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Na, SeonHong, i Sang Inn Woo. "Theoretical Evaluation for Soil Thrust of Single-Track System over Clay Slope via Upper Bound Analysis". Applied Sciences 13, nr 9 (22.04.2023): 5222. http://dx.doi.org/10.3390/app13095222.
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This study aimed to theoretically evaluate soil thrust on a clay slope as a reaction force associated with the motion of an off-road tracked vehicle. The existing concept of the potential failure modes of a clay block on flat ground has extended to determine the soil thrust of sloped clay ground. Based on the upper-bound limit analysis, the soil thrust under the most critical failure was derived for three potential failure modes: block, triangular-wedge, and trapezoidal-wedge failures. Specifically, the influence of the slope angle, the shear strength of clay, the weight of a vehicle, and the geometry of a track system on the soil thrust was investigated. Only the block and triangular wedge failure modes were able to occur, and the geometry of a single-track system could lead to different failure modes. Under the block failure mode, the soil thrust decreased as the slope became stiff, and the vehicle weight increased. On the other hand, the soil thrust decreased as the slope angle decreased under the triangular-wedge failure mode.
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de Paula, Emygdio J. L., Alvaro Baik Cho, Rames Mattar Junior i Arnaldo V. Zumiotti. "Madelung’s Deformity: Treatment With Radial Osteotomy and Insertion of a Trapezoidal Wedge". Journal of Hand Surgery 31, nr 7 (wrzesień 2006): 1206–13. http://dx.doi.org/10.1016/j.jhsa.2006.06.017.
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Lu, Xi Lin, i Feng Di Li. "Study on the Stability of Large Cross-River Shield Tunnel Face with Seepage". Applied Mechanics and Materials 405-408 (wrzesień 2013): 1371–74. http://dx.doi.org/10.4028/www.scientific.net/amm.405-408.1371.
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By 3D numerical analysis, the seepage force on the tunnel face was obtained and shows linearly increasing trend with the water level. By considering the average seepage force on the wedge boundary of 3D trapezoidal wedge model, the limit support pressure to keep stability of tunnel face under seepage condition was obtained. The total limit support pressure increases almost linearly with the water level. In order to consider the deformation seepage coupling effect, the 3D coupled deformation and seepage numerical analysis was further used to investigate the influence of the water level on the failure of tunnel face, the results show the failure mode changes with the increase of water level, and the limit support pressure increases nonlinearly with the water level.
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Relvas, António T., i António N. Pinheiro. "Stepped chutes lined with wedge-shaped concrete blocks: hydrodynamic pressures on blocks and stability analysis". Canadian Journal of Civil Engineering 38, nr 3 (marzec 2011): 338–49. http://dx.doi.org/10.1139/l11-003.
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The use of wedge-shaped concrete block overlays to protect embankments subject to flows with relatively high velocities is an idea dating from the late 1960s. Subsequent studies addressed the block stability and design, with or without drainage layer underneath, and the flow characteristics. One aspect still lacking systematic research is the block stability considering the influence of the drainage layer and of the uplift pressure beneath the blocks. The stability of blocks located in the training walls of a trapezoidal cross section has never been investigated, although this type of section is expected when installing a concrete block overlay over embankments. The present study addresses this aspect, using a relatively large facility where the blocks are laid on a drainage layer over an embankment artificially saturated, thus intending to simulate a concrete block spillway installed over a compacted homogeneous earth dam. Data collected both in a trapezoidal flume and in a rectangular flume are is analyzed, together with other authors’ data for this type of stepped overlay. The inherent hydrodynamic stability is verified. Experiments with hydraulic jump formation over the blocks at the end of the flume also showed block stability.
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Wang, Ai Qin, Jing Pei Xie, Wen Yan Wang i Ji Wen Li. "The Numerical Simulation of Microstress for Hypereutectic Al-Si Alloys". Advanced Materials Research 211-212 (luty 2011): 1133–36. http://dx.doi.org/10.4028/www.scientific.net/amr.211-212.1133.
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The elastic-plastic finite element mechanical model of hypereutectic Al-Si alloy was established based on ANSYS software. When the Si particles were circle, trapezium, rectangle or triangle, the microstress of Al-Si alloy under the external load were simulated. When the size of Si particles changed from 25μm to 45μm, the stress of Si particles and matrix interface was calculated. The effects of morphology and size of Si particles and loads on micro-mechanics characteristic of alloy were analyzed. The results showed that: under the same load, triangle or wedge angle Si particles make the biggest stress in the matrix, trapezoidal particles make the second and the spherical particles make the smallest. With the increase of the load, the stress and the stress concentration of Si particles in the matrix was increased, the stress of wedge angle particle increases remarkably, but the stress of spherical particles increases slowly. With the increase of the size of Si particles, the stress and the stress concentration of Si particles in matrix are increased.
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Kampa, R., A. Al-Beer i T. Axelrod. "Madelung’s Deformity: Radial Opening Wedge Osteotomy and Modified Darrach Procedure Using the Ulnar Head as Trapezoidal Bone Graft". Journal of Hand Surgery (European Volume) 35, nr 9 (listopad 2010): 708–14. http://dx.doi.org/10.1177/1753193410375778.
