bluuebunny/crossref_metadata_2025 huggingface dataset:
An indirect method for assessing the abundance of introduced pest Myocastor coypus (Rodentia) in agricultural landscapes
Authors: Balestrieri A. , Zenato M. , Fontana E. , Vezza P. , Remonti L. , Caronni F. E. , Saino N. , Prigioni C.
Published: August 2015

Pest management requires the development of robust monitoring tools. In Italy, coypu Myocastor coypus (nutria) have been controlled since the early 1990s, but the effectiveness of these measures has never been tested. With the aim of developing a reliable and volunteer‐based method for the long‐term monitoring of coypu abundance in agricultural landscapes, we calibrated an index based on surveys for coypu paths against density estimates obtained through a standardized mark–recapture technique. Two trapping sessions were performed in winter for each of 12 1‐km long stretches of irrigation canals and watercourses using 15 baited cage traps. Trapping sessions lasted 7 days each, with a 10‐day break between sessions. Population size was assessed using three methods: Peterson–Lincoln's formula, capwire estimators and accumulation curves. Active coypu paths and five habitat variables were recorded by walking on the edge of both banks. The variables were then related to population size (y) by means of multi‐regressive models, testing for the predictive power of the selected models by leave‐one‐out cross‐validation. Multi‐regressive models included only the number of coypu paths with the best performances achieved by the model based on Peterson–Lincoln formula, supporting path count as an effective method to assess the abundance of the coypu in agricultural landscapes. Concurrently, to assess the field suitability of the indirect method, surveys for coypu paths were carried out on 122 randomly chosen 3‐km long stretches of irrigation canals and watercourses in the central part of the River Po valley (c. 15 000 km2; N Italy). The highest (>8/100 m) mean number of paths was recorded in the central part of the study area. According to the regression models, the overall number of coypu is predicted to range between 350 000 and 1 100 000, raising doubts about the effectiveness of current control measures.
Phenytoin inhibits contractions of rat gastrointestinal and portal vein smooth muscle by inhibiting calcium entry
Authors: Patejdl R. , Leroux A.‐C. , Noack T.
Published: August 2015

Background

Phenytoin is widely used as a second‐line treatment for status epilepticus. Besides its well‐known cardiac pro‐arrhythmogenicity, side effects on other organ systems have received less attention.

Methods

This study investigates the effects of phenytoin on gastrointestinal tissue function using an in vitro model of smooth muscle preparations from rats by combining registrations of pharmacological effects on mechanical contractions, electric field potentials, and dynamic intravital fluorescence microscopy.

Key Results

When added to the bathing solution at a concentration of 30 μM, phenytoin reduced the frequency of spontaneous activity significantly in antrum and portal vein preparations to 72.2 ± 36.5% (p = 0.022) and 80.7 ± 24.4% (p = 0.037) of control values, respectively. At a concentration of 100 μM, the height of spontaneous contractions declined to 9.8 ± 19.6% (p = 0.005) (antrum), 15.7 ± 28.2% (p = 0.004) (portal vein), and 31.8 ± 31.3% (p = 0.005) (colon) in comparison to the control conditions before the application of phenytoin. Depolarization triggered increases in calcium dependent fluorescence signals were reduced by 52.8 ± 39.1% (p = 0.012) The inhibition of spontaneous activity caused by phenytoin was reduced in the presence of the L‐type calcium channel agonist BAY K8644(‐).

Conclusions & Inferences

Phenytoin exerts strong inhibitory effects on the spontaneous and stimulated contractile activity of smooth muscles from both the upper and lower gastrointestinal tract. The mechanism underlying this effect is not related to the sodium channel blocking activity of phenytoin, but is rather caused by an inhibition of calcium entry through voltage dependent L‐type calcium channels. The results of this study should raise vigilance to gastrointestinal complications in patients treated with phenytoin.
Gender differences in irritable bowel syndrome: the interpersonal connection
Authors: Thakur E. R. , Gurtman M. B. , Keefer L. , Brenner D. M. , Lackner J. M. ,   Representing the IBS Outcome Study Research Group
Published: August 2015

Background

While irritable bowel syndrome (IBS) affects women more than men, the reasons are unclear. Research on the female preponderance of IBS has focused on gender differences in sex‐linked biological processes; much less attention has been paid to the role of psychosocial factors. Interpersonal difficulties may be one source of stress that may significantly impact on women with IBS. Because of the importance that women attach to relationships, we suspected they would be more reactive to interpersonal stress.

Methods

A total of 283 (M age = 41 years, F = 80%), Rome III‐diagnosed IBS patients completed a test battery that included the IBS Symptom Severity Scale, McGill Pain Questionnaire, Inventory of Interpersonal Problems (IIP), interpersonal support evaluation list (social support), Negative Interactions Scale, Brief Symptom Inventory (distress), Beck Depression Inventory, Anxiety Sensitivity Inventory, and IBS‐Quality of Life as part of baseline assessment of an NIH trial.

Key Results

Males scored higher on two IIP scales reflecting a hostile‐dominant interpersonal pattern, and reported less social support. The quality of relationship problems (more interpersonal difficulties, lower support) correlated with IBS symptom severity as measured mainly by gastroenterologists.

