bluuebunny/crossref_metadata_2025 huggingface dataset:
A systematic literature review of Releasing Time to Care: The Productive Ward
Authors: Wright Stella , McSherry Wilfred
Published: March 2013

Aims and objectives

This systematic review provides an overview of the literature published on Releasing Time to Care: The Productive Ward between 2005 and June 2011.

Background

Releasing Time to Care: The Productive Ward programme was developed by the NHS Institute for Innovation and Improvement and launched in England in 2007. The programme comprises thirteen modules that aim to increase time for direct patient care, improve the patient and staff experience and make changes to the ward environment to improve efficiency.

Design

A systematic literature review.

Methods

The terms ‘Releasing Time to Care’ and ‘Productive Ward’ were applied to key healthcare databases; CINAHL, Medline, Science Direct, ProQuest, Health Business Elite, British Nursing Index, Embase, Health Management Information Consortium and PsychInfo. All papers were read and subject to a quality assessment.

Results

The literature search identified 95 unique sources. A lack of research on The Productive Ward programme meant it was necessary to include non‐empirical literature. In total, 18 articles met the inclusion criteria. Seven key themes were identified: the patient and staff experience, direct care time, patient safety, financial impact, embedding and sustainability, executive support and leadership, and common barriers and determinants of success. It also highlighted areas that require further exploration such as long‐term sustainability of the programme and consistent data measurement between organisations.

Conclusion

The review tentatively reports how The Productive Ward programme has been used to transform nursing practice for the benefit of patients and frontline staff, and how it resulted in cost savings. The literature review identified a potential positive results bias in the current literature whereby favourable outcomes were reported.

Relevance to clinical practice

This paper summarises the types of evidence and current literature on The Productive Ward providing a reference for frontline staff implementing the programme.
Towards 2015: post‐partum haemorrhage in sub‐Saharan Africa still on the rise
Authors: Mpemba Faraja , Kampo Sylvanus , Zhang Xinyu
Published: March 2013

Aims and objectives

To review literature from 1996–2012 relating to factors associating with the persistent maternal mortality rate (MMR) caused by post‐partum haemorrhage (PPH) in sub‐Saharan Africa.

Background

One woman dies every seven minutes, at the same time, one‐quarter of all maternal death worldwide is being caused by PPH. The aim of United Nations Fifth Millennium Development Goal 5 is to lower MMR by three quarters between 1990–2015.

Design

Narrative literature review.

Methods

Study articles from 1996–2012 were searched in electronic databases MEDLINE, Cochrane, PubMED, Google's scholar and manual searches. Combinations of the following search words were used: post‐partum haemorrhage/bleeding, sub‐Saharan Africa/rural areas, antenatal/obstetric care/maternal mortality/skilled care at birth/maternity care/health survey. 125 article abstracts were read, and 50 full articles used in this review.

Results

Every day about 800 women died due to birth complications in 2010: of the 800 maternal deaths worldwide, 440 occurred in sub‐Saharan Africa with PPH being the main cause. Common causes of PPH are related to failure of the healthcare system, inaccurate estimation of blood loss after delivery and lack of skills to prevent and manage PPH.

Discussion

Special attention is needed with emphasis on regular attendance of antenatal clinic, proper information concerning pregnancy and delivery, skills to accurate estimate blood loss, and prevention and management of PPH.

Conclusion

PPH is the leading cause of MMR in areas where essential care and skilled health attendants are limited. Basic Emergency Obstetric Care and arrangements for timely referral to the big hospital with facilities must be practiced everywhere.

Relevance to clinical practice

This review may help to remind health workers and the government that maternal mortality due to PPH is still higher and more interventions are needed.
Moral distress: levels, coping and preferred interventions in critical care and transitional care nurses
Authors: Wilson Melissa A , Goettemoeller Diana M , Bevan Nancy A , McCord Jennifer M
Published: March 2013

Aims and objectives

To examine the level and frequency of moral distress in staff nurses working in two types of units in an acute care hospital and to gather information for future interventions addressing moral distress.

Background

In 2008, the American Association of Critical Care Nurses published a Position Statement on Moral Distress. Nurses working in units where critically ill patients are admitted may encounter distressing situations. Moral distress is the painful feelings and/or psychological disequilibrium that may occur when taking care of patients.

Design

An exploratory, descriptive design study was used to identify the type and frequency of moral distress experienced by nurses. The setting was an acute care hospital in which the subjects were sampled from two groups of nurses based on their unit assignment.

Methods

A descriptive, questionnaire study was used. Nurses completed the 38‐item moral distress scale, a coping questionnaire, and indicated their preferred methods for institutional support in managing distressing situations. A convenience sample of staff nurses was approached to complete the moral distress questionnaire.

Results

Overall, the nurses reported low levels of moral distress. Situations creating the highest levels of moral distress were those related to futile care. A significance between group differences was found in the physician practice dimension. Specific resources were identified to help guide future interventions to recognise and manage moral distress.