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Surgery may be indicated in treating Madelung’s deformity and numerous techniques have been described. This study reports the early clinical and radiological results of a radial biplanar opening wedge osteotomy and modified Darrach procedure, using the excised ulnar head as a trapezoidal bone graft. Between 2000 and 2008, five adult wrists with symptomatic Madelung’s deformity underwent surgery. All patients were female, with an average age at surgery of 34 years. Assessment included range of movement, grip strength, DASH scores and radiological imaging. All patients improved both subjectively and objectively with regards to pain, functional range of movement, and appearance at mean follow-up of 55 months (range 14—113). All osteotomies united. One patient required removal of hardware for restricted rotation. This technique provided satisfactory results that are comparable to other studies, and avoids the use of iliac crest bone graft.
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Vanishree, B. Rao, i R. Manjula. "Analysis of various parameters affecting weir design and fabrication of Weirs: An Overview". MATEC Web of Conferences 144 (2018): 01006. http://dx.doi.org/10.1051/matecconf/201814401006.
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Several geometric parameters influence weir discharge and it is explained in our present study. The PK weir is more efficient than rectangular labyrinth weir due to reduction in entrance losses of PK weir inlet key geometry. PK weir is a type of labyrinth weir with variation in angle. Therefore, in this paper we also discuss about labyrinth weir. PKW are compatible for constructing on existing or new spillway with lesser space requirement and structural stability. PKW are installed in order to increase the discharge capacity for a given footprint area. PKW is used to increase the overflow capacity of existing dams such as, Hazelmare dam (South Africa), Dartmouth dam (Australia). Trapezoidal piano key weirs have higher discharge efficiency than rectangular weirs and it is due to interference wedge. Cd of TPKW is influenced by L/W but Wi/Wo has least effect.
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Li, Zhixiong, Tran Dinh Manh, M. Barzegar Gerdroodbary, Nguyen Dang Nam, R. Moradi i Houman Babazadeh. "The influence of the wedge shock generator on the vortex structure within the trapezoidal cavity at supersonic flow". Aerospace Science and Technology 98 (marzec 2020): 105695. http://dx.doi.org/10.1016/j.ast.2020.105695.
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Tananykhin, Dmitry, Maxim Grigorev, Elena Simonova, Maxim Korolev, Ilya Stecyuk i Linar Farrakhov. "Effect of Wire Design (Profile) on Sand Retention Parameters of Wire-Wrapped Screens for Conventional Production: Prepack Sand Retention Testing Results". Energies 16, nr 5 (3.03.2023): 2438. http://dx.doi.org/10.3390/en16052438.
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There are many technologies to implement sand control in sand-prone wells, drilled in either weakly or nonconsolidated sandstones. Technologies that are used to prevent sanding can be divided into the following groups: screens (wire-wrapped screens, slotted liners, premium screens, and mesh screens), gravel packs, chemical consolidation, and technological ways (oriented perforation and bottomhole pressure limitation) of sanding prevention. Each particular technology in these groups has their own design and construction features. Today, slotted liners are the most well-studied technology in terms of design, however, this type of sand control screen is not always accessible, and some companies tend towards using wire-wrapped screens over slotted liners. This paper aims to study the design criteria of wire-wrapped screens and provides new data regarding the way in which wire design affects the sanding process. Wires with triangular (wedge), trapezoidal, and drop-shaped profiles were tested using prepack sand retention test methodology to measure the possible impact of wire profile on sand retention capabilities and other parameters of the sand control screen. It was concluded that a trapezoidal profile of wire has shown the best result both in terms of sand production (small amount of suspended particles in the effluent) and in particle size distribution in the effluent, that is, they are the smallest compared to other wire profiles. As for retained permeability, in the current series of experiments, high sand retention did not affect retained permeability, although it can be speculated that this is mostly due to the relatively high particle size distribution of the reservoir.
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Patraev, E. V., M. S. Vakulin, Y. I. Gordeev i V. B. Yasinsky. "High-Speed Micromilling of Composite and Aluminum Alloy Parts". Proceedings of Higher Educational Institutions. Маchine Building, nr 12 (741) (grudzień 2021): 62–72. http://dx.doi.org/10.18698/0536-1044-2021-12-62-72.
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The paper deals with the design of the cutting part of complex-profile cutters with high productivity and surface quality. Numerical experiments carried out using the finite element method made it possible to determine the stresses and strains in the layer of the cut material when machining with multifaceted milling cutters of a new type and indirectly estimate the specific cutting forces. The required dimensions and shape of the cutting wedge are set with account for various geometric parameters of the cutting part, properties of the workpiece material, and cutting conditions. This made it possible to obtain a three-dimensional model of an end mill with a trapezoidal tooth and 700 cutting edges. Experimental studies also showed a change in the morphology of chips with a size of about 2 microns, which is in good agreement with the results of preliminary estimates by the finite element method. The productivity of processing with milling cutters of a new design can be improved by increasing the number of single cutting cycles up to4000–6000 s–1.
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Kravets, Viktor, Bogdan Sagalo i Azar Shukurov. "SPATIO-TEMPORAL PARAMETERS OF THE FRONT OF THE FORCE FIELD IN THE SYSTEM OF ELONGATED CHARGES". Geoengineering, nr 7 (5.12.2022): 30–37. http://dx.doi.org/10.20535/2707-2096.7.2022.267593.