Conclusions & Inferences

Male, not female, IBS patients reported more interpersonal difficulties. Male patients—a population for whom little is known—are characterized by hostile‐dominant interpersonal problems. This finding has clinical importance, given that relationship problems may influence MDs' estimation of IBS symptom severity and undermine the physician–patient relationship.
Simulated heat waves affected alpine grassland only in combination with drought
Authors: De Boeck Hans J. , Bassin Seraina , Verlinden Maya , Zeiter Michaela , Hiltbrunner Erika
Published: August 2015

The Alpine region is warming fast, and concurrently, the frequency and intensity of climate extremes are increasing. It is currently unclear whether alpine ecosystems are sensitive or resistant to such extremes.

We subjected Swiss alpine grassland communities to heat waves with varying intensity by transplanting monoliths to four different elevations (2440–660 m above sea level) for 17 d. Half of these were regularly irrigated while the other half were deprived of irrigation to additionally induce a drought at each site.

Heat waves had no significant impacts on fluorescence (Fv/Fm, a stress indicator), senescence and aboveground productivity if irrigation was provided. However, when heat waves coincided with drought, the plants showed clear signs of stress, resulting in vegetation browning and reduced phytomass production. This likely resulted from direct drought effects, but also, as measurements of stomatal conductance and canopy temperatures suggest, from increased high‐temperature stress as water scarcity decreased heat mitigation through transpiration.

The immediate responses to heat waves (with or without droughts) recorded in these alpine grasslands were similar to those observed in the more extensively studied grasslands from temperate climates. Responses following climate extremes may differ in alpine environments, however, because the short growing season likely constrains recovery.
Stress‐triggered redox signalling: what's in pROSpect?
Authors: Foyer Christine H , Noctor Graham
Published: August 2015

Reactive oxygen species (ROS) have a profound influence on almost every aspect of plant biology. Here, we emphasize the fundamental, intimate relationships between light‐driven reductant formation, ROS, and oxidative stress, together with compartment‐specific differences in redox buffering and the perspectives for their analysis. Calculations of approximate H2O2 concentrations in the peroxisomes are provided, and based on the likely values in other locations such as chloroplasts, we conclude that much of the H2O2 detected in conventional in vitro assays is likely to be extracellular. Within the context of scant information on ROS perception mechanisms, we consider current knowledge, including possible parallels with emerging information on oxygen sensing. Although ROS can sometimes be signals for cell death, we consider that an equally important role is to transmit information from metabolism to allow appropriate cellular responses to developmental and environmental changes. Our discussion speculates on novel sensing mechanisms by which this could happen and how ROS could be counted by the cell, possibly as a means of monitoring metabolic flux. Throughout, we place emphasis on the positive effects of ROS, predicting that in the coming decades they will increasingly be defined as hallmarks of viability within a changing and challenging environment.
Photochemistry and Photobiology of the Spore Photoproduct: A 50‐Year Journey
Authors: Setlow Peter , Li Lei
Published: August 2015

Fifty years ago, a new thymine dimer was discovered as the dominant DNA photolesion in UV‐irradiated bacterial spores [Donnellan, J. E. & Setlow R. B. (1965) Science, 149, 308–310], which was later named the spore photoproduct (SP). Formation of SP is due to the unique environment in the spore core that features low hydration levels favoring an A‐DNA conformation, high levels of calcium dipicolinate that acts as a photosensitizer, and DNA saturation with small, acid‐soluble proteins that alters DNA structure and reduces side reactions. In vitro studies reveal that any of these factors alone can promote SP formation; however, SP formation is usually accompanied by the production of other DNA photolesions. Therefore, the nearly exclusive SP formation in spores is due to the combined effects of these three factors. Spore photoproduct photoreaction is proved to occur via a unique H‐atom transfer mechanism between the two involved thymine residues. Successful incorporation of SP into an oligonucleotide has been achieved via organic synthesis, which enables structural studies that reveal minor conformational changes in the SP‐containing DNA. Here, we review the progress on SP photochemistry and photobiology in the past 50 years, which indicates a very rich SP photobiology that may exist beyond endospores.
The Political Consequences of Party System Change
Authors: Nwokora Zim , Pelizzo Riccardo
Published: August 2015

This article engages one of the important gaps in the literature on party system effects: the consequences of party system change. We discuss how existing empirical approaches to party system change do not actually capture the changeability of patterns of party competition, which is the most direct understanding of the term “party system.” We propose a measure that does exactly this: the index of fluidity. Applying this measure to countries in South East Asia, we show that party system change is associated with harmful effects, including lower foreign direct investment and deterioration of the rule of law.

