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Journal articles on the topic "Different cluster tip reduction (1/3"
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Zheng, Wei, Jesús García, Pedro Balda, and Fernando Martínez de Toda. "Effects of late winter pruning at different phenological stages on vine yield components and berry composition in La Rioja, North-central Spain." OENO One 51, no. 4 (2017): 363. http://dx.doi.org/10.20870/oeno-one.2017.51.4.1863.
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Aims: Under global warming, the desynchrony between technology maturity and phenolic maturity of wine grapes is a worthy concern. Late winter pruning (LWP) has been proved to be an effective way to delay the grape phenological stages. The aim of this study was to evaluate the effects of LWP at different phenological stages (based on Baillod & Baggiolini system) on the delay of the grape ripening, on vine yield components as well as on berry composition, among others, the anthocyanin to sugar ratio.Methods and results: The two-year (2015 and 2016) trial was conducted in Rioja wine region (North of Spain) on Maturana vines and in each year, four pruning treatments were carried out taking apical buds/shoots as reference: (1) winter pruning at stage A (WPA; dormant bud); (2) LWP at stage C (LWPC; green shoot tip) in 2015 and at stage F (LWPF; inflorescence clearly visible) in 2016; (3) LWP at stage G (LWPG; inflorescences separated); (4) LWP at stage H (LWPH; flowers separated). LWPC failed to delay the late phenological stages and did not exert important influence on vine yield and berry composition. LWPG and LWPH succeeded to delay all the phenological stages of grapes to a great extent and created a considerably cooler and longer ripening period compared to WPA. Vine yield was not affected by LWPF and was reduced significantly (averagely by 41%) by LWPG. LWPH lead to great losses in yield (averagely by 67%), especially in 2015. LWPG did not change the fruit composition while LWPH increased the ratio of anthocyanin to sugar and helped to maintain a relatively high level of acidity in berries.Conclusions: The primary cause of the decline in production seems to be the losses of flowers and/or the reduction in fruit set percentage in the current season, instead of the losses in inflorescences within buds in the previous season. For Maturana grapes, LWP after the stage F would reduce the vine yield and could be applied as an alternative to the time consuming cluster thinning to meet the needs of yield control. Delaying the winter pruning to stage H could improve the fruit quality in spite of the greater risk of botrytis and a serious decline in production.Significance and impact of the study: The outcomes of this research open a door for the winegrowers to realize the yield control in a simple way. Also, for those who only pursue wines of top quality (regardless of production), a very late winter pruning might provide them with high-quality grapes. Moreover, as can be seen obviously from our results, viticulturists could postpone the budburst date to whatever extent they wish thus reducing the risk of spring frost injury to zero, though this point is not our focus in the study.
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Ameri, A. A., E. Steinthorsson, and D. L. Rigby. "Effects of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficency in Axial Turbines." Journal of Turbomachinery 121, no. 4 (1999): 683–93. http://dx.doi.org/10.1115/1.2836720.
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Calculations were performed to assess the effect of the tip leakage flow on the rate of heat transfer to blade, blade tip, and casing. The effect on exit angle and efficiency was also examined. Passage geometries with and without casing recess were considered. The geometry and the flow conditions of the GE-E3 first-stage turbine, which represents a modern gas turbine blade, were used for the analysis. Clearance heights of 0, 1, 1.5, and 3 percent of the passage height were considered. For the two largest clearance heights considered, different recess depths were studied. There was an increase in the thermal load on all the heat transfer surfaces considered due to enlargement of the clearance gap. Introduction of recessed casing resulted in a drop in the rate of heat transfer on the pressure side, but the picture on the suction side was found to be more complex for the smaller tip clearance height considered. For the larger tip clearance height, the effect of casing recess was an orderly reduction in the suction side heat transfer as the casing recess height was increased. There was a marked reduction of heat load and peak values on the blade tip upon introduction of casing recess; however, only a small reduction was observed on the casing itself. It was reconfirmed that there is a linear relationship between the efficiency and the tip gap height. It was also observed that the recess casing has a small effect on the efficiency but can have a moderating effect on the flow underturning at smaller tip clearances.
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Tucker, V. A. "GLIDING BIRDS: REDUCTION OF INDUCED DRAG BY WING TIP SLOTS BETWEEN THE PRIMARY FEATHERS." Journal of Experimental Biology 180, no. 1 (1993): 285–310. http://dx.doi.org/10.1242/jeb.180.1.285.
