bluuebunny/crossref_metadata_2025 huggingface dataset:
Monoamine concentrations changes in the PTU-induced hypothyroid rat brain and the ameliorating role of folic acid
Authors: Tousson E , Ibrahim W , Arafa N , Akela MA
Published: April 2011

Thyroid hormones are recognized as the key metabolic hormones that play a critical role in the development of central nervous system (CNS) throughout life. The present study was designed to determine the changes in brain monoamine concentrations in 6-n-propyl thiouracil (PTU)-induced hypothyroid rats, in addition to the ameliorating role of folic acid treatment. Fifty male albino rats were equally divided into five groups; first and second groups were the control and folic acid groups, respectively, while the third group was the hypothyroid group in which the rats received PTU in drinking water for 6 weeks. The fourth and fifth groups were co- and post-treated folic acid groups with hypothyroid rats, respectively. Our results revealed that serotonin and norepinephrine concentrations were significantly decreased in the hypothalamus and cortex, while it significantly increased in the hippocampus of hypothyroid rats when compared with control group. Serotonin and norepinephrine concentrations were decreased in hypothalamus and cortex in co- and post-treated folic acid groups with hypothyroid rats, while the concentration of dopamine were significantly increased in the hypothalamus and hippocampus of the hypothyroid rats and co-treated folic acid group with hypothyroid rats. In cortex, the dopamine concentration was significantly increased in hypothyroid rats and post-treated folic acid group with hypothyroid rats, while it significantly decreased in co-treated folic acid group with hypothyroid rats when compared with the control group. Also, our results revealed that, folic acid treatment was better if it is administered as an adjuvant after returning to the euthyroid state by withdrawing PTU from the drinking water.
Acute lupus myocarditis: Clinical features and outcome
Authors: Appenzeller S , Pineau CA , Clarke AE
Published: April 2011

Background: Cardiomyopathy in systemic lupus erythematosus (SLE) may be secondary to myocardial inflammation (i.e. myocarditis) or to systemic complications such as hypertension. Symptomatic left ventricular dysfunction is the most common clinical presentation of cardiomyopathy and is potentially life threatening. Identifying the cause is critical as it dictates therapy.

Methods: We present three cases of left ventricular failure suggestive of myocarditis in SLE patients followed in the Lupus Clinic of the Montreal General Hospital over a 5-year period.

Results: The most frequent presentation is acute onset of a marked reduction of the left ventricular ejection fraction (LVEF). All patients were treated with cardiac support, prednisone, and additional immunosuppressive medications. Improvement of symptoms and LVEF was observed in two of three patients.

Conclusion: Myocarditis is a rare, but life-threatening, manifestation of SLE. With immunosuppressive medications and cardiovascular support, the long-term outcome is usually favorable.
Sinus node dysfunction as an initial presentation of adult systemic lupus erythematosus
Authors: Lin YN , Liou Y-M , Chen J-Y , Chang K-C
Published: April 2011

Cardiac involvement in systemic lupus erythematosus (SLE) has been well described. However, sinus node involvement with profound sinus bradycardia as an early manifestation of adult SLE has not been reported. A 27-year-old previously healthy female was admitted due to intermittent fever for 4 days. SLE was diagnosed based on clinical manifestations and laboratory data. Profound sinus bradycardia (heart rate = 41/min) with weakness was noted during hospitalization. ECG abnormalities completely resolved after a high-dose intravenous steroid infusion. Sinus node involvement with significant bradycardia is one of the possible complications in the early stage of adult SLE. Close cardiovascular monitoring and serial ECGs are suggested for early detection of this serious complication of adult SLE.
Podocyte main slit diaphragm proteins, nephrin and podocin, are affected at early stages of lupus nephritis and correlate with disease histology
Authors: Perysinaki GS , Moysiadis DK , Bertsias G , Giannopoulou I , Kyriacou K , Nakopoulou L , Boumpas DT , Daphnis E
Published: April 2011

Renal podocytes and their slit diaphragms ensure the integrity of the renal basement membrane that forms the barrier to urinary protein loss. A putative disruption of the slit diaphragm and its main protein components, nephrin and podocin, may be implicated in the pathogenesis of lupus nephritis (LN). We studied the glomerular protein expression of nephrin and podocin in NZB/W LN mice by Western blot and immunofluorescence; mRNA levels were measured by real-time PCR. Human kidney biopsies of class II ( n = 5), IV ( n = 4), V ( n = 7) LN were evaluated for nephrin expression by immunohistochemistry. Glomerular protein expression of nephrin and podocin were significantly reduced in NZB/W LN, starting from the earlier stages (mild mesangial LN) and becoming pronounced at advanced histological forms (focal and diffuse proliferative LN). Nephrin and podocin mRNA levels were substantially decreased in diffuse proliferative disease. Decreased expression of both proteins correlated with electron microscopy findings of distorted slit diaphragms. In patients with LN, nephrin was decreased particularly in diffuse proliferative LN. The main slit diaphragm proteins, nephrin and podocin, are affected from the earlier stages of LN and their expression correlates with disease histology. Our findings suggest a novel role of podocytes and their structures in immune-mediated nephritis.
An Experimental Investigation of Unimodal and Bimodal Magnetorheological Fluids with an Application in Prosthetic Devices
Authors: Gudmundsson K.H. , Jonsdottir F. , Thorsteinsson F. , Gutfleisch O.
Published: April 2011

