Trace Profiler (DLTP), was recently brought to operation at the ALS Optical Metrology Laboratory. The design, instrumental control and data acquisition system, initial alignment and calibration procedures, as well as the developed experimental precautions and procedures are also described in detail. The capability of the DLTP to achieve sub-microradian surface slope metrology is verified via cross-comparison measurements with other high-performance slope measuring instruments when measuring the same high-quality test optics. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.

2010-05-01

371

Slope heuristics for heteroscedastic regression on a random design  

CERN Multimedia

In a recent paper Birg\\'e and Massart (2006) have introduced the notion of minimal penalty in the context of penalized least squares for Gaussian regression. They have shown that for several model selection problems, simply multiplying by 2 the minimal penalty leads to some (nearly) optimal penalty in the sense that it approximately minimizes the resulting oracle inequality. Interestingly, the minimal penalty can be evaluated from the data themselves which leads to a data-driven choice of the penalty that one can use in practice. Unfortunately their approach heavily relies on the Gaussian nature of the stochastic framework that they consider. Our purpose in this paper is twofold: stating a heuristics to design a data-driven penalty (the slope heuristics) which is not sensitive to the Gaussian assumption as in (Birg\\'e and Massart, 2006) and proving that it works for penalized least squares random design regression. As a matter of fact, we could prove some precise mathematical results only for histogram bin-wi...

Arlot, Sylvain

2008-01-01

372

Lateral loading on piles due to slope instability  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the Caripito Oil Loading Terminal case history for which very flat slope instability was responsible for the failure and structural collapse of seven mooring and/or breasting dolphins, plus the collapse of all of the intermediate supports of catwalk bridges that provide access to the dolphins, from or to the loading platforms. These supports collapsed before the dolphins did as, in the whole, they were much weaker to support lateral thrusts, even though they were strengthened with additional piles, on several occasions. When movement of the dolphins first became apparent, a monitoring program was designed to measure the displacement of the pile caps. The primary cause for failure was the very weak nature of the subsoil, but the triggering mechanism was the need to dredge the bottom, further than previously in the past, because of the new recent condition of siltation and sedimentation and to accommodate larger tankers with larger draughts. Although most of the dolphins failed in a three year period, the trestles and the loading platforms have not shown, so far, significant signs of distress. This paper deals with the site assessment program, with what caused the failures, how the collapse occurred and the conclusions, that were drawn during the study.

Lupini, J.F.; Chacin, M.E.; Furiol, A.; Troconis, C.M.; Vargas, F.

1995-12-01

373

Linear error analysis of slope-area discharge determinations  

Science.gov (United States)

The slope-area method can be used to calculate peak flood discharges when current-meter measurements are not possible. This calculation depends on several quantities, such as water-surface fall, that are subject to large measurement errors. Other critical quantities, such as Manning's n, are not even amenable to direct measurement but can only be estimated. Finally, scour and fill may cause gross discrepancies between the observed condition of the channel and the hydraulic conditions during the flood peak. The effects of these potential errors on the accuracy of the computed discharge have been estimated by statistical error analysis using a Taylor-series approximation of the discharge formula and the well-known formula for the variance of a sum of correlated random variates. The resultant error variance of the computed discharge is a weighted sum of covariances of the various observational errors. The weights depend on the hydraulic and geometric configuration of the channel. The mathematical analysis confirms the rule of thumb that relative errors in computed discharge increase rapidly when velocity heads exceed the water-surface fall, when the flow field is expanding and when lateral velocity variation (alpha) is large. It also confirms the extreme importance of accurately assessing the presence of scour or fill.

Kirby, W. H.

1987-12-01

374

On the Density profile slope of Clusters of Galaxies  

CERN Multimedia

The present paper extends to clusters of galaxies the study of Del Popolo (2012), concerning how the baryon-dark matter (DM) interplay shapes the density profile of dwarf galaxies. Cluster density profiles are determined taking into account dynamical friction, random and ordered angular momentum and the response of dark matter halos to condensation of baryons. We find that halos containing only DM are characterized by Einasto's profiles, and that the profile flattens with increasing content of baryons, and increasing values of random angular momentum. The analytical results obtained in the first part of the paper were applied to well studied clusters whose inner profiles have slopes flatter than NFW predictions (A611, A383) or are characterized by profiles in agreement with the NFW model (MACS J1423.8+2404, RXJ1133). By using independently-measured baryonic fraction, a typical spin parameter value $\\lambda \\simeq 0.03$, and adjusting the random angular momentum, we re-obtain the mass and density profiles of t...

