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1
Brüninghaus, Jan, Anna Oster e Bernd Kuhlenkötter. "Accuracy and Material Properties in Incremental Forming for a Multi-Step Expanding Approach". Key Engineering Materials 639 (marzo 2015): 179–86. http://dx.doi.org/10.4028/www.scientific.net/kem.639.179.
Testo completoAbstract (sommario):
In incremental sheet forming the material properties change dependent on the wall angle. In addition to sheet thinning, material hardening can be observed and for stainless steel the formation of strain induced martensite has been reported. These process characteristics have been extensively examined for the forming of parts in one step. In this study, a first investigation is made to control the material properties independent on the wall angle by a multi-step expanding approach. For this, in the first step a steep wall angle is formed and in the following steps this region is transformed to a shallow wall angle, keeping the material properties. To demonstrate and verify this new approach a small cone frustum with a wall angle of 60° was formed as a preform. This cone frustum was repeatedly expanded in steps of 2° to get finally a cone frustum with 30° wall angle. The stepwise expanding causes a considerably growing of the shape in depth direction, especially at the preformed area. By a heuristic approach the geometric accuracy of the final cone was optimized. The microhardness measurement of the formed cones shows that the final cone frustum has a region, where the material properties are similar to the first formed 60° wall angle. By this new approach the possibility to influence the material properties of the final part purely by tool path is demonstrated. In particular it is possible to form regions with shallow wall angles that have the material properties of regions with steep wall angles.
2
Purnomo, Dhika Aditya, Fipka Bisono e Rizal Indrawan. "Analysis of Threshold Angle Variations on The Quality of Finishing Free-form Surface in CNC Milling Process". International Journal of Science, Engineering and Information Technology 6, n. 2 (31 luglio 2022): 318–22. http://dx.doi.org/10.21107/ijseit.v6i2.14952.
Testo completoAbstract (sommario):
The machining process using a combination of steep and shallow strategy is the most widely used strategy for the finishing process on complex models that have many areas of steep walls and shallow floors. Using a single machining strategy on the entire model can lead to long machining times and poor surface finish quality. The steep and shallow strategy can efficiently detect parts of the model that have steep contours and those that have shallow contours. In other words, this strategy can analyze the model surface angle at runtime to identify and divide the machining zone based on the slope angle or commonly called the threshold angle. In this context, the selection of the threshold angle is very important when carrying out the finishing process on free-form surfaces to produce a good surface quality. This study was conducted to determine the optimum threshold angle that can produce the minimum surface roughness between steep areas and shallow areas. Threshold angles that were varied were 20°, 30° and 40°. Machining was carried out using Ballnose type cutting tools with a diameter of 6 mm. Then the stepover and stepdown is 0.1 mm for the finishing process on the surface of the propeller product made of Aluminum by using a CNC Milling machine. From the experimental results, the most optimum threshold angle is at an angle of 40° with an average roughness value in the steep area of 1.9 mm and in the shallow area of 1.3mm and a total average roughness of 1.6mm.
3
Sun, Zhicheng, Aoyu Zhang, Xiaotong Li e Yuan Xue. "Test Analysis of 220 kV Rotating Transmission Angle Tower". Journal of Physics: Conference Series 2557, n. 1 (1 luglio 2023): 012031. http://dx.doi.org/10.1088/1742-6596/2557/1/012031.
Testo completoAbstract (sommario):
Abstract As the requirements for the protection of environmental water in the construction of transmission lines have increased, the position of the tower in steep mountainous areas often fails to meet the requirements because of the difference in tower legs, which causes damage to the original landform, thus resulting in the change of the path and the increase of the project investment. In this paper, we optimize the design of a rotating steel tower to adapt to the steep terrain of mountainous areas and reduce the base surface opening. The feasibility of the proposed rotating tower optimization design is demonstrated by analyzing the real test data of the rotating tower.
4
Gilbert, Kenneth E. "Wide-angle formulation of the Beilis-Tappert method". Journal of the Acoustical Society of America 152, n. 2 (agosto 2022): 1170–79. http://dx.doi.org/10.1121/10.0013727.
Testo completoAbstract (sommario):
The theory and numerical examples are given for a wide-angle formulation of the Beilis-Tappert method for wave propagation over irregular terrain. The vertical wave number k in the Beilis-Tappert method is not a physical wave number. Consequently, an essential but previously unknown element of the Beilis-Tappert method is the need to use a slope-dependent k-space vertical wave number filter. The filter selects the physical vertical wave numbers in k-space integrals. The importance of the vertical wave number filter (“ k-control”) is demonstrated theoretically and numerically for propagation over a steep hill and over a shallow hill. For the steep hill, it is shown that k-control is as important as the extension to wide angles. For the shallow hill, k-control and the wide-angle extension are much less important, so that, for some applications, the original narrow-angle formulation gives acceptable accuracy.
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Makarov, V. N., V. Ya Potapov, N. V. Makarov e A. V. Ugolnikov. "GENESIS OF EFFICIENCY OF STEEP ANGLE CONVEYOR BELTS". MINING INFORMATIONAL AND ANALYTICAL BULLETIN 5 (2018): 165–70. http://dx.doi.org/10.25018/0236-1493-2018-5-0-165-170.
Testo completo
6
Loye, A., M. Jaboyedoff e A. Pedrazzini. "Identification of potential rockfall source areas at a regional scale using a DEM-based geomorphometric analysis". Natural Hazards and Earth System Sciences 9, n. 5 (8 ottobre 2009): 1643–53. http://dx.doi.org/10.5194/nhess-9-1643-2009.
Testo completoAbstract (sommario):
Abstract. The availability of high resolution Digital Elevation Models (DEM) at a regional scale enables the analysis of topography with high levels of detail. Hence, a DEM-based geomorphometric approach becomes more accurate for detecting potential rockfall sources. Potential rockfall source areas are identified according to the slope angle distribution deduced from high resolution DEM crossed with other information extracted from geological and topographic maps in GIS format. The slope angle distribution can be decomposed in several Gaussian distributions that can be considered as characteristic of morphological units: rock cliffs, steep slopes, footslopes and plains. A terrain is considered as potential rockfall sources when their slope angles lie over an angle threshold, which is defined where the Gaussian distribution of the morphological unit "Rock cliffs" become dominant over the one of "Steep slopes". In addition to this analysis, the cliff outcrops indicated by the topographic maps were added. They contain however "flat areas", so that only the slope angles values above the mode of the Gaussian distribution of the morphological unit "Steep slopes" were considered. An application of this method is presented over the entire Canton of Vaud (3200 km2), Switzerland. The results were compared with rockfall sources observed on the field and orthophotos analysis in order to validate the method. Finally, the influence of the cell size of the DEM is inspected by applying the methodology over six different DEM resolutions.
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Glen, F., A. C. Broderick, B. J. Godley, J. D. Metcalfe e G. C. Hays. "Dive angles for a green turtle (Chelonia mydas)". Journal of the Marine Biological Association of the United Kingdom 81, n. 4 (agosto 2001): 683–86. http://dx.doi.org/10.1017/s0025315401004374.
Testo completoAbstract (sommario):
The depth and swim speed of a green turtle (Chelonia mydas) were measured during the internesting period in Cyprus. For dives to the seabed (U-dives) we used these data to determine dive angles. Typically the turtle initially descended at a steep angle (∼60°) but as the dive continued this angle lessened until the turtle approached the seabed at an average angle of ∼15°. This systematic change in descent angle is consistent with the prediction that the energetic implications of dive angle are most important at the start of the dive when the turtle is fighting to overcome its positive buoyancy. On leaving the seabed, the turtle often seemed to rise passively.
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Wesley, Laurence D. "Coulomb wedge analysis of cuts in steep slopes". Canadian Geotechnical Journal 38, n. 6 (1 dicembre 2001): 1354–59. http://dx.doi.org/10.1139/t01-049.