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Purpose and task is to study the nature of the formation of the force field in the heel region by the interaction of the upper end parts of adjacent charges.Research results. Based on the fact that outside the zone of plastic deformations the force field is created by stresses close to elastic, analytical studies used a simplified computing apparatus based on known data on the shape and numerical values of force and time parameters of a single pulse from a single cylindrical charge of a given mass and length. The main results. The regularities of the formation of the force field in the boundary zones of action of the system of adjacent elongated charges are considered. The phenomenon of field degradation observed near the end part of the charges, which has a negative effect on the overall mechanical effect of the mass explosion, is analyzed.Conclusions and practical consequences. The shape of the total field of maximum stresses on the middle axis between adjacent charges initiated simultaneously from the lower end should have manifestations of the cumulative effect in the area of the upper end areas of adjacent charges.Therefore, after the inclined counter power fronts, counter mass shifts should take place, generally directed towards the superbore layer of the rock mass at the level of the stamping. The technique of forming upward movements in the intercharging volume of the rock is a new technological element that takes over the experience of conducting mass blasting operations according to an effective traditional system of switching a network of wells in the form of a horizontal wedge or trapezoidal cut. Such a traditional scheme initiates successive pairwise counter mass shifts with short decelerations in the direction of the lateral slope of the ledge. In contrast to this scheme, the new technology of mass explosion is based on a combined technique of simultaneous lower charge initiation in groups of 2-3 rows and the use of traditional short decelerations between groups to prevent excessive seismic effect. Thus, in groups the combined scheme of KSP "vertical wedge" which promotes additional destruction of the top layer of the planted rock block and reduction of an exit ofoversized fraction at the level of a stamping is realized.Keywords: charges, cumulative effect, rock mass, intercharging volume, explosion, seismic effect, vertical wedge.
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Sakhare, Akshay, Hafsa Farooq, Sanjay Nimbalkar i Goudappa R. Dodagoudar. "Dynamic Behavior of the Transition Zone of an Integral Abutment Bridge". Sustainability 14, nr 7 (30.03.2022): 4118. http://dx.doi.org/10.3390/su14074118.
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Weaker sections of a railway track, such as the approach sections, are prone to differential settlement under the action of repeated train loads. The railway tracks degrade more quickly at a critical section adjacent to a traditional rail bridge because of progressive deterioration. Opting for an integral abutment instead of a traditional bridge is gaining importance due to its improved performance in terms of track stiffness and reduced settlement. It is essential to understand such issues with the appropriate methodologies. This study investigates the behavior of an integral abutment bridge with the transition zone subjected to train loading. Generally, the transition zone is a two-part wedge section consisting of unbound granular material and cement bound mixture. A field monitored traditional abutment bridge system is used to validate the developed two-dimensional Finite Element (FE) model. The model is further developed to simulate the dynamic behavior of the transition zone against the varying speeds of the train. The parametric study is performed on the transition zone by varying its geometric configurations and considering different materials for the backfill. The results indicate that the trapezoidal approach slab influences the track displacement significantly. The transition zone thickness and material properties of the backfill have a greater effect on the overall track response. Based on the results, the stable transition zones are identified to cater to the gradual stiffness variation during train–track interaction.
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Kolomiiets, Oleksandra. "Constructive Solution of the Roof in Byzantine Temples of the Middle and Late Byzantine Periods". Ethnic History of European Nations, nr 66 (2022): 94–99. http://dx.doi.org/10.17721/2518-1270.2022.66.11.
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In this article, based on archaeological and hagiographic sources, the features of constructive solutions (techniques of construction and use of building materials) in the temples of the capital and provincial architectural schools of the middle and late Byzantine period were studied. The author focuses on the two main types of roofs of Byzantine temples – tiles and metal plates, the technology of their construction, roof shapes, the use of certain types of building materials and the specifics of using certain types of roofs in different regions of the Byzantine Empire. Each case of application of a certain technique / building material / type of roof is illustrated by the example of archeological finds or preserved mentions in the hagiographic literature. The study found that the most common version of the roof was ceramic tile, due to the cheapness of the material. A popular type for Byzantine roofs was a tile of weakly conical semi-cylindrical, sometimes flattened, shape; trapezoidal tile provided in the design of a wedge-shaped gutter for water drainage on the outside of the tile. It was found that the process of «assembling» the roof took place by connecting the tiles from the top elements (semi-cylindrical shape with a tooth-shaped end), which were driven between the already connected two tiles. During a study of the manufacture of ceramic tiles, it was found that the process was probably similar to the production of plinths (bricks) in the same kilns; instead, the main difference was that at the time of formation, trapezoidal, flat thin frames were used (so that the tile was formed on one side wider and narrower on the other – to overlap each other), and in the drying process these frames with clay were not placed on sand, and on a wooden board. The author also considered other variations of the tile – depending on the building material and shape. Thus, it was found that the material of the tile could not be limited to ceramics: in areas of construction, where there were no resources for the manufacture of ceramic tiles, stone was made and used. The most expensive and strongest variant of a material for a tile – metal – was chosen also because it was easy in processing. Particular emphasis in the study was placed on the use of metal plates for the roof. So the most popular material for this was lead – it melted at low temperatures, easily rolled into sheets (usually rectangular, but there were exceptions). The technique of construction of a roof with lead plates was that when superimposing plates, one overlapped another, for this purpose in places of seams they were bent and rolled. Lead for Byzantine construction was found to have been mined in several regions, including the northern Balkans, Pontus, and Macedonia. It is also noted that the use of lead plates for the roof contributed to the emergence and development of various forms of the roof (for example, the capital’s architectural school preferred a wavy surface).
