bluuebunny/crossref_metadata_2025 huggingface dataset:
Anxiety and Antisocial Behavior
Authors: Monahan Kathryn C. , Goldweber Aska , Meyer Kristen , Cauffman Elizabeth
Published: April 2011

The present study examines how perceptions of social prominence and attitudes toward antisocial behavior among peers moderate the association between anxiety and antisocial behavior among incarcerated females. Latent profile analysis identified two classes of females distinguished by their perceptions and attitudes. Individuals in both classes reported similar admiration of those who engage in antisocial behavior and similar desire to be perceived as such. Yet one group believed themselves to be socially prominent among peers and desired to be so (Socially Prominent group), whereas the other group was less likely to report, and desire, social prominence among peers (Socially Secondary group). Importantly, trait anxiety was related to greater antisocial behavior among socially secondary but not socially prominent females. Thus, in developmental periods when peers are salient, social prominence may be important for understanding why anxiety is associated with greater antisocial behavior for some females, but not others.
Linking Social Environments With the Well-being of Adolescents in Dual-Earner and Single Working Parent Families
Authors: Tisdale Sandee , Pitt-Catsuphes Marcie
Published: April 2011

This investigation examined the relationships between middle school-aged children’s perceptions of their social environments (home, school, neighborhood, and parental work) with self-reports of well-being. In the present study, well-being was defined by measures of physical health and psychological happiness. Data from the Nurturing Families Study were collected during in-person interviews with adolescents in dual-earner and single working parent families. Adolescents’ subjective assessments were analyzed through two hierarchical regression models: mothers’ ( N = 149) and fathers’ ( N = 150). Findings suggest that child gender, perceptions of the school environment, and parents coming home from work in a good mood significantly predict the variability in adolescent self-reports of well-being. The school environment was found to have the strongest predictive power over variations in adolescents’ well-being. Implications for practice and research, including improving supports within schools and focusing more attention on parental mood after work, are discussed.
Teenage Childbearing Among Youth Born to Teenage Mothers
Authors: Wildsmith Elizabeth , Manlove Jennifer , Jekielek Susan , Moore Kristin Anderson , Mincieli Lisa
Published: April 2011

Using data from the National Longitudinal Survey of Youth, this article examined how early maternal characteristics, an adolescent’s family environment, and the adolescent’s own attitudes and behaviors were associated with the odds of a nonmarital teenage birth among youth born to teenage mothers. Multivariate analyses indicated that these domains were closely linked. Early maternal characteristics shaped the later family environment of adolescents (parenting quality and home environment), which, in turn, was associated with the attitudes and behaviors of teens that put them at risk of a nonmarital birth. Notably, there was variation in some of the associations by gender. Increased mother’s cognitive ability lowered the risk of a nonmarital birth for boys, but not for girls, whereas fertility expectations were significant for girls, but not for boys. There were no race-ethnic differences in the risk of a teenage birth among girls, although Black boys had a higher risk than White boys.
High School Students’ Perceptions of Coping With Cyberbullying
Authors: Parris Leandra , Varjas Kris , Meyers Joel , Cutts Hayley
Published: April 2011

Cyberbullying can have a variety of negative effects on student mental health (Internet Safety Technical Task Force, 2008). An understanding of students’ coping with cyberbullying could help researchers and professionals to determine ways to alleviate and/or prevent the negative effects of cyberbullying. Qualitative methods were used to provide an in-depth examination of coping with cyberbullying. The results revealed three primary coping themes as follows: reactive coping, preventive coping, and no way to prevent cyberbullying. Reactive coping included avoiding the cyberbully situation by deleting or ignoring messages. Preventive coping strategies included talk in person and increased security and awareness. Some students reported that there was no way to reduce cyberbullying. These strategies were interpreted in terms of current theories of coping and findings suggested a need for a new comprehensive model of coping with cyberbullying. In addition, implications for future research and practice were discussed.
Where We Live
Authors: Francois Samantha , Overstreet Stacy , Cunningham Michael
Published: April 2011

Adolescents who live in low-income neighborhoods face numerous unique challenges. Examining their resilience in multiple contexts sheds light on what contributes to the diverse outcomes of these youth. The current study examines how adolescents’ reports of structural and experiential neighborhood characteristics buffered the impact of exposure to community violence on academic performance. A total of 206 African American high school students completed a series of questionnaires; some of the item measures covered by the questionnaires include the following: exposure to community violence; opportunities for involvement and actual engagement in neighborhood-based structured activities; and self-reported grades for the school year. Hierarchical multiple regression analyses revealed that structural and experiential factors buffered the impact of exposure to community violence on academic performance. These findings suggest that in the face of exposure to community violence, adolescents who are involved in neighborhood activities, even when opportunities for involvement are minimal, have better academic outcomes.
Bodily Deviations and Body Image in Adolescence
Authors: Vilhjalmsson Runar , Kristjansdottir Gudrun , Ward Dianne S.
Published: April 2011

