bluuebunny/crossref_metadata_2025 huggingface dataset:
An integrative review of nurse‐led community‐based case management effectiveness
Authors: Joo J. Y. , Huber D. L.
Published: November 2013

Background

Accountable, continuous and patient‐centred care in community‐based settings is increasingly needed to reduce fragmented care, especially to reduce patient readmission rates. Case management has been proven effective in reducing healthcare costs and in increasing continuity of care, but its effectiveness in community‐based settings is not clear.

Aim

The aim of this integrative review is to examine the effectiveness of community‐based case management programmes in improving patient outcomes.

Methods

An integrative review of articles from PubMed, CINAHL and PsycInfo databases was undertaken to synthesize and analyse research about community‐based case management and its outcomes. Studies looking for patient outcomes and empirical studies published since 2000 were included. A total 18 articles were retrieved from 2000 to 2013.

Results

Most of the included studies were conducted in the USA, but international studies with quantitative approaches were reviewed (n = 6). The review revealed that community‐based case management significantly reduced hospital access outcomes, especially readmissions and increased cost effectiveness, patient clinical outcomes and patient satisfaction.

Limitations

This study did not isolate studies of patients with diseases or demographic characteristics in common, resulting in large variations in disease and demographic factors.

Conclusion

There is a base of evidence that community‐based case management is effective. Because it provides quality, patient‐centred care, case management should be used for major care coordination.

Implications for Nursing and Health Policy

The benefits of community‐based case management need to be announced to healthcare leaders and policymakers.
Low‐Temperature Sinterable (1−x)Ba3(VO4)2–xLiMg0.9Zn0.1PO4 Microwave Dielectric Ceramics
Authors: Lv Yang , Zuo Ruzhong , Cheng Ying , Zhang Chen
Published: November 2013

The novel low‐temperature sinterable (1 − x)Ba3(VO4)2–xLiMg0.9Zn0.1PO4 microwave dielectric ceramics were prepared by cofiring the mixtures of pure‐phase Ba3(VO4)2 and LiMg0.9Zn0.1PO4. The phase structure and grain morphology of the ceramics were evaluated using X‐ray diffraction, Raman spectra, and scanning electron microscopy. The results indicated that Ba3(VO4)2 and LiMg0.9Zn0.1PO4 phases can well coexist in the sintered body. Nevertheless, a small amount of LiZnPO4 and some vanadate phases with low melting points were observed, which not only can influence the microwave dielectric properties of the ceramic but also can obviously improve the densification behavior at a relatively low sintering temperature. The near‐zero temperature coefficients of the resonant frequency (τf) could be achieved by adjusting the relative content of the two phases owing to their opposite τf values and simultaneously a desirable quality factor Q × f value can be maintained. No chemical reaction between the matrix ceramic phase and Ag took place after sintering at 800°C for 4 h. The ceramics with 45 vol% LiMg0.9Zn0.1PO4 can be well sintered at only 800°C and exhibit excellent microwave dielectric properties of εr ~ 10, Q × f ~ 64 500 GHz, and τf ~ −2.1 ppm/°C, thus showing a great potential as a low‐permittivity low‐temperature cofired microwave dielectric material.
Inhomogeneous Structure and Magnetic Properties of Aurivillius Ceramics Bi4Bin−3Ti3Fen−3O3n+3
Authors: Li Jing‐Bo , Huang Yong‐Ping , Jin Hai‐Bo , Rao Guang‐Hui , Liang Jing‐Kui
Published: November 2013

Structures of Aurivillius ceramics Bi4Bin − 3Ti3Fen − 3O3n+3 with n = 3–9 have been investigated by X‐ray powder diffraction and high‐resolution transmission electron microscopy. The Aurivillius ceramics Bi4Bin−3Ti3Fen−3O3n+3 with n = 3–5 exhibit homogeneous layered structure. However, the ceramic samples with n = 6–9 are composed of mixed Aurivillius phases with different layer numbers, in which the stacking faults of the disordered intergrowth of different n‐layered perovskite blocks and the so‐called “side‐stepping” of the (Bi2O2)2+ layers are generally observed. Magnetic measurements indicate that Fe cations couple antiferromagnetically and the inhomogeneity of composition exists in the samples. The magnetic properties are obviously influenced by the inhomogeneous structure and composition.
Schisandrin B attenuates acetaminophen‐induced hepatic injury through heat‐shock protein 27 and 70 in mice
Authors: Li Libo , Zhang Tiran , Zhou Li , Zhou Li , Xing Guihua , Chen Yuhang , Xin Yabing
Published: November 2013

Background and Aim

Schisandrin B is an active component isolated from Schisandra chinensis (TurcZ.) Baill. that is widely used as an antihepatotoxic agent. Schisandrin B has significant hepatoprotective effect against chemical and immunological liver injury. This study aimed to investigate the effect of Schisandrin B on the expression of 27‐ and 70‐kDa heat‐shock protein (HSP) and its role in protection against acetaminophen‐induced liver injury in mice.

Methods

After the mice were pretreated, Western blot and real‐time quantitative polymerase chain reaction were used to detect the protein and gene expression of HSP27 and HSP70, respectively; the liver tissues were subjected to histological evaluation, and alanine aminotransferase and aspartate aminotransferase activities in the serum were measured.