Related Articles

Beal, Amanda L., and
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Luckhurst, Jonathan, and
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Related Media

Cochrane, Joe. 2014. New York Times. September 4. http://www.nytimes.com/2014/09/05/world/asia/in‐southeast‐asia‐indonesia‐becomes‐a‐role‐model‐for‐democracy.html?_r=0

Yueh, Linda. 2014. “Rule of Law v. Rule of Party.” BBC Online. October 24. http://www.bbc.com/news/business‐29754688

Pilling, David. 2014. Financial Times. June 8. http://www.ft.com/intl/cms/s/0/da2c5ee0‐779e‐11e3‐807e‐00144feabdc0.html#axzz3ZXbY2NXV
Acclimation of fine root respiration to soil warming involves starch deposition in very fine and fine roots: a case study in Fagus sylvatica saplings
Authors: Di Iorio Antonino , Giacomuzzi Valentino , Chiatante Donato
Published: August 2015

Root activities in terms of respiration and non‐structural carbohydrates (NSC) storage and mobilization have been suggested as major physiological roles in fine root lifespan. As more frequent heat waves and drought periods within the next decades are expected, to what extent does thermal acclimation in fine roots represent a mechanism to cope with such upcoming climatic conditions? In this study, the possible changes in very fine (diameter < 0.5 mm) and fine (0.5–1 mm) root morphology and physiology in terms of respiration rate and NSC [soluble sugars (SS) and starch] concentrations, were investigated on 2‐year‐old Fagus sylvatica saplings subjected to a simulated long‐lasting heat wave event and to co‐occurring soil drying. For both very fine and fine roots, soil temperature (ST) resulted inversely correlated with specific root length, respiration rates and SSs concentration, but directly correlated with root mass, root tissue density and starch concentration. In particular, starch concentration increased under 28°C for successively decreasing under 21°C ST. These findings showed that thermal acclimation in very fine and fine roots due to 24 days exposure to high ST (∼28°C), induced starch accumulation. Such ‘carbon‐savings strategy’ should bear the maintenance costs associated to the recovery process in case of restored favorable environmental conditions, such as those occurring at the end of a heat wave event. Drought condition seems to affect the fine root vitality much more under moderate than high temperature condition, making the temporary exposure to high ST less threatening to root vitality than expected.
Methodological recommendations for a heartbeat detection‐based measure of interoceptive sensitivity
Authors: Kleckner Ian R. , Wormwood Jolie Baumann , Simmons W. Kyle , Barrett Lisa Feldman , Quigley Karen S.
Published: August 2015

Heartbeat detection tasks are often used to measure cardiac interoceptive sensitivity—the ability to detect sensations from one's heart. However, there is little work to guide decisions on the optimum number of trials to use, which should balance reliability and power against task duration and participant burden. Here, 174 participants completed 100 trials of a widely used heartbeat detection task where participants attempt to detect whether presented tones occurred synchronously or asynchronously with their heartbeats. First, we quantified measurement reliability of the participant's accuracy derived from differing numbers of trials of the task using a correlation metric; we found that at least 40–60 trials were required to yield sufficient reliability. Next, we quantified power by simulating how the number of trials influenced the ability to detect a correlation between cardiac interoceptive sensitivity and other variables that differ across participants, including a variable measured from our sample (body mass index) as well as simulated variables of varying effect sizes. Using these simulations, we quantified the trade‐offs between sample size, effect size, and number of trials in the heartbeat detection task such that a researcher can easily determine any one of these variables at given values of the other two variables. We conclude that using fewer than 40 trials is typically insufficient due to poor reliability and low power in estimating an effect size, although the optimal number of trials can differ by study.
Cinacalcet and Clinical Outcomes in Dialysis
Authors: Komaba Hirotaka , Fukagawa Masafumi
Published: August 2015

Secondary hyperparathyroidism (SHPT) is a common complication of end‐stage renal disease and is one of the most prominent causes of a markedly increased risk of death and cardiovascular disease in this patient population. Cinacalcet hydrochloride is a new option for the treatment of SHPT, and the efficacy and effectiveness to lower parathyroid hormone levels and to improve control of mineral metabolism, even in patients with severe disease, has been well established in many clinical trials and observational studies. Currently, the focus has moved to the impact of cinacalcet on hard clinical outcomes, and two randomized controlled trials, ADVANCE and EVOLVE, have been performed to assess the effects of cinacalcet on cardiovascular calcification and the risk of cardiovascular events and mortality, respectively. Although the primary analysis of both trials did not find significant effects of cinacalcet, the benefit of cinacalcet was suggested in the subanalyses in which the potential problems of the trials were taken into account. These positive results are consistent with experimental studies showing favorable effects of cinacalcet on bone metabolism and vascular calcification, providing plausibility to support the beneficial effects of cinacalcet. Definitive evidence is, however, still lacking, and further efforts should be made to establish the optimal role of cinacalcet in the treatment of SHPT.
HLA alleles and haplotypes in Burmese (Myanmarese) and Karen in Thailand
Authors: Kongmaroeng C. , Romphruk A. , Puapairoj C. , Leelayuwat C. , Kulski J. K. , Inoko H. , Dunn D. S. , Romphruk A. V.
Published: August 2015

