Use Of Sweeps Research Articles

Reduction in endwall flow losses in turbine blade with the use of sweep in leading edge of the blade

Reduction in endwall flow losses in turbine blade with the use of sweep in leading edge of the blade

Efficacy of various activation techniques on tubule penetration of resin-based and bioceramic root canal sealers: An in vitro confocal microscopy study.

To compare the penetration of Ah Plus and MTA Fillapex after irrigation activation with sonic, passive ultrasonic, SWEEPS and XP-Endo Finisher using confocal microscopy. Instrumented root canals of 160 mandibular premolar teeth were allocated randomly to four groups (n = 40/group) and eight subgroups according to the activation techniques and canal sealers (n = 20/subgroup). After the obturation, three sections at 1-2, 5-6 and 9-10 mm levels from the apex were examined. Penetration area and maximum penetration depth values were represented as mean and standard deviation, and results below 0.05 were considered statistically significant. For penetration area and maximum penetration depth, the statistical difference was found in terms of material, device and region (Maximum penetration depth: p = 0.006, p < 0.001, p < 0.001; Penetration area: p = 0.004, p < 0.001, p < 0.001). SWEEPS was found to be relatively higher than other groups. Sealers presented similar results when evaluated independently of the region. The use of SWEEPS for irrigation activation is promising in terms of tubule penetration.

Ultra-compact microstructured methane steam reformer with integrated Palladium membrane for on-site production of pure hydrogen: Experimental demonstration

A novel metal-based modular microstructured reactor with integrated Pd membrane for hydrogen production by methane steam reforming is presented. Thin Pd foils with a thickness of 12.5 μm were leak-tight integrated with laser welding between microstructured plates. The laser-welded membrane modules showed ideal H2/N2 permselectivities between 16,000 and 1000 at 773 K and 6 bar retentate pressure. An additional metal microsieve support coated with an YSZ diffusion barrier layer (DBL) facilitated the operation at temperatures up to 873 K and pressures up to 20 bar pressure difference. The membrane permeability in this configuration is expressed with Q = 1.58E-07*exp(−1460.2/T) mol/(msPa0.5).In the first proof-of-concept reaction experiments the influence of W/F ratio (0.33–1.32gCath/molCH4), S/C ratio (3 and 4), temperature (773 and 823 K) and retentate/reformate pressure (6–12 bar) was studied. Methane conversion of 87% and a hydrogen recovery of 92% were obtained at a W/F ratio of 0.33gCath/molCH4, corresponding to a GHSV of 29,000 h−1, a temperature of 823 K and a feed pressure of 12 bar without the use of sweep gas.The microstructured membrane reactor showed a promising performance for the production of pure hydrogen in a very compact and modular system.

Sweep seed drill for intercultural operation along with sowing of soybean (Glycine max) crop

A field experiment was conducted to study the effect of planting by tractor-drawn sweep seed drill, on growth and yield performance of soybean, weed population and economics. A Tractor drawn sweep seed drill, attachable on 30 PTO hp tractor was conceived, fabricated and validated for facilitating weeding along with sowing operations on the field prepared for soybean crop. The use of developed seed drill leads to saving of one pass tillage and one weeding operation in the initial growth period. In this way, approximately ` 3 000/ha/season could be saved from the total expenditure. The simultaneous tillage and sowing operation by the machine helps to maintain higher plant population (25.22–34.55%). This also leads to reduction of weeds (59.91– 68.37%) as compared to flat sowing method. Thus, the use of sweep seed drill curtails the cost on post sowing weedicides along with seed bed preparation as one operation of cultivator. Result of the study indicated that crop planted by the sweep seed drill showed yield increase from 7.78 to 16.46% as compared to normal seed drill. It is suggested to get tractor-operated sweep seed drill manufactured with an adjustable frame which could hold sweeps at the rear end of the frame of the seed drill and the tines for dropping seeds on the front of the seed drill frame to ensure better field operation.

On the use of a chaotic cavity transducer in nonlinear elastic imaging

We discuss the advantages of “chaotic cavity transducer focusing” to enhance the localization of microdamage in conjunction with nonlinear elastic wave spectroscopy methods. Chaotic cavity transducer focusing is defined as the hardware-software combination of a piezoelectric ceramic glued on a cavity of chaotic shape on the one hand with the reciprocal time reversal (or inverse filter) technique on the other hand. Additional optimization through the use of sweeps and inverse filtering techniques are discussed as well. The technique is applied to image a crack in a steel sample.

