bluuebunny/crossref_metadata_2025 huggingface dataset:
Health‐related quality of life in preschool children with Type 1 diabetes
Authors: Sundberg F. , Sand P. , Forsander G.
Published: August 2014

Aims

To describe health‐related quality of life in children aged < 7 years with Type 1 diabetes mellitus compared with healthy children of the same age, and to investigate how health‐related quality of life was correlated with aspects of insulin treatment and glycaemic control.

Methods

The participants in this study were 24 children with diabetes (12 girls, mean age 4.5 years) and 27 healthy children (14 girls, mean age 4.6 years). All participants completed the Pediatric Quality of Life Inventory 4.0 Generic Core Scales and the participants with diabetes also completed the Pediatric Quality of Life Inventory 3.0 Type 1 Diabetes Module Scales. HbA1c levels were measured in children with diabetes and the plasma glucose meter memories were uploaded.

Results

Children aged <7 years with diabetes had lower parent‐rated generic health‐related quality of life compared with healthy children (score: 80 vs 91; P = 0.003). The difference was largest in children aged < 5 years (score: 79 vs 93; P = 0.004). Among the parents of children with Type 1 diabetes, 22% rated their child's generic health‐related quality of life to be at a level of concern (– 1 sd of a general population). Of the children with Type 1 diabetes aged between 5 and 7 years, 40% rated their own generic health‐related quality of life at the same level of concern.

Conclusion

This study shows a significantly lower level of generic health‐related quality of life in very young children with diabetes in comparison with healthy children. We suggest screening for health‐related quality of life in children of all ages with Type 1 diabetes mellitus.
Determination of deferasirox plasma concentrations: do gender, physical and genetic differences affect chelation efficacy?
Authors: Mattioli Francesca , Puntoni Matteo , Marini Valeria , Fucile Carmen , Milano Giulia , Robbiano Luigi , Perrotta Silverio , Pinto Valeria , Martelli Antonietta , Forni Gian Luca
Published: August 2014

Objectives

Bioavailability of deferasirox (DFX) is significantly affected by the timing of administration relative to times and to composition of meals. Its elimination half‐life is also highly variable – in some patients as a result of gene polymorphisms. Understanding whether deferasirox plasma levels are related to specific characteristics of patients could help physicians to devise a drug regimen tailored the individual patient.

Methods

We analyzed deferasirox plasma concentrations (CDFX) in 80 patients with transfusion‐dependent anemias, such as thalassemia, by a high performance liquid chromatography (HPLC) assay. We used a multivariate linear regression model to find significant associations between CDFX and clinical/demographical characteristics of patients. All patients were genotyped for UGT1A1.

Results

Fifty‐six patients were female, 24 were male, the great majority (88%) affected by β‐thalassemia, and 15 were children and adolescents. No statistical correlation was detectable between CDFX and DFX dose (P = 0.6). Age, time from last drug intake to blood sampling, and ferritin levels in the 6 months before study initiation were significantly and inversely associated with CDFX in univariate analysis. In the multivariate analysis, the only two factors independently and inversely associated with CDFX levels were time from last drug intake to blood sampling and ferritin levels (P = 0.006). A significant inverse correlation (P = 0.03) was observed between CDFX and UGT1A1*28 gene polymorphism, but only in patients with levels of lean body mass (LBM) below the median (P for interaction = 0.05).

Conclusions

The results could indicate that a higher plasma DFX concentration could be associated with greater chelation efficacy. As a correlation between dose and CDFX was not demonstrated, it seems useful to monitor the concentrations to optimize and determine the most appropriate dose for each patient. Interesting results emerged from the analysis of genetic and physical characteristics of patients: LBM was a borderline significant effect modifier of the relationship between UGT1A1 polymorphisms and CDFX. Individual patient‐tailored dosing of DFX should help to improve iron chelation efficacy and to reduce dose‐dependent drug toxicity.
Primary antifungal prophylaxis with micafungin in patients with haematological malignancies: real‐life data from a retrospective single‐centre observational study
Authors: Nachbaur David , Angelova Olga , Orth‐Höller Dorothea , Ditlbacher Adelheid , Lackner Michaela , Auberger Jutta , Lass‐Flörl Cornelia
Published: August 2014

Mould‐active antifungal prophylaxis is increasingly used in patients at risk for invasive fungal disease. Between June 2011 and June 2012, one hundred patients with various haematological malignancies at risk for invasive fungal disease received primary antifungal prophylaxis with intravenous micafungin at a daily dosage of 50 mg during neutropenia. The median number of days on micafungin prophylaxis was 14 (range, 6–48 d). The incidence of proven and probable breakthrough invasive fungal diseases (bIFDs) was 6% and 3%, respectively. There were two bloodstream infections caused by yeasts or yeast‐like fungi (Candida krusei, Trichosporon asahii) in two patients during the neutropenic phase after allogeneic haematopoietic stem cell transplantation. Four proven bIFDs caused by non‐Aspergillus moulds and three cases of probable pulmonary bIFDs were documented during the neutropenic phase after induction/consolidation chemotherapy for acute leukaemia. Colonisation with Candida spp. was documented in 51% of the patients with none of the isolates being in vitro micafungin resistant. Compared to a historical control, receiving primary prophylaxis with posaconazole micafungin is at least as effective in preventing IFD. In both cohorts, bIFDs were exclusively caused by emerging pathogens with a highly preserved in vitro sensitivity to amphotericin B.
Characterisation of patient encounters in community pharmacies (with special focus on self-medication)
Authors: De Bolle Leen , Mehuys Els , Christiaens Thierry , Van Tongelen Inge , Remon Jean-Paul , Boussery Koen
Published: August 2014

Objectives

To characterise patient encounters during routine drug dispensing in community pharmacies.