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1. The feathers at the wing tips of most birds that soar over land separate both horizontally and vertically in flight to form slotted tips. The individual feathers in the slotted tips resemble the winglets used on the wing tips of some aircraft to reduce induced drag. 2. A wing that produces lift leaves a pair of vortex sheets in its wake. Wing theory shows that winglets can reduce the kinetic energy left in the vortex sheets, and hence the induced drag, by spreading vorticity both horizontally and vertically. 3. This paper describes the aerodynamic forces on a wing made of a base wing and different wing tips. The feathered wing tip was slotted and was made of four primary feathers from a Harris' hawk (Parabuteo unicinctus). The Clark Y tip was unslotted and was made of balsa wood shaped to a Clark Y aerofoil. The balsa feather tip was slotted and was made of three balsa wood wings shaped like feathers. 4. The base wing in a wind tunnel at an air speed of 12.6 m s-1 generated upwash angles as high as 15° at the end of the wing when the angle of attack of the wing was 10.5°. The feathered tip responded to upwash by increasing its lift to drag ratio (L/D) by 107 %, from 4.9 to 10.1, as the angle of attack of the base wing increased from 4° to 14°. The L/D values of the balsa feather tip and the Clark Y tip increased by 49 % and 5 %, respectively, for the same change in angle of attack. 5. With the angle of attack of the base wing fixed at 13°, changing the angle of attack of the wing tip changed the drag of the base wing. The drag of the base wing increased by 25 % as the angle of attack of the Clark Y tip increased from 0° to 15°. The base wing drag decreased by 6 % for the same change in the angle of attack of the feathered tip. 6. The total drag of the wing with the feathered tip was 12 % less than that of a hypothetical wing with the same lift and span, but with tip feathers that did not respond to upwash at the end of the base wing. This value is consistent with wing theory predictions on drag reduction from winglets. 7. Wings with the tip and the base wing locked together had lift and drag that increased with increasing base wing angle of attack, as expected for conventional wings. Span factors were calculated from these data - a large span factor indicates that a wing has low induced drag for a given lift and wing span. The wing with the Clark Y tip had a span factor that decreased from 1 to 0.75 as the angle of attack of the base wing increased. Over the same range of angle of attack, the span factor of the wing with the feathered tip remained constant at 0.87. As the angle of attack of this wing increased, aerodynamic forces spread the feathers vertically to form slots. With fully formed slots, the wing had a higher span factor than the wing with the unslotted Clark Y tip. 8. Flow visualization with helium-filled bubbles showed that the addition of two winglets to the tip of a model wing spread vorticity both horizontally and vertically in the wake of the tip. 9. These observations taken together provide strong evidence that the tip slots of soaring birds reduce induced drag in the sense that the separated tip feathers act as winglets and increase the span factor of the wings.
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Starr, Philip A., Nicholas M. Barbaro, Neil H. Raskin, and Jill L. Ostrem. "Chronic stimulation of the posterior hypothalamic region for cluster headache: technique and 1-year results in four patients." Journal of Neurosurgery 106, no. 6 (2007): 999–1005. http://dx.doi.org/10.3171/jns.2007.106.6.999.
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Object Cluster headache (CH) is the most severe of the primary headache disorders. Based on the finding that regional cerebral blood flow is increased in the ipsilateral posterior hypothalamic region during a CH attack, a novel neurosurgical procedure for CH was recently introduced: hypothalamic deep brain stimulation (DBS). Two small case series have been described. Here, the authors report their technical approach, intraoperative physiological observations, and 1-year outcomes after hypothalamic DBS in four patients with medically intractable CHs. Methods Patients underwent unilateral magnetic resonance (MR) imaging–guided stereotactic implantation of a Medtronic DBS (model 3387) lead and Soletra pulse generator system. Intended tip coordinates were 3 mm posterior, 5 mm inferior, and 2 mm lateral to the midcommissural point. Microelectrode recording and intraoperative test stimulation were performed. Lead locations were measured on postoperative MR images. The intensity, frequency, and severity of headaches throughout a 1-week period were tracked in patient diaries immediately prior to surgery and after 1 year of continuous stimulation. At the 1-year follow-up examination, DBS had produced a greater than 50% reduction in headache intensity or frequency in two of four cases. Active contacts were located 3 to 6 mm posterior to the mammillothalamic tract. Neurons in the target region showed low-frequency tonic discharge. Conclusions In two previously published case series, headache relief was obtained in many but not all patients. The results of these open-label studies justify a larger, prospective trial but do not yet justify widespread clinical application of this technique.
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Novianti, Titta, Febriana Dwi Wahyuni, It Jamilah, and Syafruddin Ilyas. "Histology Analysis of Tissue Regeneration Process of Digit Tip Mice (Mus musculus) post amputation." Indonesian Journal of Biotechnology and Biodiversity 4, no. 2 (2020): 112–17. http://dx.doi.org/10.47007/ijobb.v4i2.70.
