bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modal H∞-Control in the Context of a Rotor Being Subject to Unbalance Excitation and Gyroscopic Effect
Authors: Schittenhelm Rudolf Sebastian , Riemann Bernd , Rinderknecht Stephan 
Published: November 2013

H∞-optimal controllers are designed for a rotor being subject to unbalance excitation and gyroscopic effect. The system possesses two unbalance-induced resonances within its operating range. The presence of gyroscopic effect is challenging for linear time invariant controller design because of the associated dependence of the system dynamics on the rotational frequency of the rotor. Controllers thus have to be robust against deviation of the actual system behavior from the controller design point model.
For vibration control purposes, there are two piezoelectric actuators installed in one of the two supports of the rotor. The signals of four inductive sensors measuring the displacements of the two discs of the rotor are used for controller design.
In this article, H∞-optimal controllers are designed on the basis of input and output weighting as well as weighting of modal degrees of freedom and modal excitations. It is shown that superior control performance is achieved using modal weighting since a more accurate problem description of rotors excited by unbalance is incorporated in controller design. Results in this article show furthermore that it is possible to design well performing H∞-optimal controllers for a gyroscopic rotor by means of iterative controller design without taking model uncertainty directly into account via weighting of certain FRFs of the system to be controlled.
Rotor Drop Simulations and Validation With Focus on Internal Contact Mechanisms of Hybrid Ball Bearings
Authors: Anders Jens , Leslie Peter , Stacke Lars-Erik 
Published: November 2013

Active Magnetic Bearings technology is becoming more and more a standard in Oil and Gas turbo machinery. Touchdown bearings are an important element of all machines levitated by magnetic bearings. Frequently implemented as hybrid ball bearings, they constitute the only mechanical link between the rotor spinning at high peripheral speed and the stator. Since both sides carry fragile parts, any uncontrolled contact must be avoided.
Extensive testing has been done in industry. When unplanned down-time would have a high system impact or when repair options are limited (upstream equipment, subsea operation), elaborate testing campaigns are common. A complement, if not an alternative, are computer based transient rotor drop simulations. They allow reducing uncertainties and help qualifying designs. In most cases, simulations use rotor dynamics models combined with contact models allowing an estimation of shaft behavior during a drop. We present a new approach for transient rotor drop simulations, where detailed calculation of the interior ball bearing mechanics is at the center of the model. This is possible by using a multiple-bodies simulation code, which was initially developed for pure ball bearing calculations and implements contact models including lubrication, wear, and geometry imperfections. Here, the same code is used to model entire shaft systems, associated with preloaded touchdown bearings. This technique allows not only to understand and to analyze failure patterns that determine bearing lifetime (contact stress, heat, and deformation), but also to take into account interactions of the bearing itself with the rest of the system.
After a feasibility study for validating the capability of simulating rotor drops, three models were realized for three different types of machines of increasing complexity that were all validated by actual drop tests. The last model is a supercritical horizontal shaft system (200kg) representing an actual Oil and Gas application in reduced scale. Simulated shaft behavior was successfully compared to drop test recordings. The output was analyzed for internal bearing mechanics (contact pressures and contact angle, sliding or rolling friction) and could be correlated with evidence found on the bearings from the drop tests.
Modeling Off-Design and Part-Load Performance of Supercritical Carbon Dioxide Power Cycles
Authors: Dyreby John J. , Klein Sanford A. , Nellis Gregory F. , Reindl Douglas T. 
Published: November 2013

Continuing efforts to increase the efficiency of utility-scale electricity generation has resulted in considerable interest in Brayton cycles operating with supercritical carbon dioxide (S-CO2). One of the advantages of S-CO2 Brayton cycles, compared to the more traditional steam Rankine cycle, is that equal or greater thermal efficiencies can be realized using significantly smaller turbomachinery. Another advantage is that heat rejection is not limited by the saturation temperature of the working fluid, facilitating dry cooling of the cycle (i.e., the use of ambient air as the sole heat rejection medium). While dry cooling is especially advantageous for power generation in arid climates, the reduction in water consumption at any location is of growing interest due to likely tighter environmental regulations being enacted in the future. Daily and seasonal weather variations coupled with electric load variations means the plant will operate away from its design point the majority of the year. Models capable of predicting the off-design and part-load performance of S-CO2 power cycles are necessary for evaluating cycle configurations and turbomachinery designs.
This paper presents a flexible modeling methodology capable of predicting the steady state performance of various S-CO2 cycle configurations for both design and off-design ambient conditions, including part-load plant operation. The models assume supercritical CO2 as the working fluid for both a simple recuperated Brayton cycle and a more complex recompression Brayton cycle.
Gas Turbine Engine Health Management: Past, Present and Future Trends
Authors: Volponi Allan J. 
Published: November 2013