Results

Oral administration of Schisandrin B increased the expression of HSP27 and HSP70 in a time‐ and dose‐dependent manner. The inducing effect of Schisandrin B on HSP27 and HSP70 was also confirmed by real‐time quantitative polymerase chain reaction. In the acetaminophen‐induced liver injury mouse model, the prior oral administration of Schisandrin B (200 mg/kg) three times in 24 h markedly alleviated liver injury as indicated by the amelioration of histopathological hepatic necrosis and the reduction of alanine aminotransferase and aspartate aminotransferase activities in the serum. However, the earlier actions of Schisandrin B were all suppressed significantly by Quercetin, a known HSP inhibitor.

Conclusion

The hepatic cytoprotective action of Schisandrin B against acetaminophen‐induced liver injury is mediated, at least in part, by the induction of HSP27 and HSP70 in mice.
Prevalence of nonalcoholic fatty liver disease in mainland of China: A meta‐analysis of published studies
Authors: Li ZhanZhan , Xue Jing , Chen Peng , Chen LiZhang , Yan ShiPeng , Liu LiYa
Published: November 2013

Background and Aim

Nonalcoholic fatty liver disease (NAFLD) is becoming an increasingly important health issue. However, there are no data on the change in prevalence of NAFLD within a population over time, especially in the mainland of China. The goal of this study was to estimate the pooled prevalence of NAFLD in the mainland of China.

Methods

Systematic literature searches were conducted in PubMed, Web of Knowledge, Chinese Web of Knowledge, Wangfang, Weipu, and SinoMed databases, as well as relevant articles published from 1997 to 2013, reporting prevalence estimates of NAFLD in the mainland of China. Summary estimates of prevalence were calculated with a random effects model. The effects of research methodology on the prevalence estimates were assessed using a meta‐regression model.

Results

Forty‐eight studies were identified with of a total of 356 367 subjects. The overall pooled prevalence of NAFLD was 20.09% (17.95–22.31%). Subgroup analyses showed the following results: male: 24.81% (21.88–27.87%), female: 13.16% (11.33–15.11%), for 18–30: 9.22% (6.93–11.81%), for 40: 16.77% (13.22–20.66%), for 50: 23.50% (19.57–27.66%), for 60: 26.89% (21.11–33.09%), for urban: 21.83% (18.00–25.92%), for rural: 20.43% (8.01–36.74%); study years in 2000–2006: 18.22% (14.32–22.48%), 20.00% (16.84–23.36%) for 2007–2009, and 18.93% (15.41–22.72%) for 2010–2013.

Conclusions

The prevalence of NAFLD is lower than the estimates from developed countries. But it still reaches the epidemic proportions, and its prevalence is increasing. Meanwhile, a nationwide prevalence investigation should be conducted to confirm the estimates and determine more accurate rates for specific populations.
miR‐224 promotion of cell migration and invasion by targeting Homeobox D 10 gene in human hepatocellular carcinoma
Authors: Li Qiong , Ding Chenchen , Chen Chuan , Zhang Zhimin , Xiao He , Xie Fei , Lei Lin , Chen Yuanyuan , Mao Bijing , Jiang Mei , Li Jian , Wang Dong , Wang Ge
Published: November 2013

Background and Aim

MicroRNAs (miRNAs) are small noncoding RNA molecules that control target gene expression and are implicated in the regulation of diverse cellular pathways. In our previous research, we have demonstrated that miR‐224 was overexpressed in liver cancer cells and tissues, which was an important factor in the regulation of cell migration and invasion. This study aimed to further explore the regulatory mechanism of miR‐224 in the migration and invasion in liver cancer cells.

Methods

A luciferase reporter assay was used to confirm that the HOXD10 gene was a direct target of miR‐224. Quantitative reverse transcriptase‐polymerase chain reaction, Western blotting, Transwell migration, and Matrigel invasion assays were performed to clarify the molecular mechanism of miR‐224 in the regulation of cell migration and invasion in human hepatocellular carcinoma (HCC).

Results

 (i) The expression of miR‐224 was strongly upregulated in MHHC97H and MHCC97L cells, and its expression level was significantly associated with cell invasive potential. (ii) The HOXD10 gene was confirmed to be a direct target of miR‐224. Compared with normal liver tissues and cells, HOXD10 had lower expression in HCC tissues and cells and inversely regulated HCC cell invasion. (iii) miR‐224 promoted expression of the tumor invasion‐associated proteins p‐PAK4 and MMP‐9 by directly targeting HOXD10.

Conclusion

Our findings suggest a previously undescribed regulatory pathway in which the miR‐224/HOXD10/p‐PAK4/MMP‐9 signaling pathway contributes to the regulation of cell migration and invasion and provides a new biotarget for HCC treatment.
Immunohistochemical localization of connective tissue growth factor, transforming growth factor‐beta1 and phosphorylated‐smad2/3 in the developing periodontium of rats
Authors: Li S. , Ge S. , Yang P.
Published: November 2013

Background and Objective

Connective tissue growth factor (CTGF) is a downstream mediator of transforming growth factor‐beta1 (TGF‐β1), and TGF‐β1‐induced CTGF expression is regulated through the SMAD pathway. CTGF is implicated in the development of cartilage, bone and tooth. However, its expression in the developing periodontium is unclear. Therefore, we aimed to investigate the immunolocalization of CTGF, TGF‐β1 and phosphorylated SMAD2/3 (pSMAD2/3) in the developing periodontium of rats.

