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1

Thermal regime of an alpine talus slope  

Science.gov (United States)

In mountain areas, the permafrost is largely discontinuous. The modelling of its extension requires the identification and the comprehension of the different factors which control the ground thermal regime. Located in the west flank of the Mont Gelé (Valais Alps, Switzerland, 3023 m a.s.l.), between 2600 and 2800 m a.s.l. (MAAT about -1°C), Les Attelas talus slope has been investigated since 2001. According to direct observations (borehole drilling) and to a large set of geoelectrical and thermal data (ground surface and borehole measurements), permafrost is present in the lower half of the slope. This configuration is common in mountain talus slopes (Lambiel and Pieracci, 2008). Mean annual ground surface temperature (MAGST) recorded downslope by two loggers between 2001 and 2007 is about +0.3°C. Temperatures increase upslope, where MAGST can reach +4°C in some places. Summer ground surface temperatures are rather homogeneous all over the landform. The lower part of the slope is not especially colder than the upper part. Places located downslope are even warmer than places located some tens of meters higher. The warmest temperatures are generally measured where fine-grained sediment is present, but there is no clear relationship between the coarseness of the blocs and the summer temperatures. In winter, the ground surface temperatures are clearly correlated with the altitude: a strong cooling occurs downslope (equilibrium temperatures are often around -5°C), whereas temperatures remain close to 0°C upslope. The data shows that the granulometry does not have a strong influence on the winter ground temperatures. The good correspondence between the highest electrical resistivities and the coldest winter ground surface temperatures indicates that the cooling occurring in the lower part of the slope in winter is probably the cause of the presence of permafrost in this sector. The repeated passage of skiers in this area may increase the thermal conductivity of the snow, which may slightly cool down the ground. However, it is probably not sufficient to provoke such a thermal contrast between up- and downslope. The chimney effect is known to be a key controlling factor for the ground overcooling in low elevation talus slopes (Delaloye et al. 2003). In Les Attelas, data in the upper part of the slope shows that winter cold spells provoke regularly a warming of the ground, while the warm periods of the winter are often accompanied by a ground cooling. In the lower part of the slope however, there is no evidence of ground overcooling by aspiration of cold outside air through the snow cover. Thus, a slight chimney effect seems to work, even if its strength is limited. This is probably due to the presence of ice-saturated sediments below 3.5 - 5 m deep (borehole data), which confine the mechanism to the active layer. However, the mechanism is probably sufficiently effective to cause a lateral cooling (air advection) by the movement of warm air upslope. This would explain the cold temperatures measured downslope. REFERENCES Delaloye R., Reynard E., Lambiel C., Marescot, L., Monnet R. 2003. Thermal anomaly in a cold scree slope (Creux du Van, Switzerland). Proceed. 8th Int. Conf. Permafrost, Zurich 2003, 1, 175-180. Lambiel C., Pieracci K. 2008. Permafrost distribution in talus slopes located within the alpine periglacial belt, Swiss Alps. Permafrost and Periglacial Processes 19: 293-304.

Lambiel, C.; Scapozza, C.

2009-04-01

2

Talus slope development: an integrated concept based on the Eastern Alps.  

Science.gov (United States)

Talus slopes are deposystems that accumulate in onlap onto the area of sediment provenance, that is, rock cliffs. 'Talus slope - rock cliff ensembles' are subject to strong internal feedback due to the direct interplay of slope accumulation with cliff degradation. Our field observations in numerous Quaternary talus-slope successions indicate an overall predictable relation between talus slope maturity, depositional geometry, and sedimentary facies: After exposure of rock cliffs by deglaciation or rocksliding, a low-dipping immature talus (dominated by debris flows and/or by rockfalls) or a rock glacier initially accumulates. Upon progressive aggradation and steepening of the proximal slope segment, prevalent processes of deposition change to grain flows and 'sorted rockfalls' in the steep-dipping (30-35°) proximal slope segment, while deposits of debris flows, ephemeral fluid flows, and rare large rockfalls prevail on the distal, lower-dipping slope segment. In successions of mature talus slopes, the proximal slope package overlies the lower-dipping, distal slope deposits along a narrow 'downlap interval'. The downlap interval is characterized by a marked upslope steepening of bedding surfaces over a short vertical and lateral distance. Immediately after cliff exposure by deglaciation or rocksliding, talus can aggrade at rates of up to a few tens of meters per 1000 years; initially high accumulation rates, however, decrease rapidly with buildup of slope and consequent burial of the rock cliff. On present carbonate-lithic talus slopes of the Eastern Alps the prevalent processes of sediment transport, final deposition, and deposit overprint in many cases change over lateral distances of a few tens to a few hundreds of meters; this gives rise to different types of talus slopes. Whereas glacial-interglacial cycles determine presence/absence of talus, as well as the altitude range of effective talus formation, minor climatic changes thus are hardly to read clearly from fossil talus successions. The highly non-steady character of accumulation, intercalated with phases of inactivity or erosion, further devaluates talus successions as faithful recorders of palaeoenvironmental change. In mountain ranges subject to glacial-interglacial cycles, most talus-slope successions correspond to the transgressive and highstand systems tract, respectively, of marine glacio-eustatic depositional sequences. Talus slope successions represent the altitudinally highest 'tip' of depositional sequences driven by glacial-interglacial cycles, and can comprise unconformity-bounded synthems.

Sanders, D.; Ostermann, M.

2009-04-01

3

Towards the automated geomorphometric extraction of talus slopes in Martian landscapes  

Science.gov (United States)

Terrestrial talus slopes are a common feature of mountainous environments. Their geomorphic form is determined by their being constituted of scree, or similar loose and often poorly sorted material. Martian talus slopes are governed by the different nature of the Martian environment, namely: weaker gravity, the wide availability of loose material, the lack of fluvial erosion and the typicality of large escarpments; all these factors make talus slopes a more striking areomorphic feature on Mars than on Earth. This paper concerns the development of a numerical geomorphometric analysis, parameterization and detection of the talus slopes method. We design inventive variables, a multidirectional visibility index (MVI) and a relief above (RA) and propose two techniques of talus slope extraction: ISOcluster and progressive Boolean overlay. Our Martian digital terrain model (DTM) was derived from the ESA Mars Express HRSC imagery, with a resolution of 50 m. The method was tested in the study areas of Nanedi Valles and West Candor Chasma. The major challenge concerned the quality of the DTM. The selection of robust variables was therefore crucial. Our final model is to a certain degree DTM-error tolerant. The results show that the method is selective concerning those slopes that can be considered to constitute a talus slopes area, according to the visual interpretation of HRSC images. Based on an analysis of the DTM, it is possible to infer various geological properties and geophysical processes of the Martian and terrestrial environments; this has a range of applications, such as natural hazard risk management.

Podobnikar, Tomaž; Székely, Balázs

2015-01-01

4

Debris flow-dominated and rockfall-dominated talus slopes: Genetic models derived from GPR measurements  

Science.gov (United States)

Stratified talus deposits are reported from many different mountain environments. Numerous possible explanations are discussed in the literature; however, the sediment stores are rarely accessible as exposures are sparse. We applied ground-penetrating radar (25, 50 and 100 MHz antennae) to gain insight into the internal sediment structures of 23 alpine scree slopes; ten examples are presented in this paper. The study areas are spread over the Eastern European Alps at altitudes ranging from 1500 to 2900 m. The bedrock type is primarily limestone and dolostone; one area is composed of gneiss and mica-schist. GPR turned out to be highly suitable for investigating sediment structures of dry talus debris. The results showed that almost all of the deposits investigated are characterized by pronounced stratification. Several different types of layering were identified. Discordant layers which are restricted to confined parts of the talus are probably related to sediment redistribution processes like surficial debris flows or dry grain flows. These features frequently occur at the uppermost part of the slope caused by overland flow from the adjacent rock face, but may also develop in the downhill part of a talus. One talus in the Reintal area showed surface-parallel, persistent layers of different grain sizes which cannot be explained by any known models. We suggest a novel model of talus development which is driven by climatic fluctuations. In periods of enhanced freeze-thaw activity like the Little Ice Age, the delivery of coarse debris prevails. In warmer climate with a higher frequency of rainstorms, the depletion of finer-grained intermediate stores in less inclined rockwall positions leads to delivery of clasts smaller than 2 cm. The type of layering found within a talus is determined by rockwall parameters like height, steepness, topography and dissection of the rock face. The "storage depletion" model applies to high rockwalls with a considerable volume of intermediate storage.

Sass, O.; Krautblatter, M.

2007-04-01

5

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

6

Geodynamics, plants colonization and phytodiversity on talus slopes in the Grande Chartreuse massif (Northern French Lower Alps). Geo-ecological characteristics and sensibility relating to environmental changes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Due to their rich ecosystems and great plant diversity, the talus slopes of the Grande Chartreuse massif have been designated by the European Directive on Habitats, Fauna and Flora, as sites of community interest. The plant diversity on these talus slopes seems to be a function of the mosaic landscape structure, whose complex dynamics are determined by the interaction of topo-climatic, edaphic, geomorphologic, geodynamic and biological factors, that act at several spatio-temporal scales. The ...

Arques, Sylvie

2005-01-01

7

Post-last glacial alluvial fan and talus slope associations (Northern Calcareous Alps, Austria): A proxy for Late Pleistocene to Holocene climate change  

Science.gov (United States)

Near Innsbruck city (Austria, Eastern Alps), following the Last Glacial Maximum (LGM), an alluvial fan-to-talus slope succession was supplied from a carbonate-rock cliff more than 1000 m in height. 234U/ 230Th ages of 9.5 to 9.37 isotope kyrs of diagenetic cements in the alluvial-fan succession suggest that the fan/talus deposit accumulated mainly during late-glacial to, perhaps, early Holocene times. The deepest-exposed interval of the fan succession contains cracked lithoclasts probably fractured by overburden from late-glacial ice; this interval is topped by an intra-sequence unconformity. Following final glacial retreat, and rapid aggradation of the alluvial fan and talus slope, the geomorphic regime changed to erosion, as recorded by fanhead trenching and cutting of fluvial terraces, abandonment and vegetating of scree slopes, and excavation of 'talus flatirons'. The changeover from the accumulation of fan and talus to abandonment and dissection probably took place during the terminal late-glacial interval to perhaps the early Holocene. This erosional regime persists until present. A record of rapid late-glacial to early Holocene accumulation of an alluvial fan/talus deposit followed by: (i) abandonment and vegetation growth, combined with (ii) cutting of intra-sequence unconformities of limited lateral extent, is typical of Alpine mountain-flank deposystems situated at comparatively low altitudes. This record consists of (a) an autocyclic component, that is, progressive lowering of sediment input due to onlap and burial of freshly-deglaciated mountain flanks supplying alluvial fans and talus slopes, and (b) an allocyclic component, that is, deglacial climatic warming and upward rise of an altitudinal range with a maximum number of freeze-thaw cycles ('talus window'), also leading to progressive vegetation-induced hillslope stabilization and lowering of scree production.

Sanders, Diethard; Ostermann, Marc

2011-08-01

8

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

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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...

Delaloye, Reynald; Lambiel, Christophe

2005-01-01

9

Osteoid osteoma of the talus  

International Nuclear Information System (INIS)

The osteoid osteoma of the talus accounts for 5% of these tumors, and it usually has a confusing symptomatology as well as a difficult radiological diagnosis. We report a case localized in the neck of the talus in an 18-year-old man who had been complaining of pain in this zone for four years, and MRI study showed the lesion. Medullar edema and cortical irregularity in the neck suggested the diagnosis, which was proved by pathology

10

Osteochondral Allograft of the Talus  

Science.gov (United States)

Osteochondral lesions of the talus are being recognized as an increasingly common injury. They are most commonly located postero-medially or antero-laterally, while centrally located lesions are uncommon. Large osteochondral lesions have significant biomechanical consequences and often require resurfacing with osteochondral autograft transfer, mosaicplasty, autologous chondrocyte implantation (or similar methods) or osteochondral allograft transplantation. Allograft procedures have become popular due to inherent advantages over other resurfacing techniques. Cartilage viability is one of the most important factors for successful clinical outcomes after transplantation of osteochondral allografts and is related to storage length and intra-operative factors. While there is abundant literature about osteochondral allograft transplantation in the knee, there are few papers about this procedure in the talus. Failure of non-operative management, initial debridement, curettage or microfractures are an indication for resurfacing. Patients should have a functional ankle motion, closed growth plates, absence of cartilage lesions on the tibial side. This paper reviews the published literature about osteochondral allograft transplantation of the talus focusing on indications, pre-operative planning, surgical approaches, postoperative management, results and complications of this procedure. PMID:25328456

Bisicchia, Salvatore; Rosso, Federica; Amendola, Annunziato

2014-01-01

11

PHYTOGEOGRAPHICAL INDICATORS OF TALUS DYNAMICS ON ACTIVE SCREES IN THE HIGH RANGES OF THE EASTERN PYRENEES  

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This work aims to understand the dynamics of slope debris systems located above the treeline in the eastern Pyrenees. The degree of activity and mode of evolution of these talus slopes is investigated by analysing the relationships that exist between lithophile plant species and slope morphodynamics. The elevated ranges of the eastern Pyrenees are well suited to studying these processes due to a large population of scree deposits occurring in settings favourable to clast production, to the pr...

Huc, Ste?phanie

2010-01-01

12

Completely extruded talus without soft tissue attachments  

Directory of Open Access Journals (Sweden)

Full Text Available A completely extruded talus without any remaining soft tissue attachments is extremely rare. The present report describes treatment of a 45-year-old man who sustained a completely extruded talus injury following a rockclimbing fall. Upon admission, the extruded talus was deep-frozen in our bone bank. The open ankle joint underwent massive wound debridement and irrigation for 3 days. Four days later we performed a primary subtalar fusion between the extruded talus and the calcaneus, anticipating revascularization from the calcaneus. However, aseptic loosening and osteolysis developed around the screw and talus. At 12 months post-trauma we performed a tibiocalcaneal ankle fusion with a femoral head allograft to fill the talar defect. Follow-up at 24 months post-trauma showed the patient had midfoot motion, tibio-talar-calcaneal fusion, and was able partake in 4-hour physical activity twice per week.

Jin-Soo Suh

2011-03-01

13

Lopsakalt rahvuslik mood Pulga talus / Tanel Veenre  

Index Scriptorium Estoniae

Eesti Moekunstnike Ühenduse näitus "Lillemotiiv moevormil" Eesti Vabaõhumuuseumi Pulga talus. Osalevad Anne Metsis, Anneliis Vabul, Diana Denissova, Monika Kisand, Juta Piirlaid, Anu Hint ja moekunsti õppejõud Yumiko Okazaki Jaapanist. Eksponeeritud rõivamudelid on kaunistatud rahvuslikest tikanditest inspireeritud stiliseeritud kujunditega

Veenre, Tanel, 1977-

2009-01-01

14

A new approach to the treatment of congenital vertical talus  

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Congenital vertical talus is an uncommon foot deformity that is present at birth and results in a rigid flatfoot deformity. Left untreated the deformity can result in pain and disability. Though the exact etiology of vertical talus is unknown, an increasing number of cases have been shown to have a genetic cause. Approximately 50% of all cases of vertical talus are associated with other neuromuscular abnormalities or known genetic syndromes. The remaining 50% of cases were once thought to be ...

Alaee, Farhang; Boehm, Stephanie; Dobbs, Matthew B.

2007-01-01

15

Analysis of Cliff Retreat and Rockfall Talus Deposition Patterns through Geomorphologic Analysis, Physical Modeling and Numerical Simulation  

Science.gov (United States)

During storms or earthquakes, Rockfall is a frequent mishap in mountain areas. Reviewing the histories of rockfall disasters in Taiwan, as the cluster of rockfall consists of simultaneous movements, it might cause serious disasters, which had occurred in Central Cross-lsland highway, Nanyali, Maijin road of Jilong City, Taidong Zhiben river, and the landslide-blocked lake of Longquan river. Such disasters have threatened the safety of life and need to be concerned. Whereas, this research study the relationship of talus deposits development induced by various cliff retreat types in Hungtsaiping rockfall area. In the present paper, we analyzed the geomorphologic changes of cliffs and talus deposits based on the findings from the topographic maps and interpreting aerial photos. The physical modeling was then carried out which was helpful to understand the relationship of cliff retreat and talus deposition patterns. The results of physical modeling were compared with those produced by numerical simulation (Application of discrete element method by PFC3D 3.0 program) so that the correctness of the numerical simulation could be justified. Subsequently, calibrated numerical methods adopted in the small-scale model were used to simulate the full-scale model. The simulation results should be as close to reality as much as possible. Finally, the shape function of talus deposition topographic patterns and the cluster of rockfall influence area for various cliff retreat types. Furthermore, the shape function reflects the deposits characteristic of main factors (the factor includes the slope angle of movement area, the fall height, rockfall amount, the joints spacing, the mean roughness height of deposition area, cliff retreat type) through the full-scale model simulation and physical modeling tests. The shape function are helpful for rockfall hazard zonation and developing reasonable and scientifically sound guidelines while giving land use assessment and protection engineering sited in rockfall area. Keywords: rockfall disaster, cliff retreat, talus deposits, geomorphologic analysis, physical modeling, numerical simulation, shape function

Lin, Ming-Lang; Lo, Chia-Ming; Lien, Tsun-Kai

2010-05-01

16

A new approach to the treatment of congenital vertical talus.  

Science.gov (United States)

Congenital vertical talus is an uncommon foot deformity that is present at birth and results in a rigid flatfoot deformity. Left untreated the deformity can result in pain and disability. Though the exact etiology of vertical talus is unknown, an increasing number of cases have been shown to have a genetic cause. Approximately 50% of all cases of vertical talus are associated with other neuromuscular abnormalities or known genetic syndromes. The remaining 50% of cases were once thought to be idiopathic in nature. However, there is increasing evidence that many of these cases are related to single gene defects. Most patients with vertical talus have been treated with major reconstructive surgeries that are fraught with complications such as wound necrosis, talar necrosis, undercorrection of the deformity, stiffness of the ankle and subtalar joint, and the eventual need for multiple operative procedures. Recently, a new approach to vertical talus that consists of serial casting and minimal surgery has resulted in excellent correction in the short-term. Longer follow-up will be necessary to ensure maintenance of correction with this new technique. A less invasive approach to the correction of vertical talus may provide more favorable long-term outcomes than more extensive surgery as has been shown to be true for clubfoot outcomes. PMID:19308490

Alaee, Farhang; Boehm, Stephanie; Dobbs, Matthew B

2007-09-01

17

Giant cell tumor of talus: a case report.  

Science.gov (United States)

Giant cell tumor of talus is a rare entity. In contrast to GCT of long bones, most cases occur in a younger age group and tend to be multicentric. The authors report a case of GCT in a 19 year old boy which had led to extensive destruction of the talus. In view of the extensive involvement, total talectomy along with tibio - calcaneal arthrodesis was performed. At 6 months of followup, the patient had a painless and well arthrodesed ankle. There was no evidence of recurrence at 18 months of followup. PMID:19159463

Sharma, Siddhartha; Wani, Iftikhar H; Gupta, Nital; Mahajan, Nirdosh; Salaria, Abdul Q

2009-01-01

18

Giant cell tumor of talus: a case report  

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Giant cell tumor of talus is a rare entity. In contrast to GCT of long bones, most cases occur in a younger age group and tend to be multicentric. The authors report a case of GCT in a 19 year old boy which had led to extensive destruction of the talus. In view of the extensive involvement, total talectomy along with tibio – calcaneal arthrodesis was performed. At 6 months of followup, the patient had a painless and well arthrodesed ankle. There was no evidence of recurrence at 18 months of...

Sharma, Siddhartha; Wani, Iftikhar H.; Gupta, Nital; Mahajan, Nirdosh; Salaria, Abdul Q.

2009-01-01

19

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

20

Three-dimensional geometric analysis of the talus for designing talar prosthetics.  

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Proper understanding of the complex geometric shape of the talus bone is important for the design of generic talar body prosthetics and restoration of the proper ankle joint function after surgery. To date, all talus implants have been patient-specific with the limitation that complex computer modeling is required to produce a mirrored image from the unaffected opposite side followed by machining a patient-specific prosthesis. To develop an "off-the-shelf" non-custom talar prosthesis, it is important to perform a thorough investigation of the geometric shape of the talus bone. This article addresses the applicability of a scaling approach for investigating the geometric shape and similarity of talus bones. This study used computed tomography scan images of the ankle joints of 27 different subjects to perform the analysis. Results of the deviation analyses showed that the deviation in the articulating surfaces of the talus bones was not excessive in terms of talus size. These results suggest that a proposed range of five implant sizes is possible. Finally, it is concluded that the talus bones of the ankle joints are geometrically similar, and a proposed range of five implant sizes will fit a wide range of subjects. This information may help to develop generic talus implants that might be applicable to patients with a severe talus injury. PMID:24622981

Islam, Kamrul; Dobbe, Ashlee; Duke, Kajsa; El-Rich, Marwan; Dhillon, Sukhvinder; Adeeb, Samer; Jomha, Nadr M

2014-04-01

 
 
 
 
21

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

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  

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.

2012-03-01

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Bedrock detection and talus thickness assessment in the European Alps using geophysical methods  

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Three different geophysical techniques (ground-penetrating radar (GPR), 2D-resistivity, seismic refraction) were applied to measure sediment thickness of alpine talus slopes. The eight study areas covered a range of different rock types, aspects and elevations and are mainly situated in the north-eastern part of the European Alps. A total of more than 30 scree slopes were investigated. The emphasis was on the application of GPR. The other two methods were used additionally in five areas to verify the GPR results and to check the concurrence of the results. With all the techniques applied, certain difficulties of bedrock detection arose. GPR surveys using several frequencies seem to be the most powerful tool for detecting the bedrock surface and internal structures in these high-alpine environments. However, there frequently is no radar wave reflection at the debris-bedrock interface due to the rather similar dielectrical properties. This problem was overcome by using the characteristic reflection patterns of the subsurface units for delimitating debris from glacigenic sediments and bedrock. Typical radar facies are presented. The other two methods applied were impeded by the broad overlap between resistivity and seismic velocity values, respectively, of the subsurface layers. The widespread presence of compacted and/or glacigenic debris layers between surficial scree and bedrock rendered the interpretation difficult. The three methods coincide well in straightforward settings (e.g. debris superimposing bedrock). Additional sediment units like till, wet or compacted debris lead to considerable ambiguities and deviations between the results. Thus, the combined application of two or three techniques is strongly advisable to verify and improve the interpretation. The calculated Holocene rockwall retreat rates lay between 200 and 850 mm/ka which is well within the framework of previous measurements. The weathering rates at north faces seem to be roughly two times higher than at south faces in the areas of investigation.

Sass, Oliver

2007-07-01

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Operative treatment of osteochondral lesions of the talus.  

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? Osteochondral lesions of the talus are common injuries in recreational and professional athletes, with up to 50% of acute ankle sprains and fractures developing some form of chondral injury. Surgical treatment paradigms aim to restore the articular surface with a repair tissue similar to native cartilage and to provide long-term symptomatic relief.? Arthroscopic bone-marrow stimulation techniques, such as microfracture and drilling, perforate the subchondral plate with multiple openings to recruit mesenchymal stem cells from the underlying bone marrow to stimulate the differentiation of fibrocartilaginous repair tissue in the defect site. The ability of fibrocartilage to withstand mechanical loading and protect the subchondral bone over time is a concern.? Autologous osteochondral transplantation techniques replace the defect with a tubular unit of viable hyaline cartilage and bone from a donor site in the ipsilateral knee. In rare cases, a graft can also be harvested from the ipsilateral talus or contralateral knee. The limitations of donor site morbidity and the potential need for an osteotomy about the ankle should be considered. Some anterior or far posterior talar lesions can be accessed without arthrotomy or with a plafondplasty.? Osteochondral allograft transplantation allows an osteochondral lesion with a large surface area to be replaced with a single unit of viable articular cartilage and subchondral bone from a donor that is matched to size, shape, and surface curvature. The best available evidence suggests that this procedure should be limited to large-volume cystic lesions or salvage procedures.? Autologous chondrocyte implantation techniques require a two-stage procedure, the first for chondrocyte harvest and the second for implantation in a periosteum-covered or matrix-induced form after in vivo culture expansion. Theoretically, the transplantation of chondrocyte-like cells into the defect will result in hyaline-like repair tissue. PMID:23780543

Murawski, Christopher D; Kennedy, John G

2013-06-01

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Stress analysis during slope failure from DEM simulations  

Science.gov (United States)

We used Discrete Element Method (DEM) simulations to study the initiation and evolution of landsliding, with a focus on the development and propagation of the sliding plane, and on the effects of material strength on the behavior of the slope material during landsliding. Our simulated slopes were constructed of homogeneous materials, settled under gravity, bonded, and excavated to produce 70 deg slopes of 1050 m in height. Nine simulations were carried out, each using a different value of cohesions, ranging from 0.7 to 4.2 MPa (quantified through DEM direct shear simulations on representative materials). In each of our simulations, failure initiated at the foot of the slope, accompanied by disintegration of the slope material. Failure then propagated upward to the slope crest with further material disintegration. A discrete detachment surface formed below the disintegrated material. Downslope movement of the failed material (i.e. landsliding) occurred only after the failure plane intersected the upper slope face. By the end of landsliding, the disintegrated slope material formed a talus like deposit at the foot of the slope. The value of initial material cohesion influenced the nature of the landslide deposit and its dimension. Higher material strengths produced smaller landslides, as well as the occurrence of discrete landslide blocks, which originated from the shallow slopes, and became entrained within the finer talus. Stress analysis of the slope failure process clarifies how failure initiates and landsliding evolves, and further constrains the limiting failure criteria that define each simulated material. The local proximity to failure throughout the slope can be tracked during the simulation, revealing that high failure potential (high shear stress relative to mean stress) exists at the toe of the slope immediately following excavation. As material disintegrates near the toe of the slope, high tensile stresses develop in the overlying mass, causing the break-up of the shallower slope materials. The detachment surface defines the boundary between the mobile material undergoing disintegration and the coherent material below. With increased cohesion within the slope, less material reaches this failure condition, and the detachment surface shallows, causing a decrease in the in-slope extent of the landslide, the volume of the final deposit and type of failure (slump vs. rock-slide). These numerical simulations provide important insights into the stress evolution within a failing slope, and an understanding of how these control the final type, geometry and size of landlides.

Katz, O.; Morgan, J. K.

2012-04-01

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Sediment storage and transfer on a periglacial mountain slope (Corvatsch, Switzerland)  

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High mountain geomorphology is mostly characterized by high elevation, steep gradients, rocky terrain, the presence of snow and ice and the related processes occurring in a high energy environment. Large sources of sediment and sediment storages often exist within high mountain systems and are controlled by the processes occurring within this setting. The purpose of this study is to describe sediment paths on a periglacial mountain slope and quantify geomorphic work within one example year in order to analyze and compare sediment budgets in high mountain geosystems. This energy-related approach helps to characterize a periglacial slope on account of the effectiveness of its geomorphological processes and might help to understand the complex dynamic behavior of its constituent subsystems. A periglacial mountain slope is investigated in Eastern Switzerland (Corvatsch). The environment is characterized by a typical coarse debris cascade: rock wall ? rock fall ? talus slope ? permafrost creep ? rockglacier. Rockglaciers are considered to be sediment traps of the coarse debris system, reflecting the erosion history of the corresponding catchment. Headwall recession and creep processes of the talus slopes and rockglaciers are quantified by a multi-method-approach combining remote sensing and terrestrial methods. Multitemporal DEMs of the last two decades enabled the quantification of sediment transfer of the slow moving landforms (frozen talus slopes and rockglaciers). Sediment input from the rock wall is quantified by repeated laser scanning over the last 4 years. With the introduced cascading approach it is possible to assess dynamics within the coarse debris system. The mountain slope is divided into three subsystems (headwall, talus cone and rockglacier) and their dynamics are analyzed individually but also in relation to the entire mountain slope on a yearly base. A backweathering rate of 2 mm can be derived for the headwall and an energy transfer of 29.8 GJ from the headwall to the slope, 4 GJ from the talus slope to rockglacier where 1.44 GJ of geomorphic work are released by the downwards creep of the landform. This study is the first to include an analysis of the geomorphic work generated on the basis of vertically differentiated sediment production and transport processes.

Müller, Johann; Gärtner-Roer, Isabelle; Kenner, Robert; Thee, Patrick; Morche, David

2014-08-01

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Congenital vertical talus in four generations of the same family  

International Nuclear Information System (INIS)

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.)

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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

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Fresh-frozen osteochondral allograft reconstruction of a giant cell tumor of the talus.  

Science.gov (United States)

The use of fresh-frozen osteochondral allografts has been reported for the treatment of talar fractures, osteochondral lesions, and tumors of the calcaneus. Currently, we are unaware of any reports in the literature addressing the use of fresh-frozen osteochondral allograft for the treatment of giant cell tumors in the talus. We report our attempt to eradicate an aggressive giant cell tumor of the talus while minimizing morbidity and loss of function via reconstruction with a fresh-frozen osteochondral allograft. This is the first report in the literature to propose such a treatment option for giant cell tumors in the talus. The patient was informed that a report of this case would be submitted for publication. PMID:17466239

Schoenfeld, Andrew J; Leeson, Mark C; Grossman, Jordan P

2007-01-01

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Impact of land-use change on soil degradation by establishment of terraces with subtropical orchards in sloping areas (Granada, SE Spain)  

International Nuclear Information System (INIS)

In the coast of Granada, an intensive irrigated agriculture based on subtropical crops has been established. These trees have been planted in highly sloped areas, by the construction of terraces. In this fragile Mediterranean agroecosystem, the removal of native spontaneous vegetation cover and substitution by orchards, increase the susceptibility to soil degradation and eventually brings up the destruction of these structures by rainfall events. To study this net change, we monitored the soil loss and runoff over a two-year period in the taluses of terraces with a mature mango (Mangifera indica L.) orchard. The studied treatments were bare soil (BS) and spontaneous vegetation (NSV), each twice replicated. The erosion plots were 4 m x 4 m in area and were located in the taluses of orchard in the taluses of orchard terraces (65 degree centigrade slope). The average annual soil loss by erosion for BS and NSV was 2.5 and 0.3 Mg ha-1 yr-1, and for runoff 34.1 and 6.8 mm yr-1, respectively. Therefore, soil erosion and runoff from BS plot were 8- and 5-times higher than in NSV, showing the importance of plant covers in the taluses of terraces in reducing this impact. Thus, the removal of plant cover from the taluses under these conditions, represent a high risk of slump and collapse, causing serious environmental and economic problems for farmers of subtropical crops. (Author) 11 refs.

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Symptomatic Osseous Abnormalities at the Posteromedial Tubercle of the Talus: Magnetic Resonance Imaging Features.  

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Osseous alterations adjacent to the posteromedial tubercle of the talus that lead to posterior ankle impingement and their imaging findings have been much less well described than alterations of the posterolateral tubercle. We present 5 cases of osseous abnormalities at the posteromedial tubercle of the talus depicted on magnetic resonance imaging in subjects with chronic symptoms at this location, with no history of local trauma, who had presented with posteromedial mechanical pain and/or tarsal tunnel syndrome. The symptoms were related to mechanical changes of the bony and soft tissue structures, leading to posterior impingement, and to neurovascular bundle entrapment at the tarsal tunnel, leading to tarsal tunnel syndrome. PMID:25128315

Skaf, Abdalla Y; Olivotti, Bruna; Pecci-Neto, Luis; Yamada, André F; Crema, Michel D

2014-08-12

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Anterior tarsal tunnel syndrome secondary to missed talus fracture: a case report.  

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The anterior tarsal tunnel syndrome (ATTS) has first been described by Kopell and Thompson in 1963. The anterior tarsal tunnel is formed by the fascia lining the inferior extensor retinaculum and talus as well as the navicular bone. Many ATTS cases with various etiologies have been reported since the first description. We report here an ATSS case resulting from a fibro-osseous structure that occurred after a missed talus fracture. The ATTS diagnosis can be made with a comprehensive clinical neurological examination and electrophysiological study. The treatment is based on the underlying etiology, while surgery is the most common treatment providing successful outcomes in the long term. PMID:21534215

Cetinkal, Ahmet; Topuz, Kivanc; Kaya, Serdar; Colak, Ahmet; Demircan, Mehmet Nusret

2011-01-01

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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.

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

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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  

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Full Text Available 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.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 orthopedic 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.

Madson Lobato Drummond Filho

2012-01-01

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Case report 533: Tuberculosis of calcaneus and talus with negative tuberculin skin test  

International Nuclear Information System (INIS)

A case has been presented of a 6-year-old boy, of Pakistanian origin, with tuberculous osteomyelitis in the left calcaneous and talus. Such infections are a result of hematogenous seeding from a primary focus. Despite the existence of a previous infection, and despite 6 months of focal symptoms, the tuberculin skin test was negative. (orig./GDG)

36

Trabecular bone anisotropy and orientation in an Early Pleistocene hominin talus from East Turkana, Kenya.  

Science.gov (United States)

Among the structural properties of trabecular bone, the degree of anisotropy is most often found to separate taxa with different habitual locomotor modes. This study examined the degree of anisotropy, the elongation, and primary orientation of trabecular bone in the KNM-ER 1464 Early Pleistocene hominin talus as compared with extant hominoid taxa. Modern human tali were found to have a pattern of relatively anisotropic and elongated trabeculae on the lateral aspect, which was not found in Pan, Gorilla, Pongo, or KNM-ER 1464. Trabecular anisotropy in the fossil talus most closely resembled that of the African apes except for a region of high anisotropy in the posteromedial talus. The primary orientation of trabeculae in the anteromedial region of KNM-ER 1464 was strikingly different from that of the great apes and very similar to that of modern humans in being directed parallel to the talar neck. These results suggest that, relative to that of modern humans, the anteromedial region of the KNM-ER 1464 talus may have transmitted body weight to the midfoot in a similar manner while the lateral aspect may have been subjected to more variable loading conditions. PMID:23601236

Su, Anne; Wallace, Ian J; Nakatsukasa, Masato

2013-06-01

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Impact of erosion in the taluses of subtropical orchard terraces  

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The coast of the provinces of Granada and Malaga (SE Spain) are economically important areas for the subtropical fruit cultivation. The climate is characterized by heavy periodic rainfall, which is one of the main factors responsible for soil erosion in this agroecosystem. However, the erosion depends on a host of factors, including soil, topography, cropping and soil-conservation techniques. The most widely taken soil-conservation measure taken on steeply sloped coastal mountains in the zone...