Engine diagnostic practices are as old as the gas turbine itself. Monitoring and analysis methods have progressed in sophistication over the past 6 decades as the gas turbine evolved in form and complexity. While much of what will be presented here may equally apply to both stationary power plants and aero-engines, the emphasis will be on aero propulsion.
Beginning with primarily empirical methods centering around monitoring the mechanical integrity of the machine, the evolution of engine diagnostics has benefited from advances in sensing, electronic monitoring devices, increased fidelity in engine modeling and analytical methods. The primary motivation in this development is, not surprisingly, cost. The ever increasing cost of fuel, engine prices, spare parts, maintenance and overhaul, all contribute to the cost of an engine over its entire life cycle. Diagnostics can be viewed as a means to mitigate risk in decisions that impact operational integrity. This can have a profound impact on safety, such as In-Flight Shut Downs (IFSD) for aero applications, (outages for land based applications) and economic impact caused by Unscheduled Engine Removals (UERs), part life, maintenance and overhaul and the overall logistics of maintaining an aircraft fleet or power generation plants.
This paper will review some of the methods used in the preceding decades to address these issues, their evolution to current practices and some future trends. While several different monitoring and diagnostic systems will be addressed, the emphasis in this paper will be centered on those dealing with the aero-thermodynamic performance of the engine.
A Tool for the Structural Integrity Assessment of Turbine Disks: Probabilistic and Numerical Background
Authors: Madia M. , Beretta S. , Foletti S. , Cavalleri E. A. 
Published: November 2013

Rotor disks for gas turbines are heavy components and are usually designed following a safe-life approach, where the low-cycle fatigue analysis is carried out referring to design life curves with suitable probabilistic margins. However, in the case of such a heavy component there is the possibility of rare occurrence of undetected defects or, better, the need to identify the defect acceptability for the different rotor regions (considering stress, temperature, mission profile).
In order to carry out such calculations for a turbine rotor disk a software named AStrID (Assessment of the Structural Integrity of Disks) has been developed in close cooperation between Politecnico di Milano and Ansaldo Energia (AEN). This paper summarizes its background and some of the relevant features.
A Retrograde Trafficking Inhibitor of Ricin and Shiga-Like Toxins Inhibits Infection of Cells by Human and Monkey Polyomaviruses
Authors: Nelson Christian D. S. , Carney Dan W. , Derdowski Aaron , Lipovsky Alex , Gee Gretchen V. , O’Hara Bethany , Williard Paul , DiMaio Daniel , Sello Jason K. , Atwood Walter J. 
Published: November 2013

ABSTRACT

Polyomaviruses are ubiquitous pathogens that cause severe disease in immunocompromised individuals. JC polyomavirus (JCPyV) is the causative agent of the fatal demyelinating disease progressive multifocal leukoencephalopathy (PML), whereas BK polyomavirus (BKPyV) causes polyomavirus-induced nephropathy and hemorrhagic cystitis. Vaccines or antiviral therapies targeting these viruses do not exist, and treatments focus on reducing the underlying causes of immunosuppression. We demonstrate that retro-2
cycl
, an inhibitor of ricin and Shiga-like toxins (SLTs), inhibits infection by JCPyV, BKPyV, and simian virus 40. Retro-2
cycl
inhibits retrograde transport of polyomaviruses to the endoplasmic reticulum, a step necessary for productive infection. Retro-2
cycl
likely inhibits polyomaviruses in a way similar to its ricin and SLT inhibition, suggesting an overlap in the cellular host factors used by bacterial toxins and polyomaviruses. This work establishes retro-2
cycl
as a potential antiviral therapy that broadly inhibits polyomaviruses and possibly other pathogens that use retrograde trafficking.

