bluuebunny/crossref_metadata_2025 huggingface dataset:
Democracy, Voting, and Disenfranchisement in the United States: A Social Psychological Perspective
Authors: Lanning Kevin
Published: August 2008

Autonomy, engagement, and equality are defining features of democracy. Each of these features illuminates the challenge or incompleteness of our democratic aspirations: Autonomy or self‐governance is too easily surrendered, disengagement is evident when roughly half of eligible adults choose not to vote, and the inequality of our political voices is manifest in many ways, including a self‐perpetuating relationship between socioeconomic status and political participation. In addition to introducing the present collection of articles on the social psychology of voting, I argue that several concepts drawn from psychological measurement may contribute to making elections more fair. A signal detection framework may be used to assess the soundness of election reforms, with fraud and disenfranchisement conceptualized as two forms of error. The replacement of the Electoral College by a single aggregate national popular vote would not only be more democratic but would substantially reduce the likelihood of controversial outcomes in future presidential elections.
A Game‐Theoretic View of Voting
Authors: Krueger Joachim I. , Acevedo Melissa
Published: August 2008

Two game‐theoretic arguments for the potential rationality of voting are presented. The first argument suggests that people make choices that allow the most favorable forecasts. People choose to vote inasmuch as they project their own choices between voting and abstaining more strongly onto members of their own political group than onto members of other political groups. Relevant evidence is reviewed and extended by new findings in a simulated public‐goods dilemma. The second argument suggests that people preview how they will feel about each of the four possible scenarios generated by the conjunctions of their own choices (to vote or to abstain) and the election outcome (victory or defeat). They choose to vote inasmuch as they feel their own vote will not be wasted. The implications of both arguments for efforts to increase turnout are discussed.
The “Antidemocratic Personality” Revisited: A Cross‐National Investigation of Working‐Class Authoritarianism
Authors: Napier Jaime L. , Jost John T.
Published: August 2008

More than 60 years ago, psychologists identified a potential threat to democracy from within, namely the “antidemocratic personality” arising from the “authoritarian syndrome.” It was soon discovered that the problem of authoritarianism was especially acute among those who were low in education and income, and that it was associated with intolerance toward others. However, several important questions were left unresolved. We revisit fundamental theoretical and empirical questions concerning the existence and nature of “working‐class authoritarianism,” focusing especially on four psychological aspects of authoritarianism, namely, conventionalism, moral absolutism, obedience to authority, and cynicism. In a cross‐national investigation involving respondents from 19 democratic countries, we find that all four aspects of authoritarianism are indeed related to moral and ethnic intolerance. However, only obedience to authority and cynicism are especially prevalent among those who are low in socioeconomic status. Conventionalism and moral absolutism were significant predictors of economic conservatism, whereas obedience to authority and cynicism were not. We find no support for

Lipset's (1960)

claim that working‐class authoritarianism would be associated with economic liberalism. Instead, we find that authoritarianism is linked to right‐wing orientation in general and that intolerance mediates this relationship. Implications for electoral politics and political psychology are discussed.
Social Policy, Feminism, and Research on Violence in Close Relationships
Authors: Frieze Irene Hanson
Published: August 2008

The history of research on intimate partner violence is reviewed, with a special focus on how my own work in this area has evolved. The role of researcher values in the research process is highlighted. Some of the issues emerging from this review are the need for better measures of intimate partner violence, reasons why women's violence has been ignored by many researchers, and a discussion of the conditions under which women display violence. Policy implications of this research are discussed.
Determinants of Performance Measurement: An Investigation into the Decision to Conduct Citizen Surveys
Authors: Dalehite Esteban G.
Published: August 2008

This article develops and tests a comprehensive framework explaining the decision to measure performance, specifically the decision of local governments to conduct citizen surveys. It is structured around a fundamental distinction between subjective performance measures obtained for use in decision making and those that are produced solely for their symbolic value. The author suggests that the field of public administration may be taking a simplified view concerning the promotion and adoption of citizen surveys, overlooking important aspects of the decision‐making process of performance‐oriented public managers and neglecting the impact of politics and symbols. Political rationality may undercut managerial rationality in the decision to adopt citizen surveys, and symbolic adoption may be the underlying cause of low levels of information use. This study identifies policies to increase adoption of citizen surveys but cautions that simply promoting the adoption of surveys as inherently good may be a naive and wasteful course of action. Practitioners who have already made the decision to measure subjective performance through citizen surveys, or are facing such a decision, can find in this analysis a structure to assess past decisions or guide future decisions.
Contrast and Foundation of the Public Oversight Roles of the U.S. Government Accountability Office and the U.K. National Audit Office
Authors: Norton Simon D. , Smith L. Murphy
Published: August 2008

This paper examines and compares, according to the New Public Management approach, the U.S. watchdog, the Government Accountability Office, in its ability to oversee and call to account the executive branch of government, and its U.K. counterpart, the National Audit Office. Results of this examination indicate that the Government Accountability Office is more effective than its U.K. counterpart. Its greater effectiveness is attributable to the fact that it derives its powers and legitimacy from a written constitution; in contrast, in the United Kingdom there is no equivalent document defining the relationship between the state and the citizenry. As a consequence, the powers, duties, and self‐perception of the National Audit Office are significantly weaker and more mutable than those of the Government Accountability Office.
Negative regulation of lymphocyte development and function by the Cbl family of proteins
Authors: Huang Fang , Gu Hua
Published: August 2008