Methods

Cross-sectional survey in community pharmacies (Belgium).

Key findings

Fifty-four per cent of all encounters (N = 1650) concerned patients carrying a prescription, of which 39% were prescriptions for new medication and 61% were repeat prescriptions. In 62% of all encounters, patients asked for non-prescribed medication. Almost one-third of self-medication requests related to special patient populations (mainly children and elderly).

Conclusions

Many encounters related to self-medication, and a substantial number of these self-medication requests concerned vulnerable patient populations.
Can frailty predict complicated care needs and length of stay?
Authors: Rose M. , Pan H. , Levinson M. R. , Staples M.
Published: August 2014

The Reported Edmonton Frail Scale was used to describe the prevalence of frailty in an acute general medical unit. The relationship between frailty, discharge destination, mortality and length of hospital stay was explored. We found that age was associated with frailty, and frailty correlated to an increasing length of hospital stay. Significantly, frailty was associated with complexity in discharge, and this process created a longer length of hospital stay.
Anti‐mouse CD52 monoclonal antibody ameliorates intestinal epithelial barrier function in interleukin‐10 knockout mice with spontaneous chronic colitis
Authors: Wang Honggang , Dong Jianning , Shi Peiliang , Liu Jianhui , Zuo Lugen , Li Yi , Gong Jianfeng , Gu Lili , Zhao Jie , Zhang Liang , Zhang Wei , Zhu Weiming , Li Ning , Li Jieshou
Published: August 2014

Intestinal inflammation causes tight junction changes and death of epithelial cells, and plays an important role in the development of Crohn's disease (CD). CD52 monoclonal antibody (CD52 mAb) directly targets the cell surface CD52 and is effective in depleting mature lymphocytes by cytolytic effects in vivo, leading to long‐lasting changes in adaptive immunity. The aim of this study was to investigate the therapeutic effect of CD52 mAb on epithelial barrier function in animal models of IBD. Interleukin‐10 knockout mice (IL‐10−/−) of 16 weeks with established colitis were treated with CD52 mAb once a week for 2 weeks. Severity of colitis, CD4+ lymphocytes and cytokines in the lamina propria, epithelial expression of tight junction proteins, morphology of tight junctions, tumour necrosis factor‐α (TNF‐α)/TNF receptor 2 (TNFR2) mRNA expression, myosin light chain kinase (MLCK) expression and activity, as well as epithelial apoptosis in proximal colon were measured at the end of the experiment. CD52 mAb treatment effectively attenuated colitis associated with decreased lamina propria CD4+ lymphocytes and interferon‐γ/IL‐17 responses in colonic mucosa in IL‐10−/− mice. After CD52 mAb treatment, attenuation of colonic permeability, increased epithelial expression and correct localization of tight junction proteins (occludin and zona occludens protein‐1), as well as ameliorated tight junction morphology were observed in IL‐10−/− mice. CD52 mAb treatment also effectively suppressed the epithelial apoptosis, mucosa TNF‐α mRNA expression, epithelial expression of long MLCK, TNFR2 and phosphorylation of MLC. Our results indicated that anti‐CD52 therapy may inhibit TNF‐α/TNFR2‐mediated epithelial apoptosis and MLCK‐dependent tight junction permeability by depleting activated T cells in the gut mucosa.
From Supply Chains to Supply Ecosystems: Implications for Strategic Sourcing Research and Practice
Authors: Ketchen David J. , Crook T. Russell , Craighead Christopher W.
Published: August 2014

Traditionally, sourcing decisions such as what to buy and from whom to buy it were viewed as clerical in nature. Today, however, many executives view sourcing decisions as strategic and these decisions are being made from more prominent positions within firms. Indeed, over time more companies are embracing the concept of strategic sourcing—making acquisition decisions with the intent of creating value and achieving a competitive advantage. In this article, we introduce the Special Topic Forum articles on strategic sourcing and performance. Each offers important implications for strategic sourcing research and practice. An overall implication is that some traditional supply chains appear to be giving way to supply ecosystems, which represent a set of interdependent and coordinated organizations that share common adaptive challenges and that collectively shape the creation and nurturing of a sourcing base that contributes to competitive advantage and superior performance. We offer several theoretical perspectives that hold promise for explaining supply ecosystem functioning and outcomes. In terms of practice, firms need to adapt their strategic sourcing to this evolution or run the risk of being weakened.
Assessing the impact of patient self‐selection on the costs to treat latent tuberculosis infection (LTBI) with isoniazid and transitional rifampin
Authors: Fluegge Kyle R.
Published: August 2014

Rationale, aims and objectives

This article examines costs to treat latent tuberculosis infection (LTBI) in an urban clinic population and highlights the potential effectiveness of an alternative transitional treatment regimen.