Conclusion

Nurses reported lower levels and frequency of moral distress in these units but their open‐ended responses appeared to indicate moral distress. Nurses identified specific resources that they would find helpful to alleviate moral distress.

Relevance to clinical practice

There are numerous studies that identify the situations and the impact of moral distress, but not many studies explore treatments and interventions for moral distress. This study attempted to identify nurse preferences for lessening the impact of moral distress.
Cytotoxic T Lymphocyte Antigen–4 +49A/G polymorphism does not affect susceptibility to autoimmune hepatitis
Authors: van Gerven Nicole M. F. , de Boer Ynto S. , Zwiers Antonie , van Hoek Bart , van Erpecum Karel J. , Beuers Ulrich , van Buuren Henk R. , Drenth Joost P. H. , den Ouden Jannie W. , Verdonk Robert C. , Koek Ger H. , Brouwer Johannes T. , Guichelaar Maureen M. J. , Vrolijk Jan M. , Kraal G. , Mulder Chris J. J. , van Nieuwkerk Carin. M. J. , Bouma Gerd ,   the Dutch Autoimmune Hepatitis Study group
Published: March 2013

Background & Aims

Single nucleotide polymorphisms (SNP) in the Cytotoxic T lymphocyte antigen‐4 gene (CTLA‐4) have been associated with several autoimmune diseases including autoimmune Hepatitis (AIH). In this chronic idiopathic inflammatory liver disease, conflicting results have been reported on the association with a SNP at position +49 in the CTLA‐4 gene in small patient cohorts. Here, we established the role of this SNP in a sufficiently large cohort of AIH patients.

Methods

The study population consisted of 672 AIH patients derived from academic and regional hospitals in the Netherlands and was compared with 500 controls selected from the ‘Genome of the Netherlands’ project cohort. Genotype frequencies were assessed by PCR for patients and by whole genome sequencing for controls.

Results

No significant differences in allele frequencies were found between patients and controls (G Allele: 40% vs 39%, P = 0.7). Similarly, no significant differences in genotype frequencies between patients and controls were found. Finally, there was no relation between disease activity and the G allele or AG and GG genotypes.

Conclusion

The Cytotoxic T Lymphocyte Antigen‐4 +49 A/G polymorphism does not represent a major susceptibility risk allele for AIH in Caucasians and is not associated with disease severity at presentation.
Under the state's gaze: Upland trading‐scapes on the Sino‐Vietnamese border
Authors: Turner Sarah
Published: March 2013

Within the politically‐defined Greater Mekong Subregion (GMS), the borderlands of southeast Yunnan, China and Lào Cai province, northern Vietnam, have been categorized as being part of the GMS North‐South Economic Corridor. I argue that the creation of this subregion and corridor have been an opportunity for the governments in these locales to extend their territorialization and create new state spaces. For centuries, relatively isolated and ignored by lowland rulers, ethnic minority residents in these borderlands maintained their own culturally appropriate livelihoods, trade networks and societies. Nowadays, an increasing state presence in the uplands presents both challenges and opportunities for local populations on either side of the border, be they ethnic minorities, or Kinh (lowland Vietnamese) and Han Chinese. Contemporary border narratives gathered from local traders managing important upland commodities shed light on the means by which these borderland spaces are shaping both attractive prospects as well as restrictive constraints. Local residents fashion new trading‐scapes by drawing on kin ties, historical linkages, local indigenous knowledges and transnational societies that reach deep inside each country. As inhabitants carefully avoid or manipulate the state's gaze, I conclude that those living in the Sino‐Vietnamese borderlands possess the agency to ‘do things differently’ from hegemonic development approaches supported by GMS sponsors, and can create, maintain, support and refashion culturally appropriate trade livelihoods.
Outcomes and risk factors for hepatitis B virus (HBV) reactivation after kidney transplantation in occult HBV carriers
Authors: Chen G.‐D. , Gu J.‐L. , Qiu J. , Chen L.‐Z.
Published: March 2013

Purpose

The purpose of this study was to explore the outcomes and risk factors for hepatitis B virus (HBV) reactivation after kidney transplantation in occult HBV carriers, who are hepatitis B surface antigen (HBsAg) seronegative and hepatitis B core antibody (HBcAb) seropositive before kidney transplantation.

Methods

We retrospectively analyzed 322 occult HBV carriers who received kidney transplantation in our hospital from January 1998 to June 2008. HBsAg and HBV DNA were routinely checked for diagnosis of HBV reactivation.

Results

Our results showed that 15 cases (4.7%) of occult HBV carriers had HBV reactivation after kidney transplantation. Kaplan–Meier analysis showed that 1‐, 3‐, 5‐, and 10‐year patient survival was 86.7%, 79.4%, 72.2%, and 65.0%, respectively, in the HBV reactivation group, and was 96.1%, 93.8%, 91.5%, and 84.5%, respectively, in the non‐HBV reactivation group (log‐rank 4.12, P = 0.042). Graft survival showed no difference between these 2 groups (P > 0.05). The incidences of impairment of liver function, liver function failure, hepatocellular carcinoma, and acute rejection were significantly higher in the HBV reactivation group compared with the non‐HBV reactivation group (P < 0.05). Logistic multivariate analysis showed that older age (>60 years) and using anti‐T‐cell antibodies were independent risk factors for HBV reactivation after kidney transplantation, while being hepatitis B surface antibody (HBsAb) seropositive and using lamivudine prophylaxis could protect occult HBV carriers from HBV reactivation after kidney transplantation (P < 0.05).