Testo completoAbstract (sommario):
Coulomb's trial wedge method for estimating the active force on retaining walls is applied to situations where there are steep slopes at limiting equilibrium behind the walls. The analysis is applied initially to slopes of dry cohesionless material; in this case the slope angle is equal to the friction angle of the material. The analysis produces two interesting, and perhaps surprising, results. The first is that the critical wedge angle equals the slope angle, and the critical wedge becomes a "slab" extending an unlimited distance up the slope above the wall. The second is that as the inclination of the slope and friction angle (which are equal) increase the active force on the wall decreases. The method is then applied to more general slopes involving cohesion, friction, and seepage. Back-analysis is first used to obtain combinations of cohesion and friction corresponding to limiting equilibrium; these are then used in the wedge analysis. The results obtained are similar to those for the dry cohesionless slope. The method provides a means of estimating required retaining forces for cuts made in steep slopes of residual soil or partly weathered rock where estimation of strength parameters is often very difficult.Key words: slopes, steep, back-analysis, Coulomb, wedge, analysis.
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Hong, Yung-Shan, Rong-Her Chen, Cho-Sen Wu e Jian-Ren Chen. "Shaking table tests and stability analysis of steep nailed slopes". Canadian Geotechnical Journal 42, n. 5 (1 ottobre 2005): 1264–79. http://dx.doi.org/10.1139/t05-055.
Testo completoAbstract (sommario):
Shaking table tests were performed on five model slopes to examine the effects of the angle and length of the nails and the frequency of excitation on the seismic resistance and failure mechanism of the slopes. Seismic excitation was also applied to slopes at various angles. Experimental results showed that nails markedly improved the seismic resistance of all model steep slopes. Additionally, nailed slopes exhibit characteristics of ductility under strong excitation. The angle of the nails influences the deformation of the slope but only slightly affects seismic resistance. An increase in the length of the nails increased the seismic resistance of the slope and reduced the displacement of the facing only when subjected to strong excitation. The slope at an angle of 90° to the horizontal has a markedly lower seismic resistance than that at 80°. The rocking of the model slope was strong for the slope with inclined nails and the slope at 90° to the horizontal. The failure surface of the soil mass is approximately a bilinear surface; the pullout of nails from the lower rows of nails caused total slope failure. The seismic resistance of a nailed slope is categorized viz. response of the models by three stages: stable, seismic resistance, and incipient collapse phases. Critical seismic acceleration coefficients of all models are evaluated and compared with values predicted by a developed pseudo-static, limit-equilibrium-based slope stability approach, which postulates a two-wedge failure mechanism.Key words: shaking table test, steep nailed slope, seismic resistance, pseudo-static approach.
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Majidov, Takhir, e Nazir Ikramov. "Influence of flow hydraulic characteristics on the ridge lower escarpment angle". E3S Web of Conferences 264 (2021): 03015. http://dx.doi.org/10.1051/e3sconf/202126403015.
Testo completoAbstract (sommario):
In the riverbeds and canals that run on non-cohesive grounds, bedload sediments move in the ridges form. Ridge forms determine the flow rate of bedload sediments, hydraulic resistances, the types and rates of deformations in alluvial channels. The main elements of ridge formations are height, gentle and steep length with corresponding escarpments. The ridge's steep length and this corresponding escarpment change with changes in the flow hydraulic characteristics. With a change in the ridge's steep length and its steep escarpment, the hydraulic resistance of the channel, the flow rate of bedload sediments, the types, and the channel deformation rates change. In the laboratory, a series of experiments with different sediments compositions and diameters were carried out on the hydraulic tray to determine the main elements (total, gentle and steep length, and the ridge height) and the dynamic characteristics of the ridge formations and the flow hydraulic characteristics. Calculation formulas for determining the coefficient of the ridge lower escarpments with and without taking into account the angle of the natural ground escarpment under water and in the dry state, and the dependence of the steepness of the relative ridge on the relative flow velocity, are obtained. The obtained dependencies allow to accurately determine the geometric and dynamic characteristics of bedload ridges and the corresponding hydraulic characteristics that may define the view ridge formations, ridges resistance of the channel, and the flow rate of bedload sediments, and to design sustainable escarpments large channels.
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King, David A. "The Functional Significance of Leaf Angle in Eucalyptus". Australian Journal of Botany 45, n. 4 (1997): 619. http://dx.doi.org/10.1071/bt96063.
Testo completoAbstract (sommario):
The genus Eucalyptus L’Herit. contains a large proportion of species with nearly vertical foliage, as well as species with shallower leaf angles. This review uses the observation that species with steeply inclined foliage have concolorous leaves (same colour on both sides) to assess the broad patterns of leaf angle across the natural range of Eucalyptus. Species with shallow-angled leaves are shown to be largely restricted to areas of moderate to high rainfall and mild to warm climates along the margins of Australia where they co-occur with steeper-leaved species. A review of patterns in leaf angle on other continents and the functional significance of this trait supports the commonly held view that vertical leaves have been selected to reduce midday heat loads, thereby increasing water use efficiency and hence carbon gain, in eucalypts of dry interior regions. However, steep-leaved species also dominate the wetter, more productive montane forests of south-eastern Australia and Tasmania. In this case, vertical foliage may increase the competitive ability of individuals through a number of mechanisms, including the more efficient interception of light for the low sun angles prevalent at high latitudes, and by somewhat ameliorating low leaf temperatures during still, clear nights, thus decreasing subsequent cold-associated photoinhibition.
12
Fang, Hui, Bin Xu, Wei Chen, Hairong Tang e Shiping Zhao. "A Slope-Adapted Sample-Tilting Method for Profile Measurement of Microstructures with Steep Surfaces". Journal of Nanomaterials 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/253062.
Testo completoAbstract (sommario):
This paper presents a slope-adapted sample-tilting method for the profile measurement of microstructures with steep surfaces. Distinct from the traditional scanning method that has the restriction of a maximum detectable angle, this method corrects the sample-stylus relative angle during the measurement of the steep surface to eliminate the profile deviation and the scanning blind region. The performance of the proposed method was verified by simulations that measured the surface profiles of a trapezoidal microstructure and a spherical microstructure, finding maximum errors of 0.15 μm and 1.71 μm, respectively, compared to 3.63 μm and 7.85 μm using the traditional scanning method. The proposed method enables accurate profile measurement and quality control of microstructures with steep surfaces.
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Manuel, J. L., e Michael J. Dadswell. "Swimming behavior of juvenile giant scallop, Placopecten magellanicus, in relation to size and temperature". Canadian Journal of Zoology 69, n. 8 (1 agosto 1991): 2250–54. http://dx.doi.org/10.1139/z91-315.
Testo completoAbstract (sommario):
Juvenile scallops (shell height 4–35 mm) were stimulated to swim in an aquarium using a whelk, and their swimming was recorded and analyzed using a videocassette recorder. Scallops ascended in the water column in straight, spiral, or twisting patterns, and the majority never swam horizontally. Two types of swimming were observed. Stable swimming, with a consistent body angle (the angle that the scallop makes with the horizon), was recorded over the size range of scallops examined. In stepwise swimming, the body angle alternated between steep (98 ± 13 (SD)) and more horizontal angles (51 ± 9°). Stepwise swimming was observed among the smaller (mean ± SD = 8 ± 3 mm) scallops. Maximum and mean velocities were positively correlated with both shell height and temperature. Clap rate (Cr) increased with increasing temperature (Cr = 0.29T (°C) + 1.3). Body angle expressed a significant relationship with shell height. Below 10 mm shell height the mean angle was 82°; between 30 and 35 mm the mean angle was 38°.
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Al-Baghdadi, Nadher Hassan. "STABILIZATION OF EARTH SLOPES BY USING SOIL NAILING". Kufa Journal of Engineering 5, n. 1 (15 gennaio 2014): 1–12. http://dx.doi.org/10.30572/2018/kje/511237.