Material and Methods

The maxillaries of Wistar rats, 2, 3, 7 and 12 wk of age, were used and the localization of CTGF, TGF‐β1 and pSMAD2/3 was detected using immunoperoxidase techniques.

Results

Hertwig' s epithelial root sheath (HERS) cells were strongly positive for CTGF and TGF‐β1, but not for pSMAD2/3. Positive staining for CTGF, TGF‐β1 and pSMAD2/3 was found in bone and periodontal ligament. In cementum, most cementoblasts associated with cellular cementum and some cementocytes stained strongly for CTGF, whereas cementoblasts associated with acellular cementum did not express CTGF. No signal for TGF‐β1 was observed in cellular and acellular cementum. In addition, most cementocytes were strongly positive for pSMAD2/3.

Conclusion

CTGF, TGF‐β1 and pSMAD2/3 are localized in bone and periodontal ligament, but are differentially expressed in HERS and cementum. The results of our study indicate that the regulation of CTGF expression by TGF‐β1 might be cell‐type specific in periodontium.
Functional and evolutionary analyses of Primulina heterotrichaCYC1C gene in tobacco and Arabidopsis transformation systems
Authors: LIU Bo‐Ling , PANG Hong‐Bo , YANG Xia , WANG Yin‐Zheng
Published: November 2013

In Asterids, specific expression of CYC‐like genes in the corresponding regions promotes or reduces dorsal petal growth and aborts stamen development. In Rosids, however, the reduced or enlarged dorsal petals are not accompanied by the abortion of stamens, which implies that the function of CYC‐like genes in regulating petal growth and stamen development might be independently recruited. To address this, we investigated the function of the PhCYC1C gene in Primulina heterotricha Y. Dong & Y. Z. Wang on petal growth and stamen development by overexpressing it in two different transformation systems, that is, Arabidopsis belonging to Rosids and tobacco located in Asterids. The results showed that overexpression of PhCYC1C reduced petal sizes in both tobacco and Arabidopsis transgenic plants mainly by repressing cell expansion, indicating its conserved function in determining petal growth between Asterids and Rosids. However, the fertility of both tobacco and Arabidopsis stamens was not affected at all. Given that strong expression signals of PhCYC1C are detected in both tobacco and Arabidopsis stamens and CYC‐like genes actually function to repress stamen development in Lamiales, we suggest that the CYC‐like gene‐associated regulatory network for controlling stamen development might have not established in Rosids as well as in early evolution of Asterids, but evolved as Asterids proceeded further. Our results provide valuable information on the conservation of CYC‐like genes' function in controlling corolla asymmetry and the divergence of their function in determining stamen abortion in angiosperms.
Effect of antimicrobial agents incorporated into resilient denture relines on the Candida albicans biofilm
Authors: Bueno MG , Urban VM , Barbério GS , da Silva WJ , Porto VC , Pinto LdeR , Neppelenbroek KH
Published: November 2013

Objective

The antimicrobial action of five drugs incorporated in temporary denture relines on the fungal biofilm was evaluated.

Materials and Methods

A Candida albicans biofilm (SC5314) was formed on specimens (10 × 1 mm) of materials (Trusoft and Softone) modified or not (control) by the drugs (nystatin, miconazole, ketoconazole, itraconazole, and chlorhexidine diacetate). Cell viability was determined spectrophotometrically by the tetrazolium salt reduction assay (XTT) after 24 h, 48 h, and 7 and 14 days of incubation. The minimum inhibitory concentrations (MICs) were those which inhibited 90% or more of fungal growth. Fungal susceptibility was confirmed by confocal laser scanning microscopy analysis.

Results

The MICs of drugs incorporated in the materials were 0.032, 0.256, 0.128, 0.256, and 0.064 g ml−1 for nystatin, miconazole, ketoconazole, itraconazole, and chlorhexidine, respectively. Images from nystatin, chlorhexidine, and ketoconazole demonstrated no viable cells.

Conclusions

The antimicrobials incorporated in the resilient materials inhibited fungal growth during 14 days, with lower MICs for nystatin and chlorhexidine.
Model Selection for Estimating Treatment Effects
Authors: Rolling Craig A. , Yang Yuhong
Published: November 2013

Researchers often believe that a treatment's effect on a response may be heterogeneous with respect to certain baseline covariates. This is an important premise of personalized medicine. Several methods for estimating heterogeneous treatment effects have been proposed. However, little attention has been given to the problem of choosing between estimators of treatment effects. Models that best estimate the regression function may not be best for estimating the effect of a treatment; therefore, there is a need for model selection methods that are targeted to treatment effect estimation. We demonstrate an application of the focused information criterion in this setting and develop a treatment effect cross-validation aimed at minimizing treatment effect estimation errors. Theoretically, treatment effect cross-validation has a model selection consistency property when the data splitting ratio is properly chosen. Practically, treatment effect cross-validation has the flexibility to compare different types of models. We illustrate the methods by using simulation studies and data from a clinical trial comparing treatments of patients with human immunodeficiency virus.
An Extended Study of Seroprevalence of Anti‐Anisakis simplex IgE Antibodies in Norwegian Blood Donors
Authors: Lin A. H. , Nepstad I. , Florvaag E. , Egaas E. , Van Do T.
Published: November 2013