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Bevan, Patrick J., Lutul D. Farrow, Jared Warren, Perry O. Hooper, Elisabeth Kroneberger i Jack T. Andrish. "Patient-Reported Outcomes After a Modified Albee Procedure". Orthopaedic Journal of Sports Medicine 9, nr 11 (1.11.2021): 232596712110281. http://dx.doi.org/10.1177/23259671211028167.
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Background: Trochlear dysplasia (TD) is a recognized condition that can become a risk factor for patellofemoral instability. A modified Albee osteotomy procedure using a trapezoidal-shaped wedge to elevate the lateral wall of the trochlea can be used with the goal of preventing further dislocation. However, outcomes studies are lacking, and scores on patient-reported outcome measures (PROMs) are largely unknown. Purpose/Hypothesis: The purpose of this study was to identify PROM scores for the Kujala Anterior Knee Pain Scale (AKPS), International Knee Documentation Committee (IKDC), Activity Rating System (ARS), and 100-point pain visual analog scale (VAS) for patients having undergone the modified Albee osteotomy. The hypothesis was that patients will have acceptable pain and function at mid- to long-term follow-up. Study Design: Case series; Level of evidence, 4. Methods: From 1999 to 2017, a total of 46 consecutive patients (49 knees) underwent a modified Albee procedure by a single surgeon at a single health care system. These 46 patients were contacted and asked to complete the AKPS, IKDC, ARS, and pain VAS. Additional demographic information was obtained via chart review. Frequencies and rates for categorical variables and means and standard deviations for continuous variables of the demographics and PROM scores were calculated. Results: PROM scores were obtained in 28 (30 knees; 61%) of the 46 patients. At minimum follow-up of 82 months, the mean scores were 78.5 ± 18.2 for AKPS, 61.2 ± 11.4 for IKDC, 5.2 ± 5.3 for ARS, and 24.4 ± 28.7 for VAS pain. Notably, only 1 of the 28 patients reported a patellofemoral dislocation since surgery, and this was an isolated incident without further instability. Conclusion: A modified Albee trochlear osteotomy can be a successful adjunctive procedure to prevent recurrent patellar dislocations in patients with mild TD. However, owing to the loss of one-third of patient follow-up scores and the absence of baseline function scores in this study, the procedure deserves further investigation as a way to address a particularly difficult dilemma for a select subset of patients with patellofemoral instability.
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BECHERT, D. W., M. BRUSE, W. HAGE, J. G. T. VAN DER HOEVEN i G. HOPPE. "Experiments on drag-reducing surfaces and their optimization with an adjustable geometry". Journal of Fluid Mechanics 338 (10.05.1997): 59–87. http://dx.doi.org/10.1017/s0022112096004673.
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Previous research has established that surfaces with tiny ribs (riblets) aligned in the streamwise direction can reduce the turbulent wall-shear stress below that of a smooth surface. Typical skin-friction reductions have been found to be about 5%. The results of the present investigation, however, demonstrate a considerable improvement over this value. This improvement is achieved by a systematic experimental optimization which has been guided by theoretical concepts.A key feature of our experiments is the utilization of an oil channel. Previous experiments in wind tunnels had to contend with very small riblet dimensions which typically had a lateral rib spacing of about 0.5 mm or less. By contrast, in our oil channel, the ribs can have a lateral spacing of between about 2 and 10 mm. This increased size of the surface structures enables test surfaces to be manufactured with conventional mechanical methods, and it also enables us to build test surfaces with adjustable geometry. In addition, the Berlin oil channel has a novel shear stress balance with an unprecedented accuracy of ±0.3%. This latter feature is a prerequisite for a systematic experimental optimization.In the present investigation, surfaces with longitudinal ribs and additional slits are studied. The experiments cover a fairly large range of parameters so that the drag reduction potential of a surface with ribs and/or slits is worked out conclusively. A large parameter range is made possible because of the adjustability of the surfaces as well as the automatic operation of the oil channel. In particular, the following tests were run:(i) Shear stress measurements with conventional riblet configurations, i.e. with triangular and semi-circular grooves, have been carried out. These measurements were necessary in order to establish the connection between our oil channel data and previous data from wind tunnels. As was previously established, we found a drag reduction of about 5%.(ii) An adjustable surface with longitudinal blade ribs and with slits was built and tested. Both groove depth and slit width could be varied separately and continuously during the experiment. It turned out, that slits in the surface did not contribute to the drag reduction. Nevertheless, these investigations show how perforated surfaces (e.g. for boundary-layer control) can be designed for minimal parasitic drag. On the other hand, with closed slits, an optimal groove depth for the rib surface could be determined, i.e. half of the lateral rib spacing. For this configuration, we found an 8.7% skin-friction reduction. By carefully eliminating deleterious effects (caused by little gaps, etc.), the skin-friction reduction could be improved to a record value of 9.9%.(iii) A quantitative comparison between theory and experiment was carried out. The theory is based on the assumption that riblets impede the fluctuating turbulent crossflow near the wall. In this way, momentum transfer and shear stress are reduced. The simplified theoretical model proposed by Luchini (1992) is supported by the present experiments.(iv) For technological applications of riblets, e.g. on long-range commercial aircraft, the above thin-blade ribs are not practical. Therefore, we have devised a surface that combines a significantly improved performance (8.2 %) with a geometry which exhibits better durability and enables previously developed manufacturing methods for plastic riblet film production to be used. Our riblet geometry exhibits trapezoidal grooves with wedge-like ribs. The flat floor of the trapezoidal grooves permits an undistorted visibility through the transparent riblet film which is essential for crack inspection on aircraft.