Conclusion

In conclusion, our data showed that HBV reactivation may diminish the patient survival but not graft survival. Older age and anti‐T‐cell antibodies may increase the risk of HBV reactivation, whereas lamivudine prophylaxis may prevent HBV reactivation after kidney transplantation.
A Simulation of the Unsteady Interaction of a Centrifugal Impeller With Its Vaned Diffuser: Flow Analysis
Authors: Dawes W. N.
Published: March 2013

The aim of this paper is to help advance our understanding of the complex, three-dimensional, unsteady flow associated with the interaction of a splittered centrifugal impeller and its vaned diffuser. A time-resolved simulation is presented of the Krain stage performed using a time-accurate, three-dimensional, unstructured mesh, solution-adaptive Navier–Stokes solver. The predicted flowfield, compared with experiment where available, displays a complex, unsteady interaction, especially in the neighborhood of the diffuser entry zone, which experiences large periodic flow unsteadiness. Downstream of the throat, although the magnitude of this unsteadiness diminishes rapidly, the flow has a highly distorted three-dimensional character. The loss levels in the diffuser are then investigated to try and determine how time-mean loss levels compare with the levels expected from “equivalent” steady flow analysis performed by using the circumferentially averaged exit flow from the impeller as inlet to the diffuser. It is concluded that little loss could be attributed directly to unsteady effects but rather that the principal cause of the rather high loss levels observed in the diffuser is the strong spanwise distortion in swirl angle at inlet, which initiates a strong hub/corner stall.
Prediction of Turbulent Flow and Heat Transfer in a Ribbed Rectangular Duct With and Without Rotation
Authors: Prakash C. , Zerkle R.
Published: March 2013

The present study deals with the numerical prediction of turbulent flow and heat transfer in a 2:1 aspect ratio rectangular duct with ribs on the two shorter sides. The ribs are of square cross section, staggered and aligned normal (90 deg) to the main flow direction. The ratio of rib height to duct hydraulic diameter equals 0.063, and the ratio of rib spacing to rib height equals 10. The duct may be stationary or rotating. The axis of rotation is normal to the axis of the duct and parallel to the ribbed walls (i.e., the ribbed walls form the leading and the trailing faces). The problem is three dimensional and fully elliptic; hence, for computational economy, the present analysis deals only with a periodically fully developed situation where the calculation domain is limited to the region between two adjacent ribs. Turbulence is modeled with the k–ε model in conjunction with wall functions. However, since the rib height is small, use of wall functions necessitates that the Reynolds number be kept high. (Attempts to use a two-layer model that permits integration to the wall did not yield satisfactory results and such modeling issues are discussed at length.) Computations are made here for Reynolds number in the range 30,000–100,000 and for Rotation number = 0 (stationary), 0.06, and 0.12. For the stationary case, the predicted heat transfer agrees well with the experimental correlations. Due to the Coriolis-induced secondary flow, rotation is found to enhance heat transfer from the trailing and the side walls, while decreasing heat transfer from the leading face. Relative to the corresponding stationary case, the effect of rotation is found to be less for a ribbed channel as compared to a smooth channel.
Heat Transfer Committee Best 1994 Paper Award: Experimental and Theoretical Investigations of Heat Transfer in Closed Gas-Filled Rotating Annuli II
Authors: Bohn D. , Emunds R. , Gorzelitz V. , Kru¨ger U.
Published: March 2013

Increasing the thermal efficiency by higher turbine inlet temperatures is one of the most important aims in the area of gas turbine development. Because of the high temperatures, the turbine vanes and blades have to be cooled, and also knowledge of the mechanically and thermally stressed parts in the hottest zones of the rotor is of great interest. The prediction of the temperature distribution in a gas turbine rotor containing closed, gas-filled cavities, for example, in between two disks, has to account for the heat transfer conditions encountered in these cavities. In an entirely closed annulus, forced convection is not present, but a strong natural convection flow exists, induced by a nonuniform density distribution in the centrifugal force field. In Bohn et al. (1994), experimental and numerical investigations on rotating cavities with pure centripetal heat flux had been carried out. The present paper deals with investigations on a pure axially directed heat flux. An experimental setup was designed to realize a wide range of Ra numbers (2·108< Ra < 5·1010) usually encountered in cavities of gas turbine rotors. Parallel to the experiments, numerical calculations have been conducted. The numerical results are compared with the experimental data. The numerical scheme is also used to account for the influence of Re on heat transfer without changing Ra. This influence could not be pointed out by experiments, because a variation of the Re–Ra characteristic of the employed annuli was not possible. It was found that the numerical and experimental data are in quite good agreement, with exception of high Ra, where the numerical scheme predicts higher heat transfer than the experiments show. One reason may be that in the experiments the inner and outer cylindrical walls were not really adiabatic, an assumption used in the numerical procedure. Moreover, the assumption of a two-dimensional flow pattern may become invalid for high Ra. The influence of three-dimensional effects was studied with the three-dimensional version of the numerical code. In contrast to the radial directed heat transfer, it was found that Nu is much smaller and depends strongly on Re, whereas the radial heat transfer is only weakly influenced by Re.
Impact of Rotor–Stator Interaction on Turbine Blade Film Cooling
Authors: Abhari R. S.
Published: March 2013