During the last decade, cases of the fish parasite Anisakis simplex infection and allergy in human have increased in countries with high fish consumption. Our aim was to perform an extended seroprevalence study of anti‐IgE antibodies against this parasite in Norway, one of the high fish‐consuming countries. At the Department of Immunology and Transfusion Medicine and the Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway, two main groups of anonymized serum samples were collected; the first (n = 993) from recently recruited blood donors (designated ‘BDO’) and the second (n = 414) from patient with total IgE levels ≥1000 kU/l (designated ‘IGE+’). The sera were analysed by the ImmunoCAP® method for total IgE and IgE antibodies against A. simplex, house dust mite (HDM), shrimp, cod, crab, brine shrimp and shrimp tropomyosin. The A. simplex positive sera were further tested by an enzyme‐linked immunosorbent assay (ELISA) method, which uses 2 recombinant (r) major allergens, rAni s 1 and rAni s 7 as target antigens. SDS‐PAGE and Western immunoblotting analyses were also performed. Whereas the prevalences by ImmunoCAP® were 0.4% and 16.2% in the BDO and IGE+ groups, respectively, analyses with recombinant allergens showed only 0.0% and 0.2%. Cross‐reactivity and immunoblotting analyses suggested that most of the ImmunoCAP® positive sera were probably false‐positive due to cross‐sensitization to shrimp and HDM. However, positivity due to other A. simplex antigens should also be considered. Compared with other high fish‐consuming countries, we observed a very low seroprevalence of anti‐Anisakis IgE antibodies in a Norwegian population.
National health insurance scheme enrolment and antenatal care among women in Ghana: is there any relationship?
Authors: Dixon Jenna , Tenkorang Eric Y. , Luginaah Isaac N. , Kuuire Vincent Z. , Boateng Godfred O.
Published: November 2013

Objectives

The objective of this study was to examine whether enrolment in the National Health Insurance Scheme (NHIS) affects the likelihood and timing of utilising antenatal care among women in Ghana.

Methods

Data were drawn from the Ghana Demographic and Health Survey, a nationally representative survey collected in 2008. The study used a cross‐sectional design to examine the independent effects of NHIS enrolment on two dependent variables (frequency and timing of antenatal visits) among 1610 Ghanaian women. Negative binomial and logit models were fitted given that count and categorical variables were employed as outcome measures, respectively.

Results

Regardless of socio‐economic and demographic factors, women enrolled in the NHIS make more antenatal visits compared with those not enrolled; however, there was no statistical association with the timing of the crucial first visit. Women who are educated, living in urban areas and are wealthy were more likely to attend antenatal care than those living in rural areas, uneducated and from poorer households.

Conclusion

The NHIS should be strengthened and resourced as it may act as an important tool for increasing antenatal care attendance among women in Ghana.
Local photodynamic therapy delays recurrence of equine periocular squamous cell carcinoma compared to cryotherapy
Authors: Giuliano Elizabeth A. , Johnson Philip J. , Delgado Cherlene , Pearce Jacqueline W. , Moore Cecil P.
Published: November 2013

Objective

(i) To report the successful treatment of 10 cases of equine periocular squamous cell carcinoma (PSCC) with surgical excision and photodynamic therapy (PDT) using verteporfin. (ii) To evaluate time to first tumor recurrence betweenPDT‐treated horses and horses treated with surgical excision and cryotherapy.

Methods

A total of 24 equinePSCCcases were included: group 1 (n = 14) had excision and cryotherapy (1993–2003), group 2 (n = 10), excision and localPDT(2006–2010). Evaluated data: signalment, treatment method, tumor location, size, and time to first recurrence. Groups were compared via chi‐square test for categorical variables andWilcoxon rank‐sum test for numeric variables. Time to tumor recurrence was examined usingKaplan–Meier product‐limit survival analysis.

Results

Of 24 cases, nine breeds were affected. Mean age at treatment in years: 14 (range 5–24) in group 1; 11 (range 8–18) in group 2. Median tumor size: 163 mm2(range 20–625 mm2) in group 1; 195 mm2(range 45–775 mm2) in group 2. Signalment, tumor laterality, and size were not significantly different between groups. Time to recurrence was significantly different between groups (Logrank test,P = 0.0006). In group 1, 11/14 horses had tumor regrowth with median time to recurrence in months: 10 (range 1–44). In group 2 (minimum follow‐up of 25 months; range 25–50), no horse demonstrated tumor recurrence after one treatment with excision andPDT.

Conclusions

This represents the first report of localPDTusing verteporfin for treatment of equinePSCC. Following surgery, the likelihood of tumor recurrence was significantly reduced with localPDTcompared with cryotherapy.
An Integrated Product Team Approach to the Development of a Complex Rotor System
Authors: Rollon Ryan , Gualtieri Guy , Garcia Manny , Dowd Adam , Johnson P. Dean , Finnegan John , Kobelak Mike , Anthony Rich , Clark John
Published: November 2013