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Bai, Fuqiang, Zuowei Zhang, Yongchen Du, Fan Zhang i Zhijun Peng. "Effects of Injection Rate Profile on Combustion Process and Emissions in a Diesel Engine". Journal of Combustion 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/9702625.
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When multi-injection is implemented in diesel engine via high pressure common rail injection system, changed interval between injection pulses can induce variation of injection rate profile for sequential injection pulse, though other control parameters are the same. Variations of injection rate shape which influence the air-fuel mixing and combustion process will be important for designing injection strategy. In this research, CFD numerical simulations using KIVA-3V were conducted for examining the effects of injection rate shape on diesel combustion and emissions. After the model was validated by experimental results, five different shapes (including rectangle, slope, triangle, trapezoid, and wedge) of injection rate profiles were investigated. Modeling results demonstrate that injection rate shape can have obvious influence on heat release process and heat release traces which cause different combustion process and emissions. It is observed that the baseline, rectangle (flat), shape of injection rate can have better balance between NOx and soot emissions than the other investigated shapes. As wedge shape brings about the lowest NOx emissions due to retarded heat release, it produces the highest soot emissions among the five shapes. Trapezoid shape has the lowest soot emissions, while its NOx is not the highest one. The highest NOx emissions were produced by triangle shape due to higher peak injection rate.
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YONG, F. C., S. H. TAN, B. P. B. TOW i L. C. TEOH. "TRAPEZOID ROTATIONAL BONE GRAFT OSTEOTOMY FOR METACARPAL AND PHALANGEAL FRACTURE MALUNION". Journal of Hand Surgery (European Volume) 32, nr 3 (czerwiec 2007): 282–88. http://dx.doi.org/10.1016/j.jhsb.2007.01.005.
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Metacarpal and phalangeal fracture malunions with significant angulation deformity are associated with bone shortening, prominence of the metacarpal head in the palm or pseudoclaw deformity and may be symptomatic. If so, they may need corrective osteotomy procedures. Conventional methods of closing, or opening, wedge osteotomy do not restore the length of the bone exactly. Simultaneous correction of the angular deformity and restoration of bone length can be addressed by a trapezoid rotational bone graft osteotomy. A double osteotomy is done and the segment of bone is rotated and re-inserted as a bone graft. This was done successfully in four metacarpal and two phalangeal fracture malunions with angulation deformities.
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Song, Hong Wei, i Hai Tao Wang. "Analytical Approach for Face Stability Estimate of Tunnel with Pipe Roof Reinforcement". Advanced Materials Research 243-249 (maj 2011): 347–50. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.347.
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One of the most popular pre-reinforcement structures in the construction of tunnels through weak grounds would be the pipe roof reinforcement. This composite structure consists on installing, prior to the excavation of a length of tunnel, a series of pipes, either parallel to the tunnel axis or at a certain angle with it. By injecting grout through the pipes, the ground in between the pipes is stiffened and the pipes are connected, creating a kind of ‘umbrella’ above the area to be excavated. In this paper, by modifying the upper bound solution for tunnel face stability, the three-dimensional model for expressing the tunnel face stability with pipe roof reinforcement was established. For a typical example, the solutions computed by the proposed approach were compared with the results given by wedge model, trapezoid wedge model and centrifugal-model test to verify the reasonability of the method. It is shown that the calculation results of limit analysis are in close agreement with test results.
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ROPARS, M., P. SIRET, R. KAILA, F. MARIN, N. BELOT i T. DRÉANO. "Anatomical and Radiological Assessment of Trapezial Osteotomy for Trapezial Dysplasia in Early Trapeziometacarpal Joint Arthritis". Journal of Hand Surgery (European Volume) 34, nr 2 (12.03.2009): 264–67. http://dx.doi.org/10.1177/1753193408098905.
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Opening wedge osteotomy of the trapezial saddle was reported first by Kapandji and Heim (2002) as a possible surgical treatment for early trapeziometacarpal joint arthritis. This study evaluates the feasibility and anatomical risks of the procedure. Ten upper limbs from fresh cadavers were used for this anatomical and radiological study. A dorsolateral opening wedge osteotomy with a 10° correction was performed on each specimen. CT scans and AP radiographs of all the wrists were performed before and after osteotomy to assess the correction of the slope angle, defined as the angle between the longitudinal axis of the second metacarpal and the axis of the trapeziometacarpal articulation. On standard radiographs, mean trapezial slope was 126° preoperatively and 117° postoperatively. On sagittal and coronal CT reconstructions, one case of trapezial translation and two impingements between trapezoid and trapezium bones were identified. Trapezial osteotomy is technically demanding with several possible complications, but merits further study for young patients with Eaton stage 1 or 2 osteoarthritis and an abnormal trapezial slope.
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Morán, Rafael, i Miguel A. Toledo. "Design and construction of the Barriga Dam spillway through an improved wedge-shaped block technology". Canadian Journal of Civil Engineering 41, nr 10 (październik 2014): 924–27. http://dx.doi.org/10.1139/cjce-2014-0120.
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The Barriga Dam (Burgos, Spain) is a unique case study because its trapezoid spillway is located on the dam body and is composed of wedge-shaped concrete blocks (WSB) that include certain relevant improvements. This note summarizes the main features of the studies, the key aspects of the final design of the WSB and their placement on the dam, and important details of the spillway design. The design team concluded the study by showing the suitability of this enhanced technology for application to small dams and ponds in the short term, even with unit flows above 5 m2/s.