The goal of this study is to quantify the impact of rotor–stator interaction on surface heat transfer of film cooled turbine blades. In Section I, a steady-state injection model of the film cooling is incorporated into a two-dimensional, thin shear layer, multiblade row CFD code. This injection model accounts for the penetration and spreading of the coolant jet, as well as the entrainment of the boundary layer fluid by the coolant. The code is validated, in the steady state, by comparing its predictions to data from a blade tested in linear cascade. In Section II, time-resolved film cooled turbine rotor heat transfer measurements are compared with numerical predictions. Data were taken on a fully film cooled blade in a transonic, high pressure ratio, single-stage turbine in a short duration turbine test facility, which simulates full-engine nondimensional conditions. Film cooled heat flux on the pressure surface is predicted to be as much as a factor of two higher in the time average of the unsteady calculations compared to the steady-state case. Time-resolved film cooled heat transfer comparison of data to prediction at two spanwise positions is used to validate the numerical code. The unsteady stator–rotor interaction results in the pulsation of the coolant injection flow out of the film holes with large-scale fluctuations. The combination of pulsating coolant flow and the interaction of the coolant with this unsteady external flow is shown to lower the local pressure side adiabatic film effectiveness by as much as 64 percent when compared to the steady-state case.
Compressor Blade Forced Response Due to Downstream Vane-Strut Potential Interaction
Authors: Chiang H.-W. D. , Turner M. G.
Published: March 2013

A blade forced response prediction system has been developed using an implicit two-dimensional CFD solver to model the rotor blade forced response due to the static pressure distortion (potential disturbance) from the downstream stator vanes and struts. The CFD solver predicts the static pressure distortion upstream of the stator vanes and struts, which is used to calculate the induced velocity perturbation at the rotor inlet. Using the velocity perturbation and the blade’s natural frequencies and mode shapes from a finite element model, the unsteady aerodynamic modal forces and the aerodynamic damping are calculated. A modal response solution is then performed. The results show that the stator vanes cause a significant amplification of the potential disturbances due to the struts. Effects of strut and vane modifications are examined using the analysis. A vane modification with an “optimized” flow angle distribution shows that the disturbance can be greatly reduced. Recent testing of the strut modification shows exceptional correlation with the prediction.
Generalizing Circular Brush Seal Leakage Through a Randomly Distributed Bristle Bed
Authors: Chupp R. E. , Holle G. F.
Published: March 2013

Brush seals have established a niche in the gas-to-gas sealing against leakage in modern turbine engines. The variable nature of the brush during operation makes leakage prediction difficult. A simple semi-empirical model based on an effective brush thickness parameter has been successfully used to correlate and predict brush seal leakage in engine environments. The model was extended to correlate a range of brush densities using a physically realistic brush thickness. Later, the model was based on mean diametric brush properties for a large range of circular brush seal geometries. However, the best basis for modeling bristle, distribution was unknown. This paper proposes a solution to the distribution problem by assuming a randomly distributed bristle bed. A random distribution leads to a rectangular array model that is supported by the quality of leakage data generalization. Applying the resultant effective thickness parameter to predict brush seal performance in turbine engines is discussed.
Pressure Oscillations Occurring in a Centrifugal Compressor System With and Without Passive and Active Surge Control
Authors: Jungowski W. M. , Weiss M. H. , Price G. R.
Published: March 2013

A study of pressure oscillations occurring in small centrifugal compressor systems without a plenum is presented. Active and passive surge control were investigated theoretically and experimentally for systems with various inlet and discharge piping configurations. The determination of static and dynamic stability criteria was based on Greitzer’s (1981) lumped parameter model modified to accommodate capacitance of the piping. Experimentally, passive control using globe valves closely coupled to the compressor prevented the occurrence of surge even with the flow reduced to zero. Active control with a sleeve valve located at the compressor was effective but involved a significant component of passive throttling which reduced the compressor efficiency. With an oscillator connected to a short side branch at the compressor, effective active control was achieved without throttling. Both methods of active control reduced the flow rate at surge onset by about 30 percent. In general, the experiments qualitatively confirmed the derived stability criteria.
Improved Blade Profile Loss and Deviation Angle Models for Advanced Transonic Compressor Bladings: Part I—A Model for Subsonic Flow
Authors: Ko¨nig W. M. , Hennecke D. K. , Fottner L.
Published: March 2013