This paper details development efforts for the Turbine Research Facility (TRF) rotor system at the U. S. Air Force Research Laboratory (AFRL). In some previous test programs, the prior TRF rotor drive system was known to experience instances of excessive vibration during spin-up, limiting the robustness of the facility to execute its primary mission of developing advanced turbine aerothermal technologies; this paper will cover redesign and validation of the TRF rotor system to allow that mission to resume safely. First, a brief summary of the root cause investigation of historical rotordynamic issues at the facility is given; this pointed the way for the primary redesign path. Next, rotor system redesign elements will be covered and these are interspersed with design, manufacturing and assembly considerations for rotordynamics trades. This is followed by a discussion of rotordynamics analysis methodologies including the coupling of a one-dimensional beam element code with three-dimensional finite element analyses and laboratory component data to produce high fidelity rotordynamics predictions. In conclusion, test validation specifically concentrating on proximity probe and accelerometer data is presented along with a comparison to design intent. The purpose of this paper is to present an integrated product team (IPT) approach to the development of a complex rotor system solution.
A New Inlet Distortion and Pressure Loss Based Design of an Intake System for Stationary Gas Turbines
Authors: Rodriguez Jose , Klumpp Stephan , Biesinger Thomas , O’Brien James , Danninger Tobias
Published: November 2013

This paper presents a new design for a Compressor Inlet Manifold (CIM) for a land-based power generation Gas Turbine (turbine). The CIM is the component of the Inlet System (IS) that is directly connected to the turbine via the Compressor Inlet Case (CIC). The design philosophy is to use low fidelity but fast and automated CFD (Computational Fluid Dynamics) for design iterations and then confirm the design with detailed higher accuracy CFD before proceeding to engine tests. New design features include contouring the wall to minimize areas of flow separation and associated unsteadiness and losses, and improvement of the flow quality into the compressor.

The CIM in a land-based turbine acts as a nozzle whereas the inlet of an aircraft acts as a diffuser. The flow also enters the CIM at 90 deg to the engine axis. This leads to a pair of counter rotating vortices at the compressor inlet. Three main sources of flow distortions at the face of the compressor are identified: flow separations at outer walls of the IS and CIM struts and the counter rotating vortices. The higher accuracy CFD analysis including the complete IS, CIM and the first compressor stage, simulates the effect of these distortions on the compressor front stage at design conditions. A range of inlet distortion parameters are used to evaluate the inlet design. The well known DC60 based criterion derived from aircraft engines and other less known but published parameters are able to give an indication of how the compressor surge margin of stationary gas turbines is affected.
Experiments With Scaled Foil Bearings in a Test Compressor Rotor
Authors: De Santiago Oscar , Solórzano Víctor
Published: November 2013

Gas bearings are a promising technology for rotor support due to their inherent ability to work with process fluids in gas compression turbomachines. This feature has potential for eliminating oil systems, providing a clean operation and substantially reducing operating costs. This paper presents initial experiments of a 59 kg (130 lb) test compressor rotor supported on a pair of 90.20 mm (3.551 in) diameter metal-mesh foil bearings lubricated with ambient air in a rotordynamic test rig running at 9,000 rpm without gas compression. The configuration includes relocation of the bearing supports inboard of the gas seals to reduce bearing span, favoring a more stable configuration of the rotor-bearing system. Test foil bearings are designed to support static loads due to rotor weight and remnant imbalance levels. Test results show that the bearings are capable of supporting design loads and running at moderate vibration levels. A slow-growing subsynchronous vibration appears after a stable period at full speed as a result of top foil damage in the free end bearing during the run-up. This damage is due to lack of axial rotor constraints. The results of the experiments indicate that metal mesh foil bearings are a promising technology towards oil-free supported turbomachinery at larger scales than previously utilized.
A Novel Combination of Adaptive Tools for Turbomachinery Airfoil Shape Optimization Using a Real-Coded Genetic Algorithm
Authors: Safari A. , Lemu H. G. , Assadi M.
Published: November 2013

An automated shape optimization methodology for a typical heavy-duty gas turbine (GT) compressor rotor blade section is presented in this paper. The approach combines a Non-Uniform Rational B-Spline (NURBS) driven parametric geometry description, a two-dimensional flow analysis, and a Genetic Algorithm (GA)-based optimization route. The objective is minimizing the total pressure losses for design condition as well as maximizing the airfoils operating range which is an assessment of the off-design behavior. To achieve the goal, design optimization process is carried out by coupling an established MATLAB code for the Differential Evolution (DE)-based optimum parameterized curve fitting of the measured point cloud of the airfoils’ shape, a blade-to-blade flow analysis in COMSOL Multiphysics, and a developed real-coded GA in MATLAB script. Using the combination of these adaptive tools and methods, the first results are considerably promising in terms of computation time, ability to extend the methodology for three-dimensional and multidisciplinary approach, and last but not least airfoil shape performance enhancement from efficiency and pressure rise point of view.
From Rotating Stall to Surge: A Shock Tube Mechanism
Authors: Huang Paul Xiubao , Yin JianAn
Published: November 2013

Compressor surge is a complete breakdown in compression resulting in an abrupt momentary reversal of gas flow and the violent pressure fluctuation with relatively low frequency and high amplitude. It commonly exists in dynamic type turbo compressors, particularly axial compressor and jet engine, or turbo charger for reciprocating engines. It is generally accepted that surge is preceded by a rotating stall, a situation of a few stalled blades rotating around compressor annulus (cascade) with much higher frequency. In jet engine, violent surge event typically produces a frightening loud bang, lots of vibrations and could cause catastrophic structural failures if not timely managed.