Adolescents with unusually sized or shaped bodies may experience ridicule, rejection, or exclusion based on their negatively valued bodily characteristics. Such experiences can have negative consequences for a person’s image and evaluation of self. This study focuses on the relationship between bodily deviations and body image and is based on a national survey of 3,898 students attending 9th and 10th grade (age 14-16) in the Icelandic school system (92% response rate). Girls had a considerably lower body image than boys. Overweight and heaviness were related to lower body image among both genders. Interactions with gender showed that short stature was negatively related to body image among boys, whereas underweight was positively related to body image among girls. Bodily deviations can have positive implications, as shown by the fact that tall boys and girls had a more positive image of their body than their peers of lower stature. Theoretical and practical implications of these results are discussed.
Employment Status and Income Generation Among Homeless Young Adults
Authors: Ferguson Kristin M. , Bender Kimberly , Thompson Sanna J. , Maccio Elaine M. , Pollio David
Published: April 2011

This mixed-methods study identified correlates of unemployment among homeless young adults in five cities. Two hundred thirty-eight homeless young people from Los Angeles ( n = 50), Austin ( n = 50), Denver ( n = 50), New Orleans ( n = 50), and St. Louis ( n = 38) were recruited using comparable sampling strategies. Multivariate logistic regression results indicate that homeless young adults were more likely to be unemployed if they had been on the streets longer, currently lived on the streets, earned an income from panhandling, and were addicted to drugs. Quantitative findings are expanded on with focus-group data from a group of homeless young people in Los Angeles regarding their challenges in locating and maintaining employment. Employment-related barriers for this population include prior homelessness, geographic transience, previous felonies, mental illness, and addiction. Findings suggest that homeless young adults’ employment status and use of specific income-generating activities may be influenced by demographic, environmental, and geographic contexts.
Adult Perceptions of Neighborhood
Authors: Duke Naomi N. , Borowsky Iris W. , Pettingell Sandra L.
Published: April 2011

Context is important in facilitating healthy youth development. The purpose of this study was to examine the relationship between adult perception of neighborhood and youth engagement in organized activities. This study is a secondary data analysis of 64,076 parents and guardians of school-age youth and adolescents (6-17 years), participating in the 2007 National Survey of Children’s Health. Linear and logistic regression models were used to evaluate the relationship between neighborhood characteristics, including constructs for social capital, physical condition, resource availability, and safety, and youth engagement through participation in sports, clubs, other creative events, and volunteer service. Neighborhood characteristics were significantly associated with the odds of multiple forms of youth engagement even with adjustment for individual and family-level demographic characteristics. Findings support assessment of neighborhood context during health education and behavior counseling in addition to capacity building for deliberate mechanisms of community development offering youth the ability to connect and engage.
Child Maltreatment and Offending Behavior
Authors: Topitzes James , Mersky Joshua P. , Reynolds Arthur J.
Published: April 2011

This study assessed the association between child maltreatment (ages 0—11) and offending behavior within gender-specific models. Prospectively collected data, including official measures of maltreatment and offending, were derived from the Chicago Longitudinal Study, a panel study of 1,539 low-income minority participants. Multivariate probit analyses revealed that maltreatment significantly predicted delinquency for males but not females yet forged a significant relation to adult crime for both genders. Exploratory, confirmatory, and comparative analyses suggested that mechanisms linking maltreatment to adult crime primarily differed across gender. For males, childhood-era externalizing behavior and school commitment along with adolescent-era socioemotional skills, delinquency, and educational attainment explained the maltreatment-crime nexus. For females, childhood-era parent factors along with adolescent indicators of externalizing behavior, cognitive performance, mobility, and educational attainment partially mediated the maltreatment—crime relation. Implications of results were explored.
Cognitive Ability, Emotional Intelligence, and the Big Five Personality Dimensions as Predictors of Criminal Investigator Performance
Authors: Ono Masakatsu , Sachau Daniel A. , Deal William P. , Englert David R. , Taylor Michael D.
Published: April 2011

This study examines the extent to which cognitive ability, the Big Five factor personality dimensions, and emotional intelligence are related to training and job performance of U.S. federal criminal investigators. Training performance measures were collected during a 17-week training program. Job performance measures were collected 1 year after the investigators completed the training program. Conscientiousness was modestly related to training performance. Cognitive ability and emotional intelligence were positively correlated with job performance. Neuroticism was negatively correlated with job performance. The relative benefits of using emotional intelligence and the five-factor model to select law enforcement agents are discussed.
The Environmental and Situational Correlates of Victim Injury in Nonfatal Violent Incidents
Authors: Skubak Tillyer Marie , Miller J. Mitchell , Tillyer Rob
Published: April 2011