New blading concepts as used in modern transonic axial-flow compressors require improved loss and deviation angle correlations. The new model presented in this paper incorporates several elements and treats blade-row flows having subsonic and supersonic inlet conditions separately. In the first part of this paper two proved and well-established profile loss correlations for subsonic flows are extended to quasi-two-dimensional conditions and to custom-tailored blade designs. Instead of a deviation angle correlation, a simple method based on singularities is utilized. The comparison between the new model and a recently published model demonstrates the improved accuracy in prediction of cascade performance achieved by the new model.
Education Committee Best Paper of 1996 Award: Response of a Turbofan Engine Compression System to Disturbed Inlet Conditions
Authors: Abdel-Fattah A. M.
Published: March 2013

A generic code DYNTECC has been adapted to perform a parametric study of the effect of inlet flow distortion on the stability of the Pratt and Whitney TF30 engine. This code was developed at Arnold Engineering Development Center, USA, for single and dual spool systems. It was modified at AMRL to accommodate the particular geometry of the TF30 engine. The stage characteristics needed to operate DYNTECC were derived from experimental data for the fan and low-pressure compressor. For the high-pressure compressor they were derived using the STGSTK code developed at NASA Lewis Research Center. This program was modified at AMRL to include real flow effects that were in turn derived using yet another adapted code, CASCAD. The code was primarily used at AMRL to predict the onset of system instability due to simulated full-face rapid inlet temperature ramps typical of those caused during armament firings. It was also run with sinusoidal total pressure oscillations of varying amplitudes and frequencies at the inlet. The code predictions were compared with available data whenever possible, and were found to be consistent with the observed experimental trends.
A Linearized Unsteady Aerodynamic Analysis for Real Blade Supersonic Cascades
Authors: Montgomery M. D. , Verdon J. M. , Fleeter S.
Published: March 2013

The prediction capabilities of a linearized unsteady potential analysis have been extended to include supersonic cascades with subsonic axial flow. The numerical analysis of this type of flow presents several difficulties. First, complex oblique shock patterns exist within the cascade passage. Second, the acoustic response is discontinuous and propagates upstream and downstream of the blade row. Finally, a numerical scheme based on the domain of dependence is required for numerical stability. These difficulties are addressed by developing a discontinuity capturing scheme and matching the numerical near-field solution to an analytical far-field solution. Comparisons with semi-analytic results for flat plate cascades show that reasonable predictions of the unsteady aerodynamic response at the airfoil surfaces are possible, but aeroacoustic response calculations are difficult. Comparisons between flat plate and real blade cascade results show that one effect of real blades is the impulsive loads due to motion of finite strength shocks.
The Application of Actuator Disks to Calculations of the Flow in Turbofan Installations
Authors: Joo W. G. , Hynes T. P.
Published: March 2013

This paper discusses the application of an actuator disk model to the problem of calculating the asymmetric performance of a turbofan operating behind a nonaxisymmetric intake and due to the presence of the engine pylon. Good agreement between predictions and experimental results is demonstrated. Further validation of the model is obtained by comparison with the results of a three-dimensional calculation of an isolated fan operating with a nonaxisymmetric inlet. Some justification of the neglect of unsteady aspects of the flow in the fan is presented. The quantitative features of the interaction of the pylon and fan flow fields are discussed.
Investigation of the Heat-Island Effect for Heat-Flux Measurements in Short-Duration Facilities
Authors: Dunn M. G. , Kim J. , Rae W. J.
Published: March 2013

This paper presents the results of an experimental investigation designed to determine the possible influence of a surface-temperature discontinuity on the heat-flux history inferred from the temperature history of a miniature thin-film heat-flux gage (painted on an insulator) embedded in the surface of a metallic component. The resulting surface material discontinuity has the potential of causing a heat-island effect. Simultaneous measurements of the heat-flux history at selected locations along the midspan of a representative turbine airfoil (metal) were performed using continuous strip-type contoured inserts (without temperature discontinuity) and button-type inserts (with temperature discontinuity). Measurements are reported for two Reynolds number conditions. The experimental results suggest that for the experimental conditions of interest to gas turbine research in short-duration facilities, the influence of a potential heat-island on the measured heat flux is insignificant.
A Systematic Computational Methodology Applied to a Three-Dimensional Film-Cooling Flowfield
Authors: Walters D. K. , Leylek J. H.
Published: March 2013