IMPORTANCE
The human polyomaviruses JC polyomavirus (JCPyV) and BK polyomavirus (BKPyV) cause rare but severe diseases in individuals with reduced immune function. During immunosuppression, JCPyV disseminates from the kidney to the central nervous system and destroys oligodendrocytes, resulting in the fatal disease progressive multifocal leukoencephalopathy. Kidney transplant recipients are at increased risk of BKPyV-induced nephropathy, which results in kidney necrosis and loss of the transplanted organ. There are currently no effective therapies for JCPyV and BKPyV. We show that a small molecule named retro-2
cycl
protects cells from infection with JCPyV and BKPyV by inhibiting intracellular viral transport. Retro-2
cycl
treatment reduces viral spreading in already established infections and may therefore be able to control infection in affected patients. Further optimization of retro-2
cycl
may result in the development of an effective antiviral therapy directed toward pathogens that use retrograde trafficking to infect their hosts.
Morphologic and hemodynamic analysis of paraclinoid aneurysms: ruptured versus unruptured
Authors: Liu Jian , Xiang Jianping , Zhang Ying , Wang Yang , Li Haiyun , Meng Hui , Yang Xinjian 
Published: November 2013

BackgroundIn order to determine the risk factors related to aneurysm rupture, we studied the aneurysms at the paraclinoid segment of the internal carotid artery by applying morphologic and hemodynamic numerical analyzes.Methods107 patients with 110 paraclinoid aneurysms (26 ruptured, 84 unruptured) were analyzed using computational fluid dynamics based on patient-specific three-dimensional geometrical models. A series of morphologic and hemodynamic parameters were evaluated to find the potential indicators of aneurysm rupture.ResultsAneurysms with an irregular shape accounted for 23.1% of the ruptured group and only 8.3% of the unruptured group. The difference was statistically significant (p=0.042, χ2test). Ruptured paraclinoid aneurysms were found to be significantly smaller than unruptured aneurysms (p=0.041), which is different from the results of most previous studies. Energy loss (EL) and inflow concentration showed a level of statistical significance to assess the risk of rupture in paraclinoid aneurysms. By multivariate logistic regression analysis, aneurysm shape (regular or irregular), EL and inflow concentration were retained as independently significant parameters. The odds of rupture were increased by 1.65 times for a 10% increase in EL, by 4.88 times for an aneurysm with an irregular shape and by 2.91 times for an aneurysm with concentrated inflow jet.ConclusionsIrregular shape, larger EL and concentrated inflow jet were independently associated with the rupture status of paraclinoid aneurysms. These findings need to be further confirmed based on large multicenter and multipopulation data.
Tumor Hypoxia Does Not Drive Differentiation of Tumor-Associated Macrophages but Rather Fine-Tunes the M2-like Macrophage Population
Authors: Laoui Damya , Van Overmeire Eva , Di Conza Giusy , Aldeni Chiara , Keirsse Jiri , Morias Yannick , Movahedi Kiavash , Houbracken Isabelle , Schouppe Elio , Elkrim Yvon , Karroum Oussama , Jordan Bénédicte , Carmeliet Peter , Gysemans Conny , De Baetselier Patrick , Mazzone Massimiliano , Van Ginderachter Jo A. 
Published: November 2013