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The ability to regenerate tissue is different for each organism. Mice (Mus musculus) able to regenerate the 3rd phalange of a digit. The tissue regeneration process has four phases are the wound-healing phase, the blastema phase, the regeneration phase, and the maturation phase. Each phase has a different process and different activity of cells. Histological analysis is very important to see the activity of each cell in each phase of tissue regeneration. Through histological analysis we can find out the role of each cell in the tissue regeneration process as well as the processes that occur in tissue regeneration. In this study, we analyzed tissue histology in the digit tip mice at each regeneration phase post amputated. The phalanges were amputated on the 3rd phalanges of digit tip of 24 male mice which had been previously sedated using ketamine / xylazine. Digit tip were allowed to grow and regenerate, and samples were taken on days 0, 1, 3, 5, 10, 15, 25 after amputation. Histological analysis was performed using Hematoxylin-eosin staining on a sample preparation that had been made into paraffin blocks first. The histological showed that at the beginning of the wound, the tissue rapidly forms a thin epidermal layer to cover the wound. In the wound healing phase, some of embryonal cells proliferated and migrated actively. In the blastema phase, granule cells cluster to form various new tissues. In the regeneration phase, new tissue begins to form, such as blood vessel, muscle, bone, and epidermal tissue. In the regeneration phase on day 15, several new tissues have begun to form, such as blood vessel tissue, muscle, hemorrhoid, bone and epidermis. Finally, in the maturation phase on day 25, the tissue morphology process occurs and perfecting the digit tip mice tissue.
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Domagalska-Szopa, Małgorzata, and Andrzej Szopa. "Body Posture Asymmetry Differences between Children with Mild Scoliosis and Children with Unilateral Cerebral Palsy." BioMed Research International 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/462094.
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Patients with unilateral cerebral palsy (CP) often have impaired movement coordination, reduced between-limb synchronization, and less weight bearing on the affected side, which can affect the maintenance of an upright weight-bearing position and gait. This study evaluated whether the different postural patterns of children with unilateral CP could be statistically recognized using cluster analysis. Forty-five outpatients with unilateral CP (mean age, 9 years and 5 months) and 51 able-bodied children with mild scoliosis (mean age, 9 years and 2 months) were included. One observer performed moiré topography (MT) examinations using a CQ Electronic System (Poland) device. A weight distribution analysis on the base of support (BOS) between the body sides was performed simultaneously. A force plate dynamographic platform (PDM), ZEBRIS (Germany), with FootPrint software was used for these measurements. Cluster analysis revealed three groups: Cluster 1 (, 73.96%), Cluster 2 (, 8.33%), and Cluster 3 (, 17.71%). Based on the MT parameters (extracted using a data reduction technique), three typical asymmetrical postural patterns were described: (1) the postural pattern of children with mild scoliosis (SCOL), (2) the progravitational postural pattern (PGPP), and (3) the antigravitational pattern. Patterns two and three were identified in children with unilateral CP.
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Xavier, Warlles D., Diogo C. Silva, Rommel B. da Costa, Diego O. Ribeiro, Vinicius S. Sousa, and João Vitor de S. Silva. "Losses in the mechanized harvesting of sugarcane as of speed function of two harvester models in Tropical Savanna Environment." April 2020, no. 14(04):2020 (April 20, 2020): 675–82. http://dx.doi.org/10.21475/ajcs.20.14.04.p2338.
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The aim of this study was to evaluate the losses that occur in the sugarcane crop during the harvesting, based on the performance of two harvester models operated at different displacement speeds. The variety harvested was CTC4, with total productivity of 95.0 Mg ha-1. The experimental design was completely randomized in a 2 x 3 factorial scheme with five replications. The treatments consisted of two harvester models (John Deere 3520 and John Deere CH570), operated in three different displacement speeds (3.0 km h-1, 4.0 km h-1 and 5.0 km h-1) in sugarcane harvesting. The quality indicators that assessed after sugarcane harvesting were the following loss types: stump cane, whole cane, tip cane, loose piece cane, shrapnel cane and total cane loss in Mg ha-1. The increase in displacement speed resulted in lower total losses in sugarcane harvesting. The 3520 harvester was superior to the CH570 at the highest speed tested. The reduction of sugarcane harvesting loss indexes was proportional to the increase of the displacement speeds for the parameters such as stump cane, whole cane, tip cane, loose piece cane and total loss cane for 3520 harvester and stump cane, whole cane and total loss cane for CH570 harvester, showing strong negative correlations (> 0.85).
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WUTTKE, WERNER A., ROY T. SAWYER, and MICHAEL S. BERRY. "EXTRAGLANDULAR INNERVATION OF THE SALIVARY CELLS OF THE LEECH HAEMENTERIA GHILIANII: NEURONAL STIMULATION ELICITS GLAND-CELL ACTION POTENTIALS AND SECRETION." Journal of Experimental Biology 143, no. 1 (1989): 389–410. http://dx.doi.org/10.1242/jeb.143.1.389.