Duran Zuazo, V. H.; Ruiz, J. A.; Raya, A. M.; Tarifa, D. F.

2005-01-01

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Skeletal Muscle Contractile Gene (TNNT3, MYH3, TPM2) Mutations Not Found in Vertical Talus or Clubfoot  

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Arthrogryposis presents with lower limb contractures that resemble clubfoot and/or vertical talus. Recently, mutations in skeletal muscle contractile genes MYH3 (myosin heavy chain 3), TNNT3 (troponin T3), and TPM2 (tropomyosin 2) were identified in patients with distal arthrogryposis DA2A (Freeman-Sheldon syndrome) or DA2B (Sheldon-Hall syndrome). We asked whether the contractile genes responsible for distal arthrogryposis are also responsible for cases of familial clubfoot or vertical talus...

Gurnett, Christina A.; Alaee, Farhang; Desruisseau, David; Boehm, Stephanie; Dobbs, Matthew B.

2009-01-01

39

Aggressive Giant Cell Tumour of Talus with Pulmonary Metastasis-A Rare Presentation  

Science.gov (United States)

Giant cell tumour (GCT) is a primary benign neoplasm of bone. It is classically described as a locally invasive tumour that occurs close to the joint of a mature bone. It accounts for 5% of all skeletal tumours. It usually originates from long bones. Giant Cell Tumour of the small bones of the hand and foot are relatively uncommon. Giant Cell Tumour of talus is a rare occurrence. We report a rare presentation of giant cell tumour of the talus in a 62-year-old farmer treated by talectomy and tibiocalcaneal fusion, who later presented with features suggestive of recurrence and secondaries in chest within six months following surgical resection of the primary. Below knee amputation was performed to manage the recurrence. At two years follow-up the patient showed no further progression of pulmonary metastasis or local recurrence. PMID:25177585

Sharma, P Ravi; Ram, G Santhosh; Kumar, P Varun

2014-01-01

40

Outcomes are favorable after arthroscopic treatment of osteochondritis dissecans of the talus.  

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Arthroscopic treatment of osteochondritis dissecans (OCD) of the talus has resulted in outcomes as good as, or better than, those after arthrotomy. We noted a lack of prospective studies investigating the outcomes of arthroscopic treatment. As such, we conducted a prospective study investigating the functional outcomes, pain scores, patient satisfaction, and expectation scores of patients undergoing arthroscopic treatment of OCD of the talus, hypothesizing that these patients would have good outcomes and satisfaction. A total of 61 patients underwent arthroscopic chondroplasty, removal of loose bodies, and microfracture for OCD of the talus and completed ?1 year of follow-up. We evaluated patients pre- and postoperatively at 6 and 12 months using the Ankle-Hindfoot score, visual analog scale for pain, and Medical Outcomes Study short-form 36 questionnaires. We also evaluated the patients' expectations and satisfaction. The mean Ankle-Hindfoot score improved significantly from 53.0 ± 14.3 points preoperatively to 77.8 ± 19.1 at 6 months and 83.1 ± 18.3 at 12 months after arthroscopic treatment (p final follow-up visit were excellent for 30 (49%), good for 6 (10%), fair for 18 (30%), and poor for 7 (11%). The patients also experienced significant improvement in the visual analog scale score and physical component score of the short-form 36 questionnaire (p < .001). Of the 61 patients, 67% had their expectations fulfilled and 74% were satisfied with their surgery at 12 months of follow-up. Arthroscopic treatment of OCD of the talus continues to be a successful procedure to alleviate pain and loss of function. It is also associated with improvements to quality of life and good patient satisfaction. PMID:25441271

Goh, Graham Seow Hng; Bin Abd Razak, Hamid Rahmatullah; Mitra, Amit Kanta

2015-01-01

 
 
 
 
41

[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

42

Estimação dos parâmetros do modelo do motor de indução usando o algoritmo Talus  

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Full Text Available In this paper, the algorithm Talus is applied to problem of parameter estimation of induction motor. The solution of the estimation problem is achieved minimizing a quadratic cost function. The data source used in the algorithm is the measured value of current end power in standard laboratory. The estimated parameters are compared with classical test (no-load and locked rotor either by simulation and experimentally

Eurico Souza Filho Bezerra de

2004-01-01

43

Estimação dos parâmetros do modelo do motor de indução usando o algoritmo Talus  

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In this paper, the algorithm Talus is applied to problem of parameter estimation of induction motor. The solution of the estimation problem is achieved minimizing a quadratic cost function. The data source used in the algorithm is the measured value of current end power in standard laboratory. The estimated parameters are compared with classical test (no-load and locked rotor) either by simulation and experimentally

Eurico Souza Filho Bezerra de

2004-01-01

44

Assessment of talus deformity by three-dimensional MRI in congenital clubfoot  

International Nuclear Information System (INIS)

Purpose: To evaluate the morphological deformity of talus in congenital clubfoot by three-dimensional MRI. Material and method: Subjects were five patients (two male, three female, mean age 5 months) with unilateral congenital clubfoot. Magnetic resonance imaging was performed of both feet using 1.5 T magnet. Based on the resulting magnetic resonance imaging volume data, a three-dimensional surface bone model was reconstructed by the Marching Cubes method. The long axis of the reconstructed model was determined, and in relation to the standard planes including this axis, the degree of talar head and neck deviation, and the relative positioning of the talus and navicular in the talonavicular joint were compared between normal foot and clubfoot. Result: The talar head and neck angle in relation to the talus exhibited significant medial deviation in the clubfoot, but the degree of plantar deviation of the talar head and neck did not show significance. The navicular was located more medially in clubfoot than in normal foot. The volume of the total talar and of the ossific nucleus for the clubfoot was smaller than that for the normal foot. Conclusion: The assessment technique presented herein was shown to be useful in ascertaining the various pathological characteristics associated with clubfoot

45

Assessment of talus deformity by three-dimensional MRI in congenital clubfoot  

Energy Technology Data Exchange (ETDEWEB)

Purpose: To evaluate the morphological deformity of talus in congenital clubfoot by three-dimensional MRI. Material and method: Subjects were five patients (two male, three female, mean age 5 months) with unilateral congenital clubfoot. Magnetic resonance imaging was performed of both feet using 1.5 T magnet. Based on the resulting magnetic resonance imaging volume data, a three-dimensional surface bone model was reconstructed by the Marching Cubes method. The long axis of the reconstructed model was determined, and in relation to the standard planes including this axis, the degree of talar head and neck deviation, and the relative positioning of the talus and navicular in the talonavicular joint were compared between normal foot and clubfoot. Result: The talar head and neck angle in relation to the talus exhibited significant medial deviation in the clubfoot, but the degree of plantar deviation of the talar head and neck did not show significance. The navicular was located more medially in clubfoot than in normal foot. The volume of the total talar and of the ossific nucleus for the clubfoot was smaller than that for the normal foot. Conclusion: The assessment technique presented herein was shown to be useful in ascertaining the various pathological characteristics associated with clubfoot.

Itohara, T. E-mail: tomonobu@ort.med.osaka-u.ac.jp; Sugamoto, K.; Shimizu, N.; Ohno, I.; Tanaka, H.; Nakajima, Y.; Sato, Y.; Yoshikawa, H

2005-01-01

46

Transient bone marrow edema of the talus: MR imaging findings in five patients  

International Nuclear Information System (INIS)

Objective: To describe the MR findings of transient bone marrow edema (TBME) of the talus and to address the differential diagnostic considerations. Design and patients: The imaging findings of TBME of six tali were retrospectively reviewed in five patients with a clinical history of pain without trauma. Inclusion criteria were MR imaging findings that, when compared with clinical data and results of follow-up assessment, allowed the diagnosis of TBME. MR imaging, standard radiography, and bone scintigraphy were performed. The images were reviewed with particular attention to the pattern and distribution of abnormal marrow signal intensity as well as associated findings. Results: In four cases the entire talus was involved, and in two cases only a portion of the bone was affected. No fractures were detected. MR imaging demonstrated diffuse decreased signal intensity of the marrow on T1-weighted images with corresponding increased signal intensity on T2-weighted images. In all six cases MR imaging detected associated findings, which included joint effusion and soft tissue edema. All patients improved clinically with conservative therapy over a period of 6 months to 1 year. Conclusions: Although unusual, TBME can involve the talus. Marrow edema without evidence of a fracture and in the absence of history of trauma is a characteristic MR imaging feature, allowing confident diagnosis and institution of conservative therapy. (orig.))

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Intraosseous ganglion of the talus treated with the talonavicular joint approach without exposing the ankle joint.  

Science.gov (United States)

Intraosseous ganglion, which is generally seen in metaphyseal-epiphyseal regions of long bones, is not a rare disorder. It is extremely rare in the talus, however. Differential diagnosis of a cystic talar lesion should include enchondroma, chondroblastoma, giant cell tumor, and unicameral bone cyst. This article presents a case of intraosseous ganglion of the talus in a 38-year-old woman treated with a new surgical approach and technique. The patient had mild ankle pain at the arc of motion in her right ankle that increased with activity. Radiographs and magnetic resonance images showed a cystic lesion in the medial side of the talar dome. It was treated by curettage and autocorticocancellous bone grafting through an opening in the talonavicular joint without disturbing the intact talar dome cartilage. One month after the operation, the patient had an excellent clinical outcome. This approach and technique can be used to treat other lesions of the talus that do not involve the joint space. PMID:17901351

Cebesoy, Oguz

2007-01-01

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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

49

Groundwater flow and storage within an alpine meadow-talus complex  

Directory of Open Access Journals (Sweden)

Full Text Available The different types of geological deposits and rock formations found in alpine watersheds play key roles in regulating the rate and timing of runoff to mountain rivers. Talus and alpine meadows are dominant features in these areas, but scant data exist for their capacity to store and transmit groundwater. To gain further understanding of these processes, we have undertaken a combined geophysical and hydrological study of a small (2100 m2 alpine meadow and surrounding talus within the Lake O'Hara watershed in the Canadian Rockies. Several intersecting ground-penetrating radar (GPR and electrical resistivity tomography (ERT profiles and a seismic refraction profile were acquired to map the thickness of the talus and to image the topography of the bedrock basin that lies under the meadow. From analysis of the GPR and seismic profiles, we estimate that the talus deposits are relatively thin (<6 m. Combined interpretations from the GPR and ERT data show that the fine-grained sediment, that the meadow basin is comprised of, has a total volume of ca. 3300 m3 and has a maximum thickness of ca. 4 m. Annual snow surveys and stream gauging reveal that the total input volume of snowmelt and rainfall to the meadow basin is several times larger than its groundwater storage capacity, giving rise to low total-dissolved species concentrations (14–21 mg/L within the meadow groundwater. Observations from four piezometers established on the meadow show that the water table fluctuates rapidly in response to spring snowmelt and precipitation events but otherwise maintains a relatively stable depth of 0.3–0.4 m below the meadow surface during summer months. A slug test performed on one of the piezometers indicated that the saturated hydraulic conductivity of the shallow meadow sediments is 2.5×10?7 m/s. We suggest that a bedrock saddle imaged underneath the southern end of the meadow forms a natural constriction to subsurface flow out of the basin and helps to maintain the stable water-table depth.

A. F. McClymont

2010-02-01

50

Groundwater flow and storage within an alpine meadow-talus complex  

Directory of Open Access Journals (Sweden)

Full Text Available The different types of geological deposits and rock formations found in alpine watersheds play key roles in regulating the rate and timing of runoff to mountain rivers. Talus and alpine meadows are dominant features in these areas, but scant data exist for their capacity to store and transmit groundwater. To gain further understanding of these processes, we have undertaken a combined geophysical and hydrological study of a small (2100 m2 alpine meadow and surrounding talus within the Lake O'Hara watershed in the Canadian Rockies. Several intersecting ground-penetrating radar (GPR and electrical resistivity tomography (ERT profiles and a seismic refraction profile were acquired to map the thickness of the talus and to image the topography of the bedrock basin that underlies the meadow. From analysis of the GPR and seismic profiles, we estimate that the talus deposits are relatively thin (<6 m. Combined interpretations from the GPR and ERT data show that the fine-grained sediment comprising the meadow basin has a total volume of ca. 3300 m3 and has a maximum thickness of ca. 4 m. Annual snow surveys and stream gauging reveal that the total input volume of snowmelt and rainfall to the meadow basin is several times larger than its groundwater storage capacity, giving rise to low total-dissolved species concentrations (14–21 mg/L within the meadow groundwater. Observations from four piezometers established on the meadow show that the water table fluctuates rapidly in response to spring snowmelt and precipitation events but otherwise maintains a relatively stable depth of 0.3–0.4 m below the meadow surface during summer months. A slug test performed on one of the piezometers indicated that the saturated hydraulic conductivity of the shallow meadow sediments is 2.5×10?7 m/s. We suggest that a bedrock saddle imaged underneath the southern end of the meadow forms a natural constriction to subsurface flow out of the basin and helps to maintain the stable water-table depth.

A. F. McClymont

2010-06-01

51

Tarsal Tunnel Syndrome Secondary to an Unreported Ossicle of the Talus: A Case Report.  

Science.gov (United States)

Tarsal tunnel syndrome (TTS) is a compression neuropathy of the posterior tibial nerve in the tarsal tunnel. In about 80% of patients, a specific cause can be identified for TTS. We present a case of TTS secondary to an ossicle in close relation to the talus that, to our knowledge, has not previously been reported. A 26-year-old male presented with left ankle and foot pain that increased with activity and playing football. He had a tingling sensation and paresthesia in the sole and medial border of the foot along the distribution of the medial and lateral plantar nerves. Clinically, he had hard swelling at the floor of the tarsal tunnel, and Tinel's sign was positive. Computed tomography showed an accessory ossicle articulating with the posteromedial aspect of the talus, separating the flexor digitorum longus and flexor hallucis longus tendons, with tenosynovitis of the tibialis posterior, flexor digitorum longus and flexor hallucis longus tendons. Surgical release of the tarsal tunnel and excision of the ossicle were performed. Postoperatively, the patient showed dramatic improvement and had no complications or recurrence of symptoms after 8 months of follow-up. More interestingly, to the best of our knowledge, this ossicle has not been previously reported to cause TTS. PMID:25441278

Sweed, Tamer Ahmed; Ali, Seyed Asghar; Choudhary, Surabhi

2014-10-31

52

Permafrost in vegetated scree slopes below the timberline - characterization of thermal properties and permafrost conditions by temperature measurements and geoelectrical monitoring  

Science.gov (United States)

Discontinuous alpine permafrost is expected to exist at altitudes above 2400m a.s.l. at mean annual air temperatures (MAAT) of less than -1°C. Below timberline only a few sites are known, where sporadic permafrost exists in vegetated talus slopes with positive MAAT. Aim of the study is to characterize permafrost-humus interaction, the thermal regime and its influence on temporal and spatial permafrost variability. Results of geophysical and thermal measurements from three talus slopes, located in the Swiss Alps (Engadin, Appenzell) at elevations between 1200 and 1800m a.s.l. with MAAT between 2.8°C and 5.5°C are presented. Parent rock-material of the slopes are granite (Bever Valley, Engadin) and dolomite (Susauna Valley, Engadin; Brüeltobel, Appenzell). Joint application of electrical resistivity tomography (ERT) and refraction seismic tomography (RST) is used to detect and characterize permafrost. To observe temporal and spatial variability in ice content and characteristics year-around geoelectrical monitoring and quasi-3D ERT are used. A forward modeling approach has been applied to validate the results of geoelectrical monitoring. A number of temperature data loggers were installed in different depth of the humus layer and in different positions of the slope to monitor the ground thermal regime. Isolated permafrost has been detected by the combination of ERT and RST in the lower parts of the investigated talus slopes. Results from geophysical measurements and monitoring indicate a high spatial and temporal variability in ice content and ice characteristics (temperature, density, content of unfrozen water) for all sites. A distinct rise of resistivities between November and December indicates a decrease of unfrozen water content, caused by a pronounced cooling in the lower parts of the slope. Decreasing ice content and extent of the permafrost lenses can be observed in decreasing seismic velocities from 2600m/sec in spring to only 1500m/sec in October. Ice characteristics, ice content and extent of permafrost lenses depend on the thermal regime, induced by characteristics of surface (humus, vegetation) and subsurface (parental rock material) material as well as thermal effects, with an inversive air flow inside the talus slope of cold air inflow in winter in the lower parts and cold air outflow in summer through the same vents (chimney effect), a theory that has been proven by temperature measurements in the Brüeltobel and the Susauna Valley. While the dolomitic talus slopes are relatively homogenous concerning surface and subsurface material, showing a consistent thick humus cover, the granitic site shows a small-scale heterogeneity of different humus forms and thicknesses as well as size of granitic boulders, influencing the thermal regime. Temperatures in the humus profile are very constant for the dolomitic sites, reflecting the insulation capability of the humus cover, with temperatures in August around 3°C at 30cm depth (mean air temperature in August 12°C). Humus temperatures (30cm depth) in the Bever Valley vary strongly between areas with consistent humus cover (1-2°C in August) and areas with coarse, uncovered boulders, where temperatures show a stronger coupling to air temperatures. While the chimney effect has strong influence on the ground thermal regime of the dolomitic sites, for some parts of the granitic slope in the Bever Valley the theory has to be expanded towards a continuous air exchange with the atmosphere, for areas where the insulation capability of the humus cover is highly disturbed along large parts of the talus slope.

Schwindt, Daniel; Kneisel, Christof

2010-05-01

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Modelling the lava dome extruded at Soufriere Hills Volcano, Montserrat, August 2005-May 2006. Part II, rockfall activity and talus deformation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

During many lava dome-forming eruptions, persistent rockfalls and the concurrent development of a substantial talus apron around the foot of the dome are important aspects of the observed activity. An improved understanding of internal dome structure, including the shape and internal boundaries of the talus apron, is critical for determining when a lava dome is poised for a major collapse and how this collapse might ensue. We consider a period of lava dome growth at the Soufrière Hills Volca...

Hale, A. J.; Calder, E. S.; Loughlin, S. C.; Wadge, G.; Ryan, G. A.

2009-01-01

54

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.)

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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

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Unrecognized fracture of the posteromedial process of the talus--a case report and review of literature.  

Science.gov (United States)

In this report, we present a rare case of an initially unrecognized fracture of the posteromedial process of the talus sustained in a seldom reported position of dorsiflexion and supination of the foot. Fractures of the posteromedial process of the talus are very rare and represent an important diagnostic problem. Difficult x-ray visualization makes these fractures often misdiagnosed as ankle sprains. Complications due to this kind of fractures can include serious consequences such as avascular osteonecrosis, tarsal tunnel syndrome, post-traumatic osteoarthritis, or chronic pain. Timely diagnosis represents an important factor in the development of these conditions. A heightened awareness in examining ankle traumas with specific patient history details is of great importance. The most common mechanism of injury includes dorsiflexion and pronation of the foot. However, in an increasing number of cases alternative mechanisms have been described, all including high-energy impacts. Our patient sustained a fracture of the posteromedial process of the talus in dorsiflexion and supination with high-energy impact due to a 3-m fall. The patient was treated with excision of the fragment six months after the injury, and 18 months after the surgery the patient returned to his normal daily activities with significantly less pain in the posteromedial part of the ankle. PMID:21462822

Rogosi?, Srdan; Bojani?, Ivan; Bori?, Igor; Tudor, Anton; Srdoc, Dubravka; Sestan, Branko

2010-09-01

57

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

58

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

59

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

60

MRI-guided percutaneous retrograde drilling of osteochondritis dissecans of the talus: a feasibility study  

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study was to evaluate the feasibility of MRI guidance for percutaneous retrograde drilling in the treatment of osteochondritis dissecans of the talus (OCDT). Four patients, one juvenile and three adults, with one OCDT lesion each and persisting ankle pain after conservative treatment, were treated with MRI-guided retrograde drilling. All lesions were stable and located in the middle or posterior medial third of the talar dome. Pain relief and the ability to return to normal activities were assessed during clinical follow-up. MRI and plain film radiographs were used for imaging follow-up. Technical success was 100 % with no complications and with no damage to the overlying cartilage. All patients experienced some clinical benefit, although only one had complete resolution of pain and one had a relapse leading to surgical treatment. Changes in the pathological imaging findings were mostly very slight during the follow-up period. MRI guidance seems accurate, safe and technically feasible for retrograde drilling of OCDT. Larger series are needed to reliably assess its clinical value. (orig.)

Kerimaa, Pekka; Ojala, Risto; Markkanen, Paula; Tervonen, Osmo; Blanco Sequeiros, Roberto [Oulu University Hospital, Department of Radiology, Oulu (Finland); Sinikumpu, Juha-Jaakko; Korhonen, Jussi [Oulu University Hospital, Department of Paediatric Surgery, Oulu (Finland); Hyvoenen, Pekka [Oulu University Hospital, Department of Surgery, Oulu (Finland)

2014-07-15

 
 
 
 
61

Iveagh Slopes Geodiversity Profile  

...complex of Slieve Croob and the structural depression that underlies and defines Strangford Lough. Below...which radiates from the centre of the depression. The upper slopes of Knockiveagh are littered...

62

Antidunes on steep slopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

When rates of subcritical flow are increased on gentle slopes, the bed successively produces ripples, dunes, and flat beds. Antidunes (defined here as all bed undulations for which the surface gravity waves are in phase with the bed profile) appear only in high flow rates and may be found in some extreme natural flow events. Inversely, on steep slopes flume experiment (S ? 1% approximately) flows are supercritical and antidunes are observed to appear just after the beginning of sediment...

Recking, A.; Bacchi, V.; Naai?m, M.; Frey, P.

2009-01-01

63

Effect of simulated lateral process talus "fracture excision" on its ligamentous attachments.  

Science.gov (United States)

Recent epidemiologic studies highlight lateral talar process fractures as snowboarder's fracture or snowboarder's ankle. Snowboarding is the fastest growing sport worldwide, so lateral talar process fractures are increasing in frequency and mandating a more careful assessment of injury patterns, surrounding tissue involvement, and treatment strategy. In this study, we evaluated the effects of lateral talar process fracture on the footprints of 3 lateral stabilizing ligaments of the ankle and subtalar joint-the lateral talocalcaneal ligament (LTCL), the anterior talofibular ligament (ATFL), and the posterior talofibular ligament (PTFL). The musculotendinous structures from 10 fresh cadaveric limbs were removed and the distal fibula reflected to provide visualization of the lateral talar process and ligamentous attachments. Length and width of the LTCL, ATFL, and PTFL footprints on the lateral process of the talus were measured with calipers before and after removal of a 1-cm(3) simulated fracture fragment. Relative changes in the attachment site areas for the 3 ligaments were determined. Mean pre-excision footprint areas were 80.57 mm(2) (LTCL), 224.38 mm(2) (ATFL), and 394.18 mm(2) (PTFL); mean postexcision footprint areas were 2.10 mm(2) (LTCL), 194.89 mm(2) (ATFL), and 335.18 mm(2) (PTFL); and mean decreases calculated as percentages of the original areas were 97.5% +/- 3.5% (LTCL), 11.7% +/- 13.0% (ATFL), and 14.3% +/- 12.3% (PTFL). Removal of a 1-cm(3) bony fragment from the lateral talar process involves 3 of the major lateral stabilizing ligaments: approximately 100% of LTCL and approximately 10% to 15% of ATFL and PTFL. PMID:19584991

Langer, Phillip; Nickisch, Florian; Spenciner, David; DiGiovanni, Christopher

2009-05-01

64

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

65

Enucleación medial de astrágalo abierta: Evolución a medio plazo Medial dislocation of the talus: Medium term evolution  

Directory of Open Access Journals (Sweden)

Full Text Available Paciente de 57 años con enucleación abierta medial del astrágalo izquierdo, con fractura suprasindesmal de peroné, por traumatismo indirecto. Se realizó lavado, limpieza del astrágalo y partes blandas, Friedrich, reducción, fijación con agujas de kirschner, sutura del ligamento deltoideo y osteosíntesis del peroné. No hubo infección superficial ni profunda postoperatoria. Permaneció seis semanas de inmovilización y tres meses en descarga. Dos años después no había signos radiológicos de necrosis avascular. En gammagrafía ósea realizada a los 18 meses de la lesión se observaba necrosis avascular parcial astragalina. Tres años después de la lesión realizaba vida normal, sin dolor en reposo pero sí a la marcha y movilidad con limitación de la dorsiflexión (-20º. Cinco años y medio después de la lesión presentaba hundimiento de cúpula astragalina por la necrosis avascular con sintomatología dolorosa a la marcha y diástasis tibio-peronea distal, que requirió realizar artrodesis tibio-astragalina.Fifty-seven year old patient with open medial dislocation of the left talus, with suprasyndesmotic fracture of the fibula, due to indirect traumatism. The following were carried out: washing, cleaning the talus and the soft parts, Friedrich, reduction, fixing with Kirschner needles, suture of the deltoid ligament, and osteosynthesis of the fibula. There were neither surface nor deep post-operational infections. The patient underwent six weeks of immobilisation and spent three months on discharge. Two years later there were no radiological signs of avascular necrosis. In the osseous gammagraphy carried out 18 months after the lesion, partial avascular necrosis of the talus was observed. Three years after the lesion, the patient was able to carry out a normal life, without pain in repose but with pain whilst moving, and mobility with limitation of dorsoinflection (-20º. Five and a half years after the lesion, the patient presented sinking of the talar dome due to avascular necrosis, with painful symptomatology whilst moving, and tibiofibular distal diastasis, which required ankle arthrodesis.

S. García Mata

2009-04-01

66

Functional anatomy of the calcaneum and talus in Cercopithecinae (Mammalia, Primates, Cercopithecidae  

Directory of Open Access Journals (Sweden)

Full Text Available Among the species of the order Primates exist a huge variety of forms and habitats. This heterogeneity has encouraged the evolution and development of a great number of locomotor adaptations to different environments. Thus, nowadays there are both arboreal and terrestrial groups within the order. The subfamily Cercopithecinae present taxa with both kinds of locomotor behaviours, although the most of them are adapted to a ground life-style. This group probably has an arboreal ancestor and its radiation is relatively recent. Consequently, species belonged to this group present mixed features or sometimes not too much derived ones. Likewise, it is important the fact that the evolutionary history and phylogeny of the group could influence in some characteristics. Both the calcaneum and the talus are two of the largest bones of the foot and are good for inferring the kind of locomotion. For this reason, it has been used these two tarsal bones to study the morphology of eight species of cercopithecines and then deduce functional implications of the kind of locomotion.

Dentro del orden Primates existe una gran variedad de especies distribuidas a lo largo de hábitats muy diversos. Dicha heterogeneidad ha fomentado la evolución y desarrollo de un gran número de adaptaciones locomotoras a los diferentes ambientes en los que habitan. Así, existen en la actualidad tanto grupos arborícolas como terrestres. La subfamilia Cercopithecinae agrupa una serie de taxones que representan ambos comportamientos locomotores, aunque la mayoría de las especies están adaptadas a una vida en el suelo. Se supone que este grupo desciende de un ancestro arborícola y que su radiación es relativamente reciente. En consecuencia, las especies de este grupo presentan características mixtas o poco derivadas en algunas ocasiones. Asimismo, es importante tener en cuenta la influencia que la herencia filogenética puede tener sobre alguno de estos rasgos. El calcáneo y el astrágalo son dos de los huesos más grandes del pie y ambos son buenos indicadores del tipo de locomoción. Por este motivo, se han utilizado estos dos tarsales para llevar a cabo el estudio de la morfología de ocho especies de cercopitecoideos, de tal manera que luego se ha podido hacer una serie de inferencias funcionales en cuanto al tipo de locomocón de las mismas.

Pina, M.

2011-12-01

67

A novel mutation in TNNT3 associated with Sheldon-Hall syndrome in a Chinese family with vertical talus.  

Science.gov (United States)

Distal arthrogryposis (DA) is a group of rare, clinically and genetically heterogeneous disorders primarily characterized by congenital contractures of the limb joints. Recently, mutations in genes encoding the fast-twitch skeletal muscle contractile myofibers complex, including troponin I2 (TNNI2), troponin T3 (TNNT3), tropomyosine 2 (TPM2), and embryonic myosin heavy chain 3 (MYH3), and the slow-twitch skeletal muscle myosin binding protein C1 (MYBPC1) were confirmed to cause DA1, DA2A, and DA2B. DA2B, or Sheldon-Hall syndrome (SHS; MIM 601680), is intermediate to DA1 and DA2A, or Freeman-Sheldon syndrome (FSS; MIM193700), and shows prominent facial traits. This report describes a Chinese family with SHS over three generations in which all affected individuals showed vertical talus and one demonstrated preauricular tags on the face. Linkage analysis and PCR sequencing revealed a novel substitute mutation at a hot-spot site in TNNT3 (c.187C > T; p.R63C). This mutation was confirmed to cosegregate with the DA phenotype in affected individuals. SIFT and PolyPhen analyses suggest that the mutation is pathogenic. We report this mutation in TNNT3 and speculate that bilateral vertical talus, or severe clubfoot, might be a special characteristic for cases with the TNNT3 R63C mutation. PMID:21402185

Zhao, Ning; Jiang, Miao; Han, Weitian; Bian, Chaoying; Li, Xuefu; Huang, Fang; Kong, Qi; Li, Jianxin

2011-01-01

68

Enucleación medial de astrágalo abierta: Evolución a medio plazo / Medial dislocation of the talus: Medium term evolution  

Scientific Electronic Library Online (English)

Full Text Available SciELO Spain | Language: Spanish Abstract in spanish Paciente de 57 años con enucleación abierta medial del astrágalo izquierdo, con fractura suprasindesmal de peroné, por traumatismo indirecto. Se realizó lavado, limpieza del astrágalo y partes blandas, Friedrich, reducción, fijación con agujas de kirschner, sutura del ligamento deltoideo y osteosínt [...] esis del peroné. No hubo infección superficial ni profunda postoperatoria. Permaneció seis semanas de inmovilización y tres meses en descarga. Dos años después no había signos radiológicos de necrosis avascular. En gammagrafía ósea realizada a los 18 meses de la lesión se observaba necrosis avascular parcial astragalina. Tres años después de la lesión realizaba vida normal, sin dolor en reposo pero sí a la marcha y movilidad con limitación de la dorsiflexión (-20º). Cinco años y medio después de la lesión presentaba hundimiento de cúpula astragalina por la necrosis avascular con sintomatología dolorosa a la marcha y diástasis tibio-peronea distal, que requirió realizar artrodesis tibio-astragalina. Abstract in english Fifty-seven year old patient with open medial dislocation of the left talus, with suprasyndesmotic fracture of the fibula, due to indirect traumatism. The following were carried out: washing, cleaning the talus and the soft parts, Friedrich, reduction, fixing with Kirschner needles, suture of the de [...] ltoid ligament, and osteosynthesis of the fibula. There were neither surface nor deep post-operational infections. The patient underwent six weeks of immobilisation and spent three months on discharge. Two years later there were no radiological signs of avascular necrosis. In the osseous gammagraphy carried out 18 months after the lesion, partial avascular necrosis of the talus was observed. Three years after the lesion, the patient was able to carry out a normal life, without pain in repose but with pain whilst moving, and mobility with limitation of dorsoinflection (-20º). Five and a half years after the lesion, the patient presented sinking of the talar dome due to avascular necrosis, with painful symptomatology whilst moving, and tibiofibular distal diastasis, which required ankle arthrodesis.

S., García Mata; A., Hidalgo Ovejero; F., Martínez de Lecea.

2009-04-01

69

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 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. PMID:24891587

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

2014-06-01

70

Using Submarine Landslides to Predict Slope Stability  

Science.gov (United States)

Students use detailed bathymetric maps to find submarine landslides and compare the slope of these slides to the slope of hills near school and home. By comparing the slopes they can consider slope failure, especially during earthquakes.

Doan, Shawn

71

Exceptional surgery and boundary slopes  

CERN Document Server

Let X be a norm curve in the SL(2,C)-character variety of a knot exterior M. Let t = || b || / || a || be the ratio of the Culler-Shalen norms of two distinct non-zero classes a, b in H_1(\\partial M, Z). We demonstrate that either X has exactly two associated strict boundary slopes \\pm t, or else there are strict boundary slopes r_1 and r_2 with |r_1| > t and |r_2| < t. As a consequence, we show that there are strict boundary slopes near cyclic, finite, and Seifert slopes. We also prove that the diameter of the set of strict boundary slopes can be bounded below using the Culler-Shalen norm of those slopes.

Ishikawa, M; Shimokawa, K; Ishikawa, Masaharu; Mattman, Thomas W.; Shimokawa, Koya

2002-01-01

72

Géodynamique, colonisation végétale et phytodiversité des talus d'éboulis dans le massif de la Grande Chartreuse (Préalpes françaises du Nord). Caractéristiques géo-écologiques et sensibilité aux changements environnementaux.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Les talus d'éboulis du massif de la Grande Chartreuse retenus par la Directive « Habitats, faune et flore » comme des sites d'intérêt communautaire, abritent de nombreuses espèces rupicoles considérées comme prioritaires. La diversité spécifique de ces talus d'éboulis semble inféodée à leur structure paysagère en mosaïque, dont la dynamique est régie par l'interaction de facteurs topo-climatiques, édaphiques, géomorphologiques, géodynamiques et biologiques, agissant à plu...

Arques, Sylvie

2005-01-01

73

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

74

Contribution of magnetic resonance imaging in the diagnosis of talus skip metastases of Ewing's sarcoma of the calcaneus in a child: a case report  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Introduction Ewing's sarcoma of the calcaneus is rare. About thirty cases with calcaneus involvement have been reported in the literature. Talus skip metastases have rarely been described in the available literature Case presentation We report a case of a 14-year-old Moroccan boy, who presented with Ewing's sarcoma of his right calcaneus, diagnosed by swelling of the calcaneus evolving over a year. Radiography, computed tomography and magnetic resonance...