This is the first report on human leukocyte antigen (HLA) allele and haplotype frequencies at three class I loci and two class II loci in unrelated healthy individuals from two ethnic groups, 170 Burmese and 200 Karen, originally from Burma (Myanmar), but sampled while residing in Thailand. Overall, the HLA allele and haplotype frequencies detected by polymerase chain reaction sequence‐specific primer (PCR‐SSP) at five loci (A, B, C,DRB1andDRQB1) at low resolution showed distinct differences between the Burmese and Karen. In Burmese, fiveHLA‐B*15haplotypes with differentHLA‐A andHLA‐DR/DQcombinations were detected with three of these not previously reported in other Asian populations. The data are important in the fields of anthropology, transplantation and disease‐association studies.
The middle and upper Lochkovian (Lower Devonian) conodont successions in key peri‐Gondwana localities (Spanish Central Pyrenees and Prague Synform) and their relevance for global correlations
Authors: Valenzuela‐Ríos José Ignacio , Slavík Ladislav , Liao Jau‐Chyn , Calvo Helena , Hušková Aneta , Chadimová Leona
Published: August 2015

Detailed correlation, based on conodont sequences, between middle and upper Lochkovian carbonate successions from two key peri‐Gondwanan regions, the Spanish Central Pyrenees and the Prague Synform, is attained for the first time. This correlation facilitates the definition of tie points for further multidisciplinary studies that seek to establish high‐resolution temporal subdivision and global correlation. Some intervals have a precision of less than 0.5 Ma, which is significantly greater than in previous studies. The estimated elapsed time considered herein is about 3.2 Ma and is subdivided into five major zones of global scope: transitans‐trigonicus, trigonicus‐kutscheri, kutscheri‐pandora β, pandora β‐gilberti and gilberti‐steinachensis β. By providing tie points and globally applicable criteria, this research contributes to the international cooperative effort to subdivide the Devonian standard stages into globally recognised substages.
Drug‐induced immune hemolytic anemia associated with anti‐carboplatin and the first example of anti‐paclitaxel
Authors: Leger Regina M. , Jain Shweta , Nester Theresa A. , Kaplan Henry
Published: August 2015

BACKGROUND

Combined chemotherapy with carboplatin and paclitaxel is first‐line treatment for lung and ovarian cancer. Drug‐induced antibodies to carboplatin are rare but can cause severe, even fatal, hemolysis. Paclitaxel‐induced immune hemolysis has not been reported. We describe a case of immune‐mediated hemolysis associated with antibodies to carboplatin and paclitaxel in a woman with ovarian cancer who had received multiple chemotherapeutic agents over 7 years, including several courses of these two drugs. She required many transfusions. During a chemotherapy infusion the patient became hypotensive, was pale, and had rigors and red urine. The nadir hematocrit was 12.4%; peak bilirubin and lactate dehydrogenase were 16.3 mg/dL and 1188 units/L, respectively.

STUDY DESIGN AND METHODS

Blood samples collected within hours after chemotherapy and 2 days later were tested for antibodies to carboplatin and paclitaxel.

RESULTS

The direct antiglobulin test was positive with anti‐IgG (3+) and anti‐C3 (2+). The plasma collected shortly after chemotherapy agglutinated carboplatin‐treated red blood cells (RBCs); untreated and paclitaxel‐treated RBCs both reacted at the antiglobulin test most likely due to circulating carboplatin, paclitaxel, or both drugs. Serum collected 2 days later agglutinated (titer 2) and sensitized (titer 128) carboplatin‐treated RBCs; untreated and paclitaxel‐treated RBCs were nonreactive. An acid eluate reacted weakly in the presence of polyethylene glycol with carboplatin‐treated RBCs. The serum reacted with untreated and enzyme‐treated RBCs in the presence of soluble carboplatin and paclitaxel.

CONCLUSION

Anti‐carboplatin and the first example of anti‐paclitaxel were detected in this patient's sample.
Fear of blood draw and total draw time combine to predict vasovagal reactions among whole blood donors
Authors: France Christopher R. , France Janis L. , Frame‐Brown Terri A. , Venable Geri A. , Menitove Jay E.
Published: August 2015

BACKGROUND

Fear of blood draws is a predictor of vasovagal reaction risk among whole blood donors, and this relationship is particularly evident among less experienced donors. This study examines the combined effect of donor fear and total blood draw time on vasovagal reactions.

STUDY DESIGN AND METHODS

After successfully completing the blood donor health screening, 2730 whole blood donors attending high school drives were asked about their fear of having blood drawn. Donor reports of fear versus no fear were combined with total blood draw time to predict phlebotomist ratings of donor vasovagal reactions.

RESULTS

Both fear and draw time were significant predictors of vasovagal reactions, with observed reaction rates of 31.2% for fearful donors whose blood draw lasted 10 minutes or more versus 5.0% for nonfearful donors whose draw lasted less than 6 minutes. Binomial regression analyses revealed that fear remained a significant predictor of reaction rates across all blood draw intervals examined (odds ratio, 2.8‐4.1; all p < 0.001) and that these effects were maintained after controlling for donor sex, weight, estimated blood volume, pulse rate, and donation status.