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1. Each salivary gland cell of Haementeria extends a single process, or ductule, anteriorly into the proboscis; secretory products are released at the ductule ending. Some ductules secrete into the lumen of the proboscis and others at the outer surface of its tip, more than 5 cm from the gland in large leeches 2. Depolarization of a gland-cell body elicits action potentials which appear to be conducted along the ductule to its ending. Electrical stimulation of the proboscis tip elicits action potentials in those ductules which end there, and the impulses are propagated to the cell body (approx. 5cms−1) 3. Bathing the salivary glands in calcium-free saline causes spontaneous repetitive firing in the cell bodies and also elicits secretion at the proboscis tip (bathed in normal saline); the action potential thus appears to be a stimulus for secretion 4. A paired stomatogastric nerve, from the brain, enters the proboscis near its base. Cobalt-filling of the nerve shows numerous cell bodies in the brain and first body ganglion, and an intricate network of fibres and a cluster of stained cell bodies near its entry point in the proboscis 5. Repetitive stimulation of the stomatogastric nerve produces action potentials in certain gland cells, after a delay of at least 15 s, and also elicits secretion. The action potentials are initiated near the ductule tip, and are conducted to the cell body. The salivary glands themselves do not appear to be innervated 6. Application of acetylcholine (ACh), dopamine or octopamine (10−4 moll−1) does not initiate secretion. Neither dopamine nor octopamine excites the gland cells but ACh produces a transient suprathreshold depolarization of the cell body and occasionally elicits 1–3 ductule spikes when applied to the proboscis tip. 5-Hydroxytryptamine (5-HT) produces secretion when applied to the proboscis but not when applied to the glands alone; it does not excite the cells, indicating that the action potential is not the only stimulus for secretion. 5-HT produces a depolarization, and increase in membrane resistance, in the cell body, and prevents the rapid adaptation of action potentials which occurs during maintained depolarization 7. Electrophoretic analysis shows that the protein compositions of secretions at the proboscis tip and in the lumen are completely different, with the tip apparently secreting only two major proteins. These same two protein bands occur in the cytoplasm of certain gland-cell bodies which can be distinguished in living glands on the basis of size and degree of staining with Methylene Blue 8. Following stimulation of the stomatogastric nerve, secretory products at the proboscis tip can be seen to emerge from discrete points which appear to be single ductule endings. This presents the possibility of studying excitation-secretion coupling in single cells
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Gerasimchuk, M. Yu. "CHARACTERISTICS OF DEPRESSION IN PATIENTS WITH DIFFERENT CHRONOTYPES." Annals of the Russian academy of medical sciences 72, no. 6 (2017): 435–41. http://dx.doi.org/10.15690/vramn881.
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Background: Approximately 30−40% of depressive patients does not improve or show a partial response. Since biological rhythm involved in the pathogenesis of mood disorders is regarded as a unique characteristic of a person, it opens new opportunities for personalized medicine.Aim: to evaluate clinical characteristics and treatment effectiveness in depressive patients with different chronotypes.Materials and methods: In prospective, hospital-based study MADRS was performed weekly (dMADRS), therapeutic response (R) was defined as a 50% or greater decrease from baseline in the score. Chronotype was evaluated using the Morningness−Eveningness Questionnaire (MEQ). Participants completed a questionnaire package: HDRS-21, PSQI, ТОВ, «individual minute». Statistical analysis was performed using Excel for Windows, Statistica 13.0.Results: All patients (n=100, mean age 48±16 yrs) were divided into groups based on their circadian type: evening types (ETs) had more severe condition; antidepressants (SSRIs; R=72%) were effective given at morning in ETs, at evening (other; R=100%) ― in morning types (MTs) (p0.00001) with a greater reduction in depressive symptoms (p0.05). Prescribing drugs with balanced potency were effective in both groups (F=4.62, p=0.032). Cluster analysis on 25 clinical, biological, and therapeutic variables to establish the role of chronotype as a factor important for identifying patients with similar socio-demographic, clinical, and health characteristics was conducted. Cluster 1 achieved a reduction of depression severity (19% MTs; R=81%; 43.4±17.7 yrs; single episode; dMADRS 16.9±2.7; 23% monotherapy). Cluster 3 (80% ETs; R=50%; 40.4±15.2; early onset dMADRS 15.23±2.29; 7% monotherapy) was the most unfavorable prognostic group.Conclusions: Depressive patients with morning/evening chronotypes have significant differences in clinical presentation, the course of the illness and efficacy of antidepressants. Evening chronotype was found to be associated with poor prognosis. Circadian typology should be considered when choosing the appropriate therapeutic options.