Del Popolo, A

2012-01-01

375

Material-Point-Method Analysis of Collapsing Slopes :  

DEFF Research Database (Denmark)

To understand the dynamic evolution of landslides and predict their physical extent, a computational model is required that is capable of analysing complex material behaviour as well as large strains and deformations. Here, a model is presented based on the so-called generalised-interpolation material-point method, combining a Eulerian grid for solving the governing equations of a continuum with a Lagrangian description for the material. The method is extended to analyse interaction between multiple bodies, introducing a master-slave algorithm for frictional contact along interfaces. Further, a deformed material description is introduced, based on time integration of the deformation gradient and utilising Gauss quadrature over the volume associated with each material point. The method has been implemented in a Fortran code and employed for the analysis of a landslide that took place during the night of December 1st, 2008, near Lønstrup, Denmark. Using a simple Mohr-Coulomb model for the soil, the computational model is able to reproduce the change in the slope geometry at the site.

Andersen, Søren; Andersen, Lars

2009-01-01

376

Slope-sensitive optical probe for freeform optics metrology  

Science.gov (United States)

Freeform and conformal optics represent the next generation of optical systems where their utilization leads to more compact, lighter, and higher performance systems for solar collectors, consumer optics, and defense applications. Optical coordinate measuring machines present one option for accurate metrology of freeform components but have two limitations: metrology system errors and optical probe errors. In this work, we address the latter of the two by demonstrating a compact optical probe capable of fiber delivery and fiber detection to remove potential heats sources away from measured optic. A bench top demonstrator has yielded a displacement resolution below +/-10 nm and has a noise floor of approximately +/-18 ?rad for surface slope in two orthogonal directions. In this Proceedings, we discuss our probe concept, operating principle, and preliminary measurements with a bench top proof-of-concept system. The goal of this work is to ultimately integrate this probe into OptiPro's UltraSurf, a 5-axis optical coordinate measuring machine for measuring freeform and conformal optics.

Echter, Michael A.; Keene, Andrew D.; Roll, Christopher D.; Ellis, Jonathan D.

2013-09-01

377

Gravity-induced stresses near topography of small slope  

Energy Technology Data Exchange (ETDEWEB)

Topographic modification of gravity-induced near-surface stresses results in significant departures from a lithostatic state. A perturbation scheme provides approximate analytic solutions for plane strain of an elastic half-space with an irregularly shaped free surface of small characteristic slope. The leading order effect of the topography is equivalent to that of a distributed normal load on a plane boundary, and the correction is due to a distributed shear traction on a plane boundary. Topography can exert a strong influence on the state of stress in the upper crust. An analytical solution to a relevant class of problems in elastostatics is presented: the gravity-induced stress field in a half-space with an irregularly shaped free surface. The analysis also is extended to consider the effect of topography on the stresses due to a far-field tectonic compression or tension. Motivation for this study stems from a broad range of problems in geology and geophysics. 20 references.

McTigue, D.F.; Mei, C.C.

1981-10-10

378

Petroleum geochemistry of Alaskan North Slope - an update  

Energy Technology Data Exchange (ETDEWEB)

Consideration of the basic requirements for oil occurrence (source, migration pathway, reservoir, trap, and seal) suggests that source rock adequacy may be a limiting factor in National Petroleum Reserve in Alaska (NPRA). Two geochemically distinct types of North Slope oil have been recognized: the Simpson-Umiat type (associated with a pebble-shale unit/Torok Formation source) and the Barrow-Prudhoe type (associated with a Shublik Formation/Kingak Shale source). Except for the oil from the Fish Creek 1 well and the reservoirs of Cretaceous age in the Prudhoe area, the Barrow-Prudhoe oil reservoirs are in Ellesmerian sequence rocks on the Barrow arch. The source-reservoir thermal-maturity patterns, the inferred timing of oil generation, and the structural configuration of the Ellesmerian rocks all suggest that the oil should have migrated to the Barrow area as well as to the Prudhoe area. The presence of subcommercial Barrow-Prudhoe-type oil in NPRA also suggests that deficiencies in the oil plumbing system do not explain the lack of oil accumulations along the Barrow arch. The large volumes of oil in the Prudhoe area, as compared to only oil shows in the Barrow area, are best explained by the greater amount and better quality or organic matter in the Shublik Formation and the Kingak Shale to the east of NPRA.