Previous research has documented several correlates of criminal victimization, but less is known about the factors related to victim injury during criminal events. Using environmental criminology to understand offender decision making during the criminal event, victim injury is explored with data from the National Incident Based Reporting System. Incident-level logistic and multinomial regression analyses were conducted to estimate the environmental and situational correlates of victim injury risk and severity in nonfatal violent events. Findings indicate that environmental and situational factors influence the likelihood and severity of victim injury, suggesting the utility of an environmental criminological approach for understanding not just the decision to offend but also offender behavior during criminal events.
Correlates of Correctional Orientation in a Treatment-Oriented Prison
Authors: Lambert Eric G. , Altheimer Irshad , Hogan Nancy L. , Barton-Bellessa Shannon M.
Published: April 2011

This exploratory study examined several propositions of person—environment fit theory in an adult midwestern correctional facility oriented toward treatment. Special attention was given to the manner that person—organization fit influenced correctional staff outcomes. Drawing from the need—supply fit framework of person—environment fit theory, the authors predicted that correctional staff whose values and objectives were congruent with those of the institution would experience better outcomes than staff whose values and objectives were not congruent. The results generally supported these propositions. Staff who supported punishment had higher levels of role stress and work—family conflict, had lower levels of life satisfaction and moral commitment, and were more likely to perceive the organization as unfair. Conversely, correctional staff who were supportive of treatment perceived higher levels of integration and had higher moral commitment. These results suggest that efforts to increase value congruence between staff and the institution will improve outcomes among correctional staff.
Sources of Variability in Estimates of Predictive Validity
Authors: Andrews D.A. , Bonta James , Wormith J. Stephen , Guzzo Lina , Brews Albert , Rettinger Jill , Rowe Rob
Published: April 2011

Level of Service (LS) is one of the most widely used general risk and need assessment tools in criminal justice agencies across North America. However, there is significant interstudy variability in the magnitude of the validity estimates. This study was conducted to examine possible sources of this variability. The predictive validity of LS risk and need increased with length of follow-up period and with investigator allegiance to LS. The combination of these two variables reveals consistent increases in mean predictive validity estimates from modest (in the .20s) through large (in the mid .30s) to very large (in the .40s) in samples of both male and female offenders. We hypothesized that the “allegiance effect” reflects the integrity of LS implementation and support provided by the agency for risk assessment. This is akin to the difference between “demonstration projects” and “practical” rehabilitation programming in the offender treatment research. Moreover, controls for Canadian versus non-Canadian evaluations reduced the effect of allegiance and length of follow-up to nonsignificant levels. Possible explanations for these findings include the degree of integrity in conducting risk and need assessments, the accuracy of recidivism as the criterion measure, and generalizability across international boundaries.
Choosing Among Residential Options
Authors: Caro Francis G. , Yee Christine , Levien Samantha , Gottlieb Alison S. , Winter Joachim , McFadden Daniel L. , Ho Teck H.
Published: April 2011

Older people who experience declining health are often faced with difficult decisions about possible residential relocation. The research aim was to determine how five distinct dimensions—functional status, features of current housing, social networks, features of retirement communities, and financial considerations—affect decisions to relocate to a retirement community. A vignette experiment with a factorial design was conducted involving both older people and adult children who were concerned with an aging parent. Use of the Internet for administration of the experiment made it possible to deliver information to research participants through video clips. Research participants were influenced by each of the dimensions; however, functional status of the vignette persons had the greatest impact, and financial considerations the least. Adult children were more likely to recommend moves than were older people. The research is suggestive of the potential for use of vignette experiments for a fuller understanding of relocation decisions.
How Money Matters
Authors: Usdansky Margaret L. , Parker Wendy M.
Published: April 2011

Using new data from the American Time Use Survey (ATUS), the authors consider how educational and parental status influence the relationship between wives’ relative earnings and the time they devote to housework in a climate of heightened gender egalitarianism and growing similarity between women’s and men’s time use. The authors capitalize on the large samples in the American Time Use Survey to study four groups of wives whose varying educational and parental statuses strengthen tests of theoretical claims regarding bargaining, gender display, and wives’ autonomy. Among wives with children at home and without a college degree, the authors find that relative earnings bear a curvilinear relationship to housework time, supporting predictions derived from exchange and gender display theories. Among wives with children and a college degree, and among wives without children regardless of degree status, relative earnings are unrelated to housework. In contrast, wives’ own earnings are inversely related to housework time across all four groups. The authors’ analyses suggest that educational and parental contexts jointly shape the relationship between wives’ earnings and their housework and the relative importance of bargaining, gender display, and autonomy.
SUNCT syndrome successfully treated by gamma knife radiosurgery: Case report
Authors: Effendi Khaled , Jarjoura Samir , Mathieu David
Published: April 2011

Background: The SUNCT syndrome (short-unilateral neuralgiform headache with conjunctival injection and tearing) can be very disabling for affected patients and is often refractory to medical management. We report the first case of SUNCT with a successful response to stereotactic radiosurgery without any adverse effect.