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Zhuang, Rulong, Kena Mi, and Zhangwei Feng. "Industrial Co-Agglomeration and Air Pollution Reduction: An Empirical Evidence Based on Provincial Panel Data." International Journal of Environmental Research and Public Health 18, no. 22 (2021): 12097. http://dx.doi.org/10.3390/ijerph182212097.
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Industrial co-agglomeration plays a significant role in the moving up of the manufacturing industry in the value chain and in transforming China from a manufacturing giant into a world manufacturing power. This study establishes a co-aggregation index to explore spatio-temporal changes of the co-agglomeration between manufacturing and producer services in 30 provinces of China from 2004 to 2019. Furthermore, we use spatial Durbin model to analyze the impact of industrial co-agglomeration on air pollution reduction. We find that (1) the co-agglomeration index varies remarkably at spatio-temporal scale; (2) high co-agglomeration index is mainly distributed in eastern and central China, while low co-agglomeration index is mainly located in the western region; (3) the co-agglomeration index presents a cluster pattern among provinces, with the cluster of high value in eastern China and the cluster of low value in western China; and (4) the co-agglomeration between manufacturing and producer services is proven effetely to reduce air pollution, which is accompanied with spatial spillover effect. We also provided policy implications in line with diverse industries, multi hierarchies, and different regions, promoting the coordination of manufacturing and producer services and improving air quality.
Conference papers on the topic "Different cluster tip reduction (1/3"
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A., Abhishek, and Rahul R. "Investigation of Tip-Vortex Modifications on Rotor Loads and Performance." In Vertical Flight Society 71st Annual Forum & Technology Display. The Vertical Flight Society, 2015. http://dx.doi.org/10.4050/f-0071-2015-10158.
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This paper studies the influence of tip vortex modification on the airloads and performance of the helicopter for high speed steady level flight and unsteady maneuver using a lifting-line based comprehensive analysis. The tip vortex modification is modeled inside the free wake model of the comprehensive analysis in three different ways: (1) the location of tip vortex release point is altered, keeping the strength constant, (2) strength of the tip vortex is diminished by certain factor while keeping the release location constant, and (3) both the release location and strength of the vortex are altered simultaneously. The modification of tip vortex release location is observed to have significant influence on rotor power during both steady and unsteady flight conditions analyzed. Moving the tip vortex outboard of blade tip by 5%, 10%, 15% and 20% of chord in the simulation resulted in power reduction ranging from 11.5%-18.5%, 20%-32.5%, 28%-46% and 35%-59% respectively for the unsteady pull-up maneuver.
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Yang, Dianliang, and Zhenping Feng. "Tip Leakage Flow and Heat Transfer Predictions for Turbine Blades." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27728.
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A numerical study was performed to simulate the tip leakage flow and heat transfer on the first stage rotor blade in GE-E3 engines. Calculations were performed for both flat and squealer blade tips by means of solving Reynolds-averaged N-S equations in conjunction with the k-ω two-equation turbulence model. For squealer tip blades, several cases were considered with five different tip gap-blade span ratios of 0.4%, 0.7%, 1.0%, 1.3%, and 1.6%, and four different groove depth-blade span ratios of 1%, 2%, 3%, and 4%. A linear experimental cascade was calculated first to validate this turbulence model, and the results show good agreement with that of the experiment. With the results of several cases discussed and compared, flow structure and heat transfer characteristics in the tip gap are illustrated. The effects of the tip gap and groove depth on flow and heat transfer are significant. The leakage flow is weakened by deepening the tip groove. However, when the groove depth is larger than 3% of the blade span, no further leakage flow reduction will occur. The average heat transfer rate on the tip surface reduces as groove depth increases. An increase in tip gap height will increase the leakage flow, and thus lead to an increase in average heat transfer rate on the tip surface.
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Ameri, A. A., E. Steinthorsson, and David L. Rigby. "Effects of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficiency in Axial Turbines." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-369.
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Calculations were performed to assess the effect of the tip leakage flow on the rate of heat transfer to blade, blade tip and casing. The effect on exit angle and efficiency was also examined. Passage geometries with and without casing recess were considered. The geometry and the flow conditions of the GE-E3 first stage turbine, which represents a modern gas turbine blade were used for the analysis. Clearance heights of 0%, 1%, 1.5% and 3% of the passage height were considered. For the two largest clearance heights considered, different recess depths were studied. There was an increase in the thermal load on all the heat transfer surfaces considered due to enlargement of the clearance gap. Introduction of recessed casing resulted in a drop in the rate of heat transfer on the pressure side but the picture on the suction side was found to be more complex for the smaller tip clearance height considered. For the larger tip clearance height the effect of casing recess was an orderly reduction in the suction side heat transfer as the casing recess height was increased. There was a marked reduction of heat load and peak values on the blade tip upon introduction of casing recess, however only a small reduction was observed on the casing itself. It was reconfirmed that there is a linear relationship between the efficiency and the tip gap height. It was also observed that the recess casing has a small effect on the efficiency but can have a moderating effect on the flow underturning at smaller tip clearances.