Magoon, L.B.; Claypool, G.E.

1985-04-01

379

Evolution of revegetated ski slopes in different environments  

Directory of Open Access Journals (Sweden)

Full Text Available Revegetation of ski slopes is a useful technique to limit soil erosion, reduce the visual impact of the tracks and lengthen the duration of snow cover. Restoration is often performed with commercial forage mixtures with the aim of creating a fast soil cover, then allowing the natural recolonization of artificial swards in the mid-long term. To investigate on the recolonization dynamics, data were collected from 21 different plots from the Alps and the Apennines (Valtellina, Plan de Corones, Sappada, Cimone. Knowledge of both the original mixtures used for restoration and the timespan since intervention (ranging from 1 to 21 years allowed to throw light on the naturalization process for the studied plots. Ground cover, floristic richness and relative presence of sown and native species were measured along linear transects established on the analyzed ski tracks. Results showed the effectiveness of plant restoration, in terms of soil coverage and (in some cases persistence of species of the original mixtures. Recovery of autochthonous species was strongly affected by site elevation and time elapsed since restoration. Moreover, the distance of ski lanes from forest edges seems to influence the dynamics of recolo­nisation process. Renaturalization was remarkably faster in the lower-altitude Apennine study plot. Application of a regression analysis revealed that elevation and timespan since restoration may be considered useful predictors of the level of naturalization of the restored canopies.

Argenti G

2011-12-01

380

A giant submarine slope failure on the insular slope north of Puerto Rico: A response of Arecibo basin strata to tectonic stress  

Energy Technology Data Exchange (ETDEWEB)

An amphitheater-shaped scarp, approximately 55 km across in water depths from about 3,000 m to 6,700 m was imaged on the northern insular slope of Puerto Rico (southern slope of the Puerto Rico Trench) using the GLORIA side-scan sonar system. This scarp represents the removal of more than 1,500 m{sup 3} of Tertiary Arecibo basin strata. The head of the scarp coincides with the location of a fault zone observed on nearby seismic-reflection profiles. Interpretation of the GLORIA imagery, and a review of available bathymetric, geophysical, and stratigraphic data and tectonic-framework models suggest that the scarp formed as a consequence of slope failure induced by tectonic oversteepening of the insular slope. The oversteepening may be a result of the most recent episode of convergence of the Caribbean and North American plates, which began approximately 4 million years ago. The Arecibo basin strata have been tilted approximately 4{degree} to the north and are apparently gravitationally unstable under the present seismic regime. The volume of material involved in this slope failure is comparable to the material displaced in tsunamogenic submarine landslides along the Peru Trench and Hawaiian Ridge. Therefore, if the slope failure north of Puerto Rico was catastrophic, it was large enough to have generated a tsunami that would have flooded the low ground of northern Puerto Rico.

Schwab, W.C.; Danforth, W.W.; Scanlon, K.M. (Geological Survey, Woods Hole, MA (USA))

1990-06-01

 
 
 
 
381

Oscillatory turbulent boundary-layer flows along thermally perturbed sloping surfaces (Invited)  

Science.gov (United States)

Buoyantly driven flows of stratified fluid along heated or cooled sloping surfaces conflate three charismatic aspects of geophysical fluid dynamics: buoyant forcing, stratification, and turbulence. Known as slope winds in meteorology, these air motions play an important role in the weather of vast areas of the Earth. It is common to distinguish between anabatic winds, which are driven by surface heating, and katabatic winds, which result from surface cooling. Many questions remain regarding particular physical aspects of these flows. Of specific interest for atmospheric modeling are parameters of slope flows as functions of the surface thermal forcing, ambient stratification, and slope angle. Physics of the slope flows will be briefly reviewed with an emphasis on their two specific features: (i) inherently oscillatory character and (ii) boundary-layer organization of particular slope-flow types (e.g., katabatic flows along shallow slopes). Long-period oscillations of velocity and buoyancy fields in natural and modeled/simulated slope flows have been reported in the literature rather often. The observed oscillation frequency was found to be approximately equal to the product of the environmental Brunt-Väisälä (buoyancy) frequency and the sine of the slope angle. However, evolution of the oscillations and the terminal state of the flow remain among topics of scientific discussion. In this study, the evolution of the oscillations was tracked over considerable time intervals (up to several hundreds of oscillation periods) using direct numerical simulation (DNS). The oscillations were analyzed in terms of velocity and buoyancy integrals as functions of time in conjunction with the time evolution of the surface stress. Analysis of the numerical data indicated that the slope flow system behaves as an imperfect ('dirty') underdamped oscillator: after an initial gradual decay of the oscillation amplitude, the flow evolves into a regime characterized by intermittent, although persistent, oscillatory eruptions whose magnitude remains relatively small but essentially non-zero. Structure of the governing slope-flow equations in the boundary-layer form - which is hypothetically a valid approximation for a katabatic flow along a shallow slope - has been examined. For this approximate flow case, the scaling laws have been deduced that involve only two non-dimensional parameters: the Prandtl number and a modified Reynolds number. The slope angle, which was an additional parameter in the original scaled slope-flow problem, appears in the approximate boundary-layer problem only as a factor in the modified Reynolds number. This feature could mean considerable savings of computer resources in parametric slope-flow studies. The validity of the proposed scaling hypothesis has been assessed using the DNS data.