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Chambers, Spencer B., Clare E. Padmore, Stacy Fan, Ruby Grewal, James Johnson i Nina Suh. "The Impact of Scaphoid Malunion on Carpal Motion: An In-Vitro Analysis". Journal of Hand Surgery (Asian-Pacific Volume) 26, nr 03 (10.08.2021): 396–402. http://dx.doi.org/10.1142/s2424835521500387.
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Background: The clinical significance of scaphoid malunion is debated and its effect on wrist kinematics is poorly understood. Alterations to scaphoid morphology in other pathologies result in significant sequelae and arthrosis. By understanding the impact of scaphoid malunion on carpal kinematics, better insight can be garnered to inform models of wrist motion and clinical treatment of this injury. Methods: Seven cadaveric upper extremities underwent active wrist flexion and extension in a custom motion wrist simulator with scaphoid kinematics being captured with respect to the distal radius. A three-stage protocol of progressive simulated malunion severity was performed [intact, 10° malunion (Mal 10°), 20° malunion (Mal 20°)] with data analyzed from 45° wrist extension to 45° wrist flexion. Scaphoid malunions were modelled by creating successive volar wedge osteotomies and reducing the resultant scaphoid fragments with two 0.062” Kirshner wires. Motion of the scaphoid, lunate, trapezium-trapezoid was recorded using optical trackers. Results: Increasing scaphoid malunion severity did not significantly affect scaphoid or trapezium-trapezoid motion (p > 0.05); however, it did significantly alter lunate motion (p < 0.001). Increasing malunion severity resulted in progressive lunate extension across wrist motion (Intact – Mal 10°: mean difference (mean dif.) = 7.1° ± 1.6, p < 0.05; Intact – Mal 20°: mean dif. = 10.2° ± 2.0, p < 0.05). Conclusions: In this in-vitro model, increasing scaphoid malunion severity was associated with progressive extension of the lunate in all wrist positions. The clinical significance of this motion change is yet to be elucidated, but this model serves as a basis for understanding the kinematic consequences of scaphoid malunion deformities.
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Li, Jingrui, Jietuo Wang, Teng Liu, Jingjin Dong, Bo Liu, Chaohui Wu, Ying Ye, Hu Wang i Haifeng Liu. "An Investigation of the Influence of Gas Injection Rate Shape on High-Pressure Direct-Injection Natural Gas Marine Engines". Energies 12, nr 13 (4.07.2019): 2571. http://dx.doi.org/10.3390/en12132571.
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High-pressure direct-injection (HPDI) natural gas marine engines are widely used because of their higher thermal efficiency and lower emissions. The effects of different injection rate shapes on the combustion and emission characteristics were studied to explore the appropriate gas injection rate shapes for a low-speed HPDI natural gas marine engine. A single-cylinder model was established and the CFD model was validated against experimental data from the literature; then, the combustion and emission characteristics of five different injection rate shapes were analyzed. The results showed that the peak values of in-cylinder pressure and heat release rate profiles of the triangle shape were highest due to the highest maximum injection rate, which occurred in a phase close to the top dead center. The shorter combustion duration of the triangle shape led to higher indicated mean effective pressure (IMEP) and NOx emissions compared with other shapes. The higher initial injection rates of the rectangle and slope shapes had a negative effect on the ignition delay periods of pilot fuel, which resulted in lower in-cylinder temperature and NOx emissions. However, due to the lower in-cylinder temperature, the engine power output was also lower. Otherwise, soot, unburned hydrocarbon (UHC), and CO emissions and indicated specific fuel consumption (ISFC) increased for both rectangle and slope shapes. The trapezoid and wedge shapes achieved a good balance between fuel consumption and emissions.
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Lo, Der-Chang, Keh-Han Wang i Tai-Wen Hsu. "Two-Dimensional Free-Surface Flow Modeling for Wave-Structure Interactions and Induced Motions of Floating Bodies". Water 12, nr 2 (15.02.2020): 543. http://dx.doi.org/10.3390/w12020543.
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In this study, the level set (LS) and immersed boundary (IB) methods were integrated into a Navier–Stokes equation two-phase flow solver, to investigate wave-structure interactions and induced motions of floating bodies in two dimensions. The movement of an interfacial boundary of two fluids, even with severe free-surface deformation, is tracked by using the level set method, while an immersed object inside a fluid domain is treated by the IB method. Both approaches can be implemented by solving the Navier–Stokes equations for viscous laminar flows with embedded objects in fluids. For accurate treatment of the solid–liquid phase, appropriate source terms as forcing functions to take into account the hydrodynamic effects on the body boundaries are added into the governing equations. The integrated compact interfacial tracking techniques between the interfaces of gas–liquid phase and the solid–liquid phase allow the use of a combined Eulerian Cartesian and Lagrangian grid system. Problems related to the fluid-structure interactions and induced motions of a floating body, such as (a) a dam-break wave over a dry bed; (b) a dam-break wave over either a submerged semicircular or rectangular cylinder; (c) wave decomposition process over a trapezoid breakwater; (d) a free-falling wedge into a water body; and (e) wave packet interacting with a floating body are selected to test the model performance. For all cases, the computed results are found to agree reasonably well with published experimental data and numerical solutions. For the case of modeling wave decomposition process, improved solutions are obtained. The detailed features of flow phenomena described by the physical variables of velocity, pressure and vorticity are presented and discussed. The present two-phase flow model is proved to have the advantage of simulating the cases with induced severe interfacial oscillations and coupled gas (or air) motions where the single-phase model may miss the contributions of the air motions on the interfaces. Additionally, the proposed method with uses of the LS and IB methods is demonstrated to be able to achieve the reliable predictions of complex flow fields.