Summary: Negative regulation of intracellular signaling delivered by the antigen receptors and coreceptors plays an important role in lymphocyte development and activation. Recent data from our laboratory and others have identified the Cbl family of ubiquitin ligases as important negative regulators in both T‐cell and B‐cell antigen receptor and coreceptor signaling. We show that c‐Cbl and Cbl‐b, two members of the Cbl family of proteins, play a redundant role in establishing the major histocompatibility complex‐dependent development of thymocytes and in thymic selection. They also control the activation threshold and CD28 costimulatory signaling in peripheral T cells. In B cells, c‐Cbl and Cbl‐b set the B‐cell receptor signaling threshold critical for proper B‐cell maturation and anergy induction. Biochemical studies indicate that the immune regulation by Cbl proteins correlate with their ubiquitin ligase function. Inactivation of Cbl‐b also renders mice resistant to both transplanted and spontaneous tumors due to an enhanced anti‐tumor immunity of CD8+ T cells. These findings thus place Cbl proteins at the center of a complex immune network regulation and suggest that modulation of this signaling pathway may be beneficiary to the treatment of autoimmunity and cancer.
Control of peripheral T‐cell tolerance and autoimmunity via the CTLA‐4 and PD‐1 pathways
Authors: Fife Brian T. , Bluestone Jeffrey A.
Published: August 2008

Summary: Classically, the CD28/cytotoxic T‐lymphocyte antigen‐4 (CTLA‐4) and B7 families of cell surface molecules regulate complex signaling pathways that profoundly affect T‐cell responses. The recent identification and characterization of additional CD28 and B7 family members including programmed death‐1 (PD‐1), programmed death ligand‐1 (PD‐L1) (B7‐H1), and PD‐L2 (B7‐DC) has added to the complexity and greater appreciation of how surface molecules control T‐cell activation and peripheral tolerance. CD28/B7 interactions mediate co‐stimulation and significantly enhance peripheral T‐cell responses. CTLA‐4, in contrast, interacting with the same B7 molecules, results in decreased T‐lymphocyte activity and regulates the immune response. Similarly, PD‐1 interactions with PD‐L1 and PD‐L2 downmodulate T‐cell immune responses. Despite these similarities, the regulatory roles of the CTLA‐4 and PD‐1 pathways are distinct. This may be due, at least in part, to the differential expression patterns of the CTLA‐4 and PD‐1 ligands both temporally and spatially. This article examines the role of CTLA‐4 and PD‐1 in limiting autoreactivity and establishing peripheral self‐tolerance with the hypothesis that CTLA‐4 signals are required early in the lymph node during initiation of an immune response and PD‐1 pathways act late at the tissue sites to limit T‐cell activity.
Immunoreceptor tyrosine‐based inhibition motifs: a quest in the past and future
Authors: Daëron Marc , Jaeger Sébastien , Du Pasquier Louis , Vivier Eric
Published: August 2008

Summary: Since an immunoreceptor tyrosine‐based inhibition motif (ITIM) was first identified in the intracytoplasmic domain of FcγRIIB, ITIMs have been found in a large number of inhibitory molecules that were shown to negatively regulate cell activation. Due to their wide tissue distribution and to the variety of their extracellular ligands, ITIM‐containing molecules are involved in the control of a large spectrum of biological functions, mostly but not exclusively related to immunity. On the basis of sequence comparison, ITIMs were structurally defined as 6‐amino acid sequences containing a tyrosine (Y) with loosely conserved N‐terminal (Y−2) and C‐terminal (Y+3) residues. Molecular analysis of signaling events demonstrated that when coaggregated with activating receptors, ITIMs are phosphorylated by Src‐family tyrosine kinases, which enables them to recruit Src homology 2 domain‐containing phosphatases that antagonize activation signals. Because ITIM‐dependent negative regulation seems to be a fundamental regulatory mechanism, both in rodents and in humans, and because it can be used either as a target or as a powerful tool in various diseases, we undertook (i) a genome‐wide search of potential novel ITIM‐containing molecules in humans, mice, frogs, birds, and flies and (ii) a comparative analysis of potential ITIMs in major animal phyla, from mammals to protozoa. We found a surprisingly high number of potential ITIM‐containing molecules, having a great diversity of extracellular domains, and being expressed by a variety of immune and non‐immune cells. ITIMs could be traced back to the most primitive metazoa. The genes that encode ITIM‐containing molecules that belong to the immunoglobulin superfamily or to the C‐lectin family seem to derive from a common set of ancestor genes and to have dramatically expanded and diverged in Gnathostomata (from fish to mammals).
Prioritising potential guilds of specialist herbivores as biological control agents for prickly acacia through simulated herbivory
Authors: Dhileepan K. , Lockett C. , Robinson M. , Pukallus K.
Published: August 2008