Testo completoAbstract (sommario):
The basic concept of soil nailing is to reinforce and strengthen the existing round by installing closely spaced steel bars, called “Nails”, into a slope as construction proceeds from “top-down”. This process creates a reinforced section that is in itself stable and able to retain the ground behind it. Soil nailing technique is used to support new very steep cuts with advantage of strengthening the slope with excessive earth works to provide construction access and working associated with commonly used retaining systems. In the present research work a parametric study has been made using commercial computer program “Slide 6“, which utilize different methods for solving slope stability problem, Bishop method has been used herein to analyze un nailed and nailed slopes with granular soil, different slope heights and angles have been considered. Some of nails parameters have been studied herein, positions of nail, length of nail, angle of nail inclination, and nail spacing. The optimum length of nail depends on height and angle of slope. The optimum angle of nail is found to be ranged between (10-25) degree down from the horizon, but it’s also relates with the angle of slope. The spacing of nail was found to be (1 m) to give the best improvement of F.S.
15
Dou, Xiujie, Silvania F. Pereira, Changjun Min, Yuquan Zhang, Peiwen Meng, H. Paul Urbach e Xiaocong Yuan. "Determination of steep sidewall angle using polarization-sensitive asymmetric scattering". Measurement Science and Technology 32, n. 8 (17 maggio 2021): 085201. http://dx.doi.org/10.1088/1361-6501/abfbac.
Testo completo
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Choi, C. E., C. W. W. Ng, G. R. Goodwin, L. H. D. Liu e W. W. Cheung. "Flume investigation of the influence of rigid barrier deflector angle on dry granular overflow mechanisms". Canadian Geotechnical Journal 53, n. 10 (ottobre 2016): 1751–59. http://dx.doi.org/10.1139/cgj-2015-0248.
Testo completoAbstract (sommario):
Mass-wasting processes are often intercepted using rigid barriers, which are sometimes equipped with deflectors to prevent overspilling. Despite the engineering value of deflectors, they are currently only installed using empirical and prescriptive approaches because flow interaction mechanisms are not well understood. A 5 m flume was used to study dry granular flow deposition and overflow processes with and without deflectors of varying angles. The deflector angle was varied as 0°, 30°, 45°, and 60° with respect to the horizontal plane. For the geometric and material parameters adopted in this study, experimental results reveal that deflector angles greater than 45° develop steep ramp-like deadzones that result in effective energy dissipation as approaching flow impacts the deflector, whereas deflectors less than 45° rapidly develop shallow ramp-like deadzones, which promote high-energy overflow. Deflectors of at least 45° are required to develop upward overflow launch angles, whilst deflectors of 30° or less result in downward overflow launch angles. Upward launch angles indicate that a steep deadzone develops and effectively dissipates flow energy. An orthogonal deflector increases launch lengths by 40% compared to a bare rigid barrier.
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Shragge, Jeff. "Angle-domain common-image gathers in generalized coordinates". GEOPHYSICS 74, n. 3 (maggio 2009): S47—S56. http://dx.doi.org/10.1190/1.3103248.
Testo completoAbstract (sommario):
The theory of angle-domain common-image gathers (ADCIGs) is extended to migrations performed in generalized 2D coordinate systems. I have developed an expression linking the definition of reflection opening angle to differential traveltime operators and spatially varying weights derived from the non-Cartesian geometry. Generalized-coordinate ADCIGs can be calculated directly using Radon-based offset-to-angle approaches for coordinate systems satisfying the Cauchy-Riemann differentiability criteria. The canonical examples of tilted-Cartesian, polar, and elliptical coordinates can be used to illustrate the ADCIG theory. I have compared analytically and numerically generated image volumes for a set of elliptically shaped reflectors. Experiments with a synthetic data set showed that elliptical-coordinate ADCIGs better resolve the reflection opening angles of steeply dipping structure, relative to conventional Cartesian image volumes, because of improved large-angle propagation and enhanced sensitivity to steep structural dips afforded by coordinate system transformations.
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Gold, Colin, Scott Seaman e Satoshi Yamaguchi. "Relationship between odontoid fracture angle and cervical sagittal balance". Surgical Neurology International 12 (14 aprile 2021): 157. http://dx.doi.org/10.25259/sni_829_2020.
Testo completoAbstract (sommario):
Background: Fractures can occur in various locations within the odontoid process with differing orientations. However, little is known about what factors contribute to the anterior versus posterior angles/orientation of these fractures. Methods: We evaluated 74 patients with odontoid fractures (2013–2018) from a single-institution. Patients’ fracture angles/orientations were measured on computed tomography studies, and were grouped into oblique posterior (OP) or oblique anterior (OA) groups. We also took into account cervical sagittal balance utilizing upright x-rays. Other variables studied included patients’ ages, sagittal balance measurements, and the mechanisms of injury. Results: Fracture angles were significantly steeper in the OP group. OP fractures had larger C2-C7 sagittal vertical axis, occiput-C2 angles, and occiput-C7 angles versus anteriorly oriented fractures. In our linear regression model, advanced age and large occiput-C2 angles were predictive of the odontoid fracture angle. Patients who sustained ground-level falls also had significantly steeper fracture angles versus those involved in motor vehicle accidents. Conclusion: The odontoid tends to fracture at a steep, posterior angle in elderly patients who demonstrate a large positive sagittal balance when the head is extended following a ground-level falls.
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Jia, Xiaofeng, e Ru-Shan Wu. "Superwide-angle one-way wave propagator and its application in imaging steep salt flanks". GEOPHYSICS 74, n. 4 (luglio 2009): S75—S83. http://dx.doi.org/10.1190/1.3124686.
Testo completoAbstract (sommario):
One-way wave propagators have been used extensively in forward and inverse problems. The advantages of one-way wave propagators are the fast speed of computation and the large savings in computer resources. However, regular one-way wave propagators have inherent angle limitation to within 90° of the preferred direction (e.g., [Formula: see text]-direction). We propose to overcome the limitation by a superwide-angle one-way method, which combines and interpolates two orthogonally propagated one-way wavefields in the 2D case. A weight function determined by the propagation angle is employed to combine the two one-way wavefields. In the current implementation, we use the wavefield gradient to estimate the propagation angle. Numerical experiments show that the proposed method has accurate superwide-angle [Formula: see text] propagation and can model turning waves well. By applying the superwide-angle one-way wave propagator on several synthetic model data sets, we can demonstrate the validity of the method in imaging steep and overhanging salt flanks.
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Amazonas, Daniela, Jessé C. Costa, Jörg Schleicher e Reynam Pestana. "Wide-angle FD and FFD migration using complex Padé approximations". GEOPHYSICS 72, n. 6 (novembre 2007): S215—S220. http://dx.doi.org/10.1190/1.2785813.
Testo completoAbstract (sommario):
Seismic migration by downward continuation using the one-way wave-equation approximations has two shortcomings: imaging steep-dip reflectors and handling evanescent waves. Complex Padé approximations allow a better treatment of evanescent modes, stabilizing finite-difference migration without requiring special treatment for the migration domain boundaries. Imaging of steep-dip reflectors can be improved using several terms in the Padé expansion. We discuss the implementation and evaluation of wide-angle complex Padé approximations for finite-difference and Fourier finite-difference migration methods. The dispersion relation and the impulsive response of the migration operator provide criteria to select the number of terms and coefficients in the Padé expansion. This ensures stability for a prescribed maximum propagation direction. The implementations are validated on the Marmousi model data set and SEG/EAGE salt model data.
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MOSTAFA, M. B., N. A. SENNA, A. M. ABU-SEIDA e Y. M. ELEMMAWY. "Evaluation of Abnormal Limb Conformation in Jumping Thoroughbred Horses". Journal of the Hellenic Veterinary Medical Society 70, n. 2 (12 luglio 2019): 1533. http://dx.doi.org/10.12681/jhvms.20859.
Testo completoAbstract (sommario):
Subjective, objective and photographic image using software Auto CAD programme were used for evaluation of limb conformation in 51 jumping thoroughbred horses. The abnormal limb conformations were included: standing under in front (58%), steep shoulder (55%), carpus valgus (45%), calf knee (31%), standing under behind (31%), short pelvis (31%) and straight hocks (16%). Linear and angular limb measurements showed standing under in front had increased elbow joint lateral angle, and decreased fore fetlock joint lateral angle. Steep shoulder displayed a significant increase (P< 0.05) in shoulder joint lateral angle and significant decrease in forearm front length. calf knee horses had significant decrease in the lateral angle of carpus joint. Short pelvis had a significant decrease in lateral length of pelvis and significant increase in croup angle and stifle joint lateral angle. Straight hocks showed the lateral length of both pelvis and gaskin showed a significant decrease and significant increase in the stifle joint lateral angle. Therefore, the current use of linear and angular measurements in relationships to abnormal limb conformation in the present study will allow for estimation of the future performance and soundness in jumping thoroughbred horses. In addition can be considered for selection athletic horse with less risk of lameness.