Abstract
Tumor-associated macrophages (TAM) are exposed to multiple microenvironmental cues in tumors, which collaborate to endow these cells with protumoral activities. Hypoxia, caused by an imbalance in oxygen supply and demand because of a poorly organized vasculature, is often a prominent feature in solid tumors. However, to what extent tumor hypoxia regulates the TAM phenotype in vivo is unknown. Here, we show that the myeloid infiltrate in mouse lung carcinoma tumors encompasses two morphologically distinct CD11bhiF4/80hiLy6Clo TAM subsets, designated as MHC-IIlo and MHC-IIhi TAM, both of which were derived from tumor-infiltrating Ly6Chi monocytes. MHC-IIlo TAM express higher levels of prototypical M2 markers and reside in more hypoxic regions. Consequently, MHC-IIlo TAM contain higher mRNA levels for hypoxia-regulated genes than their MHC-IIhi counterparts. To assess the in vivo role of hypoxia on these TAM features, cancer cells were inoculated in prolyl hydroxylase domain 2 (PHD2)-haplodeficient mice, resulting in better-oxygenated tumors. Interestingly, reduced tumor hypoxia did not alter the relative abundance of TAM subsets nor their M2 marker expression, but specifically lowered hypoxia-sensitive gene expression and angiogenic activity in the MHC-IIlo TAM subset. The same observation in PHD2+/+→ PHD2+/− bone marrow chimeras also suggests organization of a better-oxygenized microenvironment. Together, our results show that hypoxia is not a major driver of TAM subset differentiation, but rather specifically fine-tunes the phenotype of M2-like MHC-IIlo TAM. Cancer Res; 74(1); 24–30. ©2013 AACR.
Personal History of Diabetes, Genetic Susceptibility to Diabetes, and Risk of Brain Glioma: A Pooled Analysis of Observational Studies
Authors: Kitahara Cari M. , Linet Martha S. , Brenner Alina V. , Wang Sophia S. , Melin Beatrice S. , Wang Zhaoming , Inskip Peter D. , Freeman Laura E. Beane , Braganza Melissa Z. , Carreón Tania , Feychting Maria , Gaziano J. Michael , Peters Ulrike , Purdue Mark P. , Ruder Avima M. , Sesso Howard D. , Shu Xiao-Ou , Waters Martha A. , White Emily , Zheng Wei , Hoover Robert N. , Fraumeni Joseph F. , Chatterjee Nilanjan , Yeager Meredith , Chanock Stephen J. , Hartge Patricia , Rajaraman Preetha 
Published: November 2013

Abstract
Background: Brain glioma is a relatively rare and fatal malignancy in adulthood with few known risk factors. Some observational studies have reported inverse associations between diabetes and subsequent glioma risk, but possible mechanisms are unclear.
Methods: We conducted a pooled analysis of original data from five nested case–control studies and two case–control studies from the United States and China that included 962 glioma cases and 2,195 controls. We examined self-reported diabetes history in relation to glioma risk, as well as effect modification by seven glioma risk-associated single-nucleotide polymorphisms (SNP). We also examined the associations between 13 diabetes risk-associated SNPs, identified from genome-wide association studies, and glioma risk. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariable-adjusted logistic regression models.
Results: We observed a 42% reduced risk of glioma for individuals with a history of diabetes (OR = 0.58; 95% CI, 0.40–0.84). The association did not differ by sex, study design, or after restricting to glioblastoma, the most common histological subtype. We did not observe any significant per-allele trends among the 13 diabetes-related SNPs examined in relation to glioma risk.
Conclusion: These results support an inverse association between diabetes history and glioma risk. The role of genetic susceptibility to diabetes cannot be excluded, and should be pursued in future studies together with other factors that might be responsible for the diabetes–glioma association.
Impact: These data suggest the need for studies that can evaluate, separately, the association between type 1 and type 2 diabetes and subsequent risk of adult glioma. Cancer Epidemiol Biomarkers Prev; 23(1); 47–54. ©2013 AACR.
Low Levels of Circulating Estrogen Sensitize PTEN-Null Endometrial Tumors to PARP Inhibition In Vivo
Authors: Janzen Deanna M. , Paik Daniel Y. , Rosales Miguel A. , Yep Brian , Cheng Donghui , Witte Owen N. , Kayadibi Huseyin , Ryan Christopher M. , Jung Michael E. , Faull Kym , Memarzadeh Sanaz 
Published: November 2013

Abstract
Earlier in vitro work demonstrated that PARP inhibition induces cell death in PTEN-null endometrial cancer cell lines, but the in vivo therapeutic efficacy of these agents against endometrial cancer remains unknown. Here, we test the efficacy of AZD2281 (olaparib), an oral PARP inhibitor, in the therapy of PTEN-null endometrial tumors in a preclinical endometrial cancer mouse model. Primary endometrial tumors were generated by epithelial loss of PTEN using an in vivo model. This model recapitulates epithelial-specific loss of PTEN seen in human tumors, and histologically resembles endometrioid carcinomas, the predominant subtype of human endometrial cancers. Olaparib was administered orally to tumor-bearing mice in two hormonal extremes: high or low estrogen. Olaparib treatment achieved a significant reduction in tumor size in a low estrogenic milieu. In striking contrast, no response to olaparib was seen in tumors exposed to high levels of estrogen. Two key observations were made when estrogen levels were dropped: (i) the serum concentration of olaparib was significantly increased, resulting in sustained PARP inhibition at the tumor bed; and (ii) the homologous recombination pathway was compromised, as evidenced by decreased Rad51 protein expression and function. These two mechanisms may account for the sensitization of PTEN-null tumors to olaparib with estrogen deprivation. Results of this preclinical trial suggest that orally administered PARP inhibitors in a low estrogenic hormonal milieu can effectively target PTEN-null endometrial tumors. Extension of this work to clinical trials could personalize the therapy of women afflicted with advanced endometrial cancer using well-tolerated orally administered therapeutic agents. Mol Cancer Ther; 12(12); 2917–28. ©2013 AACR.
An Investigation of the Connections among Convection, Clouds, and Climate Sensitivity in a Global Climate Model
Authors: Zhao Ming 
Published: November 2013