Membrane Sweeping for Induction of Labour

AbstractBackground: Sweeping of the membranes, also named stripping of the membranes, is a relatively simple technique usually performed without admission to hospital. During vaginal examination, the clinician's finger is introduced into the cervical os. Then, the inferior pole of the membranes is detached from the lower uterine segment by a circular movement of the examining finger. This intervention has the potential to initiate labour by increasing local production of prostaglandins and, thus, reduce pregnancy duration or pre‐empt formal induction of labour with either oxytocin, prostaglandins, or amniotomy. This is one of a series of reviews of methods of cervical ripening and labour induction using tandardized methodology.Objectives: To determine the effects of membrane sweeping for third trimester induction of labour.Search strategy: We searched the Cochrane Pregnancy and Childbirth Group trials register (6 July 2004) and bibliographies of relevant papers.Selection criteria: Clinical trials comparing membrane sweeping used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods.Data collection and analysis: A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two‐stage method of data extraction.Main results: Twenty‐two trials (2797 women) were included, 20 comparing sweeping of membranes with no treatment, three comparing sweeping with prostaglandins. And one comparing sweeping with oxytocin (two studies reported more than one comparison). Risk of caesarean section was similar between groups (relative risk (RR) 0.90, 95% confidence interval (CI) 0.70 to 1.15). Sweeping of the membranes, performed as a general policy in women at term, was associated with reduced duration of pregnancy and reduced frequency of pregnancy continuing beyond 41 weeks (RR 0.59, 95% CI 0.46 to 0.74) and 42 weeks (RR 0.28, 95% CI 0.15 to 0.50). To avoid one formal induction of labour, sweeping of membranes must be performed in eight women (NNT = 8). There was no evidence of a difference in the risk of maternal or neonatal infection. Discomfort during vaginal examination and other adverse effects (bleeding, irregular contractions) were more frequently reported by women allocated to sweeping. Studies comparing sweeping with prostaglandin administration are of limited sample size and do not provide evidence of benefit.Authors’ conclusions: Routine use of sweeping of membranes from 38 weeks of pregnancy onwards does not seem to produce clinically important benefits. When used as a means for induction of labour, the reduction in the use of more formal methods of induction needs to be balanced against women's discomfort and other adverse effects.Citation: Boulvain M, Stan C, Irion O. Membrane sweeping for induction of labour. The Cochrane Database of Systematic Reviews 2005, Issue 1. Art. No.: CD000451.pub2. DOI: 10.1002/14651858.CD000451.pub2.• • • The preceding reports are abstracts of regularly updated, systematic reviews prepared and maintained by the Cochrane Collaboration. The full text of the reviews is available in The Cochrane Library (ISSN 1464‐780X). Abstracts of Cochrane reviews are compiled and produced by Update Software Ltd on behalf of the publisher, John Wiley &amp; Sons Ltd.

Membrane sweeping for induction of labour.

Sweeping of the membranes, also named stripping of the membranes, is a relatively simple technique usually performed without admission to hospital. During vaginal examination, the clinician's finger is introduced into the cervical os. Then, the inferior pole of the membranes is detached from the lower uterine segment by a circular movement of the examining finger. This intervention has the potential to initiate labour by increasing local production of prostaglandins and, thus, reduce pregnancy duration or pre-empt formal induction of labour with either oxytocin, prostaglandins or amniotomy. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology. To determine the effects of membrane sweeping for third trimester induction of labour. We searched the Cochrane Pregnancy and Childbirth Group trials register (6 July 2004) and bibliographies of relevant papers. Clinical trials comparing membrane sweeping used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods. A strategy was developed to deal with the large volume and complexity of trial data relating to labour induction. This involved a two-stage method of data extraction. Twenty-two trials (2797 women) were included, 20 comparing sweeping of membranes with no treatment, three comparing sweeping with prostaglandins and one comparing sweeping with oxytocin (two studies reported more than one comparison). Risk of caesarean section was similar between groups (relative risk (RR) 0.90, 95% confidence interval (CI) 0.70 to 1.15). Sweeping of the membranes, performed as a general policy in women at term, was associated with reduced duration of pregnancy and reduced frequency of pregnancy continuing beyond 41 weeks (RR 0.59, 95% CI 0.46 to 0.74) and 42 weeks (RR 0.28, 95% CI 0.15 to 0.50). To avoid one formal induction of labour, sweeping of membranes must be performed in eight women (NNT = 8). There was no evidence of a difference in the risk of maternal or neonatal infection. Discomfort during vaginal examination and other adverse effects (bleeding, irregular contractions) were more frequently reported by women allocated to sweeping. Studies comparing sweeping with prostaglandin administration are of limited sample size and do not provide evidence of benefit. Routine use of sweeping of membranes from 38 weeks of pregnancy onwards does not seem to produce clinically important benefits. When used as a means for induction of labour, the reduction in the use of more formal methods of induction needs to be balanced against women's discomfort and other adverse effects.

Using sweep to extend the stall-free operational range in axial fan rotors

The paper discusses the use of sweep as a remedial strategy to control the aerodynamic limits in low-speed axial fan rotors. In this respect, the present work contributes to the understanding of the potential effect of blade lean on the shifting of the rotor stall margin. Numerical investigations have been undertaken on highly loaded fans of non-free vortex design, with the ideal total head rise coefficient typical of the industrial application range. Two rotors with identical nominal design parameters and, respectively, with 35° forward swept blades and unswept blades have been studied. The investigation has been carried out using an accurate in-house developed multilevel parallel finite element RANS solver, with the adoption of a non-isotropic two-equation turbulence closure. The pay-off derived from the sweep technology has been assessed with respect to the operating range improvement. To this end, the flow structure developing through the blade passages and downstream of the rotors, as well as loss distributions, have been analysed at design and near-peak pressure operating conditions. The analyses of three-dimensional flow structures showed that, sweeping forward the blade, the non-free vortex spanwise secondary flows are attenuated, and a control on the onset of stall is recovered. Moreover, the swept rotor features a reduced sensitivity to leakage flow effects. Consequently, it operates more efficiently approaching the throttling limit.