Fedorovich, E.; Shapiro, A.

2013-12-01

382

Infants' Perception of Affordances of Slopes under High- and Low-Friction Conditions  

Science.gov (United States)

Three experiments investigated whether 14- and 15-month-old infants use information for both friction and slant for prospective control of locomotion down slopes. In Experiment 1, high- and low-friction conditions were interleaved on a range of shallow and steep slopes. In Experiment 2, friction conditions were blocked. In Experiment 3, the…

Adolph, Karen E.; Joh, Amy S.; Eppler, Marion A.

2010-01-01

383

Protection Roles of Gleditshia Caspica Dsf. on Slopes in Iran  

Directory of Open Access Journals (Sweden)

Full Text Available Slope instability due to landslides is particularly common in N Iran. It is possible to fight against these hazards thanks to the roots of scrubs, which provide an important contribution towards the stability of hillslopes. However, knowledge on the effectiveness of roots for slope stability needs improvement. Therefore, a study has been carried out on the effect of roots on slope stability, in particular for Gleditshia sp. The study area was located in Roudsar Township, in Gilan Province of N Iran. Some parts of this area cover with Gleditshia sp. forest tree. Soil samples with and without roots of the mentioned specie were taken, on an area of approximately 30 ha large, for testing in the laboratory. Soil shear tests were carried out on these samples and the Factor of Safety (FS was calculated. Results showed that the FS was increased in soils with roots present. The global slope FS was then determined using Bishop`s method. We calculated FS in order to protect slopes where the gradient exceeds 25%. In this case study, minimum FS which corresponds to Gleditshia sp. vegetation with greater than 60% crown cover, a soil internal friction angle of 15° and a slope angle of 18°. When soil internal friction angle equals 19° and slope angle is more than 23°, slope stability can not be increased by Gleditshia sp. species.

2007-01-01

384

Monitoring System for Slope Stability under Rainfall by using MEMS Acceleration Sensor IC tags  

International Nuclear Information System (INIS)

Real-time warning system for slope failure under rainfall is available to disaster prevention and mitigation. Monitoring of multi-point and wireless measurements is effective because it is difficult to conclude the most dangerous part in a slope. The purpose of this study is to propose a method of monitoring system with multi-point and wireless measurements for a slope stability using MEMS acceleration sensor IC tags. MEMS acceleration sensor IC tag is an acceleration sensor microminiaturized by a technology of Micro Electro Mechanical Systems on board IC tag. Especially, low cost of the sensor will yield to the realization of the system. In order to investigate the applicability of the proposed system, a large-scale model test of artificial slope subjected to rainfall has been performed. MEMS acceleration sensor IC tags has been located on the slope and ground acceleration caused by forced vibration has been measured until the model slope collapses. The experimental results show that the MEMS acceleration sensor IC tag is comfortably available under rainfall, the characteristics of ground accelerations varies with changing the condition of the slope subjected to rainfall, and the proposed method can be applied to a real-time monitoring system for slope failure under rainfall.