Understanding plant response to herbivory facilitates the prioritisation of guilds of specialist herbivores as biological control agents based on their potential impacts. Prickly acacia (Acacia nilotica ssp. indica) is a weed of national significance in Australia and is a target for biological control. Information on the susceptibility of prickly acacia to herbivory is limited, and there is no information available on the plant organ (i.e. leaf, shoot and root in isolation or in combination) most susceptible to herbivory. We evaluated the ability of prickly acacia seedlings, to respond to different types of simulated herbivory (defoliation, shoot damage, root damage and combinations), at varying frequencies (no herbivory, single, two and three events of herbivory) to identify the type and frequency of herbivory that will be required to reduce the growth and vigour. Defoliation and shoot damage, individually, had a significant negative impact on prickly acacia seedlings. For the defoliation to be effective, more than two defoliation events were required, whereas a single bout of shoot damage was enough to cause a significant reduction in plant vigour. A combination of defoliation + shoot damage had the greatest negative impact. The study highlights the need to prioritise specialist leaf and shoot herbivores as potential biological control agents for prickly acacia.
Extracorporeal Photopheresis Normalizes Some Lymphocyte Subsets (Including T Regulatory Cells) in Chronic Graft‐Versus‐Host‐Disease
Authors: Bladon John , Taylor Peter
Published: August 2008

Abstract:  Extracorporeal photopheresis (ECP) has been demonstrated to be clinically effective for the treatment of steroid‐refractory graft‐versus‐host‐disease (GvHD). Recently, a murine model suggested that ECP may modulate the allo‐reactivity, seen in GvHD, by enhancement of T regulatory cells. T regulatory cells are an important component of immune tolerance and reduced levels of them have been observed in chronic GvHD. Samples were taken from eight chronic GvHD patients prior to receiving any ECP therapy and after three months of ECP. Samples were also obtained from eight age‐ and sex‐matched normal controls. Each sample was evaluated for absolute levels of total lymphocytes and CD4+ and CD8+ T cells. T regulatory cell numbers were also assessed accordingly: CD4+CD25high, CD4+CD25highCD69‐, CD4+CD25highCD152+ and CD4+CD25highFOXP3+. Following three months of ECP, increases in the absolute counts of total lymphocytes, CD4+ and CD8+ T cells and T regulatory cells were observed; however, no selective statistical increase in the percentage of T regulatory cell numbers was observed within the CD4+ T cell compartment. ECP induces an increase in T regulatory cell numbers; however, this is not specific as there is also an enhancement of both total lymphocyte and CD4+ T cell numbers. The positive effect of ECP may therefore depend on a more generic re‐adjustment of immune homeostasis.
A Case Report of Nephrotic Syndrome Due to Collapsing Focal Segmental Glomerulosclerosis Treated With Low‐density Lipoprotein Apheresis
Authors: Miyazono Motoaki , Tomiyoshi Yoshiyuki , Kishi Tomoya , Ikeda Yuji , Sakemi Takanobu , Sanai Toru , Node Koichi
Published: August 2008

Abstract:  We herein report the case of a 73‐year‐old woman with steroid and cyclosporine resistant collapsing focal segmental glomerulosclerosis (FSGS) whose refractory proteinuria and hypoproteinemia were controlled with low‐density lipoprotein apheresis (LDL‐A). She was initially treated with steroid therapy, including methylprednisolone pulse and cyclosporine therapy. However, her hypoproteinemia, accompanied with renal insufficiency, persisted despite these therapies. We treated her using LDL‐A and found improvement in her urine protein excretion, hyperlipidemia, hypoproteinemia, and renal function as a result of this treatment. This suggests that LDL‐A may therefore be an effective therapy for nephrotic syndrome due to collapsing FSGS.
Recognition, diagnosis, and treatment of restless legs syndrome
Authors: Smith Jennifer E. , Tolson Jerry M.
Published: August 2008

Purpose: To review the symptoms, diagnosis, and treatment of restless legs syndrome (RLS) and its relevance to nurse practitioners (NPs).

Data sources: Comprehensive review of the scientific literature on the diagnosis and treatment of RLS in adults.

Conclusions: RLS is a chronic neurological disorder that, with varying degrees of severity, affects 5%–10% of the general population. Because of the circadian pattern of onset, the symptoms of RLS may be associated with significant sleep disturbance and may have a negative impact on quality of life. RLS is characterized by a compelling urge to move the legs and usually accompanied or caused by uncomfortable sensations in the legs. Symptoms begin or worsen during periods of rest or inactivity and are worse in the evening or at night. Other features supportive of a diagnosis include a family history, the presence of periodic leg movements in sleep, and the relief of symptoms after treatment with a dopaminergic therapy. Although the etiology of RLS is unknown, it is thought that symptoms result from a central dopaminergic dysfunction and dopamine agonists are considered first‐line treatment for moderate‐to‐severe primary RLS. Nondopaminergic therapies and nonpharmacologic interventions may also be appropriate in the management of less severe cases of RLS.