Numerical results are presented for a three-dimensional discrete-jet in crossflow problem typical of a realistic film-cooling application in gas turbines. Key aspects of the study include: (1) application of a systematic computational methodology that stresses accurate computational model of the physical problem, including simultaneous, fully elliptic solution of the crossflow, film-hole, and plenum regions; high-quality three-dimensional unstructured grid generation techniques, which have yet to be documented for this class of problems; the use of a high-order discretization scheme to reduce numerical errors significantly; and effective turbulence modeling; (2) a three-way comparison of results to both code validation quality experimental data and a previously documented structured grid simulation; and (3) identification of sources of discrepancy between predicted and measured results, as well as recommendations to alleviate these discrepancies. Solutions were obtained with a multiblock, unstructured/adaptive grid, fully explicit, time-marching, Reynolds-averaged Navier–Stokes code with multigrid, local time stepping, and residual smoothing type acceleration techniques. The computational methodology was applied to the validation test case of a row of discrete jets on a flat plate with a streamwise injection angle of 35 deg, and two film-hole length-to-diameter ratios of 3.5 and 1.75. The density ratio for all cases was 2.0, blowing ratio was varied from 0.5 to 2.0, and free-stream turbulence intensity was 2 percent. The results demonstrate that the prescribed computational methodology yields consistently more accurate solutions for this class of problems than previous attempts published in the open literature. Sources of disagreement between measured and computed results have been identified, and recommendations made for future prediction of film-cooling problems.
The Effect of Vortex Shedding on the Unsteady Pressure Distribution Around the Trailing Edge of a Turbine Blade
Authors: Cicatelli G. , Sieverding C. H.
Published: March 2013

The wakes behind turbine blade trailing edges are characterized by large-scale periodic vortex patterns known as the von Karman vortex street. The failure of steady-state Navier–Stokes calculations in modeling wake flows appears to be mainly due to ignoring this type of flow instabilities. In an effort to contribute to a better understanding of the time-varying wake flow characteristics behind turbine blades, VKI has performed large-scale turbine cascade tests to obtain very detailed information about the steady and unsteady pressure distribution around the trailing edge of a nozzle guide vane. Tests are run at an outlet Mach number of M2,is, = 0.4 and a Reynolds number of ReC = 2 × 106. The key to the high spatial resolution of the pressure distribution around the trailing edge is a rotatable trailing edge with an embedded miniature pressure transducer underneath the surface and a pressure slot opening of about 1.5 deg of the trailing edge circle. Signal processing allowed differentiation between random and periodic pressure fluctuations. Ultrashort schlieren pictures help in understanding the physics behind the pressure distribution.
Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 1—Annular Groove
Authors: Rhode D. L. , Johnson J. W. , Broussard D. H.
Published: March 2013

An improved understanding of a new category of stepped labyrinth seals, which feature a new “annular groove,” was obtained. A water leakage and flow visualization test facility of very large scale (relative to a typical seal) was utilized. Flow visualization experiments using a new method and digital facilities for capturing and editing digital images from an 8 mm video were conducted. The presence of an annular groove machined into the stator land increases the leakage resistance by up to 26 percent for the cases considered here. Tracer particles show the degree of throughflow path penetration into the annular groove (i.e., serpentining), which gives the largest and the smallest leakage resistance improvement over that of the corresponding conventional stepped seal.
Flow Visualization and Leakage Measurements of Stepped Labyrinth Seals: Part 2—Sloping Surfaces
Authors: Rhode D. L. , Younger J. S. , Wernig M. D.
Published: March 2013

An experimental investigation was conducted to determine the geometry–leakage relationship for advanced, stepped labyrinth seals. A unique, variable-geometry water test facility was constructed and used to acquire leakage resistance measurements for two-dimensional, planar models. Flow visualization techniques were also used to assist in identifying and understanding the turbulence generating flow patterns. It was found that contoured surfaces and restrictor tooth leading-edge shapes of proper dimensions can be incorporated into the cavity geometry to reduce seal leakage. Specifically, the combination of a sloping surface and a curved surface on the rotor within the labyrinth cavity gave significant improvement.
Heuristic Optimization of Rough-Mill Yield With Production Priorities
Authors: Azarm S. , Harhalakis G. , Srinivasan M. , Statton P.
Published: March 2013

Efficient lumber utilization at the saw has become a key issue in the woodworking industry. This is because of shrinking supply and increasing raw materials prices. In this paper, formulation of the cross-cut first method of cutting defects out of lumber as a one-dimensional stock cutting problem is discussed. A Monte-Carlo simulation method has been used for generating boards of a given grade. This simulation greatly aids in comparing alternate solution procedures proposed in the paper. To facilitate real time-application, a fast heuristic for the digital computer is introduced. This is followed by a discussion of cutting length priority allocation. The heuristic solution is compared with the optimal solution obtained using Kolesar’s knapsack algorithm.
A General Optimization Model for Multi-Tool Manufacturing Systems
Authors: Billatos S. B. , Kendall L. A.
Published: March 2013