Naturally, as important matters as rotating stall and surge, there have been tremendous R/D efforts from academia, government and industry devoted to this area, especially since jet engines became the prime powerhouses for modern airplanes. Despite of all the efforts, there still seems to be a more urgent need to understand the physical characteristics of the transition from a rotating stall to surge that has mystified researchers due to its transient nature. Fundamental questions remain unanswered even today, such as: What exactly triggers the surge to take place from a rotating stall? What is the physical nature of a compressor system or a local incipient surge: is it a movement of wave or fluid particles or both? How to estimate the quantitative destructive forces of a severe surge, that is, the maximum possible surge strength?

This paper attempts to answer these questions by applying the classical Shock Tube Theory to the transient process from rotating stall to surge. The Shock Tube analogy is established with the hypothesis (implied from experimental observations) that an instant zero through flow condition exists inside a stalled cascade cell or dynamic compressor that triggers surge. It is revealed that surge event consists of a pair of non-linear compression and expansion waves (CW & EW) that instantly reverse gas flow (IRFF) by the pushing force of upstream propagating CW and the pulling force from downstream travelling EW. The surge strength is shown to be proportional to the square root of the pressure ratio of the involved cascade or compressor. Surge Rules are deduced to predict the location of surge initiation, the minimum and maximum surge strengths, travelling directions and speed. Moreover, a pro-active control strategy called SEWI (Surge Early Warning Initiative) is proposed using the unique characteristics of CW-IRFF-EW formation of a cascade cell induced surge as precursors for subsequent warning and controls before the destructive compressor surge takes place.
Forced Response Analysis of a Mistuned Compressor Blisk
Authors: Beirow Bernd , Kühhorn Arnold , Giersch Thomas , Nipkau Jens
Published: November 2013

The forced response of an E3E-type HPC-blisk front rotor is analyzed with regard to varying mistuning and the consideration of the fluid-structure interaction (FSI). For that purpose, a reduced order model is used in which the disk remains unchanged and mechanical properties of the blades namely stiffness and damping are adjusted to measured as well as intentional blade frequency mistuning distributions. The aerodynamic influence coefficient technique is employed to model the aeroelastics. Depending on the blade mode, the exciting engine order and aerodynamic influences it is sought for the worst mistuning distributions with respect to the maximum blade displacement based on optimization analyses. Genetic algorithms using blade alone frequencies as design variables are applied. The validity of the Whitehead-limit is assessed in this context. In particular, the question is addressed if and how far aeroelastic effects, mainly caused by aerodynamic damping, combined with mistuning can even cause a reduction of the forced response compared to the ideally tuned blisk. It is shown that the strong dependence of the aerodynamic damping on the inter-blade phase angle is the main driver for a possible response attenuation considering the fundamental as well as a higher blade mode. Furthermore, the differences to the blisk vibration response without a consideration of the flow and an increase of the disk’s stiffness are discussed. Closing, the influence of pure damping mistuning is analyzed again using optimization.
Exact Solution of Radial Displacement and Stress of Rotating Elastic Interference Fits
Authors: Feng Sheng , Geng Haipeng , Yang Baisong , Yu Lie , Yang Lihua , Zhou Jian , Zhao Shiquan
Published: November 2013

Interference fits, which are widely used in flexible couplings, can transfer large torques while avoiding unbalance. Using the classic elastic plane stress theory, the equations of the rotating interference fits taking into account of the temperature changes are derived, and the exact solution of radial displacement and radial stress, hoop stress and tangential stress of the rotating interference fits are obtained, then taking the interference fits of the coupling for a high speed microturbomachinery as an example, the above solutions are plotted using the numerical method, and also Von Mises equivalent stress is calculated. It is found that there are significantly different for the radial displacements between the two cases of with/without taking into account the change of temperature under two kinds of parameters, one is rotating speed chosen as a parameter and other parameters keeps constant, the other is the inner radius of the shaft and rotating speed chosen as parameters.
CFD Investigation on the Rotordynamic Characteristics of Shroud Leakage Flow in High Pressure Steam Turbine
Authors: Nishijima Noriyo , Endo Akira , Yamaguchi Kazuyuki
Published: November 2013

We conducted a computational fluid dynamics (CFD) study to investigate the rotordynamic characteristics of the shroud labyrinth seal of a high-pressure steam turbine.

Four different CFD models were constructed to investigate the appropriate modeling approach for evaluating the seal force of an actual steam turbine because shroud seals are generally short with fewer fins and the effect of surrounding flow field is thought to be large. The four models are a full model consisting of a 1-stage stator/rotor cascade and a labyrinth seal over the rotor shroud, a guide-vane model to simulate the condition similar to seal element experiments, and two other simplified models. The calculated stiffness coefficients of the four models did not agree and fell into two groups. Through careful investigations of flow fields, it was found that the difference could be explained by the circumferential mass flow distribution at the seal inlet and the mass flow bias rate is an important factor in evaluating the seal force of a turbine shroud. The results also indicate that the rotordynamic characteristics obtained from seal element experiments may differ from those of actual turbines, especially in short seals.
Geometric Mistuning Reduced Order Models for Integrally Bladed Rotors With Mistuned Disk-Blade Boundaries
Authors: Beck Joseph A. , Brown Jeffrey M. , Cross Charles J. , Slater Joseph C.
Published: November 2013