Fikry Tarik; Madhar Mohammed; Enneddam Hind; Belhadj Zoubida; Jalal Hicham; Essadki Omar; Ousehal Ahmed

2011-01-01

75

Blake's Slope-Intercept Surprise.  

Science.gov (United States)

Describes a student's unique perspective on the algorithm for finding equations of non-vertical lines given one point and the slope. Indicates that students had a better understanding of what they were doing. (KHR)

Misener, Jeff P.

2000-01-01

76

Car Depreciation (rate and slope)  

Science.gov (United States)

The purpose of this activity is for students to use the concept of the rate of depreciation in a real world situation to investigate the relationship between rate and slope. Students create ordered pairs, graph depreciating car values, and calculate rates of depreciation, then identify that the rate of depreciation = slope of the line. Using the equation they then solve for future values and times.

2010-01-01

77

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

78

North Slope (Wahluke Slope) expedited response action cleanup plan  

Energy Technology Data Exchange (ETDEWEB)

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 mi{sup 2} (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.

1994-02-01

79

When does the flat-top talus lesion occur in idiopathic clubfoot: evaluation with magnetic resonance imaging at three months of age.  

Science.gov (United States)

Flat-top talus has been described as a pathologic change secondary to idiopathic clubfoot condition and/or as a direct result of nonoperative manipulation involving forced dorsiflexion and molding of the cartilaginous talus. No definitive study, however, on the etiology and the timing of the flat-top talus deformity has been performed to date. The authors evaluated the magnetic resonance images of eleven patients with idiopathic clubfoot deformities treated with 2 to 3 months of casting to assess if flattening of the talar dome occurred at this age with this amount of casting. All children were 3 months of age, were casted for a maximum of 2 to 3 months, and sedated before MRI examination. The images were evaluated for maximum talar head height, maximum talar body height, and deviation of the talar body from a perfect circle. Maximum talar head height ranged from 4 to 9 mm, maximum talar body height ranged from 6 to 10 mm. Eight of the eleven had maximum talar body measurements 3 to 5mm greater than maximum talar head height. Three of the eleven patients had head and body size of equal proportion. Two of the eleven had a talar body that was within 1 mm of a perfect circle. The remaining nine patients had perfectly round talar bodies. In the senior author's (RSD) experience with treating clubfeet, a substantial increase has been seen at operation in flat-top tali among children that were casted for more than 1 year before surgical correction, compared to children casted for 3 months before surgical correction. The current investigation indicated that although tali of children with clubfeet are abnormally shaped, the talar body remains larger than the talar head and maintains its roundness after two to three months of corrective casting. Maintenance of cast treatment for more than three months may lead to the flat-top talus deformity. The authors recommend surgical intervention following three months of failed manipulation and casting to prevent this deformity. PMID:11428762

Sullivan, R J; Davidson, R S

2001-05-01

80

Radioecological reliability of slope ecosystem  

International Nuclear Information System (INIS)

Natural and technogenic cataclysms taking place in Ukraine bring to the forefront the problem of estimation and forecast of different ecosystems type. Theory and models of the radio capacity and reliability developed by us allow to describe adequately regularities of radionuclide migration and redistribution in slope ecosystems, and carry out mathematical modeling of investigated phenomena. That will give the possibility to use special countermeasures

 
 
 
 
81

Contribution of magnetic resonance imaging in the diagnosis of talus skip metastases of Ewing's sarcoma of the calcaneus in a child: a case report  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Introduction Ewing's sarcoma of the calcaneus is rare. About thirty cases with calcaneus involvement have been reported in the literature. Talus skip metastases have rarely been described in the available literature Case presentation We report a case of a 14-year-old Moroccan boy, who presented with Ewing's sarcoma of his right calcaneus, diagnosed by swelling of the calcaneus evolving over a year. Radiography, computed tomography and magnetic resonance imaging showed an important tumoral process of the calcaneus and talus skip metastases. The diagnosis was confirmed with histology after a biopsy. In spite of amputation and postoperative chemotherapy, our patient died six months later due to secondary respiratory distress after lung metastasis. Conclusion Imaging, especially magnetic resonance, is important in the diagnosis of Ewing sarcoma and skeletal skip metastases. Treatment of Ewing's sarcoma consists of chemotherapy, radiation therapy and surgical resection depending on the stage and extent of the disease. With the exception of lesions in the calcaneus, the prognosis for disease-free survival of Ewing's sarcoma of the foot is excellent.

Fikry Tarik

2011-09-01

82

Double dual slope square rooter  

Directory of Open Access Journals (Sweden)

Full Text Available A circuit which accepts input dc voltage V(I and produce an output voltage V(O = ?V(IV(T by using double dual slope principle is described in this Letter. V(T is a constant voltage which is fixed by two resistors and a power supply voltage. By using precision resistors and a stable constant power supply, an acceptable level of accuracy can be obtained.

Krishnagiri Chinnathambi Selvam

2014-01-01

83

Kuhse, Singer and slippery slopes.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Helga Kuhse and Peter Singer recently examined the view expressed by John Lorber that whereas at times it is permissible to allow severely handicapped infants to die, killing them must never be allowed. In attempting to demonstrate the mistaken nature of Lorber's fear that allowing active infanticide would lead us onto a slippery slope Kuhse and Singer make much use of John Harris's paper in the Journal of Medical Ethics in which he criticised Lorber's views. This paper examines some aspects ...

Fairbairn, G. J.

1988-01-01

84

Computing boundary slopes of 2-bridge links  

CERN Document Server

We describe an algorithm for computing boundary slopes of 2-bridge links. As an example, we work out the slopes of the links obtained by 1/k surgery on one component of the Borromean rings. A table of all boundary slopes of all 2-bridge links with 10 or less crossings is also included.

Hoste, J; Hoste, Jim; Shanahan, Patrick D.

2005-01-01

85

Geotechnical system reliability of slopes  

International Nuclear Information System (INIS)

In slope stability analysis it is customary to search for the critical slip surface considering the conventional factor of safety as an index of stability. With the development of reliability analysis approaches within a probabilistic framework, alternative definitions of the critical slip surface can be adopted. Thus one may define a critical slip surface as one with the lowest reliability index or one with the highest probability of failure. However, it is important to consider the slope stability problem in terms of a system of many potential slip surfaces. For such a system, the calculation of system reliability is appropriate and desirable. In this paper, system reliability bounds are calculated within a probabilistic framework. The 'system reliability' or the 'system probability of failure' must be estimated for comparison with the corresponding reliability or probability of failure with respect to a 'critical' slip surface. The general slope stability problem involving non-zero internal friction angle involves a non-linear performance function. Moreover, the expression for factor of safety is usually inexplicit except for the ordinary method of slices which is not accurate except when 'oe = 0'. This paper addresses the system reliability for inexplicit and non-linear performance functions as well as for linear and explicit ones. Any version of the method of slices may be used although the proposed approach is presented on the basis of the Bishop simplified methon the basis of the Bishop simplified method. It is shown that the upper bound system failure probability is higher than the failure probability associated with a critical slip surface. The difference increases as the coefficient of variation of the shear strength parameters increases

86

Delayed gadolinium-enhanced MRI of cartilage of the ankle joint: Results after autologous matrix-induced chondrogenesis (AMIC)-aided reconstruction of osteochondral lesions of the talus  

International Nuclear Information System (INIS)

Aim: To assess cartilage quality using delayed gadolinium-enhanced magnetic resonance imaging after repair of osteochondral lesions of the talus using autologous matrix-induced chondrogenesis (AMIC). Materials and methods: A three-dimensional (3D) spoiled gradient-echo (SGE) sequence at 3 T was used to obtain quantitative T1 relaxation times before and after Gd-DTPA2 (Magnevist, 0.2 mM/kg bod weight) administration to assess 23 cases of AMIC-aided repair of osteochondral lesions of the talus. Delta relaxation rates (?R1) for reference cartilage (RC) and repair tissue (RT), and the relative delta relaxation rate (r?R1) were calculated. The morphological appearance of the cartilage RT was graded on sagittal dual-echo steady-state (DESS) views according to the “magnetic resonance observation of cartilage repair tissue” (MOCART) protocol. The study was approved by the institutional review board and written consent from each patient was obtained. Results: The AMIC cases had a mean T1 relaxation time of 1.194 s (SD 0.207 s) in RC and 1.470 s (SD 0.384 s) in RT before contrast medium administration. The contrast-enhanced T1 relaxation time decreased to 0.480 s (SD 0.114 s) in RC and 0.411 s (SD 0.096 s) in RT. There was a significant difference (p > 0.05) between the ?R1 in RC (1.372 × 10?3/s, range 0.526–3.201 × 10?3/s, SD 0.666 × 10?3/s) and RT (1.856 × 10?3/s, range 0.93–3.336 × 10?3/s, SD 0.609 × 10?3/s). The mean r?R1 was 1.49, SD 0.45). The mean MOCART score at follow-up was 62.6 points (range 30–95, SD 15.3). Conclusion: The results of the present study suggest that repair cartilage resulting from AMIC-aided repair of osteochondral lesions of the talus has a significantly lower glycosaminoglycan (GAG) content than normal hyaline cartilage, but can be regarded as having hyaline-like properties

87

CHF prediction for sloping surfaces  

International Nuclear Information System (INIS)

A preliminary analysis of 129 experimental data points obtained in the SULTAN facility (CEA-Grenoble) on CHF in natural circulation, high diameters and sloping surfaces conditions has been performed. A new correlation (DINCE-?) to predict CHF in the above conditions was developed. The correlation is based on a structure identified by the authors during previous studies; it is characterized by very good statistics (72% of prediction within +/- 10%, 89% of predictions within +/- 20%, with an r.m.s error of 12%). Some considerations on possible improvements, with the availability of further data, are presented

88

Kuhse, Singer and slippery slopes.  

Science.gov (United States)

Helga Kuhse and Peter Singer recently examined the view expressed by John Lorber that whereas at times it is permissible to allow severely handicapped infants to die, killing them must never be allowed. In attempting to demonstrate the mistaken nature of Lorber's fear that allowing active infanticide would lead us onto a slippery slope Kuhse and Singer make much use of John Harris's paper in the Journal of Medical Ethics in which he criticised Lorber's views. This paper examines some aspects of the case advanced by Kuhse and Singer and of the earlier paper by Harris. PMID:2972837

Fairbairn, G J

1988-09-01

89

Graphing Equations on the Cartesian Plane: Slope  

Science.gov (United States)

The lesson teaches students about an important characteristic of lines: their slope. Slope can be determined either in graphical or algebraic form. Slope can also be described as positive, negative, zero, or undefined. Students get an explanation of when and how these different types of slope occur. Finally, students learn how slope relates to parallel and perpendicular lines. When two lines are parallel, they have the same slope and when they are perpendicular their slopes are negative reciprocals of one another. Prerequisite knowledge: Students must know how to graph points on the Cartesian plane. They must be familiar with the x- and y- axes on the plane in both the positive and negative directions.

VU Bioengineering RET Program, School of Engineering,

2007-01-01

90

Symposium Proceedings: Slope stability and landslides  

Energy Technology Data Exchange (ETDEWEB)

Speakers at the 13. Annual Meeting of the Vancouver Geotechnical Society emphasized the landslide portion of the official title: 'Slope stability and land slides', if only to draw attention to the fact that although one speaks of slope stability, the focus is on slope failure, why it has occurred, how it has occurred, what it will cost to fix it, and how safe is the finished product . In search of answers to these problems speakers addressed topics such as rock slopes and rock slides on to glaciers, debris flows and avalanches, modeling of seismic behaviour of dams and dykes, submerged slopes and performance monitoring of slopes. State-of-the-art numerical solutions are also reviewed to demonstrate the progress that has been made since slope stability first began to be calculated as a simple relationship between resisting forces versus driving forces. The symposium volume includes the full text of all contributions.

NONE

1999-07-01

91

Error Reduction in Slope Stability Assessment  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Slopes in quarries and open pit mines, as well as all the types of embankments (stockpiles, tailing dams, waste dumps) resulting from mining and mineral processing activities, must be considered as "geotechnical structures". Therefore, the design and implementation of these structures must be conducted with all consideration.The main aim of this chapter is to highlight the basic principles of the slope design process, to review the methods of stability analysis and slope design, as well as th...

Fleurisson, Jean-alain; Cojean, Roger

2014-01-01

92

Slope Estimation from ICESat/GLAS  

Directory of Open Access Journals (Sweden)

Full Text Available We present a novel technique to infer ground slope angle from waveform LiDAR, known as the independent slope method (ISM. The technique is applied to large footprint waveforms (\\(\\sim\\ mean diameter from the Ice, Cloud and Land Elevation Satellite (ICESat Geoscience Laser Altimeter System (GLAS to produce a slope dataset of near-global coverage at \\(0.5^{\\circ} \\times 0.5^{\\circ}\\ resolution. ISM slope estimates are compared against high resolution airborne LiDAR slope measurements for nine sites across three continents. ISM slope estimates compare better with the aircraft data (R\\(^{2}=0.87\\ and RMSE\\(=5.16^{\\circ}\\ than the Shuttle Radar Topography Mission Digital Elevation Model (SRTM DEM inferred slopes (R\\(^{2}=0.71\\ and RMSE\\(=8.69^{\\circ}\\ ISM slope estimates are concurrent with GLAS waveforms and can be used to correct biophysical parameters, such as tree height and biomass. They can also be fused with other DEMs, such as SRTM, to improve slope estimates.

Craig Mahoney

2014-10-01

93

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

94

Internal waves and temperature fronts on slopes  

Directory of Open Access Journals (Sweden)

Full Text Available Time series measurements from an array of temperature miniloggers in a line at constant depth along the sloping boundary of a lake are used to describe the `internal surf zone' where internal waves interact with the sloping boundary. More small positive temperature time derivatives are recorded than negative, but there are more large negative values than positive, giving the overall distribution of temperature time derivatives a small negative skewness. This is consistent with the internal wave dynamics; fronts form during the up-slope phase of the motion, bringing cold water up the slope, and the return flow may become unstable, leading to small advecting billows and weak warm fronts. The data are analysed to detect `events', periods in which the temperature derivatives exceed a set threshold. The speed and distance travelled by `events' are described. The motion along the slope may be a consequence of (a instabilities advected by the flow (b internal waves propagating along-slope or (c internal waves approaching the slope from oblique directions. The propagation of several of the observed 'events' can only be explained by (c, evidence that the internal surf zone has some, but possibly not all, the characteristics of the conventional 'surface wave' surf zone, with waves steepening as they approach the slope at oblique angles.

Key words. Oceanography: general (benthic boundary layers; limnology, Oceanography: physical (internal and inertial waves

S. A. Thorpe

95

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

96

Green Alder Pattern in Relation to Slope-Area Scaling Regimes of a Headwater Basin in the Eastern Italian Alps  

Science.gov (United States)

The landscape of headwater alpine basins is strongly influenced by erosion processes. The scaling relationship between the local slope of a given point on the landscape and its drainage area reveals information about the dominant erosion process over geomorphic time scales. There has been significant research literature which documents how vegetation distribution is coupled with local topography. Understanding the interrelationship between the vegetation, especially between some plant species than others with local topography will help us to better understand how the landscape change due to a specific geomorphic process is related to vegetation change. In this paper a steep Alpine debris flow-landslide dominated headwater catchment with uniform lithology substrata, and vegetation characterized by various grass, shrub, and forest species has been considered. The basin was chosen as study area because it is representative of the lithological and physiographical conditions frequently observed in the Carnia region (Eastern Italian Alps). The work has focused on the analysis of scaling regimes of local slope versus contributing area in relation to each vegetation types with particular attention to the spatial distribution of Alnus viridis, the main shrub species present in the area. Alnus viridis, also known as Green Alder, is an early successional shrub growing up to 4 m that invades screes, landslide scree, avalanche debris on talus slopes, avalanche slide paths and pastures in the subalpine zone of the Alps. It is widespread on moist, north-exposed medium-steep slopes on silicious bedrock at an altitude ranging from 1500 to 2000 m a.s.l.. LiDAR-derived DSM (Digital Surface Model) served as the basis to evaluate the distribution of vegetation canopies. The LiDAR bare-ground elevation points were used for the DTM (Digital Terrain Model) interpolation at the same resolution of the DSM. The results revealed that there is significant relationship between the local slope and drainage area depicting the natural location of Green Alder and other vegetation types. Profound landslide/debris flow topographic signature is detected in areas where Green Alder prevails. Its pioneering ability to colonize the landslide scars and headwater channel hollows, makes it as a key species in the analysis of geomorphic processes at the hillslope/valley transition. The work has broad implications in geomorphology, landscape ecology, landscape evolution with vegetation dynamics for studies in high-altitude extreme-climate Alpine regions.

Tarolli, P.

2007-12-01

97

Factors affecting seismic response of submarine slopes  

Directory of Open Access Journals (Sweden)

Full Text Available The response of submerged slopes on the continental shelf to seismic or storm loading has become an important element in the risk assessment for offshore structures and 'local' tsunami hazards worldwide. The geological profile of these slopes typically includes normally consolidated to lightly overconsolidated soft cohesive soils with layer thickness ranging from a few meters to hundreds of meters. The factor of safety obtained from pseudo-static analyses is not always a useful measure for evaluating the slope response, since values less than one do not necessarily imply slope failure with large movements of the soil mass. This paper addresses the relative importance of different factors affecting the response of submerged slopes during seismic loading. The analyses use a dynamic finite element code which includes a constitutive law describing the anisotropic stress-strain-strength behavior of normally consolidated to lightly overconsolidated clays. The model also incorporates anisotropic hardening to describe the effect of different shear strain and stress histories as well as bounding surface principles to provide realistic descriptions of the accumulation of the plastic strains and excess pore pressure during successive loading cycles. The paper presents results from parametric site response analyses on slope geometry and layering, soil material parameters, and input ground motion characteristics. The predicted maximum shear strains, permanent deformations, displacement time histories and maximum excess pore pressure development provide insight of slope performance during a seismic event.

G. Biscontin

2006-01-01

98

Nocturnal drainage flow on simple slopes  

Science.gov (United States)

Observations of nocturnal slope flow have been made at two sites with quite different topography and vegetation. In both cases, continuous measurements of wind and temperature profiles were made from towers that extended through the depth of the katabatic flow. At the simpler site, which approximates a tilted plane, three towers were located at different distances down the slope to measure the development of slope flow with downslope distance. Slope flow depth, downslope wind speed, and temperature deficit are found to change with downslope distance at rates that are consistent with the predictions of Manins and Sawford's (1979) layer-averaged model of slope flow, while measured entrainment rates are found to be comparable to those predicted by Ellison and Turner's (1959) laboratory experiments. The depth of slope flow is found to be roughly 0.05 times the vertical drop from the top of the slope, a relationship that also follows from combining Manins and Sawford's model and Ellison and Turner's laboratory data. Analysis of the wind spectra and a simple numerical model suggest that the turbulent kinetic energy profiles in slope flow are dependent on the speed and direction of the ambient wind and can differ substantially from those found over flat terrain. At the more complex of the two measurement sites, the occurrence of slope flow was found to correlate well with a dimensionless number 5 that is a function of the ridge-top wind speed and of the strength and depth of the inversion and that is an estimate of the ratio of the buoyancy deficit to the external horizontal pressure gradient.

Horst, T. W.; Doran, J. C.

1986-02-01

99

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

100

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

 
 
 
 
101

Value of magnetic resonance imaging in the mid-term follow-up of osteochondritis dissecans of the femoral condyle and talus  

International Nuclear Information System (INIS)

Purpose: Definition of the prognostic value of clinical and morphological findings in the mid-term follow-up of OCD of the femoral condyle and talus. Demonstration of the consolidation of OCD on MRI depending on different therapies. Materials and Methods: 76 patients were examined before and at an average of 30 months after conservative or surgical therapy using T1 and T2 weighted SE and 3D-FISP sequences and contrast enhanced studies. Six clinical (age, gender, site, duration and severity of symptoms, therapy) and six morphological (size, signal intensity, fragmentation, contrast enhancement, condition of cartilage, staging) data were registered on first MRI and correlated with the degree of consolidation of OCD (partial and complete remission, no change and progression) on control MRI. Results: Patients under 17 years showed partial or complete remissions in 73%, those of 17 years or older in 33%. Conservatively treated patients had a higher remission rate (54%) than those treated with different surgical techniques (drilling 50%, refixation 43%, abrasio 38%). Small OCDs had a higher remission rate than large lesions (63% vs. 33%). OCDs covered with intact cartilage healed better than lesions with chondral defects (61% vs. 26%). Contrast enhancing fragments had a better prognosis than non-enhancing lesions (100% vs. 40%). Conclusions: Prognosis of OCD can be better estimated when size of OCD, condition of cartilage and enhancement of contrast agf cartilage and enhancement of contrast agent is graduated with MRI and patient age is registered. The consequences for therapy planning are great. (orig.)

102

Factorisation of Regge slopes for multiquark hadrons  

International Nuclear Information System (INIS)

Using duality and the factorisation relationships between residues, general rules for expressing the Regge slopes of multi-quark hadrons without string loops in terms of those of the standard three quark baryons and two quark mesons are presented

103

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

104

Statistics of the slope-method estimator  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The slope method has customarily been used and is still used for inversion of atmospheric optical parameters, extinction, and backscatter in homogeneous atmospheres from lidar returns. Our aim is to study the underlying statistics of the old slope method and ultimately to compare its inversion performance with that of the present-day nonlinear least-squares solution (the so-called exponential-curve fitting). The contents are twofold: First, an analytical study is conducted to characterize the...

Rocadenbosch Burillo, Francisco; Comero?n Tejero, Adolfo; Albiol Schnitger, Lorena

1999-01-01

105

Electrokinetic Geotextile Stabilization Of Embankment Slopes  

Directory of Open Access Journals (Sweden)

Full Text Available The choice of repair of slope depends on site conditions and cost. This includes reducing the slope, installing horizontal drains, soil nailing and providing stability by structural methods. All these methods have their limitations and some are very costly. Another alternative is the electrokinetic stabilization of slopes. EKG reinforcement or soil nails not only provide reinforcement, but also increase the shear strength of the soil in which they are placed as well as improving soil-reinforcement bond. The development of EKG materials offers slope stabilisation of embankments and cuttings in fine grained soils, which will significantly increase the factor of safety , address pore pressure changes and also avoids importing earthwork materials or aggregates. By inserting a grid of anodes and a cathode into the ground and applying an electrical potential difference across the slope drives water away, via the cathodes and creates physical changes in the embankment, promoting consolidation of the slope materials. Anodes and cathodes were connected to a DC power circuit and electrified for a calculated period based on water content, strength and electrode spacing. The conductive geotextile used was coir geotextile and it was woven with steel filament in weft direction only. The steel filament made the geotextile conductive. The geotextile used was natural geotextile and it is required after the end of construction of embankment only, till the completion of dissipation of pore pressure.

Mumtaz M

2014-12-01

106

Seasonal slope surface deformation measured with TLS  

Science.gov (United States)

In temperate European climates, soil water removal due to vegetation transpiration peaks in summer and soil rewetting from higher levels of precipitation occurs in winter. In clays of high plasticity, the seasonal cycles of drying and wetting cause the soil to experience a volumetric change, resulting in seasonal shrinking and swelling. For a clay slope exhibiting volume change, such behaviour can lead to excessive deformation and could contribute to strain-softening and progressive slope failure. This can in turn cause traffic disruption and loss of life if roads and railways are founded on or surrounded by such slopes. This paper discusses the driving forces of seasonal surface movement, in particular the role of vegetation, and presents the use of Terrestrial Laser Scanning (TLS) to measure the surface movement of a lightly vegetated London Clay slope near Newbury, UK. Two TLS scans were carried out in early and late summer respectively, representing relative wet and dry conditions of the slope. Continuous field measurements of soil water content in upper layers of the slope were obtained from TDR ThetaProbes already installed at the site. The water content data are used to support the results obtained from TLS by indicating the likely volumetric change in the soil due to loss of water.

Fan, L.; Smethurst, J.; Powrie, W.; Sellaiya, A.

2014-03-01

107

A Brine Extrusion Model for Recurring Slope Lineae  

Science.gov (United States)

Slope streaks and ‘Recurring Slope Lineae’ are examined as a continuum of active surface features best-explained as byproducts from transient extrusions of brines. A brine-seepage model previously established for slope streaks is suggested for RSL.

Mushkin, A.; Gillespie, A. R.; Montgomery, D. R.; Hibbitts, C. A.; Schreiber, B. C.

2014-07-01

108

Valley Evolution and Controls on Present-Day Rock Slope Processes in the Matter and Saas Valleys, Switzerland  

Science.gov (United States)

Landforms in the Matter and Saas Valleys (Kanton Valais, Switzerland) indicate a progressive upstream transition from fluvially dominated to glacially dominated terrains. Large glaciers currently reside in the headwaters of both valleys, and the region was a major ice contributor to the Rhone Valley during the LGM. Characteristic geomorphic indicators linked to morphology, extent of glacial sediments and ice-rock contact surfaces, as well as river and terrace profiles within the two valleys suggest a parallel temporal evolution, despite variations in catchment size, lithology, and glacial input. Slope morphology and fan deposits indicate a concentration of high-energy rock slope activity (such as rock falls, topples, and slides) within a transitional geomorphic domain in the lower 1/3 of both valleys. This transitional domain is defined by a characteristic moderate gradient, linear, river profile. It separates a downstream detachment-limited fluvial domain from a transport-limited domain upstream, where a broad alluvial plain forms a thick infill in the relict glacial valley. Hillslope erosional processes appear considerably less developed and active in these neighboring domains. While the rock slope activity in the transitional domain initially seems to be a clear process response to renewed Holocene fluvial incision in the lower section of the valleys, mapping of glacial landforms indicates only limited incision may have taken place. Activity is concentrated on steep valley walls which extend up to 700m above the current valley floor. These are buttressed by significant talus deposits, which combined with the topography, mean there is likely to be little direct connection from the post-glacial fluvial activity to the erosional hillslope processes. Initial investigations suggest that a combination of repeated glacial erosion and debuttressing, as well as fluvial processes during interglacials may have lead to a significant, consistent differences in post-glacial stress redistribution in each domain. Large deviatoric stresses associated with high relief, and the removal of sedimentary buttresses in the transitional domain, may have induced fracturing of the rock mass through exfoliation and static fatigue, and conditioned rock slopes for ongoing failure.

Leith, K.; Kos, A.; Löw, S.; Moore, J.

2009-04-01

109

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

110

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.

111

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

112

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

113

Modeling historical climate variability and slope stability  

Science.gov (United States)

This study presents scenario models for historical variations of climate and slope stability. A model for historical annual patterns of temperature and rainfall was established on the basis of seasonal proxies. A process-based, spatio-temporal model for groundwater variations and slope stability was developed using the GIS environment of the software PCRaster. We applied the slope stability model to study the effects of the different climate scenarios on slope stability for three different hillslopes in the area around Bonn (Germany). The findings indicate three climatic phases with different annual temperature and precipitation patterns over the historic period. The modeling results show that a climatic scenario representing unstable conditions of a transition from the more humid Little Ice Age to dryer recent climate produces the highest slope instabilities. The intensity of this impact, however, varies with the sensitivity of the geomorphic system, i.e. local landforms and lithology, and cannot be generally related to the stability of a specific hillslope. More unstable areas are not necessarily more sensitive to climatic changes: the location of permeable layers (prone to groundwater rise) in relation to sensitive layers (lower strength) and higher gradients (higher stress) influences the sensitivity of a site with respect to climate changes. The presented method is capable of modeling landscape sensitivity to climate change with respect to groundwater-controlled landslides.

Schmidt, Jochen; Dikau, Richard

2004-06-01

114

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.

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

115

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)

116

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)

117

Risk-based stabilization planning for soil cut slopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Risk-based slope stabilization planning integrates the failure probability and the failure consequence systematically and shows promise for use in the practice. This paper attempts to develop a risk-based methodology for stabilization planning for deteriorating soil cut slopes. First, a framework of risk-based stabilization planning for slopes is proposed. Then the time-dependent reliability of deteriorating slopes is analyzed based on observed performance. Thereafter, the slope failure conse...

Li, D.; Zhang, L.; Zhou, C.; Lu, W.

2009-01-01

118

Measuring acoustic emissions in an avalanche slope  

Science.gov (United States)

Measurements of acoustic emissions are a common technique for monitoring damage and predicting imminent failure of a material. Within natural hazards it has already been used to successfully predict the break-off of a hanging glacier. To explore the applicability of the acoustic emission (AE) technique for avalanche prediction, we installed two acoustic sensors (with 30 kHz and 60 kHz resonance frequency) in an avalanche prone slope at the Mittelgrat in the Parsenn ski area above Davos, Switzerland. The slope is north-east facing, frequently wind loaded, and approximately 35° steep. The AE signals - in particular the event energy and waiting time distributions - were compared with slope stability. The latter was determined by observing avalanche activity. The results of two winter's measurements yielded that the exponent ? of the inverse cumulative distribution of event energy showed a significant drop (from a value of 3.5 to roughly 2.5) at very unstable conditions, i.e. on the three days during our measurement periods when spontaneous avalanches released on our study slope.

Reiweger, Ingrid; Schweizer, Jürg

2014-05-01

119

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.)

120

Stable grounding lines on retrograde slopes  

Science.gov (United States)

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. It is shown that ice-shelf buttressing effects are responsible for restoring stability. Ice flux at the grounding line can, in cases, decrease with increasing thickness. Although not direclty predicted, this, at first sight possibly somewhat counteractive result, is found to be fully consistent with recent theoretical work. 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.

Gudmundsson, G. H.; Krug, J.; Favier, L.; Durand, G.; Gagliardini, O.

2012-12-01

 
 
 
 
121

T1 Slope and Degenerative Cervical Spondylolisthesis.  

Science.gov (United States)

Study Design. Retrospective analysisObjective. The main objectives of this study were to analyze and compare cervical sagittal parameters, including the T1slope, in a population of 45 patients with degenerative cervical spondylolisthesis (DCS) and to compare these patients with a control group of asymptomatic population.Summary of Background Data. Sagittal balance in the cervical spine is as important as the pelvic incidence (PI) and is related to the concept of T1 slope. When compared with degenerative lumbar spondylolisthesis(DLS), there are few studies evaluating DCS, and characteristic changes of the cervical sagittal parameters (including T1sope) in DCS patient are not well studied.Methods. We identified 45 patients with DCS (5.8%) from a database of 767 patients, using cervical X-ray in a standing position. All had X-ray and CT scan at the same time. Cervical sagittal parameters were analyzed on CT scan in a standardized supine position.The following cervical sagittal parameters were measured: T1slope, neck tilt (NT), thoracic inlet angle (TIA) and cervical lordosis (C2-7 angle). The DCS group was compared with a control group of 45 asymptomatic adults, age and sex matched to DCS group, who were studied in a recently published study.Results. Of our initial group of 767 patients, 45 with anterolisthesis (5.8%) were included for this study. The T1slope was significantly greater for DCS (26.06 ± 7.3 degrees) compared with the control group (22.32 ± 7.0 degrees). No significant difference of the NT, TIA and C2-7 angle was seen between the DSC group and the control group. Therefore, the T1slope of the DSC group was significantly greater than that of the control group (P <0.005).Conclusion. DCS group were characterized by a greater T1slope than the control group; therefore, we suggest that a high T1slope may be a predisposing factor in developing DCS. PMID:25423304

Jun, Hyo Sub; Kim, Ji Hee; Ahn, Jun Hyong; Chang, In Bok; Song, Joon Ho; Kim, Tae Hwan; Park, Moon Soo; Kim, Yong Chan; Kim, Seok Woo; Oh, Jae Keun

2014-11-21

122

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

123

Clustering Moving Objects Using Segments Slopes  

Directory of Open Access Journals (Sweden)

Full Text Available Given a set of moving object trajectories, we show how to cluster them using k-meansclustering approach. Our proposed clustering algorithm is competitive with the k-means clusteringbecause it specifies the value of “k” based on the segment’s slope of the moving object trajectories. Theadvantage of this approach is that it overcomes the known drawbacks of the k-means algorithm, namely,the dependence on the number of clusters (k, and the dependence on the initial choice of the clusters’centroids, and it uses segment’s slope as a heuristic to determine the different number of clusters for thek-means algorithm. In addition, we use the standard quality measure (silhouette coefficient in order tomeasure the efficiency of our proposed approach. Finally, we present experimental results on both realand synthetic data that show the performance and accuracy of our proposed technique.

Mohamed E. El-Sharkawi

2011-03-01

124

Ski slope vegetation in central Honshu, Japan  

Science.gov (United States)

To determine the status of the vegetation of ski slopes in northeastern-central Honshu, Japan, 94 plots (2×2 m) were set up on five ski areas (101-520 m elevation) which were established between 1945 and 1985 by forest clear-cutting, land modification, and seeding. Six vegetation types were recognized: five grasslands dominated by Digitaria adscendens, Miscanthus sinensis, Zoysia japonica, Festuca rubra, and Pteridium aquilinum var. latiusculum, respectively, and bare areas of very low to no vegetation cover. Of the dominant species, F. rubra is the only introduced species; it does not, however, appear to persist. After the introduced grassland declines M. sinensis or annual grasslands develop. Native plants, especially woody species, can establish in M. sinensis grassland but do not establish in the other grasslands. It is concluded that the introduction of exotic species is inappropriate to maintain ski slope vegetation, and the development of M. sinensis grassland is desirable to promote natural revegetation.

Tsuyuzaki, Shiro

1995-09-01

125

The Salpeter Slope of the IMF Explained  

CERN Document Server

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 instrinsic 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 S

2012-01-01

126

In-Place Randomized Slope Selection  

DEFF Research Database (Denmark)

Slope selection is a well-known algorithmic tool used in the context of computing robust estimators for fitting a line to a collection P of n points in the plane. We demonstrate that it is possible to perform slope selection in expected O(nlogn) time using only constant extra space in addition to the space needed for representing the input. Our solution is based upon a space-efficient variant of Matoušek’s randomized interpolation search, and we believe that the techniques developed in this paper will prove helpful in the design of space-efficient randomized algorithms using samples. To underline this, we also sketch how to compute the repeated median line estimator in an in-place setting.