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Turner, Edward J., Matthew F. Bogdan, Tyler M. O’Connell, Wing F. Ng, Kevin T. Lowe, Loren Crook, Richard Stevenson i James Roberts. "Measurement Drift in 3-Hole Yaw Pressure Probes From 5µm Sand Fouling at 1050 °C". Journal of Turbomachinery 143, nr 3 (1.03.2021). http://dx.doi.org/10.1115/1.4050069.
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AbstractThe present paper focuses on the resilience of 3-hole pressure probes to hot sand fouling in turbomachinery environments. These probes are utilized inside jet engine hot sections for diagnostics and flow characterization. Ingestion of sand and other particulates pose a significant risk to hot section components and measurement devices in gas turbine engines. In this study, wedge, cylindrical, and trapezoidal probes were exposed to hot section turbine aerothermal conditions of 1050 °C and 65–70 m/s flow velocity and fouled with 0–5 µm Arizona Road Dust (ARD). Sand accumulated more rapidly on the surface of the trapezoidal and cylindrical probe geometries than on the surface of the wedge probe geometry. Probe calibrations following sand fouling were performed in an ambient temperature, open air, calibration jet at Mach 0.3 and 0.5. Calibration curves using nondimensional coefficients were used to assess probe error in yaw angle due to sand fouling. Probe error was based on each probe’s ability to accurately measure flow direction over a flow angle range of [−10 deg, 10 deg]. On average, the probes displayed greater error at Mach 0.5 than Mach 0.3. The wedge probe performed the best after sand fouling and displayed a maximum error of less than ±2 deg in yaw angle. In contrast, the cylindrical probe performed the worst after sand fouling and displayed maximum errors of more than ±8 deg in yaw angle. Transient response did not change notably with sand fouling.
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Mhaskar, Vikram A., i Rachit Saggar. "Trapezoidal Wedge Osteotomy with Ligament Reconstruction for Chronic Instability following Failed ACLR". Indian Journal of Orthopaedics, 18.07.2023. http://dx.doi.org/10.1007/s43465-023-00954-y.
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Bhat, Anil K., G. Mithun Pai, Ashwath M. Acharya i Amruth Manohar. "Wrist Arthrodesis Using a Trapezoidal Wedge Graft from the Distal Radius and a Low-Profile Reconstruction Plate". Indian Journal of Orthopaedics, 17.04.2023. http://dx.doi.org/10.1007/s43465-023-00884-9.
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Abstract Background Various intramedullary or dorsally based fusions have been utilised to perform wrist arthrodesis. Although the dorsal plate is rigid and well constructed, the standard of care was replenishing the arthrodesis site with an iliac crest bone graft. Due to the high morbidity of the donor site, alternatives such as distal radius bone grafts have gained popularity. In this study, wrist arthrodesis was performed with a locally accessible trapezoidal wedge graft from the distal radius and a low-profile reconstruction plate to evaluate the radiological and functional outcome. Methods We retrospectively reviewed 22 wrists, 14 brachial plexus injuries, 4 post-traumatic injuries, and 4 rheumatoid arthritis patients, with a mean follow-up of 31 months. Union was evaluated on radiography. The functional outcomes were evaluated using a visual analog scale incorporated into a questionnaire. Results All 22 fusions united successfully, with a mean duration of 12 weeks and a wrist position of an average 17.5 degrees of extension and 6 degrees of ulnar deviation. The aesthetics of the wrist showed the most significant change, and overall satisfaction levels increased. Conclusions A locally accessible cortico-cancellous graft from the dorsum of the radius is a reliable alternative to an iliac crest or carpal bone graft with high potential for the union. It also serves as a stable strut in our construct, allowing us to use a low-profile reconstruction plate. The Reconstruction (3.5 System) plate can be used safely with excellent results and a low implant prominence or breakage risk.
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Souza, Luciana Aparecida de, Samara de Paula Lopes, Yasmin Daoualibi, Ana Cristina Sbaraini Mósena, Vinícius Vasconcellos da Cruz Gonçalo, Cristiano Chaves Pessoa da Veiga, Bruno Ferreira Spíndola, Wanessa Pereira da Silva, Daniel Guimarães Ubiali i Saulo Andrade Caldas. "Segmental hypoplasia of the spinal cord and syringomyelia in a calf". Ciência Rural 50, nr 3 (2020). http://dx.doi.org/10.1590/0103-8478cr20190359.
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ABSTRACT: Congenital malformations are functional and structural changes in organ systems, tissues, or organs that may develop during the embryonic or fetal phase. Spinal cord malformations, such as segmental hypoplasia of the spinal cord (SHSC) and syringomyelia, are rare in bovines. A Girolando calf from Valença, Rio de Janeiro, was admitted to the Veterinary Hospital of Universidade Federal Rural do Rio de Janeiro because of motor incoordination. Clinical evaluation revealed a 5-cm depression area in the spine at the dorsal line of the thoracic region. Neurological examination revealed reduced proprioception, pelvic limb extension with increased nociceptive activity, and reduced anal reflex. In radiographic examination, the body of the T11 vertebra had a trapezoidal wedge shape with ventral hemivertebra, probable agenesis or hypoplasia of the T11-T12 spinous processes, and fusion of the T9-T10 spinous processes. Myelography revealed extradural spinal compression caused by vertebral malformations. Necropsy showed no spinous processes (T11-T12), cranial stenosis in the medullary canal (T11-T13), and 1-3-mm pores in the white matter of the thoracic spinal cord (T8-T11). Microscopy revealed cystic dilatations in the white matter (T9-T11), cystic areas of varying sizes (T8-T9), and moderate reduction in the gray matter around the central canal of the medulla (T11-T13). Here, we reported the clinical and pathological findings of SHSC and syringomyelia in a Girolando calf. The features should be differentiated from other spinal cord syndromes. Congenital malformations are of economic importance, and their etiology and diagnosis are fundamental to disease control and progenitor-selection programs.