Implications for practice: NPs are often the first healthcare providers to see patients with RLS and therefore need to be able to accurately recognize and diagnose the disorder; this, in turn, will enable them to successfully manage the treatment of RLS.
Bilirubin cholelithiasis and haemosiderosis in an anaemic pyruvate kinase‐deficient Somali cat
Authors: Van Geffen C. , Savary‐Bataille K. , Chiers K. , Giger U. , Daminet S.
Published: August 2008

A Somali cat was presented with recurrent anorexia, lethargy, vomiting and icterus. A macrocytic‐hypochromic, regenerative haemolytic anaemia was identified and hereditary pyruvate kinase deficiency was confirmed by means of breed‐specific DNA mutation analysis. The case was complicated by the presence of markedly elevated serum liver enzyme activities, hyperbilirubinaemia, coagulopathy and ultrasonographic evidence of gall bladder choleliths and extrahepatic bile duct obstruction. The choleliths consisted of 100 per cent bilirubin, likely because of chronic haemolysis and haeme degradation. In conclusion, haemosiderosis and bilirubin cholelithiasis can be a consequence of chronic haemolysis in pyruvate kinase‐deficient cats, as seen in human beings with a variety of chronic haemolytic disorders.
Autoimmune myasthenia gravis and dysautonomia in a dog
Authors: Gajanayake I. , Niessen S. J. M. , Cherubini G. B. , Diane Shelton G.
Published: August 2008

A two‐year‐old male entire border collie dog was evaluated for a short history of mixed bowel diarrhoea, coughing, vomiting and stranguria. Physical examination revealed dyspnoea with increased ventral lung sounds and a flaccidly distended bladder. Neurological examination revealed poor pupillary light reflexes, an absent gag reflex and a poor anal tone. Thoracic radiography was consistent with megaoesophagus and aspiration pneumonia. Clinicopathological testing revealed an elevated muscular nicotinic acetylcholine receptor antibody titre. The dog was euthanased because of clinical deterioration. Cerebrospinal fluid (CSF) collected immediately post‐mortem revealed macrophagic pleocytosis. Post‐mortem histopathological examination was consistent with dysautonomia. This is the first report of coexisting autoimmune myasthenia gravis and dysautonomia in a non‐human species. The concomitant diseases may suggest a common immunopathological aetiology.
Canine dynamic left ventricular outflow tract obstruction: assessment of myocardial function and clinical outcome
Authors: Loureiro J. , Smith S. , Fonfara S. , Swift S. , James R. , Dukes‐McEwan J.
Published: August 2008

Objective:The aims of this study were (i) to evaluate echocardiographic findings and myocardial function including pulsed wave tissue Doppler imaging in dogs with naturally occurring dynamic left ventricular outflow tract obstruction and (ii) to investigate the clinical outcome and response to therapy in these dogs.

Methods:Two cases were retrospectively reviewed and three cases were prospectively evaluated including clinical findings, diagnostic test results (including standard Doppler echocardiography and pulsed wave tissue Doppler imaging), response to treatment and outcome. The two retrospective cases received no treatment. Other cases were treated with a β‐blocker.

Results:All dogs had a variable intensity left apical systolic murmur. Concentric left ventricular hypertrophy, systolic anterior motion of the mitral valve and scimitar‐shaped left ventricular outflow tract Doppler flow profile were present in all cases. Pulsed wave tissue Doppler imaging interrogation of the interventricular septum revealed E′/A′ reversal in all but one patient. Regression of left ventricular hypertrophy and total resolution of the dynamic left ventricular outflow tract obstruction were observed in all cases.

ClinicalSignificance:Young dogs are affected with a possible terrier breed predisposition. Dynamic left ventricular outflow tract obstruction may be distinguished from canine hypertrophic cardiomyopathy as progressive resolution of echocardiographic abnormalities was documented. Pulsed wave tissue Doppler imaging abnormalities provide further evidence for significant diastolic dysfunction associated with the hypertrophy.
The Effects of Blade Passing on the Heat Transfer Coefficient of the Overtip Casing in a Transonic Turbine Stage
Authors: Thorpe Steven J. , Ainsworth Roger W.
Published: August 2008

In a modern gas turbine engine, the outer casing (shroud) of the shroudless high-pressure turbine is exposed to a combination of high flow temperatures and heat transfer coefficients. The casing is consequently subjected to high levels of convective heat transfer, a situation that is complicated by flow unsteadiness caused by periodic blade-passing events. In order to arrive at an overtip casing design that has an acceptable service life, it is essential for manufacturers to have appropriate predictive methods and cooling system configurations. It is known that both the flow temperature and boundary layer conductance on the casing wall vary during the blade-passing cycle. The current article reports the measurement of spatially and temporally resolved heat transfer coefficient (h) on the overtip casing wall of a fully scaled transonic turbine stage experiment. The results indicate that h is a maximum when a blade tip is immediately above the point in question, while the lower values of h are observed when the point is exposed to the rotor passage flow. Time-resolved measurements of static pressure are used to reveal the unsteady aerodynamic situation adjacent to the overtip casing wall. The data obtained from this fully scaled transonic turbine stage experiment are compared to previously published heat transfer data obtained in low-Mach number cascade-style tests of similar high-pressure blade geometries.
The Influence of Shroud and Cavity Geometry on Turbine Performance: An Experimental and Computational Study—Part I: Shroud Geometry
Authors: Rosic Budimir , Denton John D. , Curtis Eric M.
Published: August 2008