Blunck, Henrik; Vahrenhold, Jan

2006-01-01

127

The Alaska North Slope spill analysis  

International Nuclear Information System (INIS)

This paper reports Alaska North Slope crude oil spills, provides information to help operators identify risks and presents recommendations for future risk reduction and mitigation measures that may reduce the frequency and severity of future spills from piping infrastructure integrity loss. The North Slope spills analysis project was conducted during 2010 by compiling available spill data, and analyzing the cause of past spills in wells and associated piping, flowlines, process centers with their associated piping and above ground storage tanks, and crude oil transmission pipelines. An expert panel, established to provide independent review of this analysis and the presented data, identified seven recommendations on measures, programs, and practices to monitor and address common causes of failures while considering information provided from regulators and operators. These recommendations must be evaluated by the State of Alaska which will consider implementation options to move forward. Based on the study observations, future analyses may show changes to some of the observed trends.

128

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

129

Transhumanism, medical technology and slippery slopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this article, transhumanism is considered to be a quasi?medical ideology that seeks to promote a variety of therapeutic and human?enhancing aims. Moderate conceptions are distinguished from strong conceptions of transhumanism and the strong conceptions were found to be more problematic than the moderate ones. A particular critique of Boström's defence of transhumanism is presented. Various forms of slippery slope arguments that may be used for and against transhumanism are discussed a...

Mcnamee, M. J.; Edwards, S. D.

2006-01-01

130

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

131

Biostabilization of Mandaman dump slope, India  

Energy Technology Data Exchange (ETDEWEB)

An integrated study of the biological stabilization of a coal-mine overburden dump slope has been carried out at Mandaman, 35 km from Dhanbad in eastern India. Native grasses bamboo (Dendrocalmus strictus) and kashi (Saccharum spontaneum) are important species that can stabilize the dump slopes. The grasses have good soil binding capacity and help to control soil erosion and improve dump stability. Field observation of their growth performance has indicated that the mean grass height and root depth are 232 (+/- 74) cm and 46 (+/-5) cm, respectively, after three years and the below-ground root biomass is 474 (+/- 69) g m{sup -2}. The mechanical and hydrogeological actions of the grass roots have improved the shear strength properties of the dump material. Numerical modelling has shown that the roots of these grasses increase the factor of safety of the dump slope from 1.2 to 1.4 and thus play a substantial role in the maintenance of long-term stability.

Chaulya, S.K.; Singh, R.S.; Chakraborty, M.K.; Tewary, B.K.; Srivastava, B.K. [Central Mining Research Institute, Dhanbad (India)

2001-08-01

132

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

133

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

134

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

135

Overview of gas hydrates in submarine slopes  

Energy Technology Data Exchange (ETDEWEB)

Gas hydrates are solid crystalline compounds consisting of hydrogen-bonded water molecules that form a rigid crystal lattice stabilized by encaged gas molecules. Their stability is confined to low-temperature, high-pressure regimes such as those found in permafrost regions and under the seafloor on continental slopes. In-situ natural gas hydrate deposits are typically located in marine sediments at temperatures of 5 to 10 degrees C. The critical factors influencing hydrate formation and stability are pressure, temperature, gas composition, volume of bulk free water, salinity, gas availability, sediment type, and the presence of catalysts or inhibitors. Circumstantial evidence suggests that large submarine landslides along the continental margins can be triggered by the weakening of hydrate bearing sediments. Hydrate dissociation results in loss of solid material, production of free gas, and increased fluid pressures, all which have the effect of reducing sediment strength. These underwater landslides have the potential to destroy offshore equipment, jeopardize safety of personnel, and generate tsunamis. This paper presented recent results and advances on the intersection of gas hydrates and submarine slope stability, with particular reference to the role of gas hydrates in triggering or propagating submarine mass movements. It was concluded that the cause of slope failures is not fully understood because of the complexities of gas hydrates and their interactions with the host sediment, combined with the high cost of laboratory and field investigations. 35 refs., 2 figs.

Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

2009-07-01

136

Stability of the slopes around nuclear power plants in earthquake  

International Nuclear Information System (INIS)

The evaluation of the stability of the slopes around the buildings of nuclear power plants is important especially with respect to earthquakes. In this connection, the behavior of a slope up to its destruction and the phenomena of the destruction have been examined in the case of an earthquake by both experiment and numerical analysis. The purpose is to obtain the data for the establishment of a method for evaluating the seismic stability of a slope and of the slope design standards. The following results are described: the behavior of a slope and its destruction characteristics in the slope destruction experiment simulating the seismic coefficient method; the vibration of a slope and its destruction characteristics in vibration destruction experiment; the validity of the method of numerical simulation analysis and of stability evaluation for the slope destruction and the vibration destruction experiments, and quantitative destruction mechanism; the comparison of the various stability evaluation methods and the evaluation of seismic forces. (Mori, K.)

137

Analysis methods on stability of tall and bedding creep slope  

Energy Technology Data Exchange (ETDEWEB)

Based on the model of slope engineering geology, the creep and its failure mechanism of a tall and inclined bedded slope are analyzed in this paper. The creep laws of weak intercalations are also discussed. The analysis at the Haizhou open pit coal mine, China of the stability of the creep slope and the time forecasting of slope sliding were conducted through numerical simulations using Finite Element Method (FEM) and Distinct Element Method (DEM). 5 refs., 6 figs.

Rui, Y.; Jiang, Z.; Liu, J. [Central Coal Mining Research Institute, Fushun (China)

1995-12-01

138

Diverse soft X-ray slopes of QSOS  

International Nuclear Information System (INIS)

Einstein spectra are presented for 30 QSOs which indicate a large diversity in their soft X-ray slopes, unlike the uniform slopes found for AGN with higher X-ray energies. The slope is related to radio properties, X-ray luminosity, or possibly redshift, but these possibilities cannot be definitively distinguished. 7 references

139

The Jones polynomial and boundary slopes of alternating knots  

CERN Document Server

We show for an alternating knot the minimal integral boundary slope is given by the signature plus twice the minimum degree of the Jones polynomial and the maximal integral boundary slope is given by the signature plus twice the maximum degree of the Jones polynomial. For alternating Montesinos knots, these are the minimal and maximal boundary slopes.

Curtis, Cynthia L

2009-01-01

140

Transhumanism, medical technology and slippery slopes.  

Science.gov (United States)

In this article, transhumanism is considered to be a quasi-medical ideology that seeks to promote a variety of therapeutic and human-enhancing aims. Moderate conceptions are distinguished from strong conceptions of transhumanism and the strong conceptions were found to be more problematic than the moderate ones. A particular critique of Boström's defence of transhumanism is presented. Various forms of slippery slope arguments that may be used for and against transhumanism are discussed and one particular criticism, moral arbitrariness, that undermines both weak and strong transhumanism is highlighted. PMID:16943331

McNamee, M J; Edwards, S D

2006-09-01

 
 
 
 
141

Slope stability of moraines, Cordillera Blanca, Peru  

Science.gov (United States)

Landslides originating from inner slopes of moraine dams are often capable of producing glacial lakes outburst floods (GLOFs). Therefore assessing stability conditions of the moraines is important for predicting this potentially damaging phenomenon. Characteristics of the basic mechanical properties of the material and geophysical investigations were applied to collect necessary information for slope stability assessment of the Palcacocha Lake moraine dam, Peru. The lake is situated in the Cordillera Blanca Mts. at the altitude of about 4,500m asl and produced catastrophic GLOF in 1941. Another minor flood originated in 2003 due to landslide impact into the lake. Detailed investigations of this landslide site included geomorphological mapping, geophysical investigations and characterization of basic mechanical properties of the forming material. Geomorphological mapping identified dormant landslide with scarp up to 2m high which developed on the edge of the inner moraine slope. It is conditioned by set of parallel extension trenches which also affected the origin of 2003 landslide. Within its scarp area, significant water bearing layer was noticed around 10 m bellow the moraine surface. Three profiles were investigated using electric resistivity tomography performed on 4poing light instrument with 24 electrodes and with spacing ranging from 1 to 4m. Results helped to verify geometry of the main shear plane of the mapped landslide as well as the spacing and depth of extension trenches. Significant heterogeneity in the moraine resistivity characteristics was found. The high resistivity regions are explained by rock block accumulation whereas the low resistivity may represent wet layers within the moraine body. Grain size distribution of 33 disturbed soil samples originating from moraine material within the Cordillera Blanca Mts., Peru were determined and classified according to the UCSC classification system. The samples were taken from moraine dams and slopes covered by moraine material. 11 samples were also tested for the angle of repose. These results were compared with literature data relating grains size distribution of similar soil types with measured shear strength characteristics to assess peak shear strength ?max of the analyzed samples. Rough estimates of these values indicate that the moraine material gains 35°-38o. These estimates are verified by measured angle of repose. Results of the grain size distribution were also used to estimate average hydraulic conductivity applying Hazen formula. This estimates show that investigated moraine material range from 6x10-6 to 3x10-4 m/s.

Klimes, J.; Novotny, J.

2012-12-01

142

alpha-sloped Generalized Heegaard splittings of 3-manifolds  

CERN Document Server

We generalize the definition of thin position of Scharlemann and Thompson for compact orientable 3-manifolds with torus boundary components and introduce $\\alpha$-sloped generalized Heegaard splittings. We examine its relationship to generalized Heegaard splittings of manifolds resulting from Dehn filling. We compare alpha-sloped thin position of 3-manifolds to other types of thin position for knots and 3-manifolds and discuss how this kind of decomposition gives an organic picture of M and allows the structure of the manifold to dictate the most natural slope(s) on the boundary. Additionally, we provide illustrative examples and questions motivating the study of alpha-sloped thin position.

Campisi, Marion Moore

2011-01-01

143

Water budgets of martian recurring slope lineae  

Science.gov (United States)

Flowing water, possibly brine, has been suggested to cause seasonally reappearing, incrementally growing, dark streaks on steep, warm slopes on Mars. We modeled these Recurring Slope Lineae (RSL) as isothermal water flows in thin surficial layers driven by gravity and capillary suction, with input from sources in the headwall and loss to evaporation. The principal observables are flow duration and length. At 40% porosity, we find that flow thicknesses reaching saturation can be just 50 mm or so and freshwater RSL seasonally require 2-10 m3 of H2O per m of source headwall. Modeled water budgets are larger for brines because they are active for a longer part of each day, but this could be partly offset by lower evaporation rates. Most of the discharged water is lost to evaporation even while RSL are actively lengthening. The derived water volumes, while small, exceed those that can be supplied by annual melting of near-surface ice (0.2-2 m3/m for a 200-mm melt depth over 1-10 m height). RSL either tap a liquid reservoir startlingly close to the surface, or the actual water budget is several times smaller. The latter is possible if water never fully saturates RSL along their length. Instead, they would advance like raindrops on a window, as intermittent slugs of water that overrun prior parts of the flow at residual saturation. Annual recharge by vapor cold trapping might then be supplied from the atmosphere or subsurface.

Grimm, Robert E.; Harrison, Keith P.; Stillman, David E.

2014-05-01

144

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.

2010-12-01

145

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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 técnica 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.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 were 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

2010-12-01

146

Morphology and origins of sedimentary structures on submarine slopes.  

Science.gov (United States)

Submarine slopes in deep water, such as continental slopes, are often indented by valleys or channels and made uneven by ridges or levees. The origins of many of these features are unknown or disputed. Morphologically, however, there is often great similarity between forms on deep slopes and forms on shallow slopes or on land. Structurally the slopes in deep water are less well explored, but several observations reveal features, such as lamination and crossbedding, that are known from shallow water also. Measurements of current indicate that periodically the movement of water near the bottom is fast enough to move particles of sediment from time to time. Morphology, fine structure, and currents suggest that internal waves and associated currents, as well as gravity, may control the shape of deep submarine slopes analogously to the shaping by surface waves of slopes in shallow water. PMID:17756512

Hulsemann, J

1968-07-01

147

Design principles for optimizing an established survey slope monitoring system  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english When slope angles are designed during open pit optimization, there is a risk factor applied in steepening the slopes. The steepening of slope angles has implications for the safety and economics of the mining operation. The steeper the slope angles, the greater the probability of slope failure. Alth [...] ough a slope failure will result in added costs, the challenge is to compile an accurate cost-benefit exercise optimizing the economic benefits of the project without exposing mine workers and equipment to unacceptable risk of rockfalls. A balance between the safety of the operation and the economics of the investment is therefore required. The ideal situation is to have a slope monitoring system that will predict slope failure by detecting any ground movement before the actual failure occurs. This early warning will allow the risk factor to be applied with a high degree of confidence, knowing that the risk will be adequately mitigated. The objective of this paper is to provide guidelines on how to design an optimal survey slope monitoring system. It is the authors' view that for a survey monitoring system to yield desirable results, it should adhere to survey principles such as working from the whole to part and consistently cross-checking. The case study used is Jwaneng Mine, and the design strategy outlined can be used as a guideline for developing a new slope monitoring system or to optimize an existing one.

N, Mphathiwa; F.T, Cawood.

2014-06-01

148

Erosion dynamics following localized permafrost slope disturbances  

Science.gov (United States)

disturbances are key sources of sediment, and the impact and recovery of disturbance on downslope erosion is poorly understood. We measured the erosional response of varying extents of slope disturbance in small permafrost catchments for 5 years following disturbance by active layer detachments. Initial erosion rates increased with the size of disturbance, but subsequent fluxes depended on specific morphological evolution of disturbances. Varying degrees of (i) channel density within the disturbances, (ii) downstream channel connectivity, and (iii) geomorphic evolution of disturbances lead to significant differences in catchment response to disturbance. Our results indicate that new equilibrium states of sediment erosion are achieved within the most disturbed and channelized catchments and contribute to greater heterogeneity of erosion on the landscape.

Lamoureux, Scott F.; Lafrenière, Melissa J.; Favaro, Elena A.

2014-08-01

149

Model tests of geosynthetic reinforced slopes in a geotechnical centrifuge  

International Nuclear Information System (INIS)

Geosynthetic-reinforced slopes and walls became very popular in recent years because of their financial, technical, and ecological advantages. Centrifuge modelling is a powerful tool for physical modelling of reinforced slopes and offers the advantage to observe the failure mechanisms of the slopes. In order to replicate the gravity induced stresses of a prototype structure in a geometrically 1/N reduced model, it is necessary to test the model in a gravitational field N times larger than that of the prototype structure. In this dissertation, geotextile-reinforced slope models were tested in a geotechnical centrifuge to identify the possible failure mechanisms. Slope models were tested by varying slope inclination, tensile strengths of the geotextiles, and overlapping lengths. Photographs of the geotextile reinforced slope models in flight were taken with a digital camera and the soil deformations of geotextile reinforced slopes were evaluated with Particle Image Velocimetry (PIV). The experimental results showed that failure of the centrifuge models initiated at midheight of the slope, and occurred due to geotextile breakage instead of pullout. The location of the shear surface is independent of the tensile strength of the geotextile; it is dependent on the shear strength of the soil. It is logical to see that the required acceleration of the centrifuge at slope failure was decreased with increasing slope inclination. An important contribution to the stability of thertant contribution to the stability of the slope models was provided by the overlapping of the geotextile layers. It has a secondary reinforcement effect when it was prolonged and passed through the shear surface. Moreover, the location of the shear surface observed with PIV analysis exactly matches the tears of the retrieved geotextiles measured carefully after the centrifuge testing. It is concluded that PIV is an efficient tool to instrument the slope failures in a geotechnical centrifuge.(author)

150

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

151

Understanding snow deposition on mountain slopes  

Science.gov (United States)

Snow water storage in the mountains is vital for summer water supply in many areas of the world and snow deposition determines the avalanche danger. While mountain snow covers have been investigated for many decades, we only now have the technology to measure high resolution snow distribution in steep terrain. High resolution airborne and terrestrial LASER scanner data are used in this contribution to assess snow distributions in two high Alpine catchments. For the first time, multiple measurements during the accumulation phase are analyzed. The measurements show that sub-areas in the investigation have persistent inter- and intra-annual accumulation patterns, which differ from area to area. These observations motivate the use of simple parameters of terrain exposure to predict accumulation patterns. The Winstral parameter showed a locally high predictive skill, provided a good knowledge on local wind direction is available, which can be found from measurements or simple parameterizations. For a more detailed investigation of physical processes, three-dimensional flow fields are needed. Detailed wind fields are created with an atmospheric numerical model (ARPS) and used to drive the physical process description of snow deposition in the numerical model Alpine3D. The numerical simulations with a grid resolution of 5 m show that snow redistribution (in particular saltation) lead to the formation of inhomogeneous snow distributions in a particular slope in the form of drifts, while homogeneous deposition of snow is achieved through preferential deposition in other slopes. These results help to understand that typical assumptions on altitudinal precipitation gradients appear to poorly represent real snow distribution.

Mott, Rebecca; Grünewald, Thomas; Schirmer, Michael; Wirz, Vanessa; Lehning, Michael

2010-05-01

152

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

153

On barotropic and baroclinic tides over an arbitrary sloping topography  

Directory of Open Access Journals (Sweden)

Full Text Available Some theoretical concepts about the frictionless dynamics of propagation of the barotropic tide over two-dimensional continental slopes of arbitrary shape are developed. A numerical procedure which generalizes the exact solution obtained over a rectilinear sloping topography is given. This technique can be applied to compute the harmonic components of the barotropic tide everywhere over sloping bottom contours of any shape. It permits in particular the avoidance of discontinuities at the boundaries of rectilinear-continental-slope profiles. The barotropic tidal results are used afterwards to calculate the barotropic forcing for the generation of internal tides. Numerical experiments are performed to study the interaction between the tide and some typical sloping topographies. A three-layered model is used for this purpose. Results are compared with those previously obtained over a rectilinear continental slope.

J. Y. Le Tareau

154

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

155

Investigation of Wetting Pattern Dimensions on Sloping Lands  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Mohammadi, A.; Biglouei, M. H.; Khaledian, M. R.; Moridnejad, A. R.; Rajabi, J.

2014-01-01

156

Research on the Slope Protection Mechanism of Roots  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 tensio...

Juan Wan; Henglin Xiao; Jun He; Lihua Li

2013-01-01

157

Study on slope engineering in China open pit coal mine  

Energy Technology Data Exchange (ETDEWEB)

This paper briefly introduces the main content of a study on slope engineering in Chinese open pit coal mines. This paper also discusses the applications of open pit mining and surrounding rock stability, water pressure control in slope, controlled mining technology, slope monitoring and measurement, and other R & D results in obtaining optimum mining conditions, increasing mine economic benefits and mine safety and production with certain mine operation cases. 2 refs., 8 figs.

Ma Xinming; Hou Qiyuan; Rui Yongqing [Central Coal Mining Research Institute (China). Fushun Branch

1994-12-31

158

Development of an Intra-Slope Basin Offshore Southwestern Taiwan  

Science.gov (United States)

Distribution and architecture of intra-slope basins across continental slope vary as a consequence of accommodation forming, sediment dispersal rates, canyon cutting, sediment filling and different sediment transporting mechanisms. The area offshore Southwestern Taiwan is generally recognized as having active tectonics and high sediment deposition rate. In the Gaoping Slope, intra-slope basins are formed by the development of faults, diapiric intrusions and folds. Parts of sediments discharged from the Taiwan mountain belt have been trapped in these basins in the Gaoping Shelf and Gaoping Slope. The rest of those sediments have been transported to deep sea area through submarine canyons which also passed some of basins in the slope area. This complex system of faults, diapirs, folds, basins, canyons, and sediment deposits also readjust morphology of the Gaoping Slope region. This study examines the development of an intra-slope basin in the upper-slope domain of the Gaoping Slope through seismic facies analysis. 2D seismic reflection profiles as well as a 3D seismic volume are used to reveal the complex development of this slope basin. 6 stratigraphic units have been identified in the basin, and 8 diapiric ridges and diapirs are observed either bounded this basin or developed within the basin. The growth relationships between different stratigraphic units and diapirs provide us relative time constraints on the sedimentation and structural developments of this basin. Mass transport deposits (MTDs) are frequently observed within the basin strata, suggesting unstable deposition environment. The source of the orogenic sediments deposited in the basin mostly came from north, but the most recent sediments are brought in from the Fangliao Canyon which lies to the east of the basin. From the detail 3D seismic images, we propose a development model of this slope basin.

Liu, C.-S.; Chang, Y.-T.; Hsu, H.-H.; Chen, S.-C.; Chung, S.-H.

2012-04-01

159

Interactions between down-slope and along-slope processes on the South China Sea Slope off southwestern Taiwan: Processes, products, and depositional models  

Science.gov (United States)

A high-quality 2-D database, that includes the multi-beam bathymetry, high-resolution seismic profiles, piston cores, AMS 14C dating, micropaleontological data, and the concentrations of rear earth elements, was used to investigate: (1) the recent depositional processes and associated deposits on the South China Sea Slope off southwestern Taiwan; (2) the spatial distribution and temporal evolution of the surface and near-surface deposits; (3) the interactions between down-slope turbidity currents and along-slope bottom currents in the study area. High-resolution seismic profiles and piston core analysis suggest nine facies, which can be further grouped into four major depositional systems: the shelf-edge deltaic depositional system, turbidite depositional system, mixed contourite and turbidite system, and contourite depositional system. The surface and near-surface deposits vary both spatially and temporally. Spatially, the shelf-edge deltas are the predominate depositional features on the flat-lying shelf. High-energy gravity flows and associated erosional features, in contract, are common on the steep and narrow upper slope. Seaward, the gentle middle slope is characterized by intense gravity flows and their resultant turbidite depositional system. The interactions between down- and along-slope processes generated mixed contourite and turbidite system are the most representative characteristics on the lower slope. Along-slope processes associated contourite depositional system, in contract, are the dominant deposits on continental rise. Temporally, the mixed contourite and turbidite system as shown the sandy and coarser grained units TS01-2 and TS02-2 are well developed during the glaciations. The integrated data shows that the spatial distribution and temporal evolution of the surface and near-surface deposits were likely controlled by a series of factors, including slope gradient, shelf break and slope-break belts, lee effect, the glacial/interglacial cycles, sea-level fluctuation, and the climate change. In addition, rapid uplift and denudation of the Taiwan Island due to arc-continent collision most probably led to high sediments supply to and sedimentation rates in the study area. Recent depositional processes and interactions between down- and along-slope processes vary both spatially and temporally. Spatially, high-energy gravity flows most probably dominate over the relatively weak bottom currents, leading to the intense erosion and erosional features on the steep and narrow upper slope. On the gentle middle slope, the gravity flows may lose part of their energy but still vigorous which most likely mask the relatively weak bottom currents, resulting in the well development of turbidite depositional system. On the lower slope, both turbidity currents and bottom currents are active, the interactions between down- and along-slope processes are typical and predominant, resulting in a mixed contourite and turbidite system. Further basinward onto the continental rise, turbidity currents wane to minimal and along-slope processes are predominant, leading to the wide occurrence of contourite depositional system in this region. Temporally, interactions between down- and along-slope processes are strong during glaciations, and wake during interglacial periods. As a result, the mixed contourite and turbiditie system were widely developed during the glaciations. The proposed depositional models are markedly different in which interactions between down- and along-slope processes are variable in space and time. The results from this study also provide the further evidence for the intrusion of the Northern Pacific Deep Water into the South China Sea and suggest that this intrusion has probably existed and been capable of affecting sedimentation in South China Sea at least since Quaternary.

Gong, Ch. L.; Wang, Y. M.; Li, W. G.; Peng, X. Ch

2012-04-01

160

STUDI PERKUATAN LERENG DENGAN SOFTWARE GEO SLOPE PADA TANAH LEMPUNG  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract: The slope is a topography condition which has been seen in many civil construction works. The slope can occur naturally or be made by people for several purposes. The slope stability analysis has very important roles at civil construction plan. Where the condition of existing land were not always agree with our plan, for example: if the slope is too steep so it requires to be cut then need to do cutting works, or the other condition we need to do requiring hoard and so on, so that n...

Subri, Subriadi

2013-01-01

 
 
 
 
161

Land use as it relates to land slope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The goal of this project is to analyze the relationship between the slope of land and agricultural land use. The output was analyzed to determine a threshold point at which agriculture practices drop off in relation to higher slope values. Slope of the land is important to agricultural practices because it impacts drainage and net crop primary production. Agricultural land was extracted from the 2001 National Land Cover Dataset using reclassification tools in ArcGIS 9.3. The slope of the c...

Plourde, James D.; Pijanowski, Bryan C.

2010-01-01

162

Boundary slopes of 2-bridge links determine the crossing number  

CERN Document Server

A diagonal surface in a link exterior M is a properly embedded, incompressible, boundary incompressible surface which furthermore has the same number of boundary components and same slope on each component of the boundary of M. We derive a formula for the boundary slope of a diagonal surface in the exterior of a 2-bridge link which is analogous to the formula for the boundary slope of a 2-bridge knot found by Hatcher and Thurston. Using this formula we show that the diameter of a 2-bridge link, that is, the difference between the smallest and largest finite slopes of diagonal surfaces, is equal to the crossing number.

Hoste, J E; Hoste, Jim E.; Shanahan, Patrick D.

2006-01-01

163

Degenerating slopes with respect to Heegaard distance  

CERN Document Server

We prove a result about Heegaard distance, analogous to the generalization of Thurston's hyperbolic Dehn surgery theorem, namely we prove: If $M=H_{+}\\cup_{S} H_{-}$ is a genus $g$ Heegaard splitting with Heegaard distance $n\\geq \\kappa+2$, and $c_{1}$, $c_{2}$ are two slopes in the same component of $\\partial_{-}H_{-}$, with the natural Heegaard splitting $M^{i}=H_{+}\\cup_{S} (H_{-}\\cup_{c_{i}} 2-handle)$ has distance less than $n$, then the distance of $c_{1}$ and $c_{2}$ in the curve complex is at most $3\\mathfrak{M}+2$, where $\\kappa$ and $\\mathfrak{M}$ are constants due to Masur-Minsky. And we also prove that fixed a homeomorphism from $\\partial_{-}H_{-}$ to the boundaries of a set of handlebodies $\\mathscr{H}$, then for generic Pseudo-Anosov map $f:\\partial \\mathscr{H} \\to \\partial \\mathscr{H}$, all sufficiently large power of it resulting in a distance $n$ Heegaard splitting. The proofs rely heavily on Masur-Minsky's theory of curve complex.

Ma, Jiming

2009-01-01

164

Seismic Slope Stabilty Analysis: Gurpinar (Istanbul) As A Case History  

Science.gov (United States)

Slope failures triggered by the earthquakes are one of the most important soil problems. In this study, dynamic (earthquake) slope stability analysis was carried out in Gurp?nar area. For this aim, in situ tests (SPT) were carried out and laboratory samples were obtained from 6 boreholes (their max. dept 50.0m) to determine soil classification and strength characteristics. Moreover, geophysical studies (seismic refraction and MASW) were also carried out in the area to estimate the structure and strength characteristics of the slope to 50.0 m. All of data, obtained in field and laboratory, was used to construct the mechanical and structural (geometrical) behavior of the slope. To solve slope stability problem, tree soil slope model was considered for the area. In dynamic state, to estimate the earthquake acceleration seismic hazard analysis was carried out in the region. In the end of the analysis, while there is not any problem in static condition/loads, some slope stability problems was appeared with increasing earthquake acceleration. A geotechnical slope improvement project was proposed for the study area.

Ozcep, Ferhat; Erol, Engin; Saracoglu, Fatih; Haliloglu, Mustafa

2010-05-01

165

RMS slope of exponentially correlated surface roughness for radar applications  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

166

Application of the Finite Element Method to Slope Stability  

Science.gov (United States)

This document outlines the capabilities of the finite element method in the analysis of slope stability problems. A description of the constitutive laws of material behavior such as the Mohr-Coulomb failure criterion, and material properties input parameters, required to adequately model slope failure is given as well.

2008-09-23

167

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

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

DESIGN INFORMATION REPORT: PROTECTION OF WASTEWATER LAGOON INTERIOR SLOPES  

Science.gov (United States)

A problem common to many wastewater treatment and storage lagoons is erosion of the interior slopes. Erosion may be caused by surface runoff and wind-induced wave action. The soils that compose the steep interior slopes of lagoons are especially susceptible to erosion and slumpin...

170

Recurring slope lineae in equatorial regions of Mars  

Science.gov (United States)

The presence of liquid water is a requirement of habitability on a planet. Possible indicators of liquid surface water on Mars include intermittent flow-like features observed on sloping terrains. These recurring slope lineae are narrow, dark markings on steep slopes that appear and incrementally lengthen during warm seasons on low-albedo surfaces. The lineae fade in cooler seasons and recur over multiple Mars years. Recurring slope lineae were initially reported to appear and lengthen at mid-latitudes in the late southern spring and summer and are more common on equator-facing slopes where and when the peak surface temperatures are higher. Here we report extensive activity of recurring slope lineae in equatorial regions of Mars, particularly in the deep canyons of Valles Marineris, from analysis of data acquired by the Mars Reconnaissance Orbiter. We observe the lineae to be most active in seasons when the slopes often face the sun. Expected peak temperatures suggest that activity may not depend solely on temperature. Although the origin of the recurring slope lineae remains an open question, our observations are consistent with intermittent flow of briny water. Such an origin suggests surprisingly abundant liquid water in some near-surface equatorial regions of Mars.

McEwen, Alfred S.; Dundas, Colin M.; Mattson, Sarah S.; Toigo, Anthony D.; Ojha, Lujendra; Wray, James J.; Chojnacki, Matthew; Byrne, Shane; Murchie, Scott L.; Thomas, Nicolas

2014-01-01

171

Wave run-up on permeable fixed reveted slopes  

Directory of Open Access Journals (Sweden)

Full Text Available A numerical model of surface wave movement and water filtration in saturated-unsaturated porous medium has been developed. The model can be used to define the parameters of the wave run-up on the slope protected with a permeable fixed layer. The model is applied to determine positions of the free wave surface at the different times, including such parameters as the height of wave run-up and wave run-down on the slope. In addition, both flow velocity field in the upper protected layer and moisture distribution in the soil body of the slope were defined. The model is verified with the results of the published large-scale tests that have been conducted at Technical University Braunschweig in the wave flume with the slopes protected according to Elastocoast technology. The numerical model can be applied to calculate the run-up of extreme waves on protected engineering and beach slopes in natural conditions.

I.G. Kantardgi

2014-10-01

172

Spectral Slope and Kolmogorov Constant of MHD Turbulence  

International Nuclear Information System (INIS)

The spectral slope of strong MHD turbulence has recently been a matter of controversy. While the Goldreich-Sridhar model predicts a -5/3 slope, shallower slopes have been observed in numerics. We argue that earlier numerics were affected by driving due to a diffuse locality of energy transfer. Our highest-resolution simulation (30722x1024) exhibited the asymptotic -5/3 scaling. We also discover that the dynamic alignment, proposed in models with -3/2 slope, saturates and cannot modify the asymptotic, high Reynolds number slope. From the observed -5/3 scaling we measure the Kolmogorov constant CKA=3.27±0.07 for Alfvenic turbulence and CK=4.2±0.2 for full MHD turbulence, which is higher than the hydrodynamic value of 1.64. This larger CK indicates inefficient energy transfer in MHD turbulence, which is in agreement with diffuse locality.

173

The slope preserving id positive modified quadratic shepard interpolant  

International Nuclear Information System (INIS)

We preserved positivity through a control over the minimum point to get a positive cubic Hermite (see Asim and Brodlie (3)) D. We think we are first to introduce this technique. Subsequently we extended the idea to preserve positivity by obtaining a control over the extremum point of the basis functions of the Modified Quadratic Shepard interpolant in ID. Since the version thus developed does not interpolate the given or estimated slopes, the need for a slope interpolating constrained Modified Quadratic Shepard interpolant was felt. In this paper, we constrain the Modified Quadratic Shepard interpolant to preserve positivity in one-dimensional interpolation such that the constrained interpolant also interpolates the slope data. We replace each basis function, by a positive spline which interpolates both the associated data point and slope at the data point while constraining the original curve to be positive. The extra knot in the spline provides the necessary flexibility which we avail for slope interpolation required. (author)

174

DOWNWARD SLOPING DEMAND CURVES FOR STOCK AND LEVERAGE  

Directory of Open Access Journals (Sweden)

Full Text Available This research attempts to investigate the effect of downward sloping demand curves for stock on firms' financing decisions. For the same size of equity issuance, firms with steeper slope of demand curves for their stocks experience a larger price drop in their share price compare to their counterparts. As a consequence, firms with a steeper slope of demand curves are less likely to issue equity and hence they have higher leverage ratios. This research finds that the steeper the slope of demand curve for firm's stock, the higher the actual leverage of the firm. Furthermore, firms with a steeper slope of demand curves have higher target leverage ratios, signifying that these firms prefer debt to equity financing in order to avoid the adverse price impact of equity issuance on their share price.

Liem Pei Fun

2006-01-01

175

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

176

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

177

?PPLICATION OF A METHOD OF INSURANCE PROTECTION AT RADIATING POLLUTION IN SLOPE`S ECOSYSTEMS  

Directory of Open Access Journals (Sweden)

Full Text Available The worked out chamber models of typical slope ecosystems allowed to conduct the estimationof collective dose and radiation risks for a population which uses these ecosystems. On this basisthe calculation of the expected losses is conducted from the dose loading estimation of collectiveand individual risks and losses. An algorithm and chart of insurance defence of population areoffered for this type of ecosystems. It is shown what an algorithm is offered it is possible to applyfor insurance defence people in other types of ecosystems and radiation situations

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

2011-04-01

178

Management of the Nkomati Mine crusher slope failure  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Due to limited available level ground, Nkomati Nickel Mine cut a weathered rock slope at the base of a mountain spur in order to create a platform for construction of the primary crusher plant and run-of-mine stockpiles. As space is limited around the mining area, ore processing at Nkomati is based [...] on a high reliability of flow of material through the crusher plant, with minimal usage of other and larger designed stockpiles. Evidently, any crusher plant shutdown will render the mine as a whole unproductive and put excessive strain on the medium- to long-term large ore stockpiles, the deposition rates for which are restricted by founding material consolidation requirements. At the onset of the 2012 rainy season, movement was identified on the slope monitoring system and cracks developed on the slope. After a minor failure on the crusher slope an assessment of the slope stability was conducted and a slope management plan recommended, which included deployment of real-time monitoring. An evaluation of the conditions leading to instability was conducted and the likely causes for the failure identified. A full evaluation of the slope monitoring, rainfall, and mining conditions was undertaken and movement triggers were determined. This paper describes the events leading to the development of the failure and the evaluation of the monitoring data to determine a management plan for the failure that allowed for minimal shutdowns of the primary crusher.