The study investigates the field-induced shear yield stress and the off-state viscosity of selected unimodal and bimodal magnetorheological (MR) fluids. Five grades of commercially available iron powder are used to prepare unimodal MR fluids, one for each powder grade, and bimodal MR fluids, using two grades of micron-sized powder. The iron powder contains particles with a mean diameter ranging from 1 to 8 µm. The solid loading of all fluids is held to a constant value while varying the particle size and the ratio between the coarse and the fine powders. All fluids employ a perfluorinated polyether base fluid whose qualities are described. The bimodal MR fluids are compared to their corresponding unimodal fluids. Results show the bimodal fluids to have a lower off-state viscosity than their corresponding unimodal fluids. An application in prosthetic devices is introduced in which the yielding and the off-state characteristics of the MR fluid are of equal importance. In this application, the shear yield stress determines the rigidness while the off-state viscosity determines the flexibility in the absence of a magnetic field. For this particular application, prominent MR fluids are selected based on the ratio between the on-state yield stress and the off-state viscosity.
Repulsive Normal Force by an Excited Magneto-Rheological Fluid Bounded by Parallel Plates in Stationary or Rotating Shear Mode
Authors: Chan Y.T. , Wong Patrick , Liu K.P. , Bullough W.
Published: April 2011

This article reports results from an experimental study undertaken to determine the magnitude of the repulsive force exerted by a magnetorheological fluid on two bounding parallel and concentric plates under different magnetic field strengths. The plates are stationary without circumferential external loading or in a forced rotational rate for a constant inter plate gap separation. The results show that with stationary plates, the repulsive force increases with the magnitude of the excitation. Upon the addition of a steady-relative rotational speed, the force increases further. The increase in the shear-enhanced repulsive force rose up to a peak and then decreased as the test running, i.e., further increase in the shear strain. The force eventually settled at a steady value which was higher than that due to magnetic field only (no rotation). The main characteristics of the repulsive force against the strain curve are well described by a mathematical model which is derived on the basis of the particle chain tilt phenomenon. The critical twist angles of the plate in the current experimental set up under different magnetic flux densities, which give the maximum repulsive forces, were found to approach a constant value as predicted by the tilt particle chain model.
Through-wall Power Transmission Using an Alternating Magnetic Field and a Multiferroic Energy Harvester
Authors: Zhang C.L. , Yang J.S. , Chen W.Q.
Published: April 2011

We propose to use a magnetic field energy harvester to collect the energy in an alternating magnetic field penetrating an elastic wall. The multiferroic energy harvester consists of a piezomagnetic layer for collecting magnetic energy and a piezoelectric layer for conversion to electric energy. A theoretical analysis is performed using the linear equations for piezomagnetic, piezoelectric, and elastic materials. The output voltage, power, and efficiency are calculated. The effects of various physical and geometric parameters are examined. It is found that the electric output is sensitive to these parameters, and design optimization is needed. Significant output can be achieved near a few resonant frequencies of the structure.
The Effects of Self-Management Education for School-Age Children on Asthma Morbidity
Authors: Ahmad Emily , Grimes Deanna E.
Published: April 2011

The effects of asthma self-management education for school-age children on number of school days missed, emergency department visits and hospital admissions were evaluated through a systematic review of the published research. A total of 9 studies on asthma education programs that were conducted in schools by school nurses and health educators and targeted children 5–18 years of age were reviewed. The studies were all published between 1998 and 2009. The school-based asthma education programs delivered interventions in multiple sessions over short consecutive time periods of about a month to a month and a half. Follow-up data were collected in varying intervals from 1 month to 1 year postinterventions. Results indicated that a decrease in school days missed can be expected from such programs. The data regarding emergency department visits and hospital admissions was less definitive.
A Grey Relation Approach to the Integrated Process of QFD and QE
Authors: Chen Ming-Shi , Lin Chen-Cheng , Tai Yuan-Yeuan , Lin Ming-Chyuan
Published: April 2011