CONCLUSION

This report shows that both fear and blood draw time increase vasovagal reaction rates, and the two are additive. These findings suggest that fearful donors should be the focus of special attention to reduce their distress before donation as well as careful observation throughout the draw.
IS QUANTUM INDETERMINISM REAL? THEOLOGICAL IMPLICATIONS
Authors: Vanney Claudia E.
Published: August 2015

Quantum mechanics (QM) studies physical phenomena on a microscopic scale. These phenomena are far beyond the reach of our observation, and the connection between QM's mathematical formalism and the experimental results is very indirect. Furthermore, quantum indeterminism defies common sense. Microphysical experiments have shown that, according to the empirical context, electrons and quanta of light behave as waves and other times as particles, even though it is impossible to design an experiment that manifests both behaviors at the same time. Unlike Newtonian physics, the properties of quantum systems (position, velocity, energy, time, etc.) are not all well‐defined simultaneously. Moreover, quantum systems are not characterized by their properties, but by a wave function. Although one of the principles of the theory is the uncertainty principle, the trajectory of the wave function is controlled by the deterministic Schrödinger equations. But what is the wave function? Like other theories of the physical sciences, quantum theory assigns states to systems. The wave function is a particular mathematical representation of the quantum state of a physical system, which contains information about the possible states of the system and the respective probabilities of each state.
THE SIGNIFICANCE OF EVITABILITY IN NATURE
Authors: Keogh Gary
Published: August 2015

Assessing the current situation of the religion–science dialogue, it seems that a consensus of nonconsensus has been reached. This nonconsensus provides a pluralistic context for the religion and science dialogue, and one area where this plurality is clear is the discourse on relational models of God and creation. A number of interesting models have gained attention in contemporary theological dialogue with science, yet there is an overriding theme: an emphasis on God's involvement with the world. In this article, I argue that theology has been preoccupied with this emphasis. It is suggested that the theme of the freedom of nature has been underrepresented. This theme of the freedom of nature I argue carries important theological implications. It is suggested that acts or events gain their significance largely by way of being contextualized by the fact that such acts or events could have been otherwise, a realization that might provide the various relational models of God and the world food for thought.
LANGUAGE AS A VALUES‐REALIZING ACTIVITY: CARING, ACTING, AND PERCEIVING
Authors: Hodges Bert H.
Published: August 2015

A problem for natural scientific accounts, psychology in particular, is the existence of value. An ecological account of values is reviewed and illustrated in three domains of research: carrying differing loads; negotiating social dilemmas involving agreement and disagreement; and timing the exposure of various visual presentations. Then it is applied in greater depth to the nature of language. As described and illustrated, values are ontological relationships that are neither subjective nor objective, but which constrain and obligate all significant animate activity physically, socially, and morally. As an embodied social activity, conversational dialogue is characterized in terms of values, pragmatics, and presence rather than in terms of syntactic and semantic rules. In particular the nature of dialogical arrays is explored, and the hypothesis that language is an action system, a perceptual system, and a caring system is explored. Language expands horizons and makes it possible for humans to realize their calling as culture makers and caretakers.
The Effect of Selected Grease Components on the Wear Behavior of Grease-Lubricated Gears
Authors: Schultheiss Hansjörg , Tobie Thomas , Stahl Karsten
Published: August 2015

For gears that are operated at slow speeds, wear is often the failure mode that limits gear lifetime. Gears running at slow speeds are often lubricated with grease. The composition of the grease has a significant effect not only on gear lifetime but also on lubrication costs. Therefore, the selection of a suitable grease for a given gear application requires a good knowledge of its expected performance in regard to wear. In order to better understand the wear behavior of gears lubricated with grease, an understanding of the influence that different grease components, e.g., base oil type and viscosity, thickener type, additive type, and solid lubricants, have on gear wear behavior is important. In this paper, systematic investigations on the influence of different grease components on the wear behavior of slow running, case carburized gears were conducted using the FZG back-to-back gear test rig. The emphasis of the experimental work presented herein lies on the effect that the base oil viscosity and type, additive type, type of soap thickener, as well as the type and concentration of solid lubricants have on the gear wear behavior at low pitch line velocities. The investigations showed that the base oil type and viscosity only have a slight effect on gear wear behavior under boundary lubrication conditions. However, the thickener type and especially the additive type as well as the solid lubricant type significantly affect the wear behavior of gears running at slow speeds and lubricated with grease.
Control of Separations in a Highly-Loaded Axial Compressor Cascade by Tailored Boundary Layer Suction
Authors: Mao Xiaochen , Liu Bo , Zhang Guochen
Published: August 2015

In order to study the effectiveness and mechanisms of boundary layer suction (BLS) in controlling both the boundary layer separation on the whole span of suction surface (SS) and the three-dimensional (3D) separation in the corner, a 3D linear compressor cascade was investigated by tailored BLS. First, experimental investigations at a range of incidences from −10° to 10° were undertaken on both the original cascade and the aspirated cascade (SS1) in a high-subsonic cascade wind tunnel. The results show that the profile loss coefficient of the aspirated cascade is reduced remarkably as the suction flow ratio increases at the incidences from −5° to 8°. Based on the experimental investigations, numerical simulations were employed to study the flow fields of the original and aspirated cascade in detail. It was found that part blade span suction on the aspirated cascade can effectively remove the separation at the suction span where suction slot exists, resulting that the flow fields of other spans deteriorated.

