bluuebunny/crossref_metadata_2025 huggingface dataset:
Promoting Sleep by Nursing Interventions in Health Care Settings: A Systematic Review
Authors: Hellström Amanda , Willman Ania
Published: October 2010

Background:Sleep disturbances are common problems among individuals in hospitals and institutions. Although several studies have explored this phenomenon, there is still a lack of knowledge about the effectiveness of sleep‐promoting nursing interventions. This systematic review aims to describe and evaluate the effectiveness of sleep‐promoting nursing interventions in health care settings.

Approach:A systematic review was performed. In June 2009, a literature search was carried out in the following databases: Academic Search Elite, CINAHL, the Cochrane Library and MedLine/PubMed. Fifty‐two references were identified and after critical appraisal, nine studies were selected. A compilation of the results and the outcomes of the interventions were carried out. Furthermore, the evidence strength of the interventions was assessed.

Findings:Little evidence for the nursing interventions, sleep hygiene, music, natural sound and vision, stimulation of acupoints, relaxation, massage and aromatherapy is found. However, large effect size of interventions were found when using massage, acupuncture and music, natural sounds or music videos. The use of sleep hygiene and relaxation, on the other hand, produced only small effects.

Conclusion:The lack of high evidence strength for the nursing interventions together with the uncertainty about their effects calls for more research before implementing these interventions into clinical practice.
Coloplast Titan Inflatable Penile Prosthesis with One-Touch Release Pump: Review of 100 Cases and Comparison with Genesis Pump
Authors: Shaw Tavis , Garber Bruce B.
Published: October 2010

Introduction

In 2008 Coloplast Corporation modified their Titan inflatable penile prosthesis (IPP) with a new One-Touch Release (OTR) pump, in an attempt to facilitate device deflation. There is currently little published data concerning this new pump.

Aim

The aim of this pilot study was to assess initial patient and physician experience with the Titan OTR pump.

Methods

Retrospective chart review was used to assess the functionality and surgeon experience with 100 consecutive patients implanted with a Titan OTR pump, compared with 100 prior consecutive patients implanted with a Titan Genesis pump.

Main Outcome Measures

The ease of implantation of the OTR pump, the number of required postoperative inflate/deflate teaching visits, and OTR pump functionality were assessed and compared with that of the prior Genesis pump.

Results

The mean length of follow-up in the Genesis group (N = 100) was 20.8 months, and mean length of follow-up in the OTR group (N = 100) was 8.4 months. There was one device infection in each group. The average number of postoperative teaching sessions needed to teach the patient how to operate the device was 1.87 in the Genesis group, and 1.19 in the OTR group (P < 0.001). The range of teaching visits was 1–5 in the Genesis group, and 1–3 in the OTR group (P < 0.001). No pump malfunctions were seen in either group. Subjectively, the OTR pump was just as easy to implant as the Genesis pump. In addition, the OTR pump was subjectively easier for the surgeon and the patient to deflate, and just as easy to inflate, compared with the Genesis pump.

Conclusions

This pilot study revealed that the OTR pump functioned as specified by the manufacturer. With short-term follow-up, no pump malfunctions were detected. The OTR pump was associated with a statistically significant reduction in the number of postoperative teaching sessions required for the patient to properly operate the device. It was subjectively just as easy to implant and inflate, and easier to deflate, compared with the Genesis pump.
Assessing the Utility of Diagnostic Criteria: A Multisite Study on Gender Identity Disorder
Authors: Paap Muirne C.S. , Kreukels Baudewijntje P.C. , Cohen-Kettenis Peggy T. , Richter-Appelt Hertha , deCuypere Griet , Haraldsen Ira R.
Published: October 2010

Introduction

Studies involving patients with gender identity disorder (GID) are inconsistent with regard to outcomes and often difficult to compare because of the vague descriptions of the diagnostic process. A multisite study is needed to scrutinize the utility and generality of different aspects of the diagnostic criteria for GID.

Aim

To investigate the way in which the diagnosis-specific Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision criteria for GID were used to reach a psychiatric diagnosis in four European countries: the Netherlands (Amsterdam), Norway (Oslo), Germany (Hamburg), and Belgium (Ghent). The main goal was to compare item (symptom) characteristics across countries.

Methods

The current study included all new applicants to the four GID clinics who were seen between January 2007 and March 2009, were at least 16 years of age at their first visit, and had completed the diagnostic assessment (N = 214, mean age = 32 ± 12.2 years). Mokken scale analysis, a form of Nonparametric Item Response Theory (NIRT) was performed.

Main Outcome Measures

Operationalization and quantification of the core criteria A and B resulted in a 23-item score sheet that was filled out by the participating clinicians after they had made a diagnosis.

Results

We found that, when ordering the 23 items according to their means for each country separately, the rank ordering was similar among the four countries for 21 of the items. Furthermore, only one scale emerged, which combined criteria A and B when all data were analyzed together.