New geometric mistuning approaches for integrally bladed rotors (IBRs) are developed for incorporating geometric perturbations to a fundamental disk-blade sector, particularly the disk-blade boundary, or connection. The developed Reduced Oder Models (ROMs) are formulated from a Craig-Bampton component mode synthesis (C-B CMS) framework that is further reduced by a truncated set of interface modes that are obtained from an eigen-analysis of the C-B CMS constraint degrees of freedom (DOFs). An investigation into using a set of tuned interface modes and tuned constraint modes for model reduction is then performed. A tuned mode approximation has the added benefit of being only calculated once which offers significant computational savings for subsequent analyses. Two configurations of disk-blade connection mistuning are investigated: as-measured principal component deviations and random perturbations to the inter-blade spacing. Furthermore, the perturbation sizes are amplified to investigate the significance of incorporating mistuned disk-blade connection. Free and forced response results are obtained for each ROM and each disk-blade connection type and compared to full finite element model (FEM) solutions. It is shown that the developed methods provide highly accurate results with a significant reduction in solution time compared to the full FEM. In addition, results indicate that the inclusion of a mistuned disk-blade connection becomes significant as the size of the geometric deviations at the connection become large.
Transitional Effects of Active Micro-Tabs for Wind Turbine Load Control
Authors: Bach A. B. , Holst D. , Nayeri C. N. , Paschereit C. O.
Published: November 2013

Wind turbines generally suffer from unsteady inflow caused by yaw misalignment, gusts, and turbulence which induce fatigue loads. Spanwise distributed active micro-tabs at the mid and outer blade regions are able to countervail these unsteady loads. However, during the actuation process of these devices, transient effects play an important role. This work aims to give a deeper insight in the process of the tab deployment and retraction to evaluate the effectiveness of active micro-tabs for load control on wind turbines. Wind tunnel experiments on a two-dimensional NACA 0018 airfoil with an active micro-tab were conducted. The tab deployment- and retraction time was varied for an application on the suction or the pressure side of the airfoil. Time resolved surface pressure measurements were performed at Reynolds numbers of Re = 7 · 105 and 1 · 106. Transient responses showed a significant delay and post deployment behavior of the lift which strongly depend on the actuation time.
Investigation of Compressor Tip Clearance Flow Based on the Discontinuous Galerkin Methods
Authors: Ren Xiaodong , Gu Chunwei
Published: November 2013

The tip clearance flow has a significant influence on the compressor performance and stability. CFD, which is a current tool, has been widely used to investigate the flow by many researchers. In this paper, an unstructured-grid code based on a RKDG method was developed with an improved vertex-based slope limiter to ensure the nonlinear stability. The limiter tests show that the improved limiter has less numerical dissipation and it can keep the high-order accuracy.

The performance for NASA Rotor 37 was simulated to validate the RKDG code. The results are compared with the experimental data and the ones computed by NUMECA FINE™/Turbo. It is shown that the results computed by the RKDG code are in better agreement with the experimental data, which implies that the high-order accuracy method is very important for improving the CFD reliability.

Finally, the tip clearance flow of the compressor was investigated using the RKDG code. It is found that the tip leakage jet flow could be separated into two parts and they go downstream separately without mixing.
Eliminating Carcinogens in Compressor Coatings
Authors: Klotz Kevin , Klotz Brian , McMordie Bruce
Published: November 2013

Introduced almost fifty years ago on steel compressor cases in J-79 engines, aluminum-ceramic coatings have come to play an essential role in protecting steel components in turbines and turbomachinery. The water-based “spray and bake” inorganic phosphate-base coatings are uniquely resistant to salt corrosion and heat, but pressure is growing to find an alternative to these materials. The slurries contain hexavalent chromium (Cr(VI)), a known carcinogen. In Europe, REACH initiatives restrict import and use of solutions containing hexavalent chromium. In the US, workplace exposure to Cr(VI) is limited to a mere 0.005 mg/m3 (5 micrograms) of Cr(VI) per person per 8 hour day and employers must monitor the health of those exposed even to such low levels. Aluminum-phosphate slurries clean up with water, but all effluent liquid must be captured and treated to remove Cr(VI). Solid waste that comes in contact with the slurry or rinse water must be segregated for proper disposal. Efforts to develop a safe, aluminum-phosphate coating without hexavalent chromium began in the early 1990s, but have met with limited success. Recently, a sacrificial, heat resistant aluminum-ceramic has been developed that contains no hazardous materials. This paper will review efforts to develop Cr-free Al-ceramic coatings and explain the promise of a new product that uses a different chemistry to produce an aluminum-ceramic coating that is protective, yet inherently non-hazardous.
A Parametric Study of an Exhaust Recovery Turbogenerator on a Diesel-Electric Hybrid Bus
Authors: Briggs Ian , McCullough Geoffrey , Spence Stephen , Douglas Roy , O’Shaughnessy Richard , Hanna Alister , Rouaud Cedric , Seaman Rachel
Published: November 2013

The fuel consumption of automotive vehicles has become a prime consideration to manufacturers and operators as fuel prices continue to rise steadily, and legislation governing toxic emissions becomes ever more strict. This is particularly true for bus operators as government fuel subsidies are cut or removed.