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Grujić, Miloš, e Dragana Erdeljan. "Advantages of High Angle Belt Conveyors (Hac) in Mining". Applied Mechanics and Materials 683 (ottobre 2014): 73–77. http://dx.doi.org/10.4028/www.scientific.net/amm.683.73.
Testo completoAbstract (sommario):
Increased depth in the mines looking for steep conveyor path. The classic means of transportation are not able to cope with high gradients. This paper discusses the advantages of belt conveyors with a high angle of inclination in the application of the mines. On that occasion, and give some lessons learned.
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Nishimura, Yuki, e Tomoyuki Yamaguchi. "Grass Cutting Robot for Inclined Surfaces in Hilly and Mountainous Areas". Sensors 23, n. 1 (3 gennaio 2023): 528. http://dx.doi.org/10.3390/s23010528.
Testo completoAbstract (sommario):
Grass cutting is necessary to prevent grass from diverting essential nutrients and water from crops. Usually, in hilly and mountainous areas, grass cutting is performed on steep slopes with an inclination angle of up to 60° (inclination gradient of 173%). However, such grass cutting tasks are dangerous owing to the unstable positioning of workers. For robots to perform these grass cutting tasks, slipping and falling must be prevented on inclined surfaces. In this study, a robot based on stable propeller control and four-wheel steering was developed to provide stable locomotion during grass cutting tasks. The robot was evaluated in terms of locomotion for different steering methods, straight motion on steep slopes, climbing ability, and coverage area. The results revealed that the robot was capable of navigating uneven terrains with steep slope angles. Moreover, no slipping actions that could have affected the grass cutting operations were observed. We confirmed that the proposed robot is able to cover 99.95% and 98.45% of an area on a rubber and grass slope, respectively. Finally, the robot was tested on different slopes with different angles in hilly and mountainous areas. The developed robot was able to perform the grass cutting task as expected.
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Lee, Jong-Sen, Thomas L. Ainsworth e Yanting Wang. "Polarization Orientation Angle and Polarimetric SAR Scattering Characteristics of Steep Terrain". IEEE Transactions on Geoscience and Remote Sensing 56, n. 12 (dicembre 2018): 7272–81. http://dx.doi.org/10.1109/tgrs.2018.2849931.
Testo completo
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Sujantoko, Haryo Dwito Armono, Eko Budi Djatmiko e Risandi Dwirama Putra. "Stability Analysis of Concrete Block Anchor on Steep-Slope Floating Breakwater". Fluids 7, n. 8 (29 luglio 2022): 259. http://dx.doi.org/10.3390/fluids7080259.
Testo completoAbstract (sommario):
The floating breakwater is a protective structure that can absorb waves and can be used effectively in coastal areas with moderate wave environmental conditions. The stability of the floating breakwater is affected by the tension of the mooring line and the weight of the anchor. This research was conducted experimentally with a model scale of 1:10 on a floating breakwater with mooring systems and concrete anchor blocks with three types of configurations. The experiment was carried out on irregular waves with the following variations: wave height and period, mooring angle, structure width, and anchor weight. The results of this study indicate that at a wave steepness of 0.02–0.025 floating breakwater, which is installed with a mooring angle of 45 deg, configuration 3 has the largest stability parameter among other configurations. However, if the structure is installed at a mooring angle of 90 deg and cross, configurations 2 and 3 have almost the same stability. The test results also show that the relative width will affect the stability parameters. Configuration 3 (B = 30 cm) has the largest stability-parameter value among other configurations (B = 10 cm and 20 cm).
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Rumble, Stephen, Georg Schmitz e Stefanie Dencks. "Sonographic visibility of cannulas using convex ultrasound transducers". Biomedical Engineering / Biomedizinische Technik 64, n. 6 (18 dicembre 2019): 691–98. http://dx.doi.org/10.1515/bmt-2018-0174.
Testo completoAbstract (sommario):
Abstract The key for safe ultrasound (US)-guided punctures is a good visibility of the cannula. When using convex transducers for deep punctures, the incident angle between US beam and cannula varies along the cannula leading to a complex visibility pattern. Here, we present a method to systematically investigate the visibility throughout the US image. For this, different objective criteria were defined and applied to measurement series with varying puncture angles and depths of the cannula. It is shown that the visibility not only depends on the puncture angle but also on the location of the cannula in the US image when using convex transducers. In some image regions, an unexpected good visibility was observed even for steep puncture angles. The systematic evaluation of the cannula visibility is of fundamental interest to sensitise physicians to the handling of convex transducers and to evaluate new techniques for further improvement.
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Aghebatie, Behrouz, e Khosrow Hosseini. "Analyzing the turbulent flow on steep open channels". Water Supply 16, n. 5 (22 marzo 2016): 1207–13. http://dx.doi.org/10.2166/ws.2016.043.
Testo completoAbstract (sommario):
In channels with steep slopes, the flow is supercritical and the formation of roll waves is expected. In order to evaluate the flow behaviors in steep open channels, the Azad dam spillway is simulated numerically and its flow characteristics are compared with the physical model tests. In this study, the hydraulic variables including hydraulic depth and water surface profile are studied along the steep open channels. The k-ɛ turbulence model is considered in this study. It is shown that in the conditions in which the angle of the wave forehead is less than 35 degrees, the formation of roll waves is inevitable.
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Sheehan, Riley C., e Jinger S. Gottschall. "Walking Strategies Change With Distance From Hill Transition and Scale With Hill Angle". Journal of Applied Biomechanics 28, n. 6 (dicembre 2012): 738–45. http://dx.doi.org/10.1123/jab.28.6.738.
Testo completoAbstract (sommario):
Individuals must constantly modify their gait patterns to safely transition between different surfaces. The goal of the current study was to determine if gait changes could be detected two steps from a transition, and whether these changes scaled with the angle of the hill. We hypothesized that during the anticipation of uphill walking and the aftereffect of downhill walking, the magnitude of kinetic and electromyography changes would be greatest at steep hill angles and fewer steps from the transition. We collected force and electromy-ography data as participants walked on the level ground before an uphill ramp and after a downhill ramp. As hypothesized, there were significant main effects for both the number of steps and angle of the hill for the first vertical GRF peak, as well as lateral gastrocnemius and vastus lateralis activity. Overall, our results indicate that when transitioning to and from hills, anticipation and aftereffect responses occur at least two steps from the transition and are scaled to the angle of the hill.
29
Li, Xiao-Yan, Da-Bin Lin, Jia Ren, Shu-Jin Hou, Yu-Fei Li, Xiang-Gao Wang e En-Wei Liang. "Late Afterglow Bump/Plateau around the Jet Break: Signature of a Free-to-shocked Wind Environment in Gamma-Ray Burst". Astrophysical Journal 922, n. 1 (1 novembre 2021): 22. http://dx.doi.org/10.3847/1538-4357/ac1ff2.
Testo completoAbstract (sommario):
Abstract A number of gamma-ray bursts (GRBs) exhibit the simultaneous bumps in their optical and X-ray afterglows around the jet break. These bumps are similar to the afterglows of GRB 170817A, except preceded by a long shallow decay. Its origin is unclear. We suggest that these late simultaneous bumps may sound a transition of circumburst environment from a free-wind medium to a constant density medium, e.g., the shocked-wind medium. In this paper, we study the emission of an external-forward shock propagating in a free-to-shocked wind environment at different viewing angles. The late simultaneous bumps/plateaux followed by a steep decay are found in the optical and X-ray afterglows for high-viewing-angle observers. In addition, these theoretical bumps are preceded by a long plateau or shallow decay, which is formed during the external-forward shock propagating in the free-wind environment. For low-viewing-angle observers, the above bumps also appear but only in the situation where the structured jet has a low characteristic angle and the deceleration radius of the in-core jet flow is at around or beyond the free-wind boundary. We search GRBs for afterglows with the late simultaneous optical and X-ray bumps followed by a steep decay. GRBs 120326A, 100901A, 100814A, and 120404A are obtained. We find that an off-core (in-core) observed external-forward shock in a free-to-shocked wind environment can well explain the optical and X-ray afterglows in GRBs 120326A, 100901A, and 100814A (GRB 120404A).