Case: After failing optimal medical treatment, a 82-year old male patient suffering from SUNCT syndrome was treated with Gamma knife radiosurgery. The trigeminal nerve and sphenopalatine ganglion were targeted with a maximum dose of 80 Gy each. The patient had complete pain cessation 2 weeks after the treatment, and remains pain-free with no medication at the latest follow-up 39 months after radiosurgery. He did not have any side effect from the procedure.

Conclusion: Gamma knife radiosurgery is an option for medically refractory SUNCT patients.
Biomechanical Analysis of Chlorhexidine Power Irrigation to Disinfect Contaminated Anterior Cruciate Ligament Grafts
Authors: Han Yung , Giannitsios Demetri , Duke Kajsa , Steffen Thomas , Burman Mark
Published: April 2011

Background: Accidental graft contamination is a likely complication to occur in an orthopaedic sports medicine surgeon’s career. There are no clinical outcome studies to direct management, and a recent survey showed that preferred management varied. Three liters of 2% chlorhexidine power irrigation has been shown to be an efficient and effective disinfection protocol; however, the biomechanical sequelae of this disinfection protocol to the graft are unknown.

Purpose: The purpose of this study was to determine if 3 L of 2% chlorhexidine power irrigation used to disinfect contaminated anterior cruciate ligament (ACL) grafts significantly weakens the graft at time zero.

Study Design: Controlled laboratory study.

Methods: Eight fresh bovine superficial digital flexor tendons underwent disinfection protocol with 3 L of 2% chlorhexidine power irrigation. Contralateral tendons served as the control. Tendons were preconditioned and loaded to failure.

Results: The average ultimate failure load for the control tendons and disinfected tendons was 4081 ± 654.4 N and 4146 ± 723.2 N, respectively. The average ultimate failure stress for the control tendons and disinfected tendons was 97.10 ± 12.03 MPa and 95.18 ± 11.79 MPa, respectively. The average stiffness for the control tendons and disinfected tendons was 546.20 ± 28.16 N/mm and 539.2 ± 25.93 N/mm, respectively. The P values for ultimate failure load, ultimate failure stress, and stiffness showed no statistically significant difference between the chlorhexidine and control tendons.

Conclusion: Disinfecting tendons with 3 L of 2% chlorhexidine power irrigation does not adversely weaken the tendon’s tensile mechanical properties.

Clinical Relevance: Three liters of 2% chlorhexidine power irrigation can effectively disinfect a contaminated ACL graft without weakening the graft.
Some comments on ‘Investigative study on machinability aspects of unreinforced and reinforced PEEK composite machining using ANN model’
Authors: Sha W.
Published: April 2011

This short article comments on two papers using artificial neural networks published in composites journals. The issues discussed include the predictive capability of the neural networks developed, and the size of the databases for training the neural networks. The article includes criticisms of those previously published papers.
Cutting-Edge
Authors: Hafner Dedra , Moffatt Courtney , Kisa Nutullah
Published: April 2011

Cutting-Edge provides inclusion in college for students with intellectual disabilities (SWID). Cutting-Edge students attended college by taking undergraduate courses, resided in student housing, and engaged in student-life events as well as pursued community service, internships and employment. Undergraduate students were the best means to teach Cutting-Edge students about appropriate social activities and interactions. Undergraduate students were paired with Cutting-Edge students as peer mentors to teach Cutting-Edge students how to fit into the social network on campus. While attending the college, 79% of Cutting-Edge students lived away from their parents. Undergraduate students were surveyed about how comfortable they feel about being around SWID, and 96% indicated they either felt comfortable (59%) or very comfortable (37%).
Twenty Years After
Authors: Waisová Šárka , Piknerová Linda
Published: April 2011

However obsolete it may appear in the environment of the post-1989 Czech Republic, dissident activity has left its imprint on Czech society and politics. In Czech foreign policy, there is something like a dissident tradition, which dissidents themselves seem to uphold. In the Czech foreign policy process, there exists an explicit mechanism that has incorporated the dissident tradition, which, in quite a few cases, has affected policy outcomes. The introduction of the dissident tradition into Czech foreign policy was facilitated by the dissidents’ great concern for foreign policy and for human rights issues, and, in particular, for human rights issues outside the Czech Republic. We present evidence that dissidents have been concerned with foreign policy and with human rights issues by analyzing the membership of parliamentary committees of both chambers of the Parliament as well as the dissidents’ activities in the Senate and the Chamber of Deputies. Significantly, when activities tied to the dissident tradition emerge in the Parliament, the initiators of such activities are always (although not exclusively) dissidents; the opponents, always nondissidents.
Blue-Collar Discourses of Workplace Dignity: Using Outgroup Comparisons to Construct Positive Identities
Authors: Lucas Kristen
Published: April 2011