Conclusions

Our results indicate that patients’ symptoms were interpreted in a similar fashion in all four countries. However, we did not find support for the treatment of A and B as two separate criteria. We recommend the use of NIRT in future studies, especially in studies with small sample sizes and/or with data that show a poor fit to parametric IRT models.
HerMES: Herschel-SPIRE observations of Lyman break galaxies
Authors: Rigopoulou D. , Magdis G. , Ivison R. J. , Amblard A. , Arumugam V. , Aussel H. , Blain A. , Bock J. , Boselli A. , Buat V. , Burgarella D. , Castro-Rodríguez N. , Cava A. , Chanial P. , Clements D. L. , Conley A. , Conversi L. , Cooray A. , Dowell C. D. , Dwek E. , Eales S. , Elbaz D. , Farrah D. , Franceschini A. , Glenn J. , Griffin M. , Halpern M. , Hatziminaoglou E. , Huang J.-S. , Ibar E. , Isaak K. , Lagache G. , Levenson L. , Lu N. , Madden S. , Maffei B. , Mainetti G. , Marchetti L. , Nguyen H. T. , O’Halloran B. , Oliver S. J. , Omont A. , Page M. J. , Panuzzo P. , Papageorgiou A. , Pearson C. P. , Pérez-Fournon I. , Pohlen M. , Rizzo D. , Roseboom I. G. , Rowan-Robinson M. , Schulz B. , Scott Douglas , Seymour N. , Shupe D. L. , Smith A. J. , Stevens J. A. , Symeonidis M. , Trichas M. , Tugwell K. E. , Vaccari M. , Valtchanov I. , Vigroux L. , Wang L. , Wright G. , Xu C. K. , Zemcov M.
Published: October 2010

We present first results of a study of the submillimetre (submm) (rest-frame far-infrared) properties of z∼ 3 Lyman break galaxies (LBGs) and their lower redshift counterparts BX/BM galaxies, based on Herschel-SPIRE observations of the Northern field of the Great Observatories Origins Deep Survey (GOODS-N). We use stacking analysis to determine the properties of LBGs well below the current limit of the survey. Although LBGs are not detected individually, stacking the infrared luminous LBGs (those detected with Spitzer at 24 μm) yields a statistically significant submm detection with mean flux 〈S250〉= 5.9 ± 1.4 mJy confirming the power of SPIRE in detecting UV-selected high-redshift galaxies at submm wavelengths. In comparison, the Spitzer 24 μm detected BX/BM galaxies appear fainter with a stacked value of 〈S250〉= 2.7 ± 0.8 mJy. By fitting the spectral energy distributions (SEDs) we derive median infrared luminosities, LIR, of 2.8 × 1012 L⊙ and 1.5 × 1011 L⊙ for z∼ 3 LBGs and BX/BMs, respectively. We find that LIR estimates derived from present measurements are in good agreement with those based on UV data for z∼ 2 BX/BM galaxies, unlike the case for z∼ 3 infrared luminous LBGs where the UV underestimates the true LIR. Although sample selection effects may influence this result we suggest that differences in physical properties (such as morphologies, dust distribution and extent of star-forming regions) between z∼ 3 LBGs and z∼ 2 BX/BMs may also play a significant role.
Optical/IR counterpart to the resolved X-ray jet source CXO J172337.5−373442 and its distance
Authors: Mookerjea Bhaswati , Parisi Pietro , Bhattacharyya Sudip , Masetti Nicola , Krühler Thomas , Greiner Jochen
Published: October 2010

We present results of observations in the optical to mid-infrared wavelengths of the X-ray source CXO J172337.5–373442, which was serendipitously discovered in the Chandra images and was found to have a fully resolved X-ray jet. The observations include a combination of photometry and spectroscopy in the optical using ground-based telescopes and mid-infrared photometry using Spitzer. We detect the optical/IR counterpart of CXO J172337.5–373442 and identify it to be a G9 V star located at a distance of 334 ± 60 pc. Comparable values of the hydrogen column densities determined independently from the optical/IR observations and X-ray observations indicate that the optical source is associated with the X-ray source. Since the X-ray luminosity cannot be explained in terms of emission from a single G9 V star, it is likely that CXO J172337.5–373442 is an accreting compact object in a binary system. Thus, CXO J172337.5–373442 is the nearest known resolved X-ray jet from a binary system, which is not a symbiotic star. Based on the existing X-ray data, the nature of the compact object cannot be confirmed. However, the low luminosity of the X-ray point source, 7.1 × 1030 L⊙, combined with estimates of the age of the jet and a lack of detection of bright outburst, suggests that the X-ray jet was launched during extreme quiescence of the object. The measured low X-ray luminosity of the jet suggests the likelihood of such jets being more ubiquitous than our current understanding.
Identification of Candidate Amino Acids Involved in the Formation of Pink‐Red Pigments in Onion (Allium cepa L.) Juice and Separation by HPLC
Authors: Lee Eun Jin , Yoo Kil Sun , Patil Bhimanagouda S.
Published: October 2010