2013-06-17

385

Regional landslide-hazard evaluation using landslide slopes, Western Wasatch County, Utah  

Science.gov (United States)

Landsliding has historically been one of the most damaging geologic hazards in western Wasatch County, Utah. Accordingly, we mapped and analyzed landslides (slumps and debris slides) in the area to provide an empirical basis for regional landslide-hazard evaluation. The 336 landslides in the 250-sq-mi (650-km2) area involve 20 geologic units, including Mississippian- to Quaternary-aged rock and unconsolidated deposits. Landsliding in western Wasatch County is characterized by a strong correlation between geologic material and landslide-slope inclination. From a simple statistical analysis of overall slope inclinations of late Holocene landslides, we determined "critical" slope inclinations above which late Holocene landsliding has typically occurred and used these as the primary basis for defining relative landslide hazard. The critical slopes vary for individual geologic units and range from 15 to 50 percent (9??-27??). The critical slope values and landslide locations were used in conjunction with geologic and slope maps to construct qualitative landslide-susceptibility maps for use by county planners. The maps delineate areas of low, moderate, and high relative hazard and indicate where studies should be completed prior to development to evaluate site-specific slope-stability conditions. Critical slopes as determined in this study provide a consistent empirical reference that is useful for evaluating relative landslide hazard and guiding land-use-planning decisions in large, geologically complex areas.

Hylland, M. D.; Lowe, M.

1997-01-01

386

Laboratory Experiments on Steady State Seepage-Induced Landslides Using Slope Models and Sensors  

Directory of Open Access Journals (Sweden)

Full Text Available A thorough understanding of the failure initiation process is crucial in the development of physicallybased early warning system for landslides and slope failures. Laboratory-scale slope models were constructed and subjected to instability through simulated groundwater infiltration. This is done by progressively increasing the water level in the upslope tank and allowing water to infiltrate laterally towards the toe of the slope. Physical changes in the slope models were recorded by tilt sensors and video cameras. When the model slope was destabilized, the chronology of events occurred in the following sequence: (1 bulging at the toe, (2 seepage at the toe, (3 initial failure of soil mass, (4 piping, (5 retrogressive failure, (6 formation of tension cracks and (7 major failure of soil mass. Tension cracks, piping and eventual failure are manifestations of differential settlements due to variations in void ratio. Finite element analysis indicates that instability and subsequent failures in the model slope were induced primarily by high hydraulic gradients in the toe area. Seepage, initial deformation and subsequent failures were manifested in the toe area prior to failure, providing a maximum of 36 min lead time. Similar lead times are expected in slopes of the same material as shown in many case studies of dam failure. The potential of having a longer lead time is high for natural slopes made of materials with higher shear strength thus evacuation is possible. The tilt sensors were able to detect the initial changes before visual changes manifested, indicating the importance of instrumental monitoring.

Sandra G. Catane

2011-06-01

387

Toe clearance and velocity profiles of young and elderly during walking on sloped surfaces  

Science.gov (United States)

Background Most falls in older adults are reported during locomotion and tripping has been identified as a major cause of falls. Challenging environments (e.g., walking on slopes) are potential interventions for maintaining balance and gait skills. The aims of this study were: 1) to investigate whether or not distributions of two important gait variables [minimum toe clearance (MTC) and foot velocity at MTC (VelMTC)] and locomotor control strategies are altered during walking on sloped surfaces, and 2) if altered, are they maintained at two groups (young and elderly female groups). Methods MTC and VelMTC data during walking on a treadmill at sloped surfaces (+3°, 0° and -3°) were analysed for 9 young (Y) and 8 elderly (E) female subjects. Results MTC distributions were found to be positively skewed whereas VelMTC distributions were negatively skewed for both groups on all slopes. Median MTC values increased (Y = 33%, E = 7%) at negative slope but decreased (Y = 25%, E = 15%) while walking on the positive slope surface compared to their MTC values at the flat surface (0°). Analysis of VelMTC distributions also indicated significantly (p < 0.05) lower minimum and 25th percentile (Q1) values in the elderly at all slopes. Conclusion The young displayed a strong positive correlation between MTC median changes and IQR (interquartile range) changes due to walking on both slopes; however, such correlation was weak in the older adults suggesting differences in control strategies being employed to minimize the risk of tripping.

2010-01-01

388

[Community structure of soil fauna in Eucalyptus grandis plantations at different slope locations].  