Due to the interaction of separations both on the SS and the end-wall, the 3D separation in the corner are more complicated, so another three tailored BLS schemes were designed totally in order to fully remove both the boundary-layer separation on SS and the 3D separation. It was found that the span-wise distribution of static pressure was changed after suction and it could influence the transport of the low-energy fluid between the end-wall and the mid-span. The separation over the whole span of SS and the 3D separation in the corner were fully eliminated by combined suction scheme (CS). Finally, the incidence characteristics of the 3D linear cascade under the control of CS scheme were investigated numerically together with the suction flow rate matching problem of the different suction slots.
An Annular Pulsed Detonation Combustor Mockup: System Identification and Misfiring Detection
Authors: Wolff Sascha , King Rudibert
Published: August 2015

An annular pulsed detonation combustor basically consists of a number of detonation tubes which are firing in a predetermined sequence into a common downstream annular plenum. Fluctuating initial conditions and fluctuating environmental parameters strongly affect the detonation. Operating such a set-up without misfiring is delicate. Misfiring of individual combustion tubes will significantly lower performance or even stop the engine. Hence, an operation of such an engine requires a misfiring detection.

Here, a model-based approach is used which exploits the innovation sequence calculated by a Kalman filter. The model necessary for the Kalman filter is determined based on a modal identification technique. A surrogate, nonreacting experimental set-up is considered in order to develop and test these methods.
Use of Fin Equation to Calculate Nusselt Numbers for Rotating Discs
Authors: Tang Hui , Shardlow Tony , Owen J. Michael
Published: August 2015

Conduction in thin discs can be modelled using the fin equation, and there are analytical solutions of this equation for a circular disc with a constant heat-transfer coefficient. However, convection (particularly free convection) in rotating-disc systems is a conjugate problem: the heat transfer in the fluid and the solid are coupled, and the relative effects of conduction and convection are related to the Biot number, Bi, which in turn is related to the Nusselt number. In principle, if the radial distribution of the disc temperature is known then Bi can be determined numerically. But the determination of heat flux from temperature measurements is an example of an inverse problem where small uncertainties in the temperatures can create large uncertainties in the computed heat flux. In this paper, Bayesian statistics are applied to the inverse solution of the circular fin equation to produce reliable estimates of Bi for rotating discs, and numerical experiments using simulated noisy temperature measurements are used to demonstrate the effectiveness of the Bayesian method. Using published experimental temperature measurements, the method is also applied to the conjugate problem of buoyancy-induced flow in the cavity between corotating compressor discs.
Forced Response of a Centrifugal Compressor Stage due to the Impeller-Diffuser Interaction
Authors: Walton Edward J. , Tan Choon S.
Published: August 2015

The impact mode coupling between impeller blades and the disk backwall has on the forced response amplitude of impeller blades is assessed. The assessments focus on the forced response of two splitter blade modes to a variety of representative boundary conditions and unsteady loadings. The forcing function is the synchronous unsteady loading generated by the impeller-diffuser interaction at resonance. The results indicate that modal coupling of blade and disk dominant modes renders the forced response highly sensitive to small variations in airfoil and disk backwall thickness. As a complement, a reduced-order model based on the forced response of a two mass-spring system is used to elucidate the physical interaction of modal coupling. The practical implication of this finding is that a forced response issue with an impeller blade cannot be addressed adequately by stiffening the structure, such as thickening the blade or disk. Thus appropriate measures need to be taken to avoid potential blade-disk mode couplings within the manufacturing tolerances of the part.
Aerodynamic and Aeroacoustic Analyses of a Regenerative Blower
Authors: Heo Man-Woong , Seo Tae-Wan , Lee Chung-Suk , Kim Kwang-Yong
Published: August 2015

This paper presents a parametric study to investigate the aerodynamic and aeroacoustic characteristics of a side channel regenerative blower. Flow analysis in the side channel blower was carried out by solving three-dimensional steady and unsteady Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence closure. Aeroacoustic analysis was conducted by solving the variational formulation of Lighthill’s analogy on the basis of the aerodynamic sources extracted from the unsteady flow analysis. The height and width of the blade and the angle between inlet and outlet ports were selected as three geometric parameters, and their effects on the aerodynamic and aeroacoustic performances of the blower have been investigated. The results showed that the aerodynamic and aeroacoustic performances were enhanced by decreasing height and width of blade. It was found that angle between inlet and outlet ports significantly influences the aerodynamic and aeroacoustic performances of the blower due to the stripper leakage flow.
Rational Technique for Multistage Centrifugal Pump CFD-Modeling
Authors: Zubanov Vasiliy M. , Shabliy Leonid S. , Krivcov Alexander V.
Published: August 2015

This article reports CFD-modeling technique of flow through a kerosene pump and suggests appropriate CFD tools, model configuration, types of boundary conditions, turbulence models and meshing technique. The flow features were analyzed and error of the CFD-model was estimated. The CFD results were compared with experimental results. The final CFD-model, which was also verified with the impeller radial load estimation, shows that the technique produces sufficient accurate results with less computational cost. The technique can be used for the design optimization of a multistage pump.
Unsteady Pressure Investigations of Corner Separated Flow in a Linear Compressor Cascade
Authors: Zambonini Gherardo , Ottavy Xavier
Published: August 2015