Methods

Patients who experienced side effects on the gold standard of 9 months of isoniazid (9INH) were either continued on isoniazid or transitioned to 4 months of rifampin (4RIF). I use multilevel Tobit models with selection to analyse whether transitioning to 4RIF is less costly than remaining on 9INH among patients experiencing side effects.

Results

Results reveal that self‐selection is present in this clinic data. Using an ordered probit parametric selection rule to account for selection, I find transitioning patients to 4RIF costs significantly less than continuing on 9INH. This result is especially sensitive to selection: not controlling for selection demonstrates that patients transitioning to 4RIF actually cost significantly more to treat. Post hoc analysis revealed that switching to 4RIF significantly reduced the dropout probability among these patients.

Conclusion

Future work should more carefully assess the clinical attributes, including effectiveness, of treatment with 9INH and transitional 4RIF as alternative treatment for LTBI.
An investigation into the Professional Quality of Life of dietitians working in acute care caseloads: are we doing enough to look after our own?
Authors: Osland E. J.
Published: August 2014

Background

The development of compassion fatigue (CF) has been described across a variety of acute care caseloads in some health professions. The present study was undertaken to determine whether dietitians working in these caseloads also experience CF.

Methods

A voluntary, anonymous survey incorporating the Professional Quality of Life tool was developed in an online format, and was e‐mailed to dietitians working in public acute care settings.

Results

Eighty‐seven completed surveys were returned. Average rates of compassion satisfaction (CS) and burnout and low rates of secondary traumatic stress (STS) were reported. Dietitians in high‐risk workloads reported higher levels of STS than those with low‐risk workloads (χ2 = 5.4, P = 0.02). Differences in STS were found between those practising in paediatric compared to adult caseloads (χ2 = 16.6, P < 0.01). Dietitians in smaller facilities reported higher STS (χ2 = 10.6, P < 0.01) and lower CS (P = 0.05) than larger facilities. Working for >5 years as a dietitian was associated with higher rates of STS and burnout than in those working for <5 years (χ2 = 7.9, P = 0.05 and χ2 = 3.8, P = 0.05, respectively). Those who perceived greater levels of support reported lower rates of burnout (rs = −0.41, P < 0.01) and higher rates of CS (rs = 0.39, P < 0.01) than those not feeling supported. All dietitians reported undertaking self‐care practices; however, up to 24% reported practices that may represent maladaptive coping methods.

Conclusions

Although the present study suggests dietitians experience a good professional quality of life, vulnerable areas were identified, suggesting the need for additional support in some areas of dietetic practice.
APRI and FIB‐4 are good predictors of the stage of liver fibrosis in chronic hepatitis B: the Chronic Hepatitis Cohort Study (CHeCS)
Authors: Teshale E. , Lu M. , Rupp L. B. , Holmberg S. D. , Moorman A. C. , Spradling P. , Vijayadeva V. , Boscarino J. A. , Schmidt M. A. , Gordon S. C. ,   the CHeCS Investigators
Published: August 2014

We aim to determine the predictive ability of APRI, FIB‐4 and AST/ALT ratio for staging of liver fibrosis and to differentiate significant fibrosis (F2–F4) from none to minimal fibrosis (F0–F1) in chronic hepatitis B (CHB). Liver biopsy results were mapped to an F0–4 equivalent fibrosis stage. Mean APRI and FIB‐4 scores were significantly higher for each successive fibrosis level from F1 to F4 (P < 0.05). Based on optimized cut‐offs, the AUROCs in distinguishing F2–F4 from F0 to F1 were 0.81 (0.76–0.87) for APRI, 0.81 (0.75–0.86) for FIB‐4 and 0.56 (0.49–0.64) for AST/ALT ratio. APRI and FIB‐4 distinguished F2–F4 from F0 to F1 with good sensitivity and specificity and can be useful for treatment decisions and monitoring progression of fibrosis.
Endogenous concentrations, pharmacokinetics, and selected pharmacodynamic effects of a single dose of exogenous GABA in horses
Authors: Knych H. K. , Steinmetz S. J. , McKemie D. S.
Published: August 2014