Abstract
This study explores connections between process-level modeling of convection and global climate model (GCM) simulated clouds and cloud feedback to global warming through a set of perturbed-physics and perturbed sea surface temperature experiments. A bulk diagnostic approach is constructed, and a set of variables is derived and demonstrated to be useful in understanding the simulated relationship. In particular, a novel bulk quantity, the convective precipitation efficiency or equivalently the convective detrainment efficiency, is proposed as a simple measure of the aggregated properties of parameterized convection important to the GCM simulated clouds. As the convective precipitation efficiency increases in the perturbed-physics experiments, both liquid and ice water path decrease, with low and middle cloud fractions diminishing at a faster rate than high cloud fractions. This asymmetry results in a large sensitivity of top-of-atmosphere net cloud radiative forcing to changes in convective precipitation efficiency in this limited set of models.
For global warming experiments, intermodel variations in the response of cloud condensate, low cloud fraction, and total cloud radiative forcing are well explained by model variations in response to total precipitation (or detrainment) efficiency. Despite significant variability, all of the perturbed-physics models produce a sizable increase in precipitation efficiency to warming. A substantial fraction of the increase is due to its convective component, which depends on the parameterization of cumulus mixing and convective microphysical processes. The increase in convective precipitation efficiency and associated change in convective cloud height distribution owing to warming explains the increased cloud feedback and climate sensitivity in recently developed Geophysical Fluid Dynamics Laboratory GCMs. The results imply that a cumulus scheme using fractional removal of condensate for precipitation and inverse calculation of the entrainment rate tends to produce a lower climate sensitivity than a scheme using threshold removal for precipitation and the entrainment rate formulated inversely dependent on convective depth.
Comparing profiles of mental disorder across birth cohorts: Results from the 2007 Australian National Survey of Mental Health and Wellbeing
Authors: Sunderland Matthew , Carragher Natacha , Buchan Heather , Batterham Philip J , Slade Tim 
Published: November 2013

Objective: To describe and compare individuals with any DSM-IV mental disorder from three different birth cohorts – young (16–34 years), middle age (35–59 years) and older age (60–85 years) – on a range of clinically relevant factors. Method: Data were derived from the 2007 Australian National Survey of Mental Health and Wellbeing. Individuals from three birth cohorts with a range of mental health and substance use disorders were identified using DSM-IV criteria and compared using regression analysis. The specific factors that were compared include: (1) type of disorder/disorders present; (2) suicidality; (3) number of co-occurring disorders; (4) levels of distress and impairment; (5) self-assessed physical and mental health; (6) presence of physical conditions; (7) size and quality of social support/network; and (8) treatment-seeking behaviour. Results: The birth cohorts differed dramatically in terms of the specific disorders that were present. The older cohort were significantly more likely to experience internalising disorders and significantly less likely to experience externalising disorders in comparison to the young cohort. The older cohort were significantly more likely to experience co-morbid physical conditions as well as lower life satisfaction, poorer self-rated physical health, increased functional impairment, and more days out of role. The younger cohort had a significantly larger peer group that they could confide in and rely on in comparison to the older cohort. Conclusions: Clinicians and researchers need to be cognisant that mental disorders manifest as highly heterogeneous constructs. The presentation of a disorder in a younger individual could be vastly different from the presentation of the same disorder in an older individual. The additional burden associated with these factors and how they apply to different birth cohorts must be taken into consideration when planning mental health services and effective treatment for the general population.