Imperfections in the turbine annulus geometry, caused by the presence of the shroud and associated cavity, have a significant influence on the aerodynamics of the main passage flow path. In this paper, the datum shroud geometry, representative of steam turbine industrial practice, was systematically varied and numerically tested. The study was carried out using a three-dimensional multiblock solver, which modeled the flow in a 1.5 stage turbine. The following geometry parameters were varied: inlet and exit cavity length, shroud overhang upstream of the rotor leading edge and downstream of the trailing edge, shroud thickness for fixed casing geometry and shroud cavity depth, and shroud cavity depth for the fixed shroud thickness. The aim of this study was to investigate the influence of the above geometric modifications on mainstream aerodynamics and to obtain a map of the possible turbine efficiency changes caused by different shroud geometries. The paper then focuses on the influence of different leakage flow fractions on the mainstream aerodynamics. This work highlighted the main mechanisms through which leakage flow affects the mainstream flow and how the two interact for different geometrical variations and leakage flow mass fractions.
The Influence of Shroud and Cavity Geometry on Turbine Performance: An Experimental and Computational Study— Part II: Exit Cavity Geometry
Authors: Rosic Budimir , Denton John D. , Curtis Eric M. , Peterson Ashley T.
Published: August 2008

The geometry of the exit shroud cavity where the rotor shroud leakage flow reenters the main passage flow is very important due to the dominant influence of the leakage flow on the aerodynamics of low aspect ratio turbines. The work presented in this paper investigates, both experimentally and numerically, possibilities for the control of shroud leakage flow by modifications to the exit shroud cavity. The processes through which the leakage flow affects the mainstream aerodynamics identified in the first part of this study were used to develop promising strategies for reducing the influence of shroud leakage flow. The experimental program of this study was conducted on a three-stage model air turbine, which was extensively supported by CFD analysis. Three different concepts for shroud leakage flow control in the exit cavity were analyzed and tested: (a) profiled exit cavity downstream end wall, (b) axial deflector, and (c) radial deflector concepts. Reductions in aerodynamic losses associated with shroud leakage were achieved by controlling the position and direction at which the leakage jet reenters the mainstream when it leaves the exit shroud cavity. Suggestions are made for an optimum shroud and cavity geometry.
The Augmentation of Internal Blade Tip-Cap Cooling by Arrays of Shaped Pins
Authors: Bunker Ronald S.
Published: August 2008

The objective of the present study is to demonstrate a method to provide substantially increased convective heat flux on the internal cooled tip cap of a turbine blade. The new tip-cap augmentation consists of several variations involving the fabrication or placement of arrays of discrete shaped pins on the internal tip-cap surface. Due to the nature of flow in a 180deg turn, the augmentation mechanism and geometry have been designed to accommodate a mixture of impingementlike flow, channel flow, and strong secondary flows. A large-scale model of a sharp 180deg tip turn is used with the liquid crystal thermography method to obtain detailed heat transfer distributions over the internal tip-cap surface. Inlet channel Reynolds numbers range from 200,000 to 450,000 in this study. The inlet and exit passages have aspect ratios of 2:1, while the tip turn divider-to-cap distance maintains nearly the same hydraulic diameter as the passages. Five tip-cap surfaces were tested including a smooth surface, two different heights of aluminum pin arrays, one more closely spaced pin array, and one pin array made of insulating material. Effective heat transfer coefficients based on the original smooth surface area were increased by up to a factor of 2.5. Most of this increase is due to the added surface area of the pin array. However, factoring this surface area effect out shows that the heat transfer coefficient has also been increased by about 20–30%, primarily over the base region of the tip cap itself. This augmentation method resulted in negligible increase in tip turn pressure drop over that of a smooth surface.
Measurements in Film Cooling Flows With Periodic Wakes
Authors: Womack Kristofer M. , Volino Ralph J. , Schultz Michael P.
Published: August 2008

Film cooling flows subject to periodic wakes were studied experimentally. The wakes were generated with a spoked wheel upstream of a flat plate. Cases with a single row of cylindrical film cooling holes inclined at 35deg to the surface were considered at blowing ratios of 0.25, 0.50, and 1.0 with a steady freestream and with wake Strouhal numbers of 0.15, 0.30, and 0.60. Temperature measurements were made using an infrared camera, thermocouples, and constant current (cold-wire) anemometry. Hot-wire anemometry was used for velocity measurements. The local film cooling effectiveness and heat transfer coefficient were determined from the measured temperatures. Phase locked flow temperature fields were determined from cold-wire surveys. Wakes decreased the film cooling effectiveness for blowing ratios of 0.25 and 0.50 when compared to steady freestream cases. In contrast, effectiveness increased with Strouhal number for the 1.0 blowing ratio cases, as the wakes helped mitigate the effects of jet lift-off. Heat transfer coefficients increased with wake passing frequency, with nearly the same percentage increase in cases with and without film cooling. The time resolved flow measurements show the interaction of the wakes with the film cooling jets. Near-wall flow measurements are used to infer the instantaneous film cooling effectiveness as it changes during the wake passing cycle.
Combined Effects of Wakes and Jet Pulsing on Film Cooling
Authors: Womack Kristofer M. , Volino Ralph J. , Schultz Michael P.
Published: August 2008