The anti‐anxiety and calming effects following activation of the GABA receptor have been exploited in performance horses by administering products containing GABA. The primary goal of the study reported here was to describe endogenous concentrations of GABA in horses and the pharmacokinetics, selected pharmacodynamic effects, and CSF concentrations following administration of a GABA‐containing product. The mean (±SD) endogenous GABA level was 36.4 ± 12.5 ng/mL (n = 147). Sixteen of these horses received a single intravenous and oral dose of GABA (1650 mg). Blood, urine, and cerebrospinal fluid (n = 2) samples were collected at time 0 and at various times for up to 48 h and analyzed using LC‐MS. Plasma clearance and volume of distribution was 155.6 and 147.6 L/h and 0.154 and 7.39 L for the central and peripheral compartments, respectively. Terminal elimination half‐life was 22.1 (intravenous) and 25.1 (oral) min. Oral bioavailability was 9.81%. Urine GABA concentrations peaked rapidly returning to baseline levels by 3 h. Horses appeared behaviorally unaffected following oral administration, while sedative‐like changes following intravenous administration were transient. Heart rate was increased for 1 h postintravenous administration, and gastrointestinal sounds decreased for approximately 30 min following both intravenous and oral administration. Based on a limited number of horses and time points, exogenously administered GABA does not appear to enter the CSF to an appreciable extent.
The genomics of adaptation, divergence and speciation: a congealing theory
Authors: Tittes Silas , Kane Nolan C.
Published: August 2014

In this issue, Flaxman et al. () report the results of sophisticated whole‐genome simulations of speciation with gene flow, enhancing our understanding of the process by building on previous single‐locus, multilocus and analytical works. Their findings provide us with new insights about how genomes can diverge and the importance of statistical and chromosomal linkage in facilitating reproductive isolation. The authors characterize the conditions under which, even with high gene flow and weak divergent selection, reproductive isolation between populations can occur due to the emergent stochastic process of genomewide congealing, where numerous statistically or physically linked loci of small effect allow selection to limit effective migration rates. The initial congealing event can occur within a broad range conditions, and once initiated, the self‐reinforcing process leads to rapid divergence and ultimately two reproductively isolated populations. Flaxman et al.'s () work is a valuable contribution to our understanding of speciation with gene flow and in making a more predictive field of evolutionary genomics and speciation.
Standing and flowing: the complex origins of adaptive variation
Authors: Welch John J. , Jiggins Chris D.
Published: August 2014

A population faced with a new selection pressure can only adapt if appropriate genetic variation is available. This genetic variation might come from new mutations or from gene exchange with other populations or species, or it might already segregate in the population as standing genetic variation (which might itself have arisen from either mutation or gene flow). Understanding the relative importance of these sources of adaptive variation is a fundamental issue in evolutionary genetics (Orr & Betancourt ; Barrett & Schluter ; Gladyshev et al. ) and has practical implications for conservation, plant and animal breeding, biological control and infectious disease prevention (e.g. Robertson ; Soulé & Wilcox ; Prentis et al. ; Pennings ). In this issue of Molecular Ecology, Roesti et al. () make an important contribution to this longstanding debate.
Taxonomic revision of the humpback dolphins (Sousa spp.), and description of a new species from Australia
Authors: Jefferson Thomas A. , Rosenbaum Howard C.
Published: August 2014

The taxonomy of the humpback dolphin genus Sousa has been controversial and unsettled for centuries, but recent work indicates that there are several valid species. A review of multiple lines of evidence from skeletal morphology, external morphology, coloration, molecular genetics, and biogeography, in combination provides strong support for the recognition of four species of Sousa. These include S. teuszii (Kükenthal, 1892), a species with uniform gray coloration and a prominent dorsal hump, which is found in the Atlantic Ocean off West Africa. The species S. plumbea (G. Cuvier, 1829) has similar external appearance to S. teuszii, but has a more pointed dorsal fin. It occurs in the Indian Ocean from South Africa to Myanmar (Burma). The original taxon, S. chinensis (Osbeck, 1765), is reserved for the species that has a larger dorsal fin with no prominent hump, and largely white adult coloration. It ranges from eastern India to central China and throughout Southeast Asia. Finally, we describe a new species of Sousa, the Australian humpback dolphin, which occurs in the waters of the Sahul Shelf from northern Australia to southern New Guinea. It has a lower dorsal fin, more extensive dark color on the body, and a dorsal “cape.” It is separated from the Indo‐Pacific humpback dolphin by a wide distributional gap that coincides with Wallace's Line.
Manipulation of MKS1 gene expression affects Kalanchoë blossfeldiana and Petunia hybrida phenotypes
Authors: Gargul Joanna Maria , Mibus Heiko , Serek Margrethe
Published: August 2014

The establishment of alternative methods to chemical treatments for growth retardation and pathogen protection in ornamental plant production has become a major goal in recent breeding programmes. This study evaluates the effect of manipulating MAP kinase 4 nuclear substrate 1 (MKS1) expression in Kalanchoë blossfeldiana and Petunia hybrida. The Arabidopsis thaliana MKS1 gene was overexpressed in both species via Agrobacterium‐mediated transformation, resulting in dwarfed phenotypes and delayed flowering in both species and increased tolerance to Pseudomonas syringae pv. tomato in transgenic Petunia plants. The lengths of the stems and internodes were decreased, while the number of nodes in the transgenic plants was similar to that of the control plants in both species. The transgenic Kalanchoë flowers had an increased anthocyanin concentration, and the length of the inflorescence stem was decreased. The morphology of transgenic Petunia flowers was not altered. The results of the Pseudomonas syringae tolerance test showed that Petunia plants with one copy of the transgene reacted similarly to the nontransgenic control plants; however, plants with four copies of the transgene exhibited considerably higher tolerance to bacterial attack. Transgene integration and expression was determined by Southern blot hybridization and RT‐PCR analyses. MKS1 in wild‐type Petunia plants was down‐regulated through a virus‐induced gene silencing (VIGS) method using tobacco rattle virus vectors. There were no significant phenotypic differences between the plants with silenced MKS1 genes and the controls. The relative concentration of the MKS1 transcript in VIGS‐treated plants was estimated by quantitative RT‐PCR.
Swing Voting due to Smartvote Use? Evidence from the 2011 Swiss Federal Elections
Authors: Pianzola Joëlle
Published: August 2014