During the process of concurrent design, a designer must focus on meeting the changing requirements of customers and reacting to the rapid decrease of the life-cycle of the product in a dynamic market. However, the cost induced by the quality delinquent and aftermarket service is a critical factor in the enterprise profit. This research proposes a product design methodology that integrates the grey relation approach to quality function deployment (QFD) and quality engineering (QE) to solve the problem. It is noted that the process increases customer satisfaction and enhances product quality in response to global competition. Based on the results of systematic market research performed on customer requirements ( CRs), the hierarchical clustering technique and grey theory have been applied to identify, categorize, and evaluate CRs to rank their grey relational importance. The critical design characteristics ( DCs) have been identified using QFD, which applies the semantic differential method on the relationship matrix cell to evaluate their relationship with CRs. The selected DCs are then evaluated to determine noise and possible loss of quality using the orthogonal experiment of the Taguchi method. The objective of the optimization process is to integrate QFD and QE into the development process and to optimize the quality of product development. With support from a timer manufacturer, six existing products have been selected to demonstrate the applicability of the approach described above. This robust product design process provides encouraging evidence for a new approach that can improve quality, reduce variation, and increase customer satisfaction and enterprise profit.
Hospitalizations in Nursing Homes: Does Payer Source Matter? Evidence From New York State
Authors: Shubing Cai  , Mukamel Dana B. , Veazie Peter , Katz Paul , Temkin-Greener Helena
Published: April 2011

The objective of this study was to examine the reasons for different hospitalization rates between Medicaid and private-pay nursing home residents—to disentangle within-facility differences from across-facility variations in hospitalizations between these two types of residents. Multiple data sources (2003) for New York State were linked. Hospitalization was the dependent variable. Individual payer status was the main independent variable. Facilities were stratified into four groups by ownership status and bed-hold payment eligibility. We found both within-facility (Medicaid residents were more likely to be hospitalized than private-pay residents within a facility) and across-facility differences (facilities with a higher concentration of Medicaid residents were more likely to hospitalize their residents) controlling for individual and facility characteristics. The magnitude of within-facility differences varied with facility ownership and bed-hold eligibility. To reduce hospitalizations of Medicaid residents and to improve both quality of care and costs, policymakers may need to align Medicaid’s and Medicare’s incentives.
The Growth Stages and Maturation of an Outsider-Within: Developing a Critical Gaze and Earning the Right to Speak
Authors: Hendrix Katherine Grace
Published: April 2011

In this autoethnography, I trace the origins of my development as an “outsider-within”; thereby, creating an argument that childhood family lessons, lived experience, and responses to my presence by members of academic in-groups, all have shaped my existence and behavior as “Other” carefully positioned at the edge of the orchard oftentimes referred to as “the life of the mind.” The early stages of my growth into the role of outsider-within are shared along with three phases of maturation into a critical interpretivist researcher: trailblazing, defiance, and crisscrossing the terrain.
White American Style in Rhyme
Authors: Drummond Darlene K.
Published: April 2011

What follows is an experiment in presenting data in a nontraditional way. Accounts of the intraracial experiences of White college women were adapted to various traditional forms of poetry including the villanelle, rondeau, and roundel. These traditional 16th-century French poetry forms featured pastoral verses or tales of romance that were often sung and accompanied by music. However, in following the lead of 19th- and 20th-century English and American poets, the author uses the poetry styles to address serious issues of racial identification, identity negotiation, and enactment. The author employs the principles of variation, alliteration, and rhyming to underscore the impact of various ethnicities and nationalities in making Whiteness visible within the United States.
On Observing Student Silence
Authors: Amundrud Thomas
Published: April 2011

This article uses conversation analysis (CA) to look at how students in an advanced EGAP (English for general academic purposes) course discussion test create and manage the silence of a group member during the 7-min session. This is combined with a personal narrative inquiry, coinspired by autoethnography, on the author’s participation in the discourse and production of these silences. The CA findings indicate that turn allocations and interactional support in discussion test groups appear to be a significant factor in student silences, whereas the reflexive narrative indicates possible pedagogical limitations and changes to the author’s practice. This study concludes by evaluating the research methods used, discussing the tensions and potentials of incorporating narrative techniques with CA and giving possible directions for further inquiry.
Reflective Release: Two Poems About Doing Qualitative Research With AIDS Home-Based Care Volunteers in South Africa
Authors: Naidu Thirusha
Published: April 2011

These two reflective poems emerged from my research on home-based care volunteers caring for terminally ill AIDS patients in rural Kwa-Zulu Natal, South Africa. I found myself overwhelmed by the emancipation offered by qualitative research, particularly when compared with the strict confines of the positivist paradigm that dominates clinical research and practice. My being “left to my own devices” was at once liberating and daunting. Later, when interviewing home-based care volunteers who care for people living with HIV/AIDS, I felt overwhelmed again, this time in a different way. The caregivers were like me in uncharted territory, their work neglected in government policy and practice. The poems granted me an avenue for reflection that helped me assimilate the diversity of experience and emotion with which I was confronted. Giving all of it space in the form of these poems allowed me to get on with the job of research.
Getting in Trouble: Feminist Postcritical Policy Ethnography in an Urban School
Authors: Childers Sara M.
Published: April 2011