Pulsed film cooling jets subject to periodic wakes were studied experimentally. The wakes were generated with a spoked wheel upstream of a flat plate. Cases with a single row of cylindrical film cooling holes inclined at 35deg to the surface were considered at blowing ratios B of 0.50 and 1.0 with jet pulsing and wake Strouhal numbers of 0.15, 0.30, and 0.60. Wake timing was varied with respect to the pulsing. Temperature measurements were made using an infrared camera, thermocouples, and constant current (cold wire) anemometry. The local film cooling effectiveness and heat transfer coefficient were determined from the measured temperatures. Phase locked flow temperature fields were determined from cold-wire surveys. With B=0.5, wakes and pulsing both lead to a reduction in film cooling effectiveness, and the reduction is larger when wakes and pulsing are combined. With B=1.0, pulsing again causes a reduction in effectiveness, but wakes tend to counteract this effect somewhat by reducing jet lift-off. At low Strouhal numbers, wake timing had a significant effect on the instantaneous film cooling effectiveness, but wakes in general had very little effect on the time averaged effectiveness. At high Strouhal numbers, the wake effect was stronger, but the wake timing was less important. Wakes increased the heat transfer coefficient strongly and similarly in cases with and without film cooling, regardless of wake timing. Heat transfer coefficient ratios, similar to the time averaged film cooling effectiveness, did not depend strongly on wake timing for the cases considered.
Optimizing Learning Convergence Speed and Converged Error for Precision Motion Control
Authors: Bristow Douglas A. , Alleyne Andrew G. , Tharayil Marina
Published: August 2008

This brief paper considers iterative learning control (ILC) for precision motion control (PMC) applications. This work develops a methodology to design a low pass filter, called the Q-filter, that is used to limit the bandwidth of the ILC to prevent the propagation of high frequencies in the learning. A time-varying bandwidth Q-filter is considered because PMC reference trajectories can exhibit rapid changes in acceleration that may require high bandwidth for short periods of time. Time-frequency analysis of the initial error signal is used to generate a shape function for the bandwidth profile. Key parameters of the bandwidth profile are numerically optimized to obtain the best tradeoff in converged error and convergence speed. Simulation and experimental results for a permanent-magnet linear motor are included. Results show that the optimal time-varying Q-filter bandwidth provides faster convergence to lower error than the optimal time-invariant bandwidth.
Iterative Learning Velocity and Tension Control for Single Span Axially Moving Materials
Authors: Zhao Haiyu , Rahn Christopher D.
Published: August 2008

Precise tension and speed control of axially moving material systems enables high speed processing of paper, plastics, fibers, and films. A single span model is developed that includes distributed longitudinal vibration, a torque-controlled roller at the left boundary, and a speed-controlled roller at the right boundary. The speed trajectory of the right roller is assumed periodic but unknown. A proportional and derivative (PD) feedback and iterative learning control (ILC) feedforward control law is developed for the left roller torque based on the measured tension and speed at the left boundary. PD tension/speed control is proven to ensure boundedness of distributed displacement and tension. ILC is proven to provide the same theoretical result but greatly improved simulated response to an aggressive stop/start right roller speed trajectory.
Fixed Structure Feedforward Controller Design Exploiting Iterative Trials: Application to a Wafer Stage and a Desktop Printer
Authors: van der Meulen Stan H. , Tousain Rob L. , Bosgra Okko H.
Published: August 2008

In this paper, the feedforward controller design problem for high-precision electromechanical servo systems that execute finite time tasks is addressed. The presented procedure combines the selection of the fixed structure of the feedforward controller and the optimization of the controller parameters by iterative trials. A linear parametrization of the feedforward controller in a two-degree-of-freedom control architecture is chosen, which results in a feedforward controller that is applicable to a class of motion profiles as well as in a convex optimization problem, with the objective function being a quadratic function of the tracking error. Optimization by iterative trials avoids the need for detailed knowledge of the plant, achieves the controller parameter values that are optimal with respect to the actual plant, and allows for the adaptation to possible variations that occur in the plant dynamics. Experimental results on a high-precision wafer stage and a desktop printer illustrate the procedure.
Two-Phase Flow Induced Vibration of an Array of Tubes Preferentially Flexible in the Flow Direction
Authors: Violette R. , Mureithi N. W. , Pettigrew M. J.
Published: August 2008

Tests were done to study the fluidelastic instability of a cluster of seven cylinders much more flexible in the flow direction than in the lift direction. The array configuration is rotated triangular with a pitch to diameter ratio of 1.5. The array was subjected to two-phase (air-water) cross flow. Cylinder natural frequencies of 14 and 28 Hz were tested. Fluidelastic instabilities were observed at 65, 80, 90 and 95% void fraction albeit at a somewhat higher flow velocity than that expected for axisymetrically flexible arrays. These results and additional wind tunnel results are compared to existing data on fluidelastic instability.
Large Diameter Spiral Wound Gasket Behavior, Measured on the Entire Gasket and on Small Gasket Sectors
Authors: Delaunay Yannick , Fontaine Yannick
Published: August 2008