Almost every fifth voter in Switzerland visited the Voting Advice Application (VAA) smartvote prior to casting a ballot in the 2011 Swiss federal elections. Surveys among users reveal that the web application led voters to discover suitable candidates or parties which they previously would not have considered. The subsequent question therefore is whether the VAA initiates a change in party choice among voters. In this paper, we examine whether voters who used smartvote were more likely to swing vote in the 2011 elections than non‐users. Moreover, we take a look at which parties might have benefited from a voter flow among smartvote users. We employ both selection models and propensity score matching for tracing the causal effect of smartvote use on party choice. According to our results, smartvote users were significantly more likely to swing vote in the elections. Voter migration among smartvote users was most prominent towards the Green Liberal Party, one of the two major winners of the 2011 Swiss federal elections.
The Least Penalty Optimization Prioritization Operators for the Analytic Hierarchy Process: A Revised Case of Medical Decision Problem of Organ Transplantation
Authors: Yuen Kevin Kam Fung
Published: August 2014

The Analytic Hierarchy Process (AHP) is one of the popular methods to support human decision making. Prioritization method leading to the possibility of rank reversal is still one of the unsettled issues of the AHP, although many applications of this method have been made. In this study, 10 important prioritization methods are reviewed and compared. To evaluate the fitness of the prioritization operators (POs), on the basis of existing PO measurement criteria, this research proposes the Root Mean Penalty Weighted Square Variance (RMPWSV) as a reasonable measurement criterion. Graphical solution demonstrates the computational concept for the RMPWSV. On the basis of the RMPWSV, two Least Penalty Optimization (LPO) POs are proposed as the new perspectives for solving the prioritization problems: Least Product of Penalty and Direct Squares (LPPDS) and Least Product of Penalty and Weighted Squares (LPPWS). The comprehensive numerical analyses verify that LPPDS is the fittest PO with respect to the RMPWSV. To demonstrate improvement of the proposed method, a medical decision problem for organ transplantation is revised by using 11 developed POs and two proposed POs with respect to RMPWSV measurement. LPPDS is the ideal PO, instead of Eigenvector method, to generate a priority vector for a decision problem in various fields, such as social science, politics, business, finance, medical treatment, resource management, and engineering management.
A Framework for Space Systems Architecture under Stakeholder Objectives Ambiguity
Authors: Golkar Alessandro , Crawley Edward F.
Published: August 2014

Matching high ambitions with scarce resources is one of the primary challenges of aerospace and other industries concerned with the development of unprecedented infrastructures, on par with the technical challenges associated with developing new technology. Stakeholder objectives are often unclear due to highly exploratory business cases. Further ambiguity emerges from disagreement between stakeholders and decision makers called to formulate scientific, technological and policy requirements for new systems.

This paper develops a structured approach, called the Delphi‐based Systems Architecting Framework (DB‐SAF), which has been conceived to develop recommendations to system architects concerned with the design of unprecedented large infrastructures for which objectives are ambiguous or unclear.

The objectives of DB‐SAF are to identify sources of ambiguity in the value proposition of a system architecture and the associated trade‐space exploration, characterize and model sources of ambiguity, and assess the impact of requirement ambiguities on the architectural trade space.

The proposed systems architecting approach is demonstrated in this paper through the assessment of a robotic Mars Sample Return Campaign, which serves as a test bed case study to describe the proposed methodology and to discuss its extension to other fields of engineering.

The proposed framework integrates methods from systems engineering, computational systems architecting, multidisciplinary systems design and optimization, uncertainty modeling, utility theory, and social science research. It allows decision makers to visualize an architectural synthesis of aerospace systems, understanding adverse impacts of ambiguity, and supporting negotiations among stakeholders for efficient compromise in systems architecting.
Re-Designing Annular Combustor of APU for Better Air Management and Spray Development
Authors: Čížek Petr , Jícha Miroslav
Published: August 2014

The paper will deal with a study performed using CFD code StarCD to re-design a small annular combustor of an Auxiliary Power Unit fueled with kerosene. The current design suffers from a very high CO content due to a very rich primary zone and incomplete combustion of droplets. This is mainly due to an in-appropriate air management in the combustor and atomization quality. The fuel spray is of a conical shape that is not very suited to the narrow annular space. Some of droplets fly to the near-wall cooling zone, which results in the high CO content. Some of droplets fly far to the end of the combustor. We don’t encounter two typical toroidal vortexes in front of the injector. The task is to re-design both cooling air holes and the arrangement of the injector so to increase the residence time of the droplets inside the primary zone of the combustor. This will be shown could be reached by a better management of the air in the primary zone and by changing the arrangement of the injector.
The Gas Turbine Test Facility in the Information Age
Authors: Patterson Grant T. , Dorman C. Edward , Sloan W. R.
Published: August 2014