This article addresses how the author uses the notion of “getting in trouble” as a source of methodological energy to hold the researcher accountable to the complexities of conducting ethnographic policy studies. She focuses specifically on how a feminist postcritical methodology might be used to read for the disruptions at work in sociocultural policy research and locate analytic tools for getting through anxieties generated by complicated and competing readings of empirical material. The author (re)presents and analyzes troubling material from her own study regarding how one student’s experience of racialized course enrollment was talked about and justified within the context of a “successful” high school. She offers four incommensurable and therefore complementary analytic reads using anthropological, foucaultian, critical race theory, and feminist postcritical frameworks to bring complicated retellings of school enrollment practices into play in an attempt to foreground the lived experiences of policy negotiations and their effects on students.
“Bringing the Message Forward”: Using Poetic Re-presentation to Solve Research Dilemmas
Authors: Ward Angela
Published: April 2011

Researchers cannot always rely on traditional methods for solving research dilemmas. In a research project that explored the friendships and social relationships of four students with severe disabilities in four secondary schools in New Zealand, the author uses poetic re-presentation to solve several ethical and pragmatic research dilemmas. Within a wider context of arts-based research methods, poetic re-presentation is a method of re-presenting participants’ stories to answer research questions. The method involves crafting transcripts in a caring and relational manner to foreground the students’ stories, create verisimilitude and focus on the essence of the experiences, create coherent storylines, and create evocative text. Background to the development of poetic re-presentation in social science research is provided, and a context and rationale for using this method is explored. The process of creating poetic text from transcripts is described and illustrated, using extracts from one student’s stories to contribute to the growing poetry transcription literature.
Cofielding in Qualitative Interviews: Gender, Knowledge, and Interaction in a Study of (Pro)Feminist Men
Authors: Egeberg Holmgren Linn
Published: April 2011

The article is located within research on cross-gender interviewing and concerns methodological and analytical challenges in a study of (pro)feminist men and seeks to contribute to the literature on interview interaction and the knowledge to be gained from such research experiences. The article discusses the negotiation of interviewer/interviewee interaction, practices of gender and theoretical knowledge along with how this might influence the coconstruction of interview performances. Interviewees reflexively turned narratives into theoretical analysis which turned out to be important aspects of presentation of self and in the doings of gender and feminism. The concept of “cofielding” is introduced to address these interview performances but is suggested to have a wider applicability to studies of researcher/researched relationships characterized by discursive closeness and overlapping positions. Cofielding practices point to how the doings of interviewer/interviewee and power relationships can be performed and negotiated—even played with in the speech act of interview interaction.
The Experience of Engaging With Research-Based Drama: Evaluation and Explication of Synergy and Transformation
Authors: Mitchell Gail J. , Dupuis Sherry , Jonas-Simpson Christine , Whyte Colleen , Carson Jennifer , Gillis Jennifer
Published: April 2011

Researchers describe how audiences experienced a research-based drama called I’m Still Here ; a production about persons and families living with dementia. The research drama was created to help diminish the unnecessary suffering that accompanies the misunderstanding and judgment of persons living with dementia. This article describes the immediate experience of seeing, hearing, and feeling research findings that have been transformed through drama. We explored how participants described the experience of engaging with the drama—what words they used, what was felt, and what lingered after the performance was over. Seven patterns or processes, called patterns of synergy are described: seeing anew; connecting with reverberating truths; placing and relating self; sensing embodied impact, discerning meaningful learning; expanding understanding of perspective; and affirming personal knowing. Each pattern of synergy is considered in light of participant quotes and extant literature. Findings support the promise of the arts in health-related research and education.
Attitudinal Correlates of Girls’ Use of Violence in Teen Dating Relationships
Authors: Kernsmith Poco D. , Tolman Richard M.
Published: April 2011

This article explores the applicability of the Theory of Planned Behavior in understanding female perpetrated adolescent dating violence. The Theory of Planned Behavior is intended to predict behavioral intention by examining the actor’s perceptions of consequences and rewards associated with the behavior, social acceptability of the behavior, and behavioral control. Previous research on adult populations has found that the planned behavior model is correlated with violent behavior among males (Tolman, Edleson, & Fendrich, 1996), but not females (Kernsmith, 2005). The current study found that the model partially explained the violent behavior of girls, but only perceptions of social norms were significant.
Understanding Self-Harm in Victims of Intimate Partner Violence: A Qualitative Analysis of Calls Made by Victims to a Crisis Hotline in China
Authors: Wong Susan P. Y. , Cuiling Wang  , Mei Meng  , Phillips Michael R.
Published: April 2011