Abstract:  The formation of pink‐red pigments (“pinking”) by various amino acids was investigated by reacting amino acids with compounds present in onion juice. The unknown pink‐red pigments were generated and separated using high‐performance liquid chromatography (HPLC) and a diode array detector (DAD) in the range of 200 to 700 nm. To generate pink‐red pigments, we developed several reaction systems using garlic alliinase, purified 1‐propenyl‐L‐cysteine sulfoxide (1‐PeCSO), onion thiosulfinate, natural onion juice, and 21 free amino acids. The compound 1‐PeCSO was a key compound associated with pinking in the presence of both the alliinase and amino acids. Numerous naturally occurring pink‐red pigments were detected and separated from pink onion juice using the HPLC‐DAD system at 515 nm. Most free amino acids, with the exceptions of histidine, serine, and cysteine, formed various pink‐red pigments when reacted with onion thiosulfinate. This observation indicated that onion pinking is caused not by a single pigment, but by many. Furthermore, more than one color compound could be produced from a single amino acid; this explains, in part, why there were many pink‐red compound peaks in the chromatogram of discolored natural onion juice. We presumed that the complexity of the pink‐red pigments was due to the involvement of more than 21 natural amino acids as well as several derivatives of the color products produced from each amino acid. We observed that the pinking process in onion juice is very similar to that of the greening process in crushed garlic, emphasizing that both thiosulfinate from flavor precursors and free amino acids are absolutely required for the discoloration.
Properties of Bread Dough with Added Fiber Polysaccharides and Phenolic Antioxidants: A Review
Authors: Sivam Anusooya S. , Sun‐Waterhouse Dongxiao , Quek SiewYoung , Perera Conrad O.
Published: October 2010

Abstract:  During breadmaking, different ingredients are used to ensure the development of a continuous protein network that is essential for bread quality. Interests in incorporating bioactive ingredients such as dietary fiber (DF) and phenolic antioxidants into popular foods such as bread have grown rapidly, due to the increased consumer health awareness. The added bioactive ingredients may or may not promote the protein cross‐links. Appropriate cross‐links among wheat proteins, fiber polysaccharides, and phenolic antioxidants could be the most critical factor for bread dough enhanced with DF and phenolic antioxidants. Such cross‐links may influence the structure and properties of a bread system during baking. This article presents a brief overview of our current knowledge of the fate of the key components (wheat proteins, fibers, and phenolic antioxidants) and how they might interact during bread dough development and baking.
Use of Tuf Gene‐Based Primers for the PCR Detection of Probiotic Bifidobacterium Species and Enumeration of Bifidobacteria in Fermented Milk by Cultural and Quantitative Real‐Time PCR Methods
Authors: Sheu Sen‐Je , Hwang Wen‐Zhe , Chiang Yu‐Cheng , Lin Wen‐Hsin , Chen Hsin‐Chih , Tsen Hau‐Yang
Published: October 2010

Abstract:  Due to the increasing use of bifidobacteria in probiotic products, it is essential to establish a rapid method for the qualitative and quantitative assay of the bifidobacteria in commercial products. In this study, partial sequences of the tuf gene for 18 Bifidobacterium strains belonging to 14 species were determined. Alignment of these sequences showed that the similarities among these Bifidobacterium species were 82.24% to 99.72%. Based on these tuf gene sequences, 6 primer sets were designed for the polymerase chain reaction (PCR) assay of B. animalis subsp. animalis, B. animalis subsp. lactis, B. bifidum, B. breve, B. longum subsp. infantis, B. longum subsp. longum, and the genus of Bifidobacterium, respectively. These Bifidobacterium species are common probiotic species present in dairy and probiotic products. When each target Bifidobacterium spp. was assayed with the designed primers, PCR product with expected size was generated. In addition, for each target species, more than 70 bacterial strains other than the target species, including strains of other Bifidobacterium species, strains of Lactobacillus spp., Enterococcus spp., and other bacterial species, all generated negative results. PCR assay with primers specific to B. animalis subsp. lactis and B. longum subsp. longum confirmed the presence of these Bifidobacterium species in commercial yogurt products. In addition, for each product, enumeration of the bifidobacteria cells by culture method with BIM‐25 agar and the quantitative real‐time PCR showed similar cell counts. Such results indicated that within 15‐d storage (4 °C) after manufacture, all the bifidobacteria cells originally present in yogurt products were viable and culturable during the storage.
Advances in endoscopic diagnosis and treatment of Barrett's esophagus
Authors: GADDAM Srinivas , SHARMA Prateek
Published: October 2010

Barrett's esophagus (BE) is defined as abnormal specialized columnar metaplasia with intestinalization in place of the normal squamous esophageal epithelium. Gastroesophageal reflux disease is a known risk factor for BE; nonetheless BE is also detected in asymptomatic individuals. Other risk factors for BE include smoking, male gender, age over 50 and obesity. Patients diagnosed with BE (without dysplasia) are recommended to undergo endoscopic surveillance every 3–5 years. Advances in imaging techniques (such as narrow band imaging, autofluorescence imaging and confocal laser endomicroscopy) have the potential to improve the detection of dysplasia and early cancer, thus making surveillance a more cost‐effective endeavor. Patients with high grade dysplasia (HGD) and early cancer have a high rate of progression to invasive adenocarcinoma and traditionally these patients were treated with esophagectomy. The rapid advancement of endoscopic therapeutic techniques along with a low risk of complications have made endoscopic therapy an acceptable alternative to an esophagectomy in patients with HGD and early cancer. Several endoscopic treatment techniques such as endoscopic mucosal resection, multipolar electrocoagulation, photodynamic therapy, argon plasma coagulation, cryotherapy, and radiofrequency ablation have been studied for endoscopic treatment.
Hybridization effects on phenotypic plasticity: experimental compensatory growth in farmed‐wild Atlantic salmon
Authors: Morris Matthew R. J. , Fraser Dylan J. , Eddington James , Hutchings Jeffrey A.
Published: October 2010