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Krishnababu, S. K., H. P. Hodson, G. D. Booth, G. D. Lock, and W. N. Dawes. "Aero-Thermal Investigation of Tip Leakage Flow in a Film Cooled Industrial Turbine Rotor." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50222.
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A numerical investigation of the flow and heat transfer characteristics of tip leakage in a typical film cooled industrial gas turbine rotor is presented in this paper. The computations were performed on a rotating domain of a single blade with a clearance gap of 1.28% chord in an engine environment. This standard blade featured two coolant and two dust holes, in a cavity-type tip with a central rib. The computations were performed using CFX 5.6, which was validated for similar flow situations by Krishnababu et al., [18]. These predictions were further verified by comparing the flow and heat transfer characteristics computed in the absence of coolant ejection with computations previously performed in the company (SIEMENS) using standard in-house codes. Turbulence was modelled using the SST k-ω turbulence model. The comparison of calculations performed with and without coolant ejection has shown that the coolant flow partially blocks the tip gap, resulting in a reduction of the amount of mainstream leakage flow. The calculations identified that the main detrimental heat transfer issues were caused by impingement of the hot leakage flow onto the tip. Hence three different modifications (referred as Cases 1 to 3) were made to the standard blade tip in an attempt to reduce the tip gap exit mass flow and the associated impingement heat transfer. The improvements and limitations of the modified geometries, in terms of tip gap exit mass flow, total area of the tip affected by the hot flow and the total heat flux to the tip, are discussed. The main feature of the Case 1 geometry is the removal of the rib and this modification was found to effectively reduce both the total area affected by the hot leakage flow and total heat flux to the tip while maintaining the same leakage mass flow as the standard blade. Case 2 featured a rearrangement of the dust holes in the tip which, in terms of aero-thermal-dynamics, proved to be marginally inferior to Case 1. Case 3, which essentially created a suction-side squealer geometry, was found to be inferior even to the standard cavity tip blade. It was also found that the hot spots which occur in the leading edge region of the standard tip and all modifications contributed significantly to the area affected by the hot tip leakage flow and the total heat flux.
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Hustad, C.-W., A. Bölcs, and M. Wehner. "Investigation of Tip Leakage Effects in Transonic Flow Using a Parallel Unstructured Navier-Stokes Code." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-202.
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Calculated results for tip flow around two different blade configurations are presented and compared with experimental data. The first configuration (case number 1) is a flat-plate profile tested in a linear transonic tunnel — the profile is an idealized representation of the aft-section of some highly curved turbine blades. The second configuration (case number 2) originates from the outer profile on the last-stage-blade of a steam turbine, however it is also reminiscient of a section from a turbine blade with supersonic exit flow. This configuration was tested in an annular cascade at Mach numbers representative of engine operating conditions. The computed results were obtained using a parallel 3D unstructured Navier-Stokes code. The code runs on a work-station cluster, as well as being optimized for the 256 processor Cray T3D at EPFL: the code is capable of gigaflop performance using more than 3 million cells — adaptive mesh refinement thus allows enhanced resolution within the tip gap region. For each configuration we have calculated two Runs. In both cases, Run-1 is similar to the experimental conditions, so that direct comparison between measured and calculated results is possible. With case number 1/Run-2 we re-calculated the flow without imposing a prescribed inflow boundary-layer along the sidewall. Comparison between the two runs helped reveal how free-stream total pressure can establish itself within the tip gap region. For the second configuration — in the annular cascade — we were interested in observing the influence of relative movement between the blade tip and adjacent sidewall. Hence for case number 2/Run-2 we imposed a circumferential velocity on the adjacent sidewall. This modified the effective sidewall boundary-layer and had a noticeable influence on the development of the tip-leakage flow.
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Van Treuren, Kenneth, and Charles Wisniewski. "Testing Propeller Tip Modifications to Reduce Acoustic Noise Generation on a Quadcopter Propeller." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90534.