Text analysis of the transcripts of 26 calls made to a Chinese crisis hotline by victims of intimate partner violence (IPV) reporting thoughts or acts of self-harm abstracted information on victims’ patterns of self-harm and the relationship of their self-harm to IPV. Specific violent episodes often triggered self-harm. Victims considered self-harm a method for airing painful emotions caused by abuse or as a last resort to escape by dying when they saw no other options and were no longer able to endure the violence. We also elaborate on callers’ discussions of barriers to accessing support, sociocultural pressures to preserve “face” and family, and restrictive gender roles that contribute to their self-harm behaviors.
The Mothering Perceptions of Women Abused by Their Partner
Authors: Peled Einat , Gil Inbal Barak
Published: April 2011

This study examined how abused women perceived their mothering. Findings reveal the women’s continuous struggle to function as good mothers in the face of the violence. Their main struggle—to create a buffer between “the children’s world” and the “violent world”—was directed at preventing the abuse from affecting their functioning as mothers, restraining and “fixing” their partner’s violence, and shielding their children from it. Although the women felt that they have succeeded in this task, they also referred to their children’s exposure to violence. The discussion centers on the split evident in the women’s narratives between their mothering and their experience of violence.
A Certain Uncertain Future: A Hospice CEO’s Perspective
Authors: Comeaux Chris
Published: April 2011

Health care organizations across America face an uncertain future. Hospice organizations are no different. There is uncertainty in future revenue sources, staffing, future patient and family demographics, community resources, and, most of all, uncertainty in government regulation of hospice services. Dwelling on this uncertainty can be unsettling, even for a stable, forward-thinking end-of-life care provider. As chief executive officer (CEO) of Four Seasons in Flat Rock, North Carolina, this author is always thinking about how “the unknowns” will affect the 700 patients per day who are provided with hospice and palliative care services in Western North Carolina. Four Seasons is the top hospice provider in North Carolina, serving more than 63% of the deaths in our home county, as determined by its death service ratio. For information about deaths served by hospices in North Carolina by county, see Table I.
Effects of Goal Setting on Dietary and Physical Activity Changes in the Boy Scout Badge Projects
Authors: Latif Hira , Watson Kathy , Nguyen Nga , Thompson Debbe , Baranowski Janice , Jago Russell , Cullen Karen W. , Baranowski Tom
Published: April 2011

Background: This study evaluates the relationship of goal setting to low-fat vegetable (LV) and fruit/100% juice (FJ) consumption and physical activity (PA) change. Methods: A total of 473 10- to 14-year-old Boy Scouts from Houston took part in a 9-week intervention. A two-group (LV and FJ or PA) intervention design was used with each group serving as the control for the other. Internet-based activities included goal setting at home. Food frequencies measured dietary intake. Results: Goals attained were not related to LV intake or PA. Immediate posttest FJ consumption increased about 0.7 servings as home FJ availability increased, but social desirability of response appeared to confound reports of FJ intake at posttest 6 months assessment. Conclusions: Goals attained were not related to LV intake or PA but was related to FJ intake, but only when home FJ availability was high and the relationship was confounded by social desirability of response. Further research is needed with higher quality measures of dietary intake to clarify these relationships.
The paparazzi industry and new media: The evolving production and consumption of celebrity news and gossip websites
Authors: McNamara Kim
Published: April 2011

As a result of media convergence and new visual technologies, paparazzi agencies have emerged as an important force in the entertainment industry. Given the ability of such agencies to create and distribute exclusive stories, the globalization of paparazzi content has increasing ramifications for new forms of information-based entertainment. This article will explore the production, distribution and consumption of paparazzi content, and outline the structure of the paparazzi industry, processes of paparazzi website composition and the rise of the celebrity blogosphere. It draws out implications for new media theory and practice, and provides a framework for the further understanding the impact of paparazzi agencies, celebrity gossip sites and the range of industries affected by this shift in the paparazzi industry.
From entertainment to citizenship: A comparative study of the political uses of popular culture by first-time voters
Authors: Scott Martin , Street John , Inthorn Sanna
Published: April 2011

This article investigates the extent to which young people use different forms of popular culture to express and make sense of their relationship to politics. We look closely at young people's interpretation of popular culture in order to find out whether, and if so how, it plays a political role, using focus groups and interviews with first-time voters in the UK. We adapt the theoretical framework and method used by David Buckingham in his study of the relationship between news media and youth citizenship. While Buckingham concludes that the nature of news media systematically alienates and excludes substantial sectors of the audience, we find that popular culture offers young people a range of often salient ways of expressing and making sense of their relationship to politics.
Modelling and preliminary design issues of a four-axis parallel machine for heavy parts handling
Authors: Company O , Krut S , Pierrot F
Published: April 2011

