WorldWideScience
1

Sedimentary facies and progradational style of a Pleistocene talus-slope succession, Northern Calcareous Alps, Austria  

Science.gov (United States)

In mountain ranges, talus slopes are ubiquitous and typically represent the highest deposystem. The style of talus buildup from a low-dipping, immature slope to a high and steep, geomorphically mature slope, however, to date was not documented. Near Innsbruck city (Austria) a lithified talus-slope succession records progradation and downlap via talus-associated alluvial fans along its toe-of-slope; the fans linked progradation of the steep-dipping talus-slope segment over a lower-dipping substrate. The considered succession ('Hötting Breccia' Auct.) probably accumulated during the terminal Riss-Würm interglacial to early Würmian, and became lithified before the Last Glacial Maximum. The Hötting Breccia consists of alluvial-fan deposits which, in turn, are locally downlapped by a succession of aggrading to prograding talus slopes. Up-hill, the fossil talus slopes pinch out in onlap onto former rock cliffs. In the eastern part of outcrop, talus buildup is well-exposed along the flanks of a canyon; there, facies and depositional geometries record: (a) a basal, low-dipping alluvial-fan interval that accumulated near the toe-of-cliff, overlain and downlapped by (b) a steeper-dipping talus-slope succession. In the steep-dipping (25-35°), proximal talus-slope segment hundreds of meters in length, the talus successions consist mainly of: (i) clast-supported breccias of cohesive debris flows, intercalated with (ii) openwork breccias from grain flows and particle creep. Progradation of the steep-dipping segment of talus slopes took place via shingling of alluvial-fan depounits along the toe-of-slope. The fans linked the progradation of the steep-dipping, proximal talus-slope segment with the lower-dipping substrate ahead of the talus slope. The change from alluvial-fan deposition along the toe of initially high cliffs towards climbing onlap and progradation of talus slopes occurred when a slope segment dipping with the mean angle of residual shear of talus material had formed at the apex of the fan. Because the free cliff face supplying talus deposition diminishes with time, the progradation potential of talus slopes is inherently limited.

Sanders, Diethard

2010-07-01

2

Paediatric talus fracture.  

LENUS (Irish Health Repository)

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

Byrne, Ann-Maria

2012-01-01

3

Reef talus: A popular misconception  

Science.gov (United States)

Reef fronts have traditionally been regarded as comprising debris derived by contemporaneous erosion of 'the reef'. However, evidence from wave transport indicates that on present-day reefs the bulk of the debris generated in this way accumulates in the back-reef area, with only finer-grained sediment carried off-reef by retreating flows or by overwash. Nevertheless, in contrast to this observation, 'fore-reef' debris slopes are commonly considered "characteristic" of Phanerozoic reefs. This apparent error reflects the conflation of processes defining contemporary growth and accretion of the reef, and the corresponding long-term accretion of the carbonate platform on which it rests. Present-day reefs are commonly (although not exclusively) additions to long-lived carbonate platforms. Growth of the latter is intermittent and has been moderated by changes in sea-level that, for recent reefs, have been on time scales of less than 100 ka. During low sea-level stands, growth ceases or is translated downslope and earlier deposits are subject to lithification and subaerial erosion. Similar changes are applied on a larger scale to the aggrading growth of carbonate platforms, but the bulk accretion of these includes quite different processes and reflects far longer timescales. During low sea-level stands, the margins of platforms commonly become unstable, with instability reflected in slope failure and in the shedding of blocks, ranging from metres to kilometres in diameter, associated with the generation of debris flows and turbidites. It is argued that these are the materials that are commonly described as 'reef talus' in ancient structures, although their formation is largely independent of any contemporary reef growth. Difficulties arise where 'the reef' and 'the platform' are treated as a single functional entity. It is important to recognize the conceptual distinction between them, 'reef talus' is a misleading description of the debris predominantly generated by platform erosion and slope failure.

Braithwaite, Colin J. R.

2014-01-01

4

Fracture Bilateral Talus in Children  

Directory of Open Access Journals (Sweden)

Full Text Available Talar body injuries are rare, particularly in children. To our knowledge, there has not been a single case report of bilateral talus fracture in a child till date. We report two cases of fracture bilateral talus in children. The first case is of a fracture separation of the distal tibial epiphysis and a fracture of the body of the talus with subluxation of ankle on right side and a fracture neck of talus on left side. The second is fracture bilateral talus with epiphyseal injury of left distal tibia. A minimal or undisplaced fracture of talus is less likely to undergo avascular necrosis than a displaced fracture but even with optimal treatment, avascular necrosis may still occur. It is of prime significance that these fractures should be diagnosed well in time to avert complications. Therefore an appropriate length of follow-up is required.

Vinit Verma

2013-08-01

5

Completely extruded talus without soft tissue attachments  

OpenAIRE

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 rock-climbing 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, anticipat...

Jin-Soo Suh; Sang Woo Kim; Ho Seong Lee; Jae Jung Jeong; Young Rak Choi

2011-01-01

6

Osteosarcoma of the talus: a case report.  

Science.gov (United States)

The reported incidence of osteosarcoma of the foot is very low. Osteosarcoma of the talus is extremely rare and few cases have been reported in the literature. The clinical findings are not typical, and osteosarcoma of the talus can be easily misdiagnosed, resulting in a delay in proper treatment. We report the case of a patient with osteosarcoma of the talus, from a series of 120 osteosarcomas treated at our hospital between 1966 and 2002. PMID:16570907

Seijas, Roberto; Minguell, Joan; Pérez, Manuel

2006-01-01

7

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

8

Completely extruded talus without soft tissue attachments.  

Science.gov (United States)

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 rock-climbing 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. PMID:24765266

Choi, Young Rak; Jeong, Jae Jung; Lee, Ho Seong; Kim, Sang Woo; Suh, Jin-Soo

2011-03-29

9

14C age of the talus deposits distributed in the middle course of the river Obirashibe, northern Hokkaido, Japan  

International Nuclear Information System (INIS)

The samples for the determination of the 14C age of the talus deposit were collected from Takinoshita, Obira town, Rumoe district, Hokkaido. The stratigraphy and the sequence of deposits were as follows: 1) T1 terrace deposit, 2) mud flow deposit, 3) T2 terrace deposit (lake deposit), 4) talus deposit, 5) large rock slide. The obtained 14C age of 23750+-620 Y.B.P. showed the lower limit of talus deposit and the upper limit of lake deposit. The 14C age 29060+-2180 Y.B.P. of the mud flow deposit was regarded as the lower limit of the lake deposit. The formation of lake deposit was estimated to be in the period of 29000-24000 years ago. The obtained age showed good correspondence with the results of pollen analysis which indicated the climate-mitigating period in last glacial epoch. Consequently, the lake deposit of this area was regarded as to be formed in the similar weather condition mentioned above. Talus deposit contained wood pieces in its basement, but fossil pollens and the relics of lage plants were not found. This means that the talus deposit was formed continuously without vegetation. The weather condition in which the deposits were formed are as follows. 1) Mud flow deposit was formed by the large collapse of mountain side slope in the last stage of [Biraotori moor period]. 2) Lake deposit was formed in the period of weather mitigation of 29000-26000 years ago. 3) Talus deposit was formed under the cold a Talus deposit was formed under the cold and dry periglacial condition 24000 years ago and on. (Ishimitsu, A.)

10

Primary subacute osteomyelitis of the talus.  

Science.gov (United States)

In four children with primary subacute osteomyelitis of the talus seen one to five months from the onset of symptoms, the only constant complaints were of pain and a limp. All four were treated by curettage, immobilisation in plaster and appropriate antibiotics. All the bony cavities were healed within eight months of the operation and there were no growth disturbances nor any abnormalities of the adjacent joints. PMID:6693465

Skevis, X A

1984-01-01

11

Environmental impact of introducing plant covers in the taluses of orchard terraces: implications for erosion and agricultural runoff control  

OpenAIRE

South-eastern Spain, and in particular the coastal areas of Granada and Malaga, feature a large area under subtropical crops, with orchards established on terraces built along the slopes of the mountainous areas. The climate, characterized by periodically heavy rainfall, variable in space and time, and with the common agricultural practice of leaving the taluses with bare soil, are the main factors encouraging soil erosion, runoff, and subsequent transport of pollutants. Over a two-year perio...

Rodriguez Pleguezuelo, C. R.; Duran Zuazo, V. H.; Francia Martinez, J. R.; Martin Peinado, F. J.; Graaff, J.; Muriel Fernandez, J. L.

2011-01-01

12

Benign chondroblastoma of talus demonstrated by skeletal scanning.  

Science.gov (United States)

A patient with a benign condroblastoma of the talus bone is described. A review of the pathogenesis and more common sites of predilection of this unusual tumor is presented. This is the first case, to our knowlege, shown by labeled phosphate scanning. PMID:657655

Ulreich, S; Swartz, G; Stier, S A; Philips, E

1978-02-01

13

A Case Report of Sequela of Operation of Talus Osteonecrosis  

Directory of Open Access Journals (Sweden)

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

Choi Sung-Hun

2006-02-01

14

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

Science.gov (United States)

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

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

2013-08-01

15

Nonoperative treatment of closed total talus dislocation without fracture: A case report and literature review  

Science.gov (United States)

Complete dislocation of the talus not accompanied by a fracture is a very rare injury. Most cases reported are open talus dislocations; closed dislocations are rarely seen. The functional prognosis is poor due to osteonecrosis of the talus which develops in the majority of cases. We present a case of lateral dislocation of the left talus in a 29-year-old road accident victim, but no fracture could be detected in the talus and any of malleolus. Reduction of dislocation had been performed in emergency by external manipulation. At 1-year follow-up, the right ankle was pain free and stable. Motion was satisfactory: 15° dorsal flexion, 30° plantar flexion; the talus didn't show subluxation and avascular necrosis could not be detected.

Rhanim, Abdelkarim; Zanati, Rachid El; Younes Ouchrif; Hassani, Zouhir Ameziane; Kharmaz, Mohammed; Berrada, Mohammed Saleh

2014-01-01

16

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

International Nuclear Information System (INIS)

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

17

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

Energy Technology Data Exchange (ETDEWEB)

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

Okamoto, Hideaki; Shibata, Yoshimori; Nishi, Genzaburo; Tago, Kyoji; Tsuchiya, Daiji; Chiba, Takehiro; Okumura, Hisashi [Aichiken Koseiren Kainan Hospital, Yatomi (Japan); Ikeda, Takeshi; Wada, Ikuo

2000-02-01

18

Isolated tuberculosis of talus without ankle and subtalar joint involvement.  

Science.gov (United States)

This case has been reported because of its rarity and atypical clinical presentation. An 8-year-old boy presented with a gradually increasing swelling localised on the antero-medial aspect of the foot haemogram, erythrocyte sedimentation rate (ESR), Mantoux and X-ray chest were normal. An irregular lytic lesion of the talus was seen on the x-ray of the affected part. Ziehl Nelson staining of the aspirated fluid revealed acid-fast bacilli. Material obtained after curettage and bone grafting was sent for histopathological examination which confirmed the diagnosis of tuberculosis. Post operatively a below knee cast was given for 12 weeks and anti tubercular treatment was given for 20 months. At the end of the treatment patient had full and painless motion at the ankle and subtalar joint. The lytic lesion had healed on X-ray. PMID:12440280

Anand, A; Sood, L K

2002-09-01

19

Slope filtrations  

OpenAIRE

Many slope filtrations occur in algebraic geometry, asymptotic analysis, ramification theory, p-adic theories, geometry of numbers... These functorial filtrations, which are indexed by rational (or sometimes real) numbers, have a lot of common properties. We propose a unified abstract treatment of slope filtrations, and survey how new ties between different domains have been woven by dint of deep correspondences between different concrete slope filtrations.

Andre?, Yves

2008-01-01

20

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.)

21

Approach alternatives for treatment of osteochondral lesions of the talus.  

Science.gov (United States)

Osteochondral lesions of the talus are common injuries, especially in the athletic population. Although multiple etiologies exist, lateral lesions have a higher incidence of association with a specific traumatic event. It has been postulated that lateral lesions are produced when the anterolateral aspect of the talar dome impacts the fibula on application of an inversion or dorsiflexion stress to the ankle [2]. There is general agreement that surgery should be performed only in symptomatic cases, as osteochondral lesions of the talar dome show little tendency to progression and do not seem to lead to osteoarthritis [10,42]. Appropriate preoperative imaging is extremely important. Standard radiographs of the ankle supplemented with lateral plantar flexion and dorsiflexion views and CT or Mr imaging can be helpful in evaluating the size, depth, and exact location of the lesion. This information is essential in planning the appropriate surgical procedure. Although many stage I and II lesions respond well to conservative therapy and a period of immobilization, some higher-grade lesions (stage III and IV) eventually require surgical intervention. Most lesions can be approached arthroscopically. Many arthroscopic procedures have been shown to be successful, including debridement with abrasion chondroplasty, subchondral drilling, and microfracture [18-20]. But certain larger or refractory lesions may require an open approach to the ankle joint to restore the articular cartilage. Most lateral lesions have an anterior location and are easily accessible through a standard anterolateral approach. Most medial lesions are located on the posterior talar dome, and a medial malleolar osteotomy is usually required. Osteotomies, in particular of the medial malleolus, should be approached carefully. The possible complications of nonunion and malunion can lead to progressive arthritis of the ankle joint. PMID:12512414

Navid, David O; Myerson, Mark S

2002-09-01

22

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

Science.gov (United States)

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

23

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

Science.gov (United States)

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

24

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.

25

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

Energy Technology Data Exchange (ETDEWEB)

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{sup -}1 yr{sup -}1, and for runoff 34.1 and 6.8 mm yr{sup -}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.

Rodriguez Pleguezuelo, C. R.; Duran Zuzo, V. H.; Martin Peinado, F. J.; Franco Tarifa, D.

2009-07-01

26

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 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.

27

[Neonatal osteomyelitis of the talus due to methicillin-resistant Staphylococcus epidermidis].  

Science.gov (United States)

Acute osteomyelitis is a relatively rare disorder in the neonatal period, with considerable morbidity and mortality. Early diagnosis and prompt treatment are essential for a successful outcome. In this report we present a case of acute osteomyelitis of the talus due to methicillin-resistant Staphylococcus epidermidis, observed in a 30-day-old infant. PMID:23774980

Pampinella, Diego; Serra, Gregorio; Giordano, Salvatore; Dones, Piera; Di Gangi, Maria; Failla, Maria Concetta; Corsello, Giovanni

2013-06-01

28

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)

29

Fracture of the lateral process of the talus: appearance at MR imaging and clinical significance  

International Nuclear Information System (INIS)

The case of a 59-year-old man with chronic lateral ankle pain following an inversion injury is presented. MR imaging performed to evaluate for soft tissue injury revealed an unsuspected fracture of the lateral process of the talus. The patient underwent surgical exploration of the fracture with debridement of adjacent loose bodies and is currently undergoing aggressive physical rehabilitation. (orig.)

30

Controls on Groundwater Flow in an Alpine Talus-Moraine Complex  

Science.gov (United States)

Since alpine watersheds are the headwaters of rivers acting as major sources of water, there is growing concern over water shortages in areas dependent on mountain runoff. Talus and moraine complexes, as well as fractured bedrock, are a dominant hydrologic response unit within the Lake O'Hara Research Basin (LORB) in Yoho National Park, British Columbia. In this alpine environment, previous studies have shown that groundwater plays an important hydrological role. Although little is known about groundwater storage in these media, they are likely a significant groundwater reservoir and an important control on groundwater flow. The goals of this study are to develop a conceptual model of the talus and moraine complex and the fractured bedrock. The approximately 0.3km2 Babylon drainage basin within the LORB was chosen as the study site as it contains a talus and moraine complex that drains into one gaugeable stream. The conceptual model of this basin has been developed using geophysical, hydrological and hydrogeological methods. Three Ground Penetrating Radar (GPR) and Electrical Resistivity Imaging (ERI) surveys were used to characterize the subsurface structure and water distribution within the talus and moraine complex. The bedrock surface is clearly defined in the GPR profiles and its elevation agrees with that in the ERI inversions. Highly resistive talus material is observable in the ERI results, and areas of low resistivity are found within the bedrock. Hydraulic conductivity estimates of the geologic media, calculated using tracer slug injection and baseflow recession analysis methods, fall within the ranges from gravel to fractured rock. Isotopic hydrograph separations indicate that groundwater is a significant contributor to stream discharge. Linear reservoir models show basin response times of up to 16 hours. The geophysical and hydrological evidence points toward two flow systems operating in the Babylon basin, those of flow through the fractured bedrock and flow through the talus and moraine complex. Understanding the hydrologic characteristics of alpine talus and moraine complexes and fractured bedrock is of great importance to increasing our knowledge of alpine hydrology. The results from this study will enable the estimation of hydrologic parameters of these geologic media and provide valuable information for the predictive modelling of mountain streams.

Muir, D. L.; Hayashi, M.; Bentley, L. R.

2009-05-01

31

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

OpenAIRE

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

32

Simultaneous fracture of the ankle and talus associated with ruptured tibialis posterior tendon.  

Science.gov (United States)

A 45-year-old woman involved in a motor vehicle accident sustained a fracture of the medial malleolus and a fracture of the neck of the talus. Open reduction and internal fixation of the fractures were achieved through an anteromedial approach. Intraoperatively, the tibialis posterior tendon was found to be ruptured and retracted. The tendon was reapproximated and repaired. The patient developed an inversion deformity of the ankle, which required release of the tibialis posterior tendon and correction of the deformity using the Ilizarov fixation device. Twelve months after the injury, the patient had 45 degrees of plantar flexion and 15 degrees of dorsiflexion of the ankle; subtalar motion was 25 degrees of eversion and 35 degrees of inversion. Radiographs showed healing of all fractures with minimal degenerative changes of the ankle joint and absence of avascular necrosis of the talus. PMID:7663957

Ebraheim, N A; Wong, F Y

1995-05-01

33

Dysplasia Epiphysealis Hemimelica (Trevor Syndrome) of Talus in a 21-Year Old Woman; Case Report  

OpenAIRE

Dysplasia epiphysealis hemimelica is a rare nonhereditary epiphyseal disease that mimics synovial chondromatosis and osteochondroma of the joints. The disease mainly involves long bones of the lower extremities and tarsal bones. Herein we report 21-year old woman who presented with pain and limited range of ankle motion, who underwent surgical excision of talus exostosis after preoperative imaging and careful planning. after that she was discharged and her problem improved and she...

Sadeghifar, Amir R.; Heshmati, Afshin Ahmadzadeh

2014-01-01

34

Tertiary osteochondral defect of the talus treated by a novel contoured metal implant  

OpenAIRE

The primary treatment of most osteochondral defects of the talus is arthroscopic debridement and bone marrow stimulation. There is no optimal treatment for large lesions or for those in which primary treatment has failed. We report a 20-year-old female patient with persistent symptoms after two previous arthroscopic procedures. Computed tomography showed a cystic defect of the medial talar dome, sized 17 × 8 × 8 mm. The patient was treated with a novel contoured metal implant. At 1 and...

Bergen, Christiaan J. A.; Reilingh, Mikel L.; Dijk, C. Niek

2011-01-01

35

Diagnosis of aseptic necrosis of the talus by bone scintigraphy. Case report  

International Nuclear Information System (INIS)

Bone scintigraphy is a very useful technique for detection of aseptic necrosis. We have used this diagnostic tool in a patient to detect aseptic necrosis of the talus, a common complication stemming from foot injuries. The scintigraphic pattern is rather typical and antedates any other radiographic changes. This technique appears to be very useful for diagnosis and follow-up of aseptic necrosis occurring during talar injuries

36

Free chondral fragement involving the lateral trochlear ridge of the talus in a dog  

International Nuclear Information System (INIS)

A saucer-shaped defect involving the lateral trochlear ridge of the talus and a radiopaque joint fragment were evident on radiographs of the left tarsus in a 6-month-old Rottweiler. Surgical treatment involved removal of the joint fragment and debridement of the defect. Histologic interpretation of the specimen was a chondral fragment. It is important to realize the possibility of a lesion in the location described, as this may be an additional site for osteochondrosis dissecans of the canine tarsus

37

Groundwater flow and storage within an alpine meadow-talus complex  

Science.gov (United States)

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 (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.

McClymont, A. F.; Hayashi, M.; Bentley, L. R.; Muir, D.; Ernst, E.

2010-06-01

38

Fracture of the lateral process of the talus: appearance at MR imaging and clinical significance  

Energy Technology Data Exchange (ETDEWEB)

The case of a 59-year-old man with chronic lateral ankle pain following an inversion injury is presented. MR imaging performed to evaluate for soft tissue injury revealed an unsuspected fracture of the lateral process of the talus. The patient underwent surgical exploration of the fracture with debridement of adjacent loose bodies and is currently undergoing aggressive physical rehabilitation. (orig.) With 3 figs., 21 refs.

Sanders, T.G.; Morrison, W.B. [Department of Radiology, Wilford Hall United States Air Force Medical Center, Lackland AFB, TX (United States); Ptaszek, A.J. [Department of Orthopaedic Surgery, Foot and Ankle Service, Wilford Hall United States Air Force Medical Center, Lackland AFB, Texas (United States)

1999-04-01

39

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.))

40

Idiopathic transient osteoporosis of the talus: a cause for unexplained foot and ankle pain.  

Science.gov (United States)

A 53-year-old woman was investigated for several neoplastic, inflammatory, and infective conditions for her left foot, and ankle pain associated with swelling, which she developed unexpectedly without history of trauma or infection. Gross osteopenia in the talus raised the possibilities of several differential diagnoses, but a magnetic resonance imaging scan showed diffuse bone marrow edema in the talus. With negative infective and inflammatory markers, the condition was ultimately labeled as "transient osteoporosis." She was reassured and followed up regularly. At the end of 12 months, she was completely asymptomatic, and her radiograph and magnetic resonance images showed significant improvement, with a normal-appearing talus and ankle joint, and there was complete resolution of bone marrow edema. Although "transient osteoporosis" of the foot is an uncommon condition, clinicians should be aware of this. Unexplained foot pain, with osteopenic bone and diffuse bone marrow edema on magnetic resonance imaging scan, is a feature of this condition. However, the diagnosis is established once other causes are excluded. The condition is self-limiting, and watchful expectancy of a normal recovery is the mainstay of treatment. PMID:22608351

Limaye, Rajiv; Tripathy, Sujit Kumar; Pathare, Sanjay; Saeed, Kamran

2012-01-01

41

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

42

Treatment of bone marrow edema of the talus with pulsed electromagnetic fields outcomes in six patients.  

Science.gov (United States)

Background : Bone marrow edema (BME) of the talus is a rare, mostly self-limiting cause of foot and ankle pain. We sought to investigate in patients with idiopathic BME of the talus the effectiveness of pulsed electromagnetic fields and to determine the effect of this therapy on magnetic resonance imaging findings. Methods : Six patients with BME of the talus confirmed by magnetic resonance imaging were enrolled. Pain was quantified with a visual analog scale from 0 (no pain) to 10 (the worst pain imaginable). The clinical outcome was assessed using the American Orthopaedic Foot and Ankle Society scoring system. Treatment consisted of pulsed electromagnetic field stimulation 8 h/d for 30 days. The device used generated pulses 1.3 milliseconds in duration, with a frequency of 75 Hz and a mean ± SD induced electric field of 3.5 ± 0.5 mV. Results : The mean American Orthopaedic Foot and Ankle Society score improved from 59.4 (range, 40-66) before treatment to 94 (range, 80-100) at the last follow-up. The visual analog scale score decreased significantly from 5.6 (range, 4-7) before treatment to 1 (range, 0-2) at the last follow-up. Magnetic resonance imaging showed that BME improved after 1 month of treatment and resolved completely within 3 months in 5 patients, with normal signal intensity and no signs of progression to avascular necrosis. Conclusions : A significant reduction in BME area was associated with a significant decrease in pain within 3 months of beginning treatment. PMID:25675223

Martinelli, Nicolò; Bianchi, Alberto; Sartorelli, Elena; Dondi, Alessandra; Bonifacini, Carlo; Malerba, Francesco

2015-01-01

43

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

International Nuclear Information System (INIS)

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

44

Epidemiological study on talus fractures / Estudo epidemiológico das fraturas do tálus  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in portuguese Objetivo: Analisar as características dos indivíduos e das lesões encontradas em pacientes com fraturas de tálus. Métodos: Análise retrospectiva dos pacientes internados no Instituto de Ortopedia e Traumatologia do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo de 200 [...] 6 a 2011 com fratura de tálus. Foram estudados parâmetros associados ao perfil do paciente e fatores de risco, características da fratura, dados do tratamento e complicações agudas. Resultados: A análise dos 23 casos mostrou que os homens foram mais afetados do que as mulheres, com uma relação de 4,8:1. O mecanismo de trauma mais frequente foram os acidentes de trânsito, seguido pelas quedas de altura. O tipo de fratura mais frequente foi a do colo do tálus, com 17 casos. Dos 23 casos, sete apresentavam luxação peritalar no momento da apresentação, quatro tinham fratura exposta e 11 apresentavam outras fraturas associadas. O tempo médio entre o trauma e o tratamento definitivo foi de seis dias, enquanto o tempo médio de permanência hospitalar foi de 11 dias. Houve três pacientes que apresentaram complicações pós-operatórias agudas. Conclusão: A fratura do tálus foi mais comum na região do colo e mais frequente em jovens do gênero masculino que sofreram traumatismos de alta energia. Em quase metade dos casos houve fraturas associadas e o tempo de permanência hospitalar foi de 11 dias. Abstract in english Objective: To analyze the characteristics of patients with talus fractures and the injuries that they present. Methods: Retrospective analysis on patients hospitalized in the Institute of Orthopedics and Traumatology, Hospital das Clínicas, School of Medicine of the University of São Paulo, betwe [...] en 2006 and 2011, with talus fractures. Patient profile parameters, risk factors, fracture characteristics, treatment data and acute complications were analyzed. Results: Analysis on 23 cases showed that men were more affected than women, with a ratio of 4.8:1. The most frequent trauma mechanism was traffic accidents, followed by falls from a height. The most frequent type of fracture was at the neck of the talus, with 17 cases. Among the 23 cases, seven had peritalar dislocation at the time of presentation, four had exposed fractures and 11 presented other associated fractures. The mean length of time between the trauma and the definitive treatment was six days, while the mean length of hospital stay was 11 days. Three patients presented acute postoperative complications. Conclusion: Talus fractures occurred most commonly in the region of the talar neck and most frequently in young males who suffered high-energy trauma. In almost half of the cases, there were other associated fractures. The length of hospital stay was 11 days.

Marcos Hideyo, Sakaki; Guilherme Honda, Saito; Rafael Garcia de, Oliveira; Rafael Trevisan, Ortiz; Jorge dos Santos, Silva; Túlio Diniz, Fernandes; Alexandre Leme Godoy dos, Santos.

2014-07-01

45

Dysplasia Epiphysealis Hemimelica (Trevor Syndrome of Talus in a 21-Year Old Woman; Case Report  

Directory of Open Access Journals (Sweden)

Full Text Available Dysplasia epiphysealis hemimelica is a rare nonhereditary epiphyseal disease that mimics synovial chondromatosis and osteochondroma of the joints. The disease mainly involves long bones of the lower extremities and tarsal bones. Herein we report 21-year old woman who presented with pain and limited range of ankle motion, who underwent surgical excision of talus exostosis after preoperative imaging and careful planning. after that she was discharged and her problem improved and she have no problem in three year follow up .pathologic examination of specimen confirm the diagnosis.

Amir R Sdeghifar

2014-03-01

46

Dysplasia epiphysealis hemimelica (trevor syndrome) of talus in a 21-year old woman; case report.  

Science.gov (United States)

Dysplasia epiphysealis hemimelica is a rare nonhereditary epiphyseal disease that mimics synovial chondromatosis and osteochondroma of the joints. The disease mainly involves long bones of the lower extremities and tarsal bones. Herein we report 21-year old woman who presented with pain and limited range of ankle motion, who underwent surgical excision of talus exostosis after preoperative imaging and careful planning. after that she was discharged and her problem improved and she have no problem in three year follow up. pathologic examination of specimen confirm the diagnosis. PMID:25207317

Sadeghifar, Amir R; Heshmati, Afshin Ahmadzadeh

2014-03-01

47

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

48

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

49

Osteochondrosis of the lateral trochlear ridge of the talus in seven Rottweiler dogs  

International Nuclear Information System (INIS)

Eleven lesions of osteochondrosis in the lateral trochlear ridge of the talus were diagnosed in seven young Rottweiler dogs. Diagnosis was based on clinical and radiographic evaluations. Defects in the lateral trochlear ridge and osteochondral fragments arising from the dorsal and proximal margins of the ridge were visible radiographically. The dorsal 45 degrees lateral-plantaromedial oblique (D45 degrees L-P1MO) projection was the most useful in identifying the lesions. Exploratory arthrotomies were performed in six affected tarsi. In three cases, histologic examination revealed mineralized osteochondral fragments consistent with a diagnosis of osteochondrosis

50

Accumulation of Lead (Pb in the Talus Lichenes Contained in Mahogany Tree Stands of Roadside of Medan City  

Directory of Open Access Journals (Sweden)

Full Text Available This study reports on the accumulation of lead (Pb in the talus Lichenes found on roadside stands of mahogany trees in the city of Medan, North Sumatra, Indonesia. Samples were taken by purposive, ie location based on the level of traffic density with different air pollution. Pb analysis was performed using Atomic Absorption Spectroscopy (AAS. Identified as many as 8 kinds of Lichens with 2 types, namely talus Crustose and foliose. Type of Lepraria incana and Pertusaria amara, which is found in the three study sites belonging to the cosmopolitan types. Pb accumulated in the talus Pertusaria amara ranged from 5.23 to 15.07 ppm. Being on Lepraria incana ranged 1.19 to 4.88 ppm. Pertusaria amara much larger than the Lepralia incana, have potential as bio-indicators of resistance. Lichenes Pb correlation with traffic density showed Pertusaria amara has a very high level and significant correlation compared with other types.