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Abstract Electric propulsion is gaining popularity with over 100 electrically propelled aircraft in development worldwide. There is a growing interest in vertical lift vehicles either for package delivery or for urban air taxis. If these vehicles are to operate near population centers, they must be both quiet and efficient. The goal of this research is to develop a propeller that is more efficient and generates less noise than a stock DJI Phantom 2 quadcopter propeller. Since a large contribution of near field noise generation for a propeller comes from the tip vortex, reducing or minimizing this generated tip vortex was the main objective. After studying the literature on aircraft wing tip vortices and techniques proposed to minimize the wing tip vortex, seven promising tip treatments were selected and applied to a stock DJI Phantom 2 propeller in an attempt to reduce the tip vortex, and, thus, the generated noise. These tip treatments were: 1. Leading Edge Notch, 2. Trailing Edge Notch, 3. Hole, 4. Vortex Generators, 5. Tip Thread, 6. Trailing Edge Sawtooth, and 7. Reverse Half-Delta. An optimum design would be one that reduces near field noise while at the same time minimizes any additional required power. Several different configurations were tested for each tip treatment to determine the RPM and required power to hold 0.7 lbf thrust, which simulated a static hover condition. For each test, a radial traverse one inch behind the propeller permitted the measurement of the Sound Pressure Level (SPL) to find the maximum SPL and its radial location. Several configurations tested resulted in 8–10 dBA reductions in SPL when compared to the stock propeller, however, these configurations also resulted in an unacceptable increase in the power required to achieve the desired thrust. Thus, in these cases a decrease in SPL comes at the expense of power, a tradeoff that must be considered for any propeller modification. The most promising tip treatment tested was the Trailing Edge Notch at a radial location of 0.95 r/R with a Double Slot width and a Double Depth (DSDD). The DSDD configuration as tested reduced the SPL 7.2 dBA with an increase in power required of only 3.96% over the stock propeller. This tradeoff, while not the largest reduction in noise generation measured, seems to be an acceptable power increase for the decrease in SPL achieved. Smoke visualization confirms that the tip vortex is minimized for this configuration.
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Al-Saeed, A., and Y. Al-Salali. "Production Enhancement & Cost Effective of Deep Gas Wells by Using Cluster Perforation Technique of Carbonate Reservoirs in Kuwait: Case Studies." In SPE Conference at Oman Petroleum & Energy Show. SPE, 2024. http://dx.doi.org/10.2118/218684-ms.
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Abstract North Kuwait Jurassic Gas (NKJG) fields are challenging HPHT wells with near-critical fluids in reservoir conditions. These wells are deep and sour with 2-8 % H2S and 1-3 % CO2 with average reservoir pressure ranging from 10,000 – 4,000 psi and average reservoir temperature of ~275oF. Best practices in terms of developing these fields by using the best technologies in drilling, completion, and production are essential to maximize the reserve recovery in order to deliver hydrocarbon to the market. Due to anhydrite presence and existing high variation of natural fracture distribution along the wellbore with different lithology and reservoir properties. There is differential pressure depletion happens within the entire reservoir, so these reservoirs have been divided into different flow units based on stratigraphy and pressure differential. These layers have different productivity index based on production logging records and calibrated well production models due to existence of dual-porosity tight matrix with natural fracture system which require proper pinpoint activation protocol by treating these layers separately. During the early development stages of these fields, these wells were completed with tapered type of completion with 3.5″ production tubing, which was used as the optimum flow rate for virgin or slightly depleted reservoirs. Nowadays, Monobore completion has been deployed so that these flow zones can be perforated, activated, stimulated, tested and isolated using plug and perf technique which provide proper stimulation fluids propagation into the target reservoir. In addition, the cluster perforation leads to better effective stimulation fracturing by bypassing formation damage due to drilling, completion & perforation debris from the illustrated case studies. This paper aims to illustrate the successful story of the cluster perforation technique in tight carbonate reservoir layers, and share its impact on pinpoint stimulation and hydraulic fracturing treatment by comparing the production performance of the studied wells with offset wells. As an additional achievement, the cluster perforation leads to cost reduction by reducing the perforation gun length, volumes of pumped treatment/wellbore diverters fluids and accelerating the well hookup to the production facility beside the sustainability of the production during the LTT. Also, that technique is better in terms of reservoir management as it supports depleting the reservoir layers uniformly. The success of this approach was proven by calibrated nodal analysis assessment and sustainability of well production at a stabilized rate, which supports reaching "optimal inflow distribution" along the different flow zones, which become a best practice approach in the newly completed wells aiming to maximize the gas recovery.
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Alusta, Gamal, Hossein Algdamsi, Ahmed Amtereg, Ammar Agnia, Ahmed Alkouh, and Bacem Kcharem. "Integration of Self Organizing Map and Date Driven Methods to Predict Oil Formation Volume Factor: North Africa Crude Oil Examples." In SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205782-ms.