This paper presents a new four-degree-of-freedom parallel mechanism dedicated to the handling of heavy parts within a large workspace. These four degrees of freedom are three translations and one rotation about a given axis. Such a mechanism is rare; most common parallel mechanisms have three or six degrees of freedom. Firstly, a description of the mechanism is given. Then models are derived regarding velocity and force transformation as input-output relationships. Finally, internal forces models and a stiffness model are evaluated. All models are embedded in a software module aimed at helping with the preliminary design of machines based on this new architecture.
Dynamics of an automotive transmission consisting of a tripod joint and a ball joint. A symbolic approach
Authors: Mariot J-P , K'nevez J-Y
Published: April 2011

The present paper deals with the zero friction dynamics of an automotive transmission consisting of an inboard ball joint close to the wheel and an outboard tripod joint close to the gearbox, connected by an intermediate shaft. The ball joint is a constant-velocity joint (CVJ) whereas the tripod joint is not. In the idealized case of an intermediate shaft of infinite length, the tripod joint behaves like a CVJ and has the following properties: the input and output torque are equal, the transverse forces generating the output torque are equal and there are no shudder vibrations or inertial shaft effects. For a real transmission with a finite-length shaft, deviations from constant-velocity (CV) properties are due to tripod joint angle variation which causes static and dynamic perturbations; these perturbations are expressed symbolically using first-order approximations in terms of tripod joint angle and ratio of shaft length to tulip radius. For most of the front drive cars equipped, the angle of the tripod joint remains close to 0.1 rad; considering a constant input torque at a 100rad/s input velocity, the perturbations are found to be less than 3 per cent for the driving forces when compared with the CVJ.
A Rayleigh-Ritz approach to transverse vibration of isotropic polygonal plates with variable thickness
Authors: Nallim L G , Luccioni B M , Grossi R O
Published: April 2011

This paper presents a simple, computationally efficient and highly accurate numerical model for the study of free vibration behaviour of polygonal plates with variable thickness. The approach developed is based on the Rayleigh-Ritz method and the use of non-orthogonal right triangular coordinates. The deflection of the plate is approximated by a set of beam characteristic orthogonal polynomials generated using the Gram-Schmidt procedure. The algorithm is quite general and can be used to study plates with any combinations of clamped, simply supported and free edge support conditions and also different taper and geometric parameters. Several examples are solved and some results are compared with existing values in the literature. New results are also presented for tapered polygonal plates with different geometrical shapes and combinations of boundary conditions. For some polygonal plates, their mode shapes of free vibration are shown. The study of this problem is of practical importance for a better understanding of the vibration of polygonal plates which are commonly encountered in modern technology.
Adaptive-passive structural vibration attenuation using distributed absorbers
Authors: Jalili N , Esmailzadeh E
Published: April 2011

A distributed dynamic vibration absorber with adaptive capability is presented to improve vibration suppression characteristics of harmonically excited structures. A double-ended cantilever beam carrying intermediate lumped masses forms the absorber subsection. The adaptive capability is achieved through concurrent adjustment of the positions of the moving masses, along the beam, to comply with the desired optimal performance. The necessary and sufficient conditions for the existence of periodic oscillatory behaviour, along with some physical bounds placed on the absorber parameters, form a constrained optimization problem for the optimum tuning strategy. Through numerical simulations it is shown that adaptive tuning is achieved by the variation of tuning mass locations such that the first-mode natural frequency is modulated on-line. The optimally tuned absorber provides considerable vibration suppression improvement over the passive and detuned absorbers.
Development of a multi-body simulation model of a Winston Cup valvetrain to study valve bounce
Authors: McLaughlin S , Haque I
Published: April 2011

Valvetrain dynamics is an important factor in the development of engines that operate at high rotational speeds. Valve bounce, which occurs at different speeds in the operating range of the engine, can severely limit the ability of the engine to develop peak power owing to the inability of the valves to seal appropriately. The objective of the work reported in this paper is to develop a model of a Winston Cup (WC) engine valvetrain that can predict the dynamics of the valvetrain at high speed. This model can then be used to develop a more complete understanding of the valvetrain motion and to aid effective design of valvetrains. The model is developed in the ADAMS environment. It contains a flexible pushrod, a flexible rocker arm and lift-off among all components, the mass of the valve springs, and a fluctuating rocker arm ratio. Also included in the model is damping in the valve spring and friction at the rocker arm pivot. Finite element analyses (FEAs) were conducted in order to obtain accurate data for pushrod and rocker arm stiffnesses, and to obtain the frequency response characteristics of the valve springs. The model data represent an actual engine used in WC racing. The model is run at different speeds to determine its dynamic characteristics and to verify its response with models developed previously by other researchers. Valve bounce predictions from the simulation model are compared with measured data from a Spintron test of an identical valvetrain configuration. The results indicate that the model accurately predicts the speeds of maximum valve bounce.
Optimization of the high-frequency torsional vibration of vehicle driveline systems using genetic algorithms
Authors: Farshidianfar A , Ebrahimi M , Rahnejat H , Menday M T , Moavenian M
Published: April 2011