People generally possess a strong desire to construct positive, dignified work identities. However, this goal may be more challenging for some people, such as blue-collar workers, whose occupations may not offer qualities typically associated with workplace dignity. Interviews with 37 people from a blue-collar mining community reveal three central identity discourses about workplace dignity: All jobs are important and valuable; dignity is located in the quality of the job performed; and dignity emerges from the way people treat and are treated by others. Participants communicated these themes by backgrounding their own occupations and drawing comparisons between two outgroups, low-status, low-paid dirty workers and high-prestige, white-collar professionals. Implications for understanding how identity work is negotiated and for managing a blue-collar workforce are explained.
Talking Up Failure: How Discourse Can Signal Failure to Change
Authors: Schwarz Gavin M. , Watson Bernadette M. , Callan Victor J.
Published: April 2011

This article explores the predictive properties of talk as an indicator of failure to change. As part of the exploration of organizational change, researchers regularly focus on how discourse is used and applied to achieve certain processes and outcomes. This position presents change as a function of particular types of communication and its interpretation. Using longitudinal data of an organization’s technology change, we propose that the way employees talk about planned organizational change, as a group, signals and can be used to recognize eventual failure to change. Extending current trends in discursive analyses, we establish talk as a reflective device, in the context of tracking failure while it occurs, by combining social identity theory (SIT) with a language and social psychology (LASP) approach. In doing so, the discourse of failure can be viewed as part of an intergroup phenomenon experienced and interpreted through organizational memberships.
Condition monitoring of mechanical seals: Detection of film collapse using reflected ultrasonic waves
Authors: Anderson D , Jarzynski J , Salant R. F.
Published: April 2011

A method for detecting the collapse of the lubricating film in a mechanical seal has been developed. A piezoelectric transducer is placed behind the non-rotating seal face and is used to generate ultrasonic waves, which propagate towards the interface between the two seal faces. The same transducer is used to detect the reflected waves, whose amplitude is a measure of the degree of contact between the faces. The results of bench tests, steady-state tests and transient tests show that the method is effective.
Invariant measures of the closeness to linear dependence of six lines or screws
Authors: Hartley D M , Kerr D R
Published: April 2011

Line and screw systems, used in robotics and machinery analysis, become singular at particular geometric configurations. When not singular, measures are required that describe how far they are from being so. A new system of measures is proposed whose outcome is strictly invariant with respect to coordinate frame, origin and unit of length. Examples of the application of the new measures to sixfold systems of lines and screws in the context of work-holding systems and robotic manipulators are given.
Unique design of the junction between a thick pressure vessel shell and a thinner hemispherical head
Authors: Zheng J , Sun G , Chen Z , Xu P , Liu A , Liu Y
Published: April 2011

Considering the fact that the required thickness of a hemispherical head for pressure loading is only half of that necessary for a cylindrical shell, the authors have developed a proprietary junction of shell to hemispherical head where the head is thinner than the shell. In the past 5 years, more than 100 high-pressure vessels with such junctions have been manufactured and safely used in the People's Republic of China. Theoretical investigations as well as engineering applications show that such junctions are rational in structure, convenient in fabrication and low in cost. For example, for a vessel with an inner diameter of 1000 mm and design pressure of 31.4 MPa, using the new junction, the head weight is reduced by 54.3 and 27.4 per cent respectively in comparison with a forged flat head and a hemispherical head with equal thickness of shell. The larger the vessel, the greater the economic benefits it achieves. In this paper, the authors describe its basic structure, stress characteristics and the engineering design method for the unique junction.
Transient analysis of isothermal elastohydrodynamic circular point contacts
Authors: Vahid D Jalali , Rahnejat H , Jin Z M , Downson D
Published: April 2011

In this paper a solution method is presented for the transient isothermal elastohydrodynamic lubrication of point contact conjunctions, based upon the Newton-Raphson scheme and low iteration relaxation. The numerical results are compared with the numerical and experimental observations of others for the circular point contact of a ball against a flat glass disc under oscillating conditions. Good agreement has been found with other numerical solutions. The comparison with the experimental results shows good qualitative agreement.
Bearing contact of a helical gear pair with involute teeth pinion and modified circular-arc teeth gear
Authors: Chen Y-C , Tsay C-B
Published: April 2011