Ashar Hasairin

2014-12-01

51

Why allograft reconstruction for osteochondral lesion of the talus? The osteochondral autograft transfer system seemed to work quite well.  

Science.gov (United States)

Osteochondral lesions of the talus (OCLT) are a challenging entity despite the advancements that have been made to treat focal deficits of articular cartilage. Both autograft and allograft reconstruction have had documented success in the treatment of OLCT. Universal availability and known chondrocyte viability makes the osteochondral autograft transfer system (OATS) an excellent option for recurrent, deep, or moderate defects. For defects with a large diameter, large cystic component, or heavily involving the shoulder of the talus, an allograft provides an excellent option. This article focuses on the efficacy and determination of the most appropriate graft reconstruction: allograft reconstruction or OATS. PMID:23465951

Kadakia, Anish R; Espinosa, Norman

2013-03-01

52

Estimates of slope erosion intensity utilizing terrestrial laser scanning  

Science.gov (United States)

Despite the large variety of methods for estimating slope erosion intensity, it is still difficult to obtain accurate erosion rates. Therefore, our goal was to develop a method to provide accurate estimates of sheet and rill erosion intensities, and evaluate denudation quantities due to abrasion, landslides and talus processes using a high-precision laser scanning system (Trimble® GX). Differential maps between all stages of surveying and TIN-models were built directly on point clouds in "Trimble® RealWorks" software. Inspection and cross-section tools were used for detailed study of ground movements on the slope surface and the development of linear erosion forms. A new method for accurate estimates of the erosion has been developed using terrestrial laser scanning techniques. It makes it possible to assess the denudation-accumulation balance on erosive slopes, determine the dynamics of the volume of material moved on different parts of the slope in various surface runoff events, and identify spatial regularities forming rill washouts.

Usmanov, B.; Yermolaev, O.; Gafurov, A.

2015-03-01

53

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

54

Comminuted fracture of the calcaneus associated with subluxation of the talus.  

Science.gov (United States)

Two cases of complex fracture dislocation of the calcaneus having an unusual pattern of injury are described. The cases exhibit the following special characteristics: (1) fracture dislocation of the calcaneus where the primary fracture line separates the calcaneus into an anteromedial fragment that maintains its normal relationship to the talus and a posterolateral fragment that is dislocated from the subtalar joint. This posterolateral fragment moves laterally and lies adjacent to the fibula; (2) a secondary fracture line separating the lateral portion of the posterior facet from the tuberosity of the calcaneus. Both fragments are dislocated from their normal anatomical position; (3) talar tilt as shown on AP view of the ankle caused by inversion of the talus due to rupture of the lateral collateral ligament. Also, the posterolateral fragments impinging on the fibula pushes the heel downward and contributes to the talar tilt; (4) involvement of the calcaneocuboid joint; (5) dislocation of the peroneal tendons. This fracture pattern is unusual and has not been described before. Recognition of this unusual injury with subsequent and proper management may prevent major disability to the patient. Conservative treatment by casting or early range of motion is contraindicated. Closed reduction should be attempted immediately, and if not successful, a lateral approach with open reduction and internal fixation is the treatment of choice for this complex injury. PMID:8406256

Ebraheim, N A; Savolaine, E R; Paley, K; Jackson, W T

1993-09-01

55

The shape and presentation of the Catarrhine talus: a geometric morphometric analysis.  

Science.gov (United States)

The distal component of the talo-crural joint, the talus, was compared, using geometric morphometrics, in 219 specimens from nine extant taxa to identify differences in shape and the factors influencing them. The specimens were laser scanned, digitally reconstructed, and landmarked. The whole talus, proximal and distal articular facet subgroups were analyzed using Generalized Procrustes analysis, linear regression, principal component analysis, analysis of percent variance, dot-product vector analysis, and pair-wise permutation tests to evaluate shape, and were visualized by TPS deformation of an exemplar surface. Significant percentages of shape variation among taxa were due to body mass, talar size, superfamily, and substrate preference. Shape and presentational morphology associated with these factors were documented, along with the similarities and differences among individual taxa. Nearly all taxa were significantly different in overall, proximal and distal shapes. The most important factors influencing whole talar shape were log centroid size and substrate preference. Substrate preference was also the most important factor defining proximal articular morphology and unrelated to other factor such as mass, while distal articular morphology was influenced by superfamily (head angle and shape). Results demonstrated that substrate preference and superfamily significantly influenced distal presentation, while substrate preference influenced proximal articular shape. PMID:23580472

Turley, Kevin; Frost, Stephen R

2013-06-01

56

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

Science.gov (United States)

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

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

2013-12-01

57

Slopes of Tilings  

CERN Document Server

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

Jeandel, Emmanuel

2010-01-01

58

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

OpenAIRE

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

59

Retrograde Percutaneous Drilling for Osteochondritis Dissecans of the Head of the Talus: Case Report and Review of the Literature.  

Science.gov (United States)

Osteochondral lesions of the talus might be a more common cause of pain than previously recognized, especially among those involved in athletic activities. However, the location of an osteochondral lesion on the talar head is much less common than such lesions localized to the dome of the talus and can pose diagnostic difficulties. We present the case of a 14-year-old soccer player who complained of longstanding pain in his left foot. After unsuccessful conservative treatment consisting of rest and bracing, he was ultimately treated with retrograde percutaneous drilling of the talar head performed by a medial approach. This was followed by casting and non-weightbearing for 6 weeks, after which physical therapy was undertaken. He was able to return to full activity and remained asymptomatic during a 5-year observation period. Although rare, osteochondritis dissecans of the talar head should be considered in young athletes with persistent foot pain that is unresponsive to reasonable therapy. PMID:25459089

Corominas, Laura; Sanpera, Ignacio; Masrouha, Karim; Sanpera-Iglesias, Julia

2014-10-31

60

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

61

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

62

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

International Nuclear Information System (INIS)

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.)

63

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

64

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

65

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

66

Infiltration into pyroclastic slopes  

Science.gov (United States)

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

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

2012-04-01

67

Slope stability - quick testing  

Energy Technology Data Exchange (ETDEWEB)

The paper discusses methods for determining slope stability in surface brown coal mines. The Fellenius method for determining safety index of slopes is described. Two versions of the method are compared: the initial version used for stability assessment of slopes which consist of homogenous rocks without water influx and the modified version used when a slope consists of a number of layers with differing physical properties and when water influx complicates stability conditions. In the modified version of the Fellenius method calculation procedure is repeated for each rock layer. A combined method for determining slope stability of spoil banks with the bottom consisting of loose plastic rock material is presented. Sliding planes in the plastic bottom of a spoil bank are shown in two schemes. Equations used in each of the versions of the Fellenius method are derived. Practical use of the method is explained. Examples of using the Fellenius method for strata control in brown coal surface mines are given. Recommendations for use of the optimum calculation method considering stratification of rock strata, water conditions and water influx are made. (3 refs.)

Sozanski, J.

1982-01-01

68

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

69

Alternative diagenetic models for cretaceous talus deposits, Deep Sea Drilling Project Site 536, Gulf of Mexico: Chapter 8 in Initial reports of the Deep Sea Drilling Project  

Science.gov (United States)

Talus deposits recovered from Site 536 show evidence of aragonite dissolution, secondary porosity development, and calcite cementation. Although freshwater diagenesis could account for the petrographic features of the altered talus deposits, it does not uniquely account for isotopic or trace-element characteristics. Also, the hydrologic setting required for freshwater alteration is not easily demonstrated for the Campeche Bank. A mixing-zone model does not account for the available trace-element data, but does require somewhat less drastic assumptions about the size of the freshwater lens. Although a seawater (bottom-water) alteration model requires no hydrologic difficulties, unusual circumstances are required to account for the geochemical characteristics of the talus deposits using this model.

Halley, Robert B.; Pierson, B. J.; Schlager, Wolfgang

1984-01-01

70

Percutaneous osteoplasty for the treatment of a painful osteochondral lesion of the talus: a case report and literature review.  

Science.gov (United States)

An osteochondral lesion of the talus (OLT) is a lesion involving the talar articular cartilage and its subchondral bone. OLT is a known cause of chronic ankle pain after ankle sprains in the active population. The lesion causes deep ankle pain associated with weight-bearing, impaired function, limited range of motion, stiffness, catching, locking, and swelling. There are 2 common patterns of OLTs. Anterolateral talar dome lesions result from inversion and dorsiflexion injuries of the ankle at the area impacting against the fibula. Posteromedial lesions result from inversion, plantar flexion, and external rotation injuries of the ankle at the area impacting against the tibial ceiling of the ankle joint. Early diagnosis of an OLT is particularly important because the tibiotalar joint is exposed to more compressive load per unit area than any other joint in the body. Failure of diagnosis can lead to the evolution of a small, stable lesion into a larger lesion or an unstable fragment, which can result in chronic pain, joint instability, and premature osteoarthritis. A 43-year-old man, with a history of ankle sprain one year previously, visited our pain clinic for continuous right ankle pain after walking or standing for more than 30 minutes. There was a focal tenderness on the posteromedial area of the right talus. Imaging studies revealed a posteromedial OLT classified as having a geode form according to the FOG (fractures, osteonecroses, geodes) radiological classification and categorized as a stage 2a lesion on magnetic resonance imaging. The patient was scheduled for aspiration and osteoplasty with hydroxyapatite under arthroscopic and fluoroscopic guidance. A 26-gauge needle was inserted to infiltrate local anesthetics into the skin over the cyst and ankle joint. An arthroscope was placed into the joint to approach the OLT. The arthroscopic view showed that there was no connection between the OLT and the cyst of the talus body. A 13-gauge bone biopsy needle was inserted into the cyst, and aspiration was performed. Aspirated fluid from the cyst was originally white and clear; however, it changed to a blood-tinged, reddish color due to mixing with the incisional blood. After aspiration, contrast medium was injected, and the shape of the spread was observed. Bone cement comprising hydroxyapatite was injected to fill the bone defect of the cyst. A 1.5 mL volume of cement was injected into the talus under vigilant fluoroscopic and arthroscopic monitoring to prevent its dissemination into the joint. There was no cement leakage into the vessels or articular space. Postoperative fluoroscopy and computed tomography images showed bone cement filling of the defect. In the present case, arthroscopic and fluoroscopic guidance was used for aspiration of an OLT and for performing percutaneous osteoplasty with hydroxyapatite for one defect; this treatment decreased pain upon weight bearing and enabled a return to work without any restrictions one week after the procedure. The purpose of this report was to highlight the presence of OLT in chronic ankle pain and to review its management strategies. PMID:22996869

Seo, Sung-Suk; Park, Joo-Yeon; Kim, Hae-Jin; Yoon, Ji-Wook; Park, Sang-Hyun; Kim, Kyung-Hoon

2012-01-01

71

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 < 0.0001). Dislocation of the talonavicular and calcaneocuboid joints was completely reduced in 22 (70.9%) and 29 (93.6%) of feet, respectively. Three children (five feet) underwent further surgery at a mean of 8.5 years post-operatively, three with pes planovalgus and two in whom the deformity had been undercorrected. No child developed avascular necrosis of the talus. Midtarsal joint release and open reduction is a satisfactory procedure, which may provide better results than peritalar release. Complications include the development of pes planovalgus and persistent dorsal subluxation of the talonavicular joint. PMID:24891587

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

2014-06-01

72

Human talus bones from the Middle Pleistocene site of Sima de los Huesos (Sierra de Atapuerca, Burgos, Spain).  

Science.gov (United States)

Here we present and describe comparatively 25 talus bones from the Middle Pleistocene site of the Sima de los Huesos (SH) (Sierra de Atapuerca, Burgos, Spain). These tali belong to 14 individuals (11 adult and three immature). Although variation among Middle and Late Pleistocene tali tends to be subtle, this study has identified unique morphological characteristics of the SH tali. They are vertically shorter than those of Late Pleistocene Homo sapiens, and show a shorter head and a broader lateral malleolar facet than all of the samples. Moreover, a few shared characters with Neanderthals are consistent with the hypothesis that the SH population and Neanderthals are sister groups. These shared characters are a broad lateral malleolar facet, a trochlear height intermediate between modern humans and Late Pleistocene H. sapiens, and a short middle calcaneal facet. It has been possible to propose sex assignment for the SH tali based on their size. Stature estimates based on these fossils give a mean stature of 174.4 cm for males and 161.9 cm for females, similar to that obtained based on the long bones from this same site. PMID:23706407

Pablos, Adrián; Martínez, Ignacio; Lorenzo, Carlos; Gracia, Ana; Sala, Nohemi; Arsuaga, Juan Luis

2013-07-01

73

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

74

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

75

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

76

Slope Estimation from ICESat/GLAS  

OpenAIRE

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 ...

Craig Mahoney; Natascha Kljun; Los, Sietse O.; Laura Chasmer; Hacker, Jorg M.; Christopher Hopkinson; North, Peter R. J.; Rosette, Jacqueline A. B.; Eva van Gorsel

2014-01-01

77

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

78

High slope waste dumps – a proven possibility  

Directory of Open Access Journals (Sweden)

Full Text Available This paper is an overview of dumping operations on High Slope Waste Dump at Veliki Krivelj open pit copper mine, RTB Bor, Serbia. The High Slope Waste Dump in Bor is the highest single slope waste dump in the world with the slope height of 405 m. The paper gives the basics and limitations of the designed dumping technology, the redesigned technology, gives an overview of the 13 year long operation and gathered experiences and addresses the main issues of dumping operations in high slope conditions as well as the present condition of the High Slope Waste Dump.

Igor Svrkota

2013-11-01

79

A simple limit for slope instability  

CERN Document Server

Ross and Thomas have shown that subschemes can K-destabilise polarised varieties, yielding a notion known as slope (in)stability for varieties. Here we describe a special situation in which slope instability for varieties (for example of general type) corresponds to a slope instability type condition for certain bundles, making the computations almost trivial.

Stoppa, J

2009-01-01

80

High slope waste dumps – a proven possibility  

OpenAIRE

This paper is an overview of dumping operations on High Slope Waste Dump at Veliki Krivelj open pit copper mine, RTB Bor, Serbia. The High Slope Waste Dump in Bor is the highest single slope waste dump in the world with the slope height of 405 m. The paper gives the basics and limitations of the designed dumping technology, the redesigned technology, gives an overview of the 13 year long operation and gathered experiences and addresses the main issues of dumping operations in high slope condi...

Igor Svrkota; Radoje Pantovi?; Miodrag Žiki?; Saša Stojadinovi?; Dejan Petrovi?

2013-01-01

81

Slope optimization by a priori integration methods  

Energy Technology Data Exchange (ETDEWEB)

Analyzes use of apriori integration methods for control of slope stability in deep coal surface mines and control of slope stability of spoil banks. Computer codes and algorithms used for slope stability control are analyzed. The following models are used in the integration methods: Petterson's model, model of Fellenius (power pressure effect), the modified Bishop's model, a model considerng effects of ground water, a model considering the streaming water effect. Behavior of stability fields is evaluated. Similarities of simple slopes are discussed. Effects of earthquakes on slope stabilty are also considered. 50 refs.

Prochazka, P. (Czechoslovak Academy of Sciences, Prague (Czechoslovakia). Institute of Geotechnics)

1990-01-01

82

Dip-slope and Dip-slope Failures in Taiwan - a Review  

Science.gov (United States)

Taiwan is famous for dip-slope and dip-slope slides. Dip-slopes exist at many places in the fold-and-thrust belt of Taiwan. Under active cutting of stream channels and man-made excavations, a dip-slope may become unstable and susceptible for mass sliding. Daylight of a bedding parallel clay seam is the most dangerous type for dip-slope sliding. Buckling or shear-off features may also happen at toe of a long dip-slope. Besides, a dip-slope is also dangerous for shallow debris slides, if the slope angle is between 25 to 45 degrees and the debris (colluvium or slope wash) is thick (>1m). These unstable slopes may slide during a triggering event, earthquake or typhoon storm; or even slide without a triggering event, like the 2010 Tapu case. Initial buckling feature had been found in the dip-slope of the Feitsui arch dam abutment after detailed explorations. Shear-off feature have also been found in dip-slope located in right bank of the Nahua reservoir after field investigation and drilling. The Chiufengerhshan slide may also be shear-off type. On the other hand, the Tapu, the Tsaoling slides and others are of direct slide type. The Neihoo Bishan slide is a shallow debris slide on dip-slope. All these cases demonstrate the four different types of dip-slope slide. The hazard of a dip-slope should be investigated to cover these possible types of failure. The existence of bedding parallel clay seams is critical for the stability of a dip-slope, either for direct slide or buckling or shear-off type of failure, and is a hot point during investigation. Because, the stability of a dip-slope is changing with time, therefore, detailed explorations to including weathering and erosion rates are also very necessary to ensure the long-term stability of a dip-slope.

Lee, C.

2011-12-01

83

Air pocket removal from downward sloping pipes:  

OpenAIRE

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

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

2012-01-01

84

Recurring Slope Lineae (RSL) in Equatorial Mars  

Science.gov (United States)

Here we report on RSL (possible water seeps) in equatorial regions of Mars, especially in the deep canyons of Valles Marineris (VM). They are active on north-facing slopes in northern spring and summer and on south-facing slopes in southern spring and summer, following the peak solar warming of these steep slopes. This equatorial activity places new constraints on the origin of RSL and has implications for future exploration.

McEwen, A. S.; Dundas, C.; Mattson, S.; Toigo, A.; Ojha, L.; Murchie, S.; Thomas, N.; Wray, J.; Byrne, S.; Chojnacki, M.

2013-09-01

85

Analysis of Slope Stability Using Limit Equilibrium  

OpenAIRE

In achievement of slope load sustainability using mixed soil technique, is considered acceptable the method for slope construction technology. This paper deals with evaluation of mixed soil technique for construction of stable slope and proves the soil capability by analysis of computerized modeling, the revealed result of investigation, the possibility of using nearest local material, reducing project cost, solving the construction geotechnical problem and accurate understanding of soil prop...

Abdoullah Namdar

2010-01-01

86

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

87

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

88

Effects of ongoing glacier retreat on steep valley-side drift slopes in the upper Bødalen valley, western Norway  

Science.gov (United States)

The general pattern and dominant trend of today's mountain glaciers worldwide is a retreat of glacier fronts, indicating a significant volume decrease. Negative glacier net balances have been recorded for all Scandinavian glaciers after 1999. The ongoing glacier retreat enlarges freshly exposed proglacial areas which are characterized by e.g. comparably higher intensities of denudational slope processes and higher sediment availability. This study focuses on influences of rapid glacier regression on contemporary surface processes acting on steep valley-side drift slopes in a characteristic steep, parabolic-shaped and glacier-fed valley (Bødalen,) located on the western side of the Jostedalsbreen ice cap in western Norway. The Bødalsbreen is one of the glaciers with the highest retreat rate in entire Norway. Since the Little Ice Age (LIA) glacier maximum advance (1750) the glacier retreated ca. 1.500 m, including 65 m of retreat within the period of 2001 to 2010. Due to this retreat large areas of unstable hillslopes covered by glacial deposits from the LIA lateral moraines have been exposed. A combination of high resolution terrestrial laser scanning (TLS) and a designed monitoring program has been applied to a selected hillslope site on the eastern flank of the Bødalsbreen. Three sequential terrestrial laser scans have been acquired in the summers of 2010, 2011 and 2012. The analysis of the three series of the high resolution point clouds enables (i) the detection of unstable slope areas, (ii) areas characterized primarily by erosion or deposition processes and (iii) to quantify volumes of mass transfers at the scanned site. The results from the TLS measurements are combined with the results from the monitoring program (installations in operation since 2009) which includes remote cameras for monitoring rapid mass movement events (avalanches, slush- and debris flows), stone tracer lines for measuring surface movements as well as temperature loggers both in rock walls and talus slopes for analyzing rock temperatures and mechanical weathering at this slope test site. In addition, slope wash traps for analyzing slope wash denudation have been installed and measurements of solute concentrations at small hillslope drainage creeks for investigating the role of chemical denudation have been conducted. Results show that after the retreat of the LIA glacier the lateral moraines still act as significant sediment sources, being mainly eroded along the moraine crest and within incised gullies. Most of the eroded material is reworked through secondary processes like rock falls, snow avalanches and debris-flows and slope wash processes. Regarding geomorphic mass transfers especially the freshly exposed (since the last 12 years) slope areas are comparable important as sediment is delivered through slope-channel coupling into the fluvial system (whereas the level of slope-channel coupling within the entire drainage basins is altogether rather limited). Further extension of these freshly exposed areas will increase sediment delivery rates from upper valley systems which is also expected to affect the downstream parts of the drainage basin.

Laute, Katja; Beylich, Achim A.; Oppikofer, Thierry

2013-04-01

89

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

90

Rock slopes and reservoirs - lessons learned  

Energy Technology Data Exchange (ETDEWEB)

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.

Moore, D.P. [BC Hydro, Burnaby, BC (Canada)

1999-07-01

91

Prótese do tornozelo híbrida em um caso de necrose avascular pós-traumática do tálus Hybrid ankle prosthesis in a case of post-traumatic avascular necrosis of the talus  

Directory of Open Access Journals (Sweden)

Full Text Available As fraturas do astrágalo originam frequentemente artrose pós-traumática tardia. Nestes casos, a utilização de próteses do tornozelo não cimentadas de última geração tem sido evitada pela presença de necrose avascular. Relatamos o caso de um paciente com 65 anos que se apresenta quatro anos após uma fratura do colo do astrágalo. Apresentava uma artrose do tornozelo dolorosa (escala AOFAS do retropé e tornozelo 19 e necrose avascular com colapso de toda a cúpula astragalina. Dada a extensão da necrose, foi decidido cimentar o componente protésico astragalino. Um ano após a cirurgia, o paciente apresenta bom resultado clínico e radiológico (escala AOFAS do retropé e tornozelo 87 e está satisfeito com o procedimento. Não temos conhecimento de nenhum relato semelhante na literatura.Talus fractures often lead to late post-traumatic arthrosis. In such cases, the use of latest generation, cementless prostheses has been hindered by the presence of avascular necrosis. We report the case of a 65-year-old patient who presented four years after a talus neck fracture. He had painful ankle arthrosis (AOFAS ankle-hindfoot score 19 and avascular necrosis, with collapse of the entire talar dome. Given the extent of the necrosis, it was decided to cement the talus prosthetic component. One year after the surgery, the patient shows good clinical and radiological results (AOFAS ankle-hindfoot score 87 and is satisfied with the procedure. We are not aware of any similar reports in the literature.

Ricardo Jorge Gomes de Sousa

2011-01-01

92

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

93

On the Slope of Fibred Surfaces  

CERN Document Server

Given a relatively minimal non locally trivial fibred surface f: S->B, the slope of the fibration is a numerical invariant associated to the fibration. In this paper we explore how properties of the general fibre of $f$ and global properties of S influence on the lower bound of the slope. First of all we obtain lower bounds of the slope when the general fibre is a double cover. We also obtain a lower bound depending as an increasing function on the relative irregularity of the fibration, extending previous results of Xiao. We construct several families of examples to check the assimptotical sharpness of our bounds.

Barja, M A; Barja, Miguel A.; Zucconi, Francesco

1999-01-01

94

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

95

Negative magnetoresistance slope in superconducting granular films  

Energy Technology Data Exchange (ETDEWEB)

Highlights: • The theory explaining recently observed negative magneto-resistance slope in ultra-thin YBa{sub 2}Cu{sub 2}O{sub 7??} films is developed. • Considering film as an array of the Josephson junctions, we solve the sine-Gordon equations including a viscosity term. • The solution yields a negative magneto-resistance slope setting in agreement with the experimental results. - Abstract: A phenomenological theory is developed to explain the recently observed negative magnetoresistance slope in ultra-thin granular YBa{sub 2}Cu{sub 2}O{sub 7??} films. Viewing this system as a two-dimensional array of extended Josephson junctions, we numerically solve the sine-Gordon equations including a viscosity term that increases linearly with the external field. The solution yields a negative magnetoresistance slope setting in at a field that is determined by the geometry and thus independent of temperature, in agreement with the experimental results.

Shapiro, Boris Ya., E-mail: shapib@mail.biu.ac.il; Shapiro, Irina; Levi, Daniel; Shaulov, Avner; Yeshurun, Yosef

2014-06-15

96

Taqulik Hepa: North Slope Natural Resources  

Science.gov (United States)

In this audio profile adapted from Raven Radio/KCAW, Alaska Native Taqulik Hepa, deputy director for the Department of Wildlife Management for the North Slope Borough, discusses resource management and subsistence living.

2008-11-04

97

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

98

Semistable periods of finite slope families  

OpenAIRE

We make use of the notion finite slope families to encode the local properties of the p-adic families of Galois representations in appeared in the work of Harris, Lan, Taylor and Thorne on the construction of Galois representations for (non-self dual) regular algebraic cuspidal automorphic representations of GL(n) over CM fields; this generalizes the original definition of finite slope families given by Skinner-Urban in their ICM talk. Our main result is to prove the analyti...

Liu, Ruochuan

2013-01-01

99

"Overburden stability of rock slopes in quarries"  

OpenAIRE

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

Oggeri, Claudio; Del Greco, Otello; Fornaro, Mauro

2000-01-01

100

Internal waves and temperature fronts on slopes  

OpenAIRE

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 intern...

Thorpe, S. A.; Lemmin, U.

1999-01-01

101

Rock slopes from mechanics to decision making  

OpenAIRE

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

Einstein, H. H.; Sousa, R. L.; Karam, K.; Manzella, Ire?ne; Kveldsvik, V.

2010-01-01

102

Outerplanar graph drawings with few slopes  

OpenAIRE

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

Knauer, Kolja; Micek, Piotr; Walczak, Bartosz

2012-01-01

103

Testing slope homogeneity in large panels  

OpenAIRE

This paper proposes a modified version of Swamy’s test of slope homogeneity for panel data models where the cross section dimension (N) could be large relative to the time series dimension (T). We exploit the cross section dispersion of individual slopes weighted by their relative precision. Using Monte Carlo experiments, we show that the test has the correct size and satisfactory power in panels with strictly exogenous regressors for various combinations of N and T. For autoregressive (AR)...

Pesaran, Mohammad Hashem; Yamagata, Takashi

2007-01-01

104

Up by upwest: Is slope like north?  

Science.gov (United States)

Terrain slope can be used to encode the location of a goal. However, this directional information may be encoded using a conceptual north (i.e., invariantly with respect to the environment), or in an observer-relative fashion (i.e., varying depending on the direction one faces when learning the goal). This study examines which representation is used, whether the sensory modality in which slope is encoded (visual, kinaesthetic, or both) influences representations, and whether use of slope varies for men and women. In a square room, with a sloped floor explicitly pointed out as the only useful cue, participants encoded the corner in which a goal was hidden. Without direct sensory access to slope cues, participants used a dial to point to the goal. For each trial, the goal was hidden uphill or downhill, and the participants were informed whether they faced uphill or downhill when pointing. In support of observer-relative representations, participants pointed more accurately and quickly when facing concordantly with the hiding position. There was no effect of sensory modality, providing support for functional equivalence. Sex did not interact with the findings on modality or reference frame, but spatial measures correlated with success on the slope task differently for each sex. PMID:24397309

Weisberg, Steven M; Nardi, Daniele; Newcombe, Nora S; Shipley, Thomas F

2014-10-01

105

Slope Estimation in Noisy Piecewise Linear Functions.  

Science.gov (United States)

This paper discusses the development of a slope estimation algorithm called MAPSlope for piecewise linear data that is corrupted by Gaussian noise. The number and locations of slope change points (also known as breakpoints) are assumed to be unknown a priori though it is assumed that the possible range of slope values lies within known bounds. A stochastic hidden Markov model that is general enough to encompass real world sources of piecewise linear data is used to model the transitions between slope values and the problem of slope estimation is addressed using a Bayesian maximum a posteriori approach. The set of possible slope values is discretized, enabling the design of a dynamic programming algorithm for posterior density maximization. Numerical simulations are used to justify choice of a reasonable number of quantization levels and also to analyze mean squared error performance of the proposed algorithm. An alternating maximization algorithm is proposed for estimation of unknown model parameters and a convergence result for the method is provided. Finally, results using data from political science, finance and medical imaging applications are presented to demonstrate the practical utility of this procedure. PMID:25419020

Ingle, Atul; Bucklew, James; Sethares, William; Varghese, Tomy

2015-03-01

106

Numerical Computation of Homogeneous Slope Stability  

Science.gov (United States)

To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS). PMID:25784927

Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong

2015-01-01

107

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

108

Numerical computation of homogeneous slope stability.  