In an effort to reduce the fuel consumption of a diesel-electric hybrid bus, an exhaust recovery turbogenerator has been selected from a wide ranging literature review as the most appropriate method of recovering some of the wasted heat in the exhaust line. This paper examines the effect on fuel consumption of a turbogenerator applied to a 2.4-litre diesel engine.

A validated one-dimensional engine model created using Ricardo WAVE was used as a baseline, and was modified in subsequent models to include a turbogenerator downstream, and in series with, the turbocharger turbine. A fuel consumption map of the modified engine was produced, and an in-house simulation tool was then used to examine the fuel economy benefit delivered by the turbogenerator on a bus operating on various drive-cycles.

A parametric study is presented which examined the performance of turbogenerators of various size and power output. The operating strategy of the turbogenerator was also discussed with a view to maximising turbine efficiency at each operating point.

The performance of the existing turbocharger on the hybrid bus was also investigated; both the compressor and turbine were optimised and the subsequent benefits to the fuel consumption of the vehicle were shown.

The final configuration is then presented and the overall improvement in fuel economy of the hybrid bus was determined over various drive-cycles.
Sensitivity Assessment of Wound Rotor Induction Generator Bearing Fault Detection Using Machine Electrical Quantities
Authors: Vilchis-Rodriguez Damian S. , Djurović Sinisa , Smith Alexander C.
Published: November 2013

This paper investigates the sensitivity of machine electrical quantities when employed as a means of bearing fault detection in wound rotor induction generators. Bearing failure is the most common failure mode in rotating AC machinery. With the widespread use of wound rotor induction machines in modern wind power generation, achieving effective detection of bearing faults in these machines is becoming increasingly important in order to minimize wind turbine maintenance related downtime. Current signature analysis has been demonstrated to be an effective technique for achieving detection of different fault types in ac machines. However, this technique lacks sensitivity when used for detection of bearing failures and therefore sophisticated post processing techniques have recently been suggested to improve its performance. As an alternative, this paper investigates the sensitivity of a range of machine electrical quantities to bearing faults, with the aim of examining the possibility of achieving improved bearing fault detection based on identifying a clear fault spectral signature. The reported signatures can be subjected potentially to refined processing techniques to further improve fault detection.
Effect of Turbulent Intensity and Axial Gap on Turbine Heat Transfer Using Steady and Harmonic Models
Authors: Murari Sridhar , Sathish Sunnam , Bommisetty Ramakumar , Liu Jong S.
Published: November 2013

The knowledge of heat loads on the turbine is of great interest to turbine designers. Turbulence intensity and stator-rotor axial gap plays a key role in affecting the heat loads. Flow field and associated heat transfer characteristics in turbines are complex and unsteady. Computational fluid dynamics (CFD) has emerged as a powerful tool for analyzing these complex flow systems. Honeywell has been exploring the use of CFD tools for analysis of flow and heat transfer characteristics of various gas turbine components. The current study has two objectives. The first objective aims at development of CFD methodology by validation. The commercially available CFD code Fine/Turbo is used to validate the predicted results against the benchmark experimental data. Predicted results of pressure coefficient and Stanton number distributions are compared with available experimental data of Dring et al. [1]. The second objective is to investigate the influence of turbulence (0.5% and 10% Tu) and axial gaps (15% and 65% of axial chord) on flow and heat transfer characteristics. Simulations are carried out using both steady state and harmonic models. Turbulence intensity has shown a strong influence on turbine blade heat transfer near the stagnation region, transition and when the turbulent boundary layer is presented. Results show that a mixing plane is not able to capture the flow unsteady features for a small axial gap. Relatively close agreement is obtained with the harmonic model in these situations. Contours of pressure and temperature on the blade surface are presented to understand the behavior of the flow field across the interface.
Influence of Oxide Particle Size on the Erosion of the Control Stage Nozzle in a Supercritical Steam Turbine
Authors: Cai Liu-xi , Wang Shun-sen , Zhang Lei , Mao Jing-ru , Feng Zhen-ping , Zhang Jun-jie , Xu Ya-tao
Published: November 2013

Reducing the solid particle erosion (SPE) of blades is one of the most important problems for high-parameter steam turbine. Based on the erosion rate models and the particle rebound models of blade materials obtained through the accelerated erosion test under high temperature, a lot of three dimension numerical simulations were conducted in this paper. The influence of particle size on the impingement point distribution on the nozzle surface and the erosion characteristics of control stage nozzle in a supercritical steam turbine were analyzed quantitatively. The size range of the oxide scale particles participating in the erosion damage were extended to 500μm, and some special anti-erosion measures corresponding to different size particles were proposed to reduce the erosion of nozzle. Results show that the erosion of pressure surface in the trailing edge of nozzle is mainly from the high-intensity impingement of particles smaller than 160μm, especially those with the size range from 20μm to 60μm. For the impingement of these small particles, optimizing the profile and cascade structure as well as coating the hard coating on the surface of nozzle can improve the erosion resistance of nozzle. However, these small particles do not impinge the nozzle trailing edge suction surface. The severe erosion damage of suction surface of nozzle was from the impingement again of the particles with the size range from 200μm to 500μm after rebounding from nozzle pressure surface. It is very difficult to resist the erosion damage of these large particles for the hard coating, and separating large particles from main steam before entering the nozzle chamber should be a good choice for improving the erosion resistance of turbine. These studies will provide a technical basis for selecting anti-erosion measures of control stage nozzle.