The Arnold Engineering Development Center (AEDC) must supply test data and test results to a geographically diverse customer base. The rapid expansion of communications technology has reshaped the landscape of how this data and information are transmitted to gas turbine manufacturers whose products are tested at AEDC. This paper will discuss the development of the communication networks for the transmittal of engine test data and information in near real-time. Past, present and future communication capabilities will be discussed. Topics will include the communication networks, the communication protocol, transmission security, network infrastructure, computers and storage devices of the overall data management and transmission system. Finally the AEDC Integrated Test Information System (ITIS) will be discussed. ITIS takes advantage of the latest technologies in communications networks, web-based communication, information/data fusion and the archiving of test data, metadata and information.
Propulsion System Integration of Turboprop Aircraft for Basic Trainer
Authors: Kong Changduk
Published: August 2014

The propulsion system integration of a turboprop aircraft, which has been developed for the basic trainer, was performed. The proper turboprop engine was selected among worldwide existing engines by the specific developed engine selection technique and trade-off studies such as customer’s request for operational capability (ROC), propulsion system parameters, performance analysis with engine installed effects, future growth potential, integrated logistic support (ILS), maintainability, interfaces with the airframe, etc. The chin type air inlet with the plenum chamber was designed in consideration of the inclined configuration to minimize the propeller swirl effect, the inertial separation bypass device to reduce FOD, and the super-ellipse and NACA-1 profile lip to maximize the ram recovery. The air inlet was analyzed by a higher-order source panel method considering propeller wake.

The exhaust duct was designed through internal cross-section area determination to maximize the cruising power as well as external configuration to maximize the effective power, to minimize the aerodynamic drag and to minimize the cockpit contamination by the exhaust gas. The proper oil cooler for the selected turboprop engine was determined with cooling requirements and the oil cooling inlet duct with NACA configuration was designed.

The test of the propulsion system including the installation performance test with the effects of the air inlet, the exhaust duct, the propeller and the nose fuselage configuration was performed in the test cell.
An Evaluation of Engine Faults Diagnostics Using Artificial Neural Networks
Authors: Lu Pong-Jeu , Zhang Ming-Chuan , Hsu Tzu-Cheng , Zhang Jin
Published: August 2014

Application of artificial neural network (ANN)-based method to perform engine condition monitoring and fault diagnosis is evaluated. Back-propagation, feedforward neural nets are employed for constructing engine diagnostic networks. Noise-contained training and testing data are generated using an influence coefficient matrix and the data scatters. The results indicate that under high-level noise conditions ANN fault diagnosis can only achieve a 50–60% success rate. For situations where sensor scatters are comparable to those of the normal engine operation, the success rates for both 4-input and 8-input ANN diagnoses achieve high scores which satisfy the minimum 90% requirement. It is surprising to find that the success rate of the 4-input diagnosis is almost as good as that of the 8-input. Although the ANN-based method possesses certain capability in resisting the influence of input noise, it is found that a preprocessor that can perform sensor data validation is of paramount importance. Auto-associative neural network (AANN) is introduced to reduce the noise level contained. It is shown that the noise can be greatly filtered to result in a higher success rate of diagnosis. This AANN data validation preprocessor can also serve as an instant trend detector which greatly improves the current smoothing methods in trend detection. It is concluded that ANN-based fault diagnostic method is of great potential for future use. However, further investigations using actual engine data have to be done to validate the present findings.
Advanced Diagnostic and Prognostic Technologies for Gas Turbine Engine Risk Assessment
Authors: Roemer Michael J. , Kacprzynski Gregory J.
Published: August 2014

Real-time, integrated health monitoring of gas turbine engines that can detect, classify, and predict developing engine faults is critical to reducing operating and maintenance costs while optimizing the life of critical engine components. Statistical-based anomaly detection algorithms, fault pattern recognition techniques and advanced probabilistic models for diagnosing structural, performance and vibration related faults and degradation can now be developed for real-time monitoring environments. Integration and implementation of these advanced technologies presents a great opportunity to significantly enhance current engine health monitoring capabilities and risk management practices.

This paper describes some novel diagnostic and prognostic technologies for dedicated, real-time sensor analysis, performance anomaly detection and diagnosis, vibration fault detection, and component prognostics. The technologies have been developed for gas turbine engine health monitoring and prediction applications which includes an array of intelligent algorithms for assessing the total ‘health’ of an engine, both mechanically and thermodynamically. This includes the ability to account for uncertainties from engine transient conditions, random measurement fluctuations and modeling errors associated with model-based diagnostic and prognostic procedures. The implementation of probabilistic methods in the diagnostic and prognostic methodology is critical to accommodating for these types of uncertainties.
Identifying Faults in the Variable Geometry System of a Gas Turbine Compressor
Authors: Tsalavoutas A. , Mathioudakis K. , Stamatis A. , Smith M.
Published: August 2014

The influence of faults in the variable geometry (variable stator vanes) system of a multistage axial compressor, on the performance of an industrial gas turbine is investigated. An experimental investigation has been conducted, by implanting such faults into an operating gas turbine. The faults examined are individual stator vane mistuning of different magnitude, and located at different stages.