Science.gov (United States)

To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS). PMID:25784927

Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong

2015-01-01

109

Geomorphologic mapping in the Ny Ålesund area (Svalbard Island, Norway) for the analysis of geomorphologic effects on rock slopes induced by glacier retreat in climate sensitive High Arctic regions  

Science.gov (United States)

The geomorphological effects of glacial retreat, rapidly changing Arctic environments and consequent local temporary permafrost melting are several types of glacial and periglacial landforms (pingos, solifluction, drumlins, etc.) but also debris and rock falls, alluvial fan and glacial outwash development and scarp/slopes retreat and evolution. In this work we have realized a geomorphologic map of rockfalls, landslides, alluvial fans and the slopes and scarps of steep mountainsides in the Ny Ålesund area (Svalbard Island, Norway) focused on the analysis of rock falls as geomorphological effects of glacier retreat, permafrost degradation and higher temperatures on slope processes. The investigation is based on geological and geomorphological field survey, and remote sensing and aerial photo interpretation, The Ny Ålesund area landscape is characterized by rugged non-vegetated mountains only partially covered by glaciers, with steep flanks and rock scarps; the scarps are formed by different types of rocks (intrusive and effusive igneous rocks, marine sedimentary rocks); this landscape is highly affected by debris and rock falls (from scarps and slopes) forming wide talus slopes and by alluvial fan and fluvial outwash (from glaciers), which make the surface sedimentary cover of the island together with rock glaciers and moraine deposits and locally fluvial deposits. The work is focused on the comprehension of the role of different factors in inducing rock falls, alluvial fans, slope/scarps evolution in high geomorphological sensitivity environments (i.e. glacial, periglacial or mountain) including: orography, lithology, rock fracturation, morphostructural setting, meteorological context. The conclusions focus on the possible geomorphological hazards affecting the Ny Ålesund area.

Miccadei, Enrico; Piacentini, Tommaso; Casacchia, Ruggero; Sparapani, Roberto

2014-05-01

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

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

112

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

Directory of Open Access Journals (Sweden)

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

Everton de Lima

2011-01-01

113

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 | Languages: English, 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.

114

Prótese do tornozelo híbrida em um caso de necrose avascular pós-traumática do tálus / Hybrid ankle prosthesis in a case of post-traumatic avascular necrosis of the talus  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Languages: English, Portuguese Abstract in portuguese As fraturas do astrágalo originam frequentemente artrose pós-traumática tardia. Nestes casos, a utilização de próteses do tornozelo não cimentadas de última geração tem sido evitada pela presença de necrose avascular. Relatamos o caso de um paciente com 65 anos que se apresenta quatro anos após uma [...] fratura do colo do astrágalo. Apresentava uma artrose do tornozelo dolorosa (escala AOFAS do retropé e tornozelo 19) e necrose avascular com colapso de toda a cúpula astragalina. Dada a extensão da necrose, foi decidido cimentar o componente protésico astragalino. Um ano após a cirurgia, o paciente apresenta bom resultado clínico e radiológico (escala AOFAS do retropé e tornozelo 87) e está satisfeito com o procedimento. Não temos conhecimento de nenhum relato semelhante na literatura. Abstract in english Talus fractures often lead to late post-traumatic arthrosis. In such cases, the use of latest generation, cementless prostheses has been hindered by the presence of avascular necrosis. We report the case of a 65-year-old patient who presented four years after a talus neck fracture. He had painful an [...] kle arthrosis (AOFAS ankle-hindfoot score 19) and avascular necrosis, with collapse of the entire talar dome. Given the extent of the necrosis, it was decided to cement the talus prosthetic component. One year after the surgery, the patient shows good clinical and radiological results (AOFAS ankle-hindfoot score 87) and is satisfied with the procedure. We are not aware of any similar reports in the literature.

Ricardo Jorge Gomes de, Sousa; Ricardo Pedro Ferreira Rodrigues, Pinto; Marta Maria Teixeira de Oliveira, Massada; Manuel Alexandre Negrais Pinho Gonçalves, Pereira; José Muras, Geada; Isabel Maria Gonçalves, Costa.

115

The logarithmic slope in diffractive DIS  

International Nuclear Information System (INIS)

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

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

Assessment of slope stability endangered by groundwater.  

Czech Academy of Sciences Publication Activity Database

Southampton : WIT Press, 2006 - (Brebbia, C.; Conti, M.; Tiezzi, E.), s. 709-718 ISBN 978-1-84564-048-4. [Ravage of Planet. Baryloche (AR), 12.12.2006-14.12.2006] R&D Projects: GA AV ?R IAA2119402 Institutional research plan: CEZ:AV0Z30460519 Keywords : physical and numerical modelling * slope stability * groundwater Subject RIV: JN - Civil Engineering

Procházka, P.; Tr?ková, Ji?ina

118

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.)

119

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

120

Recurring Slope Lineae in Valles Marineris, Mars  

Science.gov (United States)

Recurring slope lineae (RSL) are relatively low-albedo features up to a few m wide that extend down steep slopes from bedrock outcrops. Hundreds may form in rare locations, often associated with small channels. In the southern mid-latitudes, RSL appear and grow incrementally during the late southern spring through summer, and they favor equator-facing slopes--times and places with peak surface temperatures from ~250 to 300 K. RSL are recurring: they form and grow in the warm season, then fade and usually completely disappear in cold seasons. During the next warm season, similar but new features form and grow. For more, see McEwen et al., 2011, Science 333, 740. As of early 2012, 15 RSL sites had been confirmed between 52-32°S latitudes. Confirmation requires that we observe many new lineae forming at a site in more than one Mars year, distinguishing RSL from episodic dry mass wasting triggered by eolian, seismic, or impact activity. We have recently confirmed three sites in the equatorial region of Mars. Two of them are on the floor of Coprates Chasma and one is in central Valles Marineris, all near latitude 12S. They are on north-facing slopes and active in southern winter/northern summer (which may be the warmest season on these steep slopes, although in the southern hemisphere). The surface brightness temperatures from THEMIS remain in the range (>250 K) of the southern mid-latitude RSL sites when active, and the morphologies and geologic settings are also similar. We will continue monitoring these sites throughout the year, along with occasional monitoring of other candidate equatorial RSL sites. If RSL are due to flow of salty water, the equatorial sites may be of special interest for future exploration.

McEwen, A. S.; Dundas, C. M.; Byrne, S.; Mattson, S.; Ojha, L.; Schaefer, E.; Wray, J. J.

2012-12-01

121

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

Scientific Electronic Library Online (English)

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

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

2009-10-01

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

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

International Nuclear Information System (INIS)

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

124

Correlations between total cross sections and slopes  

Energy Technology Data Exchange (ETDEWEB)

We investigate correlations between the total cross section and the slope of the elastic differential cross section for proton-proton and antiproton-proton scattering at the highest energies. Based on the empirical behavior of these quantities as function of the energy, we select two different analytical parametrizations connecting them, and obtain the correlations through fits to the experimental data available. We present and discuss practical uses of extrapolations and interpolations of the results. In the former case we refer to the estimation of the proton-proton total cross sections from the proton-air cross sections (obtained from cosmic-ray experiments), and in the later case, we critically discuss the recent measurement of the slope parameter at the BNL RHIC at 200 GeV by the pp2pp Collaboration. (author)

Martini, A.F.; Menon, M.J.; Montanha, J. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Fisica

2004-03-01

125

Erosion dynamics following localized permafrost slope disturbances  

Science.gov (United States)

Slope 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

126

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

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

Wildlife response on the Alaska North Slope  

International Nuclear Information System (INIS)

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

129

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

130

Ocean processes at the Antarctic continental slope.  

Science.gov (United States)

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

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

2014-07-13

131

Ocean processes at the Antarctic continental slope  

OpenAIRE

The Antarctic continental shelves and slopes occupy relatively small areas, but, nevertheless, are important for global climate, biogeochemical cycling and ecosystem functioning. Processes of water mass transformation through sea ice formation/melting and ocean–atmosphere interaction are key to the formation of deep and bottom waters as well as determining the heat flux beneath ice shelves. Climate models, however, struggle to capture these physical processes and are unable to reproduce wat...

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

2014-01-01

132

Viscous liquid flow on Martian dune slopes  

CERN Document Server

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

Dobrovolskis, Anthony R

2014-01-01

133

Back analysis of reinforced soil slopes.  

Czech Academy of Sciences Publication Activity Database

Southampton : WIT Press, 2012 - (Mammoli, A.; Brebbia, C.), s. 423-432 ISBN 978-1-84564-602-8. ISSN 1743-3533. [Computational methods and experiments in material characterisation /3./. Material Characterisation 2007. Bologna (IT), 13.06.2007-15.06.2007] R&D Projects: GA AV ?R IAA2119402 Institutional research plan: CEZ:AV0Z30460519 Keywords : back analysis * numerical and experimental modelling * slopes Subject RIV: JM - Building Engineering

Procházka, P.; Tr?ková, Ji?ina

134

Edge waves along a sloping beach  

OpenAIRE

We construct a family of explicit rotational solutions to the nonlinear governing equations for water waves, describing edge waves propagating over a plane-sloping beach. A detailed analysis of the edge wave dynamics and of the run-up pattern is made possible by the use of the Lagrangian approach to the water motion. A graphical representation of the edge wave is also presented.

Constantin, Adrian

2001-01-01

135

Solutions for small slope pipeline lifting problems  

Energy Technology Data Exchange (ETDEWEB)

Two classes of submarine pipeline handling problems are considered, namely the lifting of a pipe with a free end for tie-in purposes, and the raising of part of a continuous line for hot-tapping or repair. If pipeline slopes are small (as is usual in seabed work), engineers' beam theory may be used in combination with a NewtonRaphson solution to locate the separation points between pipe and seabed. Key results are presented.

Hobbs, R.E.

1984-03-01

136

Geosensor Data Representation Using Layered Slope Grids  

Directory of Open Access Journals (Sweden)

Full Text Available Environmental monitoring applications are designed for supplying derived and often integrated information by tracking and analyzing phenomena. To determine the condition of a target place, they employ a geosensor network to get the heterogeneous sensor data. To effectively handle a large volume of sensor data, applications need a data abstraction model, which supports the summarized data representation by encapsulating raw data. For faster data processing to answer a user’s queries with representative attributes of an abstracted model, we propose such a data abstraction model, the Layered Slopes in Grid for Sensor Data Abstraction (LSGSA, which is based on the SGSA. In a single grid-based layer for each sensor type, collected data is represented by slope directional vectors in two layered slopes, such as height and surface. To answer a user query in a central monitoring server, LSGSA is used to reduce the time needed to extract event features from raw sensor data as a preprocessing step for interpreting the observed data. The extracted features are used to understand the current data trends and the progress of a detected phenomenon without accessing raw sensor data.

Keun Ho Ryu

2012-12-01

137

Geosensor data representation using layered slope grids.  

Science.gov (United States)

Environmental monitoring applications are designed for supplying derived and often integrated information by tracking and analyzing phenomena. To determine the condition of a target place, they employ a geosensor network to get the heterogeneous sensor data. To effectively handle a large volume of sensor data, applications need a data abstraction model, which supports the summarized data representation by encapsulating raw data. For faster data processing to answer a user's queries with representative attributes of an abstracted model, we propose such a data abstraction model, the Layered Slopes in Grid for Sensor Data Abstraction (LSGSA), which is based on the SGSA. In a single grid-based layer for each sensor type, collected data is represented by slope directional vectors in two layered slopes, such as height and surface. To answer a user query in a central monitoring server, LSGSA is used to reduce the time needed to extract event features from raw sensor data as a preprocessing step for interpreting the observed data. The extracted features are used to understand the current data trends and the progress of a detected phenomenon without accessing raw sensor data. PMID:23235448

Lee, Yongmi; Jung, Young Jin; Nam, Kwang Woo; Nittel, Silvia; Beard, Kate; Ryu, Keun Ho

2012-01-01

138

Stability of sulfur slopes on Io  

Science.gov (United States)

The mechanical properties of elemental sulfur are such that the upper crust of Io cannot be primarily sulfur. For heat flows in the range 100-1000 ergs/sq cm sec sulfur becomes ductile within several hundred meters of the surface and would prevent the formation of calderas with depths greater than this. However, the one caldera for which precise depth data are available is 2 km deep, and this value may be typical. A study of the mechanical equilibrium of simple slopes shows that the depth to the zone of rapid ductile flow strongly controls the maximum heights for sulfur slopes. Sulfur scarps with heights greater than 1 km will fail for all heat flows greater than 180 ergs/sq cm sec and slope angles greater than 22.5 deg. The observed relief on Io is inconsistent with that anticipated for a predominantly sulfur crust. However, a silicate crust with several percent sulfur included satisfies both the mechanical constraints and the observed presence of sulfur on Io.

Clow, G. D.; Carr, M. H.

1980-01-01

139

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

140

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

141

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

142

Topographic thresholds for plant colonisation on semiarid eroded slopes.  

Science.gov (United States)

In severely eroded areas, plant colonisation on steep slopes is limited by the action of strong erosive forces that interact with plants at early stages of plant establishment. The objective of this study was to understand the mechanism that controls spontaneous plant colonisation on highly eroded slopes in a semiarid badland area of East Spain by (i) determining topographic thresholds for plant colonisation, (ii) identifying the soil properties limiting to plant establishment and (iii) assessing whether colonising species have specific plant traits to cope with those limitations. We used slope angle and aspect as surrogates of erosion rate and water availability respectively. Since soil erosion and water availability can limit plant establishment and both interact in the landscape, we analysed variations in colonisation success with slope angle, as a function of slope aspect. Vegetation success was measured in terms of total vegetation cover and number of species in 156 different slopes. After determining slope angle thresholds, soil was sampled near the threshold values for soil analysis (nitrogen, phosphorous and CaCO3 contents and water holding capacity). Plant traits related to plant colonising capacity were analysed both in the pool of species colonising the steep slopes just below the threshold values and in the pool of species inhabiting the gentler slopes and absent from the steeper slopes just below the threshold. The identified slope angle threshold values for plant colonisation clearly decreased from North to South. No differences existed in soil properties neither among slope aspects at the slope angle threshold values nor between slope positions (just below and above the threshold) within slope aspect classes. This suggests that variations in the slope angle threshold between slope aspect classes result from differences in the colonising capacity of plants controlled by water availability. Long-distance dispersal, mucilage production and specific leaf area proved to be preferably associated with the pool of colonising species. These results may be useful in the perspective a more efficient ecological restoration of severely eroded semiarid ecosystems.

Bochet, E.; García-Fayos, P.; Poesen, J.

2009-04-01

143

Impact of slope gradient on soil surface features and infiltration on steep slopes in northern Laos  

Science.gov (United States)

It was recently demonstrated that, infiltration into mountain-tilled soils with highly stable microaggregates, increases with increasing slope gradient. In this work we investigate the processes that underpin this phenomenon by means of field experiments and modelling. The study area is located in northern Laos. Rainfall simulations were conducted in two 1-m 2 plots using a portable field simulator. The drop size distribution and kinetic energy were similar to that occurring on the occasion of tropical downpours. Soils exhibited a clay loam texture and very similar organic matter contents across experimental plots, but differed greatly in slope gradient (30% and 75%). Runoff water samples were collected at intervals ranging from 1 to 3 min, depending on the runoff intensity. Plots microtopography was measured before and after rainfall simulations using an automatic surface roughness meter on a 1-cm grid. High-resolution bulk density images were obtained from soil slices using a standard X-ray generator. Final infiltration rates of 6 and 21 mm h -1; soil detachment of 667 and 310 g m -2; surface lowering due to soil loss of 0.82 and 0.38 mm; surface lowering due to compaction of 1.21 and 0.90 mm; percentage area with sieving crust of 36% and 90%; percentage area with erosion crust of 63% and 0%; were obtained for the 30% and 75% slopes, respectively. Three main conclusions can be drawn from this work: (1) high intensity rainfall can rapidly transform soil surface features of steep bare soil; (2) on steeper slopes, the micro-relief tends to form micro-terraces much more pervious and less erodible than the ripple-like roughness that formed on gentler slopes; and (3) there was a more pronounced lowering of the soil surface due to compaction and denser microlayers on gentler slopes. The latter conclusion confirms the hypothesis that higher effective rainfall intensity is responsible for the formation of less permeable erosion crusts under 30% slope gradients while more permeable structural crusts develop under 75% slope gradients. The runoff results were modelled with the Green and Ampt model which accounts for time evolution of soil hydraulic conductivity. This modelling shows that soil is undoubtedly non homogeneous, evolves with time and that infiltration kinetics is slower and soil permeability greater for the 75% slope.

Ribolzi, O.; Patin, J.; Bresson, L. M.; Latsachack, K. O.; Mouche, E.; Sengtaheuanghoung, O.; Silvera, N.; Thiébaux, J. P.; Valentin, C.

2011-04-01

144

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

Directory of Open Access Journals (Sweden)

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

Suhaimi Jamaludin

2006-01-01

145

Mars Exploration Rover Landing Site Hectometer Slopes  

Science.gov (United States)

The Mars Exploration Rover (MER) airbag landing system imposes a maximum slope of 5 degrees over 100 m length-scales. This limit avoids dangerous changes in elevation over the horizontal travel distance of the lander on its parachute between the time of the last radar altimeter detection of the surface and the time the retro-rockets fire and the bridle to the airbags is cut. Stereo imagery from the MGS MOC can provide information at this length scale, but MOC stereo coverage is sparse, even when targeted to MER landing sites. Additionally, MGS spacecraft stability issues affect the DEMs at precisely the hectometric length-scale1. The MOLA instrument provides global coverage pulse-width measurements2 over a single MOLA-pulse footprint, which is about 100 m in diameter. However, the pulse spread only provides an upper bound on the 100 m slope. We chose another approach. We sample the inter-pulse root-mean-square (RMS) height deviations for MOLA track segments restricted to pixels of 0.1 deg latitude by 0.1 deg longitude. Then, under the assumption of self-affine topography, we determine the scale-dependence of the RMS deviations and extrapolate that behavior over the range of 300 m to 1.2 km downward to the 100 m scale. Shepard et al.3 clearly summarize the statistical properties of the RMS deviation (noting that it also goes by the name structure function, variogram or Allan deviation), and we follow their nomenclature. The RMS deviation is a useful measure in that it can be directly converted to RMS-slope for a given length-scale. We map the results of this self-affine extrapolation method for each of the proposed MER landing sites as well as Viking Lander 1 (VL1) and Pathfiner (MPF). In order of decreasing average hectometer RMS-slopes, Melas (about 4.5 degrees) > Elysium EP80 > Gusev > MPF > Elysium EP78 > VL1 > Athabasca > Isidis > Hematite (about 1 degree). We also map the scaling parameter (Hurst exponent); its behavior in the MER landing site regions is interesting in how it ties together the regional behavior of kilometer slopes (directly measured with MOLA) with the decameter and meter slopes (locally derived from stereo image analysis or radar scattering). 1Kirk, R. L., E. Howington-Kraus, and B. A. Archinal, Int. Arch. Photogramm. Remote Sens., XXVIII(B4), 476 (CD-ROM), 2001; Kirk, R. L., E. Howington-Kraus, and B. A. Archinal, Lunar Planet Sci., XXXIII, abs 1988, 2002. 2Garvin, J. B., and J. J. Frawley, Lunar Planet. Sci., XXXI, abs 1884, 2000. 3Shepard, M. K., R. A. Brackett, and R. E. Arvidson, J. Geophys. Res., 100, 11709-11718, 1995.; Shepard, M. K., et al., J. Geophys. Res., 106, 32777-32796, 2001.

Haldemann, A. F.; Anderson, F. S.

2002-12-01

146

A giant submarine slope failure on the northern insular slope of Puerto Rico  

Science.gov (United States)

A large amphitheater-shaped scarp, approximately 55 km across, was imaged on the northern insular slope of Puerto Rico using long-range sidescan sonar and bathymetric data. This scarp results from the removal of more than 1500 km3 of Tertiary strata. A review of seismic-reflection profiles, stratigraphic data, and subsidence models of the northern insular margin of Puerto Rico were used to infer that large-scale slope failure was induced by the tectonic oversteepening of the insular slope and was responsible for the formation of the scarp. The oversteepening probably was caused by the most recent episode of convergence of the Caribbean and North American plates, which began between approximately 4 and 2.5 m.y. ago. The Tertiary strata have been tilted approximately 4.5?? to the north in the last 4 m.y. ?? 1991.

Schwab, W.C.; Danforth, W.W.; Scanlon, K.M.; Masson, D.G.

1991-01-01

147

The British Geological Survey's 'Slope Dynamics' Project  

Science.gov (United States)

The aim of the British Geological Survey (BGS)'s ‘Slope Dynamics' project is to provide observational data to slope stability modelling and zoning based on factors of safety obtained from a combination of geotechnical, geomorphological and oceanographic models. The project has been monitoring since 2001 the progress of terrestrial and coastal landslides within 'soft rock' formations in the UK. Recently, field observatories have been set up to allow a variety of methods, some traditional and others novel, to be applied to actively unstable natural slopes in order to achieve a thorough understanding of the substrata, the mass movement processes within them and their relationship to the environment and environmental change. Monitoring has been carried out at six or twelve monthly intervals at test sites on the east coast of England (Holderness and Norfolk) and at Hollin Hill in North Yorkshire. A key part of the project makes use of innovative terrestrial LiDAR methods to produce repeated accurate 3-D models of the ground surface, which then enable ‘change models' of landslide movements to be determined. This work was started in 2001 and is continuing. The BGS currently has two Riegl terrestrial laser scanners: the long-range LPM-i800HA and the very-long-range LPM-2K; the former being equipped with a digital camera. The multiple scans are positioned in the national grid co-ordinate system using high resolution dGPS. Together, these allow accurate observations to be made in remote and exposed locations without the need for potentially dangerous direct access to the steeper more unstable slopes. The coastal test sites, which have exhibited recession rates of between 2m and 9m per year, allow rapid changes to be monitored. Inland active landslides are less common but more suited to instrumentation and long-term monitoring. Results to date have revealed the relationships between landslide style and geology, and also the patterns and time scales of characteristic cycles of mass movement at coastal sites.

Hobbs, Peter; Foster, Claire; Pearson, Stephen; Jones, Lee; Pennington, Catherine; Jenkins, Gareth; Gibson, Andrew; Cooper, Anthony; Freeborough, Katherine

2010-05-01

148

Solar dazzle reflected from sloping glazed facades  

Energy Technology Data Exchange (ETDEWEB)

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

Littlefair, P.J.

1987-04-01

149

Slope equalities for genus 5 surface fibrations  

CERN Document Server

K. Konno proved a slope equality for fibred surfaces with fibres of odd genus and general fibre of maximal gonality. More precisely he found a relation between the invariants of the fibration and certain weights of special fibres (called the Horikawa numbers). We give an alternative and more geometric proof in the case of a genus 5 fibration, under generality assumptions. In our setting we are able to prove that the fibre with positive Horikawa numbers are precisely the trigonal ones, we compute their weights explicitly and thus we exhibit explicit examples of regular surfaces with assigned invariants and Horikawa numbers.

Tenni, Elisa

2010-01-01

150

Slopes of eigencurves over boundary disks  

OpenAIRE

Let $p$ be a prime number. We study the slopes of $U_p$-eigenvalues on the subspace of modular forms that can be transferred to a definite quaternion algebra. We give a sharp lower bound of the corresponding Newton polygon. The computation happens over a definite quaternion algebra by Jacquet-Langlands correspondence; it generalizes a prior work of Daniel Jacobs who treated the case of $p=3$ with a particular level. In case when the modular forms have a finite character of...

Wan, Daqing; Xiao, Liang; Zhang, Jun

2014-01-01

151

Outerplanar graph drawings with few slopes  

CERN Document Server

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

Knauer, Kolja; Walczak, Bartosz

2012-01-01

152

Slope stability analysis of Valles Marineris, Mars  

Science.gov (United States)

Valles Marineris (VM) in the equatorial area of Mars exhibits several gravitational failures which resulted in a series of large landslides up to several hundred cubic kilometers in volume. Questions arise as to forces at play and rock strength in the stability of the walls of VM. In this work we address the stability analysis of the walls of VM by considering the strength of the materials of the chasma walls and the causes of landslides. Using finite element calculations and the limit analysis upper bound method, we explore the range of cohesion and friction angle values associated to realistic failure geometries, and compare predictions with the classical Culmann's wedge model. Our analysis is based both on synthetic, simplified slope profiles and also on the real shape of the walls of VM taken from the MOLA topographic data. Validation of the calibrated cohesion and friction angle values is performed by comparing the computed unstable cross sectional areas with the observed pre- and post-failure profiles and estimated failure surface geometry. This offers a link between rock mass properties, slope geometry and volume of the observed failure. Pseudo-static seismic analyses generated another set of dimensionless charts. Our pseudo-static analyses show that low seismicity events induced by meteoroids impacts compatible with the size of craters could be a cause for some of the observed landslides if poor rock properties for VM is assumed.

Vittorio De Blasio, Fabio; Battista Crosta, Giovanni; Castellanza, Riccardo; Utili, Stefano

2013-04-01

153

Slope evolution of GRB correlations and cosmology  

CERN Document Server

Gamma -ray bursts (GRBs) observed up to redshifts $z>9.4$ can be used as possible probes to test cosmological models. Here we show how changes of the slope of the {\\it luminosity $L^*_X$ -break time $T^*_a$} correlation in GRB afterglows, hereafter the LT correlation, affect the determination of the cosmological parameters. With a simulated data set of 101 GRBs with a central value of the correlation slope that differs on the intrinsic one by a $5\\sigma$ factor, we find an overstimated value of the matter density parameter, $\\Omega_M$, compared to the value obtained with SNe Ia, while the Hubble constant, $H_0$, best fit value is still compatible in 1$\\sigma$ compared to other probes. We show that this compatibility of $H_0$ is due to the large intrinsic scatter associated with the simulated sample. Instead, if we consider a subsample of high luminous GRBs ($HighL$), we find that both the evaluation of $H_0$ and $\\Omega_M$ are not more compatible in 1$\\sigma$ and $\\Omega_M$ is underestimated by the $13\\%$. Ho...

Dainotti, Maria Giovanna; Piedipalumbo, Ester; Capozziello, Salvatore

2013-01-01

154

Green-Ampt infiltration model for sloping surfaces  

Science.gov (United States)

This work quantifies and explains the direct physical effects of slope angle on infiltration and runoff generation by extending the Green-Ampt equation onto sloping surfaces. A new extended solution using identical precipitation hydrographs was compared to the original formulation and then used to calculate the infiltration and runoff generation for different slope angles but for identical horizontal projection lengths. Homogeneous and isotropic soil is assumed, and two different boundary conditions for vertical rainfall are studied: ponded infiltration and infiltration under steady rainfall. Infiltration under unsteady rainfall was found to be similar to cases with steady rainfall. Both theoretical and numerical results show that infiltration increases with increasing slope angle. For cases with ponded infiltration the slope effect was generally not significant for mild to moderate slopes, but the slope effect became more important for low-intensity and short-duration rainfall events, especially as it delayed the time for ponding. It was also found that the cumulative vertical infiltration depth (Ihp) at ponding (or the initial loss) increases with increasing slope angle. The model was compared to Richards' equation on horizontal and sloping surfaces and found to perform well. The model's applicability for nonuniform slopes was discussed, and it was found that the model is generally applicable for isotropic and mildly anisotropic soils except for some small-scale topographic elements. Finally, the occurrence of nonvertical rainfall could increase runoff with increasing slope angle when rainfall deflects a large angle to upslope.

Chen, Li; Young, Michael H.

2006-07-01

155

Centrifuge Modeling of Slope Failure Induced by Rainfall  

Science.gov (United States)

Centrifuge modeling technique is used to study slope failure under normal and rainfall conditions. The slope models were prepared from sand mixed with 15% fines by weight, compacted at optimum water content of 7.7%. The modeling technique was first validated using slope models of different heights, inclinations and soil types. The Bishop's circular mechanism, together with the extended Mohr-Coulomb failure criterion, was able to simulate the slope failure reasonably well. The extended Mohr-Coulomb failure criterion expressed the strength of unsaturated compacted soil in terms of angle of internal friction and apparent cohesion. The rainfall of different intensities was then induced on the 60-degree stable slopes of sand with 15% fines. It was found that the failure of slope under rainfall may be interpreted as a reduction in apparent cohesion. The centrifuge tests also allowed the rainfall intensity-duration curve to be generated for the test slopes.

Ling, H.; Ling, H.; Li, L.

2009-04-01

156

Methodologies for risk analysis in slope instability  

International Nuclear Information System (INIS)

This paper is an approach to the different methodologies used in conducting landslide risk maps so that the reader can get a basic knowledge about how to proceed in its development. The landslide hazard maps are increasingly demanded by governments. This is because due to climate change, deforestation and the pressure exerted by the growth of urban centers, damage caused by natural phenomena is increasing each year, making this area of work a field of study with increasing importance. To explain the process of mapping a journey through each of the phases of which it is composed is made: from the study of the types of slope movements and the necessary management of geographic information systems (GIS) inventories and landslide susceptibility analysis, threat, vulnerability and risk. (Author)

157

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

158

A Linearized Solution of the Slope Crest Infiltration Problem  

Science.gov (United States)

It was found recently that the long-slope ponded infiltration solution applies also to a wide range of nonplanar topographies. The long-slope solution neglects any slope crest effect, and a careful analysis of this is needed. The present work reassesses the previous primitive estimate of the crest effect. We solve the problem of linearized infiltration into a symmetrical ridge with 45° slope angles. The integral matching of flow behavior gives results of ample accuracy for our purpose. The 45° slope is very steep in nature, but yields a simple product solution. We use this to calibrate the previous long-slope criterion for arbitrary slope angle. The primary slope crest effect is increase of moisture content and decrease of capillary potential gradients near the crest. The affected region propagates downslope but its influence on infiltration dynamics tends to dissipate because the relative importance of capillarity diminishes as time increases. We find that the previous criterion for applicability of long-slope infiltration dynamics was too conservative by a factor ranging from 2 at very small infiltration times to 100 at large times. The solution gives details of both downslope and inslope unsaturated flows. The ponded infiltration rate is least at the crest and increases downslope: This result is independent of linearization or slope angle.