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Abstract In this paper we introduce for the first time an innovative approach for deriving Oil Formation Volume Factor (Bo) by mean of artificial intelligence method. In a new proposed application Self-Organizing Map (SOM) technology has been merged with statistical prediction methods integrating in a single step dimensionality reduction, extraction of input data structure pattern and prediction of formation volume factor Bo. The SOM neural network method applies an unsupervised training algorithm combined with back propagation neural network BPNN to subdivide the entire set of PVT input into different patterns identifying a set of data that have something in common and run individual MLFF ANN models for each specific PVT cluster and computing Bo. PVT data for more than two hundred oil samples (total of 804 data points) were collected from the north African region representing different basin and covering a greater geographical area were used in this study. To establish clear Bound on the accuracy of Bo determination several statistical parameters and terminology included in the presentation of the result from SOM-Neural Network solution. the main outcome is the reduction of error obtained by the new proposed competitive Learning Structure integration of SOM and MLFF ANN to less than 1 % compared to other method. however also investigated in this work five independents means of model driven and data driven approach for estimating Bo theses are 1) Optimal Transformations for Multiple Regression as introduced by (McCain, 1998) using alternating conditional expectations (ACE) for selecting multiple regression transformations 2), Genetic programing and heuristic modeling using Symbolic Regression (SR) and cross validation for model automatic tuning 3) Machine learning predictive model (Nearest Neighbor Regression, Kernel Ridge regression, Gaussian Process Regression (GPR), Random Forest Regression (RF), Support Vector Regression (SVM), Decision Tree Regression (DT), Gradient Boosting Machine Regression (GBM), Group modeling data handling (GMDH). Regression Model Accuracy Metrics (Average absolute relative error, R-square), diagnostic plot was used to address the more adequate techniques and model for predicting Bo.
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Heitzig, Stefan, Gregor Bultel, and Hubertus Murrenhoff. "Efficiency Improvement of Common-Rail Pumps by Gap Compensation Based on Hollow Pistons." In ASME/BATH 2015 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fpmc2015-9528.
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In the scope of the cluster of excellence “Tailor-Made Fuels from Biomass” new biofuels are developed. To ensure safe and reliable functioning of the injection system operating with the new fuels, the tribological characteristics of the fuel candidates have to be investigated. The biofuel candidates which have been studied so far tend to have a lower viscosity compared to diesel [1]. This has an enormous impact on the efficiency of common-rail piston pumps. For low viscosity fuels the volumetric losses become the dominant factor. These losses are influenced by the geometric parameters of the pump, the operating conditions and the rheological characteristics of the fuels. Regarding the geometric parameters, the gap height in the piston-cylinder-contact is the predominant factor. In modern common-rail pumps the nominal gap height is in the range of 2–3 μm [2]. A further reduction of the height is limited by tolerances of the manufacturing process and the risk of the piston getting stuck in the cylinder due to different temperature gradients and consequently different thermal expansions of piston and cylinder. Besides the nominal gap height, the high pressure in the lubricating film in operation leads to an expansion of the gap. If this expansion can be limited or even avoided, a significant reduction of the leakage losses will be possible. In the scope of this paper an approach to a gap compensation of the sealing and lubricating contact between piston and cylinder is presented. Based on a detailed study of the state of the art design, including efficiency measurements of pumps and EHD-simulation, a modified piston design is investigated and optimized. The results show a great potential for efficiency improvement of common-rail pumps, especially if operated with biofuels, which provide low viscosities.
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Peng, C., H. L. Zhang, J. H. Fu, et al. "Intelligent Identification of Formation Lithology While Drilling." In International Petroleum Technology Conference. IPTC, 2025. https://doi.org/10.2523/iptc-24708-ms.
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Abstract During drilling engineering, the rate of penetration (ROP) is the basic index to measure the drill ability of various rocks, and drilling parameters are the main control factors that affect the ROP. Identifying formation lithology while drilling can promptly adjust drilling parameters and effectively improve drilling efficiency. In this paper, drilling parameters and intelligent models are combined to realize formation lithology identification while drilling. Different from previous research, this method uses K-means, Fuzzy C-means (FCM), and Mean Shift algorithms to cluster the data set after dimension reduction, uses support vector machine (SVM), random forests (RF), and extremely randomized trees (ET) algorithms to train multiple models to identify formation lithology according to the clustering results, and analyzes the identification accuracy of the models under different combinations of dimension reduction and clustering methods. The results indicate that: 1) without clustering, the accuracy of the model in identifying formation lithology is poor, and the final identification result is biased towards one or two types of lithology; 2) the linear kernel function is the best among the three kernel functions, and the classification results lead to high accuracy in identifying lithology. The classification results of the Gaussian kernel function and polynomial kernel function are biased towards a certain kind of lithology; 3) in the multi-model of linear kernel function + K-Means + SVM, the identification accuracies of sandstone, mudstone, limestone, and shale are 60%, 80%, 70%, and 90% respectively, with an average identification accuracy of 82.5%. This paper puts forward a method for identifying formation lithology while drilling by combining drilling parameters and intelligent models, and takes the YX block as an example to carry out application test. The results show that this method can effectively improve the accuracy of lithology identification while drilling.