Compensatory growth (CG) is a means by which organisms can increase their growth rate above their routine growth rate after a period of environmentally induced growth depression. Despite a focus on the implications of CG for aquaculture, little research has evaluated the effect of domesticated–wild hybridization on CG. Any deviation in the mean compensatory ability of hybrids relative to their wild progenitors, or any notable costs to compensation in terms of body morphology, could affect the ability of hybrids to persist in changing environments. We compared CG of farmed, wild and hybrid (F1, F2, wild backcross) juvenile Atlantic salmon (Salmo salar). Wild salmon experienced both lower routine and CG rates relative to farmed salmon, while hybrids were intermediate. However, the compensatory responses (slopes of the reaction norms) for each cross were parallel, indicating that hybridization did not affect the CG response itself. Morphological costs to compensation were not detected. In addition to contributing to risk assessments of the consequences of interbreeding between wild and escaped domesticated organisms, we conclude that plasticity studies on domesticated–wild hybrids and their progenitors are useful for testing basic predictions about the evolution of phenotypic plasticity, as well as understanding the evolutionary significance of hybrids.
Malignant pleural mesothelioma: A retrospective analysis of clinicopathological and survival data
Authors: Adel Azza M. , Abdel Hafeez Zeinab M. , El Sheikh Eman T. , El Sharawy Iman A. , Gobran Nagy S.
Published: October 2010

Background: The aim of this study was to analyze the clinicopathological features of malignant pleural mesothelioma (MPM) and evaluate the therapeutic measures offered to patients with MPM and their impact on survival.

Methods: Data was retrospectively collected from the medical records of 304 patients who presented to the Department of Clinical Oncology and Nuclear Medicine, Ain Shams University between January 2003 and December 2008.

Results: The mean age of patients was 52.1 years (range 24–87 years). One hundred and ninety patients (62.5%) came from endemic areas and/or gave history of occupational asbestos exposure. One hundred and sixty‐nine patients received chemotherapy. There was a significant difference between the median survival for patients who received chemotherapy (9 months, 95% CI 7.69–10.30) and those who were offered best supportive care (2 months, 95% CI 0.09–3.91). Other factors that affected the survival negatively were: non‐epithelial pathology (P= 0.001); age >50 years (P= 0.012); bad performance status (P= 0.001); non‐platinum based chemotherapy (P= 0.0001); and progressive disease (P= 0.000). Cox regression analysis revealed that the factors that predicted shorter survival were patients being offered best supportive care rather than chemotherapy and progressive disease.

Conclusion: MPM is a growing health problem in Egypt that needs more attention. The current analysis of data reflects the importance of maintaining a high index of suspicion to allow for early diagnosis, especially for cases that live in areas with high asbestos exposure and for people who work in occupations that expose them to asbestos as well as their family members. Prospective randomized trials comparing multimodality approaches to other forms of treatment and including quality of life assessment are warranted.
Push or Pull? Auctioning Supply Contracts
Authors: Li Cuihong , Scheller‐Wolf Alan
Published: October 2010

Consider a buyer, facing uncertain demand, who sources from multiple suppliers via online procurement auctions (open descending price‐only auctions). The suppliers have heterogeneous production costs, which are private information, and the winning supplier has to invest in production capacity before the demand uncertainty is resolved. The buyer chooses to offer a push or pull contract, for which the single price and winning supplier are determined via the auction. We show that, with a pull contract, the buyer does not necessarily benefit from a larger number of suppliers participating in the auction, due to the negative effect of supplier competition on the incentive of supplier capacity investment. We thus propose an enhanced pull mechanism that mitigates this effect with a floor price. We then analyze and compare the outcomes of auctions for push and (enhanced) pull contracts, establishing when one form is preferred over the other based on the buyer's profits. We also compare our simple, price‐only push and pull contract auctions to the optimal mechanisms, benchmarking the performance of the simple mechanisms as well as establishing the relative importance of auction design and contract design in procurement auctions.
An Exploratory Study of Procurement Strategies for Multi‐Item RFQs in B2B Markets: Antecedents and Impact on Performance
Authors: Schoenherr Tobias , Mabert Vincent A.
Published: October 2010

This research explores procurement strategies for multi‐item requests for quotation (RFQs) in business‐to‐business (B2B) markets using responses from 825 purchasing professionals. The study first establishes procurement strategies that differ based on their level of strategic emphasis, i.e., the importance that is placed on the pursuit of four strategic objectives. Underlying objectives, which are obtained via factor analysis, include the focus on price, security of supply, internal procurement efficiencies, and bundle building. Next, cluster analysis is used to derive prototypical strategic approaches. The three cluster groups that emerge possess the same relative ranking of the four objectives, but differ based on the intensity with which these objectives are pursued. The clusters are labelled as the three strategic groups of strategists, opportunists, and responders. The research then explores, using an industrial buyer behavior lens, the impact of environmental antecedents in determining a particular strategy. Environmental variables include purchase importance, market uncertainty, supply base availability, buyer bargaining power, item experience, and supply base experience. Finally, the study tests the impact of procurement strategy on the buyer's perceived performance, suggesting that strategists, placing more emphasis on the pursuit of strategic sourcing objectives, achieve better performance than opportunists and responders.
Echocardiographic Changes in Heart Size in Hypohydrated Horses
Authors: Underwood C. , Norton J.L. , Nolen‐Walston R.D. , Dallap‐Schaer B.L. , Boston R. , Slack J.
Published: October 2010

Background:Hypohydration causes transient echocardiographic changes in pigs, dogs, humans, and cats. These changes mask the diagnosis of some cardiac diseases (valvular regurgitation, dilated cardiomyopathy) and promote the diagnosis of others (hypertropic cardiomyopathy and infiltrative disease), thus inhibiting accurate echocardiographic evaluation.