Philip, J. R.

1992-04-01

159

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

160

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

161

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

Science.gov (United States)

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

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

2013-12-01

162

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

Directory of Open Access Journals (Sweden)

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

R. K. Umrao

2011-10-01

163

Slope analysis for elastic nucleon-nucleon scattering  

OpenAIRE

The diffraction slope parameter is investigated for elastic proton-proton and proton-antiproton scattering based on the all available experimental data at low and intermediate momentum transfer values. Energy dependence of the elastic diffraction slopes is approximated by various analytic functions. The expanded "standard" logarithmic approximations with minimum number of free parameters allow to describe experimental slopes in all available energy range reasonably. The esti...

Okorokov, V. A.

2009-01-01

164

Coherent sea-level fluctuations along the global continental slope  

OpenAIRE

Signals in sea-level or, more properly, sub-surface pressure (SSP; sea-level corrected for the inverse barometer effect) are expected to propagate rapidly along the continental slope due to the effect of sloping topography on wave modes, resulting in strongly correlated SSP over long-distances. Observations of such correlations around the Arctic and Antarctic are briefly reviewed, and then extended using satellite altimetry to the rest of the global continental slope. It is shown that such lo...

Hughes, Chris W.; Meredith, Michael P.

2006-01-01

165

High-Order FEM Formulation for 3-D Slope Instability  

OpenAIRE

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 deg...

Yatabe Ryuichi; Bhandary Netra Prakash; Tiwari Ram Chandra

2013-01-01

166

Seismic Stability Analysis of a Himalayan Rock Slope  

Science.gov (United States)

The seismic slope stability analysis of the right abutment of a railway bridge proposed at about 350 m above the ground level, crossing a river and connecting two huge hillocks in the Himalayas, India, is presented in this paper. The rock slopes are composed of highly jointed rock mass and the joint spacing and orientation are varying at different locations. Seismic slope stability analysis of the slope under consideration is carried out using both pseudo-static approach and time response approach as the site is located in seismic zone V as per the earth quake zonation maps of India. Stability of the slope is studied numerically using program FLAC. The results obtained from the pseudo-static analysis are presented in the form of Factor of Safety (FOS) and the results obtained from the time response analysis of the slope are presented in terms of horizontal and vertical displacements along the slope. The results obtained from both the analyses confirmed the global stability of the slope as the FOS in case of pseudo-static analysis is above 1.0 and the displacements observed in case of time response analysis are within the permissible limits. This paper also presents the results obtained from the parametric analysis performed in the case of time response analysis in order to understand the effect of individual parameters on the overall stability of the slope.

Latha, Gali Madhavi; Garaga, Arunakumari

2010-11-01

167

Analysis of Rainfall Infiltration Law in Unsaturated Soil Slope  

Science.gov (United States)

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

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

2014-01-01

168

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

OpenAIRE

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

Umrao, R. K.; Singh, R.; Ahmad, M.; Singh, T. N.

2011-01-01

169

The Slope Heuristics in Heteroscedastic Regression  

CERN Document Server

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

Saumard, Adrien

2011-01-01

170

Writing a Slope-Intercept Equation from a Graph  

Science.gov (United States)

This step by step lesson from Math Ops demonstrates how to write a slope-intercept equation from a graph. Students can read the text on the slides or follow along as it is read aloud. The slope-intercept format of a line is explained as well as how to write an equation for a line. Three examples are given.

2011-01-01

171

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

172

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

173

Preliminary blasting as a means of constructing the final slopes  

Energy Technology Data Exchange (ETDEWEB)

In order to undertake construction of a new belt at the Meirama opencast lignite workings in the Province of Coruna it has been necessary partially to re-site the slope of the general haulage drift. Preliminary blasting was thought to be the most suitable method of blasting in order to maintain slope stability of the rock mass. (17 refs.)

Lopez Jimeno, E.; Lopez Jimeno, C. (Lignitos de Meirama, La Coruna (Spain))

1983-01-01

174

Handling Correlations between Covariates and Random Slopes in Multilevel Models  

Science.gov (United States)

This article discusses estimation of multilevel/hierarchical linear models that include cluster-level random intercepts and random slopes. Viewing the models as structural, the random intercepts and slopes represent the effects of omitted cluster-level covariates that may be correlated with included covariates. The resulting correlations between…

Bates, Michael David; Castellano, Katherine E.; Rabe-Hesketh, Sophia; Skrondal, Anders

2014-01-01

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

US North Slope gas and Asian LNG markets  

Science.gov (United States)

Prospects for export of liquified natural gas (LNG) from Alaska's North Slope are assessed. Projected market conditions to 2010 show that new LNG capacity beyond announced expansions will be needed to meet regional demand and that supplies will probably come from outside the region. The estimated delivered costs of likely suppliers show that Alaska North Slope gas will not be competitive. The alternative North Slope gas development strategies of transport and sale to the lower 48 states and use on the North Slope for either enhanced oil recovery or conversion to liquids are examined. The alternative options require delaying development until US gas prices increase, exhaustion of certain North Slope oil fields, or advances occur in gas to liquid fuels conversion technology. ?? 1995.

Attanasi, E.D.

1994-01-01

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

Public transit bus ramp slopes measured in situ.  

Science.gov (United States)

Abstract Purpose: The slopes of fixed-route bus ramps deployed for wheeled mobility device (WhMD) users during boarding and alighting were assessed. Measured slopes were compared to the proposed Americans with Disabilities Act (ADA) maximum allowable ramp slope. Methods: A ramp-embedded inclinometer measured ramp slope during WhMD user boarding and alighting on a fixed-route transit bus. The extent of bus kneeling was determined for each ramp deployment. In-vehicle video surveillance cameras captured ramp deployment level (street versus sidewalk) and WhMD type. Results: Ramp slopes ranged from -4° to 15.5° with means of 4.3° during boarding (n?=?406) and 4.2° during alighting (n?=?405). Ramp slope was significantly greater when deployed to street level. During boarding, the proposed ADA maximum allowable ramp slope (9.5°) was exceeded in 66.7% of instances when the ramp was deployed to street level, and in 1.9% of instances when the ramp was deployed to sidewalk level. During alighting, the proposed ADA maximum allowable slope was exceeded in 56.8% of instances when the ramp was deployed to street level and in 1.4% of instances when the ramp was deployed to sidewalk level. Conclusions: Deployment level, built environment and extent of bus kneeling can affect slope of ramps ascended/descended by WhMD users when accessing transit buses. Implications for Rehabilitation Since public transportation services are critical for integration of wheeled mobility device (WhMD) users into the community and society, it is important that they, as well as their therapists, are aware of conditions that may be encountered when accessing transit buses. Knowledge of real world ramp slope conditions that may be encountered when accessing transit buses will allow therapists to better access capabilities of WhMD users in a controlled clinical setting. Real world ramp slope conditions can be recreated in a clinical setting to allow WhMD users to develop and practice necessary skills to safely navigate this environment. Knowing that extent of bus kneeling and ramp deployment level can influence ramp slope, therapists can educate WhMD users to request bus operators further kneel the bus floor and/or redeploy the ramp to a sidewalk level when appropriate, so that the least practicable slope will be presented for ingress/egress. PMID:24785405

Bertocci, Gina; Frost, Karen; Smalley, Craig

2014-05-01

179

Soil erosion processes on sloping land using REE tracer  

International Nuclear Information System (INIS)

Sheet erosion is the main performance in the slope soil erosion process at the primary stage of natural rainfall. For three times of rainfall during experiment, the ratios of sheet erosion to total erosion account for 71%, 48% and 49% respectively, which showed that the sloping erosion was still at the primary stage from sheet erosion to rill erosion. With the rainfall going, the rill erosion amount increase. It showed that soil erosion was changing from sheet erosion to rill erosion. The sources of sediment from different sections of the plot were analyzed, and the results indicated that whatever the sheet erosion changed, the ratio erosion of upper part of surface soil was always lower than 10%. Sheet erosion came mainly from the lower section of surface soil. With the ratios to the amount of total rill erosion changes, the rill erosion amount of each section regularly changes too. The general conclusion is that when the rainfall ends, relative erosion of different slope element to the foot of slope is: 1 meter away accounts for 16%, 2-4 meters away is 6% and 5-9 meters away is 3%. The ratio of rill erosion amount of these three slope element is 5:2:1, which shows the rill erosion amount are mainly from the slope element of 4 meters from the foot of slope. (authors)

180

Northern Hemisphere Slopes from Mars Orbiter Laser Altimeter  

Science.gov (United States)

Slopes, slope distributions, and macroscale surface roughness in the northern hemisphere of Mars have been measured from topographic profiles collected by the Mars Orbiter Laser Altimeter (MOLA) in the capture orbit, aerobraking hiatus and Science Phasing Orbit phases of the Mars Global Surveyor mission. The distribution function of slopes indicates that portions of the Martian surface fall into statistically distinct categories, distinguished by the histograms of both point-to-point slopes and of longer wavelength (10 and 100 km) slopes. Roughness correlates with elevation such that low regions tend to exhibit low roughness. Areas such as southern hemisphere highlands, dichotomy boundary terrains, and northern hemisphere lowlands all posses unique slope distribution signatures. The slope distribution within the Amazonis Planitia region, particularly member 3 of the Arcadia formation, displays an unusually smooth character. This region of anomalously low thermal inertia and low radar backscatter cross-section exhibits an rms variation in topography of Earth, i.e. oceanic abyssal plains and basins characterized by fluvial deposition. The smoothest measured volcanic surfaces as measured by altimetry on the Moon, Venus, and Mars are all significantly rougher than Amazonis. Saharan sand sheets are rougher by a factor of about three. Other regions in the Martian northern hemisphere that exhibit clear evidence of aeolian deposition are rougher than Amazonis as well.

Aharonson, O.; Zuber, M. T.

1998-12-01

181

Wave transformation and swash oscillation on gentle and steep slopes  

Science.gov (United States)

The numerical model developed previously for coastal structures is slightly modified and applied to predict the wave transformation in the surf and swash zones on gentle slopes as well as the wave reflection and swash oscillation on relatively steep beaches. The numerical model is one-dimensional in the cross-shore direction and is based on the finite amplitude, shallow water equations, including the effect of bottom friction, which are solved in the time domain for the incident wave train specified as input at the seaward boundary of the computation located outside the breakpoint. The slight modification is related to the effect of the time-averaged current on the seaward boundary condition and improves the agreement between the computed and measured mean water levels on gentle slopes. The modified numerical model is compared with available small-scale test data for monochromatic waves spilling on gentle slopes as well as for monochromatic waves plunging and surging on a relatively steep slope. Additional comparisons are made with small-scale tests conducted using transient monochromatic and grouped waves on a 1:8 smooth slope with and without an idealized nearshore bar at the toe of the 1:8 slope. As a whole, the numerical model is shown to be capable of predicting both time-varying and time-averaged hydrodynamic quantities in the surf and swash zones on gentle as well as steep slopes.

Kobayashi, Nobuhisa; Desilva, Gunamuni S.; Watson, Keith D.

1989-01-01

182

Geotechnical characteristics and slope stability in the Gulf of Cadiz  

Science.gov (United States)

Sedimentological and geotechnical analyses of thirty-seven core samples from the Gulf of Cadiz continental margin were used to define the regional variability of sediment properties and to assess slope stability. Considering the sediment property data set as a whole, there is an association between grain size, plasticity and water content. Any one of these properties can be mapped regionally to provide an indication of the dominant surface sediment lithology. Based on static sediment strength, a simplified slope stability analysis showed that only steep slopes (> 16??for even the most vulnerable sediment) can fail under static loading conditions. Accordingly, transient loads, such as earthquakes or storms, are needed to cause failure on more moderate slopes. A regional seismic slope stability analysis of the Cadiz margin was performed based on detailed geotechnical testing of four gravity core samples. The results showed that the stability of these slopes under seismic loading conditions depends upon sediment density, the cyclic loading shear strength, the slope steepness, and the regional seismicity. Sediment density and cyclic loading shear strength are dependent upon water content, which can act as a proxy for plasticity and texture effects. Specifically, Sediment in the water content range of 50-56% is most vulnerable to failure under cyclic loading within the Cadiz margin. As a result, for a uniform seismicity over the region, susceptibility to failure during seismic loading conditions increases with increasing slope steepness and is higher if the sediment water content is in the 50-56% range than if it is not. The only sampled zone of failure on the continental slope contains sediment with water content in this critical range. Storm-wave-induced instability was evaluated for the continental shelf. The evaluation showed that a storm having hundreds of waves with a height in the range of 16 m might be capable of causing failure on the shelf. However, no sediment failures were observed on the shelf that might have been caused by this mechanism.

Lee, H.; Baraza, J.

1999-01-01

183

Are North Slope surface alluvial fans pre-Holocene relicts?  

Science.gov (United States)

The surface morphology of the northern slope of the Brooks Range (North Slope) from the Canning River, Alaska, eastward is dominated by a series of large alluvial fans and braided streams floored by coarse alluvium. On the basis of our studies, we conclude that the fans are not prograding now nor have they been prograding at any time during the Holocene. During the latest transgression and the following sea-level highstand, the North Slope depositional environment and climate probably differed greatly from the present ones.

Reimnitz, Erk; Wolf, Stephen C.

1998-01-01

184

Photogrammetry and altimetry: Part C: frequency distributions of lunar slopes  

Science.gov (United States)

The metric and panoramic cameras aboard the Apollo 16 spacecraft provided photographs on which photogrammetric techniques may be used to obtain precise measurements of horizontal distances and elevations. These measurements of horizontal distances and elevations. These measurements may in turn be used to obtain slope-frequency distributions of lunar surfaces at various slope lengths and for various types of terrain and geologic map units (ref. 30-4). Bistatic radar and photoclinometric methods have also been used to obtain slope-frequency distributions of lunar surfaces. The problem arises as to how well these varied methods correlate with one another (ref. 30-5).

Wu, Sherman S.C.; Moore, H.J.

1972-01-01

185

Flow and seasonality in the Hebridean slope current  

OpenAIRE

The intensity, structure and variability of the slope current have been determined from 16 months of observations with Acoustic Doppler Current Profilers (ADCP) and conventional current meters on a cross-slope section at the Hebridean shelf edge during the Shelf Edge Study (SES) programme. After removal of the tidal signals, the mean flow over the upper slope is found to be closely parallel to the topography with speeds of ? 20 cm·s–1. The flow extends down to a depth of 500 m and is pre...

Souza, Alejandro J.; Simpson, John H.; Harikrishnan, M.; Malarkey, Jonathan

2001-01-01

186

Influence of Rainfall Patterns on the Instability of Slopes  

Directory of Open Access Journals (Sweden)

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

Muntohar A.S.

2013-01-01

187

30 CFR 716.2 - Steep-slope mining.  

Science.gov (United States)

...approximate original contour restoration requirements. (1) This...approximate original contour restoration requirements on steep slopes...variance from the requirement for restoration of the affected lands to...that adversely affects the ecology of any surface water or...

2010-07-01

188

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

189

Newton slopes for Artin-Schreier-Witt towers  

DEFF Research Database (Denmark)

We fix a monic polynomial f(x) in Fq[x] over a finite field and consider the Artin-Schreier-Witt tower defined by f (x); this is a tower of curves · · · ? Cm ? Cm?1 ? ···?C0 =A1, with total Galois group Zp. We study the Newton slopes of zeta functions of this tower of curves. This reduces to the study of the Newton slopes of L-functions associated to characters of the Galois group of this tower. We prove that, when the conductor of the character is large enough, the Newton slopes of the L-function form arithmetic progressions which are independent of the conductor of the character. As a corollary, we obtain a result on the behavior of the slopes of the eigencurve associated to the Artin-Schreier-Witt tower, analogous to the result of Buzzard and Kilford.

Davis, Christopher James; Wan, Daqing

2014-01-01

190

Open pit slope deformation monitoring by fiber Bragg grating sensors  

Science.gov (United States)

With microstrain resolution and the capability to sample at rates of 2000 Hz or higher, fiber Bragg grating (FBG) strain sensor offers exciting new possibilities for in situ deformation monitoring induced by blasting load in an open pit slope. Here, we are developing a new technology for measuring deformation in real time on the microstrain in an open pit slope during the blasting. A fiber optically instrumented rock mass strain sensor measured strain at 100-cm intervals along a two anchor rock bolt grouted in the slope intact rock mass. In field testing, a number of transient signals have been observed, which in some cases were large enough to trigger rapid sampling. The combination of short- and long-term observation offers new insight into the slope stability and blasting cumulative effects. Therefore, FBG sensors are a useful tool for measuring in situ strain in intact rock masses.

Xu, Guoquan; Xiong, Daiyu; Duan, Yun; Cao, Xiaoshuang

2015-01-01

191

30 CFR 785.15 - Steep slope mining.  

Science.gov (United States)

...DEPARTMENT OF THE INTERIOR SURFACE COAL MINING AND RECLAMATION OPERATIONS PERMITS AND COAL EXPLORATION SYSTEMS UNDER REGULATORY PROGRAMS REQUIREMENTS FOR PERMITS FOR SPECIAL CATEGORIES OF MINING § 785.15 Steep slope...

2010-07-01

192

APLLICATION OF DISTRIBUTED RAINFALL RUNOFF MODEL TO SLOPE FAILURE SIMULATION  

Science.gov (United States)

The objective of this research is to improve prediction performance of a distributed rainfall and sediment runoff model for better reservoir sedimentation management. This paper describes an advanced slope-failure simulation method base on basin geomorphology using distributed-parameter rainfall and sediment runoff model, which considers rain-factor and physically-based slope stability. The proposed method is applied to the three dam catchements: Yahagi Dam (504.5 km2), Miwa Dam (311.1km2), and Koshibu Dam (288.0km2), in Chubu, Japan. At each catchment, the model shows very good prediction results of slope failures, which is in good agreement with the locations of actual slope failures recognized by a detailed areal photo interpretation.

Nagatani, Gen; Mizuno, Naoya; Ishida, Hiroya; Ozawa, Kazuya; Takara, Kaoru

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

Review of Parallel Lines, Transversals, Slopes, And Equations of Lines  

Science.gov (United States)

This activity page will help you to review for the test coming up soon. Here is a section that will help you to remember all of the angles formed by a transversal and the properties involved: Practice with Parallel Lines and Angles Now, review how to find slopes and equations of lines: Practice with Slopes and Equations of Lines Now try some two column proofs: Two Column Proofs Practice Now you're ready to take the test! ...

Mrs. Neubert

2010-10-13

195

The Synthesis of Regression Slopes in Meta-Analysis  

OpenAIRE

Research on methods of meta-analysis (the synthesis of related study results) has dealt with many simple study indices, but less attention has been paid to the issue of summarizing regression slopes. In part this is because of the many complications that arise when real sets of regression models are accumulated. We outline the complexities involved in synthesizing slopes, describe existing methods of analysis and present a multivariate generalized least squares approach to t...

Becker, Betsy Jane; Wu, Meng-jia

2008-01-01

196

No Semiconjugacy to a Map of Constant Slope  

OpenAIRE

We study countably piecewise continuous, piecewise monotone interval maps. We establish a necessary and sufficient criterion for the existence of a nondecreasing semiconjugacy to a map of constant slope in terms of the existence of an eigenvector of an operator acting on a space of measures. Then we give sufficient conditions under which this criterion is not satisfied. Finally, we give examples of maps not semiconjugate to a map of constant slope via a nondecreasing map. Ou...

Misiurewicz, Micha?; Roth, Samuel

2014-01-01

197

The evolution of slope failures: mechanisms of rupture propagation  

OpenAIRE

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 undertake...

Petley, D. N.

2004-01-01

198

Kinetics of crimp and slope grip in rock climbing  

OpenAIRE

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

Schweizer, A.; Hudek, R.

2011-01-01

199

The effect of a single point on correlation and slope  

OpenAIRE

By augmenting a bivariate data set with one point, the correlation coefficient and/or the slope of the regression line can be changed to any prescribed values. For the target value of the correlation coefficient or the slope, the coordinates of the new point are found as a function of certain statistics of the original data. The location of this new point with respect to the original data is investigated.

Farnsworth, David L.

1990-01-01

200

Slope One Predictors for Online Rating-Based Collaborative Filtering  

OpenAIRE

Rating-based collaborative filtering is the process of predicting how a user would rate a given item from other user ratings. We propose three related slope one schemes with predictors of the form f(x) = x + b, which precompute the average difference between the ratings of one item and another for users who rated both. Slope one algorithms are easy to implement, efficient to query, reasonably accurate, and they support both online queries and dynamic updates, which makes the...

Lemire, Daniel; Maclachlan, Anna

2007-01-01

201

Families of trianguline representations and finite slope spaces  

CERN Document Server

We apply the theory of families of (phi,Gamma)-modules to trianguline families as defined by Chenevier. This yields a new definition of Kisin's finite slope subspace as well as higher dimensional analogues. Especially we show that these finite slope spaces contain eigenvarieties for unitary groups as closed subspaces. This implies that the representations arising from overconvergent p-adic automorphic forms on certain unitary groups are trianguline when restricted to the local Galois group.

Hellmann, Eugen

2012-01-01

202

Families of trianguline representations and finite slope spaces  

OpenAIRE

We apply the theory of families of (phi,Gamma)-modules to trianguline families as defined by Chenevier. This yields a new definition of Kisin's finite slope subspace as well as higher dimensional analogues. Especially we show that these finite slope spaces contain eigenvarieties for unitary groups as closed subspaces. This implies that the representations arising from overconvergent p-adic automorphic forms on certain unitary groups are trianguline when restricted to the loc...

Hellmann, Eugen

2012-01-01

203

Factorization and zero-slope limit of strings  

International Nuclear Information System (INIS)

Factorization properties of open strings are studied and the zero-slope limit of tachyon emission is discussed from this point of view. The generating functional for the S-matrix element is constructed and is shown to obey, in the zero-slope limit, the same functional equation as the one of phi3 field theory. Comments on the relation to recent approaches are made

204

Slope-mass-correlation in diffractive dissociation reactions  

International Nuclear Information System (INIS)

A set of new results of new Three Component Deck Model for Diffractive Dissociation Reactions is presented. These new results are confronted with recently published ones to obtain a general view of the model, its predictions and comparison with experimental results. Two kinds of correlations and amplitudes are given: the slope-mass-cos theta sup(GJ) and slope-mass-partial wave correlations. (Author)

205

Exploring Benthic Biodiversity Patterns and Hotspots on European Margin Slopes  

OpenAIRE

There is increasing evidence that continental slope ecosystems represent one of the major repositories of benthic marine biodiversity. The enhanced levels of biodiversity along slopes are hypothesized to be a source of biodiversity for continental shelves and deeper basins. Continental margins are increasingly altered by human activities, but the consequences of these anthropogenic impacts on benthic biodiversity and ecosystem functioning are almost completely unknown. Thus, there is an urgen...

Roberto Danovaro; Miquel Canals; Serge Heussner; Nikolaos Lampadariou; Ann Vanreusel

2009-01-01

206

Recurring Slope Lineae in Mid-Latitude and Equatorial Mars  

Science.gov (United States)

A key to potential present-day habitability of Mars is the presence of liquid H2O (water). Recurring slope lineae (RSL) could be evidence for the seasonal flow of water on relatively warm slopes. RSL are narrow (250 K to >300 K. In the past year we have monitored active RSL in equatorial (0°-15°S) regions of Mars, especially in the deep canyons of Valles Marineris. They are especially active on north-facing slopes in northern summer and spring and on south-facing slopes in southern spring and summer, following the most normal solar incidence angles on these steep slopes. However, predicted peak temperatures for north-facing slopes are nearly constant throughout the Martian year because orbital periapse occurs near the southern summer solstice. Although warm temperatures and steep low-albedo slopes are required, some additional effect besides temperature may serve to trigger and stop RSL activity. Seasonal variation in the atmospheric column abundance of water does not match the RSL activity. Although seasonal melting of shallow ice could explain the mid-latitude RSL, the equatorial activity requires a different explanation, perhaps migration of briny groundwater. To explain RSL flow lengths, exceeding 1 km in Valles Marineris, the water is likely to be salty. Several RSL attributes are not yet understood: (1) the relation between apparent RSL activity and dustiness of the atmosphere; (2) salt composition and concentration; (3) variability in RSL activity from year to year; (4) seasonal activity on north-facing equatorial slopes in spite of little change in temperature; and (5) temporal changes in the color properties of fans where RSL terminate. Continued orbital monitoring, laboratory experiments, and future orbital and landed exploration with new measurement types are needed. Equatorial water activity, if confirmed, creates new exploration opportunities and challenges. RSL >1 km long near boundary between Eos and Capri Chasmata of Valles Marineris, Mars.

McEwen, A. S.; Dundas, C. M.; Mattson, S.; Toigo, A. D.; Ojha, L.; Wray, J. J.; Chojnacki, M.; Byrne, S.; Murchie, S. L.; Thomas, N.

2013-12-01

207

The Spectral Slope and Kolmogorov Constant of MHD turbulence  

CERN Document Server

The spectral slope of strong MHD turbulence has recently been a matter of controversy. While Goldreich-Sridhar model (1995) predicts Kolmogorov's -5/3 slope of turbulence, shallower slopes were often reported by numerical studies. We argue that earlier numerics was affected by driving due to a diffuse locality of energy transfer in MHD case. Our highest-resolution simulation (3072^2x1024) has been able to reach the asymptotic -5/3 regime of the energy slope. Additionally, we found that so-called dynamic alignment, proposed in the model with -3/2 slope, saturates and therefore can not affect asymptotic slope. The observation of the asymptotic regime allowed us to measure Kolmogorov constant C_KA=3.2+-0.2 for purely Alfv\\'enic turbulence and C_K=4.1+-0.3 for full MHD turbulence. These values are much higher than the hydrodynamic value of 1.64. The larger value of Kolmogorov constant is an indication of a fairly inefficient energy transfer and, as we show in this Letter, is in theoretical agreement with our obse...

Beresnyak, Andrey

2010-01-01

208

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

209

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

210

Relating weak layer and slab properties to snow slope stability  

Science.gov (United States)

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 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.

Schweizer, J.; Reuter, B.

2014-07-01

211

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

212

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

213

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

OpenAIRE

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

214

Debris flows in a young mid-latitude crater on Mars: Evidence for recent water-bearing mass wasting and efficient insolation-controlled slope modification within the last  

Science.gov (United States)

Debris flows are moving masses of loose debris of varying grain sizes, water and air that travels down a slope under the influence of gravity. Terrestrial debris flows are mainly studied and monitored because of their hazardous nature. On Mars they may serve as important geomorphologic indicators of transient liquid water. The discovery of well-developed debris flow deposits within a very young southern mid-latitude crater (~0.2 Ma) highlights the impact of periglacial slope processes during recent climate conditions on Mars. We compared the morphology of debris flows on Svalbard as possible analogues to the observed deposits on Mars in order to infer possible formation mechanisms. Within our study crater on Mars, high-resolution imagery obtained by the HiRISE instrument (High Resolution Imaging Science Experiment) revealed typical debris-flow attributes such as overlapping terminal lobes, debris tongues, debris-flow fans, scoured channels with medial deposits (debris plugs), and well-defined lateral deposits (levées). Collectively, these attributes are found on studied debris flows on Svalbard. Additionally, our study crater's interior walls display mass-wasting with strong aspect-dependence, ranging from debris-flow dominated pole-facing slopes, to east-and-west-facing single channel gullies, and north-facing talus cones (grain flow). Our findings suggest that the debris flows are neither related to impact induced heating and release of meltwater or melting of an ice-rich mantling deposit since the latter is absent in the study crater. Instead, we propose that the debris flows are formed by melting of very recent snow deposits after the termination of the last Martian ice-age. As such it may represent one of the most recent geomorphological indicators of transient liquid water in the Martian mid-latitudes. Our study crater further illustrates the importance of regolith differences and micro-climate variability (e.g., insolation) in debris flow initiation on Mars. The distinct north-south asymmetry demonstrates that insolation-controlled slope processes are surprisingly efficient on Mars during the last <1 Ma.

Johnsson, Andreas; Reiss, Dennis; Hauber, Ernst; Hiesinger, Harald; Zanetti, Michael

2013-04-01

215

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.

216

Kinematics of running at different slopes and speeds.  

Science.gov (United States)

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

217

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

Directory of Open Access Journals (Sweden)

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

Jide Muili Akande

2011-06-01

218

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

219

Landform Degradation and Slope Processes on Io: The Galileo View  

Science.gov (United States)

The Galileo mission has revealed remarkable evidence of mass movement and landform degradation on Io. We recognize four major slope types observed on a number of intermediate resolution (250 m/pixel) images and several additional textures on very high resolution (10 m/pixel) images. Slopes and scarps on Io often show evidence of erosion, seen in the simplest form as alcove-carving slumps and slides at all scales. Many of the mass movement deposits on Io are probably mostly the consequence of block release and brittle slope failure. Sputtering plays no significant role. Sapping as envisioned by McCauley et al. remains viable. We speculate that alcove-lined canyons seen in one observation and lobed deposits seen along the bases of scarps in several locations may reflect the plastic deformation and 'glacial' flow of interstitial volatiles (e.g., SO2) heated by locally high geothermal energy to mobilize the volatile. The appearance of some slopes and near-slope surface textures seen in very high resolution images is consistent with erosion from sublimation-degradation. However, a suitable volatile (e.g., H2S) that can sublimate fast enough to alter Io's youthful surface has not been identified. Disaggregation from chemical decomposition of solid S2O and other polysulfur oxides may conceivably operate on Io. This mechanism could degrade landforms in a manner that resembles degradation from sublimation, and at a rate that can compete with resurfacing.