R., Armstrong; K., Moletsane.

2014-10-01

179

ALASKA NORTH SLOPE OIL-FIELD RESTORATION RESEARCH STRATEGY (ANSORRS)  

Science.gov (United States)

This document provides a research strategy to support ecological restoration of disturbances related to oil and gas developments on the North Slope of Alaska that is mutually beneficial to the arctic ecorestoration research community and the arctic regulatory community (including...

180

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

 
 
 
 
181

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

182

Systems of linear inequalities in slope-intercept form  

Science.gov (United States)

Compare a system of linear inequalities in slope-intercept form to its graph. Vary the coefficients and inequality symbols in the system. Explore how the boundary lines, shaded regions, and the intersection of the shaded regions change in response.

Exploremath.com; Glazer, Evan

2001-01-01

183

The stability of grounding lines on retrograde slopes  

Science.gov (United States)

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.

Gudmundsson, G. H.; Krug, J.; Durand, G.; Favier, L.; Gagliardini, O.

2012-12-01

184

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

185

Submarine landslides along the eastern Mediterranean Israeli continental slope  

Science.gov (United States)

Numerous shallow submarine slope failures (scars and deposits) are observed in recent high resolution bathymetric grids of the continental slope off the Israeli eastern Mediterranean coast. The nature of these slope failures is currently not comprehensively understood as well as the question of whether the eastern Mediterranean continental slope is continuously or episodically unstable. We report here first steps towards understanding the present state of this submarine landslide system, which include mapping and analyzing the geology of the landslides and the hosting slopes. The continental slope extends from water depths of about 150 to more than 1000 meters with a slope of less than 5 degrees in general. Bathymetric grids with pixel resolution of 15 m till water depth of 700 m and 50 m till water depth of 1700 m were used. Analyzing the bathymetry revealed three main submarine surface features: (a) numerous shallow landslides, within the upper sequence of the post-Messenian sediments. Landslide widths range between hundreds to thousand of meters at the scar, with scar heights up to hundred meters. The toes of the landslides are not always mapable and lay up to a few kilometers down slope from the scar. Slope angles within the scars are 5 to more than15 degrees. At least two types of landslides were detected: presumably young slides with sharp scars, and presumably old slides with secondary slides and secondary drainage systems developed within the scar area; (b) a few kilometers long, north striking step-like lineaments. Step heights are up to 100 meters and the slopes are up to 20 degrees. The offset between parallel steps is less than a kilometer to a few kilometers. The steps are interpreted as surface expressions of growth faults rooted at the Messinian evaporates up to 1.5 kilometers below surface; (c) a few north striking channels were also detected with steep walls of more than 15 degrees, up to two kilometers width and a few kilometers length. The nature of these channels is not clear yet. Field relations show that the landslides, both young and old, either emerge from the over-steepened steps, or are displaced by them, and hence submarine landslides and steps are apparently contemporaneous. In addition this suggests that salt dynamics at depth is a main drive for at least some of these shallow slides. The above preliminary results testify to the complicated and highly dynamic nature of the studied continental slope, yet to be revealed.

Reuven, Einav; Katz, Oded; Aharonov, Einat

2013-04-01

186

Numerical simulations of dense water cascading on a steep slope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The sinking of dense shelf waters down the continental slope (or "cascading") contributes to oceanic water mass formation and carbon cycling. Cascading over steep bottom topography is studied here in numerical experiments using POLCOMS, a 3-D ocean circulation model using 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 conical slope in a rotating tank. The governing parameters of the exper...

Wobus, Fred; Shapiro, Georgy I.; Maqueda, Miguel A. M.; Huthnance, John M.

2011-01-01

187

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

188

Alternative method for direct measurement of tibial slope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background/Aim. The tibial slope is one of the most frequently cited anatomical causes of anterior cruciate ligament trauma. The aim of this study was to determine the possibility of direct measuring of the tibial slope of the knee without prior soft tissue dissection in cadavers. Methods. Measurement was performed on the two groups of samples: osteological and cadaveric. The osteological group consisted of 102 matured tibiae and measurement was performed: ...

Stijak Lazar; Santra?-Stijak Gordana; Spasojevi? Goran; Radonji? Vidosava; Mališ Miloš; Milovanovi? Darko; Filipovi? Branislav

2014-01-01

189

Topographic slope correction for analysis of thermal infrared images  

Science.gov (United States)

A simple topographic slope correction using a linearized thermal model and assuming slopes less than about 20 degrees is presented. The correction can be used to analyzed individual thermal images or composite products such as temperature difference or thermal inertia. Simple curves are provided for latitudes of 30 and 50 degrees. The form is easily adapted for analysis of HCMM images using the DMA digital terrain data.

Watson, K. (princpal investigator)

1982-01-01

190

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...

Aryal, Krishna Prasad

2006-01-01

191

Slope stability analyses in complex Geotechnical conditions Thurst failure mechanism  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this thesis a previously unknown mechanism of failure in multilayered slope profiles is identified. In some conditions this mechanism does not confirm to the known failure models (relating to circular failure) used in slope stability analysis. For this reason, major failures have occurred in the artificial cuts despite the fact that the limit equilibrium methods suggest that these cuts would be stable. The limit equilibrium methods were originally created to apply to earth dam walls. In th...

Karparov, Krassimir Nikolov

2007-01-01

192

Hybrid Method for Analysis and Design of Slope Stabilizing Piles  

Digital Repository Infrastructure Vision for European Research (DRIVER)

iles are extensively used as a means of slope stabilization. Despite the rapid advances in computing and software power, the design of such piles may still include a high degree of conservatism stemming from the use of simplified easy to apply methodologies. This paper develops a hybrid method for designing slope stabilizing piles, combining the accuracy of rigorous 3D finite element (FE) simulation with the simplicity of widely accepted analytical techniques. It comprises two steps : (a) eva...

Kourkoulis, Rallis; Gelagoti, Fani; Anastasopoulos, Ioannis; Gazetas, George

2011-01-01

193

Noncommutative/nonlinear BPS equations without zero slope limit  

International Nuclear Information System (INIS)

It is widely believed that the linearly realized BPS equation in the non-commutative space is related to the non-linearly realized BPS equation in the commutative space in the zero slope limit. We shall show that the relation also holds without taking the zero slope limit as is expected from arguments of the BPS equation for the non-Abelian Born-Infeld theory. This is regarded as an evidence for the relation between the two BPS equations. (author)

194

Performance of the APS optical slope measuring system  

International Nuclear Information System (INIS)

An optical slope measuring system (OSMS) was recently brought into operation at the Advanced Photon Source of the Argonne National Laboratory. This system is equipped with a precision autocollimator and a very accurate mirror-based pentaprism on a scanning stage and kept in an environment-controlled enclosure. This system has the capability to measure precision optics with sub-microradian rms slope errors as documented with a series of tests demonstrating accuracy, stability, reliability and repeatability. Measurements of a flat mirror with 0.2 ?rad rms slope error are presented which show that the variation of the slope profile measurements with the mirror setting at different locations along the scanning direction is only 60 nrad and the corresponding height error profile has 2 nm rms. -- Highlights: ? This is the first time to present the APS OSMS in publication. ? The APS OSMS is capable to measure flat and near flat mirrors with slope error <100 nrad rms. ? The accuracy of the slope error measurements of a 350 mm long mirror is less than 60 nrad rms

195

Relating weak layer and slab properties to snow slope stability  

Directory of Open Access Journals (Sweden)

Full Text Available Snow slope stability evaluation requires considering weak layer as well as slab properties – and in particular their interaction. We developed a stability index from snow micro-penetrometer measurements and compared it to 129 concurrent point observations with the compression test (CT. The index considers the SMP-derived micro-structural strength and the additional load which depends on the hardness of the surface layers. The new quantitative measure of stability discriminated well between point observations rated as either "poor" or "fair" (CT < 19 and those rated as "good" (CT ? 19. However, discrimination power within the intermediate range was low. We then applied the index to gridded snow micro-penetrometer measurements from 11 snow slopes to explore the spatial structure and possibly relate it to slope stability. Stability distributions on the 11 slopes reflected various possible strength and load (stress distributions that naturally can occur. Their relation to slope stability was poor possibly because the index does not consider crack propagation. Hence, the relation between spatial patterns of point stability and slope stability remains elusive. Whereas this is the first attempt of a truly quantitative measure of stability, future developments should consider a better reference of stability and incorporate a measure of crack propagation.

J. Schweizer

2014-07-01

196

Problems of definitive slopes mining at Doly Nastup Tusimice  

International Nuclear Information System (INIS)

The instability of slopes influents mining business in many aspects at open-cast mining. The temporary decrease of intended mined volumes due to land slips 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 important. Monitoring of rock massive stability plays an important role. Everything which stability of slopes is concerned belongs to essential tasks for mining technicians at open-cast mining. The article explains what ways for definitive slope formation near mining boundary were selected at Severoceske doly j.s.c., Doly Nastup Tusimice mining site. The precautions refer to mining technology, preventive and reconstruction precautions for stabilization of slopes must to solve, are to described. Tasks, which mining engineers, surveyors, geologists and geotechnics have to solve are described. (authors)

197

Alternative method for direct measurement of tibial slope  

Directory of Open Access Journals (Sweden)

Full Text Available Background/Aim. The tibial slope is one of the most frequently cited anatomical causes of anterior cruciate ligament trauma. The aim of this study was to determine the possibility of direct measuring of the tibial slope of the knee without prior soft tissue dissection in cadavers. Methods. Measurement was performed on the two groups of samples: osteological and cadaveric. The osteological group consisted of 102 matured tibiae and measurement was performed: indirectly by sagittal photographing of the tibia, and directly by a set of parallel bars. The cadaveric group consisted of 50 cadaveric knees and measurement was performed directly by a set of parallel bars. The difference and correlation between indirect and the direct measurements were observed, which included also measuring of the difference and correlation of the tibial slope on the medial and lateral condyles. Results. A statistically significant difference between the direct and indirect method of measuring (p 0.05. However, the slope on the medial condyle, as well as indirect measurement showed a statistically significant difference (p < 0.01. Conclusion. By the use of a set of parallel bars it is possible to measure the tibial slope directly without removal of the soft tissue. The results of indirect, photographic measurement did not statistically differ from the results of direct measurement of the tibial slope.

Stijak Lazar

2014-01-01

198

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

199

78 FR 4870 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority...

2013-01-23

200

77 FR 21806 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority...

2012-04-11

 
 
 
 
201

75 FR 39971 - Notice of Reestablishment of the North Slope Science Initiative Science Technical Advisory Panel  

Science.gov (United States)

...Land Management's (BLM) North Slope Science Initiative (NSSI) Science...monitoring, and research needed on the North Slope of Alaska, including the off-shore environments...that the reestablishment of the North Slope Science Initiative Science...

2010-07-13

202

76 FR 79211 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority...

2011-12-21

203

76 FR 55943 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority...

2011-09-09

204

77 FR 46769 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority...

2012-08-06

205

76 FR 10388 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority...

2011-02-24

206

75 FR 17433 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority needs...

2010-04-06

207

75 FR 52370 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative-Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority needs...

2010-08-25

208

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

Science.gov (United States)

...for Nominations: North Slope Science Initiative...Advisory Panel, Alaska AGENCY: Bureau of Land Management, Alaska State Office, North Slope Science Initiative...resources on the North Slope of Alaska and the...

2013-06-26

209

76 FR 56789 - Call for Nominations: North Slope Science Initiative, Science Technical Advisory Panel, Alaska  

Science.gov (United States)

...Nominations: North Slope Science Initiative...Advisory Panel, Alaska AGENCY: Bureau...Director, North Slope Science Initiative...Management, Alaska State Office...experience in Alaska in their field...preferably in the North Slope region....

2011-09-14

210

75 FR 79017 - Notice of Public Meeting, North Slope Science Initiative-Science Technical Advisory Panel  

Science.gov (United States)

...Notice of Public Meeting, North Slope Science Initiative--Science...Bureau of Land Management, Alaska State Office, North Slope Science Initiative, Interior...management decisions across the North Slope of Alaska. These priority...

2010-12-17

211

75 FR 159 - Notice of Public Meeting, North Slope Science Initiative, Science Technical Advisory Panel, Alaska  

Science.gov (United States)

...Public Meeting, North Slope Science Initiative...Advisory Panel, Alaska AGENCY: Bureau of Land Management, Alaska State Office, North Slope Science Initiative...decisions across the North Slope of Alaska. These...

2010-01-04

212

Slope stability along active and passive continental margins: a geotechnical approach  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Submarine mass movements are widespread at submarine slopes and play an important role in transporting sediments across the continental slope to the deep basin, as well as potential danger to both offshore infrastructures (e.g., pipeline, cables and platforms) and coastal areas (e.g., slope failure-induced tsunamis). Sliding of the sediments on continental slope takes place when the shear stress within sediments exceeds the shear strength thereby causing slope failure. Slope failures are gene...

Ai, Fei

2013-01-01

213

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

214

Comprehensive evaluation of high-steep slope stability and optimal high-steep slope design by 3D physical modeling  

Science.gov (United States)

High-steep slope stability and its optimal excavation design in Shuichang open pit iron mine were analyzed based on a large 3D physical simulation technique. An optimal excavation scheme with a relatively steeper slope angle was successfully implemented at the northwest wall between Nos. 4 and 5 exploration lines of Shuichang Iron Mine, taking into account the 3D scale effect. The physico-mechanical properties of rock materials were obtained by laboratory tests conducted on sample cores from exploration drilling directly from the iron mine. A porous rock-like composite material was formed for the model, and the mechanical parameters of the material were assessed experimentally; specifically, the effect of water on the sample was quantitatively determined. We adopted an experimental setup using stiff modular applied static loading to carry out a visual excavation of the slope at a random depth. The setup was equipped with acoustic emission (AE) sensors, and the experiments were monitored by crack optical acquirement, ground penetrating radar, and close-field photogrammetry to investigate the mechanisms of rock-mass destabilization in the high-steep slope. For the complex study area, the model results indicated a clear correlation between the model's destabilization resulting from slope excavation and the collected monitoring information. During the model simulation, the overall angle of the slope increased by 1-6 degrees in different sections. Dramatically, the modeled excavation scheme saved over 80 million tons of rock from extraction, generating enormous economic and ecological benefits.

Lai, Xing-ping; Shan, Peng-fei; Cai, Mei-feng; Ren, Fen-hua; Tan, Wen-hui

2015-01-01

215

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

216

Simulation of a sloped solar chimney power plant in Lanzhou  

Energy Technology Data Exchange (ETDEWEB)

Research highlights: {yields} A sloped solar chimney power plant in Lanzhou, China is investigated. {yields} The configuration sizes are designed separately. {yields} The system has high periodicity and stability but low efficiency. {yields} 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 31{sup o} 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.

Cao, Fei [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an (China); Zhao, Liang, E-mail: lzhao@mail.xjtu.edu.c [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an (China); Guo, Liejin [State Key Laboratory of Multiphase Flow in Power Engineering, Xi' an Jiaotong University, Xi' an (China)

2011-06-15

217

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 sol 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.

218

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.

219

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  

Directory of Open Access Journals (Sweden)

Full Text Available 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 técnica 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.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

2011-01-01

220

The slope aspect: A predisposing factor for landsliding?  

Science.gov (United States)

The influence of slope aspect on the distribution of landslides was studied in the Milia and Roglio basins in Tuscany, Italy. For each basin, the new Tuscany region landslide inventory that was initiated in 2010 was used. The landslides were split into separate datasets based on their prevailing movement typology. To assess the results that were obtained from the different slope aspect values, maps of the lithology, slope angle, distances to streams, and distances to tectonic lineaments were included in the bivariate statistical analysis as comparison terms. For each basin, all of the geo-environmental factor maps were compared with the different landslide typologies with GIS software. Pearson's Chi2 (?2) coefficient was used to test the degree of spatial association between each predictor variable and landslide type. In addition, Cramer's V test was used to quantify the strength of the degree of association. Next, a conditional analysis was applied to all of the possible combinations that occurred between the slope aspect and other landslide-predisposing factors. Overall, the slope aspect significantly affected the distribution of superficial landslide types, but apparently not that of other landslide types.

Capitani, Marco; Ribolini, Adriano; Bini, Monica

2013-11-01

 
 
 
 
221

Kinematics of running at different slopes and speeds.  

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The aim of this study was to verify the influence of the combination of different running speeds and slopes based on main kinematic parameters in both groups of elite (RE) and amateur (RA) marathon runners. All subjects performed various tests on a treadmill at 0, 2, and 7% slopes at different speeds: 3.89, 4.17, 4.44, 4.72, and 5.00 m·s. A high speed digital camera, 210 Hz, has been used to record; Dartfish 5.5Pro has been used to perform a 2D video analysis. Step length (SL), step frequency (SF), flight time (FT), and contact time (CT) were determined and used for comparison. SL, SF, and FT parameters increased, and CT parameter decreased as speed increased. As slopes increased, SL and FT decreased and SF increased in both groups and only CT decreased in RE, whereas in RA, it increased. Data were fitted to the linear regression line (R > 0.95). The 2 groups were significantly different (p speeds in level running. A significant difference between the 2 groups was found in FT at 2 and 7% slopes at all speeds (p speed but also by slopes. Elite runners perform more efficiently than amateur runners who have less experience. PMID:22126973

Padulo, Johnny; Annino, Giuseppe; Migliaccio, Gian M; D?ottavio, Stefano; Tihanyi, József

2012-05-01

222

High-Order FEM Formulation for 3-D Slope Instability  

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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

223

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

224

Reflection of a long wave from an underwater slope  

Science.gov (United States)

Reflection of long sea waves from an underwater slope described by a power law is studied within the shallow water theory. The slope is connected with the flat bottom. This model allows us to estimate the roles of a pointwise reflection from the inflection point of the bottom profile and distributed reflection at the underwater slope. The case of the underwater slope described by the so-called nonreflecting beach ( h( x) ˜ x 4/3, where h is the depth of the basin and x is the coordinate) when the wave is reflected only from the inflection point (pointwise reflection) is specially considered. The reflection and transmission coefficients over the bottom topography were calculated, and it was shown that the sum of the squared absolute values of these values differs from unity for all profiles except the nonreflecting one. This difference is related to the distributed re-reflections (resonances) over the underwater slope that lead to the deviations in the wave height from the known Green's law.

Didenkulova, I. I.; Pelinovsky, E. N.

2011-08-01

225

Retrieval of short ocean wave slope using polarimetric imaging  

International Nuclear Information System (INIS)

We present a passive optical remote sensing technique for recovering shape information about a water surface, in the form of a two-dimensional slope map. The method, known as polarimetric slope sensing (PSS), uses the relationship between surface orientation and the change in polarization of reflected light to infer the instantaneous two-dimensional slope across the field-of-view of an imaging polarimeter. For unpolarized skylight, the polarization orientation and degree of linear polarization of the reflected skylight provide sufficient information to determine the local surface slope vectors. A controlled laboratory experiment was carried out in a wave tank with mechanically generated gravity waves. A second study was performed from a pier on the Hudson River, near Lamont-Doherty Earth Observatory. We demonstrated that the two-dimensional slope field of short gravity waves could be recovered accurately without interfering with the fluid dynamics of the air or water, and water surface features appear remarkably realistic. The combined field and laboratory results demonstrate that the polarimetric camera gives a robust characterization of the fine-scale surface wave features that are intrinsic to wind-driven air–sea interaction processes

226

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

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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

227

A preliminary pit slope stability study Kvanefjeld, South Greenland  

International Nuclear Information System (INIS)

On the basis of 1300 field measurements of joint planes, four individual structural regions have been outlined in the Kvanefjeld area. Potential failure planes and planes which are unlikely to be involved in slope failures are identified. Failures seem, not likely to occur on walls dipping SW or NE respectively, but may occur on walls dipping NM. The factors of safety for each region are calculated in order to determine the sensibility of the overall slope to different overall slope angles. The factors of safety does only exceed the required factor of safety of 1.5 in one of the structural regions. Changing the overall pit slope inclination from 55deg to 45deg improves the security, but even still not satisfactorily for two of the regions. At 45deg overall pit slope in parts of the pit implies additional 14.3 x 106 tonnes of non-mineralized material to be mined, thus resulting in a total mineralized- to non-mineralized material ratio about 1.0: 1.7. (author)

228

The influence of slope breaks on lava flow surface disruption  

Science.gov (United States)

in the underlying slope of a lava flow impart a significant fraction of rotational energy beyond the slope break. The eddies, circulation, and vortices caused by this rotational energy can disrupt the flow surface, having a significant impact on heat loss and thus the distance the flow can travel. A basic mechanics model is used to compute the rotational energy caused by a slope change. The gain in rotational energy is deposited into an eddy of radius R whose energy is dissipated as it travels downstream. A model of eddy friction with the ambient lava is used to compute the time-rate of energy dissipation. The key parameter of the dissipation rate is shown to be ?R2/?, where ? is the lava density and ? is the viscosity, which can vary by orders of magnitude for different flows. The potential spatial disruption of the lava flow surface is investigated by introducing steady state models for the main flow beyond the steepening slope break. One model applies to slow-moving flows with both gravity and pressure as the driving forces. The other model applies to fast-moving, low-viscosity, turbulent flows. These models provide the flow velocity that establishes the downstream transport distance of disrupting eddies before they dissipate. The potential influence of slope breaks is discussed in connection with field studies of lava flows from the 1801 Hualalai and 1823 Keaiwa Kilauea, Hawaii, and 2004 Etna eruptions.

Glaze, Lori S.; Baloga, Stephen M.; Fagents, Sarah A.; Wright, Robert

2014-03-01

229

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

230

Model slope infiltration experiments for shallow landslides early warning  

Science.gov (United States)

Occurrence of fast landslides has become more and more dangerous during the last decades, due to the increased density of settlements, industrial plants and infrastructures. Such problem is particularly worrying in Campania (Southern Italy), where the fast population growth led a diffuse building activity without planning: indeed, recent flowslides caused hundreds of victims and heavy damages to buildings, roads and other infrastructures. Large mountainous areas in Campania are mantled by loose pyroclastic granular soils up to a depth of a few meters from top soil surface. These soils have usually a grain size that falls in the domain of silty sands, including pumice interbeds (gravelly sands), with saturated hydraulic conductivities up to the order of 10-1 cm/min. Such deposits often cover steep slopes, which stability is guaranteed by the apparent cohesion due to suction under unsaturated conditions, that are the most common conditions for these slopes [Olivares and Picarelli, 2001]. Whereas rainfall infiltration causes soil to approach saturation, suction vanishes and slope failure may occur. Besides soil physical properties, landslide triggering is influenced by several factors, such as rainfall intensity, soil initial moisture and suction, slope inclination, boundary conditions. Whereas slope failure occurs with soil close to being saturated, landslide may develop in form of fast and destructive flowslide. Calibration of reliable mathematical models of such a complex phenomenon requires availability of experimental observations of the major variables of interest, such as soil moisture and suction, soil deformation and displacements, pore water pressure, during the entire process of infiltration until slope failure. Due to the sudden trigger and extremely rapid propagation of such type of landslides, such data sets are rarely available for natural slopes where flowslides occurred. As a consequence landslide risk assessment and early warning in Campania rely on simple empirical models [Versace et al., 2003] based on correlation between some features of rainfall records (cumulated height, duration, season etc.) and the correspondent observed landslides. Laboratory experiments on instrumented small scale slope models represent an effective way to provide data sets [Eckersley, 1990; Wang and Sassa, 2001] useful for building up more complex models of landslide triggering prediction. At the Geotechnical Laboratory of C.I.R.I.AM. an instrumented flume to investigate on the mechanics of landslides in unsaturated deposits of granular soils is available [Olivares et al. 2003; Damiano, 2004; Olivares et al., 2007]. In the flume a model slope is reconstituted by a moist-tamping technique and subjected to an artificial uniform rainfall since failure happens. The state of stress and strain of the slope is monitored during the entire test starting from the infiltration process since the early post-failure stage: the monitoring system is constituted by several mini-tensiometers placed at different locations and depths, to measure suction, mini-transducers to measure positive pore pressures, laser sensors, to measure settlements of the ground surface, and high definition video-cameras to obtain, through a software (PIV) appositely dedicated, the overall horizontal displacement field. Besides, TDR sensors, used with an innovative technique [Greco, 2006], allow to reconstruct the water content profile of soil along the entire thickness of the investigated deposit and to monitor its continuous changes during infiltration. In this paper a series of laboratory tests carried out on model slopes in granular pyroclastic soils taken in the mountainous area north-eastern of Napoli, are presented. The experimental results demonstrate the completeness of information provided by the various sensors installed. In particular, very useful information is given by the coupled measurements of soil water content by TDR and suction by tensiometers. Knowledge of soil water content at the occurrence of slope failure is of key importance, since high soil mo

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

2009-04-01

231

Extensive slope currents and the ocean-shelf boundary  

Science.gov (United States)

Slope currents are one manifestation of ocean-shelf interaction, which is reviewed for length scales comparable with or greater than the shelf or slope width. Coastal trapped wave forms provide a basis for describing sub-inertial-frequency flow in the shelf-slope context. Such waves propagate cyclonically around ocean basins (a bias extending to energy propagation) and eventually decay through energy loss by friction, scattering or radiation. I discuss implications for remote forcing, for the along-shelf development of forced flows of all kinds, for the on-shelf penetration of oceanic flow structures (according to length and frequency scales and the degree of dissipation) and hence for coastal monitoring of oceanic circulation. Implications for models are emphasised.

Huthnance, J. M.

232

Wetting Front Advance From a Point Source in Sloping Fields  

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Full Text Available To determine the effects of field slope, emitter discharge, irrigation water volume and soil texture on soil moisture profile and soil surface wetted shape from a point source, field data were collected on three different soil types, three emitter discharges (4, 8, and 12 lph, four slopes (0, 2, 5, and 10%, and five irrigation water volumes (10, 20, 30, 40, and 50 liters with three replications. The results showed that the surface-wetted area increases as the emitter discharge increases. The surface-wetted area decreased with a corresponding increase in emitter discharge in experimental fields with light-textured soils. In experimental fields with heavy textured soils and slopes greater than 5%, the changes in surface-wetted area due to the emitter discharge increases, were higher compared to slopes of less than 5%. Since, a higher emitter discharge would result in higher surface-wetted area, the results showed that for an equal volume of irrigation water, the soil moisture profile was deeper for lower emitter discharge. In general, the volume of wetted zone was higher for greater emitter discharges. It was found that as the volume of irrigation water increased, the volume of wetted zone would increase correspondingly. This effect is more prominent than that of emitter discharge. In general, the depth of wetting front was lower and the wetted surface area was greater for heavy textured soils as compared to the light textured soils. The wetted-surface area and the shape of wetting front in the direction of slope were affected by the soil infiltration, emitter discharge and volume of irrigation water where these effects were more critical in higher sloping lands.

Behrouz Mostafazadeh

1998-10-01

233

Preliminary Slope-Stability Analysis of Augustine Volcano  

Science.gov (United States)

Augustine Volcano has been a prolific producer of large debris avalanches during the Holocene. Originating as landslides from the steep upper edifice, these avalanches typically slide into the surrounding ocean. At least one debris avalanche that occurred in 1883 during an eruption initiated a far-traveled tsunami. The possible occurrence of another edifice collapse and ensuing tsunami was a concern during the 2006 eruption of Augustine. To aid in hazard assessments, we have evaluated the slope stability of Augustine's edifice, using a quasi-three-dimensional, geotechnically based slope-stability model implemented in the computer program SCOOPS. We analyzed the effects of topography, variations in rock strength, and earthquake-induced strong ground motion on the relative stability of millions of potential large (>0.1 km3 volume) slope failures throughout the edifice. Preliminary results from pre-2006 topography provide three insights. First, the predicted stability of all parts of the upper edifice is approximately the same, suggesting an equal likelihood of slope failure, in agreement with geologic observations that debris avalanches have swept all sectors of the volcano. Second, the least stable (by a small amount) sector is on the east flank where a debris avalanche would flow into deeper ocean water and a resulting tsunami would be directed toward the southwestern part of the Kenai Peninsula. Third, most model scenarios predict stable edifice slopes, and only scenarios assuming extensive weak rocks and moderate to strong ground shaking predict potential large collapses. Because other transient triggering mechanisms, such as shallow magma intrusion, may be needed to instigate slope instability, monitoring ground deformation and seismicity could

Reid, Mark E.; Brien, Dianne L.; Waythomas, Christopher F.

2010-01-01

234

Neotectonics of The Eastern Sicily Slope and Its Geodynamic Significance  

Science.gov (United States)

Along the presently active margin between Africa and Europe the nature of the sub- ducted plate changes from oceanic to continental across the eastern Sicily slope, where the oceanic Ionian lithosphere passes to the west to the continental Hyblean-Pelagian lithosphere. Both tectonic structures and seismicity indicate a peculiar neotectonic ac- tivity along the eastern Sicily slope. The Malta Escarpment (ME) represents the dom- inant morphological feature offshore eastern Sicily and appears as a steep, eastward- sloping surface partly onlapped by the flat laying sediments of the adjacent Ionian basin. On the basis of a recent MCS survey carried out in the eastern Sicily offshore the ME can be divided into two portions characterised by different tectonic structures. Along the segment south of Siracusa the ME is not affected by recent faulting and appears as a steep surface that flattens out towards the Ionian basin. The escarpment appears as an original slope, likely inherited from Mesozoic (or earlier) time, linking the deep Ionian basin to the east with the Hyblean carbonate platform to the west. A recent deformation, characterised by a broad area of uplift, occurs 20 - 30 km east from the slope, along a NNW-SSE trend. The segment of the ME extending north of Siracusa, on the other hand, is characterised by the presence of recent NNW-SSE, east- dipping extensional faults located along the morphological escarpment and a few km east of it. In some instances the easternmost extensional faults, and related sedimen- tary basins, are affected by contractional deformation. The neotectonics of the eastern Sicily slope is related to the final stage of the southern Tyrrhenian backarc opening, driven by the rollback of the Ionian subduction, and reflects the complex interaction between the lateral ramp of the Calabrian Arc accretionary wedge, in the upper plate, and the scissors-like tearing apart, within the lower plate, between the sinking Ionian slab and the buoyant Hyblean-Pelagian lithosphere.

Argnani, A.; Bonazzi, C.

235

Channel Slopes on Amazon Basin Rivers From the SRTM DEM  

Science.gov (United States)

Changes in surface water storage (S) and discharge (Q) are poorly known globally but are critical for constraining the terrestrial branch of the water cycle. To date, only the SRTM mission provides global measurements of both surface water area and elevation. However, little is known about the instrument performance for collecting delta-S and Q. The Amazon Basin is a particularly appealing target given its sparse gauge density, lack of continuous and reliable slope data that can be used in the estimation of discharge, and complexity of flow hydraulics. We have used SRTM elevation data in conjunction with flow distance to estimate water surface slope for the area 0S-8S, 72W-54W. Using a 3rd order polynomial fit to the distance-elevation data, slope values of the mainstem Amazon range from less than 0.5 cm km-1 downstream of Obidos to 4.10 cm km-1 3000 km upstream of this location. The central Amazon slope ranges from 1.86 cm km-1 to 3.10 cm km-1 from Manaus to the Rio Japura (about 800 km upstream). Local slopes for specific gauge locations were achieved using both a linear fit to the data and the polynomial fit. The slope value at Itapeua, about 430 km upstream of Manaus, was found to be 3.22 cm km-1 using a linear fit, and 2.65 - 2.79 cm km-1 using a 3rd order polynomial fit, for a reach of 24 km. The slope value for Manacapuru, about 90 km upstream of Manaus, was determined to be 3.56 cm km-1 using a linear fit and 1.97 - 2.12 cm km-1 for a reach of 70 km centered on the local gauge. This slope is used in the Manning equation (n = 0.03) with depth values from navigation charts and river width measured from JERS-1 SAR imagery to yield discharge values for Manacapuru of 93,500 m3 sec-1and for Itapeua of 81,900 m3 sec-1. The observed discharge value at the Manacapuru gauge is 96,300 m3 sec-1 over an 11-day average in February for the years 1973-1991. The average observed discharge value for Itapeua is 83,100 m3 sec-1 for the same time period.

Hendricks, G.; Alsdorf, D. E.

2004-12-01

236

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

237

The F1 ledge: density, height and slope  

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Full Text Available Diurnal variations of the F1 region ionization at 170 km altitude and the slope ?170 = dN/dh at this height are analyzed for mid-latitude and equatorial stations: Millstone Hill, Ramey, Puerto Madryn and Jicamarca. Both the density N(t and the slope ?(tat 170 km show well defined diurnal variations with day-to-day variabilities of less than 10%. The heights of the F1 ledge, hmF1, are spread over ± 20 km and are therefore of limited value for modeling purposes.

X. Huang

1996-06-01

238

Analytical approximation for the recession of a sloping aquifer  

Science.gov (United States)

approximation is obtained for the recession of a sloping aquifer. The analytical approximation can provide a useful tool to analyze data and obtain physical properties of the aquifer. In contrast to the case of a horizontal aquifer, when plotting the time derivative of the flux versus the flux on a log scale, the result shows that the flux derivative reaches a minimum value and that the curve can have a slope of unity as often observed. Illustration of the application of the analytical results to the Mahantango Creek data is also discussed.

Hogarth, W. L.; Li, L.; Lockington, D. A.; Stagnitti, F.; Parlange, M. B.; Barry, D. A.; Steenhuis, T. S.; Parlange, J.-Y.

2014-11-01

239

Resonant generation of internal waves on a model continental slope.  