30
Watanabe, Kunitaro, Joho Tokumine, Alan Kawarai Lefor, Akira Motoyasu, Kumi Moriyama e Tomoko Yorozu. "A Shallow Angle Short-Axis Out-of-Plane Approach Reduces the Rate of Posterior Wall Injuries in Central Venous Catheterization: A Simulation Study". BioMed Research International 2018 (10 settembre 2018): 1–5. http://dx.doi.org/10.1155/2018/4793174.
Testo completoAbstract (sommario):
The short-axis out-of-plane approach (SAX-OOP) is commonly used in ultrasound-guided internal jugular vein catheterization. However, this approach has a risk of posterior vein wall injuries. The authors hypothesized that a shallow angle of approach may reduce the rate of posterior wall injuries compared with the conventional steep angle approach. The present study aimed to evaluate whether a difference in the angle of approach of the needle affects the rate of posterior wall injuries. The present study was a randomized crossover-controlled trial involving 40 medical residents, conducted in the clinical training center at a hospital with a residency program. The primary outcome measure was the rate of posterior vessel wall injuries. Subjects received a didactic lecture during which the instructors taught three SAX-OOP techniques including the conventional free-hand method (procedure C), a needle navigation system (procedure N), and a shallow puncture angle using a guidance system (procedure S). Participants were trained in these approaches under supervision and each technique tested in a simulation environment. Thirty-four of 40 residents had no previous experience with central venous catheterization and were included in the final analysis. The rate of posterior vessel wall injuries in procedure S (9%) was significantly lower than using the other approaches (procedure C, 53%; procedure N, 41%). In conclusion, a shallow angle of approach using the SAX-OOP technique resulted in significantly fewer posterior vein wall injuries in central venous catheterization compared with steep angle techniques.
31
Heinemann, Patrick, e Dorina-Nicolina Isopescu. "Experimental and Numerical Case Studies about Two-Dimensional CHS Joints with a Symmetrical Y-Shape". Materials 15, n. 9 (28 aprile 2022): 3179. http://dx.doi.org/10.3390/ma15093179.
Testo completoAbstract (sommario):
Steel hollow section joints are mainly used for offshore structures, hall support or trusses. Current standards define different kinds of steel joints, but there are limitations regarding the geometry or load scenarios. Excluded joints are full-overlapped Y-joints with on-top connection. For these kinds of joints, there is no general design fundamental, so the design engineer has to build his/her own model. The aim of this paper is to figure out the resistance of this special undefined joint type and the influence of the inclination angle between the pipes. An experimental and numerical analysis of this joint was done. Due to this evaluation of the inclination angle, the design engineer could optimize the structure economically. Two different circular profile types were focused on. It was concluded that by increasing the inclination angle, the total applicable force decreased non-linearly. On one hand, the most economic design was achieved by choosing a steep angle. On the other hand, the resistance of the structure, regarding the maximum appliable force, could be increased. For the system in this paper, an increase up to 47% was achieved by choosing a profile with a thickness of 2.8 mm instead of 2.0 mm.
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Sade, Burak, e Joung H. Lee. "Significance of the tentorial alignment in approaching the trigeminal nerve and the ventral petrous region through the suboccipital retrosigmoid technique". Journal of Neurosurgery 107, n. 5 (novembre 2007): 932–36. http://dx.doi.org/10.3171/jns-07/11/0932.
Testo completoAbstract (sommario):
Object In this study, the authors aimed to identify the factors that would predict the operative distance between the trigeminal nerve (fifth cranial nerve) and the acousticofacial nerve complex (seventh–eighth cranial nerves) preoperatively when approaching the cerebellopontine angle (CPA) through the suboccipital retrosigmoid approach. Methods In 40 consecutive patients who underwent microvascular decompression of the trigeminal nerve via a sub-occipital retrosigmoid approach for trigeminal neuralgia, the following three parameters were assessed on preoperative magnetic resonance images: 1) the angle between the tentorium and the line drawn from the hard palate (tentorial angle); 2) the angle between the lines drawn along the petrous bones ventral to the internal auditory canals (petrous angle); and 3) the angle between the tentorium and the line connecting the opisthion to the inion (occipital angle). The distance between the trigeminal nerve and the acousticofacial nerve complex (referred to as “distance”) was measured intraoperatively. Statistical analysis was performed using the Pearson correlation test. Results The mean values were 50.9 ± 11.5° for the tentorial angle, 102.5 ± 13.1° for the petrous angle, 83.4 ± 9.7° for the occipital angle, and 3.1 ± 1.5 mm for distance. There was a strong inverse correlation between the tentorial angle and distance (r = −0.228, p = 0.08). The mean distance was 3.5 ± 1.9 mm for a tentorial angle less than 51° and 2.7 ± 1.1 mm for a tentorial angle of at least 51°. No correlation existed between either the petrous or occipital angles and distance. Conclusions The distance between the trigeminal nerve and acousticofacial nerve complex decreases in the presence of a steep tentorial angle. This limits the operating field between these cranial nerves when reaching the petroclival or the superior CPA regions through the retrosigmoid approach. Awareness of such anatomical features at the time of pre-operative planning is of paramount importance in selecting the optimum surgical approach and minimizing operative complications.
33
Spracklen, D. V., e R. Righelato. "Tropical montane forests are a larger than expected global carbon store". Biogeosciences 11, n. 10 (23 maggio 2014): 2741–54. http://dx.doi.org/10.5194/bg-11-2741-2014.
Testo completoAbstract (sommario):
Abstract. Tropical montane forests (TMFs) are recognized for the provision of hydrological services and the protection of biodiversity, but their role in carbon storage is not well understood. We synthesized published observations (n = 94) of above-ground biomass (AGB) from forest inventory plots in TMFs (defined here as forests between 23.5° N and 23.5° S with elevations ≥ 1000 m a.s.l.). We found that mean (median) AGB in TMFs is 271 (254) t per hectare of land surface. We demonstrate that AGB declines moderately with both elevation and slope angle but that TMFs store substantial amounts of biomass, both at high elevations (up to 3500 m) and on steep slopes (slope angles of up to 40°). We combined remotely sensed data sets of forest cover with high resolution data of elevation to show that 75% of the global planimetric (horizontal) area of TMF are on steep slopes (slope angles greater than 27°). We used our remote sensed data sets to demonstrate that this prevalence of steep slopes results in the global land surface area of TMF (1.22 million km2) being 40% greater than the planimetric area that is the usual basis for reporting global land surface areas and remotely sensed data. Our study suggests that TMFs are likely to be a greater store of carbon than previously thought, highlighting the need for conservation of the remaining montane forests.
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Spracklen, D. V., e R. Righelato. "Tropical montane forests are a larger than expected global carbon store". Biogeosciences Discussions 10, n. 12 (3 dicembre 2013): 18893–924. http://dx.doi.org/10.5194/bgd-10-18893-2013.
Testo completoAbstract (sommario):
Abstract. Tropical montane forests (TMFs) are recognised for the provision of hydrological services and the protection of biodiversity, but their role in carbon storage is not well understood. We synthesized published observations (n=89) of above-ground biomass (AGB) from forest inventory plots in TMFs (defined here as forests between 23.5° N and 23.5° S with elevations ≥ 1000 m a.s.l.). We found that mean (median) AGB in TMF is 257 (239) t per hectare of Earth's surface. We demonstrate that AGB declines moderately with both elevation and slope angle but that TMF store substantial amounts of biomass, both at high elevations (up to 3500 m) and on steep slopes (slope angles of up to 40°). We combined remote sensed datasets of forest cover with high resolution data of elevation to show that seventy five percent of the planimetric global area of TMF are on steep slopes (slope angles greater than 27°). We used our remote sensed datasets to demonstrate that this prevalence of steep slopes results in the global land-surface area of TMF (1.22 million km2) being 40% greater than the planimetric (horizontal) area that is the usual basis for reporting global land surface areas and remotely sensed data. Our study suggests that TMF are likely to be a greater store of carbon than previously thought, highlighting the need for conservation of remaining montane forests.