Moore, Jeffrey M.; Sullivan, Robert J.; Chuang, Frank C.; Head, James W., III; McEwen, Alfred S.; Milazzo, Moses P.; Nixon, Brian E.; Pappalardo, Robert T.; Schenk, Paul M.; Turtle, Elizabeth P.; DeVincenzi, Donald (Technical Monitor)

2001-01-01

220

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)

221

Kinetics of crimp and slope grip in rock climbing.  

Science.gov (United States)

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

Schweizer, Andreas; Hudek, Robert

2011-05-01

222

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

Science.gov (United States)

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

Boer, Theo A

2003-01-01

223

Development of a GIS-based failure investigation system for highway soil slopes  

Science.gov (United States)

A framework for preparation of an early warning system was developed for Maryland, using a GIS database and a collective overlay of maps that highlight highway slopes susceptible to soil slides or slope failures in advance through spatial and statistical analysis. Data for existing soil slope failures was collected from geotechnical reports and field visits. A total of 48 slope failures were recorded and analyzed. Six factors, including event precipitation, geological formation, land cover, slope history, slope angle, and elevation were considered to affect highway soil slope stability. The observed trends indicate that precipitation and poor surface or subsurface drainage conditions are principal factors causing slope failures. 96% of the failed slopes have an open drainage section. A majority of the failed slopes lie in regions with relatively high event precipitation (P>200 mm). 90% of the existing failures are surficial erosion type failures, and only 1 out of the 42 slope failures is deep rotational type failure. More than half of the analyzed slope failures have occurred in regions having low density land cover. 46% of failures are on slopes with slope angles between 20° and 30°. Influx of more data relating to failed slopes should give rise to more trends, and thus the developed slope management system will aid the state highway engineers in prudential budget allocation and prioritizing different remediation projects based on the literature reviewed on the principles, concepts, techniques, and methodology for slope instability evaluation (Leshchinsky et al., 2015).

Ramanathan, Raghav; Aydilek, Ahmet H.; Tanyu, Burak F.

2015-01-01

224

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

225

Slope measurement of bent plates using double grating shearing interferometry  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-06-20

226

Slope Stability Analysis Using Radial Slices: A Mathematical Model  

Science.gov (United States)

In this paper, a mathematical model has been formulated for calculating the factor of safety of a slope. Corresponding computer code has also been developed. Limit equilibrium method (moment equilibrium) has been adopted for calculating the net resulting driving and resisting forces. The probable slip circle region has been divided into radial slices for the simulation process. In this approach, the inter-slice shear forces are zero. Thus, the calculation process becomes simpler as compared to that with vertical slices. The slope stability analyses were done. Validation of the present program was done with existing limit equilibrium based methods. Various models were prepared and analysed with varying geometry and soil strength parameters. These models were also analysed with other limit equilibrium methods like Bishop, Janbu and Spencer method. The results were found to be in agreement with the results of other limit equilibrium methods for the same dump soil properties and slope parameters.

Kumar, Gyan Prakash; Das, Adarsha; Rai, Rajesh; Jaiswal, Ashok

2015-02-01

227

Violating the General Density-Slope Anisotropy Inequality  

CERN Document Server

We examine the robustness of the well-known empirical relationship between the density slope and the velocity anisotropy of collisionless systems. This relation, known as the Global Density-Slope Anisotropy Inequality (GDSAI) (Ciotti & Morganti, 2010), posits that no collisionless system with a globally positive distribution function exists where the anisotropy exceeds half of the power-law of the density slope. We significantly extend previous indications that the GDSAI is not a universal rule by identifying a class of models where violation occurs. These models possess a globally positive DF, have an isotropic central core, but are not guaranteed to be stable. Our analysis suggests that stability criteria provide a stronger basis for determining if a DF represents an equilibrium solution for a collisionless system.

Barber, Jeremy A

2014-01-01

228

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

229

Recurring Slope Lineae and Future Exploration of Mars  

Science.gov (United States)

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

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

2014-05-01

230

An Experimental Study of Submarine Canyon Evolution on Continental Slopes  

Science.gov (United States)

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

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

2013-12-01

231

Analytical approximation for the recession of a sloping aquifer  

Science.gov (United States)

An 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

232

Newton slopes for Artin-Schreier-Witt towers  

OpenAIRE

We fix a monic polynomial f(x) over a finite field and consider the Artin-Schreier-Witt tower defined by f(x); this is a tower of curves \\cdots \\to C_m \\to C_{m-1} \\to \\cdots \\to C_0 = A^1, with total Galois group Z_p. We study the Newton slopes of zeta functions of this tower of curves. This reduces to the study of the Newton slopes of L-functions associated to characters of the Galois group of this tower. We prove that, when the conductor of the character is large enough, ...

Davis, Christopher James; Wan, Daqing; Xiao, Liang

2013-01-01

233

Nepheloid layers and internal waves over continental shelves and slopes  

Science.gov (United States)

Theoretical and laboratory results indicate that bottom velocities within shoaling internal gravity waves intensify upslope approximately inversely proportional to the water depth. The elevated velocities (and bottom stresses) caused by shoaling and, possibly, breaking internal waves might explain the generation and maintenance of near-bottom nepheloid zones and attached turbid plumes that have been observed over certain continental shelves and slopes. This process is proposed as an explanation of zones of relatively low transmissibility that emanate from the upper continental slope near Newport submarine canyon off southern California. ?? 1986 Springer-Verlag New York Inc.

Cacchione, D.A.; Drake, D.E.

1986-01-01

234

Flows in a rotating cylinder with a sloping bottom  

International Nuclear Information System (INIS)

An analytic solution of non-axisymmetric flow in a rotating cylinder with a sloping bottom and a flat top, which is rotating slightly farster than the other walls, is obtained for compressible fluid, and is compared with the imcompressible counterpart considered by Pedlosky and Greenspan. In the incompressible fluid the flow field is z-independent due to Taylor-Proudman theorem, and the phenomenon so called westward intensification is observed. In the compressible case, on the other hand, horizontal flow lines are circular, while non-axisymmetric weak z-motion is induced by the bottom slope. (author)

235

Middle and upper jurassic depositional environments at outer shelf and slope of Baltimore Canyon Trough  

Energy Technology Data Exchange (ETDEWEB)

New CDP data acquired in the Baltimore Canyon Trough during project LASE made it possible to map a continuous Jurassic sedimentary sequence from the continental margin to the abyssal plain without interruption by basement structures. Intense carbonate sedimentation is inferred at the outer shelf during the Middle and Late Jurassic. Carbonate sedimentation probably started during the Middle Jurassic with a platform that prograded seaward with the development of ramps. By the Late Jurassic, a major reef complex had developed at the outer continental shelf. The onset of reef growth can be tentatively dated as 138 Ma by using the J1 reflector dated by the Deep Sea Drilling Project. A well-developed reef-talus deposit can be identified overlying the interface that generates the J1 reflector. A detailed analysis of semblancederived interval velocities in the reef-talus sequence indicates a compressional velocity of 4.3-4.5 km/sec (14,100-14,800 ft/sec) for that interval, which was part of a major barrier reef along the United States eastern margin. After the reef formed, the deep oceanic basin was mostly starved from shelf-derived sediments until the reef died and was buried by clastic sediments. By correlation of our seismic data and COST well information, that in the Baltimore Canyon Trough this reef had terminated by about the end of the Jurassic Period.

Gamboa, L.A.; Stoffa, P.L.; Truchan, M.

1985-04-01

236

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

237

Graphing a Slope-Intercept Equation Using Intercepts  

Science.gov (United States)

This step by step lesson from Math Ops teaches students "to use the x and y intercepts to graph a line for an equation in slope-intercept format." Three examples are given which illustrate how to graph these equations. Students may read the text on each slide or follow along and listen as it is read aloud.

2011-01-01

238

How the spatial variation of tree roots affects slope stability  

Science.gov (United States)

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

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

2010-05-01

239

Quantization for Regge slopes and psi-particles  

International Nuclear Information System (INIS)

It is shown that Regge slopes are quantized as ?'(n)=?'(1)/n2 (/n/=1.2,...) in the vortex model of the dual string, where n is the quantum number of the flux quantization. We propose a model that the newly discovered psi-particles have n=2 whereas ordinary hadrons have n=1. (auth.)

240

Slope versus Elasticity and the Burden of Taxation.  

Science.gov (United States)

Criticizes the standard presentation, in introductory economics, of the burden of a tax as an application of elasticity. Argues that using the slopes of a supply and demand curve is the simplest and easiest way to clarify tax incidence. Includes three graphs illustrating this approach. (MJP)

Graves, Philip E.; And Others

1996-01-01

241

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.

242

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

243

The Perceptual Experience of Slope by Foot and by Finger  

Science.gov (United States)

Historically, the bodily senses have often been regarded as impeccable sources of spatial information and as being the teacher of vision. Here, the authors report that the haptic perception of slope by means of the foot is greatly exaggerated. The exaggeration is present in verbal as well as proprioceptive judgments. It is shown that this…

Hajnal, Alen; Abdul-Malak, Daniel T.; Durgin, Frank H.

2011-01-01

244

On the processes of detachment in rock slope failure  

Science.gov (United States)

The failure of steep hard rock cliffs requires that a set of processes occur that allow detachment of one or more blocks from the rock mass. Whilst in general terms we understand the nature of these processes (reduction in strength of existing discontinuities through weathering; pore pressure generation; processes associated with temperature changes, sometimes in the presence of water; fracturing; etc), and the controls upon them, the specifics of their mechanisms remain rather elusive. The consequence is that models of the evolution of rock slopes, and the development of predictive tools for rock slope failure, remain rather basic and unsatisfactory for most environments. In this paper, the results of a range of studies on the behaviour of rock slopes and rock masses, both in the field and in the laboratory, are integrated to examine our state of the art in terms of understanding detachment. Use is made of understanding of time dependent and stress dependent rock failure mechanisms. Particular focus is paid to the relationship between fracture and rock slope collapse, and the role that external and internal processes play in driving failure. It is shown that during the development of final failure control on the rock mass processes increasingly transitions from external agents to internal dynamics. This provides a potential way in which to classify the evolution of failure and thus to predict the time of the final event, paving the way for improved warning systems.

Petley, D.

2009-04-01

245

The Snowmass Points and Slopes: Benchmarks for SUSY Studies  

International Nuclear Information System (INIS)

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

246

The Snowmass Points and Slopes: benchmarks for SUSY searches  

International Nuclear Information System (INIS)

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

247

Recent sedimentation on the new jersey slope and rise.  

Science.gov (United States)

Radiocarbon dating and sedimentological studies of closely spaced cores indicate movement during the Holocene of sediments on the New Jersey continental slope and upper rise between Wilmington and Lindenkohl canyons. The uneven time-stratigraphic thickness of the late Quaternary sediment sections between cores and the nonuniform deposition rate at any given core site and among core sites show that the sediment blanket in canyon and intercanyon areas has been affected by downslope, gravity-driven pocesses during the Holocene to the present. The reduced rate of deposition on the slope and upper rise between the late Pleistocene and the present is largely due to decreased off-shelf transport in response to the eustatic rise in sea level. Very old radiocarbon dates at core tops result from emplacement of older reworked materials from upslope or from truncation of sections by mass wasting processes exposing older material at the sea floor. These processes also account for an irregular sequence of dated sections within cores and stratigraphic irregularities of the surficial cover from core to core. Marked variability in deposition rates on the slope and upper rise is largely a function of topographic configuration, proximity and accessibility to sediment source, and transport processes seaward of the shelf break. Moreover, higher accumulation rates on the upper rise are attributed primarily to slope bypassing. Bypassing, prevalent during the late Pleistocene, has continued periodically to the present. PMID:17814323

Stanley, D J; Nelsen, T A; Stuckenrath, R

1984-10-12

248

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

249

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

250

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

251

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

252

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)

253

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

254

Landslides induced by heavy rainfall in July 2012 in Northern Kyushu District, Japan and the influence of long term rainfall increase comparing with the slope destabilization due to strong seismic shaking  

Science.gov (United States)

1. Objective We had a deluge in July 2012 in the northern Kyushu district with intense rainfall of 800mm and 108mm/hr. This intensity yielded countless traces of debris flow and landslides, slope failures that induced tremendous damage and causalities in the area. Hence, several field investigations and reconnaissance tasks were conducted to delve into this sediment-related disaster. The various results and the information obtained through this investigation were reported, mentioning the damage, the meteorological condition, geologic-geomorphologic features and hydraulic characteristics of the debris flows, vegetation effects, and the influence of the climate change. Increase in rainfall that may be induced by the global climate change is obvious in Kyushu district, Japan, according to the analysis of rain data observed in various locations including mountainside points that are not influenced by local warming due to urbanization. On this point of view, we are intrigued to elucidate the response of landslide to this increase in rainfall. Hence, its long term impact on this landslide disaster is also analyzed comparing with the slope destabilization due to strong seismic shaking. 2. Method and target areas Field investigation on landslides slopes, slope failures and torrents where debris flows occurred are conducted to obtain the geologic data, geo-structure, vegetation feature, soil samples and topographic data i.e. cross sections, then soil shear tests and soil permeability tests are also conducted. The rainfall data at the nearest rain observatory were obtained from the database of Japan meteorological agency. The long term impact on the slope stability at some slopes in the area is analyzed by the finite element method (FEM) combined with rain infiltration and seepage analysis with the long term rainfall fluctuation data, obtaining factor of safety ( Fs) on real landslide slopes. The results are compared with the destabilized influence on the slopes due to the soil strength reduction by seismic shaking. The target areas are located in northern Kyushu district, western Japan where they often have severe landslide disasters. The geology in research areas consists of Paleozoic and Mesozoic rocks (mainly schist, slate) and Quaternary volcanic sediment such as Aso volcano body. The vegetation consists of mainly Japanese cypress, cedar or bamboo. 3. Result and consideration Consequently, the long term rainfall increase in the region such as increment of approximately 20 mm/hr for rain intensity Ri in 36 years is confirmed statistically using Kendall's rank correlation, and it is found that its impact on slope stability is considerable and critical in other cases. In the sample landslide slopes, even the increase in rain of duration for only 10 years has impact to a certain extent on their stabilities in terms of Fs. The Fs calculated with rains in previous decade is higher than 1.0 that corresponds to stable state, whereas the Fs with present rains is lower than 1.0 such as 0.99 which means unstable state. Extremely heavy rainfall with this impact is generally cause extreme ground water pressure in the slope. It is also obvious that the extreme ground water content rendered even small landslides liquefied to be source of destructive debris flows. In this disaster, especially in the Aso volcanic region, tremendous number of debris flow occurred and even the talus cone slopes which are usually stable collapsed to flow down. However, the influence of the long term rainfall increase on the slopes (such as 1% decrease in Fs) is not relatively small compared with the destabilization of the slopes due to the reduction of soil strength by seismic shaking (8~9 % reduction in Fs after seismic shaking of even 490gal). 4. Conclusion In the disaster in July 2012, many landslides and debris flows originated from landslides induced by concentrated underground water supplied by the heavy rainfall occurred. The increase of rainfall due to climate change with the increasing rate such as 20 mm/hr surely has impact on almost landslide slopes i

Kubota, Tetsuya; Shinohara, Yoshinori; Aditian, Aril

2013-04-01

255

Area utilization efficiency of a sloping heliostat system for solar concentration.  

Science.gov (United States)

Area utilization efficiency (AUE) is formulated for a sloping heliostat system facing any direction. The effects of slope shading, incidence factor, sun shading, and tower blocking by the mirrors are all taken into account. Our results show that annually averaged AUEs calculated for heliostat systems (1) increase with tower height at low slope angles but less rapidly at high slopes, (2) increase monotonically with slope angle and saturate at large slopes for systems facing due south, (3) reach a maximum at a certain slope for systems facing other directions than due south, and (4) drop sharply at slopes greater than a certain value for systems facing due east or west due to slope shading effect. The results are useful for solar energy collection on nonflat terrains. PMID:18195827

Wei, L Y

1983-02-15

256

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

257

Analysis of rainfall-induced infinite slope failure during typhoon using a hydrological-geotechnical model  

Science.gov (United States)

Rainwater infiltration during typhoons tends to trigger slope instability. This paper presents the results of a study on slope response to rainwater infiltration during heavy rainfall in a mountain area of Taiwan. The Green-Ampt infiltration model is adopted here to study the behavior of rainwater infiltration on slopes. The failure mechanism of infinite slope is chosen to represent the rainfall-induced shallow slope failure. By combining rain infiltration model and infinite slope analysis, the proposed model can estimate the occurrence time of a slope failure. In general, if a slope failure is to happen on a slope covered with low permeability soil, failure tends to happen after the occurrence of the maximum rainfall intensity. In contrast, slope failure tends to occur prior to the occurrence of maximum rainfall intensity if a slope is covered with high-permeability soil. To predict the potential and timing of a landslide, a method is proposed here based on the normalized rainfall intensity (NRI) and normalized accumulated rainfall (NAR). If the actual NAR is higher than the NAR calculated by the proposed method, slope failure is very likely to happen. Otherwise, the slope is unlikely to fail. The applicability of the proposed model to occurrence time and the NAR-NRI relationship is evaluated using landslide cases obtained from the literature. The results of the proposed method are close to that of the selected cases. It verifies the applicability of the proposed method to slopes in different areas of the world.

Muntohar, Agus Setyo; Liao, Hung-Jiun

2009-01-01

258

[Treatment of flake fracture of the talus].  

Science.gov (United States)

This is a report on 18 osteochondral lesions of the talar dome after sprained ankles and ruptured lateral collateral ligaments of the ankle. They were classified according to Berndt & Harty. The treatment of choice in recent flake fractures is the reduction and glueing with fibrine. Very good results were obtained according to Weber. The recommended treatment of ancient flake fractures frequently occurring to elder patients is the removal of the fragment and the drilling of the subchondral bone. PMID:2472036

Ittner, G; Jaskulka, R; Fasol, P

1989-01-01

259

"Taevaredel" sündis Billite talus / Meeli Müüripeal  

Index Scriptorium Estoniae

Billite talust, kus läti kirjanik ja luuletaja Edvards Virza (1883-1940) kirjutas romaani "Taevaredel" ("Straumeni"). Tõlk, kirjanik ja diplomaat Anna Zhigure oma vanaisa E. Virza kirjutatud romaani tähendusest lätlastele ja Billite talust, kus praegu elab A. Zhigure vend. 4 värv. ill

Müüripeal, Meeli, 1963-

2006-01-01

260

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

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

Desirable plant root traits for protecting unstable slopes against landslides  

Science.gov (United States)

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

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

2009-04-01

263

Surface Slope Metrology on Deformable Soft X-ray Mirrors  

International Nuclear Information System (INIS)

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

264

Oscillating Nocturnal Slope Flow in a Coastal Valley  

DEFF Research Database (Denmark)

Observations of slope flows in a coastal valley are analyzed. The diurnal variation of upslope and downslope flows depends on season in a systematic way which appears to be related to the high latitude of the observational site and the presence of a nearby layer of marine air. Summer nocturnal flow over the sloping valley floor was studied during a special observing campaign. A downslope gravity flow interacts with even colder surface air at the valley floor. The latter originates as cold marine air or previous drainage of cold air. Regular oscillations which appear to be trapped, terrain-related internal gravity waves, exert a major influence on the downslope flow and its interaction with pre-existing cold air at the floor of the valley

Gryning, Sven-Erik; Larsen, SØren Ejling

1985-01-01

265

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

266

Alaska North Slope oil-field restoration research strategy. Manual  

International Nuclear Information System (INIS)

The 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 at least the following entities: The U.S. Army Corps of Engineers, EPA, National Marine Fisheries, US FWS, BLM, the Alaska Department of Natural Resources, and the North Slope Borough). The purpose of this strategy is to: (1) identify major information or knowledge gaps that have inhibited restoration activities or slowed the regulatory decision process, (2) determine the potential for filling knowledge gaps through research, and (3) suggest tentative priorities for research that are based on the needs identified in steps one and two

267

Slope stabilization at El Cerrejon coal mine, Colombia, South America  

Energy Technology Data Exchange (ETDEWEB)

The expanded west pit of the 15 Mta (13.6 stpy) El Cerrejon mine will eventually reach a maximum depth of 270 m (890 ft). Slope-stability evaluations indicated that this depth, combined with structural complexities, would create a serious risk of footwall instability. Stabilization calls for anchoring the footwall by the installation of 9- to 33-m- (30- to 108-ft) long multistrand steel cable bolts. For each of the 15-m- (50-ft-) high mining benches, a row of bolts is installed with variable horizontal spacing, depending on the dip magnitude. Cable bolting is now standard operating practice,and an estimated 11,800 bolts will be installed during the life of the mine. Results to date have been satisfactory in terms of the stability condition of the bolted slopes. 2 refs., 10 figs., 2 tabs.

Jaramillo, M. [International Colombia Resources (Intercor), Baranquilla (Colombia)

1996-12-01

268

Quantitative laboratory observations of internal wave reflection on ascending slopes  

CERN Document Server

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

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

2006-01-01

269

Stability of vegetated slopes in unsaturated conditions: a numerical study  

Science.gov (United States)

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

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

2014-05-01

270

Three dimensional slope stability problem with a surcharge load  

Science.gov (United States)

An analytical solution for the three dimensional stability analysis of the ultimate uniform patched load on top of a slope is developed by the limit analysis using kinematically admissible failure mechanisms. The failure mechanism which is assumed in the analytical solution is verified by three-dimensional strength reduction analyses and laboratory model test. Furthermore, the proposed method and the results are further compared with some published results for illustrating the applicability of the proposed failure mechanism.

Cheng, Y. M.; Li, N.; Yang, X. Q.

2015-02-01

271

Conservation laws for shallow water waves on a sloping beach  

OpenAIRE

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 na...

Yilmaz Akyildiz

1986-01-01

272

Relaxing Competition through Speculation: Committing to a Negative Supply Slope  

OpenAIRE

Abstract: We demonstrate how suppliers can take strategic speculative positions in derivatives markets to soften competition in the spot market. In our game, suppliers first choose a portfolio of call options and then compete with supply functions. In equilibrium firms sell forward contracts and buy call options to commit to downward sloping supply functions. Although this strategy is risky, it reduces the elasticity of the residual demand of competitors, who increase their mark-ups in respon...

Holmberg, Pa?r; Willems, Bert

2012-01-01

273

Semiconjugacy to a map of a constant slope  

OpenAIRE

It is well known that a continuous piecewise monotone interval map with positive topological entropy is semiconjugate to a map of a constant slope and the same entropy, and if it is additionally transitive then this semiconjugacy is actually a conjugacy. We generalize this result to piecewise continuous piecewise monotone interval maps, and as a consequence, get it also for piecewise monotone graph maps. We show that assigning to a continuous transitive piecewise monotone ma...

Alseda?, Llui?s; Misiurewicz, Micha?

2014-01-01

274

Intrusions of slope current water onto the NW European shelf  

Science.gov (United States)

We report on a 22-year time-series from a current meter mooring in the Tiree Passage, a SW-NE orientated strait between the Isle of Mull and the Isles of Coll and Tiree on the western coast of Scotland. The mooring is sited in at water depth of 50 m in the narrowest sector of the Passage. Hourly current and temperature measurements began in June 1981 at one depth, and at two depths from November 1987. Hourly salinity measurements began in September 1993 at both depths. The average volume flux through the Tiree Passage is calculated to be 0.067 Sv, comparable to the flux of Irish Sea/Clyde Sea water through the North Channel (0.077 Sv). The episodic contribution to the Tiree Passage water of Atlantic Slope Current water is the subject of this paper. This has relevance to both shelf edge exchange processes and coastal water quality issues. A strong seasonal temperature signal was observed in the passage (6C). No seasonality in salinity was observed, but variability increased in year-months 7-8, and 11-12. Eleven events have been identified over a period of 5 years (1993-1997) when salinities exceeded 34.5, thought to be the signature of Atlantic Slope water intrusion (S=35.3). During each of these episodes, all of 2-3 days duration, the water column was stratified, with ?? =0.2 to 0.3 kgm -3 . Bottom salinities were invariably higher, whilst temperature inversion occurred during winter intrusions; indicative of slope water intrusion. No significant correlation of these events was found with wind speed or direction, rainfall, barotropic pressure gradients (from sea level records), tidal parameters, or Irish Sea salinities. It is concluded that baroclinic processes in the Slope Current are responsible and investigation ontinues along this line of enquiry.

Griffiths, C. R.; Inall, M. E.; Ribeiro, C.

2003-04-01

275

Measures of Spectral Slope Using an Excised Larynx Model  

OpenAIRE

Spectral measures of the glottal source were investigated using an excised canine larynx model for various aerodynamic and phonatory conditions. These measures included spectral harmonic difference H1-H2 and spectral slope that are highly correlated with voice quality but not reported in a systematic manner using an excised larynx model. It was hypothesized that the acoustic spectra of the glottal source were significantly influenced by the subglottal pressure, glottal adduction, and vocal fo...

Alipour, Fariborz; Scherer, Ronald C.; Finnegan, Eileen

2011-01-01

276

Slope failures on the flanks of the western Canary Islands  

OpenAIRE

Landslides have been a key process in the evolution of the western Canary Islands. The younger and more volcanically active Canary Islands, El Hierro, La Palma and Tenerife, show the clearest evidence of recent landslide activity. The evidence includes landslide scars on the island flanks, debris deposits on the lower island slopes, and volcaniclastic turbidites on the floor of the adjacent ocean basins. At least 14 large landslides have occurred on the flanks of the El Hierro, La Palma and T...

Masson, Dg; Watts, Ab; Gee, Mjr; Urgeles, R.; Mitchell, Nc; Le Bas, Tp; Canals, M.

2002-01-01

277

Dynamic Slope Scaling Procedure to solve Stochastic Integer Programming Problem  

OpenAIRE

Stochastic programming deals with optimization under uncertainty. A stochastic programming problem with recourse is referred to as a two-stage stochastic problem. We consider the stochastic programming problem with simple integer recourse in which the value of the recourse variable is restricted to a multiple of a nonnegative integer. The algorithm of a dynamic slope scaling procedure to solve the problem is developed by using the property of the expected recourse function. The numerical expe...

Takayuki Shiina; Chunhui Xu

2012-01-01

278

Unitarity lower bounds on logarithmic slope of diffraction peak  

International Nuclear Information System (INIS)

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

279

Multipurpose fiber-optic sensor with sloped tip  

Science.gov (United States)

Fiber-optic sensors C FOS) are wi. del y used for rioncontact measurements due to their simplicity, small size, insensitivity to I nfl uence of el ectromagneti C fiel ds , hi gh metrol ogi cal characteristics, etc. The operation principle of FOS with intensity modul ati on techni que I s based on the photodetector regi strati on of 1ight , reflected from the control 1 ed surface E I ) . The i ntensi ty of detected 1 1 ght depends on th FOS' s di stance from the control 1 ed surface, its form and inclination to sensor's axis, FOS shift speed, etc. So they can be consider multipurpose. We are devel opi ng FOS wi th i ntensi ty modul ati on techni que wi th traight tips as well as with sloped tips. In FOS with sloped tips the light ring spot is appearing on the controlled surface due to the effect of symmetry. We use thi s phenomena to empl oy refl ected 1 i ght more efficiently and to increase the FOS characteristics. Tak i ng I nto account the fact that pr obl ems of cal cul aWl on of fibers with sloped tip were not analyzed in details earlier-, in particular, only the case of light distribution of parallel beams runni ng was consi dered E 2) we wi I 1 conduct a consi stent cal cul ati on of bounds of i rradi ance fi ci d , created by a fi ber wi th sl oped tip, esti mate I i ght di stri buti on I n a 1 1 ght spot , and determi. ne characteristics of the FOS with sloped tip.

Melnik, Ivan S.; Krivokhizha, A. M.; Ptashnik, O. V.

1991-08-01

280

Spreading of viscous fluids and granular materials on slopes  

OpenAIRE

Materials can flow down a slope in a wide range of geophysical and industrial contexts, including lava flows on volcanoes and thin films on coated surfaces. The aim of my research is to provide quantitative insight into these forms of motion and their dependence on effects of the topography, the volume and the rheology of the flowing structure. Numerous different problems are investigated through mathematical models, which are developed analytically and confirmed by laboratory experiments. ...

Takagi, Daisuke

2010-01-01

281

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

282

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

283

Pleistocene terraced fluvial succession, northern slope of the Torino Hill.  

OpenAIRE

A Pleistocenic terraced fluvial succession is found in the northern slope of the Torino Hill. This succession consists of many relics of flat surfaces, separated by scarps, with often associated sandy and silty deposits, suspended from 30 to 400 m on the Po Plain. Surfaces at high levels are more deformed, dissected and mostly deprived of their original sediments; lower ones are less deformed, more continuous and conservative. In the W sector of the area, surfaces form a degrading terrace...