A machining center is a single numerically-controlled machine that incorporates several time-saving features and performs a multiplicity of operations. The life of cutting tools used in machining centers is modeled using probabilistic methods because of the stochastic nature and variability of tool-wear data. An approximate expression for the renewal function is used to establish an optimum scheduled tool replacement interval and an optimum set of cutting conditions to obtain a minimum production cost. A general optimization model for the multi-tool machining center is formulated considering practical machine constraints. Premature failure cost is not considered constant in this study. It is estimated using the tool cost, the expected cost of unplanned downtime, and the expended cost of product damage by premature tool failure. A user friendly computer program was developed to solicit information from a production engineer regarding cutting operations for the various tools used at the machining center. A sensitivity analysis on the results of the optimization process is presented.
Optimization Factors in Abrasive-Waterjet Machining
Authors: Hashish M.
Published: March 2013

This paper discusses the factors that need to be considered when selecting the operational parameters for abrasive-waterjet (AWJ) machining. Machining applications such as cutting, milling, and turning are considered along with sample data. The effects of different AWJ parameters on both the functional performance of the AWJ system components and the material removal process are discussed. Factors for optimizing these parameters include hardware limitations, high-pressure-related phenomena, and the performance interaction among the different nozzle components. Due to the large number of parameters and factors involved in AWJ machining processes, significant improvements in performance may be obtained by optimizing these parameters.
Temperature Distribution in a Hollow Cylindrical Workpiece During Machining: Theoretical Model and Experimental Results
Authors: Subramani G. , Whitmore M. C. , Kapoor S. G. , DeVor R. E.
Published: March 2013

In this paper, an analytical model is developed for computation of the temperature distribution in a hollow cylindrical workpiece during machining with a single point tool. Such a model is useful for prediction of machined surface error arising from thermal expansion of the workpiece during machining. The model considers the interface between the tool and the workpiece to be a helically moving volumetric heat source. The governing equation satisfied by the temperature field, along with the appropriate boundary and initial conditions, is solved using the method of integral transforms. The experimental test facility used for the conduct of experiments for measurement of the temperature response in a cylindrical workpiece, namely a cylinder bore, during machining is discussed. The results from tests conducted using a laser as a heat source to verify the analytical model for temperature field are then presented. Several cylinder boring tests have been conducted, and the results from these tests along with the analysis performed with the temperature data to calibrate the temperature model are then discussed. Comparisons between predicted and measured temperature response in a cylinder bore during machining show good agreement.
Process Mechanics of Vertical Roller Mill Comminution Grinding
Authors: West M. P.
Published: March 2013

A theory is presented which allows calculation of the mechanical forces during comminution grinding of coal and minerals in vertical roller mills.
Thermal Response of a Metallic Mold to Thermoelastic Interactions at Its Inner Boundary—System Approach
Authors: Attia M. H. , Osman M. O. M.
Published: March 2013

The system theory is used to analyze the thermoelastic interaction at the casting-mold interface and to develop a simplified model for the thermal response of the mold. It is revealed that due to the interaction at the interface, the surface layer at the inner boundary of the mold behaves thermally as an underdamped second-order system and not as an overdamped one. The latter would be the case if the thermoelastic interaction were neglected. This finding is verified experimentally, using molds of different materials and melts of different compositions. The effect of this thermoelastic interaction on the transient temperature field within the mold wall is demonstrated using a finite element model for a spherical mold of a uniform wall thickness.
Design of Ni-Ti-Cu Alloy Coil Spring
Authors: Tsuji K.
Published: March 2013

A new method of coil spring design applicable to Ni-Ti-Cu shape memory alloy was studied. Design values agreed well with measurements within the range of 2 K of operating temperature, thus justifying the design. The present design method is based on the characteristics of shear stress, shear strain, and phase transformation temperature as its principal data, and therefore is accurate and superior in that the design can accommodate material deterioration and that the operation temperature can be determined.
Stochastic Modeling and Analysis of Abrasive Flow Machining
Authors: Williams R. E. , Rajurkar K. P.
Published: March 2013

Finishing operations in the metal working industry represent a critical and expensive phase of the overall production process. A new process called Abrasive Flow Machining (AFM) promises to provide the accuracy, efficiency, economy, and the possibility of effective automation needed by the manufacturing community. The AFM process is still in its infancy in many respects. The process mechanism, parametric relationships, surface integrity, process control issues have not been effectively addressed. This paper presents preliminary results of an investigation into some aspects of the AFM process performance, surface characterization, and process modeling. The effect of process input parameters (such as media viscosity, extrusion pressure, and number of cycles) on the process performance parameters (metal removal rate and surface finish) are discussed. A stochastic modeling and analysis technique called Data Dependent Systems (DDS) has been used to study AFM generated surface. The Green’s function of the AFM surface profile models provides a “characteristic shape” that is the superimposition of two exponentials. The analysis of autocovariance of the surface profile data also indicates the presence of two real roots. The pseudo-frequencies associated with these two real roots have been linked to the path of the abrasive grains and to the cutting edges of the grain. Furthermore, expressions have been proposed for estimating the abrasive grain wear and the number of grains actively involved in cutting with a view towards developing indicators of media batch life. A brief introduction to the AFM process and related research is also included in this paper.
Sensor Synthesis for Control of Manufacturing Processes
Authors: Chryssolouris G. , Domroese M. , Beaulieu P.
Published: March 2013