35
Kostaschuk, Ray A., e Jeremy G. Venditti. "Why do large, deep rivers have low-angle dune beds?" Geology 47, n. 10 (20 agosto 2019): 919–22. http://dx.doi.org/10.1130/g46460.1.
Testo completoAbstract (sommario):
Abstract Dunes are the most common bedform in sand-bedded rivers. Small, high-angle dunes (HADs) dominate in shallow (<2.5 m) flows and have lee sides with steep downstream-facing slipfaces (>24°) and reversed upslope-oriented flow in the separation vortex. In contrast, large, deep (>2.5 m) rivers have low-angle dunes (LADs) with gentle lee-side slipfaces (<24°; often <10°), little or no flow separation, and more-pronounced downslope currents. Avalanches driven primarily by particle interaction maintain slipfaces of HADs. On LADs, excess pore pressures that occur during the failure of thick, loosely packed deposits can produce liquefied avalanches that flow and stop on gentle gradients. As lee-side angles decrease over LADs, downslope currents increase in strength, accelerating avalanches, transporting bedload, and creating smaller, superimposed dunes and uniform concave slopes on the lee side. Nearly a century of research on dunes in shallow laboratory flows has assumed that dune morphodynamics are scale invariant, which is not true.
36
Sparks, W. B., J. Bailey, J. C. Hough, C. Brindle e D. J. Axon. "The Discovery of Blazar-Type Nuclei in Two Nearby Radio Ellipticals". Symposium - International Astronomical Union 127 (1987): 427–28. http://dx.doi.org/10.1017/s0074180900185572.
Testo completoAbstract (sommario):
Near infrared polarimetry of Centaurus A and IC5063 has revealed the existence of a steep spectrum highly polarized source in the nuclei of both galaxies. The position angle of polarization is perpendicular to the radio position angle. We interpret this polarized emission as synchrotron radiation. This, together with a luminosity of 5 × 1041erg s-1, suggests the galaxies are low luminosity blazars and that such nuclei may be common in elliptical galaxies.
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Guddati, Murthy N., e A. Homayoun Heidari. "Migration with arbitrarily wide-angle wave equations". GEOPHYSICS 70, n. 3 (maggio 2005): S61—S70. http://dx.doi.org/10.1190/1.1925747.
Testo completoAbstract (sommario):
We develop a new scalar migration technique that is highly accurate for imaging steep dips in heterogeneous media. This method is based on arbitrarily wide-angle wave equations (AWWEs) that are highly accurate space-domain one-way wave equations and have a form similar to the 15° equation. The accuracy of the proposed method is increased by introducing auxiliary variables, as well as adjusting the parameters of the approximation. Poststack migration is carried out by downward continuation using the AWWE, for which we have developed a stable, explicit, double-marching scheme. Up to 80° accuracy is achieved by second-order AWWE migration with only 2.3 times the computational effort of the 15° equation and requiring almost the same storage. We illustrate the performance of AWWE migration using impulse-response graphs, a single-dipping reflector, and a slice of the SEG/EAGE salt model.
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Kwon, Young-Hoo, Noelle J. Tuttle, Cheng-Ju Hung, Nicholas A. Levine e Seungho Baek. "Linear Relationships Among the Hand and Clubhead Motion Characteristics in Golf Driving in Skilled Male Golfers". Journal of Applied Biomechanics 37, n. 6 (1 dicembre 2021): 619–28. http://dx.doi.org/10.1123/jab.2021-0303.
Testo completoAbstract (sommario):
The purpose of this study was to investigate the linear relationships among the hand/clubhead motion characteristics in golf driving in skilled male golfers (n = 66; handicap ≤ 3). The hand motion plane (HMP) and functional swing plane (FSP) angles, the HMP–FSP angle gaps, the planarity characteristics of the off-plane motion of the clubhead, and the attack angles were computed from the drives captured by an optical motion capture system. The HMP angles were identified as the key variables, as the HMP and FSP angles were intercorrelated, but the plane angle gaps, the planarity bias, and the attack angles showed correlations to the HMP angles primarily. Three main swing pattern clusters were identified. The parallel HMP–FSP alignment pattern with a small direction gap was associated with neutral planarity and planar swing pattern. The inward alignment pattern with a large inward direction gap was characterized by flat planes, follow-through-centric planarity, spiral swing pattern, and inward/downward impact. The outward alignment pattern with a large outward direction gap was associated with steep planes, downswing-centric planarity, reverse spiral swing, and outward/upward impact. The findings suggest that practical drills targeting the hand motion pattern can be effective in holistically reprogramming the swing pattern.
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Gan, JianJun, e Y. X. Zhang. "Analysis of Model Tests of Rainfall-Induced Soil Deposit Landslide". Advances in Civil Engineering 2020 (22 luglio 2020): 1–13. http://dx.doi.org/10.1155/2020/6431247.
Testo completoAbstract (sommario):
A large number of deposit landslides are induced by rainfall, and those with different weak layers may be subject to catastrophic failure. This research investigates the rainfall infiltration effect on the stability of deposit landslides with a weak layer at different slope angles. Four rainfall physical model tests were conducted with fixed double penetration artificial rainfall technique and dynamic sensor technologies by using the rainfall test methods as modified in the paper. Deformation and mechanics parameters, as well as water content parameters in the key position in the deposit landslide, were monitored by means of various displacement monitoring sensors, dynamic soil pressure sensors, pore water pressure (PWP) monitoring sensors, and water content sensors. The results show that, under the same rainfall conditions, the rule of displacement and mechanical changes of deposit slope with different angles are similar, that the displacement, soil pressure, and PWP are characterized by two stages of rising and falling, and that the displacement of deposit slope with weak layer remains creep after rainfall. In addition, the displacement at the rear edge of the slope with a small angle is larger than that at the front of the steep slope, but the displacement in the front of the slope is opposite. Furthermore, the slope with a smaller angle is prone to form a tensile crack in the back of the slope, and its deformation and failure have the characteristics of a progressive and thrust-type landslide. While the failure in front of a steep slope (slope angle more than 60°) occurred first, the slope failure was characterized by sudden and retrogressive modes. The mathematical analysis of the model is also conducted which shows that deformation and failure can be divided into three stages, i.e., creep inoculation, accumulation uplift, and speed-up sliding. The test results can provide a reference for the investigation, design, and assessment of similar deposit slopes.
40
Pridmore, Peter A., e Peter H. Hoffmann. "The aerodynamic performance of the feathertail glider, Acrobates pygmaeus (Marsupialia: Acrobatidae)". Australian Journal of Zoology 62, n. 1 (2014): 80. http://dx.doi.org/10.1071/zo13071.
Testo completoAbstract (sommario):
Photographic and videographic investigations of the aerodynamic performance of four captive adult Acrobates pygmeus are described. During short (1–4 m) glides, steep angles of descent (>45°) and large angles of attack (up to 50°) were used mid-flight, and the possums failed to achieve steady velocities. During longer (>10 m) glides steady velocities of 5.3–7.5 m s–1 were achieved, and glide angles of 21–42° and angles of attack between 36° and 45° were used. The best (lowest) glide angles used at steady velocity were similar to those documented in sugar gliders, but involved lower air speeds. During steady gliding the forelimbs of Acrobates assumed an ‘elbows-out’ disposition similar to that of Petauroides volans, and unlike that of petaurid gliders. A glide polar for Acrobates shows that it uses lower air speeds and higher sinking speeds than other gliding animals for which polars are available (several birds and one bat). Few data on the radius of turn and sinking speed were obtained; nevertheless, in accord with theory, sinking speeds were higher during tighter turns. During flight the feather-like tail was used to generate pitching movements and adjust the angle of attack and hence glide angle. However, the control of turns seems to be achieved primarily through limb adjustments.