Objectives:To describe the echocardiographic changes associated with hypohydration in normal horses.

Animals:Ten adult horses without detectable cardiac disease.

Methods:Experimental study. Echocardiographic examinations were performed on horses in the euhydrated and hypohydrated states. Horses were hypohydrated by combined water deprivation and furosemide administration until a 4–7% reduction in bodyweight was achieved. Statistical analyses were performed by pairedt‐tests.

Results:Hypohydration decreased left ventricular internal diameter in systole (0.8 ± 0.6 cm) and diastole (1.7 ± 0.9 cm), left atrial diameter (1.5 ± 0.4 cm) and left ventricular volume (490 ± 251 mL) (P‐values < .01), and increased septal wall thickness in diastole (0.6 ± 0.3 cm), free wall thickness in diastole (0.5 ± 0.3 cm), mean wall thickness (0.5 ± 0.2 cm) and relative wall thickness (0.2 ± 0.1 cm) (P‐values < .01).

Conclusions and Clinical Importance:Hypohydration produces changes in left ventricular and atrial size that could mask or promote the severity of cardiac disease. The thickened, “pseudohypertrophied” appearance of the left ventricle in hypohydrated horses could affect interpretation of echocardiographic variables that are applied to the prediction of athletic performance. Echocardiography may prove a noninvasive method of monitoring volume status and response to fluid therapy in hypovolemic horses.
The Calibration of Preston Tubes in Transpired Turbulent Boundary Layers
Authors: Depooter K. , Brundrett E. , Strong A. B.
Published: October 2010

The Preston tube calibration of Patel is reproduced for zero pressure gradient and zero mass transfer turbulent flows, by momentum balance and by direct measurement using a floating element with mass transfer capability. The calibration is then extended to blowing and suction conditions, from near blow-off through to relaminarization. The effects of mass transfer are found to be moderate until conditions are encountered approaching relaminarization or blow-off. Transpiration effects are adequately correlated by a transpiration parameter proposed by Baker et al. As either the blow-off or suction relaminarization condition is approached, it is recommended that three or more sizes of Preston tubes be used which satisfy Patel’s middle range criterion. As suction relaminarization is approached the smallest tubes will show progressively greater departure from the wall similarity correlation. If a unique value of shear stress is obtained yet from the larger tubes it is valid. A similar test for consistency is recommended for conditions near blow-off. The study is extended to a boundary layer fence, which shows no significant mass transfer effect upon the zero transpiration calibration.
Approximate Numerical Solutions for Two-Dimensional Potential Flow Problems
Authors: Kieda A. , Yano H.
Published: October 2010

An approximate numerical method is proposed for solving two-dimensional potential flow problems. The method is included in the general class of “Method of Weighted Residuals.” Typical computed results are presented for the surface pressure distributions on an airfoil and single noncircular cylinders immersed in a uniform infinite stream.
Turbulence Measurements in Boundary Layers Along Mildly Curved Surfaces
Authors: Shivaprasad B. G. , Ramaprian B. R.
Published: October 2010

This paper presents results of turbulence measurements in boundary layers over surfaces of mild longitudinal curvature. The study indicates that convex wall curvature decreases both the length and velocity scales of turbulent motions, whereas concave curvature has the opposite effect. White being qualitatively similar to those brought about by stronger wall curvature, mild curvature effects are found to be much larger than what one expects from a linear interpolation between the effects of zero and strong curvature. It is also observed that curvature has a relatively larger effect on the Reynolds shear stress than on the turbulent kinetic energy. The present study, however, indicates that it is still possible to use some of the phenomenological models of turbulence (e.g., the mixing length model, the Prandtl-Kolmogorov model), provided an appropriate curvature model is available for describing the effect of curvature on the relevant length scale in the boundary layer. The present data are used to test the validity and limitations of such a curvature model (based on an analogy between streamline curvature and buoyancy) currently in use.
Developing Region of Laminar Jets With Uniform Exit Velocity Profiles
Authors: Rankin G. W. , Sridhar K.
Published: October 2010

The integral form of the momentum and energy equations, subject to the boundary layer simplifications, are used to obtain an approximate solution for an axisymmetric laminar jet with a uniform profile at the nozzle exit. The solution is expressed in a closed form. The jet flow field is divided into a developing and developed region. In the developing region a potential core is assumed to exist, bounded by an annular free shear layer, Schlichting’s velocity profile for an axisymmetric laminar jet is assumed in the free shear layer. The present solution is compared with existing experimental and analytical results in the developing region. Also a graphical method for determining the potential core radius and the parameters of the assumed Schlichting profile is given.
Fluid Dynamic Excitation of Centrifugal Compressor Rotor Vibrations
Authors: Thompson W. E.
Published: October 2010