Science.gov (United States)

We study internal wave generation in a laboratory model of oscillating tidal flow on a continental margin. Waves are found to be generated only in a near-critical region where the slope of the bottom topography matches that of internal waves. Fluid motion with a velocity an order of magnitude larger than that of the forcing occurs within a thin boundary layer above the bottom surface. The resonant wave is unstable because of strong shear; Kelvin-Helmholtz billows precede wave breaking. This work provides a new explanation for the intense boundary flows on continental slopes. PMID:18643589

Zhang, H P; King, B; Swinney, Harry L

2008-06-20

240

Spatial distribution models of erosion on slopes cultivated with vineyards  

International Nuclear Information System (INIS)

Soils cultivated with vineyards have high rates of erosion. In the Mediterranean area, this is related to the environmental characteristics and the management of cultivation techniques. Indeed, in this region the rainfall intensity and the location of vineyards on slopes favour the erosive activity of runoff. The total area of vineyards in La Rioja (Spain) is currently almost 40,000 ha. Vineyards are located on hillsides between 400 and 60 m.a.s.l. Of the vineyards of La Rioja 81,7% are planted on slopes with a gradient between 3 degree centigrade and 9 degree centigrade. (Author) 5 refs.

 
 
 
 
241

Development of deep-seated gravitational slope deformation on a shale dip-slope: observations from high-quality drillcores  

Science.gov (United States)

The internal structures within a gravitationally deformed slope were observed using high-quality drillcores obtained from a dip slope of a series of shale-dominated sediments. This slope has dimple-like depressions and an overall gentle slope angle, but has no well-defined landslide scarp, suggesting that this area underwent gravitationally deformation but with no separation of the deformed portion from the surrounding area. Three drillcores, to a maximum depth of 96 m, were used during this study, with detailed observations of cut paraffin-impregnated core surfaces used to characterize gravitational deformation in the study area. This logging identified shear zones that consist of disintegrated (brecciated) and pulverized zones that were up to 88 and 19 cm thick, respectively. Disintegrated zone breccias have local jigsaw-fit textures, but other areas contain compositional trails formed by cataclastic flow, and rounded outlines formed by attrition. Pulverized zones underwent increased amounts of shearing, leading to the formation of more rounded fragments and increasing amounts of clayey matrix material, but still containing more than 30% of visible rock fragments. As such, these zones are still classified as breccias in terms of fault rock classification. Planar structures, such as R and Y shears, and P foliations, are not developed in the study area. Shear zones are intermittently located across the slope and have not formed a through-going master sliding zone. Incipient shear zones are present within the slope, including a pair of shear surfaces with a pull apart-like opening, and thin disintegrated or pulverized zones in intact rocks at 3-10 m below the base of the main area of gravitational deformation, suggesting that these shear zones propagate downward in a step-wise manner. This propagation may be related to the redistribution of stress induced by river incision.

Chigira, Masahiro; Hariyama, Takehiro; Yamasaki, Shintaro

2013-04-01

242

Behaviour of the slope parameter in the high elastic scattering  

International Nuclear Information System (INIS)

If the elastic pp total cross section grows as ln2 s, then so does the slope parameter B, measured inside the diffraction region. The apparent paradox arising from Martin's bound B(s, t) < C ln s at nearly fixed t is explained. (orig.)

243

A Nonparametric K-Sample Test for Equality of Slopes.  

Science.gov (United States)

The development of a nonparametric K-sample test for equality of slopes using Puri's generalized L statistic is presented. The test is recommended when the assumptions underlying the parametric model are violated. This procedure replaces original data with either ranks (for data with heavy tails) or normal scores (for data with light tails).…

Penfield, Douglas A.; Koffler, Stephen L.

1986-01-01

244

The slope of the Baryonic Tully-Fisher relation  

CERN Document Server

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 \\textrm{H\\,\\scriptsize{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 $\\Lambda$CDM cosmological simulations that include both stellar and gas baryons. The scatter in the TFR/BTFR appears to depend on $W_{20}$: galaxies that rotate slower have more scatter. The atomic gas--to--stars ratio shows a break near $W_{20} = 250$ \\kms\\, 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 evoluti...

Gurovich, Sebastián; Jerjen, Helmut; Staveley-Smith, Lister; Puerari, Ivânio

2010-01-01

245

The Slope of the Baryonic Tully-Fisher Relation  

Science.gov (United States)

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 W 20: galaxies that rotate slower have more scatter. The atomic gas-to-stars ratio shows a break near W 20 = 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.

Gurovich, Sebastián; Freeman, Kenneth; Jerjen, Helmut; Staveley-Smith, Lister; Puerari, Ivânio

2010-09-01

246

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.

247

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

248

Slope estimation and viewing distance of the observer.  

Science.gov (United States)

The overestimation of geographical slant is one of the most sizable visual illusions. However, in some cases estimates of close-by slopes within the range of the observer's personal space have been found to be rather accurate. We propose that the seemingly diverse findings can be reconciled when taking the viewing distance of the observer into account. The latter involves the distance of the observer from the slope (personal space, action space, and vista space) and also the eye-point relative to the slope. We separated these factors and compared outdoor judgments to those collected with a three-dimensional (3D) model of natural terrain, which was within arm's reach of the observer. Slope was overestimated in the outdoors at viewing distances between 2 m and 138 m. The 3D model reproduced the errors in monocular viewing; however, performance was accurate with stereoscopic viewing. We conclude that accurate slant perception breaks down as soon as the situation exits personal space, be it physically or be it by closing one eye. PMID:24927945

Hecht, Heiko; Shaffer, Dennis; Keshavarz, Behrang; Flint, Mariagrace

2014-08-01

249

Numerical photogrammetry in laboratory experiences on 2D slopes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this preliminary study a numerical photogrammetry system was tested in measuring incremental displacement fields in slope models realised with analogous Schneebeli material. Two tests were performed corresponding to different sets of boundary conditions on the displacements; controlled and uncontrolled deformation scenery were experienced. The resulting measures showed efficiency, limits and perspective of this measuring technique.

Froiio, Froiio; Viggiani, Gioacchino; Laouafa, Farid

2002-01-01

250

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

251

Soil organic carbon redistribution and budget of erosion and deposition in a sloping field  

International Nuclear Information System (INIS)

A sloping field of black soil in northeast China was selected to conduct soil redistribution for the past nearly 50 and 100 years, and to calculate the carbon budget by using 137Cs and fly ash tracer techniques. The results showed that the depth of original buried layer in foot-slope and toe-slope located at 70 and 80 cm respectively, and the content of SOC was 5.23 and 0.43 g/kg more than those of overlying soil. Summit, shoulder-slope and back-slope suffered erosion with the rate of 0.2, 5 and 2.2 mm/yr, respectively based on distribution of 137Cs and fly ash with soil depth. The depths of fly ash attainment in foot-slope and toe-slope were 70 and 80 cm respectively, and were well consistence with their buried surface horizon, which indicated the depositional areas had been annually plowed before locomotives used. Most of the eroded soil materials in depositional areas were from shoulder-slope and back-slope, accumulated in foot-slope firstly, then transferred to toe-slope gradually according to soil surface of various years. The loss of SOC in summit, shoulder-slope and back-slope was 683 kg in all in the past nearly 100 years, among which 418 kg (about 60%) was accumulated in foot-slope and toe-slope depressions, 257 kg of soil carbon was accumulated in most recent 50 years. (authors)

252

The dependence of sheet erosion velocity on slope angle  

Directory of Open Access Journals (Sweden)

Full Text Available The article presents a method for estimating the erosion velocity on forested natural area. As a research object for testing the methodology the authors selected Neskuchny Garden - a city Park on the Moskva river embankment, named after the cognominal Palace of Catherine's age. Here, an almost horizontal surface III of the Moskva river terrace above the flood-plain is especially remarkable, accentuated by the steep sides of the ravine parallel to St. Andrew's, but short and nameless. The crests of the ravine sides are sharp, which is the evidence of its recent formation, but the old trees on the slopes indicate that it has not been growing for at least 100 years. Earlier Russian researchers defined vertical velocity of sheet erosion for different regions and slopes with different parent (in relation to the soil rocks. The comparison of the velocities shows that climatic conditions, in the first approximation, do not have a decisive influence on the erosion velocity of silt loam soils. The velocities on the shores of Issyk-Kul lake and in Moscow proved to be the same. But the composition of the parent rocks strongly affects the sheet erosion velocity. Even low-strength rock material reduces the velocity by times. Phytoindication method gives a real, physically explainable sheet erosion velocities. The speed is rather small but it should be considered when designing long-term structures on the slopes composed of dispersive soils. On the slopes composed of rocky soils sheet erosion velocity is so insignificant that it shouldn't be taken into account when designing. However, there may be other geological processes, significantly disturbing the stability of slopes connected with cracks.

Chernyshev Sergey Nikolaevich

2014-09-01

253

Parallel processing for efficient 3D slope stability modelling  

Science.gov (United States)

We test the performance of the GIS-based, three-dimensional slope stability model r.slope.stability. The model was developed as a C- and python-based raster module of the GRASS GIS software. It considers the three-dimensional geometry of the sliding surface, adopting a modification of the model proposed by Hovland (1977), and revised and extended by Xie and co-workers (2006). Given a terrain elevation map and a set of relevant thematic layers, the model evaluates the stability of slopes for a large number of randomly selected potential slip surfaces, ellipsoidal or truncated in shape. Any single raster cell may be intersected by multiple sliding surfaces, each associated with a value of the factor of safety, FS. For each pixel, the minimum value of FS and the depth of the associated slip surface are stored. This information is used to obtain a spatial overview of the potentially unstable slopes in the study area. We test the model in the Collazzone area, Umbria, central Italy, an area known to be susceptible to landslides of different type and size. Availability of a comprehensive and detailed landslide inventory map allowed for a critical evaluation of the model results. The r.slope.stability code automatically splits the study area into a defined number of tiles, with proper overlap in order to provide the same statistical significance for the entire study area. The tiles are then processed in parallel by a given number of processors, exploiting a multi-purpose computing environment at CNR IRPI, Perugia. The map of the FS is obtained collecting the individual results, taking the minimum values on the overlapping cells. This procedure significantly reduces the processing time. We show how the gain in terms of processing time depends on the tile dimensions and on the number of cores.

Marchesini, Ivan; Mergili, Martin; Alvioli, Massimiliano; Metz, Markus; Schneider-Muntau, Barbara; Rossi, Mauro; Guzzetti, Fausto

2014-05-01

254

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

255

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

256

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

257

Prehispanic agriculture and climate on the Pacific slope of Guatemala  

Science.gov (United States)

The relationship between agriculture and social complexity is a complicated one through both time and space; this is no less true in prehispanic Mesoamerica. Human occupation of the Pacific Coast of Gualtemala prior to Spanish contact was affected by humans' relationship with their physical environment, including the vegetation and climate. I examined multiple lines of evidence, including phytolith, pollen, and settlement data, seeking to detect changes within the paleoenviromental, paleoclimatic, and socio-cultural records from the Middle and Late Formative (1000 BC to AD 150) through the Classic (AD 150 to 600) and Post-Classic (ca. AD 1000) periods. This work reveals that social complexity on the Pacific Slope of Gualtemala developed alongside agricultural intensification. More significantly, however, it also reveals that while there was a population "collapse" on the Pacific Slope at the end of the Late Formative period, there was not the correlating drought or decline in agriculture seen in other areas of the Maya homeland.

Connolly, Elizabeth Wilcut

258

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.

259

Hydraulic Characteristics of a Stepped-slope Floating Breakwater  

Science.gov (United States)

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.

Teh, H. M.; Ismail, H.

2013-06-01

260

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)

 
 
 
 
261

Assessment of slope stability using PS-InSAR technique  

Science.gov (United States)

In this research work, PS-InSAR approach is envisaged to monitor slope stability of landslides prone areas in Nainital and Tehri region of Uttarakhand, India. For the proposed work, Stanford Method for Persistent Scatterers (StaMPS) based PS-InSAR is used for processing ENVISAT ASAR C-Band data stacks of study area which resulted in a time series 1D-Line of Sight (LOS) map of surface displacement. StaMPS efficiently extracted the PS pixels on the unstable slopes in both areas and the time series 1D-LOS displacement map of PS pixels indicates that those areas in Nainital and Tehri region have measurement pixels with maximum displacement away from the satellite of the order of 22 mm/year and 17.6 mm/year respectively

Dwivedi, R.; Varshney, P.; Tiwari, A.; Singh, A. K.; Dikshit, O.

2014-11-01

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

Bioengineering case studies sustainable stream bank and slope stabilization  

CERN Document Server

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

264

Seismic stability of slopes in sensitive cohesive soils  

Science.gov (United States)

An investigation has been conducted to gain a better understanding of the seismic stability of slopes in sensitive cohesive soils, the undrained shear strength mobilized in earthquake-related slope failures, undrained peak and residual shear strengths of cohesive soils, and the seismic evaluation and/or design of slopes in sensitive cohesive soils. Field case histories were used to show that the undrained peak and residual shear strengths are applicable to the seismic stability of slopes in sensitive cohesive soils. To investigate the undrained peak and residual shear strengths, a Bromhead ring shear apparatus was modified to conduct constant volume/undrained tests. The undrained peak shear strength measured using the constant volume ring shear apparatus compared favorably with the undrained peak shear strength measured in the direct simple shear apparatus on the same material. The constant volume ring shear apparatus was used to measure the undrained peak and residual shear strengths of the soft Bootlegger Cove clay involved in the Fourth Avenue landslide. Back analysis of the Fourth Avenue landslide was conducted to determine the mobilized undrained shear strength that corresponds to the displacements observed during the earthquake. Comparison of measured undrained shear strengths in the constant volume ring shear apparatus and back-calculated values lead to the development of recommendations for the field ground displacement necessary to develop a post-peak and undrained residual condition. The use of the field vane shear test for measuring the undrained peak and residual shear strength was also reviewed. A correction factor for use of the vane shear strengths in seismic stability evaluations was proposed. The validity of the proposed correction factor was verified using the Fourth Avenue, L-Street, Sainte-Thecle, and Saint-Adelphe earthquake induced landslides.

Contreras-Quintero, Ivan Andelfo

1997-08-01

265

Experiment study on overtopping of sloping breakwater by swell  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Along with global climate changing, the disaster caused by overtopping from breakwater or revetment seems further serious. There are many factors which related with wave overtopping flux, one is wave period, some researches have big gap on it. Three formulas of overtopping flux were compared on wave period influence. Eight sections of single sloping breakwater without super structure were tested in wave flume. The overtopping was measured under different wave periods. The measured values w...

Bao, C. H.; Wu, Z. H.; Zai, G. L.; Ping, L. L.

2013-01-01

266

Coal database for Cook Inlet and North Slope, Alaska  

Science.gov (United States)

This database is a compilation of published and nonconfidential unpublished coal data from Alaska. Although coal occurs in isolated areas throughout Alaska, this study includes data only from the Cook Inlet and North Slope areas. The data include entries from and interpretations of oil and gas well logs, coal-core geophysical logs (such as density, gamma, and resistivity), seismic shot hole lithology descriptions, measured coal sections, and isolated coal outcrops.

Stricker, Gary D.; Spear, Brianne D.; Sprowl, Jennifer M.; Dietrich, John D.; McCauley, Michael I.; Kinney, Scott A.

2011-01-01

267

Laboratory study of turbulent gravity currents on a continental slope  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study characterizes the dynamics of a turbulent gravity current flowing down a uniform slope in a rotating media. These dense overflows are of particular interest in oceanography since it is an important mechanism in renewing deep water as part of the global thermohaline convective cycle. The large Coriolis turntable (LEGI) is used to study at the laboratory scale, a gravity current in similarity with the oceanic scales.The propagation of such currents is strongly influenced by rot...

De?camp, Sabine

2005-01-01

268

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

269

Downward-sloping term structure of lease rates: a puzzle  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A model of the term structure of lease rates in a frictionless economy is developed and its predictions are compared with data on residential leases in Japan. The model shows that the initial lease rate for a cancellable lease must be set higher than that for a non-cancellable lease because the former rate will be repeatedly adjusted downward when the market rent decreases. More importantly, the term structure of lease rates is always upward-sloping for cancellable leases. Empirical findings ...

Seko, Miki; Sumita, Kazuto; Yoshida, Jiro

2012-01-01

270

Wood-soil interactions in soil bioengineering slope stabilization works  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Mc, Moscatelli; Romagnoli M; Cenfi S; Lagomarsino A; Di Tizio A; Spina S; Grego S

2009-01-01

271

Ski skating technique and physiological responses across slopes and speeds.  

Science.gov (United States)

Appropriate technique choice may affect ski performance. V2 ski skating technique has in recent years become more widely applied on uphill terrain where V1 technique has typically been used. This investigation compared physiological responses of skiers using V1 and V2 techniques during uphill treadmill roller-skiing. Part 1: six skiers from B-level national ski teams participated in technique comparisons performed under six uphill conditions (3, 4, 5, 6, 7, and 8 degrees) with speeds selected so external work was approximately constant for each slope. The 12 trials of 5-min steady-state skating were randomly distributed across two test sessions of six trials each. Heart rate (HR), oxygen consumption (VO(2)), blood lactate concentration (La) and rating of perceived exertion (RPE) were measured. Part 2: 15 skiers from A-level and B-level national ski teams participated in V1-V2 technique comparison on constant slope (5 degrees) with five speeds ranging from 2.25 to 3.25 m s(-1). In two test sessions of V1 or V2 skating (randomly assigned for 2 days) similar characteristics as Part 1 were measured. Across all variables consistent responses were observed for both the experimental parts. As slope increased, V2 skating became increasingly costly compared to V1 skating. At constant slope across the range of speeds, V2 was more costly than V1 skating. This suggests that it may be disadvantageous for skiers to use V2 instead of V1 skating technique on moderate to steep uphill terrain. Doing so may result in elevated HR, La, and VO(2) compared to V1 skating at the same speed. PMID:16003540

Kvamme, Bent; Jakobsen, Vidar; Hetland, Svein; Smith, Gerald

2005-10-01

272

Influence of strata stress state on openpit mine slope stability  

Energy Technology Data Exchange (ETDEWEB)

The influence of strata stress state on openpit slope stability was investigated. The rock mass stress, defined by the horizontal and vertical components of primary stress, is considered as a rock massif property equal to physico-mechanical and deformation properties. Results of in-situ stress measurements indicate the occurrence of variable relations between primary stress components in dependence with the ground geological history, and such variations may be the cause of landslides in some mine parts. (In Serbo-Croat)

Milanovic, P.

1980-01-01

273

AMS radiocarbon dating on Campos Basin, Southeast Brazilian Continental Slope  

International Nuclear Information System (INIS)

We present results on radiocarbon dating of foraminifera shell samples, collected on the upper slope of Campos Basin, in Southern Brazil. This is the first time that the sedimentation rate of this area is measured with a fine scale (cm) stratigraphy. 14C ages vary from (2560 ± 80) years. BP at the top to (7260 ± 80) years. BP at the bottom of the sediment column. The mean accumulation ratio for the whole column is (6.2 ± 0.7) cm/kyears

274

Exact Slope and Interpolating Functions in ABJM Theory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Using the Quantum Spectral Curve approach we compute exactly an observable (called slope function) in the planar ABJM theory in terms of an unknown interpolating function h(\\lambda) which plays the role of the coupling in any integrability based calculation in this theory. We verified our results with known weak coupling expansion in the gauge theory and with the results of semi-classical string calculations. Quite surprisingly at strong coupling the result is given by an ex...

Gromov, Nikolay; Sizov, Grigory

2014-01-01

275

On the Landslide of Daigala Slope-Kurdistan-Iraq  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The strategic two-lane road (Erbil – Koya) is the main link between Erbil and Suleymaniya governorates. It passes through Daigala bridge whose edge from Koya side is adjacent to a curved section which experienced a slope failure (Fig. 1) in the form of rotational sliding which progressed into a slump failure through the mechanism of “progressive failure” after the overburden soil and sediments were fully saturated with water due to some heavy rain storms which happened at the end of Jan...

Jassim, Assist Prof Dr Hamed M.; Dr. Zahra’a Noori Rasheed; Bahra Dhahir Ghafour; Dr. Faris Rashied Ahmed

2014-01-01

276

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...

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

2011-01-01

277

MOBILE REVERSIBLE BELT CONVEYOR WITH TELESCOPIC CONSTRUCTION AND CHANGEABLE SLOPE  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The diploma work describes development of a mobile transporter for passenger baggage and smaller piece cargo transport on the airplane or in the reverse way. In introduction parts of diploma work there are represented demands of aero travel branch and standards for development of the mobile reversible belt conveyor with telescopic construction and changeable slope. In the main part of diploma we determined belt forces, which work through the bearings of drums into the construction of te...

Otolani, Mirko

2009-01-01

278

Aerial Photogrammetric Analysis of a Scree Slope and Cliff  

Science.gov (United States)

Mapping the physical features of landslide tracks provides information about factors controlling landslide movement. The increasing availability of unmanned aerial vehicles (UAV) provides the opportunity to efficiently and cost effectively map terrain. The main goal of this field study is to create a streamlined work-flow from acquisition to interpretation for the photogrammetric analysis of landslide tracks. Here an open source software package MicMac is used for ortho-image and point-cloud creation. A series of two flights were conducted over a scree (rockfall) slope in Kolsas, Norway. The slope runs roughly 500 m north-south with a maximum width of 60 m. A cliff to the west is the source area for the scree. The cliff consists of conglomerate, basalt, and porphyry from bottom to top respectively. The grain size of boulders in the scree slope apparently varies due to lateral differences in the cliff composition. The flights were completed under cloud cover and consisted of multiple lengthwise passes over the scree field. There was a minimum of 75% overlap between images. During the first flight the altitude was roughly 100 m, the camera was positioned normal to the scree (60 degrees from horizontal), and the resolution was 2.7 cm per pixel. The second flight had an altitude of 200 m, the camera orientation was 30 degrees from horizontal, and the resolution was 4.0 cm per pixel. Using the Micmac engine, Ortho-photos and Digital Elevation Models (DEM) were created for both the scree and the cliff. This data will allow for analysis of grain-size, surface roughness, grain-shape, fracture plane orientation, as well as geological mapping. Further work will focus the quantitative assessment of the significance different camera altitudes and angles have on the results. The work-flow used in this study provides a repeatable method for aerial photogrammetric surveys of scree slopes.

Saunders, Greg; Galland, Olivier; Mair, Karen

2014-05-01

279

Carbonate characteristics of waters of the Arctic Ocean continental slope  

Science.gov (United States)

Carbonate characteristics of the water mass of the deepwater part of the Arctic Ocean (AO) in the continental slope area were determined, and the range and reasons of their variability during summer-fall season were revealed. The AO water area is a meaningful sink for atmospheric carbon dioxide. The warm intermediate Atlantic waters (AW) are also undersaturated with carbon dioxide relative to its content in the atmosphere. While these waters move along AO continental slope, the value pCO2 in the AW core decreases to 8-10 ?atm (mainly, due to drop in the water temperature). The potential absorption capacity of the AO deepwater basin is estimated at approximately 48 Tg of carbon (without sea ice taken into account). Joint analysis of carbonate and hydrological parameters showed that near-bottom waters formed on the shallow shelf of the Laptev Sea, which is rich in inorganic and organic carbon of terrestrial and marine genesis, take part in formation of halocline waters of the AO. They are modified due to interaction with AW penetrating to the shelf and are transferred to the deepwater AO segment, where they occur in the halocline according to their density. Transformed near-bottom waters of the Laptev Sea shelf, similar to waters of the halocline of Pacific origin in the eastern sector of the AO, are traced above the continental slope in Amundsen Basin on the basis of higher CO2 concentrations.

Pipko, I. I.; Pugach, S. P.; Semiletov, I. P.; Salyuk, A. N.

2011-06-01

280

Characterization and calibration of 2nd generation slope measuring profiler  

Science.gov (United States)

High spectral resolution and nanometer sized foci of 3rd generation SR beamlines can only be achieved by means of ultra precise optical elements. The improved brilliance and the coherence of free electron lasers (FEL) even push the accuracy limits and make the development of a new generation of ultra precise reflective optical elements mandatory. Typical elements are wave front preserving plane mirrors (lengths of up to 1 m, residual slope errors ˜0.05 ?rad (rms) and values of 0.1 nm (rms) for the micro-roughness) and curved optical elements like spheres, toroids or elliptical cylinder (residual slope error ˜0.25 ?rad (rms) and better). These challenging specifications and the ongoing progress in finishing technology need to be matched by improved accuracy metrology instruments. We will discuss the results of recent developments in the field of metrology made in the BESSY-II-optics laboratory (BOL) at the Helmholtz Zentrum Berlin (HZB), by the use of vertical angle comparator (VAC) in use to calibrate the nanometer optical component measuring machine (NOM). The BESSY-NOM represents an ultra accurate type of slope measuring instruments characterized by an accuracy of 0.05 ?rad (rms) for plane substrates and 0.2 ?rad (rms) for significant curved surfaces.

Siewert, Frank; Buchheim, Jana; Zeschke, Thomas

2010-05-01

 
 
 
 
281

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

282

DEVELOPMENT OF SHALLOW VISCOUS OIL RESERVES IN NORTH SLOPE  

Energy Technology Data Exchange (ETDEWEB)

North Slope of Alaska has huge oil deposits in heavy oil reservoirs such as Ugnu, West Sak and Shrader Bluff etc. The viscosity of the last two reservoir oils vary from {approx}30 cp to {approx}3000 cp and the amount in the range of 10-20 billion barrels. High oil viscosity and low formation strength impose problems to high recovery and well productivity. Water-alternate-gas injection processes can be effective for the lower viscosity end of these deposits in West Sak and Shrader Bluff. Several gas streams are available in the North Slope containing NGL and CO{sub 2} (a greenhouse gas). The goal of this research is to develop tools to find optimum solvent, injection schedule and well-architecture for a WAG process in North Slope shallow sand viscous oil reservoirs. In the last quarter, we have developed streamline generation and convection subroutines for miscible gas injection. The WAG injection algorithms are being developed. We formulated a four-phase relative permeability model based on two-phase relative permeabilities. The new relative permeability formulations are being incorporated into the simulator. Wettabilities and relative permeabilities are being measured. Plans for the next quarter includes modeling of WAG injection in streamline based simulation, relative permeability studies with cores, incorporation of complex well-architecture.

Kishore K. Mohanty

2003-07-01

283

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

284

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.

285

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

286

Presidendipaar võõrustas Ärma talus Poola presidenti abikaasaga  

Index Scriptorium Estoniae

Poola presidendi Lech Kaczynski ja tema abikaasa Maria Kaczynska ühepäevasest töövisiidist Eestisse. President Toomas Hendrik Ilves ja proua Evelin Ilves tutvustasid külalistele Ärma talukompleksi. Presidentidel oli ka tööjutuajamine mõlemat riiki huvitavatel teemadel

2008-01-01

287

Performance of the Bowen ratio systems on a 22 deg slope  

Science.gov (United States)

The Bowen ratio energy balance technique was used to assess the energy fluxes on inclined surfaces during the First ISLSCP Field Experiment (FIFE). Since air flow over sloping surface may differ from that over flat terrain, it is important to examine whether Bowen ratio measurements taken on sloping surfaces are valid. In this study, the suitability of using the Bowen ratio technique on sloping surfaces was tested by examining the assumptions that the technique requires for valid measurements. This was accomplished by studying the variation of Bowen ratio measurements along a selected slope at the FIFE site. In September 1988, four Bowen ratio systems were set up in a line along the 22 degree north-facing slope with northerly air flow (wind went up the slope). In July of 1989, six Bowen ratio systems were similarly installed with southerly air flow (the wind went down slope). Results indicated that, at distances between 10 to 40 meters from the top of the slope, no temperature or vapor pressure gradient parallel to the slope was detected. Uniform Bowen ratio values were obtained on the slope, and thus the sensible or latent heat flux should be similar along the slope. This indicates that the assumptions for valid flux measurements are reasonably met at the slope. The Bowen ratio technique should give the best estimates of the energy fluxes on slopes similar to that in this study.

Nie, D.; Flitcroft, I.; Kanemasu, E. T.

1990-01-01

288

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

289

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 staluate 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

290

Microseismic Monitoring of Induced Slope Failures at Field Scale  

Science.gov (United States)

A number of published studies use seismic sensors to identify and locate precursory landslide signals and slope failures. In this research we artificially induced failure to two, meter scaled, slopes in the field. To our knowledge there has been no previous controlled experiments that can allow calibration and validation of the interpreted seismic signals. The aim of this study was to investigate whether low-cost seismic monitoring can capture the emitted seismic waves and distinguish between different landslide failure phases (pre-, during and post-failure). The experimental site was located in Brasilia (Brazil). Two vertical artificial faces, approximately 2m high, were excavated 3m apart in high porous tropical clay. This material is highly attenuative making the detection of weak seismic signals challenging. A hydraulic jack was used to apply an increasing vertical load through a metallic plate to the soil's surface causing failure of the slope. Both experiments took place during night when the ambient noise was at minimum levels. The failure process of both faces was monitored using 12 short period 3D seismometers of frequency range 2-100Hz. All sensors were placed on the ground surface before the crown of the vertical faces, and one sensor at their toe. The deployment geometry created a dense microseismic network with approximately 10m spacing between the sensors and two nanoseismic arrays, with aperture sizes of 10 and 20 m, respectively. The two faces failed in a different way despite the identical geological and loading conditions. This provided an excellent opportunity to monitor signals of different amplitude and waveform. The first face failed as two vertical slides 2m high, on each side of the metallic plate, at a vertical load of 80-90kN. Only small failures at the crown of the slope were observed for the second face. These happened at a load of 70 and 100kN. Our analysis, based on signal processing techniques, allowed for the amplification of failure signals above noise level and therefore the identification, and location of the sources of the failure signals even in a high attenuation medium such as the tropical clay. Results were groundproofed by visual observations. Our study shows that microseismic monitoring can be used to monitor weak ground failures and provide information on the failure mechanism of slopes, a powerful tool for geotechnical engineering applications.

Yfantis, Georgios; Martinez Carvajal, Hernan Eduardo; Pytharouli, Stella; Lunn, Rebecca

2013-04-01

291

Asymmetric craters on Vesta: Impact on sloping surfaces  

Science.gov (United States)

Cratering processes on planetary bodies happen continuously and cause the formation of a large variety of impact crater morphologies. On Vesta whose surface has been imaged at high resolution during a 14 months orbital mission by the Dawn spacecraft we identified a substantial number of craters with an asymmetrical shape. These craters, in total a number of 2892 ranging in diameter from 0.3 km to 43 km, are characterized by a sharp crater rim on the uphill side and a smooth one on the downhill side. The formation of these unusual asymmetric impact craters is controlled by Vesta's remarkable topographic relief. In order to understand the processes creating such unusual crater forms on a planetary body with a topography like Vesta we carried out the following work packages: (1) the asymmetric craters show various morphologies and therefore can be subdivided into distinct classes by their specific morphologic details; (2) using a digital terrain model (DTM), the craters are grouped into bins of slope angles for further statistical analysis; (3) for a subset of these asymmetric craters, the size-frequency distributions of smaller craters superimposed on their crater floors and continuous ejecta are measured in order to derive cratering model ages for the selected craters and to constrain possible post-impact processes; (4) three-dimensional hydrocode simulations using the iSALE-3D code are applied to the data set in order to quantify the effects of topography on crater shape and ejecta distribution. We identified five different classes (A-E) of asymmetric craters. Primarily, we focus on class A in this work. The global occurrence of these crater classes compared with a slope map clearly shows that these asymmetric crater types exclusively form on slopes. We found that slopes, especially slopes >20°, prevent the deposition of ejected material in the uphill direction, and slumping material superimposed the deposit of ejecta on the downhill side. The combination of these two processes explains the local accumulation of material in this direction. In the subset of asymmetric craters which we used for crater counts, our results show that no post-impact processes have taken place since floors and continuous ejecta in each crater show comparable cratering model ages within the uncertainties of the cratering chronology model. Therefore the formation, or modification, of the asymmetric crater forms by processes other than impact can be excluded with some certainty.

Krohn, K.; Jaumann, R.; Elbeshausen, D.; Kneissl, T.; Schmedemann, N.; Wagner, R.; Voigt, J.; Otto, K.; Matz, K. D.; Preusker, F.; Roatsch, T.; Stephan, K.; Raymond, C. A.; Russell, C. T.

2014-11-01

292

Bird diversity and land use on the slopes Bird diversity and land use on the slopes, Tanzania  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study of bird distribution in the main land-use categories of the slopes of Mt Kilimanjaro,Tanzania, aims at understanding potential impacts of the land-use changes on birds. A land-use map of the study area was derived from a Landsat image, and land-use change information came from an earlier study by the author. Bird data were collected by o...

Eija Soini

2011-01-01

293

The Socioeconomic Assessment of Sloping Land Conversion Program in China  

DEFF Research Database (Denmark)

Abstract This thesis mainly focuses on the socioeconomic impact of the largest Ecological Recovery Program ? the Sloping Land Conversion Program (SLCP), also called Grain for Green Program (GFG) in China. The central government initiated this program in 1999 and it was launched nationwide in 2002 with the aim to combat deforestation, ecological degradation, over cultivation of sloping land and soil erosion. However, we also believe it brings changes to the rural economic structure and household livelihood strategy. Applying and developing some empirical and theoretical methods with a large amount of household survey data, this study aims to improve our understanding of the treatment effect of the SLCP on farm households, which is split into three parts. The first paper ? The Sloping Land Conversion Program in China: Effects on Rural Households’ Livelihood Diversification, evaluates the effects of the implementation of the Sloping Land Conversion Program (SLCP) on livelihood diversification, which is thought to be the solution to poverty and environmental dilemmas. Our results show that SLCP works as a valid external policy intervention on rural livelihood diversification. In addition, the findings suggest that there exist heterogeneous effects of SLCP implementation on livelihood diversification across different rural income groups. The lower income group was more affected by the program in terms of income diversification. The Second paper ? The Effects of Sloping Land Conversion Program on Agricultural Households, analyzes whether the program influences farm household behaviour in the form of production, consumption and labor supply. In doing so, we first develop a microeconomic Agricultural Household Model (AHM), which can model the production, consumption, and labor supply decisions of farm households in rural China in a theoretically consistent fashion. Based on this theoretical model, we derive an empirical specification for econometrically estimating the effects of the SLCP and other exogenous factors. Using a large longitudinal farm household survey data set, we estimate the empirical model with the Hausman-Taylor Estimator method. The key results regarding the households’ responses to the program nicely coincide with the results of our theoretical comparative static analysis, i.e. the SLCP decreases agricultural production and increases non-farm labor supply and consumption. In addition, on average, reduction of compensation payment rate lowers the treatment effect of the SLCP on participating households from both River basins. Lastly, the third paper, ? The effect of the Sloping Land Conversion Program on farm household productivity in rural China, investigates the treatment effect (the causal effect) of the Sloping Land Conversion Program (SLCP) on farm household productivity. Using the same survey data set as the above two papers, I apply the nonparametric Malmquist index method to estimate the change in farm household productivity. In connection with evaluating the treatment effects, propensity score matching, which can give a randomized evaluation, is employed in a second stage. The main results show that the SLCP significantly improved the productivity of participants in the first funding period which are mostly from efficiency improvements, while the effects decreased in the second round except the positive impact in 2007. Moreover, it is found that there are heterogeneous effects on farm household productivity between the south and north, as well as poor and rich region. In sum, the findings from this thesis highlight that SLCP has significant effects on the farm household in different ways, most of which support the policy intention of central government according to our own understanding, whereas the effects differ depending on the group, region and period. This research provides a detailed understanding of the treatment effects of the SLCP and thus, contributes to the on-going political debate about the revision of the SLCP and also to the scientific knowledge about the effect evaluation of

Liu, Zhen

2014-01-01

294

50 CFR Table 27 to Part 679 - Gulf of Alaska Slope Habitat Conservation Areas  

Science.gov (United States)

...false Gulf of Alaska Slope Habitat Conservation Areas...EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 679, Table 27...to Part 679—Gulf of Alaska Slope Habitat Conservation Areas...Projected coordinate system is North American Datum...