41
Zhang, Ying, Jiabing Zhang e Junhua Ma. "Stability Analysis of a Steep Rock Slope in a Large Open-Pit Mine in a High-Intensity Area: A Case Study of the Yejiagou Boron Iron Mine". Geofluids 2022 (18 agosto 2022): 1–14. http://dx.doi.org/10.1155/2022/9113173.
Testo completoAbstract (sommario):
The slope stability of open-pit mines has always been a major problem affecting the safe production of resources from open-pit step mines. At present, slope excavation in open-pit mines is difficult and slope instability problems are becoming increasingly prominent. In this study, an open-pit bench rock slope in Liaoning Province was taken as the research object. The physical parameters of the rock mass in the area were obtained through engineering drilling and large-scale direct shear tests. Based on the determination of the dominant group of the slope’s structural plane, the seepage deformation failure and maximum stress deformation of the slope were analyzed to explore the stability of high and steep rocky slopes in large open-pit mines. The results show that there is a group of dominant structural planes at the no. 1~3 observation points whose dip angle is steep and consistent with the slope inclination. The dip angle is slightly lesser at the slope toe, and the slope is basically a stable structure. The Janbu method was used to calculate the seepage stability of the slope and it is found that section 4-4 is in a dangerous area. In the stress nephogram, the maximum principal stress is located inside the slope, and the minimum principal stress is located at the surface of the free surface.
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Suda, Naoto, Sachiko Handa, Norihisa Higashihori, Takuya Ogawa, Michiko Tsuji e Kimie Ohyama. "Orthodontic Treatment of a Patient with Stickler Syndrome". Angle Orthodontist 77, n. 5 (1 settembre 2007): 931–39. http://dx.doi.org/10.2319/082406-347.
Testo completoAbstract (sommario):
Abstract Stickler syndrome (MIM 108300, 604841, 184840) is an autosomal dominant disease characterized by midfacial flattening and variable disorders of vision, hearing and articulation. There are three types of the syndrome caused by mutations in different genes (type 1, COL2A1; type 2, COL11A1; and type 3, COL11A2). About 20% of type 1 patients have cleft palate or bifid uvula, but there have been no case reports of orthodontic treatment of this syndrome so far. The Japanese female patient presented here with Stickler syndrome was characterized by a flat midface and had high myopia, sensorineural hearing loss, enlarged joints, and cleft of the soft palate. She had fairly small SNA and SNB angles and a steep mandibular plane with an enlarged gonial angle. The incisors of both arches were retroclined, and a large overjet and overbite were noted. Orthodontic treatment was initiated at 11 years of age using a lingual arch appliance followed by an edgewise multibracket appliance. Stable functional occlusion was obtained after the treatment. Most of the other seven Stickler syndrome patients exhibited pretreatment characteristics of small SNA and SNB angles, steep mandibular planes, enlarged gonial angles, and retroclined incisors of both arches, demonstrating the characteristic skeletal and occlusal features of this syndrome.
43
Zhu, Zhijie, Yin Hong e Zhuang Liang. "A Prediction Model for Top-Coal Drawing Capability in Steep Seams Based on PCA–GRNN". Geofluids 2022 (14 maggio 2022): 1–9. http://dx.doi.org/10.1155/2022/3590764.
Testo completoAbstract (sommario):
To improve prediction accuracy of top-coal drawing capability in steep seams, principal component analysis (PCA) and the general regression neural network (GRNN) are combined (PCA–GRNN model) to predict top-coal drawing capability in steep seams. Nine commonly used influencing factors are selected to establish a predictive index system for top-coal drawing capability in steep seams. The PCA is used to eliminate correlation and reduce dimensions of various indices, thus obtaining three linearly uncorrelated principal components (PCs) y 1 , y 2 , and y 3 , which form the input vectors of the GRNN. In this way, the factors that most affect the top-coal drawing capability in steep seams are found to be floor flatness, dip angle of the coal seam, and the hardness of the coal seam. The results show that the PCA–GRNN model outperforms the GRNN and random forest models in prediction results, which indicates that the PCA improves prediction accuracy of the GRNN model. It is feasible to predict top-coal drawing capability in steep seams by combining or even integrating different analytical models into one. The proposed PCA–GRNN model can be used to predict top-coal drawing capability in steep seams.
44
Yanagisawa, Shinya, Masashi Kimura, Keiichi Hagiwara, Atsuko Ogoshi, Tomotaka Yoneyama, Hiroaki Omae, Ryosuke Miyamoto e Hirotaka Chikuda. "A steep coronal graft bending angle is associated with bone tunnel enlargement of the posterolateral bundle after anterior cruciate ligament reconstruction". Journal of Orthopaedic Surgery 28, n. 1 (12 dicembre 2019): 230949901988881. http://dx.doi.org/10.1177/2309499019888811.
Testo completoAbstract (sommario):
Purpose: The correlation between the graft bending angle (GBA) of the anteromedial bundle and posterolateral bundle after anterior cruciate ligament reconstruction (ACLR) and postoperative tunnel enlargement was evaluated. Methods: Two hundred fifty-eight patients (137 males, 121 females; mean age 27.3 years) who had undergone double-bundle ACLR were included. Computed tomographic scans of the operated knee were obtained at 2 weeks and 6 months postoperatively. The area of the tunnel aperture for femoral anteromedial tunnel (FAMT) and femoral posterolateral tunnel (FPLT) was measured; the area at 2 weeks after ACLR was subtracted from the area at 6 months after ACLR and then divided by the area at 2 weeks after ACLR. The femoral tunnel angles were obtained with Cobb angle measurements. The femoral tunnel angle in the coronal plane was measured relative to the tibial plateau (coronal GBA). On the median value, the patients were divided into two groups in each of FAMT and FPLT; those with a coronal GBA of FAMT of ≥27° were classified as group A, while those with a coronal GBA of <27° were classified as group B, those with a coronal GBA of FPLT of ≥23° were classified as group C, while those with a coronal GBA of<23° were classified as group D. Results: Group A included 129 knees, while group B included 129 knees. Groups A and B did not significantly differ regarding FAMT enlargement. Group C included 133 knees, while group D included 125 knees. The percentage of FPLT enlargement in group C was significantly smaller than that in group D ( p = 0.001). Conclusions: A steep coronal GBA of the FPLT after ACLR results in greater FPLT enlargement. The present findings suggest that surgeons should avoid creating a steep GBA of the FPLT in the outside-in technique.
45
Luo, Xu, Xin Sha Fu, Li Xiong Gu e Lu Rong Cai. "Analysis of Effect of Fetching Girder from Trestle of Long-Span Steel Truss Bridge under Cantilever Erection". Applied Mechanics and Materials 587-589 (luglio 2014): 1522–26. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.1522.
Testo completoAbstract (sommario):
A large span steel truss bridge, it assembles "high, big, difficult, new, deep, steep, dangerous, heavy", etc., "eight" features in a body. In order to reduce the number of transportation ships and make the erection convenient, this paper studies a set of revolving beam erection scheme to improve the utilization efficiency of trestle. Through calculation, it is found that fetching girder directly from trestle is feasible. cantilever erection of the girder , The main truss linearis of the steel truss girder upstream and downstream has slightly deviation with the operating angle change of the cantilever crane and it need to stop lifting when monitoring and measuring, and the mast should be placed along the bridge direction.
46
Andelman, SM, J. Hedgecock, M. Solomito, R. Kostyun e JL Pace. "THE RELATIONSHIP BETWEEN PATELLAR MORPHOLOGY AND LATERAL PATELLAR INSTABILITY". Orthopaedic Journal of Sports Medicine 8, n. 4_suppl3 (1 aprile 2020): 2325967120S0025. http://dx.doi.org/10.1177/2325967120s00252.