A mechanism by which compressor rotor lateral vibration perturbs the mass flow-rate, the velocity and the pressure distributions within impeller passages is postulated. Such a perturbation will develop an unbalanced force on the rotor which, if it enhances the rotor vibration, is termed self-exciting. The concepts of rotor orbital velocity, the virtual center of shaft rotation, the reduction of unsteady flow to quasi-steady flow, the fluid dynamic force coefficient, mechanical orbital stability and the stability increment are introduced. The ideas are imposed on the streamline curvature method of quasi-three dimensional analysis of passage flow and a computer program has been assembled to carry out computation. No generalized guidelines have been found as yet but rather individual passage calculations are needed to determine the potentially exciting or damping character of the induced fluid dynamic forces. The average stability increment per stage for nine industrial multistage centrifugal compressors has been determined and compared with known operating experience. Important engineering characteristics of two of the compressors are shown in an example of the analysis. A provisional limit of the stability increment per stage ⩽ 1.85 lbf-s/in. (323.9N-s/m) is suggested, below which unstable nonsynchronous vibration of the compressor rotor can be expected.
On Vortex Wind Power
Authors: So Ronald M. C.
Published: October 2010

An infinite viscous laminar vortex with no reverse flow region in the exit plane, but with axial inflow at the base, is analyzed. The axial inflow is assumed to be finite everywhere. From the analysis, the maximum wind power that can be obtained from such a vortex is calculated. The results show that the power developed depends on the circulation at infinity and on the viscous radius of the core of the vortex. The significance of this result, as it relates to the recently proposed vortex wind energy system, is discussed.
A Design Method on Propeller Current Meters
Authors: Takeda Rikiya
Published: October 2010

A rational design method on propeller current meters that has a wide range of application to various fluids such as air, water, and oil is described. First, the runner characteristics were analyzed using the previously derived basic equations [6]. Next, many sorts of runners were tested in streams, such as the water tunnel, the oil tunnel, the wind tunnel, and the lowing tank. From these results, a general meter calibration formula, which is applicable to various fluids, was derived. If we use the basic equations, the characteristic equations and this calibration formula as the fundamental equations of the meter design, we can design current meter runners applicable to various fluids.
Frictional Moment of Flow Between Two Concentric Spheres, One of Which Rotates
Authors: Nakabayashi K.
Published: October 2010

Frictional moment is investigated experimentally for the flow between a rotating inner sphere and a stationary outer one, and for the flow between a rotating outer sphere and a stationary inner one, respectively. The existence of four basic flow regimes for both is verified, and their extent is mapped over a range of Reynolds number-clearance ratio combinations. An empirical formula for the coefficient of frictional moment is obtained for every flow regime. The coefficient of frictional moment obtained for spherical annulus flow is then correlated with that of the flow around a disk rotating in a confined space, and the effect of the surface curvature of rotating bodies is considered.
Review—Self-Sustaining Oscillations of Flow Past Cavities
Authors: Rockwell D. , Naudascher E.
Published: October 2010

Unstable flow past cavities is grouped into fluid-dynamic, fluid-resonant, and fluid-elastic categories. Fluid-dynamic oscillations are attributable to instability of the cavity shear layer and are enhanced through a feedback mechanism. Fluid-resonant oscillations are governed by resonance conditions associated with compressibility or freesurface wave phenomena. Fluid-elastic oscillations are primarily controlled by the elastic displacements of a solid boundary. Experimental information and theoretical models for the frequencies and amplitudes of each of these categories of oscillations as well as a combination of them are discussed in detail. Effects of arrangements of cavities in groups and variations in cavity shape (rectangular, circular, triangular, whistle-type, Helmholtz-type) are reviewed. Means of attenuation of oscillations via geometrical modifications and mass addition are summarized. Finally, the effects of cavity oscillations on the time-mean cavity pressure, drag, and shear-layer characteristics are discussed.
A Correlation for Laminar Hydrodynamic Entry Length Solutions for Circular and Noncircular Ducts
Authors: Shah R. K.
Published: October 2010

Laminar hydrodynamic entry length solutions for circular and noncircular ducts are essential in proper design of compact heat exchangers and other heat transfer and fluid flow devices. A closed form equation has been proposed to present these solutions for the circular tube, parallel plates, rectangular, equilateral triangular, and concentric annular ducts. The necessary constants are evaluated and it is shown that the proposed correlation predicts the apparent friction factors within ± 2.4 percent.
The Dynamics of Thin Liquid Films in Rotating Tubes: Approximate Analysis
Authors: Dakin J. T. , So Ronald M. C.
Published: October 2010

The dynamics of a thin liquid film flowing through a pipe rotating about an axis perpendicular to the pipe axis are studied. Static pressure is assumed constant along the pipe and the axial flow of the film is a direct consequence of the pull of the centrifugal force. The film is pushed to one side of the pipe by a Coriolis force which is nonconservative. As a result, a secondary motion is set up in the plane normal to the pipe axis. An approximate set of equations governing the secondary flow is analyzed through an integral technique for the case of a laminar film dominated by viscous effects. A visualization experiment is carried out and the approximate theory is found to compare favorably with the qualitative observations.
Laminar Throughflow of Varying-Quality Steam Between Corotating Disks
Authors: Truman C. R. , Rice W. , Jankowski D. F.
Published: October 2010