This paper investigates the contact ellipse of a helical gear set, composed of an involute pinion and a modified circular-arc gear based on curvature analysis. This gear drive exhibits point contact and parabolic transmission error due to the double crowning effect of the gear, i.e. crowning in both profile and longitudinal directions. The principal directions and curvatures of the generating tool surfaces were derived by means of differential geometry and Rodrigues’ equation. The principal directions and curvatures of the pinion and gear surfaces were obtained directly from the generating surfaces. Finally, the determination of the contact ellipses of the mating tooth surfaces was achieved. Numerical examples are also provided to demonstrate the computational results.
Analysis of liquid outflow from single-outlet vessels
Authors: Koukouvaos A , Kubie J
Published: April 2011

The paper presents experimental and theoretical investigation of the outflow of liquids from single-outlet vessels incorporating a vertical downcomer. In such vessels the liquid leaving through the outlet of the downcomer is replaced by another fluid, which enters the vessel-downcomer system through the same opening. Experimental results of the variation of the void fraction and pressure in the vessel with elapsed time are presented. It is shown that the flow is generally oscillatory, and the conditions required for the establishment of the fully developed oscillatory flow are reported. A theoretical model of the fully developed oscillatory flow is developed. The model describes well the frequency of the oscillatory flow and the variation of the gas void fraction in the vessel with elapsed time. The model somewhat overpredicts the amplitude of the pressure oscillations. Thermodynamic aspects of this flow are also considered.
The mechanics of an oscillatory rate gyroscope with piezoelectric film actuation and sensing
Authors: Royle C M , Fox C H J
Published: April 2011

Many applications exist for low-cost, miniature rate gyroscopes. These are primarily in the automotive field, and relate to safety systems or vehicle navigation. This paper presents an analysis of the mechanics of an oscillatory rate gyroscope that is actuated and sensed using thin-film lead-zirconate-titanate (PZT), and is suitable for manufacture using recently developed micromachining techniques. An analytical model of the device, combining the electromechanical behaviour of PZT and the dynamic behaviour of the mechanical structure, has been developed. This model is used to investigate the basic performance of a gyro of realistic dimensions, thus demonstrating the potential feasibility of such a device.
On the transmission efficiency of a spring-type operating kinematic mechanism for an SF6 gas-insulated circuit breaker
Authors: Chen F-C , Hsu M-H
Published: April 2011

The purpose of this paper is to study the transmission efficiency of a spring-type operating kinematic mechanism for an SF6 gas-insulated circuit breaker. This mechanism has two degrees of freedom, which, when operating in the open, close, or return mode, becomes a single degree of freedom by fixing a link that adjoins the frame to achieve specific requirements. Firstly, the vector-loop method is employed for position analysis of the links of the mechanism. Subsequently, by using coordinate transformation and the geometry of the cam and the follower, the relationships between cam rotation and the position of the linkage follower in the close operation, as well as cam rotation and the position of the motor-switch follower are established. Based on the transmission angle of the linkage and the pressure angle of the cam mechanism, the transmission efficiencies of the mechanism are evaluated and discussed. The mechanism is also computer simulated and the transmission angle is optimized using the augmented Lagrange multiplier (ALM) method. The results show that the optimized parameters noticeably improve the transmission angles of the present design.
Elastic displacement of the surface due to a laser heating pulse
Authors: Yilbas B S , Shuja S Z , Arif A F M
Published: April 2011

When the surface of a substrate material is heated by a laser pulse, the surface initially expands and then contracts after the laser heating pulse ends. This may allow the surface temperature to be measured by monitoring the surface displacement. In the present study, the elastic displacement of the surface due to the temperature field generated during a laser heating pulse is examined. Three-dimensional laser gas-assisted heating is considered and the governing equations of flow and energy are solved numerically using a control volume approach, while the elastic displacement of the surface due to the temperature field is modelled through the finite element method. The relationship between the temperature rise and the elastic thermal displacement is discussed in detail. It is found that the rate of thermal expansion of the surface in the heating cycle is not the same as the rate of thermal contraction in the cooling cycle. Moreover, in the heating cycle, the rate of temperature rise and the rate of thermal expansion are similar.
A comparison of the experimental and computational modelling of the fluidic turn-up vortex amplifier at full and zero swirl conditions
Authors: Woolhouse R. J. , Tippetts J. R. , Beck S. B. M.
Published: April 2011

The design and operation of a novel type of fluidic vortex amplifier have been investigated experimentally using model tests with ambient air, and using computationally time-dependent computational fluid dynamics (CFD) simulation. The ultimate objective is to develop a no-moving-part variable air distribution device for implementation within gas turbine combustors using the fuel flow as the controlling agent. Although both liquid and gaseous fuels are ultimate goals of this device, this paper describes the first stage of the work involving operation with nominally uniform density fluid (air).