Testo completoAbstract (sommario):
Background: Lateral patellar instability (LPI) is a substantial cause of morbidity in the pediatric population. Previously identified risk factors for LPI include trochlear dysplasia, a lateralized tibial tubercle, genu valgum, femoral anteversion, and external tibial torsion. Less is known regarding the relationship between patellar morphology and LPI. Purpose: The goal of this study is to determine whether there exists a relationship between patellar morphology and LPI. Methods: Magnetic resonance imaging (MRI) evaluation was performed for patients under 18 years of age with LPI and compared to a control group of MRIs of patients with anterior cruciate ligament (ACL) rupture. Using T2 axial MRI images, the lateral and medial facet angle of both the bone and cartilage of the patella was measured at three locations: the most proximal and distal aspects of the patella where the cartilage of the facets could be identified and the widest point of the patella. The width of the patella at each point was also recorded, resulting in 15 total data points per subject (5 at each of the three locations on the patella). Results were analyzed and compared between the instability group and the control group to determine any relationship between facet angle and LPI. Results: 196 MRIs were reviewed, 97 in the instability group and 96 in the control group. The LPI group was noted to have a less steep angle at the proximal medial patellar facet of both the bone (LPI 27.2° ± 9.3° ; control 32.7° ± 8.8°, p < 0.001) and cartilage (LPI 26.5° ± 8.8°, control 32.7° ± 8.4°, p < 0.001) as well as a less steep angle of the cartilage at the distal lateral facet (LPI 23.4° ± 7.2°, control 25.6° ± 6.6°, p = 0.033). No other differences were noted for the remaining 12 data points. Conclusion: The are very few differences in patellar morphology between patients with and without LPI. Patients were LPI have a less steep angle of the bone of the proximal medial facet, the cartilage of the proximal medial facet, and the cartilage of the distal lateral facet when compared to a control group. [Figure: see text]
47
Milledge, David G., Alexander L. Densmore, Dino Bellugi, Nick J. Rosser, Jack Watt, Gen Li e Katie J. Oven. "Simple rules to minimise exposure to coseismic landslide hazard". Natural Hazards and Earth System Sciences 19, n. 4 (17 aprile 2019): 837–56. http://dx.doi.org/10.5194/nhess-19-837-2019.
Testo completoAbstract (sommario):
Abstract. Landslides constitute a hazard to life and infrastructure and their risk is mitigated primarily by reducing exposure. This requires information on landslide hazard on a scale that can enable informed decisions. Such information is often unavailable to, or not easily interpreted by, those who might need it most (e.g. householders, local governments and non-governmental organisations). To address this shortcoming, we develop simple rules to minimise exposure to coseismic landslide hazard that are understandable, communicable and memorable, and that require no prior knowledge, skills or equipment to apply. We examine rules based on two common metrics of landslide hazard, (1) local slope and (2) upslope contributing area as a proxy for hillslope location relative to rivers or ridge crests. In addition, we introduce and test two new metrics: the maximum angle to the skyline and the hazard area, defined as the upslope area with slope >40∘ from which landslide debris can reach a location without passing over a slope of <10∘. We then test the skill with which each metric can identify landslide hazard – defined as the probability of being hit by a landslide – using inventories of landslides triggered by six earthquakes that occurred between 1993 and 2015. We find that the maximum skyline angle and hazard area provide the most skilful predictions, and these results form the basis for two simple rules: “minimise your maximum angle to the skyline” and “avoid steep (>10∘) channels with many steep (>40∘) areas that are upslope”. Because local slope alone is also a skilful predictor of landslide hazard, we can formulate a third rule as “minimise the angle of the slope under your feet, especially on steep hillsides, but not at the expense of increasing skyline angle or hazard area”. In contrast, the upslope contributing area has a weaker and more complex relationship to hazard than the other predictors. Our simple rules complement but do not replace detailed site-specific investigation: they can be used for initial estimations of landslide hazard or to guide decision-making in the absence of any other information.
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Full, R. J., e A. Tullis. "Energetics of ascent: insects on inclines". Journal of Experimental Biology 149, n. 1 (1 marzo 1990): 307–17. http://dx.doi.org/10.1242/jeb.149.1.307.
Testo completoAbstract (sommario):
Small animals use more metabolic energy per unit mass than large animals to run on a level surface. If the cost to lift one gram of mass one vertical meter is constant, small animals should require proportionally smaller increases in metabolic cost to run uphill. To test this hypothesis on very small animals possessing an exceptional capacity for ascending steep gradients, we measured the metabolic cost of locomotion in the cockroach, Periplaneta americana, running at angles of 0, 45 and 90 degrees to the horizontal. Resting oxygen consumption (VO2rest) was not affected by incline angle. Steady-state oxygen consumption (VO2ss) increased linearly with speed at all angles of ascent. The minimum cost of locomotion (the slope of the VO2ss versus speed function) increased with increasing angle of ascent. The minimum cost of locomotion on 45 and 90 degrees inclines was two and three times greater, respectively, than the cost during horizontal running. The cockroach's metabolic cost of ascent greatly exceeds that predicted from the hypothesis of a constant efficiency for vertical work. Variations in stride frequency and contact time cannot account for the high metabolic cost, because they were independent of incline angle. An increase in the metabolic cost or amount of force production may best explain the increase in metabolic cost. Small animals, such as P. americana, can easily scale vertical surfaces, but the energetic cost is considerable.
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Li, Panpan, Yuanyuan Tu, Xiang Chen, Yu Song e Huaijin Guan. "Clinical Outcomes of Steep-Axis One-Handed Phacoemulsification under the Guidance of a Verion Image-Guided System". Journal of Ophthalmology 2019 (15 settembre 2019): 1–7. http://dx.doi.org/10.1155/2019/7182324.
Testo completoAbstract (sommario):
Purpose. To compare the efficiency and safety of steep-axis one-handed phacoemulsification with steep-axis two-handed phacoemulsification.Patients and Methods. Patients with cataracts underwent steep-axis one-handed (steep-axis one-handed group) or steep-axis two-handed (steep-axis two-handed group) phacoemulsification with a 2.4 mm clear corneal incision (CCI) under the guidance of the Verion Image-Guided System. Intraoperative phacoparameters, such as visual acuity, surgically induced astigmatism (SIA), total corneal astigmatism (TCA), angle of error (AE), corneal volume (CV), and corneal endothelial cells, were compared.Results. There were no significant differences in the intraoperative phacoparameters between the two groups. The visual outcomes were significantly better in the steep-axis one-handed group than in the two-handed group at 1 week postoperatively (allp<0.05) but not at 1 month and 3 months postoperatively. TCAs were significantly decreased in both groups at 1 and 3 months postoperatively (allp<0.05). There were no significant differences at any follow-up points in both groups (allp<0.001). At 3 months postoperatively, the SIA was 0.95 ± 0.44 D in the steep-axis one-handed group and 1.01 ± 0.50 D in the steep-axis two-handed group; there was no significant difference between the groups. The AE was 39.45 ± 26.53° in the steep-axis one-handed group and 49.75° ± 26.23° in the steep-axis two-handed group, which were significantly different (p=0.005). Endothelial cell loss was significantly lower in the steep-axis one-handed group than that in the steep-axis two-handed group at all follow-up points (allp<0.05).Conclusions. Both the steep-axis one-handed and the steep-axis two-handed techniques could significantly decrease TCA. Compared with the steep-axis two-handed technique, the steep-axis one-handed technique has the advantage of decreasing the AE and reducing trauma to the cornea in soft-to-moderate nuclei.
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Chen, Yun Fu. "Influence of Surface Wettability on Dropwise Condensation Heat Transfer". Advanced Materials Research 228-229 (aprile 2011): 869–73. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.869.
Testo completoAbstract (sommario):
For finding influence of the surface wettability on dropwise condensation heat transfer, a model for dropwise condensation heat transfer has been established based on the drop size distributions and the heat transfer rate through a single drop with considering influence of contact angle to heat transfer. It has been shown based on the proposed model that up to a drop radius of 5μm, the rate of decrease in the drop population density is not as steep as the rate for a drop radius greater than 10μm, because coalescence between drops starts taking place. Varying the contact angle changes the drop distribution; higher the contact angle, lower the departing droplet size and large number density of small droplets. Heat flux first increases and then decreases with increasing contact angle under the temperature difference condition.