Fault identification is based on the aerothermodynamic measurement data and is achieved by employing two different techniques, namely adaptive performance modelling and monitoring the circumferential distribution of the turbine exit temperature. It is observed that the deviations of the health indices produced by an adaptive performance model, form patterns that can be used to identify the faults. The patterns characterize both the kind and the magnitude of the fault. On the other hand, the turbine exit temperature profile is also influenced and its change can be used as additional information, to increase the confidence level of the diagnosis (contrary to customary practice, which expects temperatures profiles to reflect only burner or turbine malfunctions).
An Object-Oriented Program for the Dynamic Simulation of Gas Turbines
Authors: Agresti M. , Camporeale S. M. , Fortunato B.
Published: August 2014

An object-oriented program for the dynamic simulation of gas turbines has been developed using Matlab-Simulink® utilities. The advantages given by the object-oriented program are the flexibility and the user-friendly interface. The components of the gas turbine are modeled as blocks that can be assembled like an engineering drawing in which the connections between two elements represent either a mechanical power transfer or a fluid transfer. In a fluid-type connection the data regarding the fluid composition, the thermodynamic properties and the fluid velocity are simultaneously transferred. A library of gas turbine components has been developed: each component appears as a block that can be placed into the drawing by means of click-and-drag operations.

In order to obtain an accurate description of the physical processes characterizing the gas turbine, the components are described by a set of non-linear algebraic equations and ordinary differential equations. Each component block is created using the graphical programming tools of Simulink, following a block diagram approach. Specific blocks have been created for the evaluation of the thermodinamic properties of the working fluids. The paper provides the description of the mathematical model adopted for the simulation and the some examples of the Matlab-Simulink formulation adopted for implementing the model. The accuracy of the program has been verified considering test cases for which experimental data are available in the public literature.

The computational times, tested for the transients of a single-shaft and a double-shaft gas turbine, resulted to be very short, even making use of a personal computer.
Fuzzy Fuel Flow Selection Logic for a Real Time Embedded Full Authority Digital Engine Control
Authors: Martucci Angelo , Volponi Allan J.
Published: August 2014

The control logic of the modern Full Authority Digital Engine Control (FADEC) is comprised of many control loops, each of which has a specific purpose. Typical control loops include (but are not limited to) a high or low rotor speed governor, an Acceleration and Deceleration loop, and various limiting loops for temperature, speed, fuel flow, and rate of change of fuel flow. The logic that determines which of these loops is “in control” at any particular time has a history of being very simplistic. This Selection Logic is usually nothing more that a cascade of minimum and maximum selection logic gates. Since this logic is so simplistic, the control engineer often has to “fine tune” the compensator design for each loop, in order to achieve proper performance.

The purpose of this paper is to a present a means of achieving a selection logic design based on Fuzzy Logic principles. Hereafter, this shall be referred to as a Fuzzy Fuel Flow Selector. The paper provides a brief overview of the most typical architecture for real time embedded FADEC control logic, rule development for the Fuzzy Fuel Flow Selector, and a realistic implementation of the Fuzzy Fuel Flow Selector. Also provided is a typical application that is used to contrast the performance between traditional selection logic and the Fuzzy Fuel Flow Selector. An overview of the Fuzzy Logic process is also included for completeness.
Understanding Machinery Management — Using Machine Condition and Process Information for Maximum Benefit
Authors: Harker Roger G.
Published: August 2014

The use of machinery protection systems is well-established in industry. These systems shut down a machine or return it to a safe or nondestructive mode of operation without human intervention. Protection systems are used to ensure personnel safety, prevent or minimize machine damage, and limit environmental impact. While these are substantial benefits, machinery protection remains inherently reactive, and the approach is still necessary, but no longer sufficient in today’s economic environment. Machinery management is increasingly recognized for its ability to indicate machinery condition before a protection system’s alarm levels are exceeded. By providing an early warning of what is happening with the machine, proactive decisions can be made about how machinery assets are run and how they affect the plant. Machinery management requires the correlation of critical process data with vibration and position data. It allows event correlation and effective root cause analysis. Information resulting from effective machinery management is actionable because it results from continuous online audits of machinery, and indicates when action is required and how best to take it. Machinery management helps answer key questions, such as: How long can this machine run? Can the process be adjusted to extend the operation and avoid a shutdown? If you want to proactively manage machinery and optimize machinery performance along with the process, you must have an effective machinery management program.