Forno, Maria Gabriella

2007-01-01

284

Modeling the variability of the Antarctic Slope Current  

Science.gov (United States)

One of the main features of the oceanic circulation along Antarctica is the Antarctic Slope Current. This circumpolar current is westward and allows communication between the three major basins around Antarctica. The Antarctic Slope Current is not very well known due to difficult access and the presence of sea ice during several months, allowing in situ study only during summertime. Moreover, only few numerical studies of this current have been carried out. Here, we investigate the sensitivity of this current to two different atmospheric forcing sets and to four different resolutions in a coupled ocean-sea ice model (NEMO-LIM). Two series of simulation are conducted. For the first one, global configurations are run at coarse (2°) to eddy permitting resolutions (0.25°) and, for the second one, simulations with two atmospheric forcing sets with a regional configuration (south of 30°S) at 0.5° resolution are performed. The first atmospheric forcing set is based on ERA40 reanalysis and CORE data, while the second one is based on a downscaling of the reanalysis ERA40 by the MAR regional atmospheric model. The MAR model is tuned for the Antarctic region in term of orography. This improvement allows stronger katabatic and easterly winds and a colder atmosphere over the ocean. In the presentation, we will present a synthesis of the sensitivity experiments with a particular focus on seasonal and inter-annual variability of the Antarctic Slope Current between 0 and 2000 m along East Antarctica Coast and its response to atmospheric forcing and model resolution. Our results (i) question the ability of coarse-resolution models to accurately capture well the Antarctic Slope Current along East Antarctica and (ii) illustrate the impact of forcing fields on variability of this current.

Mathiot, Pierre; Goosse, Hugues; Fichefet, Thierry; Barnier, Bernard

2010-05-01

285

Estimation of the slope of the acoustic attenuation coefficient.  

Science.gov (United States)

In this paper, a theoretical framework is developed which removes the Gaussian assumption commonly used in ultrasonic attenuation estimation based on mean frequency shift. The theory is developed for general non-Gaussian spectra and for media whose attenuation coefficient is nonlinear with frequency. Then, a linear approximation in the estimation of the attenuation coefficient's slope is examined. It is shown that the error due to the linear approximation is negligibly small. PMID:6539975

Shaffer, S; Pettibone, D W; Havlice, J F; Nassi, M

1984-04-01

286

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

287

Meteorological, elevation, and slope effects on surface hoar formation  

Science.gov (United States)

Failure in layers of buried surface hoar crystals (frost) can cause hazardous snow slab avalanches. Surface hoar crystals form on the snow surface and are sensitive to micro-meteorological conditions. In this study, the role of meteorological and terrain factors were investigated for three surface hoar layers in the Columbia Mountains of Canada. The distribution of crystals was observed over different elevations and aspects during 20 days of field observations. The same layers were modelled on a 2.5 km horizontal grid by forcing the snow cover model SNOWPACK with forecast weather data from a numerical weather prediction model. The moisture content of the air (i.e. absolute humidity) had the largest impact on modelled surface hoar growth, with warm and moist air being favourable. Surface hoar was most developed at certain elevation bands, usually corresponding to elevations with warm humid air, light winds, and cold surface temperatures. SNOWPACK simulations on virtual slopes systematically predicted smaller surface hoar on south-facing slopes. In the field, a complex combination of surface hoar and sun crusts were observed, suggesting the model did not adequately resolve the surface energy balance on slopes. Overall, a coupled weather-snow cover model could benefit avalanche forecasters by predicting surface hoar layers on a regional scale over different elevation bands.

Horton, S.; Schirmer, M.; Jamieson, B.

2015-03-01

288

Coherent sea-level fluctuations along the global continental slope.  

Science.gov (United States)

Signals in sea-level or, more properly, sub-surface pressure (SSP; sea-level corrected for the inverse barometer effect) are expected to propagate rapidly along the continental slope due to the effect of sloping topography on wave modes, resulting in strongly correlated SSP over long-distances. Observations of such correlations around the Arctic and Antarctic are briefly reviewed, and then extended using satellite altimetry to the rest of the global continental slope. It is shown that such long-distance correlations are common, especially in extra-tropical regions. Simple correlations from altimetry cannot, however, establish the wave speed, or whether waves are responsible for the correlations as opposed to large-scale coherence in the forcing. A case study around South America is used to highlight some of the complications, and is found to strengthen the case for the importance of wave modes in such long-distance SSP coherence, although more detailed in situ data are required to resolve the cause of the correlations. PMID:16537146

Hughes, Chris W; Meredith, Michael P

2006-04-15

289

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

290

Case study : the Macallen Building Condominiums sloping green roof  

Energy Technology Data Exchange (ETDEWEB)

A nearly one-half acre sloping green roof on top of Boston's Macallen Building Condominiums was discussed. The design team of Pappas Enterprises developed this multi-family residential, environmentally sound building following the United States Green Building Council's LEED rating system. Strategies for natural light and air were used along with extensive application of recycled materials, efficiency in HVAC systems including energy recovery and access to public transportation. The central theme of this project in sustainable development was storm water retention through the use of a green roof installation. The parking garage contains stormwater retention tanks, two energy recovery units and all the major mechanical equipment for the project. The innovation in this project for the structural and envelope engineers was the support and retention of a planted roof with a significant slope. The details of the structure were further complicated by the inclusion of twelve balconies, sunken into the sloping roof, which provide private outdoor space for the penthouse units. Sedum were the recommended plantings for the Boston area, because of their appropriateness for hardiness zone 4 and heat zones 3 to 8. 7 figs.

Johnson, M.H.; Louis, M.J. [Simpson Gumpertz and Heger Inc., Boston, MA (United States)

2007-07-01

291

Slope seeking for autonomous lift improvement by plasma surface discharge  

Science.gov (United States)

The present paper describes an experimental investigation of closed-loop separation control using plasma actuators. The post-stall-separated flow over a NACA 0015 airfoil is controlled using a single dielectric barrier discharge actuator located at the leading edge. Open-loop measurements are first performed to highlight the effects of the voltage amplitude on the control authority for freestream velocities of 10-30 m/s (chord Re = 1.3 × 105 to 4 × 105). The results indicate that partial or full reattachment can be achieved and motivate the choice of the slope seeking approach as the control algorithm. A single-input/single-output algorithm is used to autonomously seek the optimal voltage required to achieve the control objective (full flow reattachment associated with maximum lift). The paper briefly introduces the concept of slope seeking, and a detailed parameterization of the controller is considered. Static (fixed speed) closed-loop experiments are then discussed, which demonstrate the capability of the algorithm. In each case, the flow can be reattached in an autonomous fashion. The last part of the paper demonstrates the robustness of the gradient-based, model-free scheme for dynamic freestream conditions. This paper highlights the capability of slope seeking to autonomously achieve high lift when used to drive the voltage of a plasma actuator. It also describes the advantages and drawbacks of such a closed-loop approach.

Benard, Nicolas; Moreau, Eric; Griffin, John; Cattafesta, Louis N., III

2010-05-01

292

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

293

Applications and developments of the interferometric strain/slope rosette  

Science.gov (United States)

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

Tjhung, Tana

294

Experimental research on a slope unstabilization process with a complex movement of groundwater  

Science.gov (United States)

In Japan, many slope disasters occur by typhoon, long-term rainfall and short-time heavy rainfall, where properties and lives have been annually lost. Slope failure is still the main one of the natural disasters. Slope failure mechanism is not understood well, for example, it unable to predict the timing of failure. Therefore, a method with extensometers were applied for prediction of slope collapse (Fukuzono, 1985). However, the accurate prediction is very difficult because the allowable time for warning is sometimes too short. The warning system must be improved for the specific each slope. New rational index to predict slope failure with early stage also must be studied through such experiments. Slope failure(shallow landslide) occurs on the weathered layer with a thickness of about 1 to 2m. In such conditions, ease of infiltration by heavy rainfall makes land collapsing quite often and repeatedly. Mechanism of slope failure is induced by 1) water pressure or table by rainfall, 2) reduction of strength like cohesion, 3)increase of self weight by water. This must be verified. So we conducted the large-scale model slope test with rainfall to understand the process of slope unstabilization by large-scale rainfall simulator at National research Institute for earth science and disaster prevention. We will express the part of the results to discuss the mechanism of slope failure. In one of the main results, complex movement of groundwater in the slope play the main roll of slope unstabilization.

Sakai, N.

2013-12-01

295

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

Directory of Open Access Journals (Sweden)

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

M. Ahmad

2013-01-01

296

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

297

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

298

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

299

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

300

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

Science.gov (United States)

...Bureau of Ocean Energy, Management, Regulations, and...the Bureau of Land Management's Alaska State Director...of the Interior's management. Duties could include...North Slope Science Initiative (NSSI) member organizations...North Slope Science Plan and provide...

2011-09-14

301

Halocline water modification and along slope advection at the Laptev Sea continental margin  

OpenAIRE

A general pattern in water mass distribution and potential shelf–basin exchange is revealed at the Laptev Sea continental slope based on hydrochemical and stable oxygen isotope data from the summers 2005–2009. Despite considerable interannual variations, a frontal system can be inferred between shelf, continental slope and central Eurasian Basin waters in the upper 100 m of the water column along the continental slope. Net sea-ice melt is consistently found at the continental slope. Howev...

Bauch, D.; Torres-valdes, S.; Polyakov, I.; Novikhin, A.; Dmitrenko, I.; Mckay, J.; Mix, A.

2013-01-01

302

Trophic ecology of deepwater fishes associated with the continental slope of the eastern Norwegian Sea  

OpenAIRE

In June 1995 and 1996 demersal fishes on the continental slope of the eastem Norwegian Sea were sampled to study distribution patterns and community structure. The diets of the more abundant slope species were characterised and linkages within the upper slope food-web identified. Few cases of predator-prey relationships between the typical slope fishes were found. Most of the smaller fishes fed on epibenthic crustaceans such as amphipods and mysids, while pelagic crustaceans and fish dominate...

Bergstad, Odd Aksel; Bjelland, Otte

1998-01-01

303

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

304

Dynamic Slope Scaling Procedure to solve Stochastic Integer Programming Problem  

Directory of Open Access Journals (Sweden)

Full Text Available Stochastic programming deals with optimization under uncertainty. A stochastic programming problem with recourse is referred to as a two-stage stochastic problem. We consider the stochastic programming problem with simple integer recourse in which the value of the recourse variable is restricted to a multiple of a nonnegative integer. The algorithm of a dynamic slope scaling procedure to solve the problem is developed by using the property of the expected recourse function. The numerical experiments show that the proposed algorithm is quite efficient. The stochastic programming model defined in this paper is quite useful for a variety of design and operational problems.

Takayuki Shiina

2012-12-01

305

A New Formula for Front Slope Recession of Berm Breakwaters  

DEFF Research Database (Denmark)

The front slope stability of breakwaters with a homogeneous berm was studied in a large number of two dimensional model tests at Aalborg University, Denmark. The results are presented together with a new formula for prediction of the berm recession which is the most important parameter for describing the reshaping. The formula has also been calibrated and validated against model test data from other researchers. The significance of the new design formula is that it predicts berm recession much better than the existing methods, especially in case of more stable structures.

Andersen, Thomas Lykke; Burcharth, Hans F.

2010-01-01

306

HDMR methods to assess reliability in slope stability analyses  

Science.gov (United States)

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

Kozubal, Janusz; Pula, Wojciech; Vessia, Giovanna

2014-05-01

307

Katabatic flows over steep alpine slopes covered with short vegetation  

Science.gov (United States)

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

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

2013-12-01

308

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

309

Variance-in-Mean Effects of the Long Forward-Rate Slope  

DEFF Research Database (Denmark)

This paper contains an empirical analysis of the dependence of the long forward-rate slope on the long-rate variance. The long forward-rate slope and the long rate are described by a bivariate GARCH-in-mean model. In accordance with theory, a negative long-rate variance-in-mean effect for the long forward-rate slope is documented. Thus, the greater the long-rate variance, the steeper the long forward-rate curve slopes downward (the long forward-rate slope is negative). The variance-in-mean effect is both statistically and economically significant.

Christiansen, Charlotte

2005-01-01

310

Altitude-Slope Relationships For Each Geology in Accretionary Complex Based on GIS Analysis  

Science.gov (United States)

Quantitative analysis with DEMs based on GIS (Geographic Information System) is a valid method to prove relationships among slope angle, altitude and bedrock geology. This paper discusses the relations among slope angle, geology, and altitude in two regions (Chubu and Kinki) in the Shimanto belt that is Cretaceous to Paleogene accretionary zone at the outer zone of Southwest Japan. Those relations are often compared in these areas for these clear reliefs. We particularly investigated the altitude-slope relationship for each geological unit (e.g. sandstone-dominant, mudstone-dominant, sandstone-mudstone alternation), because of the strong dependence of the slope angle on the altitude has already been indicated for the Southern Japanese Alps. In Chubu region, all of altitude-slope relationships for each geological unit show that the slope angle in lower altitude zones (= ca. 800 m) are relatively constant. Mean slope angles in higher altitude zones are different according to bedrock geology but most of them are between 28 and 35 degrees. In contrast, Paleogene mudstone-dominant Mikura Groups have lower slope angles in high altitude zones. This area correspond to the geology types with markedly low slope angles indicating that the susceptibility to slow gravitational landslides accounts for the variation in the slope angle. In Kinki region, all of altitude-slope relationships for each geological unit show that the slope angle in lower altitude zones (= ca. 500 m) are relatively constant. Mean slope angles in higher altitude zones are different according to bedrock geology but most of them are between 20 and 25 degrees. In contrast, Paleogene mudstone-dominant Otonashigawa Groups have lower slope angles in high altitude zones. This area, similarly in Chubu region, correspond to the geology types with markedly low slope angles indicating that the susceptibility to slow gravitational landslides accounts for the variation in the slope angle. As a result, most terrains in the study area have similar altitude-slope relationships irrespective of bedrock geology indicating that geology plays a relatively minor role in determining slope angles. Terrains underlain by some specific rocks, however, are highly susceptible to slow gravitational landslides and thus have markedly reduced slope angles than other terrains with similar altitudes. Among terrains underlain by rocks with equivalent ages, mudstone-dominant areas tend to have slightly lower slope angles than sandstone-dominant areas. This observation is also ascribable to the higher landslide susceptibility of mudstone.

Kawabata, D.; Okada, A.

2001-12-01

311

Testing the product of slopes in related regressions  

Science.gov (United States)

A study was conducted of the relationships among neuroprotective factors and cytokines in brain tissue of mice at different ages that were examined on the effect of dietary restriction on protection after experimentally induced brain stroke. It was of interest to assess whether the cross-product of the slopes of pairs of variables vs. age was positive or negative. To accomplish this, the product of the slopes was estimated and tested to determine if it is significantly different from zero. Since the measurements are taken on the same animals, the models used must account for the non-independence of the measurements within animals. A number of approaches are illustrated. First a multivariate multiple regression model is employed. Since we are interested in a nonlinear function of the parameters (the product) the delta method is used to obtain the standard error of the estimate of the product. Second, a linear mixed-effects model is fit that allows for the specification of an appropriate correlation structure among repeated measurements. The delta method is again used to obtain the standard error. Finally, a non-linear mixed-effects approach is taken to fit the linear-mixed-effects model and conduct the test. A simulation study investigates the properties of the procedure. PMID:25346580

Morrell, Christopher H.; Shetty, Veena; Phillips, Terry; Arumugam, Thiruma V.; Mattson, Mark P.; Wan, Ruiqian

2013-01-01

312

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

313

A Simple Statistic for Comparing Moderation of Slopes and Correlations  

Directory of Open Access Journals (Sweden)

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

MichaelSmithson

2012-07-01

314

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

315

Distinguishing the causes of firing with the membrane potential slope.  

Science.gov (United States)

In this letter, we aim to measure the relative contribution of coincidence detection and temporal integration to the firing of spikes of a simple neuron model. To this end, we develop a method to infer the degree of synchrony in an ensemble of neurons whose firing drives a single postsynaptic cell. This is accomplished by studying the effects of synchronous inputs on the membrane potential slope of the neuron and estimating the degree of response-relevant input synchrony, which determines the neuron's operational mode. The measure is calculated using the normalized slope of the membrane potential prior to the spikes fired by a neuron, and we demonstrate that it is able to distinguish between the two operational modes. By applying this measure to the membrane potential time course of a leaky integrate-and-fire neuron with the partial somatic reset mechanism, which has been shown to be the most likely candidate to reflect the mechanism used in the brain for reproducing the highly irregular firing at high rates, we show that the partial reset model operates as a temporal integrator of incoming excitatory postsynaptic potentials and that coincidence detection is not necessary for producing such high irregular firing. PMID:22594827

Koutsou, Achilleas; Christodoulou, Chris; Bugmann, Guido; Kanev, Jacob

2012-09-01

316

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

317

Tolerable Time-Varying Overflow on Grass-Covered Slopes  

Directory of Open Access Journals (Sweden)

Full Text Available Engineers require estimates of tolerable overtopping limits for grass-covered levees, dikes, and embankments that might experience steady overflow. Realistic tolerance estimates can be used for both resilient design and risk assessment. A simple framework is developed for estimating tolerable overtopping on grass-covered slopes caused by slowly-varying (in time overtopping discharge (e.g., events like storm surges or river flood waves. The framework adapts the well-known Hewlett curves of tolerable limiting velocity as a function of overflow duration. It has been hypothesized that the form of the Hewlett curves suggests that the grass erosion process is governed by the flow work on the slope above a critical threshold velocity (referred to as excess work, and the tolerable erosional limit is reached when the cumulative excess work exceeds a given value determined from the time-dependent Hewlett curves. The cumulative excess work is expressed in terms of overflow discharge above a critical discharge that slowly varies in time, similar to a discharge hydrograph. The methodology is easily applied using forecast storm surge hydrographs at specific locations where wave action is minimal. For preliminary planning purposes, when storm surge hydrographs are unavailable, hypothetical equations for the water level and overflow discharge hydrographs are proposed in terms of the values at maximum overflow and the total duration of overflow. An example application is given to illustrate use of the methodology.

Steven A. Hughes

2015-03-01

318

Characterization of Suspended Sediment Load on Three North Slope Rivers  

Science.gov (United States)

Little research has been done to describe the basic characteristics of the majority of rivers on the North Slope of Alaska. The fundamental hydrologic and sedimentologic properties of these rivers is unknown; this coupled with only short-term measurements of precipitation and runoff makes further analysis of the region difficult. Increased human presence on the North Slope makes it imperative to collect basic measurements on these rivers, and to improve the temporal and spatial resolution of data collection. The Anaktuvuk, Itkillik and Chandler Rivers originate in the Brooks Range of Alaska and flow north, joining with the Colville River in the foothills and coastal plain. Frozen for over seven months of the year, all sediment transport must occur during the summer months; the largest hydrologic event is most frequently snowmelt, which begins in late-May in the foothills. The purpose of this study is to gather baseline data on the suspended sediment load of the Anaktuvuk (N 69°27.807', W 151°09.928'), Itkillik (N 68°55.041', W 150°06.776) and Chandler (N 69°16.972', W 151°24.277') rivers. During a field campaign from May to June 2011, suspended sediment samples were collected at regular intervals on all three rivers, using both integrated and grab sampling techniques. The results of these measurements will be presented in an effort to characterize the suspended sediment transport on these three rivers.

Lamb, E. K.; Toniolo, H. A.; Kane, D. L.; Schnabel, W.

2011-12-01

319

Geotechnical properties of cemented sands in steep slopes  

Science.gov (United States)

An investigation into the geotechnical properties specific to assessing the stability of weakly and moderately cemented sand cliffs is presented. A case study from eroding coastal cliffs located in central California provides both the data and impetus for this study. Herein, weakly cemented sand is defined as having an unconfined compressive strength (UCS) of less than 100 kPa, and moderately cemented sand is defined as having UCS between 100 and 400 kPa. Testing shows that both materials fail in a brittle fashion and can be modeled effectively using linear Mohr-Coulomb strength parameters, although for weakly cemented sands, curvature of the failure envelope is more evident with decreasing friction and increasing cohesion at higher confinement. Triaxial tests performed to simulate the evolving stress state of an eroding cliff, using a reduction in confinement-type stress path, result in an order of magnitude decrease in strain at failure and a more brittle response. Tests aimed at examining the influence of wetting on steep slopes show that a 60% decrease in UCS, a 50% drop in cohesion, and 80% decrease in the tensile strength occurs in moderately cemented sand upon introduction to water. In weakly cemented sands, all compressive, cohesive, and tensile strength is lost upon wetting and saturation. The results indicate that particular attention must be given to the relative level of cementation, the effects of groundwater or surficial seepage, and the small-scale strain response when performing geotechnical slope stability analyses on these materials. ?? 2009 ASCE.

Collins, B.D.; Sitar, N.

2009-01-01

320

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

321

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

Science.gov (United States)

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

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

2014-05-01

322

Reversible rock-slope deformations caused by cyclic water-table fluctuations in mountain slopes of the Central Alps, Switzerland  

Science.gov (United States)

Within the framework of the Gotthard Base Tunnel Project in the Central Alps, Switzerland, geodetic monitoring networks were installed above the tunnel trajectory in alpine valleys. Natural ground-surface deformation recorded in the years prior to the tunneling excavation was seen to contain an unexpectedly large cyclical component of horizontal strain across the valleys, which was seasonal and appeared to be due to elastic processes. The strain is strongly correlated with snow melt and rainstorm precipitation, suggesting the implied rock-mass deformation is driven by changes in water-table elevation within adjacent mountain slopes. The horizontal strains are of the order of 1-2 · 10-5, which is close to the design limits that can be accommodated by hydropower arch dams in the study area. This study investigates these processes in detail and describes a new mathematical model (REROD), which is able to accurately reproduce and predict such natural rock-slope displacements. The model implements a transfer-function approach to predict the valley-crossing strains from rainfall and winter snow height data recorded at nearby meteorological stations. It has been used to estimate and remove the natural strain signal from the net recorded deformation so as to resolve the component due to tunneling.

Hansmann, Juergen; Loew, Simon; Evans, Keith F.

2012-02-01

323

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

324

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

325

The Reduction in Drag of a Forward-sloping Windshield  

Science.gov (United States)

This paper gives results of a short investigation of the drag of a forward-sloping closed-cabin windshield. The drag of the windshield in both the original and a final modified form was determined from tests in the variable-density wind tunnel. The final form of the windshield was arrived at by modifying the original as the result of flow observations in the N.A.C.A. smoke tunnel. The investigation studied the utility of the N.A.C.A. smoke tunnel as applied to reducing the drag of objects for which the full dynamic scale could not be approached in the smoke tunnel, but designers should find the results of the flow observations and drag measurements of value. They show that most of the large drag added by the original windshield is eliminated by the modification of the windshield to the final form.

Jacobs, Eastman N

1933-01-01

326

Measurement of the Slope Parameter ? for ? ? 3?^0 decay  

Science.gov (United States)

We report on a new measurement of the slope parameter ? which describes the shape of the ? ? 3?^0 Dalitz plot. The value of the parameter ? provides an important test of chiral perturbation theory. The current Particle Data Group average gives a value for ? about 2 standard deviations higher than theoretical evaluations. The new Crystal Ball result is based on an analysis of a high statistics ( ~ 19× 10^6 decays) sample of ?'s produced at the AGS from the reaction ?^- p ? ? n with a pion beam of momentum 720 MeV/c on a liquid hydrogen target. The statistical error obtained for the parameter ? is several times smaller than for all previous measurements. A study of the systematic uncertanties shows that they are small. Our result will be compared with other experiments, theoretical predictions, and the related KL ? 3?^0 decay.

Prakhov, Serguei

2000-04-01

327

Local slope evolution during thermal annealing of polycrystalline Au films  

International Nuclear Information System (INIS)

The morphological evolution of thermally annealed polycrystalline gold films was studied in terms of several statistical parameters of the growing surface, determined by x-ray diffraction and scanning probe microscopy, including roughness, in-plane and out-of-plane grain size and local slope distributions. The morphology transformations occur as a result of the balance of attractive and repulsive interactions between surface structures emerging at different length scales, which comprise a competition between stress relaxation via surface currents and strain generation. This balance is responsible for the formation of large multigrain structures via the bundling with in-plane reorientation of neighbouring grains, related to attractive interaction on the short length scale, and the generation of grooves and surface discontinuities between structures repelling each other, on longer length scales. These results shed light on the surface phenomena occurring during post-growth annealing of T-zone structured, polycrystalline gold films.

328

Local slope evolution during thermal annealing of polycrystalline Au films  

Science.gov (United States)

The morphological evolution of thermally annealed polycrystalline gold films was studied in terms of several statistical parameters of the growing surface, determined by x-ray diffraction and scanning probe microscopy, including roughness, in-plane and out-of-plane grain size and local slope distributions. The morphology transformations occur as a result of the balance of attractive and repulsive interactions between surface structures emerging at different length scales, which comprise a competition between stress relaxation via surface currents and strain generation. This balance is responsible for the formation of large multigrain structures via the bundling with in-plane reorientation of neighbouring grains, related to attractive interaction on the short length scale, and the generation of grooves and surface discontinuities between structures repelling each other, on longer length scales. These results shed light on the surface phenomena occurring during post-growth annealing of T-zone structured, polycrystalline gold films.

Alonzo-Medina, G. M.; González-González, A.; Sacedón, J. L.; Oliva, A. I.; Vasco, E.

2012-10-01

329

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

330

Slope effects on shortwave radiation components and net radiation  

Science.gov (United States)

The main objective of the International Satellite Land Surface Climatology Project (ISLSCP) has been stated as 'the development of techniques that may be applied to satellite observations of the radiation reflected and emitted from the Earth to yield quantitative information concerning land surface climatological conditions.' The major field study, FIFE (the First ISLSCP Field Experiment), was conducted in 1978-89 to accomplish this objective. Four intensive field campaigns (IFC's) were carried out in 1987 and one in 1989. Factors contributing to observed reflected radiation from the FIFE site must be understood before the radiation observed by satellites can be used to quantify surface processes. Analysis since our last report has focused on slope effects on incoming and outgoing shortwave radiation and net radiation from data collected in 1989.

Walter-Shea, Elizabeth A.; Blad, Blaine L.; Hays, Cynthia J.; Mesarch, Mark A.

1992-01-01

331

Natural gas hydrates on the North Slope of Alaska  

Energy Technology Data Exchange (ETDEWEB)

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

Collett, T.S.

1991-01-01

332

Regional Shoreline Change Along the North Slope of Alaska  

Science.gov (United States)

Climate change impacts to the north coast of Alaska threaten sensitive ecosystems, critical energy-related infrastructure, native Alaskan housing and traditional lifestyles, trust species and their habitats, and large tracts of Federally-managed land. Although there are several site-specific and limited regional studies documenting coastal change along the Beaufort and Chukchi Sea coasts, no comprehensive study has documented coastal change or evaluated its causes on a regional scale. As part of a National Assessment of Shoreline Change study along open-ocean sandy shores of the United States, the U.S. Geological Survey is evaluating shoreline changes along the north slope coast of Alaska between Peard Bay and the Canadian border. Rates of change will be calculated for both the mainland and barrier island coasts using shorelines derived from circa 1947 and 1987 NOS T-sheets and from orthorectified photography and/or satellite imagery collected between 2000 and 2007. Here we present results from the first phase of the study, Colville River to Pt. Thomson, for three time periods (1947, 1987, 2004-7). In contrast to previous independent studies, which have documented localized erosion rates of up to 16 m/yr along portions of Alaska's north slope, results from this study show that on a regional scale, shoreline erosion rates along the mainland coast are typically less than 2 m/yr. The offshore barrier islands, however, are highly dynamic and show high rates of localized shoreline retreat along with a regionally consistent decrease in overall land area and associated rotation and migration to the southwest since the 1940s. As part of this study, continued data collection, analysis, and numerical and analytical modeling of the coast and nearshore environments will provide much needed data sets from which to evaluate future changes along this stretch of coast in response to sea-level rise, variability in the Arctic summer sea-ice extent, increased storminess, and other possible effects of global climate change.

Gibbs, A. E.; Richmond, B. M.; Erikson, L.

2008-12-01

333

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

334

A streamwise view of the Norwegian Atlantic Slope Current  

Science.gov (United States)

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

Chafik, Léon; Nilsson, Johan; Skagseth, Øystein

2013-04-01

335

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

336

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

International Nuclear Information System (INIS)

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

337

Slope geomorphology and processes in four central Svalbard areas - first results of a comparative study relating geomorphological slope features to meteorology, geology and topography  

Science.gov (United States)

Detailed geomorphological mapping has been carried out combining three-dimensional aerial photography studies with detailed field mapping of periglacial slope landforms in selected part of central Svalbard in the Longyearbyen, Adventdalen and Vindodden areas. The focus of the research was on identifying slope processes and their resulting landforms and activity, the meteorological setting and the impact of slope processes on human transport and housing infrastructure of the study areas. The Svalbard landscape has an arctic maritime climate with continuous permafrost and total lack of higher vegetation. The analysed and mapped four study areas range in size and setting concerning distance to the sea and large-scale topographical setting, but they all include slopes and different types of slope deposits. The general Tertiary and Triassic bedrock geology is similar between the areas and consists of almost horizontally laminated layers of sandstones, mudstones and shales. Here we present results of the geomorphological mapping with focus on snow avalanches, debris flows and solifluction processes and sediments. We describe the variable activity and sub-types of the periglacial slope landforms and sediments in relation to meteorological, topographical and geological setting. The major factors constraining type and distribution of slope processes in the four compared areas are suggested to be a combination of bedrock geology of the back walls, location in relation to general wind direction and the sediment composition in the starting areas of debris flows and solifluction sheets.