A local analysis was made of the laminar throughflow between corotating disks of a Newtonian vapor containing liquid droplets. Such a flow is of practical interest in multiple-disk turbomachinery, and specifically is a model of a two-phase, single component flow (saturated vapor - saturated liquid steam) which would arise in geothermal applications of a multiple-disk turbine. Local mass conservation and momentum equations for the vapor and droplet fields were used, as well as mass conservation and energy equations for a single droplet. The vapor-droplet interaction was modeled by a drag force based on the well-known drag coefficients for flow past spheres. The governing equations were reduced to parabolic form by order-of-magnitude arguments to allow a marching-type solution. The nonlinear partial differential equations were replaced by nonlinear finite-difference equations, which were linearized. The resulting system of linear algebraic equations was solved directly. Various results are presented, including results for a set of flow parameters which are close to those applicable for multiple-disk turbines operating on geothermal steam.
Liquid Jet Impingement Normal to a Disk in Zero Gravity
Authors: Labus T. L. , DeWitt K. J.
Published: October 2010

An experimental and analytical investigation was conducted to determine the free surface shapes of circular jets impinging normal to sharp-edged disks in zero gravity. Experiments conducted in a zero gravity drop tower yielded three distinct flow patterns which were classified in terms of the relative effects of surface tension and inertial forces. An order of magnitude analysis was conducted indicating regions where viscous forces were not significant when computing free surface shapes. The free surface analysis was simplified by transforming the governing potential flow equations and boundary conditions into the inverse plane. The resulting nonlinear equations were solved numerically and comparisons were made with the experimental data for the inertia dominated regime.
The Effect of Taylor Vortex Flow on the Radial Forces in an Annulus Having Variable Eccentricity and Axial Flow
Authors: Coney J. E. R. , Atkinson J.
Published: October 2010

Results are presented in dimensionless form as obtained in an experimental study of the resultant radial force variation in an eccentric annulus formed by a stationary outer cylinder and a rotating inner cylinder, through which an axial flow of oil may be pumped. Two eccentricity ratios, 0.5 and 0.9, and three axial Reynolds numbers for the flow of the fluid in the annulus, 0, 25, and 50, are considered. It is shown that the onset of Taylor vortex flow has a marked effect on the magnitude and direction of the resultant radial force. The resultant forces and attitude angles are compared with those derived from Sommerfeld’s journal bearing theory. Comparisons are also made between critical Taylor numbers for the present investigation and those available in the literature.
Turbulence Measurements in a Separated and Reattached Flow Over a Blunt Flat Plate
Authors: Ota Terukazu , Narita Masashi
Published: October 2010

Turbulence measurements were made in the separated, reattached, and redeveloped regions of a two-dimensional incompressible air flow over a flat plate with finite thickness and blunt leading edge. In the boundary layer downstream of the reattachment point, Prandtl’s mixing length and turbulent kinetic energy length scale are estimated, and the correlation between the turbulent shear stress and the turbulent kinetic energy is described.
A Yaw-Insensitive Static Pressure Probe
Authors: Huey L. J.
Published: October 2010

This paper reviews the development and testing of a static pressure probe which is relatively insensitive to yaw angle. The probe averages the pressure along an equatorial line on a sphere immersed in a flowing fluid such that the average measured pressure is the static pressure. The probe can be rotated up to ± 30 deg from the velocity vector with little error in the static pressure reading.
The Flapwing, A Unique Fluid Machine Element
Authors: Gerharz Reinhold
Published: October 2010

A flow engine element is described which converts the oscillations of a flapwing, that is mounted on a crankshaft, into rotary energy. A self-starting twin model of this energy flux converter was built and tested in a moderate stream of air. Driving this device with a motor reverses it into an air blower of the hydropulser class.
Laminar-Turbulent Flow in a Spherical Annulus
Authors: Waked A. M. , Munson B. R.
Published: October 2010

Experimental results are presented regarding the nature of the flow of a viscous incompressible fluid contained between two concentric spherical surfaces that rotate at different angular velocities. Depending upon the various parameters involved (the radius ratio, the angular velocity ratio, and the Reynolds number), the resulting flow in the spherical annulus may be laminar, turbulent, or some combination of laminar and turbulent flow. The basic laminar flow patterns are observed by use of flow visualization methods. Similarities and differences between the stability characteristics of spherical annulus flow and cylindrical annulus flow are discussed.
The Velocity Characteristics of Ventilated Rooms
Authors: Nielsen P. V. , Restivo A. , Whitelaw J. H.
Published: October 2010

Measured and calculated values of the velocity characteristics of a modeled room with ventilation arrangements are reported. The measurements were obtained by laser-Doppler anemometry and the calculations by the solution, in finite-difference form, of two-dimensional, elliptic, partial-differential equations representing conservation of mass, momentum, turbulence energy and dissipation rate. The results demonstrate that the precision of calculation is adequate for design purposes although, for slots much smaller than the width of the room, three-dimensional effects become important. They quantify, for example, the extent to which a decrease in supply area leads to an increase in air velocities for a given mass flow rate.
Loss Characteristics of Orifices and Nozzles
Authors: Alvi S. H. , Sridharan K. , Lakshmana Rao N. S.
Published: October 2010