The aim of this work is to present detailed unsteady pressure measurements of three-dimensional flow field in a NACA 65 linear compressor cascade. Chord-based Reynolds number of 382000 and incidence angle of 4 degrees were chosen as target configuration of the rig, which clearly presents the corner separation phenomenon at the juncture of the blade suction side and the end-wall. Concerning the experiments, a characterization of the mean and fluctuating component of wall static pressure on the surface of a specially developed blade is achieved at first. This fluctuating component is investigated utilizing nineteen high sensitivity condenser microphones plugged into blade cavities which have been carefully calibrated. Transfer functions obtained by calibration are exploited to reconstruct the time-dependent pressure signal and finally statistics, conditional ensemble averages, coherence and spectra analyses of fluctuations are presented in order to investigate the unsteady characteristics of the corner separation. High values of root mean square are individuated near the leading edge and in the separation region on the suction surface of the blade. Skewness and kurtosis show an intermittent behavior of the separation onset, which moves upstream and downstream on the suction surface. This intermittency of the separation line is probably linked with the existence of a bimodal behavior of the size of the corner separation. The analyses of coherence and conditional ensemble average between the signals at the leading edge and at the onset of the separation suggest a critical influence of angle and velocity of the incoming end-wall boundary layer on the positive pressure signatures of the shear layer, which characterize the inception of the separation.
Development of a Predictive Method for Quantifying Vortex-Shedding Pulsation Amplitudes in Compressor Piping Systems
Authors: Simons Sarah , Broerman Eugene L. , Brun Klaus
Published: August 2015

One of the design criteria for centrifugal compressor piping systems is the prevention of piping and valve failures from high pulsation amplitudes and vibration caused by vortex-shedding induced (VSI) pulsations of gas flow past closed piping branches (stubs). Most vortex-shedding analyses are performed on the basis of frequency avoidance. If a coincidence is predicted between the acoustic natural frequency of a piping segment and the flow induced vortex shedding frequency, piping changes must be made to avoid the coincidence, since there is currently no known method for accurately predicting the severity of the resulting pulsation amplitudes and, therefore, the possibility of piping failures. Often, these piping changes are expensive and time consuming and likely unnecessary for smaller bore piping (10-inch or less), assuming the flow-acoustic coincidence does not coincide with a mechanical resonance.

The majority of research performed to date on vortex-shedding excitation of piping stubs focuses on predicting the frequencies of excitation using an experimentally determined Strouhal number or range of numbers for a given geometry or piping feature. However, to properly design a piping system using a combination of support structures and piping changes, reliable prediction of the pulsation amplitude is essential for determining the shaking forces acting on the piping system and the resulting vibration and stress amplitudes. Due to the expense of experimental testing and availability of equipment, it is difficult to obtain accurate amplitude measurements of VSI pulsations of fluids at Reynolds numbers typically associated with natural gas transmission.

This paper describes a series of experimental tests performed to record vortex-shedding induced pulsation amplitudes in three test facilities. Three different process fluids were utilized varying the operating conditions to obtain gas flows with Reynold’s numbers between 1e5 and 2e7. Steady state flow, temperature and pressure data was recorded with ASME PTC-10 compliant instrumentation. Transient pressure data was taken with dynamic pressure transducers installed at each stub end as well as in the main piping near the tee. The geometry configurations, pulsation amplitudes, and calculated Strouhal numbers associated with each test configuration are presented. Comparison was made between the test results and several previously published formulas. From the test results, a predictive method was developed to best represent the limit of the pulsation amplitudes.
Effects of Blade Deformation on the Performance of a High Flow Coefficient Mixed Flow Impeller
Authors: Hazby Hamid , Woods Ian , Casey Michael , Numakura Ryusuke , Tamaki Hideaki
Published: August 2015

The effects of blade deformation under running conditions on the performance of a highly loaded transonic mixed flow impeller were investigated. Two impellers were manufactured, one using the “running” blade profiles as designed and one using the converted “unrunning” or “cold” geometry. Both impellers were tested experimentally and investigated numerically.

The test data taken with smooth casing showed that at maximum speed, the isentropic efficiency and pressure ratio of the running geometry was higher than the unrunning geometry by about 0.4% and 1.4%, respectively. However, the difference in performance diminished in the presence of recirculating casing treatment. Numerical calculations suggested that the differences at high speeds were mainly due to the variation in the impeller tip clearance. The calculations using deformed blade profiles under centrifugal load only, predicted performance differences which were about twice as high as the measured values. However, closer predictions were obtained when the effects of pressure loads on blade deformation were included using closely coupled fluid-structural analyses.
Loss Mechanisms and Flow Control for Improved Efficiency of a Centrifugal Compressor at High Inlet Prewhirl
Authors: Xinqian Zheng , Qiangqiang Huang , Anxiong Liu
Published: August 2015