Vehicle drivelines with manual transmissions are exposed to different dynamic engine torques under driving conditions. Engine torque can dramatically vary with throttle demand from coast to drive condition and, conversely, with throttle release from drive to coast. Abrupt application or release of throttle in slow moving traffic or rapid engagement of the clutch can be followed by an audible response, referred to in industry as the clonk noise. This paper presents a complete dynamic model of a vehicle driveline for the optimization of high-frequency torsional vibration by the distributed-lumped (hybrid) modelling technique (DLMT). The model used is first validated against experimental tests. Parameter sensitivity studies have been carried out using the model to identify the important components affecting clonk. Three key parameters have been chosen from the parameter study. To optimize these key factors, genetic algorithms (GAs) have been used in this multi-parameter optimization problem. The GAs show significant reduction in the driveline noise, vibration and harshness (NVH).
Computation of velocity in a plane joint, with application to the Tracta coupling
Authors: Fischer I S
Published: April 2011

A methodology designed for practical computer coding is developed to implement the velocity analysis of mechanisms with a plane joint, that is, a joint consisting of two flat surfaces held in contact to permit one rotational and two translational degrees of freedom. The analysis utilizes the 3 × 3 dual-number coordinate transformation modelling of joints and links of a mechanism to develop the results in a compact form amenable to object-oriented programming of displacement and velocity calculations. The velocity analysis of the Tracta coupling, an RRERR mechanism (rotation-rotation-plane-rotation-rotation joints) that has been used as a constant-velocity shaft coupling, is given as an example for a mechanism with a plane joint. An explanation is given of the relationship between the calculated speeds and the physical speeds in a plane joint.
Orthogonality conditions of the transverse vibration mode function for a stepped one-dimensional plate on a Winkler foundation and subjected to an in-plane force
Authors: Zhang Y S
Published: April 2011

The transverse vibration mode equation of a stepped one-dimensional plate on a Winkler foundation and subjected to an in-plane force is derived. The orthogonality conditions for transverse vibration of such a plate are obtained. The conclusions of this work can be used to solve the problem of forced vibration of various stepped one-dimensional plates, plates of constant thickness and beams.
Mechanical properties of cast aluminium alloy 6061-albite particulate composites
Authors: Seah K H W , Sharma S C , Ramesh A
Published: April 2011

This paper aims to study the effects of albite reinforcement on the mechanical properties of cast aluminium alloy 6061 composites containing albite particles of content ranging from 0 to 4 per cent by weight in steps of 1 per cent. The composites were fabricated using the ‘compo-casting’ method in which the short albite particulates were introduced into the vortex created in the molten alloy through an impeller rotated at 500 r/min. The results of this study revealed that, as the albite particle content was increased, there were significant increases in the ultimate tensile strength, hardness and Young's modulus, accompanied by a reduction in its ductility. There was, however, only a very marginal increase in the compressive strength. An attempt is made in the paper to provide explanations for these phenomena.
Europium-doped yttria-stabilized zirconia for high-temperature phosphor thermometry
Authors: Feist J P , Heyes A L
Published: April 2011

In this paper a study of the temperature-dependent luminescence properties of europium-doped yttria-stabilized zirconia (YSZ: Eu) powder are presented with a view to evaluating the potential of this material and lanthanide-doped YSZ generally for temperature measurement in the thermal barrier coating systems used in gas turbines. The time constant of the exponential emission decay occurring after ultraviolet excitation with a pulsed neodymium-doped yttrium aluminium garnet (YAG: Nd) laser was shown to be temperature dependent with a dynamic range from 26 to 800°C. Temperature dependence was observed for two distinct emission lines at 591 and 607 nm and the precision with which temperatures can be measured was estimated to be ±0.05 °C at the elevated temperature. The results demonstrate that YSZ: Eu can be considered as a thermographic phosphor and employed for temperature or heat flux measurements on surfaces in gas turbines or for monitoring purposes during coating production where the temperature is an important controlling parameter. Possible improvements in the measurement system to enhance its performance, the optimization of the YSZ: Eu formulation and the use of other lanthanides dopants are proposed for future work.
Numerical and experimental simulations of the dynamic behaviour of orthotropic plates
Authors: Mistou S , Sabarots M , Karama M
Published: April 2011

The study that has been carried out concerns the modal analysis of two multilayered orthotropic plates made of Rovimat and 290 g material Fabric, both glass fibre polyester materials. The Rovimat rectangular plate is clamped on all its edges whereas the Fabric 290 g rectangular plate is clamped on only one edge. Having first identified the mechanical properties of the two materials by ultrasonic characterization, the natural frequencies of the structure were then estimated with the help of the finite element computation software ANSYS and the analytical model (classical laminated plate theory). These results are then compared with experimental results, obtained using a fast Fourier transform analyser and an impact hammer.
Bonded metallic inserts for bolted joints in composite laminates
Authors: Camanho P P , Matthews F L
Published: April 2011