Gasket manufacturers usually verify the properties of large diameter spiral wound gaskets with a compression test on a very small sector, supposed to behave identically to the global structure. However, full size tests performed at the sealing laboratory of EDF R&D showed high discrepancy between the behavior of a full gasket, and the behavior of a single sector measured by manufacturers. We found out that the preliminary blank tests, consisting in measuring the test rig deformations under compression, are not carried out with the most accurate procedure by the manufacturers, and might yield wrong results. Indeed, the test rig deformations should be measured during a compression test with a rigid metallic ring instead of the gasket, with the same dimensions. Without metallic ring, the test rig deformations can be much underestimated, and consequently the gasket deformations overestimated.
Creep Failure of a Chromized Waterwall Tube in a Supercritical Boiler
Authors: French Stephen , Skelonis Carl
Published: August 2008

In Spring, 2000, as part of a continuous mitigation program for circumferential cracking and waterwall wastage, 88 tubes, in panel sections of 22 tubes, were installed into the centerwall of a supercritical boiler. The replacement tubes were low alloy (1-1/4Cr-1/2Mo) steel chromized to a nominal depth of 12–20 mils (0.3–0.5 mm). After only three years of operation, one tube failed due to creep. Four months later, a second creep failure occurred in the same centerwall panel and four other tubes were removed due to visual variations in dimension. Two months later, two more tubes were removed with bulges. Two months following that, during the scheduled overhaul, seven other tubes were removed due to the formation of bulges and extensive creep damage was found in three of the four panels comprising the chromized tube section. Metallurgical evidence indicates tube metal temperatures in excess of 1000°F. Creep testing was performed on samples taken from this unit and its identical sister unit. The first data shows the creep properties to fall near the minimum band for this Cr-Mo alloy, but the testing remains ongoing.
Discussion of Miner’s Rule on Type 304 Austenitic Stainless Steel at 288 C in Air
Authors: Hayashi Makoto
Published: August 2008

The surface worked type 304 stainless steel exhibits an extraordinary behavior when subjected random fatigue load. In this study the effect of load history on the cumulative damage was examined. The random loads are 1) two step increasing stresses, 2) two step decreasing stresses, 3) repeated high and low step stresses, 4) repeated low and high step stresses, and 5) gradually increasing stresses. In any cases the cumulative damage calculated according to Miner’s rule remarkably exceeded 1.0, especialy for the gradually increasing stresses. In order to survey the mechanism, the elastic and plastic strain behaviors were studied. The extraordinal cumulative fatigue damage could be explained by the remarkable fatigue hardening behavir of austenitic stainless steel.
A Single Technically Consistent Design Formula for the Thickness of Cylindrical Sections Under Internal Pressure
Authors: Fishburn John D.
Published: August 2008

Within the current design codes for boilers, piping and pressure vessels, there are many different equations for the thickness of a cylindrical section under internal pressure. A reassessment of these various formulations, using the original data, is described together with more recent developments in the state of the art. A single formula, which can be demonstrated to retain the same design margin in both the time-dependent and time-independent regimes, is shown to give the best correlation with the experimental data and is proposed for consideration for inclusion in the design codes.
Performance Demonstration Based Probability of Detection (POD) Curves for Fatigue Cracks in Piping
Authors: Gosselin S. R. , Simonen F. A. , Heasler P. G. , Becker F. L. , Doctor S. R. , Carter R. G.
Published: August 2008

This paper evaluates non-destructive examination (NDE) detection capabilities for fatigue cracks in piping. Industry performance demonstration initiative (PDI) data for fatigue crack detection were used to develop a matrix of statistically based probability of detection (POD) curves that consider various NDE performance factors. Seven primary performance factors were identified — Material, Crack Geometry/Type, NDE Examination Access, NDE Procedure, Examiner Qualification, Pipe Diameter, and Pipe Wall Thickness. A database of 16,181 NDE performance observations, with 18 fields associated with each observation, was created and used to develop statistically based POD curves for 42 stainless steel and 14 carbon steel performance cases. Subsequent comparisons of the POD fits for each of the cases showed that excellent NDE performance for fatigue cracks can be expected for ferritic materials. Very little difference was observed between the POD curves for the 14 carbon steel performance cases considered in this study and NDE performance could therefore be represented by a single POD curve. For stainless steel, very good performance can also be expected for circumferential cracks located on the same side of the weld from which the NDE examination is made. POD depended primarily on component thickness. Three POD curves for stainless steel were prepared. Best estimate and the associated 95% confidence bounds for POD versus through-wall depth logistic regression digital data are provided. Probabilistic fracture mechanics (PFM) calculations were performed to compare best estimate leak probabilities obtained from both the new performance-based POD curves and previous PFM models. This work was performed under joint funding by EPRI and the U.S. Department of Energy (DOE), Office of Nuclear Energy Science and Technology’s Nuclear Energy Plant Optimization (NEPO) program.
Codes and Standards for Gaseous Hydrogen Vessels
Authors: Rana Mahendra D. , Rawls George B. , Sirosh Neel
Published: August 2008

In an attempt to support the ongoing effort on hydrogen fuel infrastructure in USA, a need has been identified for ASME Code rules for 15,000 psi gaseous hydrogen vessels for stationary storage as well as transport applications. This paper presents a review of existing rules which are being used in the design and manufacture of high pressure hydrogen vessels. The applicable rules given in the ASME Section VIII Code and the rules given in the DOT, ISO and NGV standards have been reviewed. Limitations on the materials, design, and manufacturing for 15,000 psi vessels are discussed.
Performance of a Drum Type Packaging With Urethane Foam Overpack Subjected to Crush and Other Regulatory Tests
Authors: Smith Allen C. , Gelder Lawrence F. , Blanton Paul S. , Lutz Rex N.
Published: August 2008