Variable inlet prewhirl is an effective way to suppress compressor instability. Compressors usually employ a high degree of positive inlet prewhirl to shift the surge line in the performance map to a lower mass flow region. However, the efficiency of a compressor at high inlet prewhirl is far lower than that at zero or low prewhirl. This paper investigates the performances of a centrifugal compressor with different prewhirl, discusses the mechanisms thought to be responsible for the production of extra loss induced by high inlet prewhirl and develops flow control methods to improve efficiency at high inlet prewhirl. The approach combines steady three-dimensional Reynolds average Navier-Stockes (RANS) simulations with theoretical analysis and modeling. In order to make the study universal to various applications with inlet prewhirl, the inlet prewhirl was modeled by modifying the velocity condition at the inlet boundary. Simulation results show that the peak efficiency at high inlet prewhirl is reduced compared to that at zero prewhirl by over 7.6 percentage points. The extra loss is produced upstream and downstream of the impeller. Severe flow separation was found near the inlet hub which reduces efficiency by 2.3 percentage points. High inlet prewhirl works like a centrifuge gathering low-kinetic-energy fluid to hub, inducing the separation. A dimensionless parameter C is defined to measure the centrifugal component of flow. As for the extra loss produced downstream of the impeller, the flow mismatch of impeller and diffuser at high prewhirl causes a violent backflow near the diffuser vanes’ leading edges. An analytical model is built to predict diffuser choking mass flow which proves that the diffuser flow operates outside of stable conditions. Based on the two loss mechanisms, hub curve and diffuser stager angle were modified and adjusted for seeking higher efficiency at high prewhirl. The efficiency improvement of a modification of the hub is 1.1 percentage points and that of the combined optimization is 2.4 percentage points. During optimizing, constant distribution of inlet prewhirl was found to induce reverse flow at the leading edge of the blade root, which turned out being uncorrelated with blade angle. By revealing loss mechanisms and proposing flow control ideas, this paper lays a theoretical basis for overcoming the efficiency drop induced by high inlet prewhirl and for developing compressors with high inlet prewhirl.
Turbine Blade Surface Phantom Cooling From Upstream Nozzle Trailing Edge Ejection
Authors: Li Shiou-Jiuan , Yang Shang-Feng , Han Je-Chin , Zhang Luzeng , Moon Hee-Koo
Published: August 2015

This paper presents upstream nozzle trailing edge coolant ejection on downstream uncooled blades. Pressure sensitive paint (PSP) mass transfer technique provides detailed phantom cooling effectiveness distribution on a modeled land-based turbine rotor blade surfaces. Cavity purge and tip leakage flows are excluded, and a uniform blade inlet temperature is adopted in the current study. Experiments have completed in a low speed wind tunnel facility with a five blade linear cascade. The inlet Reynolds numbers based on chord length are 100,000 and 200,000. Nozzle trailing edge coolant ejection on rotor blade is simulated by a spoked wheel-type rotating facility with 32 hollow rods equipped with coolant ejection from 128 holes per rod. Coolant to mainstream density ratio maintains at 1.5 to match engine conditions. Nozzle coolant discharge velocity to nozzle mainstream velocity ratio varies from 0.4 to 1.4. Velocity ratios from 0.4 to 0.6 are closest to typical engine conditions. Coolant to mainstream mass flow rate ratio (MFR) is from 0.67% to 2.94%. Higher phantom cooling effectiveness occurs on suction and pressure surfaces at the velocity ratio from 0.4 to 0.6 and over 1.0, respectively. Velocity ratio effect impacts on phantom cooling effectiveness distribution more than MFR effect. Most of trailing edge coolant migrates toward blade inner and outer spans than blade mid-span. Further investigation of the trailing edge coolant ejection including cavity purge and tip leakage flows is essential for understanding real applications.
A Combined Analytical and Numerical Approach to Analyze Mud Motor Excited Vibrations in Drilling Systems
Authors: Hohl Andreas , Hohl Carsten , Herbig Christian
Published: August 2015

Severe vibrations in drillstrings and bottomhole assemblies can be caused by cutting forces at the bit or mass imbalances in downhole tools. One of the largest imbalances is related to the working principle of the so-called mud motor, which is an assembly of a rotor that is maintained by the stator. One of the design-related problems is how to minimize vibrations excited by the mud motor.

Simulation tools using specialized finite element methods (FEM) are established to model the mechanical behavior of the structure. Although finite element models are useful for estimating rotor dynamic behavior and dynamic stresses of entire drilling systems they do not give direct insight how parameters affect amplitudes and stresses. Analytical models show the direct influence of parameters and give qualitative solutions of design related decisions. However these models do not provide quantitative numbers for complicated geometries.

An analytical beam model of the mud motor is derived to calculate the vibrational amplitudes and capture basic dynamic effects. The model shows the direct influence of parameters of the mud motor related to the geometry, material properties and fluid properties. The analytical model is compared to the corresponding finite element model. Vibrational amplitudes are discussed for different modes and parameter changes. Finite element models of the entire drilling system are used to verify the findings from the analytical model using practical applications. The results are compared to time domain and statistical data from laboratory and field measurements.