Rubensdotter, Lena; Christiansen, Hanne; Eckerstorfer, Markus; Farnsworth, Wesley

2013-04-01

338

Ramp Slope Built-in-Self-Calibration Scheme for Single-Slope Column Analog-to-Digital Converter Complementary Metal-Oxide-Semiconductor Image Sensor  

Science.gov (United States)

The conversion gain of a single-slope analog-to-digital converter (ADC) suffers from the process and frequency variations. This ADC gain variation eventually limits the performance of image signal processing (ISP) in a complementary metal-oxide-semiconductor (CMOS) image sensor (CIS). This paper proposes a ramp slope built-in-self-calibration (BISC) scheme for a CIS. The CIS with the proposed BISC was fabricated with a 0.35-?m CMOS process. The measurement results show that the proposed architecture effectively calibrates the ramp slope against the process and the clock frequency variation. The silicon area overhead is less than 0.7% of the full chip area.

Ham, Seogheon; Jung, Wunki; Lee, Dongmyung; Lee, Yonghee; Han, Gunhee

2006-02-01

339

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

340

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

Directory of Open Access Journals (Sweden)

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

Jawdat K. Abbas

2013-04-01

341

Infants’ Perception of Affordances of Slopes Under High and Low Friction Conditions  

OpenAIRE

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 low friction surface was visually distinct from the surrounding high friction surface. In all three experiments, infants could walk down steeper slopes in ...

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

2010-01-01

342

Influence of tibial slope asymmetry on femoral rotation in patients with lateral patellar instability  

OpenAIRE

The geometry of the tibial plateau and its influence on the biomechanics of the tibiofemoral joint has gained increased significance. However, no quantitative data are available regarding the inclination of the medial and lateral tibial slope in patients with patellar instability. It was therefore the purpose of this study to evaluate tibial slope characteristics in patients with patellar dislocations and to assess the biomechanical effect of medial-to-lateral tibial slope asymmetry on latera...

Balcarek, Peter; Terwey, Annika; Jung, Klaus; Walde, Tim; Frosch, Stephan; Schu?ttrumpf, Jan; Wachowski, Martin; Dathe, Henning; Stu?rmer, Klaus

2012-01-01

343

BSR Distribution and Gas Plum in the China Continental Slope Offshore Southwestern Taiwan  

Science.gov (United States)

Widely distributed bottom simulating reflectors (BSR) have been observed in the area offshore southwestern Taiwan where active accretionary complex meets with the passive China continental margin. In order to better understand the distribution and characteristics of the gas hydrate in the region, the Central Geological Survey of Taiwan, ROC carried out a 4-year gas hydrate investigation program starting from 2004. This study reports parts of the marine seismic survey results of that program. Over 2500 km of multichannel seismic (MCS) reflection profile and chirp sonar data were collected in the China continental slope area adjacent to the submarine Taiwan accretionary wedge in 2005. The MCS data consists of 2-D reconnaissance survey profiles with line spacing around 1.85 km, and a 2.5-D intensive survey block where line spacing is less than 400 m. Combined MCS/OBS experiments were conducted in the intensive survey block along selected profiles. Morphologically, the continental slope is consists of several ridges formed by down-slope cutting of submarine canyons. Most of the submarine canyons were developed in the upper slope zone near the shelf-slope break. Seismic profiles reveal that there exists a steeper upper slope zone and a gentle lower slope ridge. BSR were widely distributed in the lower slope ridges. Chirp sonar data suggest that there are many mud volcanoes on top of the slope ridges. Gas plum has also been found on one of the slope ridges by 38 kHz echo sounder. There are complicated structures underneath the slope ridges where BSR are especially strong. We will discuss the gas hydrate distribution characteristics and structural variations in the intensive survey block, and propose the possible fluid migration paths and gas hydrate formation in this passive continental slope area.

Liu, C.; Schnurle, P.; Wang, Y.

2006-12-01

344

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

OpenAIRE

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

Lumholt, Michael; Breinbjerg, Olav

1997-01-01

345

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

OpenAIRE

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 emp...

Sunwen Du; Jin Zhang; Jingtao Li; Qiaomei Su; Wenbo Zhu; Yuejuan Chen

2013-01-01

346

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

OpenAIRE

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

347

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

OpenAIRE

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

348

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

349

Dependence of the Ge(Li) efficiency slope on the source-to-detector distance  

International Nuclear Information System (INIS)

The slope of the linear portion of a Ge(Li) log(efficiency) vs log(energy) plot varies with the source-to-detector distance and crystal geometry. Such considerations should be remembered when applying the empirical function which related this slope to the detector geometry. Such considerations should be remembered when applying the empirical function which relates this slope to the detector active volume. (Auth.)

350

INFLUENCE OF HILLY TERRAIN SLOPE ON THE VOLUME OF ROAD EARTHWORK ??????? ???????????? ????????? ?? ?????? ???????? ???????? ?????  

Directory of Open Access Journals (Sweden)

Full Text Available The analytic dependence for slope correction calculation is obtained. This correction is introduced in the formula for calculating the area of earth roadbed cross-section. It allows detailing the volume of road earthwork at the design stage. The correction size depends on the slope steepness as well as cross-sectional parameters of the earth roadbed. The calculations show that the correction size is essential if ratio of slope is 25 or less

Morkovin V. A.

2012-03-01

351

Net radiation balance for two forested slopes on opposite sides of a valley.  

Science.gov (United States)

Measurements of the net radiation balance of two forested sites on the opposite slopes of a valley in south-western Germany, made over 3 years, are presented in this study. Radiation sensors were mounted horizontally on two measurement towers above two beech stands. The direct part of the measured short-wave incoming radiation was adjusted according to the slope's angle to convert horizontally measured radiation data into surface-parallel radiation fluxes. During periods when contemporaneous measurements of slope-parallel and horizontal radiation fluxes were available, the calculation of surface-parallel radiation fluxes from the horizontally recorded net radiation components were compared with measured values. The net radiative fluxes parallel to the slopes were calculated for a period of 36 months and analysed. Results show that the different aspects of both sites cause significant differences of the net radiation balance. In June, when the elevation of the sun is highest, incoming solar radiation K downward arrow received on the NE-slope was 9% lower than K downward arrow received on the SW-slope. During the winter months, the differences were much greater and incoming solar radiation to the NE-slope was 50% of that to the SW-slope. Due to the differing solar irradiance, net radiation fluxes were significantly higher on the SW-slope than on the NE-slope. For long-wave radiation only small differences between both slopes could be found. Since radiative fluxes determine the energy balance and hence the microclimate and water balance of a forest stand, these differences in the net radiation balance between the slopes are important for the vegetation. PMID:15630573

Holst, T; Rost, J; Mayer, H

2005-05-01

352

Measuring slope to improve energy expenditure estimates during field-based activities  

OpenAIRE

This technical note describes methods to improve activity energy expenditure estimates using a multi-sensor board (MSB) by measuring slope. Ten adults walked over a 2.5-mile course wearing an MSB and mobile calorimeter. Energy expenditure was estimated using accelerometry alone (base) and four methods to measure slope. The barometer and GPS methods improved accuracy 11% from the base (Ps < 0.05) to 86% overall. Measuring slope using the MSB improves energy expenditure estimates during field-b...

Duncan, Glen E.; Lester, Jonathan; Migotsky, Sean; Higgins, Lisa; Borriello, Gaetano

2012-01-01

353

Problems of definitive slopes mining at Doly Nástup Tušimice  

OpenAIRE

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

354

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

355

Study on Setting of Slope Displacement Monitoring Points by Numerical Calculation  

OpenAIRE

Slope displacement monitoring can visually reflect the slope deformation, and reasonable setting of monitoring points is the premise for good monitoring results. At present, the slope displacement monitoring site mostly rely on the experience and the engineering analogous method, which are lack of quantitative analysis. According to the finite difference strength reduction method, get the displacement of distributed monitoring point with the changing of strength reduction coefficient, analyse...

Jie Cheng; Lin Zhu; Xianguo Deng

2013-01-01

356

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

357

Research activities on submarine landslides in gentle continental slope  

Science.gov (United States)

In the north Sanrikuoki Basin off Shimokita Peninsula, NE Japan, a great number of buried large slump deposits have been identified in the Pliocene and younger formations. The basin has formed in a very gentle continental slope of less than one degree in gradient and is composed of well-stratified formations which basically parallel to the present seafloor. This indicates that the slumping have also occurred in such very gentle slope angle. The slump units and their slip surfaces have very simple and clear characteristics, such as layer-parallel slip on the gentle slope, regularly imbricated internal structure, block-supported with little matrix structure, widespread dewatering structure, and low-amplitude slip surface layer. We recognize that the large slump deposits group of layer-parallel slip in this area is an appropriate target to determine 'mechanism of submarine landslides', that is one of the subjects on the new IODP science plan for 2013 and beyond. So, we started some research activities to examine the feasibility of the future scientific drilling. The slump deposits were recognized basically by 3D seismic analysis. Further detailed seismic analysis using 2D seismic data in wider area of the basin is being performed for better understanding of geologic structure of the sedimentary basin and the slump deposits. This will be good source to extract suitable locations for drill sites. Typical seismic features and some other previous studies imply that the formation fluid in this study area is strongly related to natural gas, of which condition is strongly affected by temperature. So, detailed heat flow measurements was performed in the study area in 2013. For that purpose, a long-term water temperature monitoring system was deployed on the seafloor in October, 2012. The collected water temperature variation is applied to precise correction of heat flow values. Vitrinite reflectance analysis is also being carried out using sediments samples recovered by IODP Expedition 337, which is conducted in a part of the study area from July through September in 2012. The values of vitrinite reflectance will be available for modeling thermal history in the sedimentary basin. A science meeting and a field trip were held in Miyazaki Prefecture in September , 2012. At the field trip, we observed typical geologic structures related to slumping and dewatering in Nichinan Group, which are good onshore objects so as to share the aspects of the slump deposits in the Sanrikuoki Basin among the community. This occasion is aimed at sharing better scientific understanding on slumping and related dewatering and also at identifying the issues for planning the scientific drilling. This study uses the 3D seismic data from the METI seismic survey 'Sanrikuoki 3D' in 2008. The seismic analysis, the vitrinite reflectance analysis, and the science meeting and the field excursion in Miyazaki were supported by the foundation of feasibility studies for future IODP scientific drillings by JAMSTEC CDEX in 2012-2013.

Morita, S.; Goto, S.; Miyata, Y.; Nakamura, Y.; Kitahara, Y.; Yamada, Y.

2013-12-01

358

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

DEFF Research Database (Denmark)

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

Lumholt, Michael; Breinbjerg, Olav

1997-01-01

359

Slope orientation assessment for open-pit mines, using GIS-based algorithms  

Science.gov (United States)

Standard stability analysis in geomechanical rock slope engineering for open-pit mines relies on a simplified representation of slope geometry, which does not take full advantage of available topographical data in the early design stages of a mining project; consequently, this may lead to nonoptimal slope design. The primary objective of this paper is to present a methodology that allows for the rigorous determination of interramp and bench face slope orientations on a digital elevation model (DEM) of a designed open pit. Common GIS slope algorithms were tested to assess slope orientations on the DEM of the Meadowbank mining project's Portage pit. Planar regression algorithms based on principal component analysis provided the best results at both the interramp and the bench face levels. The optimal sampling window for interramp was 21×21 cells, while a 9×9-cell window was best at the bench level. Subsequent slope stability analysis relying on those assessed slope orientations would provide a more realistic geometry for potential slope instabilities in the design pit. The presented methodology is flexible, and can be adapted depending on a given mine's block sizes and pit geometry.

Grenon, Martin; Laflamme, Amélie-Julie

2011-09-01

360

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

A Rashid, Ahmad Safuan; Ali, Nazri

2014-01-01

361

The application of fiber Bragg grating in railway slope protection monitoring  

Science.gov (United States)

Taking the monitoring project of slope protection at Wuzhuaguan tunnel portal, Hejiaping segment of Yiwan railway as an example, through the analysis of mechanism of mechanical transmission and failure mode of component of flexible system for protecting slope, we put forward a kind of early warning and alarm system for railway slope protection based on Fiber Bragg Grating sensing technology. Compared with the conventional supervising techniques, the supervising system designed in this work possesses the merits of higher reliability, lower cost, easier to installation, fewer maintenance and so on. This early warning and alarm system can effectively enhance the protecting function of disaster prevention and reduction for railway slope protection.

Hu, Jun; Yuan, Liang-feng; Chen, Hong-bo

2012-01-01

362

Internal soil moisture and piezometric responses to rainfall-induced shallow slope failures  

Science.gov (United States)

SummaryBetter knowledge regarding internal soil moisture and piezometric responses in the process of rainfall-induced shallow slope failures is the key to an effective prediction of the landslide and/or debris flow initiation. To this end, internal soil moisture and piezometric response of 0.7-m-deep, 1.5-m-wide, 1.7-m-high, and 3.94-m-long semi-infinite sandy slopes rested on a bi-linear impermeable bedrock were explored using a chute test facility with artificial rainfall applications. The internal response time defined by the inflection point of the soil moisture and piezometric response curves obtained along the soil-bedrock interface were closely related to some critical failure states, such as the slope toe failure and extensive slope failures. It was also found that the response times obtained at the point of abrupt bedrock slope decrease can be used as indicators for the initiation of rainfall-induced shallow slope failures. An investigation of spatial distributions of soil water content, ? (or degrees of saturation, Sr), in the slope at critical failure states shows that the 0.2 m - below - surface zone remains unsaturated with Sr? 40-60%, regardless of their distances from the toe and the rainfall intensity. Non-uniform distributions of ? (or Sr) along the soil-bedrock interface at critical failure states were always associated with near-saturation states ( Sr? 80-100%) around the point of bedrock slope change or around the transient 'toe' upstream of the slumped mass induced by the retrogressive failure of the slope. These observations suggest the important role of the interflow along the soil-bedrock interface and the high soil water content (or high porewater pressure) around the point of bedrock slope deflection in the rainfall-induced failure of sandy slopes consisting of shallow impermeable bedrocks. The present study proposes an 'internal response time' criterion to substantiate the prediction of rainfall-induced shallow slope failures. It is believed that the 'internal response time' reflects the overall characteristics of a slope under rainfall infiltration and can be as useful as the conventional meteorology-based threshold times. The 'internal response time' theory can be generalized via numerical modeling of slope hydrology, slope geology and slope stability in the future.

Ching-Chuan, Huang; Yih-Jang, Ju; Lih-Kang, Hwu; Jin-Long, Lee

2009-05-01

363

Geotechnical characteristics and slope stability on the Ebro margin, western Mediterranean  

Science.gov (United States)

Sedimentological and geotechnical analyses of core samples from the Ebro continental slope define two distinct areas on the basis of sediment type, physical properties and geotechnical behavior. The first area is the upper slope area (water depths of 200-500 m), which consists of upper Pleistocene prodeltaic silty clay with a low water content (34% dry weight average), low plasticity, and high overconsolidation near the seafloor. The second area, the middle and lower slope (water depths greater than 500 m), contains clay- and silt-size hemipelagic deposits with a high water content (90% average), high plasticity, and a low to moderate degree of overconsolidation near the sediment surface. Results from geotechnical tests show that the upper slope has a relatively high degree of stability under relatively rapid (undrained) static loading conditions, compared with the middle and lower slopes, which have a higher degree of stability under long-term (drained) static loading conditions. Under cyclic loading, which occurs during earthquakes, the upper slope has a higher degree of stability than the middle and lower slopes. For the surface of the seafloor, calculated critical earthquake accelerations that can trigger slope failures range from 0.73 g on the upper slope to 0.23 g on the lower slope. Sediment buried well below the seafloor may have a critical acceleration as low as 0.09 g on the upper slope and 0.17 g on the lower slope. Seismically induced instability of most of the Ebro slope seems unlikely given that an earthquake shaking of at least intensity VI would be needed, and such strong intensities have never been recorded in the last 70 years. Other cyclic loading events, such as storms or internal waves, do not appear to be direct causes of instability at present. Infrequent, particularly strong earthquakes could cause landslides on the Ebro margin slope. The Columbretes slide on the southwestern Ebro margin may have been caused by intense earthquake shaking associated with volcanic emplacement of the Columbretes Islands. Localized sediment slides on steep canyon and levee slopes could have been caused by less intense shaking. In general, the slope is stable under present environmental loading conditions and is fundamentally constructional. Nevertheless, rapid progradation caused by high sedimentation rates and other processes acting during low sea-level periods, such as more intense wave loading near the shelfbreak, may have caused major instability in the past. ?? 1990.

Baraza, J.; Lee, H.J.; Kayen, R.E.; Hampton, M.A.

1990-01-01

364

Circulation over the shelf and slope off northern California  

Science.gov (United States)

Hydrographic observations taken during the Northern California Coastal Circulation Study (NCCCS) are analyzed to examine the structure and variability of density and velocity over the shelf and slope, to a distance of 70 km offshore and a depth of 1500 m. Cross-shore sections with closely spaced stations were occupied between the Oregon border and San Francisco seven times between March 1987 and October 1989. Historical observations from CaICOFI line 60 off Point Reyes are also analyzed to provide better resolution of seasonal and interannual variability in the region than is available from the NCCCS data. Poleward flow dominates the circulation in this easternmost part of the California Current system, much more so than the historical description would indicate. Because there is substantial poleward shear below 500-m depth, poleward transports in the top 500 m referred to 1500-m depth are 2 to 5 times the values referred to 500 m. Equatorward flow occurs on average over the shelf, and in an organized fashion offshore. The shelf flows appear to be the local response to wind-driven upwelling. The offshore equatorward flow is an energetic, narrow feature that persists for several months at a time and has alongshore structure aligned to the shape of the coastline. It can be identified in one of the NCCCS surveys as the same jet described by the 1988 Coastal Transition Zone experiment observations. Empirical Orthogonal Function analysis indicates that seasonal variability in the top 500 m of the water column generally explains less variance (˜20%) than does interannual variability (˜50%). Between 500 and 1500 m, seasonal fluctuations explain a greater proportion of the variance (˜50%). The shape of the coastline, the coastal mountains, and the bathymetry of the shelf and slope have a significant influence on the circulation in this region. There is enhanced upwelling near the two major capes (Mendocino and Point Arena), as well as substantial increases in poleward transports near both. Flow is directed offshore on the north sides of both features and onshore to the south. The equatorward flowing offshore jet is found closer to shore in the embayment between the two capes and farther offshore at the latitude of the capes.

Bray, N. A.; Greengrove, C. L.

1993-10-01

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

Measures of spectral slope using an excised larynx model.  

Science.gov (United States)

Spectral measures of the glottal source were investigated using an excised canine larynx (CL) model for various aerodynamic and phonatory conditions. These measures included spectral harmonic difference H1-H2 and spectral slope that are highly correlated with voice quality but not reported in a systematic manner using an excised larynx model. It was hypothesized that the acoustic spectra of the glottal source were significantly influenced by the subglottal pressure, glottal adduction, and vocal fold elongation, as well as the resulting vibration pattern. CLs were prepared, mounted on the bench with and without false vocal folds, and made to oscillate with a flow of heated and humidified air. Major control parameters were subglottal pressure, adduction, and elongation. Electroglottograph, subglottal pressure, flow rate, and audio signals were analyzed using custom software. Results suggest that an increase in subglottal pressure and glottal adduction may change the energy balance between harmonics by increasing the spectral energy of the first few harmonics in an unpredictable manner. It is suggested that changes in the dynamics of vocal fold motion may be responsible for different spectral patterns. The finding that the spectral harmonics do not conform to previous findings was demonstrated through various cases. Results of this study may shed light on phonatory spectral control when the larynx is part of a complete vocal tract system. PMID:22056893

Alipour, Fariborz; Scherer, Ronald C; Finnegan, Eileen

2012-07-01

367

Temperature statistics above a deep-ocean sloping boundary  

CERN Document Server

We present a detailed analysis of the statistics of temperature in an oceanographic observational dataset. The data is collected using a moored array of thermistors, 100m tall and starting 5m above the bottom, deployed during four months above the slopes of a seamount in the North Eastern Atlantic Ocean. Turbulence at this location is strongly affected by the semidiurnal tidal wave. Mean stratification is stable in the entire dataset. We compute structure functions, of order up to 10, of the distributions of temperature increments. Strong intermittency is observed in particular during the downslope phase of the tide, and farther from the solid bottom. In the lower half of the mooring during the upslope phase, the statistics of temperature are consistent with those of a passive scalar. In the upper half of the mooring, the statistics of temperature deviate from those of a passive scalar, and evidence of turbulent convective activity is found. The downslope phase is generally thought to be more shear dominated,...

Cimatoribus, Andrea A

2015-01-01

368

Estimated prospective tanker rates for Alaska North Slope crude oil  

International Nuclear Information System (INIS)

Within the next ten years, three significant events will affect the structure of tankering costs for the Alaska North Slope (ANS) oil fields. These are: the double hulling requirement of the Oil Spill Pollution Act of 1990 (OPA90); the ageing of the tanker fleet; and the decline in ANS and West Coast oil production, which will eliminate more costly shipments to the Gulf Coast. The purpose of this paper is to estimate how these will affect tankering costs over the next twenty years. As baseline, the existing fleet is described, followed by a detailed discussion of the above factors. Company specific shipping requirements are calculated as compared to ship-by-ship tonnage availability (based on the current fleet) pursuant to these events, and the resultant tonnage deficit. A model is presented that derives a hypothetical reconstruction scheme to eliminate the deficits on a company specific ship-by-ship basis. The resulting costs are then translated into a weighted average per barrel ANS cost. The specific double hull costs are segregated. (author)

369

Slope-aspect color shading for parametric surfaces  

Science.gov (United States)

The invention is a method for generating an image of a parametric surface, such as the compass direction toward which each surface element of terrain faces, commonly called the slope-aspect azimuth of the surface element. The method maximizes color contrast to permit easy discrimination of the magnitude, ranges, intervals or classes of a surface parameter while making it easy for the user to visualize the form of the surface, such as a landscape. The four pole colors of the opponent process color theory are utilized to represent intervals or classes at 90 degree angles. The color perceived as having maximum measured luminance is selected to portray the color having an azimuth of an assumed light source and the color showing minimum measured luminance portrays the diametrically opposite azimuth. The 90 degree intermediate azimuths are portrayed by unique colors of intermediate measured luminance, such as red and green. Colors between these four pole colors are used which are perceived as mixtures or combinations of their bounding colors and are arranged progressively between their bounding colors to have perceived proportional mixtures of the bounding colors which are proportional to the interval's angular distance from its bounding colors.

Moellering, Harold J. (Inventor); Kimerling, A. Jon (Inventor)

1991-01-01

370

Regional variability of slope stability: Application to the Eel margin, California  

Science.gov (United States)

Relative values of downslope driving forces and sediment resisting forces determine the locations of submarine slope failures. Both of these vary regionally, and their impact can be addressed when the data are organized in a Geographic Information System (GIS). The study area on the continental margin near the Eel River provides an excellent opportunity to apply GIS spatial analysis techniques for evaluation of slope stability. In this area, swath bathymetric mapping shows seafloor morphology and distribution of slope steepness in fine detail, and sediment analysis of over 70 box cores delineates the variability of sediment density near the seafloor surface. Based on the results of ten geotechnical studies of submarine study areas, we developed an algorithm that relates surface sediment density to the shear strength appropriate to the type of cyclic loading produced by an earthquake. Strength and stress normalization procedures provide results that are conceptually independent of subbottom depth. Results at depth are rigorously applicable if sediment lithology does not vary significantly and consolidation state can be estimated. Otherwise, the method applies only to shallow-seated slope failure. Regional density, slope, and level of anticipated seismic shaking information were combined in a GIS framework to yield a map that illustrates the relative stability of slopes in the face of seismically induced failure. When a measure of predicted relative slope stability is draped on an oblique view of swath bathymetry, a variation in this slope stability is observed on an otherwise smooth slope along the mid-slope region north of a plunging anticline. The section of slope containing diffuse, pockmarked gullies has a lower measure of stability than a separate section containing gullies that have sharper boundaries and somewhat steeper sides. Such an association suggests that our slope-stability analysis relates to the stability of the gully sides. The remainder of the study area shows few obvious indications of slope instability except for a feature that has become known as the 'Humboldt Slide,' but it is too deep-seated to be amenable to the slope-stability-prediction techniques presented herein. In general, few slope failures have been mapped in the Eel margin study area despite the high level of seismicity, the relatively high rates of sediment accumulation, and the extent of gas charging observed by others.

Lee, H.; Locat, J.; Dartnell, P.; Israel, K.; Florence, Wong

1999-01-01

371

On the Antarctic Slope Front and Current crossing of the South Scotia Ridge  

Science.gov (United States)

To unveil the contorted path followed by the Antarctic Slope Current connecting the Weddell and Scotia Seas, hydrographic stations with unprecedented spatial resolution were occupied on a series of sections across the slope and multiple channels in the double-pronged western portion of the South Scotia Ridge. Fieldwork consisted of two cruises from the ESASSI (January 2008) and ACROSS (February 2009) programs, the Spanish and USA/Argentina components of the International Polar Year core project SASSI (Synoptic Antarctic Shelf-Slope Interaction study). In this region the Antarctic Slope Current can be located by the pronounced in-shore deepening of isopycnals over the continental slope, rendering the strong subsurface temperature and salinity gradients characteristic of the Antarctic Slope Front. Before reaching the gaps in the southern Ridge near 51°W and 50°W, the ASC carries about 3 Sv of upper layer waters, but it splits into shallow and deep branches upon turning north through these two gaps. The shallower branch enters the Hesperides Trough at 51°W, then shows a tight cyclonic loop back to that longitude roughly following the slope's 700-m isobath, and turns again westward through a similar gap in the northern Ridge. In the Scotia Sea the westward-flowing Antarctic Slope Current is found as far west as the Elephant Island along slightly deeper levels of slope (1100 m) before it is blocked by the Antarctic Circumpolar Current south of the Shackleton Fracture Zone (56°W). The deeper branch of the ASC in the Powell Basin crosses the southern Ridge near 50°W and roughly follows the 1600-m isobath before entering the Scotia Sea through the Hesperides Gap farther to the east (49°W). Thereafter the deeper waters carried westward by this branch become undistinguishable from those circulating farther offshore. Repeat cross-slope sections at both southern and northern flanks of the South Scotia Ridge showed significant temporal variability in the characteristics of the Antarctic Slope Front/Current system.

Orsi, A. H.; Palmer, M.; Gomis, D.; Flexas, M. M.; Kim, Y.-S.; Jordà, G.; Wiederwohl, C.; Álvarez, M.

2012-04-01

372

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

Science.gov (United States)

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.

Murakami, S.; Dairaku, A.; Komine, H.; Sakai, N.; Isizawa, T.; Saito, O.; Maruyama, I.

2013-06-01

373

Comparison of Student Understanding of Line Graph Slope in Physics and Mathematics  

Science.gov (United States)

This study gives an insight into the differences between student understanding of line graph slope in the context of physics (kinematics) and mathematics. Two pairs of parallel physics and mathematics questions that involved estimation and interpretation of line graph slope were constructed and administered to 114 Croatian second year high school…

Planinic, Maja; Milin-Sipus, Zeljka; Katic, Helena; Susac, Ana; Ivanjek, Lana

2012-01-01

374

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

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

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

Science.gov (United States)

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

Burt, Jennifer Williamson

2012-03-01

377

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

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

Developing restoration planting mixes for active ski slopes: a multi-site reference community approach.  