General Purpose Fissile Package (GPFP) prototypes of two configurations, 16 in. and 18 1/2 in. diameter drum overpacks, were subjected to the free-drop, crush, puncture, and thermal Hypothetical Accident Condition (HAC) sequential tests for 10CFR71, Type B packagings. The tests demonstrated that the prototypes are very robust, easily withstanding the structural tests. The tests also confirmed that the urethane foam-filled overpack was able to withstand the thermal test.
Metallurgical Failure Analysis of a Rotating Blade in the Compressor Section of a Gas Turbine
Authors: Ellis Fred V.
Published: August 2008

A metallurgical failure analysis was performed for the stage 17 gas turbine rotating blade and stationary vane. Four pieces including the failed rotating and stationary blades were removed from the air compressor section of a gas turbine. The damaged components were found during a borescope examination. The objectives were to determine the failure mechanism and to estimate an inspection interval. The measured chemical compositions of the rotating blade and stationary vane are consistent with that of 403 stainless steel. The failure mechanism for the rotating blade is fatigue based on the beachmarks on the fracture surface and the transgranular cracking. The fatigue crack initiated at the trailing edge of the blade. The crack at the trailing edge is due to impact damage. The probable root cause of failure for the rotating blade is the loss of axial clearance between the stationary and rotating blades. Fatigue crack growth calculations were performed using the NASGRO computer program and the corner cracked plate geometry to estimate the inspection interval. The estimated inspection interval is of order of magnitude hours to days for failure by high cycle fatigue crack growth.
The Stress Analysis for the Trenchless Pipeline Rehabilitation
Authors: Lee Kuang-Chyi , Jou Rong-Yuan , Yu Hsin Her , Liang Yuan-Cheng , Lin Chien-Chang
Published: August 2008

Most of the pipelines will get aging year after year and then they will need to be rehabilitated. Because of the heavy traffic on the ground or the congested pipelines under the ground, the replacement of old pipes will be very difficult in the cities. The dig-free (trenchless) method is a revolutionary pipelining method which uses air pressure, hydraulic pressure or mechanical drag force to pull the flexible piping plastic sheet into the old pipe. This research proposes a stress analysis for trenchless pipeline method by the finite element model with CATIA. The material of piping sheet is combined of two different types of epoxy with the anionic harder. We do the stress analysis of the trenchless rehabilitated pipelines to decide the optimal thickness of flexible piping plastic sheet and whether the material is available or not by finite element method.
Influence of Mean Stress on the Fatigue Behavior of 304L SS in Air and PWR Water
Authors: Solomon H. D. , Amzallag C. , Vallee A. J. , De Lair R. E.
Published: August 2008

Load-controlled experiments on 304L stainless steel were run in Air and PWR water, at 150°C and 300°C, with and without a mean stress of 100MPa. These experiments were run to determine the influence of temperature, environment, and mean stress on the 107 Cycle Fatigue Limit stress amplitude. A 100MPa mean stress was found to have different effects at the different temperatures and environments. In contrast to all the conventional models used to describe the effects of mean stress, when the testing was done at 300°C (for both air and PWR water), a 100MPa mean stress was found to raise the 107 Cycle Fatigue Limit relative to that observed without a mean stress. This was ascribed to the effect of the hardening due to the initial straining and to secondary hardening, both of which are more pronounced at 300°C than at 150°C. The increased initial and secondary hardening resulted in the development of less non-elastic strain, thereby improving the fatigue behavior. In PWR water at 150°C, a 100MPa mean stress reduced the 107 Cycle Fatigue Limit by more than that predicted by conventional mean stress models, but in air at 150°C, the decrease in the endurance limit was more in keeping with the predictions of these models. This difference was ascribed to the effect of the PWR water, in the absence of significant initial straining and secondary hardening.
Case Study of Buckling Failure of a Large Liquid Storage Tank
Authors: Mahajerin Enayat , Burgess Gary
Published: August 2008

Large cylindrical tanks are often used to store liquids like milk and chemicals for distribution. These structures are considered thin shells because of their geometry, dimensions, and aspect ratios. In this paper, an actual failure of a large vertical tank is investigated. The tank contained milk and buckled as a result of an internal vacuum caused by human error. Inspection done after failure revealed that an internal vacuum could have been created by a large drop in the inside air temperature. Such tanks are usually washed using extremely hot water. If the water temperature exceeded the manufacturer’s recommendations and the tank is not vented during the cool-down cycle, the contracting air would have drawn a vacuum. Another possibility is that the tank may have been drained without venting the headspace above the milk. This would cause the fixed mass of air above the milk to expand and draw a vacuum. To investigate these scenarios we consider stability of a vertical cylindrical shell under external pressure. The critical pressure differential for buckling of a vertical cylindrical shell with closed ends subjected to uniform axial and radial pressure is known from basic theories of buckling. These equations are used to determine the critical pressure for lobar buckling. The results show that each of these scenarios could have caused failure of the tank. Recommendations to prevent future failures in such storage tanks and design considerations for tanks having arbitrary dimensions and aspect ratios are presented in the paper.