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Madhavan, Srivatsan, Prashant Singh i Srinath Ekkad. "Effect of Rotation on Heat Transfer in AR = 2:1 and AR = 4:1 Channels Connected by a Series of Crossover Jets". Journal of Turbomachinery 144, nr 6 (24.02.2022). http://dx.doi.org/10.1115/1.4053237.
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Abstract Detailed heat transfer measurements using transient liquid crystal thermography were performed on a novel cooling design covering the mid-chord and trailing edge region of a typical gas turbine blade under stationary and rotating conditions. The test section comprised two channels with aspect ratio (AR) of 2:1 (mid-chord) and 4:1 (trailing edge), where the coolant was fed into the AR = 2:1 channel from the root. Rib turbulators with a pitch-to-rib height ratio (p/e) of 10 and rib height-to-channel hydraulic diameter ratio (e/Dh) of 0.075 were placed in the AR = 2:1 channel at an angle of 60 deg relative to the direction of flow. The coolant after entering this section was routed to the AR = 4:1 section through a set of crossover jets. The purpose of the crossover jets was to induce sideways impingement onto the pin fins that were placed in the 4:1 section to enhance heat transfer. The 4:1 section had a realistic trapezoidal shape that mimics the trailing edge of an actual gas turbine blade. The pin fins were arranged in a staggered array with a center-to-center spacing of 2.5 times the pin diameter in both spanwise and streamwise directions. The trailing edge section consisted of both radial and cutback exit holes for flow exit. Experiments were performed for the Reynolds number (Redh(AR=2:1)) of 20,000 at Rotation numbers (Rodh(AR=2:1)) of 0, 0.1, and 0.14. The channel-averaged heat transfer coefficient on trailing side was ∼28% (AR = 2:1) and ∼7.6% (AR = 4:1) higher than the leading side for Rotation number (Ro) of 0.1. It is shown that the combination of crossover jets and pin fins can be an effective method for cooling wedge-shaped trailing edge channels over axial cooling flow designs.
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Deng, Zhipeng, Bowen Hu, Xi Yang, Lei Wang i Yueming Song. "The improved bioactive n-HA/PA66 cage versus the PEEK cage in anterior cervical fusion: results from a 6-year follow-up and a case-matched study". BMC Musculoskeletal Disorders 23, nr 1 (21.12.2022). http://dx.doi.org/10.1186/s12891-022-06081-3.
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Abstract Background The nanohydroxyapatite/polyamide 66 (n-HA/PA66) cage, a bioactive nonmetal cage, is fabricated in a hollow cylindrical shape and has been widely used for decades with good clinical outcomes for anterior cervical fusion. However, there remain some radiological complications, such as a slightly high subsidence rate. To improve the clinical outcomes, the improved n-HA/PA66 cage now has been developed into a trapezoidal and wedge shape, a better biomechanical shape matching the cervical spine that is similar to that of the PEEK cage. However, there have been no long-term comparisons of the improved n-HA/PA66 cage and PEEK cage in anterior cervical reconstruction. Methods Fifty-eight patients who underwent single-level anterior cervical decompression and fusion (ACDF) with the improved n-HA/PA66 cage (n-HA/PA66 group) were matched with patients with the PEEK cage (PEEK group) by clinical presentation, segment, age and sex. All patients underwent a minimum of 6 years of follow-up. The radiographic parameters (cage subsidence, fusion status, cervical lordosis, and segmental sagittal alignment) and clinical parameters (10-point visual analogue scale, Neck Disability Index and Japanese Orthopedic Association scores) from patients were evaluated before surgery, immediately after surgery, and at the latest follow-up. Results The n-HA/PA66 and PEEK groups were well matched in terms of clinical presentation, segment, age, and sex at surgery. The n-HA/PA66 and PEEK cages had similar fusion rates at 6 months postoperatively (n-HA/PA66: 58.6% vs. PEEK: 51.7%, P = 0.455) and at the last follow-up (n-HA/PA66: 96.6% vs. PEEK: 93.1%, P = 0.402). The respective cage subsidence rates in the n-HA/PA66 and PEEK groups were 6.9 and 12.1% (P = 0.342). The correction of SA was similar between the groups at the final follow-up (n-HA/PA66: 4.29 ± 1.99 vs. PEEK: 3.99 ± 2.59 P = 0.464). There were no significant differences between the two groups in mean cervical lordosis, visual analogue scale scores of the neck and arm, NDI scores, JOA scores or patients’ overall satisfaction at the final follow-up. Conclusion After single-level ACDF, the improved n-HA/PA66 cage had similar excellent results in both radiological and clinical outcomes compared with the PEEK cage over 6 years of follow-up. According to these results, the improved n-HA/PA66 cage and the PEEK cage could be comparable for ACDF.