2010-10-01

295

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

296

The Contribution of Particle Swarm Optimization to Three-Dimensional Slope Stability Analysis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D) slope stability analysis. This paper applied PSO in three-dimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this techniqu...

Roohollah Kalatehjari; Rashid, Ahmad Safuan A.; Nazri Ali; Mohsen Hajihassani

2014-01-01

297

Temporal characteristics of different cryosphere-related slope movements in high mountains  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Knowledge of processes and factors affecting slope instability is essential for detecting and monitoring potentially hazardous slopes. The overall aim of this study is to detect and characterize different slope movements in alpine periglacial environments, with the ultimate goal to understand the broad range of phenomena and processes encountered. In this article, a potential strategy for analyzing the spatio-temporal (seasonal and intra-annual) velocity fluctuations of various slope movement...

Wirz, Vanessa; Beutel, Jan; Buchli, Bernhard; Gruber, Stephan; Limpach, Philippe

2011-01-01

298

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

299

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

 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. 

??????????, ?. ?. ???; ???????????, ?. ?. ???

2006-01-01

300

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

 
 
 
 
301

Classification and hydrological characteristics of scree slope deposits in the northern Craigieburn Range, New Zealand.  

Science.gov (United States)

Slope deposits occurring beneath the surface layer of loose angular gravel on north Craigieburn Range scree slopes can be subdivided into three significantly different types. The wide range in physical characteristics of the slope deposits is mirrored by an equally wide range in hydrological characteristics. -from Author

Pierson, T.C.

1982-01-01

302

The operation and slope maintenance of deep, extensive surface mines in close proximity to urban districts  

Energy Technology Data Exchange (ETDEWEB)

Using Fushun Surface Mine as example, this paper investigates the slope movement and large scale collapse of slopes in deep and extensive surface mines in Jinlin mining district. The problem of slope stability and the safety of surrounding rocks, as well as the control of further deformation are discussed. The programme for tackling this problem is briefly described.

Rui, Y.; Zhang, S.; Jiang, Z. [Central Coal Research Institute (China). Fushun Branch

1996-03-01

303

75 FR 56562 - Proposed Information Collection Request Submitted for Public Comment and Recommendations; Slope...  

Science.gov (United States)

...of workmen in each slope or shaft that is commenced or extended...underground coal mine. Each slope or shaft sinking operation is unique...which make it impossible for a single set of regulations to assure...makes an individual slope or shaft sinking plan necessary....

2010-09-16

304

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

305

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

306

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

307

Conservation laws for shallow water waves on a sloping beach  

Directory of Open Access Journals (Sweden)

Full Text Available Shallow water waves are governed by a pair of non-linear partial differential equations. We transfer the associated homogeneous and non-homogeneous systems, (corresponding to constant and sloping depth, respectively, to the hodograph plane where we find all the non-simple wave solutions and construct infinitely many polynomial conservation laws. We also establish correspondence between conservation laws and hodograph solutions as well as Bäcklund transformations by using the linear nature of the problems on the hodogrpah plane.

Yilmaz Akyildiz

1986-06-01

308

Slope effect on stability of stratified two-phase flow  

Science.gov (United States)

The modeling of transient liquid/gas interface in a two-phase stratified flow through a horizontal or nearly-horizontal circular duct has been investigated. A one-dimensional two-fluid model for horizontal flows, based on a set of non linear hyperbolic governing equations, was considered. Each phase is characterized by its equations of conservation written in dimensionless form. The method of characteristics combined with an explicit method is used to simulate the flow. The model accounts for the pipe inclination effects. It is shown that, an upward inclination leads to a more probable slug flow, whereas negative values of the slope induce a more stable stratified flow.

Salhi, Yacine; Si Ahmed, E. K.; Degrez, G.; Legrand, Jack

2010-03-01

309

Zonal slope prediction for open-loop adaptive optics.  

Science.gov (United States)

We present what we believe to be the first results that obtained with the recursive least square zonal slope predictor working on an open-loop liquid-crystal adaptive optics system operating on astronomical implementation at visible and near infrared wavelength on a 1.23 m telescope. The system produces substantially better results than a direct open-loop correction based on previous measurement. A 27% relative gain in full-width at half-maximum and 30% relative gain in Strehl ratio are obtained. PMID:22089597

Liu, Chao; Hu, Lifa; Cao, Zhaoliang; Mu, Quanquan; Xuan, Li

2011-11-15

310

Contrast Analysis on Fractional Order and Slope Correlation Accuracy  

Directory of Open Access Journals (Sweden)

Full Text Available In order to improve the correlation accuracy of correlation algorithm, the fractional order correlation algorithm of  uncertain time sequences is proposed in this paper. By taking advantage of the memory property of fractional order, the algorithm introduces the measurement of fractional order differential for the local trend of time sequence into the correlation algorithm and also analyzes the influences of differential order and noise upon correlation accuracy, provides selection relations between noise level and order. It has been proven with examples that the correlation accuracy of fractional order correlation algorithm has increased by one orders of magnitude as compared with slope correlation.

Mingliang Hou

2012-08-01

311

Effluent Discharges from Two Outfalls on a Sloping Beach  

Directory of Open Access Journals (Sweden)

Full Text Available A marine outfall is a long pipeline that continuously discharges large amounts of effluent streams into the sea. As the number of marine outfalls along the coastal areas is growing, a far field mathematical model with two point sources on a sloping beach is used to assess the coastal water quality following discharges from two outfalls. Asymptotic approximation will be made to the concentration at the beach to measure how well the effluent plumes are mixed and diluted in the coastal waters. The result found agrees with the engineering practice of installing a two-port diffuser at the end of a single outfall to minimize its potential environment impacts.

Anton Purnama

2014-11-01

312

Sediment dispersal and accumulation in tectonic accommodation across the Gaoping Slope, offshore Southwestern Taiwan  

Science.gov (United States)

Distribution and architecture of slope basins across a continental slope vary as a consequence of accommodation forming, sediment dispersal rates, canyon cutting, sediment filling and different sediment transporting mechanisms. The area offshore Southwestern Taiwan is generally recognized as having active tectonics and high sediment deposition rates. In the Gaoping Slope, slope basins are formed by the developments of folds, faults and diapiric intrusions. Portions of the sediments discharged from the Taiwan mountain belt have been trapped in these basins in the Gaoping Shelf and Gaoping Slope. The rest of the sediments were transported to deep sea areas through submarine canyons. This complex system of folds, faults, diapirs, slope basins, submarine canyons, and sediment deposits has also readjusted the morphology of the Gaoping Slope. This study examines the linkage between accommodation spaces of tectonic and sedimentary processes in the Gaoping Slope through seismic facies analysis. Four seismic facies which include convergent-symmetrical facies, convergent-baselapping facies, chaotic facies, and parallel and drape facies, and different deposition patterns have been recognized in the Gaoping Slope basins. The thick mud layers which are regarded as the source of diapiric intrusions are first observed beneath the basin. Strata records show that the accommodation spaces in various slope basins have increased or decreased during different stages of basin evolution. Because of the competition between regional tectonism (accommodation space variations) and sediment routing distance from provenance to depository (sediment input variations), most under-filled basins lie in the lower slope domain in the Gaoping Slope, but also in the upper slope domain east of the Gaoping Submarine Canyon. This observation suggests that in the inner Gaoping Slope west of the Gaoping Submarine Canyon, sediment deposition rate is higher than the basin subsidence rate, the topography of the upper slope domain there is "healed", and most sediments are overfilled in the slope basins now. Besides the sequential steps of sedimentary disposal in the filling-and-spilling model, we have also observed evidences which indicate that mass movements and submarine canyons in the area have significantly changed the sediment dispersal patterns in the slope basins of the Gaoping Slope. We suggest that although filling-and-spilling is a key sedimentary process in the Gaoping Slope, tectonic activities, mass wasting events and canyon feeding processes have diversified sediment transporting mechanisms from the inner to outer slopes in the area offshore Southwest Taiwan.

Hsu, Ho-Han; Liu, Char-Shine; Yu, Ho-Shing; Chang, Jih-Hsin; Chen, Song-Chuen

2013-06-01

313

Effects of equipment loadings on geosynthetic-lined slope behaviour.  

Science.gov (United States)

When combined in the lining and covering of waste-containment facilities, soil and geosynthetic components protect the environment by acting as a hydraulic barrier. Equipment loading may significantly increase the tensile stress induced in geosynthetic components, leading to a potential stability problem. Large equipment loadings may also result in a localized circular slip surface during construction operations. New analytical method based on discrete element modelling is proposed for estimating the distribution of tensile force developed in the individual geosynthetic components of the lining system and for evaluating the safety factor of slope failure due to equipment loading. The analytical results of an example are presented to demonstrate the applicability of the analytical method for the lining system of a waste landfill. The analyses of the example show that equipment loading provide a substantial increase in the tensile forces of the geosynthetic components of a lining system and that the possibility of shallow failure due to equipment loading increases as the slope becomes steeper. This method is a useful tool for analysing the lining system of waste landfills with complex lining components. PMID:15988943

Park, Hyun I; Lee, Seung R

2005-06-01

314

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

315

Fast and accurate estimation of solar irradiance on Martian slopes  

Science.gov (United States)

A general parameterization is proposed in this study to calculate, in a Mars-like dusty atmosphere, the solar irradiance reaching an inclined surface, assuming the value in the horizontal case is known. Complete Monte-Carlo radiative transfer calculations, using the Ockert-Bell et al. (1997) dust optical properties, enable the validation of the method for Mars. The total shortwave flux reaching the surface is composed of three contributions: direct incoming flux, reflected flux by surrounding terrains, and scattered flux by the atmospheric dust. The main difficulty is the parameterization of the latter component. We show that the scattered flux reaching the slope can be expressed by a physically-based simple formula involving one empirical coupling matrix and two vectors accounting for the scattering properties and the geometrical settings. The final result is a computationally efficient parameterization, with an accuracy in most cases better than 5 W.m-2. Such a fast and accurate method to calculate solar irradiance on Martian slopes (should they be topographical surfaces or solar panels) is of particular interest in a wide range of applications, such as remote-sensing measurements, geological and meteorological models, and Mars exploration missions design.

Spiga, Aymeric; Forget, François

2008-08-01

316

Spectral Slope as an Indicator of Pasture Quality  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, we develop a spectral method for assessment of pasture quality based only on the spectral information obtained with a small number of wavelengths. First, differences in spectral behavior were identified across the near infrared–shortwave infrared spectral range that were indicative of changes in chemical properties. Then, slopes across different spectral ranges were calculated and correlated with the changes in crude protein (CP, neutral detergent fiber (NDF and metabolic energy concentration (MEC. Finally, partial least squares (PLS regression analysis was applied to identify the optimal spectral ranges for accurate assessment of CP, NDF and MEC. Six spectral domains and a set of slope criteria for real-time evaluation of pasture quality were suggested. The evaluation of three level categories (low, medium, high for these three parameters showed a success rate of: 73%–96% for CP, 72%–87% for NDF and 60%–85% for MEC. Moreover, only one spectral range, 1748–1764 nm, was needed to provide a good estimation of CP, NDF and MEC. Importantly, five of the six selected spectral regions were not affected by water absorbance. With some modifications, this rationale can be applied to further analyses of pasture quality from airborne sensors.

Rachel Lugassi

2014-12-01

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

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

319

On the Landslide of Daigala Slope-Kurdistan-Iraq  

Directory of Open Access Journals (Sweden)

Full Text Available The strategic two-lane road (Erbil – Koya is the main link between Erbil and Suleymaniya governorates. It passes through Daigala bridge whose edge from Koya side is adjacent to a curved section which experienced a slope failure (Fig. 1 in the form of rotational sliding which progressed into a slump failure through the mechanism of “progressive failure” after the overburden soil and sediments were fully saturated with water due to some heavy rain storms which happened at the end of January 2013 leading to the loss of cohesive force and triggering that failure which was developed into a progressive failure by the action of additional loading which was imposed by the heavy traffic of big oil tankers which were running on the adjacent paved road. The research team tried to study and analyze this failure by collecting some soil samples (both disturbed and disturbed from the study area and performing different laboratory tests in addition to some in-situ field tests by using the “Inspection Vane Tester, H – 60” for the purpose of enabling this study and analysis. The location of the study area was described and illustrated by providing a location map and the geological settings were explained. As a theoretical background, the different modes of soil slopes failures and their conditions were presented. At the end, some conclusions of this study were outlined and few recommendations for future remedial measures were eventually made.

Assist. Prof. Dr. Hamed M. Jassim

2014-06-01

320

The anatomical basis for the sloping N2 plateau.  

Science.gov (United States)

We examined the influence of asymmetry on the interaction of convection and gas-phase diffusion within the acinus of the lung. Single breaths of O2 were simulated by solving a differential equation for gas transport in two trumpet shaped units which were joined at a branch point and whose relative lengths and volumes were made to vary. Despite synchronous bulk flow to the from the units, in proportion to their relative volumes, the shorter unit always reached a higher O2 concentration (FO2) at end inspiration. Interdependence of gas transport at the branch point resulted in a falling FO2 within the shorter unit during expiration. The FO2 at the exit of the model therefore decreased progressively throughout expiration, simulating a sloping alveolar plateau. The simulations suggest that despite the relatively short distances separating parallel intra-acinar pathways, convective-diffusive interactions in the presence of asymmetry may produce substantial inhomogeneity in alveolar gas concentrations. Furthermore, the slope of the N2 plateau in the normal mammalian lung is explicable on the basis of the asymmetrical airway anatomy and well defined physical processes. PMID:7268221

Paiva, M; Engel, L A

1981-06-01

 
 
 
 
321

A Simple Statistic for Comparing Moderation of Slopes and Correlations  

Science.gov (United States)

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 variance in Y, and a test for this ratio has not been investigated. Given that regression coefficients are proportional to ? 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. PMID:22866042

Smithson, Michael

2012-01-01

322

Stability Analysis for Loosened Rock Slope of Jinyang Grand Buddha in Taiyuan, China  

Science.gov (United States)

On the basis of the status quo of Jinyang Grand Buddha in Taiyuan, some factors such as topography, geological structures, climate, hydrology, and engineering geology that influence the stability of the Buddha slope are considered, and several working situations of the slope that possibly suffered are presented in this article. The Buddha slope stands upright and the rock masses are composed of thick Permian sandstone, which dips slightly inward to the slope. Affected by both the incision of regional joints and the load relief to the free surface, the rock mass of the Buddha slope has turned into loosened blocks. Numerical stability analysis by FLAC-2D on the basis of the strength reduction method reveals that the localized deformation of the rock masses near the vertical surface of the slope may trigger reversing of rock beddings making the back dip slope convert into a dip slope with the possibility of plane sliding failure. Furthermore, the pseudostatic method for the dynamic process and limit equilibrium method for the static process are applied to different working situations of the Buddha slope. The analytical results illustrate that plane sliding failure will not occur when the slope is affected only by seism. However, water filling in the cracks of the loosened rock mass may greatly contribute to the potential plane sliding failure. When horizontal seism-force and hydrostatic pressure are coupled, the Buddha slope can hardly keep stable. Additionally, the loosened rock masses are prone to block toppling failure when influenced by the seism force.

SUN, Jinzhong; TIAN, Xiaofu; GUAN, Xudong; YU, Yonggui; YANG, Xiusheng

323

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

324

Thresholds for the slope ratio in determining transition time and quantifying diffuser performance in situ.  

Science.gov (United States)

This study is concerned with an objective measure called the slope ratio that can detect acoustic defects due to unexpected pressure increases such as strong reflections and coincidental constructive interference. The slope ratio is the ratio of the instantaneous slope to the mean slope in a decay curve. The slope ratio was suggested for determining the room acoustic transition time experimentally, but its threshold criteria have not been thoroughly investigated. The thresholds for the slope ratio, particularly for applications such as determining the room acoustic transition time and quantifying in situ diffuseness, are examined for various room impulse responses. For the tested rooms, a slope ratio threshold of 11 gives the most consistent and systematic results. PMID:22978872

Jeong, Cheol-Ho; Jacobsen, Finn; Brunskog, Jonas

2012-09-01

325

Thresholds for the slope ratio in determining transition time and quantifying diffuser performance in situ  

DEFF Research Database (Denmark)

This study is concerned with an objective measure called the slope ratio that can detect acoustic defects due to unexpected pressure increases such as strong reflections and coincidental constructive interference. The slope ratio is the ratio of the instantaneous slope to the mean slope in a decay curve. The slope ratio was suggested for determining the room acoustic transition time experimentally, but its threshold criteria have not been thoroughly investigated. The thresholds for the slope ratio, particularly for applications such as determining the room acoustic transition time and quantifying in situ diffuseness, are examined for various room impulse responses. For the tested rooms, a slope ratio threshold of 11 gives the most consistent and systematic results.

Jeong, Cheol-Ho; Jacobsen, Finn

2012-01-01

326

Spatial analysis of mutual fault/fracture and slope controls on rocksliding in Darjeeling Himalaya, India  

Science.gov (United States)

In this paper, the Fry analysis was applied to study the spatial patterns (in terms of trends) of rockslides; proportion analysis was applied to study the spatial associations between rockslides and slope aspects; and distance distribution analysis was applied to study the spatial associations of rockslides with different sets of faults/fractures based on trends. In a study area in the Darjeeling district (India), the results of applications of these spatial analytical techniques support a proposition of mutual fault/fracture and slope controls on rocksliding. In different parts of the study area, deep-seated rockslides are associated with (a) NE-trending faults/fractures and SSE-facing slopes, (b) NW-trending faults/fractures and ENE-facing slopes, and (c) NNE-trending faults/fractures and SE- or ENE-facing slopes; whereas shallow translational rockslides are associated with (a) NNE-trending faults/fractures and SE-, NW-, WNW- or WSW-facing slopes, (b) WNW-trending faults/fractures and SW-facing slopes, (c) NNW-trending faults/fractures and ESE- or SW-facing slopes, and (d) NW-trending faults/fractures with SW-facing slopes. Creating and integrating spatial evidence layers representing mutual fault/fracture and slope controls on rocksliding can be achieved satisfactorily via application of evidential belief functions. A predictive map of rockslide susceptibility derived by using slope aspects, slope inclinations and proximity to the faults/fractures that are spatially associated with rockslides is superior to that derives by using slope aspects, slope inclinations and proximity to all faults/fractures. The proposed analytical methods are suitable for first-pass regional-scale assessment of rockslide susceptibility.

Ghosh, Saibal; Carranza, Emmanuel John M.

2010-10-01

327

Primary discussion on the relationship between spatial distributions of fuzzy slope positions and soil types  

Science.gov (United States)

As one of key factors which control the spatial soil variation in soil-landscape model, terrain information includes not only topographic attributes (such as slope gradient, curvature, etc.) but also information of slope positions. But the spatial gradation of slope positions is still not quantitatively considered in current predictive soil mapping and other related application areas. The issue of this paper is to make a primary discussion on the potential role of spatial gradation of slope positions in soil-landscape model. Taking a study area in Northeast China and a detailed taxonomy of slope position, this paper firstly utilized a fuzzy inference approach based on similarity to the typical locations to quantify the spatial gradation between slope positions. Secondly, we took use of the soil-subgroup map in study area to analyze whether there is an evident relationship between soil distribution and spatial gradation of slope positions or not, by means of the statistics on the percentage of slope positions on where each soil subgroup in study area is distributed. The results show that the distributions between slope positions and soil subgroups are clearly correlative in the areas where fuzziness as one certain slope position is little. And the soil distribution shows obvious intergradation and uncertainty in areas where the slope position is identified with much ambiguity. The evident relationship between soil distribution and spatial gradation of slope positions indicates that the quantitative information of spatial gradation of slope positions should be included into both soil-landscape model and its applications (e.g., digital soil mapping, etc.), for a better depiction on the co-variation between slope positions and soil type.

Qin, Cheng-Zhi; Zhu, A.-Xing; Yang, Lin; Li, Bao-Lin; Pei, Tao

2009-10-01

328

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

329

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

330

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

331

The Dynamic Evaluation of Rock Slope Stability Considering the Effects of Microseismic Damage  

Science.gov (United States)

A state-of-the-art microseismic monitoring system has been implemented at the left bank slope of the Jinping first stage hydropower station since June 2009. The main objectives are to ensure slope safety under continuous excavation at the left slope, and, very recently, the safety of the concrete arch dam. The safety of the excavated slope is investigated through the development of fast and accurate real-time event location techniques aimed at assessing the evolution and migration of the seismic activity, as well as through the development of prediction capabilities for rock slope instability. Myriads of seismic events at the slope have been recorded by the microseismic monitoring system. Regions of damaged rock mass have been identified and delineated on the basis of the tempo-spatial distribution analysis of microseismic activity during the periods of excavation and consolidation grouting. However, how to effectively utilize the abundant microseismic data in order to quantify the stability of the slope remains a challenge. In this paper, a rock mass damage evolutional model based on microseismic data is proposed, combined with a 3D finite element method (FEM) model for feedback analysis of the left bank slope stability. The model elements with microseismic damage are interrogated and the deteriorated mechanical parameters determined accordingly. The relationship between microseismic activities induced by rock mass damage during slope instability, strength degradation, and dynamic instability of the slope are explored, and the slope stability is quantitatively evaluated. The results indicate that a constitutive relation considering microseismic damage is concordant with the simulation results and the influence of rock mass damage can be allowed for its feedback analysis of 3D slope stability. In addition, the safety coefficient of the rock slope considering microseismic damage is reduced by a value of 0.11, in comparison to the virgin rock slope model. Our results demonstrate that microseismic activity induced by construction disturbance only slightly affects the stability of the slope. The proposed feedback analysis technique provides a novel method for dynamically assessing rock slope stability and can be used to assess the slope stability of other similar rock slopes.

Xu, N. W.; Dai, F.; Liang, Z. Z.; Zhou, Z.; Sha, C.; Tang, C. A.

2014-03-01

332

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

333

Digital data base of lakes on the North Slope, Alaska  

Science.gov (United States)

The National Mapping Division and Water Resources Division of the U.S. Geological Survey have produced a digital data base of approximately 23,330 lakes on the North Slope of Alaska. The inventoried region consists of the area north of the 69th parallel and is composed of sixteen 1 degree by 3 degree quadrangles. The data base includes (1) locations of lake centers in latitude and longitude, (2) a unique number for each lake within a quadrangle, and (3) acreage for water classes (deep, shallow or turbid, and ice) within each lake and lake total. The digital data base is an easily accessible storage and retrieval system that will allow for rapid identification of a particular lake or region of lakes and its characteristics. The data base is designed to accommodate field study data such as lake depth, water quality, volume of water, ice thickness, and other pertinent information. (Author 's abstract)

Walker, Kim-Marie; York, James; Murphy, Dennis; Sloan, C.E.

1986-01-01

334

Geomorphic processes on the North Slope of Alaska  

Science.gov (United States)

Three physiographic provinces comprise the North Slope of Alaska: the Arctic Mountains, the Arctic Foothills and the Arctic Coastal Plain Provinces. The features and processes in the Arctic Coastal Plain, a zone of continuous permafrost, are stressed in this paper. The evidence for and mechanisms of the geomorphic cycle are discussed starting with frost cracks. Frost cracks may form polygonal ground which leads to low-centered ice wedge polygons in areas having ice-rich permafrost. As the low-centered ice wedge polygons enlarge due to thermal erosion they may evolve into thaw lakes which are largely oriented in a northwest-southeast direction on the Arctic Coastal Plain. Eventual drainage of a deep lake may result in a closed-system pingo. Evidence of the various stages of the geomorphic cycle is ubiquitous on the Alaskan Arctic Coastal Plain and indicates the ice content of the permafrost in some areas.

Hall, D. K.

1979-01-01

335

A method for the development of thick gently sloping layers  

Energy Technology Data Exchange (ETDEWEB)

A method is presented for the development of thick gently sloping coal layers, comprising the laying of conveyor and ventilation paths and the extraction of the layer by underhand facing with the reinforcement of the roof and holding up the latter on the remaining coal blocks left behind in the exhausted space, is characterized in that for the purpose of increasing the effectiveness of the working over and decreasing the volume of the carrying out the prepared developments, the conveyor path is layed for the whole thickness of the layer, and the ventilation path near the roof of the layer, the extraction of coal is carried out in the benches by bands with the angle of advance of the front of the face of the upper bench.

Aladyshev, V.P.; El' chaninov, E.A.; Krylov, V.F.

1980-06-10

336

Energetic plumes over the western Ross Sea continental slope  

Science.gov (United States)

Rapid descent of dense Drygalski Trough (western Ross Sea, Antarctica) shelf water over the continental slope, within 100 to 250 m thick benthic plumes, is described. Speeds of up to 1.0 m/s are recorded flowing at an average angle of 35° to the isobaths, entraining ambient Lower Circumpolar Deep Water en route. This process is predominant in determining the concentration and placement of the shelf water injected into the deep sea as a precursor Antarctic Bottom Water. Nonetheless, a 4-hour duration pulse of undiluted shelf water was observed at depth (1407 m) directly north of the Drygalski Trough, moving at around 90 degrees to isobaths, and at a speed of 1.4 m/s. Thus the export of Ross Sea shelf water to the deep sea is accomplished within plumes descending at moderate angle to isobaths, punctuated by rapid downhill cascades.

Gordon, Arnold L.; Zambianchi, Enrico; Orsi, Alejandro; Visbeck, Martin; Giulivi, Claudia F.; Whitworth, Thomas; Spezie, Giancarlo

2004-11-01

337

Ultrasonic method for detecting weak plane in slope  

Energy Technology Data Exchange (ETDEWEB)

Slope stability is one of the important factors that affect coal mining in open-cast mines. Currently the method for detecting weak planes is core drilling, which has a low rate of core recovery and therefore might miss the weak plane. An ultrasonic detector has been developed by Fushun Research Institute of Central Coal Mining Research Institute, based on the following principles: sound velocity changes with properties of rock mass; sound velocity changes with variation of density and porosity. This instrument can detect variation of sound velocity in different types of rock, and can judge the position of weak planes. Commercial tests conducted in Haizhou surface mine in Fuxin and West surface mine in Fushun show that the results measured by the instruments conform with actual geological data.

1983-10-01

338

Air-cushion tankers for Alaskan North Slope oil  

Science.gov (United States)

A concept is described for transporting oil from the Arctic to southern markets in 10,000-ton, chemically fueled air-cushion vehicles (ACV's) configured as tankers. Based on preliminary cost estimates the conceptual ACV tanker system as tailored to the transportation of Alaskan North Slope oil could deliver the oil for about the same price per barrel as the proposed trans-Alaska pipeline with only one-third of the capital investment. The report includes the description of the conceptual system and its operation; preliminary cost estimates; an appraisal of ACV tanker development; and a comparison of system costs, versatility, vulnerability, and ecological effect with those of the trans-Alaska pipeline.

Anderson, J. L.

1973-01-01

339

Exact Slope and Interpolating Functions in ABJM Theory  

CERN Document Server

Using the Quantum Spectral Curve approach we compute exactly an observable (called slope function) in the planar ABJM theory in terms of an unknown interpolating function h(\\lambda) which plays the role of the coupling in any integrability based calculation in this theory. We verified our results with known weak coupling expansion in the gauge theory and with the results of semi-classical string calculations. Quite surprisingly at strong coupling the result is given by an explicit rational function of h(\\lambda) to all orders. By comparing the structure of our result with that of an exact localization based calculation of Drukker, Marino and Putrov for a similar observable we conjecture an exact expression for h(\\lambda).

Gromov, Nikolay

2014-01-01

340

New bounds for the height limit of a vertical slope  

Science.gov (United States)

Using the finite element method, the static and kinematic methods of limit analysis provide tools to solve many stability problems in mechanics of continuous media. The classic problem of the height limit of a Tresca or Mises vertical slope subjected to the action of gravity stems naturally from this theory in plane strain. Although the exact solution to this problem remains unknown, the present work has produced precise bounds using the static and kinematic approaches conjointly: the height limit is now between 3·760 and 3·786 C/ , being the weight per unit volume and C the soil cohesion. These tests also show that both methods, used on current workstations with industrial optimization codes such as XPRESS or OSL, are capable of solving any plane problem of limit loads in geotechnics or in structural calculus.

Pastor, J.; Thai, T.-H.; Francescato, P.

2000-02-01

 
 
 
 
341

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

342

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

343

Permanent monitoring of alpine slope instabilities with L1-GPS  

Science.gov (United States)

Since winter 2010/2011, a network of permanent GPS stations is being set up in the Matter Valley (Swiss Alps). The aim is to monitor the time variable movement of potentially instable rock glaciers. The network has been established in the framework of the X-Sense project, currently totaling more than 20 stations. X-Sense is an interdisciplinary project for monitoring alpine mass movements at multiple scales, funded by the Swiss federal program Nano-Tera within the Swiss Science Foundation. The X-Sense stations consist of low-cost L1 GPS receivers coupled with inclinometers. A part of the stations allow for on-line data transmission. The data of the X-Sense L1 GPS network is operationally processed on a daily basis with Bernese GPS software, in a fully automated processing chain. In addition, real-time solutions are computed for the on-line stations. The geodetic potential of low-cost GPS receivers for the precise monitoring of slope instabilities in mountain areas was previously investigated in a feasibility study. It is shown that low-cost GPS units are able to provide reliable and continuous time series of surface displacements at cm-level accuracy in harsh environment, using adequate differential processing techniques. Enhanced algorithms were developed to derive accurate time series of surface velocities based on the GPS displacements. It was shown that the low-cost GPS receivers allow to reliably observe surface velocities even below 1 cm/day, as well as to detect small and short-term velocity changes. In addition, the time series of more than 2 years obtained reveal the capability to detect seasonal velocity variations, as well as inter-annual variations of the velocity pattern. By providing continuous observations of surface motion, the GPS-based permanent monitoring contributes to the understanding of processes linked to permafrost-related slope instabilities.

Limpach, Philippe; Geiger, Alain; Su, Zhenzhong; Beutel, Jan; Gruber, Stephan

2013-04-01

344

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

345

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

346

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

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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

347

At similar angles, slope walking has a greater fall risk than stair walking.  

Science.gov (United States)

According to the CDC, falls are the leading cause of injury for all age groups with over half of the falls occurring during slope and stair walking. Consequently, the purpose of this study was to compare and contrast the different factors related to fall risk as they apply to these walking tasks. More specifically, we hypothesized that compared to level walking, slope and stair walking would have greater speed standard deviation, greater ankle dorsiflexion, and earlier peak activity of the tibialis anterior. Twelve healthy, young male participants completed level, slope, and stair trials on a 25-m walkway. Overall, during slope and stair walking, medial-lateral stability was less, anterior-posterior stability was less, and toe clearance was greater in comparison to level walking. In addition, there were fewer differences between level and stair walking than there were between level and slope walking, suggesting that at similar angles, slope walking has a greater fall risk than stair walking. PMID:21843878

Sheehan, Riley C; Gottschall, Jinger S

2012-05-01

348

Optimal plant root system architectures for preventing soil loss on slopes  

Science.gov (United States)

Plant root systems affect soil fixation on slopes at different scales. A single root exudes mucilage, stimulating microbial activity and adherence between soil particles. Individual root systems enmesh soil particles and bind aggregates. Deeper roots pin soil layers together, reinforcing the shear zone. Roots and macropores created by dead and decomposing roots influence infiltration rates and subsurface flow, even over an entire slope. Root system morphology and how it changes over time and in different substrates modifies the efficacy of any given species to fix soil on a slope. I will discuss the optimal (or not) types of root system architecture for mitigating slope instability. Why and how root system plasticity and temporal modifications occur will be introduced in an attempt to define a conceptual framework for screening plants that can be used to prevent soil loss on slopes. How these data can be successfully included into slope stability models will be discussed.

Stokes, Alexia

2014-05-01

349

The Effect of Rainfall Patterns on the Mechanisms of Shallow Slope Failure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper examines how rainfall patterns affect the mechanisms of shallow slope failure. Numerical modelling, utilising the commercial software SVFlux and SVSlope, was carried out for a coupled analysis of rainfall-induced slope seepage and instability, with reference to a shallow landslide took place in Jabiru, Northern Territory (NT) Australia in 2007. Rainfall events were varied in terms of pattern in this analysis. The results revealed that slopes are sensitive to rainfall pattern when t...