Science.gov (United States)

To understand the effects of slope location on the community structure of soil fauna in Eucalyptus grandis plantation, an investigation was made on the soil fauna in 3 E. grandis plantations at different slope locations in the hilly area of Sichuan Province from January to October 2009. A total of 39,2762 individuals were observed, belonging to 146 groups, 7 phyla, 16 classes, and 31 orders. The community composition, trophic group, diversity, and seasonal dynamics of soil fauna in the plantations all varied with slope. The abundance of macro-fauna, xeric meso- and micro-fauna, saprophagous macro-fauna, and omnivorous xeric meso- and micro-fauna increased with the decrease of slope, indicating that soil fauna had sensitive responses to the soil environmental factors affected by slope. Significant differences in the diversity of soil saprophagous macro-fauna and hygrophilous meso- and micro-fauna were observed at different slope locations, suggesting that these two faunal groups could be used as the indicators of the habitat heterogeneity of E. grandis plantations at different slope. Overall, slope location had definite effects on the community structure and distribution of soil fauna in the E. grandis plantations, but the effects were not statistically significant. PMID:21265162

Zhao, Yu; Zhong, Yu; Zhang, Jian; Yang, Wan-qin

2010-09-01

389

The establishment of Atlantic Water transport as a topographically trapped slope current off Scotland  

Directory of Open Access Journals (Sweden)

Full Text Available Atlantic Water, with its origin in the western Atlantic, enters the Nordic Seas partly as a barotropic current following the continental slope. This water mass is carried across the Atlantic by the baroclinic North Atlantic Current (NAC. When the NAC meets the continental slope at the east side of the Atlantic, some of the transport is converted to barotropic transport over the slope before continuing northward. Here, we show that this baroclinic to barotropic conversion is in agreement with geostrophic theory. Historical observations show that the transport of the slope current increases significantly from the Rockall Channel (RC to the Faroe–Shetland Channel (FSC. Geostrophy predicts that with a northward decreasing buoyancy, baroclinic currents from the west will be transferred into northward topographically steered barotropic flow. We use hydrographic data from two sections crossing the continental slope, one located in the RC and another in the FSC, to estimate baroclinic and barotropic transport changes over the slope, within the framework of geostrophic dynamics. Our results indicate that ~1 Sv of the cross-slope baroclinic flow is mainly converted to northward barotropic transport above the 200–500m isobaths, which is consistent with observed transport changes between the RC and the FSC. Similar processes are also likely to occur further south, along the eastern Atlantic margin. This shows that AW within the slope current in the FSC is derived from both the eastern and the western Atlantic, in agreement with earlier studies of AW inflow to the Nordic Seas.

Qin Zhou

2013-05-01

390

Riprap stability on the inner slopes of medium-height breakwaters:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Medium height breakwaters are subjected to a considerable amount of overtopping. This implies the armour on the inner slope has to stable against overtopping waves. Existing equations do lack some basic understanding of the process of starting up movement of rock on the inner slopes.

2003-01-01

391

Developing Restoration Planting Mixes for Active Ski Slopes: A Multi-Site Reference Community Approach  

Science.gov (United States)

Downhill ski areas occupy large expanses of mountainous lands where restoration of ecosystem function is of increasing importance and interest. Establishing diverse native plant communities on ski runs should enhance sediment and water retention, wildlife habitat, biodiversity and aesthetics. Because ski slopes are managed for recreation, ski slope revegetation mixes must consist of low-stature or herbaceous plants that can tolerate typical environmental conditions on ski slopes (high elevation, disturbed soils, open, steep slopes). The most appropriate reference communities for selecting ski slope revegetation species are thus successional, or seral plant communities in similar environments (i.e., other ski slopes). Using results from a broad-scale reference community analysis, I evaluated plant communities naturally occurring on ski slopes from 21 active and abandoned ski areas throughout the northern Sierra Nevada to identify native plant species suitable for use in ski slope restoration. I constructed a baseline planting palette of regionally appropriate plant species (for restoration of either newly created or already existing ski runs) that is functionally diverse and is likely to succeed across a broad range of environments. I also identify a more comprehensive list of species for more specialized planting mixes based on site-specific goals and particular environmental settings. Establishing seral plant communities may be an appropriate restoration goal for many other types of managed lands, including roadsides, firebreaks and utility rights-of-way. This study describes an ecological (and potentially cost-effective) approach to developing restoration planting palettes for such managed lands.