The use of adhesively bonded metallic inserts as a technique to improve the behaviour of bolted joints in composite laminates is investigated. A stress-failure analysis based on a three-dimensional finite element model including bolt-insert contact analysis, damage prediction in the laminate and the elastoplastic behaviour of the adhesive is performed. The effects of the insert material and thickness on the performance of the joint are determined. It is concluded that the use of bonded metallic inserts redistributes the stresses acting on the laminate's hole, thus reducing the stress concentration factors. However, for the configuration investigated, failure in the adhesive is predicted before the full strength of the laminate is used, and this effect can justify the experimental results, showing a small, if any, strength improvement when inserts are used.
A study of the reinforcement technology used to improve the life of mandrel bars used in seamless tube manufacturing by mandrel mill rolling
Authors: Akiyama M , Tsubouchi K , Hori H
Published: April 2011

Various heat treatments by induction heating were applied to the material of the mandrel bars used in the manufacturing of seamless tubes by mandrel mill rolling. The influence of experimental conditions was systematically examined, both using small-sized samples and at industrial scale. Within three distinct regions, delimited by a given combination of quenching and tempering temperatures, the toughness of the material could be significantly improved. When applied to mandrel bars in mandrel mill rolling, this actually resulted in longer service lives by preventing crack propagation in the vicinity of the surface. The cost of the new treatment is also lower than that of the conventional furnace heat treatment.
Geometric modelling of industrial preforms: Warp-knitted textiles
Authors: Robitaille F , Clayton B R , Long A C , Souter B J , Rudd C D
Published: April 2011

The processing properties of fibrous preforms and the final properties of liquid moulded composite parts are strongly related to the internal architecture of the preforms. The architecture of a preform is determined by the individual textile layers from which it is made. In order to calculate the processing and final properties in the same way over all the volume of a preform or part made from different types of textile, some sets of equations that generate similar definitions of the textiles from their manufacturing parameters are required. The similarity of these definitions is assessed through a series of criteria stated in a previous paper by the present authors; definition modules for woven and braided textiles were also presented in that paper. This paper presents a definition module, or a set of equations, that generates similar definitions for non-crimp reinforcements assembled by warp knitting; the equations also apply for the stitched threads used to assemble multiple-layer preforms. The definitions obtained from this module obey the criteria mentioned previously. The sets of equations presented in both papers cover most technical textiles; similar sets of equations can be created for speciality reinforcements and applied to the calculation of diverse physical properties of the preforms and parts. As an example, this paper discusses the mapping of the voids which are defined between the tows and threads of non-crimp stitched reinforcements.
Incorporating interlaminar fracture mechanics into design
Authors: Martin R H
Published: April 2011

In laminated composite structures, interlaminar failures or delaminations have continued to be a predominant life-limiting failure mode. The main concern for designers has focused on the damage tolerance of structures in the presence of delamination damage from impact events. The design approach has been to utilize existing stress/strain-based design criteria to design the part, then to impact the part consistent with the threat and to take a knock-down in design loads in the presence of damage. However, delaminations also occur during service in areas where high interlaminar stresses are present. These are generally at required discontinuities in the design, such as cut-outs, holes, joints or ply-drops. The application of interlaminar fracture mechanics as a design tool for optimizing these regions is still in its infancy and is adopted by very few original equipment manufacturers. This paper addresses this issue and presents the more recent developments in incorporating interlaminar fracture mechanics into design. The paper discusses the improvements in global-local modelling to integrate local design features with global stiffness and load considerations and vice versa. It will address the current methods for characterizing interlaminar fracture behaviour and show examples of how predictions can be made to predict the life of a component.
The design of twin-saddle supported multi-layered glass-reinforced plastic vessels—the development of a parametric equation for the maximum strain
Authors: Nash D H , Flaherty A E , Banks W M , Fok W C , Tooth A S
Published: April 2011

The maximum strain in a glass-reinforced plastic vessel, supported on rigid saddle supports, invariably occurs at the uppermost point of the support known as the saddle horn. The strain, which is in the circumferential direction, is compressive on the outside and tensile on the inside surfaces of the vessel. This can create problems in composite vessels since local cracking of the inner surface may allow liquid ingress to the glass through the matrix, with premature local failure by stress corrosion cracking. The analysis of this support problem has been solved using a double Fourier series by Tooth et al, [8], by which the maximum strain in the support region can be derived. The present paper presents a parametric study for an extensive range of vessels, in use in the process and chemical industries, using this analysis. To aid the design process the results for the crucial maximum strain values are presented in a ‘closed form’, using an equation-fitting technique. The details of the procedure used to achieve these equations should be of interest to analysts in other fields of work. Typical examples are given to illustrate the use of the derived equations for a symmetric laminate.