There is some discrepancy between the simulation and test data, but design and performance trends were usefully simulated. An important feature of the CFD was the occurrence of a weak time dependent flow structure, particularly with the Reynolds stress model (RSM). Flow modulation within the desired range (4.5 compared with 2.6) was demonstrated, and these are shown, along with some general points concerning computational modelling convergence and turbulence models.
Monitoring wood decay in poles by the vibroacoustic response method
Authors: Craighead I. A. , Thackery S , Redstall M , Thomas M. R.
Published: April 2011

Despite recent advances in the development of new materials, wood continues to be used globally for the support of overhead cable networks used by telecommunications and electrical utility companies. As a natural material, wood is subject to decay and will eventually fail, causing disruption to services and danger to public and company personnel.

The traditional method of testing poles for decay involves hitting them with a hammer and listening to the sound that results. However, evidence suggests that a large number of poles are replaced unnecessarily and a significant number of poles continue to fail unexpectedly in service. Therefore, a more accurate method for assessing the structural integrity of wooden poles is required. The underlying physical principles behind the ‘pole tester's approach’ have been identified and used in the development of a decay meter to enable objective monitoring of decay in wooden poles.
An artificial neural network module for simulation of the energy storage system of a hybrid electric vehicle
Authors: Bhatikar S. R. , Mahajan R. L. , Wipke K , Johnson V
Published: April 2011

A hybrid electric vehicle (HEV) is a complex system integrating interactive subsystems of disparate degrees of complexity. The simulation of an HEV thus poses a challenge. An accurate simulation requires highly accurate models of each subsystem. Without these, the system has a poor overall performance. Typically, modelling problems are not amenable to physical solutions without simplifying assumptions that impair their accuracy. Conventional empirical models, on the other hand, are time consuming and data intensive and falter where extensive non-linearity is encountered. An artificial neural network (ANN) approach to simulation of an HEV is presented in this paper. An ANN model of the energy storage system (ESS) of an HEV was deployed in the ADVISOR simulation software developed by the National Renewable Energy Laboratories (NREL) of the US Department of Energy. The ANN model mapped the state of charge (SOC) and the power requirement of the vehicle to the voltage and current at the ESS output An ANN model was able accurately to capture the complex, non-linear phenomena underlying the ESS.

A novel performance-enhancing technique for design of ANN training data, Smart Select, is described here. It resulted in a model of 0.9978 correlation (R2 error) with data. ANNs can be data hungry. The issue of knowledge sharing between ANN models to save development time and effort is also addressed in this paper. The model transfer technique presents a way of levering the expertise of one ANN into the development of another for a similar modelling task. Lastly, integration of the ANN model of the ESS into the ADVISOR software, on the MATLAB software platform, is described.
The flow through a plenum-runner system—a comparison of experiment and computation
Authors: Shaw C. T. , Lee D. J. , Richardson S. H. , Pierson S
Published: April 2011

This paper describes the comparison between experimental and computational results for the flow in an inlet system that contains a plenum. Here, the main focus is on the details of the computations and the comparison with experimental results for flow in the plenum. Details of the experiment are described elsewhere. By varying mesh density, boundary conditions, discretization schemes and turbulence models, a wide-ranging study of the accuracy of computational techniques for an industrial problem has been made. In particular, levels of mesh refinement for converged numerical solutions have been determined, together with performance levels for the various settings used. In terms of velocity prediction, when the flow is driven by boundary conditions specified at the outlet more accurate results are achieved. This is due to the flow at the inlet being calculated more accurately in these cases. The effects of different discretization schemes and turbulence models on the velocity predictions are small. Pressure predictions are, however, improved by more complex turbulence models such as the renormalization group (RNG) model.
Design of a load cell for measuring ultrasonic percussive drilling forces
Authors: Loong V K-S , Wojewoda J , Wiercigroch M
Published: April 2011

In this article a novel design of a load cell for the measurement of highly dynamic forces generated during high-frequency percussive drilling is presented. It allows for a high-volume accurate measurement of low-amplitude and high-frequency (ultrasonic) dynamic forces while retaining high mechanical stiffness. The load cell consists of three piezotransducers mounted between the base and the top disc. To achieve a required level of signal synchronization between the signals from individual transducers, the piezotransducers are appropriately preloaded. The paper discusses the design procedure, instrumentation set-up and sample experimental measurements.
Thermal stress effects on the surface durability of gear teeth
Authors: Seireg A
Published: April 2011

The current standards and design relationships for the surface durability of gears are based on contact stress considerations. Thermal effects are considered only for scoring failures resulting from the destruction of the lubricating film owing to temperature rise. This paper investigates the effect of thermal shock and thermal stress cycling on pitting, micropitting and wear for different gear geometries, materials, operating conditions, machining processes and surface treatments. Because of the current interest in applying surface coating technology to gears, special attention is given to illustrating the potential benefits of this technology in improving the performance and extending the life of gears.
Accuracy of small encoders for gear transmission errors
Authors: Smith J. D.
Published: April 2011