The Use of Sweep and Dihedral in Multistage Axial Flow Compressor Blading—Part I: University Research and Methods Development

This paper describes the introduction of 3-D blade designs into the core compressors for the Rolls-Royce Trent engine with particular emphasis on the use of sweep and dihedral in the rotor designs. It follows the development of the basic ideas in a university research project, through multistage low-speed model testing, to the application to high pressure engine compressors. An essential element of the project was the use of multistage CFD and some of the development of the method to allow the designs to take place is also discussed. The first part of the paper concentrates on the university-based research and the methods development. The second part describes additional low-speed multistage design and testing and the high-speed engine compressor design and test.

The Use of Sweep and Dihedral in Multistage Axial Flow Compressor Blading—Part II: Low and High-Speed Designs and Test Verification

This paper describes the introduction of 3-D blade designs into the core compressors of the Rolls-Royce Trent engine series with particular emphasis on the use of sweep and dihedral in the rotor designs. It follows the development of the basic ideas in a university research project, through multistage low-speed model testing, to their application to the high pressure engine compressor. An essential element of the project was the use of multistage CFD and some of the development of the method to allow the designs to take place is also discussed. Part I of the paper concentrated on the fundamental university-based research and the methods development. Part II describes additional low-speed multistage design and testing and the high-speed engine compressor designs and tests.

Stripping/sweeping the membranes for inducing labour or preventing post-term pregnancy.

Stripping or sweeping of the membranes aims to initiate labour through a cascade of physiological events. These may reduce pregnancy duration or pre-empt formal induction of labour with either oxytocin, prostaglandins or amniotomy. The objective of this review was to assess the effects of membrane sweeping to promote or induce labour on maternal and perinatal outcomes. We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register (last searched April 1998). Adequately controlled trials of digital separation of the membranes from the lower uterine segment for inducing labour or for preventing post-term pregnancy, compared to either no vaginal examination or vaginal examination for cervical assessment only without the intention to detach the membranes. Two reviewers assessed trial quality and extracted data. Fourteen trials were included. Sweeping of the membranes, performed as a general policy in women at term, was associated with reduced duration of pregnancy and the frequency of pregnancy continuing beyond 41 weeks (relative risk 0.42, 95% confidence interval 0.19 to 0.93, random effects model) and 42 weeks. After sweeping of the membranes, there was a 17% risk reduction (confidence interval 6 to 29%, random effects model) in the use of more formal methods for labour induction. There was no difference in the mode of delivery or in the risk of infection. Discomfort during vaginal examination and other adverse effects (bleeding, irregular contractions) were more frequently reported by women allocated to sweeping. Routine use of sweeping of membranes from 38 weeks of pregnancy onwards does not seem to produce clinically important benefits. When used as a means for induction of labour, the reduction in the use of more formal methods of induction needs to be balanced against women's discomfort and other adverse effects.

The dual of sweep

As an infinite union operation, sweep of a moving object through space is a powerful and natural addition to the Boolean set operations that incorporates motion-related information for the purposes of shaping, collision detection, and simulation of moving objects. Use of sweep has been hindered by limited computational support and by the fact that it is a ‘material growing’ operation, whereas many applications, such as interference elimination and mechanism design, appear to be better modeled by a ‘material removal’ operation. This article formally defines a new geometric modeling operation of unsweep. Given an arbitrary subset E of Euclidean space and a general motion M, unsweep( E, M) returns the largest subset of E that remains inside the original E under M. When M is a translation, unsweep ( E, M) naturally reduces to the standard Minkowski difference of E and the trajectory generated by the inverted motion M̂. In this sense, the operation of unsweep is a generalization of Minkowski difference that corresponds to a ‘material removal’ operation, it can be also defined as an infinite intersection operation, and is the dual of sweep in a precise set-theoretic sense. We show that unsweep has attractive theoretical and computational properties, including a practical point membership test for arbitrary general motions. Using duality, the established properties of unsweep is extended to the general sweep operation, and can be used to improve the computational support for general sweeps.

Change in Soil Microtopography by Tillage with a Sweep

Information on effects of tillage sweep geometry and operation on soil conditions, including soil surface elevation, is needed for effective design, selection, and use of sweeps for row crop cultivation and ridge construction. The effects of sweep rake angle and of operation speed and depth on changes in soil microtopography were determined. Changes in microtopography due to observed soil aggregate movement were also found. A factorial arrangement of pairs of sweeps with three geometries operated at three speeds (5, 7, and 9 km/h) and at two depths (50 and 100 mm) were used to form ridges in a field experiment.