Muhammad Suradi; Andy Fourie

2014-01-01

350

The evolution of the slope breaks in Qiongdongnan Basin and their controlling factors  

Science.gov (United States)

Qiongdongnan Basin (QB) experienced three main tectonic stages in the Cenozoic: rifting, thermal subsidence, and accelerated subsidence. Corresponding to these stages, the slope breaks also underwent three different evolutionary stages, which differed in space and time between the east and west of QB. Structural slope breaks developed during the rifting stage in the Paleocene. Transitional sedimentary strata without obvious slope break developed in the neritic environment during the thermal subsidence stage in the Neocene. Sedimentary slope breaks and gentle slope zone without slope break developed during the accelerated subsidence stage. The sedimentary slope breaks could be further classified into progradational and aggradational types, the starting points of which varied in space and time. Spatially, the progradational sequences in the Ledong and Lingshui sags started at the north of today's deep central basin, distant from the basin edge. In the Songnan and Baodao sags, the aggradational sequences were close to the sag edge and essentially controlled by the underlying major boundary faults. Temporally, sedimentary slope breaks developed early in the east and late in the west and were initially partitioned and eventually unified. Fault activity controlled the types and ending time of structural slope breaks during the rifting stage, while tectonic subsidence controlled the time and places of progradational slope breaks during the accelerated subsidence stage. Sediment supply controlled the superposition patterns of the sedimentary sequences of the sedimentary slope breaks. It is suggested that the evolutionary history of the slope breaks has been primarily affected by the southward transition of the South China Sea ocean ridge, the westward collision of the Philippine Sea Plate, and the dextral strike-slipping of the Red River Fault.

Liu, Jianbao; Sun, Zhen; Wang, Zhenfeng; Sun, Zhipeng; Wang, Zhangwen; Zhao, Zhongxian; Liu, Siqing

2014-12-01

351

Seismic response of rock slopes: Numerical investigations on the role of internal structure  

Science.gov (United States)

The stability of rock slopes is significantly influenced and often controlled by the internal structure of the slope created by such discontinuities as joints, shear zones, and faults. Under seismic conditions, these discontinuities influence both the resistance of a slope to failure and its response to dynamic loading. The dynamic response, which can be characterized by the slope's natural frequency and amplification of ground motion, governs the loading experienced by the slope in a seismic event and, therefore, influences the slope's stability. In support of the Network for Earthquake Engineering Simulation (NEES) project Seismically-Induced Rock Slope Failure: Mechanisms and Prediction (NEESROCK), we conducted a 2D numerical investigation using the discrete element method (DEM) coupled with simple discrete fracture networks (DFNs). The intact rock mass is simulated with a bonded assembly of discrete particles, commonly referred to as the bonded-particle model (BPM) for rock. Discontinuities in the BPM are formed by the insertion of smooth, unbonded contacts along specified planes. The influence of discontinuity spacing, orientation, and stiffness on slope natural frequency and amplification was investigated with the commercially available Particle Flow Code (PFC2D). Numerical results indicate that increased discontinuity spacing has a non-linear effect in decreasing the amplification and increasing the natural frequency of the slope. As discontinuity dip changes from sub-horizontal to sub-vertical, the slope's level of amplification increases while the natural frequency of the slope decreases. Increased joint stiffness decreases amplification and increases natural frequency. The results reveal that internal structure has a strong influence on rock slope dynamics that can significantly change the system's dynamic response and stability during seismic loading. Financial support for this research was provided by the United States National Science Foundation (NSF) under grant CMMI-1156413.

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

2013-12-01

352

Development of a ground displacement measurement method for failed slopes at the toes of landslides  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sediments produced by a slope failure of the toe of a landslide are assumed to prevent the spread of the failure. Thus, sediment removal is an emergency measure that must be done safely while the slope is observed. Observation must also be done safely without requiring workers to enter the failed slope to avoid secondary disasters.

Generally, a non-prism type totalstation is useful to measure ground displacement under such circumstances, because this type of totalstation ...

Higuchi, K.; Fujisawa, K.; Tohei, M.; Okawa, S.; Shimomura, H.; Sakata, T.

2008-01-01

353

Estimating velocity from noisy GPS data for investigating the temporal variability of slope movements  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Knowledge of processes and factors affecting slope instability is essential for detecting and monitoring potentially hazardous slopes. Knowing the timing of acceleration or deceleration of slope movements can help to identify important controls and hence to increase our process understanding. For this methods to derive reliable velocity estimations are important. The aim of this study was to develop and test a method to derive velocities based on noisy GPS data of v...

Wirz, V.; Gruber, S.; Gubler, S.; Purves, R. S.

2014-01-01

354

Diffraction slopes for elastic proton-proton and proton-antiproton scattering  

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The diffraction slope parameter is investigated for elastic proton-proton and proton-antiproton scattering based on the all available experimental data at low momentum transfer values. Energy dependence of the elastic diffraction slopes is approximated by various analytic functions. The expanded "standard" logarithmic approximations allow to describe experimental slopes in all available energy range reasonably. Various approximations differ from each other both in the low en...

Okorokov, V. A.

2008-01-01

355

Slope analysis for elastic proton-proton and proton-antiproton scattering  

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The diffraction slope parameter is investigated for elastic proton-proton and proton-antiproton scattering based on the all available experimental data at intermediate square of momentum transfer in the main. Energy dependence of the elastic diffraction slope is approximated by various analytic functions in a model-independent fashion. The expanded standard logarithmic approximations allow to describe experimental slopes in all available energy range at qualitative level rea...

Okorokov, V. A.

2008-01-01

356

Problems of definitive slopes mining at Doly Nástup Tušimice  

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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...

Martin Vrubel; Dana Sládková

2007-01-01

357

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)

358

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

359

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

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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

360

Influence of cartilage and menisci on the sagittal slope of the tibial plateaus.  

Science.gov (United States)

We analyzed the magnetic resonance studies of the knee in 80 subjects, 45 men and 35 women with a mean age of 38.9 years, who showed no pathological condition of the joint. Using an imaging visualization software, the sagittal longitudinal axis of the tibia was identified. The angle between this axis and a line tangent to the bone profile of the tibial plateau (bone slope) and to the superior border of the menisci (meniscal slope) were calculated. Thickness of anterior and posterior portion of menisci and underlying cartilage were also measured. The bone slope averaged 8° and 7.7° on the medial and lateral sides, respectively. The mean meniscal slope was 4.1° and 3.3° on the medial and lateral sides, respectively, with a significant difference compared with the bone slope. Menisci and underlying cartilage were significantly thicker in their posterior than their anterior portion (7.6 and 5.2 mm, respectively, in the medial compartment; 8.6 and 5.2 mm, respectively, in the lateral compartment). The presence of cartilage and menisci implies a significant decrease in the posterior tibial slope. In the lateral compartment, the greater the bone slope, the larger the difference between bone and meniscal slope, which means that a marked posterior tilt of the lateral tibial plateau is decreased by the cartilage and meniscus. These findings should be taken into account in planning surgical procedures which affect the slope of the articular tibial surface. PMID:22730027

Cinotti, Gianluca; Sessa, Pasquale; Ragusa, Giovanni; Ripani, Francesca Romana; Postacchini, Roberto; Masciangelo, Raffaele; Giannicola, Giuseppe

2013-10-01

 
 
 
 
361

The contribution of particle swarm optimization to three-dimensional slope stability analysis.  

Science.gov (United States)

Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D) slope stability analysis. This paper applied PSO in three-dimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI-3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes. PMID:24991652

Kalatehjari, Roohollah; Rashid, Ahmad Safuan A; Ali, Nazri; Hajihassani, Mohsen

2014-01-01

362

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

363

DEVELOPMENT OF SHALLOW VISCOUS OIL RESERVES IN NORTH SLOPE  

Energy Technology Data Exchange (ETDEWEB)

North Slope of Alaska has huge oil deposits in heavy oil reservoirs such as Ugnu, West Sak and Shrader Bluff etc. The viscosity of the last two reservoir oils vary from {approx}30 cp to {approx}3000 cp and the amount in the range of 10-20 billion barrels. High oil viscosity and low formation strength impose problems to high recovery and well productivity. Water-alternate-gas injection processes can be effective for the lower viscosity end of these deposits in West Sak and Shrader Bluff. Several gas streams are available in the North Slope containing NGL and CO{sub 2} (a greenhouse gas). The goal of this research is to develop tools to find optimum solvent, injection schedule and well-architecture for a WAG process in North Slope shallow sand viscous oil reservoirs. Coreflood, quarter 5-spot study, compositional simulation, wettability, relative permeability study and streamline-based simulation were conducted in this project. 1D compositional simulation results agree reasonably well with those of the slim tube experiments. Injection of CO{sub 2}-NGL is preferable over that of PBG-NGL. MME is sensitive to pressure (in the range of 1300-1800 psi) for the injection of PBG-NGL, but not for CO{sub 2}-NGL. Three hydrocarbon phases form in this pressure range. As the mean thickness of the adsorbed organic layer on minerals increases, the oil-water contact angle increases. The adsorbed organic films left behind after extraction of oil by common aromatic solvents used in core studies, such as toluene and decalin, are thinner than those left behind by non-aromatic solvents, such as cyclohexane. The force of adhesion for minerals aged with just the asphaltene fraction is similar to that of the whole oil implying that asphaltenes are responsible for the mixed-wettability in this reservoir. A new relative permeability model for a four-phase, mixed-wet system has been proposed. A streamline module is developed which can be incorporated in an existing finite-difference based compositional simulator to model water flood, gas flood and WAG flood. Horizontal wells increase well deliverability over vertical wells, but sweep efficiency can decrease. The well performance depends on the well length, position, heterogeneity, and viscosity ratio. The productivity increase due to electromagnetic heating is a function of power intensity, flow rate, and frequency etc. The productivity of a well can be doubled by electromagnetic heating. A high-pressure quarter 5-spot model has been constructed to evaluate the sweep efficiency of miscible WAG floods. WAG displacement reduces bypassing compared to gas floods and improves oil recovery in cores. As the WAG ratio decreased and slug size increased, oil recovery increased. Oil was recovered faster with increased slug size and decreased WAG ratio in the simulations for field cases studied.

Kishore K. Mohanty

2004-12-01

364

Focusing of long waves with finite crest over sloping beach  

Science.gov (United States)

Analytical solutions of nonlinear and linear shallow water-wave equations are important in several counts. These solutions not only provide insight to establish relationship among the parameters of the problem, but also could provide benchmark results for numerical studies. Here, first, we introduce a new analytical solution to study three-dimensional evolution and runup of long waves over linearly sloping beach. Then, we extend our solution to study the canonical problem, i.e. long wave propagation over a sloping beach connected with a constant-depth region. Koshimura et al. (1999, Coastal Eng Japan, v. 41(2), pp. 151-164) solved this problem in the presence of a vertical wall at the shoreline. The same form of solution has also appeared in the propagation of edge waves, as presented by Fujima et al. (2000, Coastal Eng Japan, v. 42(2), pp. 211-236) and recently by Geist (2013, Pure Appl Geophys, doi: 10.1007/s00024-012-0491-7). On the other hand, Carrier (1995, in: Tsunami: Progress in Prediction, Disaster Prevention and Warning, Tsuchiya and Shuto (eds.), pp. 1-20) started with the nonlinear shallow-water-wave equations, reduced the problem into the linear one and solved as an initial-value problem. In the present study, we differ from the existing analytical studies providing initial conditions as recently described by Kanoglu et al. (2013, Proc R Soc A, v. 469, 20130015, doi: 10.1098/rspa.2013.0015). They introduced a new exact analytical solution to study the propagation of a finite strip source over constant-depth using the linear shallow-water wave theory showing the existence of focusing points for realistic N-wave-type initial displacements (Tadepalli and Synolakis, 1994, Proc R Soc Lond A, v. 445, pp. 99-112, doi: 10.1098/rspa.1994.0050). Here, we discuss the existence of focusing point -a point where unexpectedly large wave heights may be observed due to the configuration of the initial waveform- for the canonical problem, a phenomenon already shown for constant-depth basin by Kanoglu et al. (2013). We also discuss effect of focusing over the runup. ACKNOWLEDGEMENTS: We acknowledge the partial support by the TUBITAK (The Scientific and Technological Research Council of Turkey) through the TUBITAK-GSRT (The General Secretariat for Research and Technology of Greece) joint project 109Y387 entitled "Modelling of tsunami generation, propagation and inundation with applications in the Aegean Sea." Also, UK acknowledges the support through EU 603839 ASTARTE Project.

Kanoglu, Utku; Koroglu, Bulent; Aydin, Baran

2014-05-01

365

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

366

Back-analysis and design review of a failed slope at an open-pit coal mine, Mpumalanga, South Africa  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Mining activity in open-pit mines may change material properties over time and as a result, shear strengths are reduced and may lead to slope failures. It is therefore important to design slope geometries with an acceptable probability of failure. In the event of slope failure occurring, the process of back-analysis to determine material properties at failure may lead to slope redesign for safety reasons. A case study is presented from the back-analysis performed on a slope fai...

Selomane, Mmathapelo Annah

2012-01-01

367

Cryogenic focal plane flatness measurement with optical zone slope tracking  

Science.gov (United States)

We describe a non-contact optical measurement method used to determine the surface flatness of a cryogenic sensor array developed for the JDEM mission. Large focal planes envisioned for future visible to near infra-red astronomical large area point-source surveys such as JDEM, WFIRST, or EUCLID must operate at cryogenic temperatures while maintaining focal plane flatness within a few 10's of ?m over half-meter scales. These constraints are imposed by sensitivity conditions that demand low noise observations from the sensors and the large-field, fast optical telescopes necessary to obtain the science yield. Verifying cryogenic focal plane flatness is challenging because ?m level excursions need to be measured within and across many multi-cm sized sensors using no physical contact and while situated within a high-vacuum chamber. We have used an optical metrology Shack-Hartmann scheme to measure the 36x18 cm focal plane developed for the JDEM mission at the Lawrence Berkeley National Laboratory. The focal plane holds a 4x8 array of CCDs and HgCdTe detectors. The flatness measurement scheme uses a telescope-fed micro-lens array that samples the focal plane to determine slope changes of individual sensor zones.

Edelstein, Jerry; Sirk, Martin; Jelinsky, Patrick N.; Besuner, Robert W.; Hoff, Matthew; Perry, Paul; Heetderks, Henry D.; Bebek, Christopher J.; Levi, Michael E.

2011-10-01

368

Quantifying seismic survey reverberation off the Alaskan North Slope.  

Science.gov (United States)

Shallow-water airgun survey activities off the North Slope of Alaska generate impulsive sounds that are the focus of much regulatory attention. Reverberation from repetitive airgun shots, however, can also increase background noise levels, which can decrease the detection range of nearby passive acoustic monitoring (PAM) systems. Typical acoustic metrics for impulsive signals provide no quantitative information about reverberation or its relative effect on the ambient acoustic environment. Here, two conservative metrics are defined for quantifying reverberation: a minimum level metric measures reverberation levels that exist between airgun pulse arrivals, while a reverberation metric estimates the relative magnitude of reverberation vs expected ambient levels in the hypothetical absence of airgun activity, using satellite-measured wind data. The metrics are applied to acoustic data measured by autonomous recorders in the Alaskan Beaufort Sea in 2008 and demonstrate how seismic surveys can increase the background noise over natural ambient levels by 30-45 dB within 1 km of the activity, by 10-25 dB within 15 km of the activity, and by a few dB at 128 km range. These results suggest that shallow-water reverberation would reduce the performance of nearby PAM systems when monitoring for marine mammals within a few kilometers of shallow-water seismic surveys. PMID:22087932

Guerra, Melania; Thode, Aaron M; Blackwell, Susanna B; Michael Macrander, A

2011-11-01

369

Debris Flows Within The Greater Caucasus Northern Slope  

Science.gov (United States)

Debris flows are recorded everywhere within the Greater Caucasus northern slope. In last decades studies of debris flows appeared to be very important due to an intensive anthropogenic activity in the mountainous areas. Debris flow spatial distribution, as well as their genesis and means of protection are critical, too. The studied terri- tory has significant absolute altitudes, especially in the central and eastern parts. Also large amount of atmospheric precipitation with maximum in a warm period is typical for the region. Modern glaciation with soil-covered moraine deposits of modern and Holocene age is developed in the region. Geological and geomorphological conditions lead to debris flows formation within the entire territory. However, the amount of atmospheric precipitation drastically decreases from west to east and in the eastern part (Dagestan) debris flow is less active than in the central even under the presence of enormous amounts of loose detrital material of different genesis. In the western part debris flows are less developed due to insignificant altitudes and considerable forest coverage and soil-cover. Powerful modern glaciation with vast development of purely moraine and fluvial-glacial deposits results in intensive debris flow activity in the central part of the northern slope (the Terek river basin). In the upper reaches of all the Terek tributaries moraine deposits reach up to several dozen meters. They are widespread at altitudes higher than 2000 m (above the forest boundary) and almost everywhere uncovered by soils. They are a key source of sediments under debris flow formation. Within the Greater Caucasus northern slope there are 1700 debris flow basins with the total area about 7000 km2. Their average area is 4.0 km2 with minimum 0.20 km2 and maximum 173.8 km2. Moreover, there are many riverbeds in the area where form mountain mud floods more than 3000 km long. Debris flows occur between January and October with clear altitudinal zoning: at the lower levels (up to 1500 m) they are recorded for a longer period and higher than 2000 m only 2-3 months. In terms of genesis the following types of debris flows are registered: rain, glacial and mixed. Rain mudflows are formed due to intensive rains (the daily amount is about 25 U 100 mm). A critical norm of precipitation forming debris 1 flows varies from west to east. In the western part it is 75-100 mm, central U 50-75 mm and eastern U 25-50 mm. Also the norm varies from north to south, in particular on advanced ridges it is higher but on the Glavny and Bokovoy ridges it is less. The difference is about 2 times. Glacial mudflows are observed only in the areas of modern glaciation. They form under high air temperature (20 U 25°C) leading to an intensive melting of snow and ice on glaciers. High air temperature should be recorded not less than 5-10 days. Mixed mudflows form under high air temperature in the glaciers area and significant rainstorms in the glacial zone. Rainstorms cause debris flow formation in focal points. Frontal precipitation with a significant amount of rain cause debris flows at vast territories often covering several kilometers. In total rain mudflows prevail on the Greater Caucasus northern slope and equal 60 - 80% of all the mudflows. Glacial mudflows constitute 30-40% and mixed mudflows U 10-20%. In the western and eastern parts rain mudflows are the principal and their share is 80-90% of all the mudflows. In the central part glacial mudflows prevail (60- 0%). Technogenic mudflows are recorded in the areas with developed mining industry, highways, forestry, and pastures. In the given region debris flows distribute from north to south depending on genesis and volume. On advanced ridges (Lesisty, Pastbishny, Skalisty) only rain mudflows are registered with the volume up to 100,000 m3. Eluvial-deluvial, alluvial-proluvial and eolian-proluvial deposits compose their solid constituents. This is a zone of weak mudflow hazard. The most often are mudflows with volume up to 5000-10,000 m3. More powerful mudflows are less frequent (once

Panova, S.

370

Commercial possibilities for stranded conventional gas from Alaska's North Slope  

Science.gov (United States)

Stranded gas resources are defined for this study as gas resources in discrete accumulations that are not currently commercially producible, or producible at full potential, for either physical or economic reasons. Approximately 35 trillion cubic feet (TCF) of stranded gas was identified on Alaska’s North Slope. The commercialization of this resource requires facilities to transport gas to markets where sales revenue will be sufficient to offset the cost of constructing and operating a gas delivery system. With the advent of the shale gas revolution, plans for a gas pipeline to the conterminous US have been shelved (at least temporarily) and the State and resource owners are considering a liquefied natural gas (LNG) export project that targets Asian markets. This paper focuses on competitive conditions for Asian gas import markets by estimating delivered costs of competing supplies from central Asia, Russia, Indonesia, Malaysia, and Australia in the context of a range of import gas demand projections for the period from 2020 to 2040. These suppliers’ costs are based on the cost of developing, producing, and delivering to markets tranches of the nearly 600 TCF of recoverable gas from their own conventional stranded gas fields. The results of these analyses imply that Alaska’s gas exports to Asia will likely encounter substantial competitive challenges. The sustainability of Asia’s oil-indexed LNG pricing is also discussed in light of a potentially intense level of competition.

Attanasi, Emil D.; Freeman, Philip A.

2014-01-01

371

Stability and evolution of dense currents on sloping topography  

Science.gov (United States)

Driven by a need to understand the propagation and stability of abyssal ocean currents, there have been numerous idealised studies examining the dynamics in a rotating frame of reference of dense fluid on a slope underlying a less dense ambient fluid. This circumstance is characteristic, for example, of the Denmark Strait Overflow and the Western Boundary Undercurrent. A starting point of many theoretical and numerical studies is to assume the ambient is stationary and the current moves initially at a constant speed set by geostrophic balance. However, recent laboratory experiments (e.g. Lane-Serff and Baines (1998)) have shown that the continuous injection of a dense current from a localised source can significantly accelerate the ambient fluid and the consequent interaction between the two moving fluids cannot be neglected. We have performed a series of laboratory experiments designed to examine the temporal as well as spatial stability characteristics of the current. In these experiments a 90 centimetre diameter cylindrical tank on a rotating table is filled with fresh water. Dyed salt-water is injected uniformly through an annular slit on the conical-shaped bottom of the tank thus creating a uniform circular current. When instability occurs we observe a sinusoidal mode with phase speed approximately equal to that of the induced surface flow. The results are shown to be consistent with barotropic instability of the ambient rather than baroclinic instability of the dense current.

Sutherland, B. R.; Nault, J.; Yewchuk, K.; Swaters, G. E.

2003-04-01

372

Ronchigram analysis based on effective wavelength techniques and wavefront slope  

Science.gov (United States)

In this paper, some concepts and results associated with the interferometric concept of effective wavelength have been applied for the evaluation of optical surfaces. This testing technique measures the wavefront slope instead of the contour of the wavefront, like in the conventional interferometry. Therefore in this paper we present two methods of analysis of optical surfaces with the Ronchi test. First, we described a procedure to evaluate surfaces employing the effective wavelength in the Ronchi test [1]. Our results were computationally processed in order to reconstruct the wavefront of a particular mirror by means of the effective wavelength. A second proposal technique of analysis is based on the change of the traditional analysis of a ronchigram to a method by a proper scaling of the shearing interferogram, via the equivalent wavelength. The effective wavelength and equivalent wavelength are distinct concepts and are independent of the wavelengths used in the image registering process. Comparisons of the Zernike Polynomials for each wavefront with a reference wavefront show, the differences between both methods. Finally, we discuss some advantages and disadvantages of each of the proposed analysis and mention the principal factors to improve our results.

Granados-Agustin, F. S.; Garcia-Arellano, A.; Aguirre-Aguirre, D.; Campos-Garcia, M.; Cornejo-Rodriguez, A.

2011-05-01

373

[Mechanisms of grass in slope erosion control in Loess sandy soil region of Northwest China].  

Science.gov (United States)

By adopting the method of simulated precipitation and from the viewpoint of slope hydrodynamics, in combining with the analysis of soil resistance to erosion, a quantitative study was made on the mechanisms of grass in controlling the slope erosion in the cross area of wind-water erosion in Loess Plateau of Northwest China under different combinations of rainfall intensity and slope gradient, aimed to provide basis to reveal the mechanisms of vegetation in controlling soil erosion and to select appropriate vegetation for the soil and water conservation in Loess Plateau. The grass Astragalus adsurgens with the coverage about 40% could effectively control the slope erosion. This grass had an efficiency of more than 70% in reducing sediment, and the grass root had a greater effect than grass canopy. On bare slope and on the slopes with the grass plant or only the grass root playing effect, there existed a functional relation between the flow velocity on the slopes and the rainfall intensity and slope gradient (V = DJ(0.33 i 0.5), where V is flow velocity, D is the comprehensive coefficient which varies with different underlying surfaces, i is rainfall intensity, and J is slope gradient). Both the grass root and the grass canopy could markedly decrease the flow velocity on the slopes, and increase the slope resistance, but the effect of grass root in decreasing flow velocity was greater while the effect in increasing resistance was smaller than that of grass canopy. The effect of grass root in increasing slope resistance was mainly achieved by increasing the sediment grain resistance, while the effect of canopy was mainly achieved by increasing the slope form resistance and wave resistance. The evaluation of the soil resistance to erosion by using a conceptual model of sediment generation by overland flow indicated that the critical shear stress value of bare slope and of the slopes with the grass plant or only the grass root playing effect was 0.533, 1.672 and 0.925 Pa, respectively. PMID:23717998

Zhao, Chun-Hong; Gao, Jian-En; Xu, Zhen

2013-01-01

374

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

375

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

376

Catastrophic impact of hurricanes on atoll outer reef slopes in the Tuamotu (French Polynesia)  

Science.gov (United States)

Underwater effects on coral reefs of the six hurricanes which ravaged French Polynesia between December 82 and April 83 were observed by SCUBA diving around high islands and atolls during September and October 1983. Special attention was paid to Tikehau atoll reef formations (Tuamotu archipelago) where quantitative studies on scleractinians, cryptofauna and fishes were conducted in 1982 immediatly prior to the hurricanes. On outer reef slopes coral destruction, varying from 50 to 100%, was a function of depth. Upper slope coral communities composed of small colonies well adapted to high energy level environments, suffered less than deeper formations. However, there is a narrow erosional trough in this zone at a depth of 6 m that was probably the result of storm-wave action (plunge point). Coral destruction was spectacular at depths greater than 12 m: 60 to 80% between 12 m and 30 m and 100% beyond 35 m, whereas earlier living coral coverage ranged from 60 to 75% in these zones. The outer slope was transformed into a scree zone covered with coarse sand and dead coral rubble. Dives on different sites around steep outer slopes (>45°) of the atolls and more gentle slopes (slopes broken colonies were thrown up on reef flats and beaches; on steep slopes avalanches destroyed much of the living corals and left scree slopes of rubble and sand.

Harmelin-Vivien, Mireille L.; Laboute, Pierre

1986-10-01

377

The Relationship Between Lithology and Slope Morphology in the Tucson Mountains, Arizona.  

Directory of Open Access Journals (Sweden)

Full Text Available The relationship between lithology and slope morphology is investigated at eight sites on granitic, andesitic, andsedimentary hillslopes in the Tucson Mountains, Arizona. Several methods are used in the study. Topographic profi lesare constructed. Skewness indices, slope length, and mean slope angles of the different slope profi les are computed andcompared with each other. Debris size analysis has permitted for some profi les, the determination of hillfront/piedmontjunctions. The nature and structural characteristics of the bedrock are the ones that determine the hillslope morphologyin this semi-arid region. There are, as a matter of fact, variations in profi les on the same bedrock nature but differentlyexposed. More precise morphologic studies have been also done in comparing the different lithologic pairs. They havepermitted to show some similarities in shapes. The granitic-andesitic slopes and andesiic-sedimentary slopes are thebest comparisons which show the relationship between lithology and slope morphology. The granitic-sedimentary sloperelationship is shown in the hillfront concavities, mountain front and piedmont mean slope angles.

Kamel Khanchoul

2008-05-01

378

Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge  

Science.gov (United States)

Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the post-failure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.

Li, N.; Cheng, Y. M.

2014-09-01

379

Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge  

Directory of Open Access Journals (Sweden)

Full Text Available Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the post-failure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.

N. Li

2014-09-01

380

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

 
 
 
 
381

Protection Roles of Gleditshia Caspica Dsf. on Slopes in Iran  

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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

382

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

383

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.

384

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

385

The Effect of Rainfall Patterns on the Mechanisms of Shallow Slope Failure  

Directory of Open Access Journals (Sweden)

Full Text Available This paper examines how rainfall patterns affect the mechanisms of shallow slope failure. Numerical modelling, utilising the commercial software SVFlux and SVSlope, was carried out for a coupled analysis of rainfall-induced slope seepage and instability, with reference to a shallow landslide took place in Jabiru, Northern Territory (NT Australia in 2007. Rainfall events were varied in terms of pattern in this analysis. The results revealed that slopes are sensitive to rainfall pattern when the rainfall intensity has a high degree of fluctuation at around the same value as that of saturated hydraulic conductivity. Average rainfall intensity at the beginning of a rainfall period plays a primary role in determining the rate of decrease in initial factor of safety (Fi towards minimum factor of safety (Fmin. The effect of rainfall events on the slope instability is attributed to the amount of rainwater infiltration into slope associated with rainfall pattern.

Muhammad Suradi

2014-04-01

386

Origin and palaeoclimatic significance of the Pleistocene slope covers in the Cracow Upland, southern Poland  

Science.gov (United States)

Periglacial slope covers in the southern part of the Cracow Upland, S Poland can be grouped in five genetic categories: slope loess, washed loess, weathered debris, scree deposits, low-density flow deposits, and solifluctites or high-density flow deposits. They differ from each other with respect to their morphological position in relation to the slope, and in lithological characteristics. It was found that successive generations of slope deposits can be distinguished according to their degree of chemical weathering, which can be estimated on the basis of the presence and morphology of limestone clasts, on the content and colour of the colloid clay, and on the Fe 2O 3 and CaCO 3 content of the clay particles. This paper contributes to a discussion on the possibility of palaeoclimate reconstruction based on slope deposits analyses.

Pawelec, Halina

2006-03-01

387

The deformation prediction of mine slope surface using PSO-SVM model  

Directory of Open Access Journals (Sweden)

Full Text Available Based on the main factors with important influence on thedeformation of the mine slope, a new methodintegrating support vector machine (SVM and particleswarm optimization (PSO was proposed to predict thedeformation of mine slope surface. Themeteorological factors and the deformation data of the research area are acquired using the advanced deformation monitoring equipment GroundBased-Synthetic Aperture Radar (GB-SAR.Then the SVM is used to predict the mine slope deformation. The PSO is employed to optimize the structure parameters of the SVM. The proposed newmethod was applied to predict the mine slope surface deformation of theAnjialing diggings in China. The obtained experiments results indicated thatthe proposed method can provide precise prediction of the mining slope surfacedeformation and its performance is superior to its rivals.

Sunwen Du

2013-07-01

388

The investigation of sloping cultivated land on the Loess Plateau with 3S technology  

Science.gov (United States)

The hill and ravine area on the Loess Plateau is the typical region of serious soil erosion, excess reclamation, and deteriorated eco-environment in middle reaches of Yellow River. The main project of eco-environment construction is that recover vegetation, and quit high sloping cultivated land to forest or meadow. The local government in the concerned region poses that sloping cultivated land higher than 15 degree should quit. How many are there qualified and how about their distribution? These are the basis problems of the execution of the eco-environment construction project. In this paper, using TM image and digital relief map, the interpretation of land use classification and the calculation of slope are made for Baota , Yan"an, with the software of ARC/INFO and ERDAS IMAGINE. And also the sloping cultivated land is mapped, basing on the composite analysis of land use map and slope map.

Li, Dengke; Liu, Anlin; Deng, Fengdong; Zhang, Jinghong; Zhuo, Jing

2003-07-01

389

Developing slope stability radar technology to improve safety and productivity in the global mining industry  

Energy Technology Data Exchange (ETDEWEB)

The management of risks associated with slope instability is an essential process in the safe and economic operation of open-cut mines. In four years, over 70 slope stability radar (SSR) system have been installed at major mines in Australia, Indonesia, Africa, Chile, Peru, United States, Canada and Europe to better manage those risks. The article discusses sloep stability hazards and rock slope monitoring and management in open-pit mines and goes on to describe the relatively new techniques of the Ground Probe slope stability radar (SSR) for monitoring mine walls and general slopes. The first SSR to be deployed in Africa was in 2003. Soonafter a mobile Pit Evacuation Alarm Sytem, was developed by GroundProbe South Africa. This includes an electronic mapping and global positioning system (GPS) for accurate real time tracking. Research is planned to itegrate additional data sources with the SSSR systems and provide remote delivery of this data. 2 figs.

Harries, N.; Noon, D. [GroundProbe (Australia)

2009-10-01

390

Alaska Kuparuk North Slope oil separator upgrade : case study  

Energy Technology Data Exchange (ETDEWEB)

The ConocoPhillips Kuparuk facility on Alaska's North Slope is part of the second largest oil field in North America. It is located on the Arctic coastal plain 40 miles west of Prudhoe Bay; an environment with extreme weather temperatures. Instruments must be specified for high reliability and maintenance free operations. The existing first stage production separator had to be upgraded when ConocoPhillips brought on a new oil field with heavy oil and high solids content. The original separator used traditional displacers and differential pressure cells for both oil and interface measurements. This paper presented the case study based on operator feedback and real time, on-line screen shots and trending data. It demonstrated how new and traditional measurement technologies perform under extreme temperature conditions and in cases where oil with high solids concentration is difficult to separate. The study reviewed the following novel measurement technologies: the Tracerco Profiler, Guided Wave Radar, internal displacers and external differential pressure cells. The new West Sak oil field was brought on stream in August 2004, and a Tracerco Profiler was installed as part of the vessel upgrade. It was given a final calibration with the well fluids. The density bands were adjusted to cater for sand, water, emulsion, oil and foam levels. The Tracerco Profiler was found to be very useful in identifying emulsion build-up, making it possible to control build up with chemicals. The interface control was improved by tuning on the water outlet valves. Foaming was minimal due to antifoam treatments. An unexpected advantage was the sand monitoring capability and the ability to know when to sand jet. 9 figs.

Lees, R. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Tracerco, Houston, TX (United States)

2005-11-01

391

Nitrogen deposition along differently exposed slopes in the Bavarian Alps.  

Science.gov (United States)

The Alps are affected by high nitrogen deposition, particularly in the fringe of the Northern and Southern Alps. In the framework of a two-year monitoring study performed in 2010 and 2011, we investigated the ammonia and nitrogen dioxide air concentration and ammonium and nitrate deposition at different altitudes between 700 and 1,600 ma.s.l. in the Garmisch-Partenkirchen district in the Upper Bavaria region (Germany). Four-weekly measurements of deposition collected with bulk open field samplers and under-crown were performed in a profile perpendicular to the axis of the Loisach valley; measurements were conducted at eight sites. Whereas open field deposition ranged from 5 to 11 kg ha(-1)a(-1), nitrogen throughfall has reached up to 21 kg ha(-1)a(-1). Data from the valley and the slopes were compared with measurements performed on the platform of the Environmental Research Station Schneefernerhaus (Zugspitze) at an altitude of 2,650 ma.s.l. For the rough estimation of the total yearly deposition rate of nitrogen, the canopy uptake model was applied. By regarding nitrogen uptake by the trees, total deposition can exceed the throughfall in all sites by up to 50%. Additionally, we estimated the total deposition