When a human controls a manufacturing process he or she uses multiple senses to monitor the process. Similarly, one can consider a control approach where measurements of process variables are performed by several sensing devices which in turn feed their signals into process models. Each of these models contains mathematical expressions based on the physics of the process which relate the sensor signals to process state variables. The information provided by the process models should be synthesized in order to determine the best estimates for the state variables. In this paper two basic approaches to the synthesis of multiple sensor information are considered and compared. The first approach is to synthesize the state variable estimates determined by the different sensors and corresponding process models through a mechanism based on training such as a neural network. The second approach utilizes statistical criteria to estimate the best synthesized state variable estimate from the state variable estimates provided by the process models. As a “test bed” for studying the effectiveness of the above sensor synthesis approaches turning has been considered. The approaches are evaluated and compared for providing estimates of the state variable tool wear based on multiple sensor information. The robustness of each scheme with respect to noisy and inaccurate sensor information is investigated.
On the Dynamic Characteristics of Radial-Axial Ring Rolling Processes
Authors: Choi H. D. , Cho H. S. , Lee J. S.
Published: March 2013

An analytical model is presented to describe the dynamic characteristics of the radial-axial ring rolling process. Growing motions of rolled ring are analyzed in relation to the actions of pressure roll and conical roll, and the variations of both rolling forces are also discussed. In this developed model the interaction between pressure roll and conical roll motions as well as the temperature variation of rolled material which critically affects the deformed state of the ring is considered. To verify the validity of this dynamic model, the simulation results are compared with those obtained experimentally. Experiments were carried out with AISI 1045 steel blanks in hot condition. The theoretical results are found to coincide well with the experimental results.
A Review of Jet Assisted Rock Cutting
Authors: Hood M. , Knight G. C. , Thimons E. D.
Published: March 2013

High volume, low pressure water jets have been employed for erosion of loosely consolidated rocks for centuries and this excavation method finds application in specialized circumstances even today. The use of high pressure, low volume water jets for rock cutting is more recent and was made possible by the development of high pressure water pumps. This approach to rock breakage has been touted by an enthusiastic group of research workers, and we count ourselves among these workers, for at least the past two decades. Despite the benefits often claimed for these systems, high pressure water jets still have not found widespread application. In this paper we review the various methods that have been employed using waterjets to break rock and we focus on one method, termed jet assisted cutting, which, in our view is the closest to commercial development. We review the current state of knowledge based on laboratory and field experiences using this cutting method and we assess possible future developments for this approach to excavation.
CAE of Mold Cooling in Injection Molding Using a Three-Dimensional Numerical Simulation
Authors: Himasekhar K. , Lottey J. , Wang K. K.
Published: March 2013

In recent years, increased attention has been paid to the design of cooling systems in injection molding, as it became clear that cooling affects both productivity and part quality. In order to systematically improve the performance of a cooling system in terms of rapid, uniform, and even cooling, the designer needs a CAE analysis tool. For this, a computer simulation has been developed for three-dimensional mold heat transfer during the cooling stage of an injection molding process. In this simulation, mold heat transfer is considered as cyclic-steady, three-dimensional conduction; heat transfer within the melt region is treated as transient, one-dimensional conduction; heat exchange between the cooling channel surfaces and coolant is treated as steady, as is heat exchange with the ambient air and mold exterior surfaces. Numerical implementation includes the application of a hybrid scheme consisting of a modified three-dimensional, boundary-element method for the mold region and a finite-difference method with a variable mesh for the melt region. These two analyses are iteratively coupled so as to match the temperature and heat flux at the mold-melt interface. Using an example, the usefulness of the simulation developed here in the design of a cooling system for an injection molding process is amply demonstrated.
Processing of Cellular Polyurethane by Ultrasonic Excitation
Authors: Park H. , Youn J. R.
Published: March 2013

Processing of cellular polyurethane was investigated experimentally and theoretically to examine the possibility of ultrasonic foaming. Polyol resin was supersaturated with nitrogen and ultrasonic excitation was applied for copious bubble nucleation. The ultrasonic excitation resulted in good foam structure whose size distribution was uniform and less than 100 μm. The ultrasonic excitation was modelled by utilizing the classical nucleation theory to predict the rate of nucleation. Theoretical results suggest that a high rate of nucleation will be obtained if the ultrasonic excitation generates large enough negative pressure. Final bubble size was calculated by considering the pressure equilibrium between inside and outside of the bubble.
A Fiber-Optic Network Protocol for Computer Integrated Manufacturing
Authors: Ayyagari A. , Ray A.
Published: March 2013

This paper presents the architecture and performance analysis of a fiber-optic-based network protocol for computer integrated manufacturing (CIM). Its adaptation as the common medium access control (MAC) layer protocol in the fiber-optic-based version of the Manufacturing Automation Protocol (MAP) and Technical and Office Protocols (TOP) will make their specifications identical up to the presentation layer; only the application layer which is user specific could be different.