Loss characteristics of sharp-edged orifices, quadrant-edged orifices for varying edge radii, and nozzles are studied for Reynolds numbers less than 10,000 for β ratios from 0.2 to 0.8. The results may be reliably extrapolated to higher Reynolds numbers. Presentation of losses as a percentage of meter pressure differential shows that the flow can be identified into fully laminar regime, critical Reynolds number regime, relaminarization regime, and turbulent flow regime. An integrated picture of variation of parameters such as discharge coefficient, loss coefficient, settling length, pressure recovery length, and center line velocity confirms this classification.
On the Growth of Steam Droplets Formed in a Laval Nozzle Using Both Static Pressure and Light Scattering Measurements
Authors: Moses C. A. , Stein G. D.
Published: October 2010

A series of experiments on steam condensation have been made in a Laval nozzle over a variety of starting conditions such that the onset of condensation occurs in the range −40 to 40°C (233–313 K). The homogeneous nucleation and growth of the new phase are documented with both static pressure and laser light scattering. Since even at onset the majority of the condensed phase is due to droplet growth the nucleation and growth are coupled and the availability of two measured quantities is helpful in comparing a particular combination of nucleation rate and growth law. For detailed calculations on one of the experiments there is excellent agreement with both measurements throughout the condensation zone and theoretical calculations using the classical nucleation rate expression due to Volmer and droplet growth laws due to Gyarmathy and Hill in which thermal and mass accommodation coefficients are near unity.
Cold Flow Tests of a Bluff-Body Flame Stabilizer
Authors: Fujii S. , Gomi M. , Eguchi K.
Published: October 2010

The aerodynamic characteristics of separated, recirculating flows behind a two-dimensional nozzle and bluff-body combination, which modeled a lean mixture combustor, was explored by a series of cold flow tests. The detailed distributions of mean velocities, static pressures, turbulent characteristics, and the tracer gas steady-state concentration were obtained. The flow velocity observations were successfully obtained by use of a laser velocimeter, whose data reduction system was devised particularly for use in highly turbulent flow measurements. Overall features of the mean field data revealed that the nozzle blowing diminished the longitudinal extent of the recirculation zone and substantially affected the mixing of tracer gas with the surrounding airflow. The Reynolds stress data imply that a zone of opposing shear was formed near the region of coexistence between negative and positive mean axial-velocities.
A Novel Physico-Computational Model for Quasi One-Dimensional Gas-Particle Flows
Authors: Sharma M. P. , Crowe C. T.
Published: October 2010

The analysis of gas-particle flows is complicated by the need to account for momentum and energy coupling between phases. The concept of regarding the particle phase as a source of momentum and energy to the gaseous phase is described and incorporated into a new computational scheme developed using conservative variables. Flow metering of gas-particle suspensions by a Venturi is analyzed to illustrate the applicability of this physico-computational model. The predicted pressure drop at the throat of the Venturi shows agreement with experimental data, establishing the capability of the model to treat the complex coupling phenomena in a physically appealing way through a convenient computational algorithm.
Availability Ratio for Performance of Pipeline Components in Two-Phase Flow
Authors: Harrison R. F. , Dean R. B.
Published: October 2010

A new method is presented which uses the steady flow availability function to analyze the efficiency with which energy can be transmitted in a pipeline. It is suggested that the availability approach can be used to compare the performance of all types of pipeline component such as bends, diffusers, etc., and their effect on the power available at the power turbine.
Calculation of Two-Phase Dispersed Droplet-In-Vapor Flows Including Normal Shock Waves
Authors: Comfort W. J. , Alger T. W. , Giedt W. H. , Crowe C. T.
Published: October 2010

A method for calculating quasi-one-dimensional, steady-state, two-phase dispersed droplet-in-vapor flow has been developed. The technique is applicable to both subsonic and supersonic single component flow in which normal shock waves may occur, and is the basis for a two-dimensional model. The flow is assumed to be inviscid except for droplet drag. Temperature and pressure equilibrium between phases is assumed, although this is not a requirement of the technique. Example calculations of flow in one-dimensional nozzles with and without normal shocks are given and compared with experimentally measured pressure profiles for both low quality and high quality two-phase steam-water flow.
Solutions of Laminar Jet Flow Problems for Non-Newtonian Power-Law Fluids
Authors: Mitwally E. M.
Published: October 2010

Solutions are presented for laminar flow of non-Newtonian power-law fluids. The flow configurations cover the two-dimensional plane and radial free jets, the axisymmetrical (circular) free jet, and the plane and radial wall jets. When the flow behavior index is unity, the present results agree well with those already published for the case of Newtonian fluids.
Laminar Shear Layer Due to a Thin Flat Plate Oscillating With Zero Mean Velocity
Authors: Watkins C. B. , Herron I. H.
Published: October 2010

A numerical solution of the unsteady laminar boundary layer equations is described for the flow due to a semi-infinite plate, sinusoidally oscillating with zero mean velocity. The plate periodically reverses its direction of motion with no net translation. The solution treats the region intermittently occupied by the plate as a thin symmetric wake. A time-centered two-step implicit finite-difference scheme was used with upwind differencing and a variable spatial grid to obtain the numerical results. Results are presented for velocity profiles and surface shear stress as a function of position and time.