Science.gov (United States)

Downhill ski areas occupy large expanses of mountainous lands where restoration of ecosystem function is of increasing importance and interest. Establishing diverse native plant communities on ski runs should enhance sediment and water retention, wildlife habitat, biodiversity and aesthetics. Because ski slopes are managed for recreation, ski slope revegetation mixes must consist of low-stature or herbaceous plants that can tolerate typical environmental conditions on ski slopes (high elevation, disturbed soils, open, steep slopes). The most appropriate reference communities for selecting ski slope revegetation species are thus successional, or seral plant communities in similar environments (i.e., other ski slopes). Using results from a broad-scale reference community analysis, I evaluated plant communities naturally occurring on ski slopes from 21 active and abandoned ski areas throughout the northern Sierra Nevada to identify native plant species suitable for use in ski slope restoration. I constructed a baseline planting palette of regionally appropriate plant species (for restoration of either newly created or already existing ski runs) that is functionally diverse and is likely to succeed across a broad range of environments. I also identify a more comprehensive list of species for more specialized planting mixes based on site-specific goals and particular environmental settings. Establishing seral plant communities may be an appropriate restoration goal for many other types of managed lands, including roadsides, firebreaks and utility rights-of-way. This study describes an ecological (and potentially cost-effective) approach to developing restoration planting palettes for such managed lands. PMID:22245855

Burt, Jennifer Williamson

2012-03-01

380

Systematic of the slope-mass-correlations in diffractive dissociation reactions  

International Nuclear Information System (INIS)

A set of several results of the Three Components Deck Model for Diffractive Dissociation Reactions is presented. News and recently published results are summarized to obtain a general overview of the model, its predictions and comparison with experimental results. Two kinds of correlations and amplitudes are given: The slope-mass cos theta sup(GJ) correlation and slope-mass partial wave. (Author)

381

Experimental Observations On Turbidity Currents Flowing Over Low Bed Slopes  

Science.gov (United States)

Turbidity currents are gravity-driven, sediment-laden turbulent flows moving on a sloping bottom, which take place in oceans and lakes. Due to the difficulties to predict and observe this kind of phenomena in nature, in the recent past many experimental apparatus were set up to increase the comprehension of the currents. We developed an experimental apparatus able to reproduce such kind of currents in our Marchi Environmental Laboratory. The experiments were performed in an horizontal flume U shaped in plan, 30 m long, characterized by two straight tracks approximately 12 m in length, and a bend with a constant radius of curvature equal to 2.5 m. The flume, made in plexiglass, has a rectangular cross section 0.6 m wide and 0.5 m deep. The particular shape of the channel let us study the spatial development of turbidity (or saline) currents in the straight reach and the adjustment of the flow in the channel bend. We have created a concrete fixed bed with an uniform bottom slope of 0.005 developing both along the first straight and the constant curvature bend and continuing 3 meters after the bend exit. The first set of experimental observations were performed employing an 'hybrid' turbidity current, in that the density excess was created by adding both salt and fine sediments (d50=4 micron) to clear water. Each run, characterized by the same initial and boundary conditions (fractional density excess, discharge of the mixture, inlet and outlet conditions) and by the same geometry, was repeated many times in order to measure vertical velocity and density profiles in different cross sections along the straight and bend reaches. Both longitudinal and lateral velocity measurements were performed, as well as density profiles. The velocity profiles were acquired using an ultrasound Doppler velocimeter profiler. In this way we recorded the longitudinal velocity in the channel axis with a spatial resolution of 1 m along the flume and, coupling the data of two probes aligned in the cross section with different angles, we were able to obtain the vertical profiles of the secondary flow in the central region of the flume. The density profiles were obtained using two ranks of siphons that take samples of the current water at different heights from the bottom. The ongoing experimental observations will allow to provide detailed measurements on both flow velocity and suspended sediment concentration of subcritical turbidity currents flowing in constant curvature bend and shed some light on the ongoing debate concerning the orientation of secondary flow in submarine channels. At present we have completed the first set of runs, performed with a flow discharge Q=2 l/s and a density of the mixture ?_{mix}=1021 kg/m^3 that provides a relative excess density equal to 0,023. The current was subcritical both in the straight and curved reach and characterized by an average densimetric Froude number approximately equal to 0.70. Secondary flow in the curved bend was characterized by a river like orientation, i.e. inward oriented close to the bed and outward oriented above. In the next sets of experiments we plan to perform further runs by changing the density of the mixture and the flow discharge in order to observe their effect on the evolution of the turbidity current. These further results will be hopefully presented at the meeting.

Stagnaro, M.; Bolla Pittaluga, M.

2012-12-01

382

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

383

Economics of Alaska North Slope gas utilization options  

International Nuclear Information System (INIS)

The recoverable natural gas available for sale in the developed and known undeveloped fields on the Alaskan North Slope (ANS) total about 26 trillion cubic feet (TCF), including 22 TCF in the Prudhoe Bay Unit (PBU) and 3 TCF in the undeveloped Point Thomson Unit (PTU). No significant commercial use has been made of this large natural gas resource because there are no facilities in place to transport this gas to current markets. To date the economics have not been favorable to support development of a gas transportation system. However, with the declining trend in ANS oil production, interest in development of this huge gas resource is rising, making it important for the U.S. Department of Energy, industry, and the State of Alaska to evaluate and assess the options for development of this vast gas resource. The purpose of this study was to assess whether gas-to-liquids (GTL) conversion technology would be an economic alternative for the development and sale of the large, remote, and currently unmarketable ANS natural gas resource, and to compare the long term economic impact of a GTL conversion option to that of the more frequently discussed natural gas pipeline/liquefied natural gas (LNG) option. The major components of the study are: an assessment of the ANS oil and gas resources; an analysis of conversion and transportation options; a review of natural gas, LNG, and selected oil product markets; and an economic analysis of the LNG and GTL gas sales options based on publicly available input needed for assumptions of the economic variables. Uncertainties in assumptions are evaluated by determining the sensitivity of project economics to changes in baseline economic variables

384

Exporting Alaskan North Slope crude oil: Benefits and costs  

International Nuclear Information System (INIS)

The Department of Energy study examines the effects of lifting the current prohibitions against the export of Alaskan North Slope (ANS) crude. The study concludes that permitting exports would benefit the US economy. First, lifting the ban would expand the markets in which ANS oil can be sold, thereby increasing its value. ANS oil producers, the States of California and Alaska, and some of their local governments all would benefit from increased revenues. Permitting exports also would generate new economic activity and employment in California and Alaska. The study concludes that these economic benefits would be achieved without increasing gasoline prices (either in California or in the nation as a whole). Lifting the export ban could have important implications for US maritime interests. The Merchant Marine Act of 1970 (known as the Jones Act) requires all inter-coastal shipments to be carried on vessels that are US-owned, US-crewed, and US-built. By limiting the shipment of ANS crude to US ports only, the export ban creates jobs for the seafarers and the builders of Jones Act vessels. Because the Jones Act does not apply to exports, however, lifting the ban without also changing US maritime law would jeopardize the jobs associated with the current fleet of Jones Act tankers. Therefore the report analyzes selected economic impacts of several maritime policy alternatives, including: Maintaining current law, which allows foreign tankers to carry oil where export is allowed; requiring exports of ANS crude to be carried on Jones Act vessels; and requiring exports of ANS crude to be carried on vessels that are US-owned and US-crewed, but not necessarily US-built. Under each of these options, lifting the export ban would generate economic benefits

385

Economics of Alaska North Slope gas utilization options  

Energy Technology Data Exchange (ETDEWEB)

The recoverable natural gas available for sale in the developed and known undeveloped fields on the Alaskan North Slope (ANS) total about 26 trillion cubic feet (TCF), including 22 TCF in the Prudhoe Bay Unit (PBU) and 3 TCF in the undeveloped Point Thomson Unit (PTU). No significant commercial use has been made of this large natural gas resource because there are no facilities in place to transport this gas to current markets. To date the economics have not been favorable to support development of a gas transportation system. However, with the declining trend in ANS oil production, interest in development of this huge gas resource is rising, making it important for the U.S. Department of Energy, industry, and the State of Alaska to evaluate and assess the options for development of this vast gas resource. The purpose of this study was to assess whether gas-to-liquids (GTL) conversion technology would be an economic alternative for the development and sale of the large, remote, and currently unmarketable ANS natural gas resource, and to compare the long term economic impact of a GTL conversion option to that of the more frequently discussed natural gas pipeline/liquefied natural gas (LNG) option. The major components of the study are: an assessment of the ANS oil and gas resources; an analysis of conversion and transportation options; a review of natural gas, LNG, and selected oil product markets; and an economic analysis of the LNG and GTL gas sales options based on publicly available input needed for assumptions of the economic variables. Uncertainties in assumptions are evaluated by determining the sensitivity of project economics to changes in baseline economic variables.

Thomas, C.P.; Doughty, T.C.; Hackworth, J.H.; North, W.B.; Robertson, E.P.

1996-08-01

386

Exporting Alaskan North Slope crude oil: Benefits and costs  

Energy Technology Data Exchange (ETDEWEB)

The Department of Energy study examines the effects of lifting the current prohibitions against the export of Alaskan North Slope (ANS) crude. The study concludes that permitting exports would benefit the US economy. First, lifting the ban would expand the markets in which ANS oil can be sold, thereby increasing its value. ANS oil producers, the States of California and Alaska, and some of their local governments all would benefit from increased revenues. Permitting exports also would generate new economic activity and employment in California and Alaska. The study concludes that these economic benefits would be achieved without increasing gasoline prices (either in California or in the nation as a whole). Lifting the export ban could have important implications for US maritime interests. The Merchant Marine Act of 1970 (known as the Jones Act) requires all inter-coastal shipments to be carried on vessels that are US-owned, US-crewed, and US-built. By limiting the shipment of ANS crude to US ports only, the export ban creates jobs for the seafarers and the builders of Jones Act vessels. Because the Jones Act does not apply to exports, however, lifting the ban without also changing US maritime law would jeopardize the jobs associated with the current fleet of Jones Act tankers. Therefore the report analyzes selected economic impacts of several maritime policy alternatives, including: Maintaining current law, which allows foreign tankers to carry oil where export is allowed; requiring exports of ANS crude to be carried on Jones Act vessels; and requiring exports of ANS crude to be carried on vessels that are US-owned and US-crewed, but not necessarily US-built. Under each of these options, lifting the export ban would generate economic benefits.

1994-06-01

387

GPU Accelerated Numerical Simulation of Viscous Flow Down a Slope  

Science.gov (United States)

Numerical simulations are an effective tool in natural risk analysis. They are useful to determine the propagation and the runout distance of gravity driven movements such as debris flows or landslides. To evaluate these processes an approach on analogue laboratory experiments and a GPU accelerated numerical simulation of the flow of a viscous liquid down an inclined slope is considered. The physical processes underlying large gravity driven flows share certain aspects with the propagation of debris mass in a rockslide and the spreading of water waves. Several studies have shown that the numerical implementation of the physical processes of viscous flow produce a good fit with the observation of experiments in laboratory in both a quantitative and a qualitative way. When considering a process that is this far explored we can concentrate on its numerical transcription and the application of the code in a GPU accelerated environment to obtain a 3D simulation. The objective of providing a numerical solution in high resolution by NVIDIA-CUDA GPU parallel processing is to increase the speed of the simulation and the accuracy on the prediction. The main goal is to write an easily adaptable and as short as possible code on the widely used platform MATLAB, which will be translated to C-CUDA to achieve higher resolution and processing speed while running on a NVIDIA graphics card cluster. The numerical model, based on the finite difference scheme, is compared to analogue laboratory experiments. This way our numerical model parameters are adjusted to reproduce the effective movements observed by high-speed camera acquisitions during the laboratory experiments.

Gygax, Remo; Räss, Ludovic; Omlin, Samuel; Podladchikov, Yuri; Jaboyedoff, Michel

2014-05-01

388

Turbulent Bore Wave Propagation on a Linear Sloping Beach  

Science.gov (United States)

Turbulent bore waves formed after wave breaking on beaches have been studied in the field with natural incident waves and in laboratory wave tanks for monochromatic incident wave spectra. The present research attempts to extend previous results both by focussing on broadband incident wave spectra and by looking carefully at the evolution of the turbulent bores in a highly instrumented wave tank. In our current research, turbulent bores are generated in the Max Hammond Wave Tank at SRI with a 1:25 sloped linear beach by two types of incident spectra: a monochromatic sine wave spectrum for repeatable experiments and a JONSWAP spectra (gamma=3.3) for more realistic incident waves. Instrumentation employed for measurement of bore propagation includes: 20 capacitive wave height gauges, a Ku-band Doppler radar and simultaneous video recording. There is also both a surface PIV and volume PIV capability for reconstructing fluid flow in the bore wave volume and on the surface but these measurements are not included in the experiments reported here. We have also developed a wavefront tracking algorithm that retrieves bore propagation velocity from the video imagery as a function of position. In this paper, we present measurements of the phase speed of bore waves as a function of bottom depth for a range of wave breaker types from gentle spillers to violent plungers for both monochromatic and JONSWAP broadband incident spectra. Our results are compared with shallow-water Boussinesq model predictions. The goals of this research are to improve prediction of turbulent bore waves in realistic conditions and develop remote sensing techniques for retrieving bathymetry and other surf-zone properties of the nearshore environment.

Weiss, J. M.; Piccirillo, P. B.; Tremain, D. E.; Orwoll, M.; Abdou, I.

2002-12-01

389

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

390

Hydrological heterogeneity in Mediterranean reclaimed slopes: runoff and sediment yield at the patch and slope scales along a gradient of overland flow  

Science.gov (United States)

Hydrological heterogeneity is recognized as a fundamental ecosystem attribute in drylands controlling the flux of water and energy through landscapes. Therefore, mosaics of runoff and sediment source patches and sinks are frequently identified in these dry environments. There is a remarkable scarcity of studies about hydrological spatial heterogeneity in restored slopes, where ecological succession and overland flow are interacting. We conducted field research to study the hydrological role of patches and slopes along an "overland flow gradient" (gradient of overland flow routing through the slopes caused by different amounts of run-on coming from upslope) in three reclaimed mining slopes of Mediterranean-continental climate. We found that runoff generation and routing in non-rilled slopes showed a pattern of source and sink areas of runoff. Such hydrological microenvironments were associated with seven vegetation patches (characterized by plant community types and cover). Two types of sink patches were identified: shrub Genista scorpius patches could be considered as "deep sinks", while patches where the graminoids Brachypodium retusum and Lolium perenne dominate were classified as "surface sinks" or "runoff splays". A variety of source patches were also identified spanning from "extreme sources" (Medicago sativa patches; equivalent to bare soil) to "poor sources" (areas scattered by dwarf-shrubs of Thymus vulgaris or herbaceous tussocks of Dactylis glomerata). Finally, we identified the volume of overland flow routing along the slope as a major controlling factor of "hydrological diversity" (heterogeneity of hydrological behaviours quantified as Shannon diversity index): when overland flow increases at the slope scale hydrological diversity diminishes.

Merino-Martín, L.; Moreno-de las Heras, M.; Pérez-Domingo, S.; Espigares, T.; Nicolau, J. M.

2012-05-01

391

Influence of filling-drawdown cycles of the Vajont reservoir on Mt. Toc slope stability  

Science.gov (United States)

In the present work, the 1963 Vajont landslide has been back-analyzed in detail to examine the influence of reservoir operations (filling and drawdown) on Mt. Toc slope stability. The combined seepage-slope stability analyses carried out show that the main destabilizing factor that favored the 1963 Vajont landslide was the reservoir-induced water table that formed as a consequence of rapid seepage inflow within the submerged toe of the slope — decrease in the factor of safety (FOS) up to 12% compared to the initial slope stability condition, i.e., in the absence of the Vajont reservoir. Rainfall would only have been a decisive factor if the initial stability condition of the Mt. Toc slope had already been very close to failure (decrease in FOS caused by heavy or prolonged rainfall is about 3-4%, for the worst case scenario analyzed). The permeability of the shear zone material occurring at the base of the prehistoric Vajont rockslide has been evaluated at 5 × 10- 4 m/s, and back-calculated values of the friction angles ? range from 17.5° to 27.5°. When considering mountain reservoirs, slope failures can occur during both filling and drawdown phases. In the Vajont case, owing to the highly permeable materials of the shear zone, slope stability decreased during filling and increased during drawdown. Another displacement-dependent phenomenon of a mechanical nature - progressive failure of the NE landslide constraint - has to be considered to understand the slope collapse that occurred during the last drawdown (26 September-9 October 1963). The results of the combined seepage-slope stability models indicate that permeability of bank-forming material and filling-drawdown rates of reservoirs can strongly influence slope stability. Slow lowering of the reservoir level is a necessary measure to reduce the occurrence of very dangerous transient negative peaks of FOS.

Paronuzzi, Paolo; Rigo, Elia; Bolla, Alberto

2013-06-01

392

Slope Failure Records in Gas Hydrate Bearing Regions of the Cascadia Margin  

Science.gov (United States)

ODP Leg 204 (Hydrate Ridge region) and IODP Exp. 311 (offshore Vancouver Island) cores and site survey seismic reflection profiles reveal that seismically defined wedges observed in the slope basins adjacent to gas hydrate bearing ridges correspond to intervals of more frequent slope failure compared to the surrounding hemipelagic sediments. Both Sites 1251B, 1252A and 1325B show multiple intervals of increased slope failure that are separated by periods of slow hemipelagic sedimentation. Rather than single submarine landslide deposits, these intervals are composed of multiple sand/silt turbidites and debris flows, which are most easily observed as relative increases in magnetic susceptibility, due to the abundant detrital magnetic mineral grains found within them. Core descriptions coupled with the magnetic susceptibility data for both Leg 204 and Exp. 311 cores document apparent temporal cyclicity to these episodes of slope failure. At Sites 1251B and 1252A, which can be correlated to each other, and at Site 1325B, four major episodes of increased slope failure are observed. These data coupled with initial radiocarbon ages and diatom biostratigraphy (Watanabe, 2006 and Akiba et al., 2009) suggest that the slope failure cycles may change on glacial-interglacial timescales. Dramatic changes in sea level driven by glacial-interglacial ice sheet dynamics often regulates the frequency of slope failure near the shelf-slope break in high latitude, non-sediment starved continental margins like Cascadia. Slope failures along active continental margins can also be triggered by seismic events (Goldfinger et al., 2003); indeed, Holocene subduction zone earthquakes on the Cascadia margin are known to trigger slope failures every 500-600 years, a frequency that varies on long tectonic timescales rather than glacial-interglacial periods. These mechanisms, however, do not explain the long timescale cyclic records of slope failure in these regions. Sites 1251, 1252, and 1325, lie in portions of the margin that are generally isolated from shelf and submarine canyon sediment sources and are located near the toe of the accretionary wedge where they predominantly receive local sediment loads from the erosion of the surrounding gas hydrate bearing bathymetric highs. In this presentation, new TOC measurements, radiocarbon ages, and carbon and oxygen isotope data help characterize the stratigraphy at these sites and constrain the timing of these major slope failure episodes. The implications for the mechanisms responsible for these slope failure variations and their potential relationship to the local gas hydrate systems will also be discussed.

Johnson, J. E.; Torres, M. E.; Hong, W.; Disenhof, C.; Miranda, E.; Rose, K.

2010-12-01

393

Automating slope monitoring in mines with terrestrial lidar scanners  

Science.gov (United States)

Static terrestrial laser scanners (TLS) have been an important component of slope monitoring for some time, and many solutions for monitoring the progress of a slide have been devised over the years. However, all of these solutions have required users to operate the lidar equipment in the field, creating a high cost in time and resources, especially if the surveys must be performed very frequently. This paper presents a new solution for monitoring slides, developed using a TLS and an automated data acquisition, processing and analysis system. In this solution, a TLS is permanently mounted within sight of the target surface and connected to a control computer. The control software on the computer automatically triggers surveys according to a user-defined schedule, parses data into point clouds, and compares data against a baseline. The software can base the comparison against either the original survey of the site or the most recent survey, depending on whether the operator needs to measure the total or recent movement of the slide. If the displacement exceeds a user-defined safety threshold, the control computer transmits alerts via SMS text messaging and/or email, including graphs and tables describing the nature and size of the displacement. The solution can also be configured to trigger the external visual/audio alarm systems. If the survey areas contain high-traffic areas such as roads, the operator can mark them for exclusion in the comparison to prevent false alarms. To improve usability and safety, the control computer can connect to a local intranet and allow remote access through the software's web portal. This enables operators to perform most tasks with the TLS from their office, including reviewing displacement reports, downloading survey data, and adjusting the scan schedule. This solution has proved invaluable in automatically detecting and alerting users to potential danger within the monitored areas while lowering the cost and work required for monitoring. An explanation of the entire system and a post-acquisition data demonstration will be presented.

Conforti, Dario

2014-05-01

394

Modelling the seasonal variability of the Antarctic Slope Current  

Directory of Open Access Journals (Sweden)

Full Text Available One of the main features of the oceanic circulation along Antarctica is the Antarctic Slope Current (ASC. This circumpolar current flows westwards and contributes to communication between the three major oceanic basins around Antarctica. The ASC is not very well known due to remote location and the presence of sea ice during several months, allowing in situ studies only during summertime. Moreover, only few modelling studies of this current have been carried out. Here, we investigate the sensitivity of this simulated current to four different resolutions in a coupled ocean-sea ice model and to two different atmospheric forcing sets. Two series of simulations are conducted. For the first series, global model configurations are run at coarse (2° to eddy-permitting (0.25° resolutions with the same atmospheric forcing. For the second series, simulations with two different atmospheric forcings are performed using a regional circumpolar configuration (south of 30° S at 0.5° resolution. The first atmospheric forcing is based on a global atmospheric reanalysis and satellite data, while the second is based on a downscaling of the global atmospheric reanalysis by a regional atmospheric model calibrated to Antarctic meteorological conditions.

Sensitivity experiments to resolution indicate that a minimum model resolution of 0.5° is needed to capture the dynamics of the ASC in terms of water mass transport and recirculation. Sensitivity experiments to atmospheric forcing fields shows that the wind speed along the Antarctic coast strongly controls the water mass transport and the seasonal cycle of the ASC. An increase in annual mean of easterlies by about 30 % leads to an increase in the mean ASC transport by about 40 %. Similar effects are obtained on the seasonal cycle: using a wind forcing field with a larger seasonal cycle (+30 % increases by more than 30 % the amplitude of the seasonal cycle of the ASC. To confirm the importance of wind seasonal cycle, a simulation without wind speed seasonal cycle is carried out. This simulation shows a decrease by more than 50 % of the amplitude of the ASC transport seasonal cycle without changing the mean value of ASC transport.

P. Mathiot

2011-07-01

395

Modelling the variability of the Antarctic Slope Current  

Directory of Open Access Journals (Sweden)

Full Text Available One of the main features of the oceanic circulation along Antarctica is the Antarctic Slope Current (ASC. This circumpolar current flows westward and allows communication between the three major basins around Antarctica. The ASC is not very well known due to difficult access and the presence of sea ice during several months, allowing in situ study only during summertime. Moreover, only few numerical studies of this current have been carried out. Here, we investigate the sensitivity of this current to two different atmospheric forcing sets and to four different resolutions in a coupled ocean-sea ice model (NEMO-LIM. Two sets of simulation are conducted. For the first set, global model configurations are run at coarse (2° to eddy permitting resolutions (0.25° with the same atmospheric forcing. For the second set, simulations with two different atmospheric forcing sets are performed with a regional circumpolar configuration (south of 30° S at 0.5° resolution. The first atmospheric forcing set is based on ERA40 reanalysis and CORE data, while the second one is based on a downscaling of the reanalysis ERA40 by the MAR regional atmospheric model.

Sensitivity experiments to resolution show that a minimum model resolution of 0.5° is needed to capture the dynamics of the ASC in term of transport and recirculation. Sensitivity of the ASC to atmospheric forcing fields shows that the wind speed along the Antarctic coast strongly controls the transport and the seasonal cycle of the ASC. An increase of the Easterlies by about 30% leads to an increase of the mean transport of ASC by about 40%. Similar effects are obtained on the seasonal cycle: using a forcing fields with a stronger amplitude of the seasonal cycle leads to double the amplitude of the seasonal cycle of the ASC. To confirm the importance of the wind speed, a simulation, where the seasonal cycle of the wind speed is removed, is carried out. This simulation shows a decrease by more than 50% of the amplitude of the seasonal cycle without changing the mean value of ASC transport.

P. Mathiot

2011-01-01

396

Minimal Power Latch for Single-Slope ADCs  

Science.gov (United States)

Column-parallel analog-to-digital converters (ADCs) for imagers involve simultaneous operation of many ADCs. Single-slope ADCs are well adapted to this use because of their simplicity. Each ADC contains a comparator, comparing its input signal level to an increasing reference signal (ramp). When the ramp is equal to the input, the comparator triggers a latch that captures an encoded counter value (code). Knowing the captured code, the ramp value and hence the input signal are determined. In a column-parallel ADC, each column contains only the comparator and the latches; the ramp and code generation are shared. In conventional latch or flip-flop circuits, there is an input stage that tracks the input signal, and this stage consumes switching current every time the input changes. With many columns, many bits, and high code rates, this switching current can be substantial. It will also generate noise that may corrupt the analog signals. A latch was designed that does not track the input, and consumes power only at the instant of latching the data value. The circuit consists of two S-R (set-reset) latches, gated by the comparator. One is set by high data values and the other by low data values. The latches are cross-coupled so that the first one to set blocks the other. In order that the input data not need an inversion, which would consume power, the two latches are made in complementary polarity. This requires complementary gates from the comparator, instead of complementary data values, but the comparator only triggers once per conversion, and usually has complementary outputs to begin with. An efficient CMOS (complementary metal oxide semiconductor) implementation of this circuit is shown in the figure, where C is the comparator output, D is the data (code), and Q0 and Q1 are the outputs indicating the capture of a zero or one value. The latch for Q0 has a negative-true set signal and output, and is implemented using OR-AND-INVERT logic, while the latch for Q1 uses positive- true signals and is implemented using AND-OR-INVERT logic. In this implementation, both latches are cleared when the comparator is reset. Two redundant transistors are removed from the reset side of each latch, making for a compact layout. CMOS imagers with column-parallel ADCs have demonstrated high performance for remote sensing applications. With this latch circuit, the power consumption and noise can be further reduced. This innovation can be used in CMOS imagers and very-low-power electronics

Hancock, Bruce R.

2013-01-01

397

Modelling the variability of the Antarctic Slope Current  

Science.gov (United States)

One of the main features of the oceanic circulation along Antarctica is the Antarctic Slope Current (ASC). This circumpolar current flows westward and allows communication between the three major basins around Antarctica. The ASC is not very well known due to difficult access and the presence of sea ice during several months, allowing in situ study only during summertime. Moreover, only few numerical studies of this current have been carried out. Here, we investigate the sensitivity of this current to two different atmospheric forcing sets and to four different resolutions in a coupled ocean-sea ice model (NEMO-LIM). Two sets of simulation are conducted. For the first set, global model configurations are run at coarse (2°) to eddy permitting resolutions (0.25°) with the same atmospheric forcing. For the second set, simulations with two different atmospheric forcing sets are performed with a regional circumpolar configuration (south of 30° S) at 0.5° resolution. The first atmospheric forcing set is based on ERA40 reanalysis and CORE data, while the second one is based on a downscaling of the reanalysis ERA40 by the MAR regional atmospheric model. Sensitivity experiments to resolution show that a minimum model resolution of 0.5° is needed to capture the dynamics of the ASC in term of transport and recirculation. Sensitivity of the ASC to atmospheric forcing fields shows that the wind speed along the Antarctic coast strongly controls the transport and the seasonal cycle of the ASC. An increase of the Easterlies by about 30% leads to an increase of the mean transport of ASC by about 40%. Similar effects are obtained on the seasonal cycle: using a forcing fields with a stronger amplitude of the seasonal cycle leads to double the amplitude of the seasonal cycle of the ASC. To confirm the importance of the wind speed, a simulation, where the seasonal cycle of the wind speed is removed, is carried out. This simulation shows a decrease by more than 50% of the amplitude of the seasonal cycle without changing the mean value of ASC transport.

Mathiot, P.; Goosse, H.; Fichefet, T.; Barnier, B.; Gallée, H.

2011-01-01

398

Comprehensive Stability Evaluation of Rock Slope Using the Cloud Model-Based Approach  

Science.gov (United States)

This article presents the cloud model-based approach for comprehensive stability evaluation of complicated rock slopes of hydroelectric stations in mountainous area. This approach is based on membership cloud models which can account for randomness and fuzziness in slope stability evaluation. The slope stability is affected by various factors and each of which is ranked into five grades. The ranking factors are sorted into four categories. The ranking system of slope stability is introduced and then the membership cloud models are applied to analyze each ranking factor for generating cloud memberships. Afterwards, the obtained cloud memberships are synthesized with the factor weights given by experts for comprehensive stability evaluation of rock slopes. The proposed approach is used for the stability evaluation of the left abutment slope in Jinping 1 Hydropower Station. It is shown that the cloud model-based strategy can well consider the effects of each ranking factor and therefore is feasible and reliable for comprehensive stability evaluation of rock slopes.

Liu, Zaobao; Shao, Jianfu; Xu, Weiya; Xu, Fei

2014-11-01

399

QRS slopes for assessment of myocardial damage in chronic chagasic patients  

International Nuclear Information System (INIS)

In this study the slopes of the QRS complex are evaluated for determination of the degree of myocardial damage in chronic chagasic patients. Previous studies have demonstrated the ability of the slope indices to reflect alterations in the conduction velocity of the cardiac impulse. Results obtained in the present study show that chronic chagasic patients have significantly flatter QRS slopes as compared to healthy subjects. Not only that but the extent of slope lessening turns out to be proportional to the degree of myocardial damage caused by the disease. Additionally, when incorporating the slope indices into a classification analysis together with other indices indicative of the presence of ventricular late potentials obtained from high resolution electrocardiography, results show that the percentages of correct classification increase up to 62.5%, which means eight points above the percentages obtained prior to incorporation of the slope indices. It can be concluded that QRS slopes have great potential for assessing the degree of severity associated with Chagas' disease

400

Predicting reading outcomes with progress monitoring slopes among middle grade students.  

Science.gov (United States)

Effective implementation of response-to-intervention (RTI) frameworks depends on efficient tools for monitoring progress. Evaluations of growth (i.e., slope) may be less efficient than evaluations of status at a single time point, especially if slopes do not add to predictions of outcomes over status. We examined progress monitoring slope validity for predicting reading outcomes among middle school students by evaluating latent growth models for different progress monitoring measure-outcome combinations. We used multi-group modeling to evaluate the effects of reading ability, reading intervention, and progress monitoring administration condition on slope validity. Slope validity was greatest when progress monitoring was aligned with the outcome (i.e., word reading fluency slope was used to predict fluency outcomes in contrast to comprehension outcomes), but effects varied across administration conditions (viz., repeated reading of familiar vs. novel passages). Unless the progress monitoring measure is highly aligned with outcome, slope may be an inefficient method for evaluating progress in an RTI context. PMID:24659899

Tolar, Tammy D; Barth, Amy E; Fletcher, Jack M; Francis, David J; Vaughn, Sharon

2014-02-01