Burt, Jennifer Williamson

2012-03-01

392

Slope stability improvement using low intensity field electrosmosis  

Science.gov (United States)

The electrosmosis technique has been introduced in the past for slope stabilization. However, its application to real cases has been scarce due to several drawbacks mostly related to the high intensity electric field needed (1.0 V/cm or higher): the rapid degradation of the electrodes, the high system management cost, the heating and cracking of the soil and the reduction of its colloidal fraction. Thanks to the introduction of new materials, the technique is currently applied to decrease the consolidation time of saturated clay soils (forcing the elimination of water), consequently improving its mechanical strength. In clay soils, the volume variation is influenced by the presence of smectites. The clay compressibility decreases with the increasing of electrolytes concentration. Soil containing smectites that have interacted with calcium showed a reduction or the absence of swelling during hydration with distilled water and a positive increase of their shear strength. The different values of pH between the anode (acid) and the cathode (basic), induced by the electrosmosis create the conditions for the precipitation of CaCO3 near the cathode. The injection of solutions containing calcium in soils and their diffusion induced by the electrosmosis, lead to calcium precipitation and consequential increase of the shear strength. The material technological advances and the laboratory experiences described in this paper, demonstrate that the use low electric field (0.1 V/cm or lower) intensity electrosmosis (LEFE in acronym) can be effective for soil dewatering and shear strength increase while reducing its adverse effect. The LEFE can be used to: reduce the potential for swelling of active clay minerals through the introduction of ions and the precipitation of hardening substances; induce the "dewatering" in cohesive soils. Several Lab activities were carried out, using custom made electrosmosis equipment. These activities can be divided in two phases: Phase 1: Carbonates were mixed to a natural soil obtaining three groups of soil samples at different carbonates level; the geotechnical characterization of each group was carried out; Phase 2: LEFE was applied to induce the precipitation of CaCO3, the reduction of the swelling potential of clay minerals and the increment of the soil shear strength. The outcomes of Phase 1 indicated that: the values of specific gravity of the grains, plasticity index (PI) and Value of Blue (VB) decrease with the increase carbonate content; the shear strength increases with the carbonates content. From the second laboratory phase, we observed: an almost constant pH values within the sample; an increment of the carbonate content after LEFE treatment regardless of its duration; this increment is particularly significant after 60 days of treatment; a reduction of the swelling potential of soil; that the water content at the end of each treatment, regardless of its duration and intensity of the electric field, shows similar values; that the values of the soil shear strength (after 60 days of LEFE treatment) are always greater than those of the natural soil (average +7%). During the LEFE treatment, the pore fluid used is water taken from the local groundwater, with pH = 7.3 and hardness of 34.6 ° F. The CaCO3 content in treated samples increases with the duration of treatment. The application of LEFE appears to be effective in increasing the carbonate content and improve mechanical strenght of the soil; further development of the research will apply the LEFE to an ideal slope model and to a real case.

Armillotta, Pasquale

2014-05-01

393

Experimental Observations On Turbidity Currents Flowing Over Low Bed Slopes  

Science.gov (United States)

Turbidity currents are gravity-driven, sediment-laden turbulent flows moving on a sloping bottom, which take place in oceans and lakes. Due to the difficulties to predict and observe this kind of phenomena in nature, in the recent past many experimental apparatus were set up to increase the comprehension of the currents. We developed an experimental apparatus able to reproduce such kind of currents in our Marchi Environmental Laboratory. The experiments were performed in an horizontal flume U shaped in plan, 30 m long, characterized by two straight tracks approximately 12 m in length, and a bend with a constant radius of curvature equal to 2.5 m. The flume, made in plexiglass, has a rectangular cross section 0.6 m wide and 0.5 m deep. The particular shape of the channel let us study the spatial development of turbidity (or saline) currents in the straight reach and the adjustment of the flow in the channel bend. We have created a concrete fixed bed with an uniform bottom slope of 0.005 developing both along the first straight and the constant curvature bend and continuing 3 meters after the bend exit. The first set of experimental observations were performed employing an 'hybrid' turbidity current, in that the density excess was created by adding both salt and fine sediments (d50=4 micron) to clear water. Each run, characterized by the same initial and boundary conditions (fractional density excess, discharge of the mixture, inlet and outlet conditions) and by the same geometry, was repeated many times in order to measure vertical velocity and density profiles in different cross sections along the straight and bend reaches. Both longitudinal and lateral velocity measurements were performed, as well as density profiles. The velocity profiles were acquired using an ultrasound Doppler velocimeter profiler. In this way we recorded the longitudinal velocity in the channel axis with a spatial resolution of 1 m along the flume and, coupling the data of two probes aligned in the cross section with different angles, we were able to obtain the ver