For noise investigations and development work or precision production control of gear drives there are major advantages to using small encoders for transmission error measurement in situ owing to reduced size, inertias and cost. As there was uncertainty concerning the accuracies that would be obtained in practice, a small encoder was calibrated and found to be surprisingly accurate at those frequencies of importance for gear noise.
Analysis of transitional flow and heat transfer over turbine blades: Algebraic versus low-Reynolds-number turbulence model
Authors: Sarkar S
Published: April 2011

The numerical simulation of flow and heat transfer over turbine blades involving laminar-turbulent transition is presented. The predicted results are compared with the experimental surface heat transfer and pressure distributions for two transonic turbine blades over a wide range of flow conditions. The time-dependent, mass-averaged Navier-Stokes equations are solved by an explicit four-stage Runge-Kutta scheme in the finite volume formulation. Local time stepping, variable-coefficient implicit residual smoothing and a full multigrid method have been implemented to accelerate the steady state calculation. The turbulence is simulated by the algebraic Baldwin-Lomax model together with an explicitly imposed model for transition. For comparison, the low-Reynolds-number version of the two-equation ( k-∊) model of Chien is also used. The modified Baldwin-Lomax model performs well in predicting the onset of laminar-turbulent transition, whereas the Chien model shows a tendency to mimic the transition early and over a shorter distance.
Two-dimensional pressure control valve
Authors: Ruan J , Burton R , Ukrainetz P , Xu Y. M.
Published: April 2011

The two-dimensional pressure control valve is a piloted control valve which functions by using both linear and rotary motions of a single spool. A groove on the spool land, incorporating a sensing channel, forms the pilot stage to control the pressure of a spool chamber, while the load pressure is fed to the other spool chamber. To sustain the balance of the force across the spool, the load pressure must follow the change of pressure variation along the groove while the spool is in rotary motion. The geometric parameters of the groove and the spool-to-sleeve clearance have significant effects on both the static and dynamic characteristics of the valve. Increasing the sectional size of the groove results in a large Reynolds number and the static property of the valve thus changes from that of linearity owing to the entrance effect. The linearity of the static property is also affected by the leakage through the spool-to-sleeve clearance. The dynamic characteristics of the valve are dependent upon both the structural parameters and the tune constant of the load. The stability and dynamic response were investigated under different structural parameters and time constants of the load using both linear theory and simulation methods. Experiments were designed to obtain the static and dynamic characteristics of the valve and the leakage through the pilot. A balance should be made between the linearity of the static property and the response speed; it was found that both fairly linear static and desired dynamic characteristics could be simultaneously maintained for the two-dimensional pressure control valve.
Static follower problem revisited
Authors: Genin J
Published: April 2011

Using an energy technique, the classical solution for the static formulation of the tangential follower problem is reproduced considering the more general case of a column with variable stiffness. The method of solution allows for a more delicate analysis of the phenomena associated with this problem. It is shown that the classical problem is, in a sense, overdetermined. The problem is then reformulated to permit the existence of critical loads for the static case.
Soot temperature and concentration measurements from colour charge coupled device camera images using a three-colour method
Authors: Simonini S , Elston S. J. , Stone C. R.
Published: April 2011

The three-colour method has been developed in order to turn chromatic information in charge coupled device (CCD) camera images of combustion into flame temperature and soot concentration measurements. The method showed the following advantages over the two-colour method from which it is derived: only one camera is needed; no further calibration is required once the response curve of the camera is known; it does not rely on light intensity but on ratios between colour components, making it easy to adapt to different operating points with different name brightness. The results on temperature evaluation were compared with a thermodynamic model, and better agreement was found in the late stages of the cycle, when the radiation from chemical reactions becomes negligible. The error analysis showed that the calculations for soot concentration are ill-conditioned, but when the results are integrated to give a soot loading the accuracy is improved and there is clear evidence of soot evolution and destruction during combustion.
Identification of rotating asymmetry in rotating machines by using reverse directional frequency response functions
Authors: Lee C-W , Kwon K-S
Published: April 2011

A quick and easy but comprehensive identification method for rotating asymmetry in rotating machines is proposed, based on the complex modal testing method. In this work it is shown that the reverse directional frequency response function (reverse dFRF), which indicates the degree of asymmetry, can be identified with a simple testing method requiring only a single vibration sensor and a single exciter. To clarify physical realization associated with estimation of the reverse dFRF, its relation to the conventional frequency response functions, which are defined by the real input (excitation) and output (vibration measurement), are discussed extensively.