This paper explores the practice of machinery management, including what it is, what is considered “best practice,” and what the resulting benefits are.
Suppression of Dynamic Combustion Instabilities by Passive and Active Means
Authors: Berenbrink Peter , Hoffmann Stefan
Published: August 2014

In the gas turbine industry, lean premixed combustion is a state-of-the-art technology for the reduction of NOx emissions. Due to the ever increasing reaction densities and turbine inlet temperatures in modern gas turbines, the combustors reveal an increased tendency to form dynamic combustion instabilities.

This paper reports on the use of passive and active methods for the suppression of combustion oscillations in heavy-duty gas turbines featuring lean premixed combustion:

Modifications of the burner exit nozzle are implemented in order to avoid fluiddynamic feedback and to change the acoustic behavior of the flame.

An asymmetric circumferential distribution of flames with different thermoacoustic responses serves to avoid or at least attenuate the self-excitation within the combustor in multiburner systems.

In some applications, these methods are successfully coupled with an active system for the suppression of combustion instabilities (AIC) to further extend the operation envelope.

Field demonstrations in different Siemens gas turbines serve to demonstrate the benefit and flexibility of these measures for practical gas turbine combustion systems.
Influence of the Combustor Aerodynamics on Combustion Instabilities From Equivalence Ratio Fluctuations
Authors: Sattelmayer Thomas
Published: August 2014

Gas turbine combustors are often susceptible to self excited oscillations, which lead to unacceptable levels of pressure, velocity and heat release fluctuations. Although instabilities can occur in systems with locally constant equivalence ratio, it is very important to take into account the influence of equivalence ratio fluctuations, which are generated in the fuel air mixer in the unstable case. These fluctuations are convected into the flame and lead to an additional mechanism for the generation of heat release fluctuations. Moreover, entropy waves are produced in the flame, which travel through the combustor and generate additional pressure waves during the acceleration of the flow at the combustor exit.

To date, available theories use the physically unrealistic assumption that the equivalence ratio waves as well as the entropy waves are convected downstream without any spatial dispersion due to the combustor aerodynamics. An analytical approach is presented, which allows to take the spatial dispersion into consideration. For that purpose, the response of the burner and the combustor to an equivalence ratio impulse or an entropy impulse is calculated using the Laplace transformation and a more general transfer function for harmonic waves is derived. The obtained expression has three parameters, which represent the influence of the burner or the combustor aerodynamics, respectively. This equation can be used in numerical codes, which represent the combustion system through a network of acoustic multiports, if the equivalence ratio and the entropy are added to the vector of variables considered. The parameters required for the dynamic combustor model can be deduced from a detailed CFD analysis of the combustor flow in case of the application of the theory to a particular combustor design.

As an example, a simple model combustor is used to demonstrate the application of the theory. It is highlighted how the spatial dispersion of the equivalence ratio and entropy fluctuations can be included in the stability analysis. The calculated examples reveal that the influence of both variables on the generation of instabilities is highly overpredicted if the spatial dispersion is not taken into account. Furthermore, it can be deduced from the study, that burner and combustor designs with a wide range of convective time scales have advantages with respect to the stability of the combustor.
Pressure Effect on NOx and CO Emissions in Industrial Gas Turbines
Authors: Bhargava Anuj , Kendrick Donald W. , Colket Meredith B. , Sowa William A. , Casleton Kent H. , Maloney Daniel J.
Published: August 2014

In order to determine the effect of pressure on emissions and stability limit, an experimental and modeling study has been performed jointly by UTRC and DOE-FETC. Experiments have been performed at lean conditions in 100–400 psi range with two different nozzles. Measured NOx and CO concentrations have been modeled with a PSR Network using detailed chemistry. Good agreement between the data and model predictions over a wide range of conditions indicate the consistency and reliability of the measured data and validity of the modeling approach.

Experiments were conducted at the DOE-FETC facility in Morgantown. A simple refractory combustor liner with a fuel-air-premixing nozzle was used to map stability margins, emission levels of NOx, CO and combustion efficiency. Each experimental nozzle had a centerbody and wall pilot for flame stabilization. Data was collected at four different pressures of 100, 200, 300 and 400 psi, and at different diffusion pilot and moisture levels. The premixing nozzle hardware could be easily lit and operated over a broad range of flame temperatures with minimal combustion generated noise. Two different nozzles designed at UTRC were used to determine pressure and nozzle effects.

Computations were made for comparison with the experiments. GRI Mech 2.11 kinetics and thermodynamic database was used for modeling the flame chemistry. A Perfectly Stirred Reactor (PSR) network code developed internally at UTRC was used to create a network of PSRs to simulate the flame and combustor. A total of 10 to 15 reactors were used in the network. Residence time varied with the flow rates (air was fixed while fuel flow rate was varied in order to obtain the required equivalence ratio, ϕ).

Good agreement between the measured and modeled NOx (5–10%) was obtained, but the agreement for CO (model predictions are higher by 30–50%) was not as good as for NOx. The experimental data and the modeling predictions indicate that the NOx emission functionality with pressure is dependent on both equivalence ratio and absolute pressure. The CO levels tend to go down with increase in pressure as P−0.5, at different equivalence ratios, consistent with an equilibrium analysis.