36 research outputs found
Lubrication in cold rolling: Elasto-plasto-hydrodynamic lubrication
A model has been developed with respect to hydrodynamic lubrication in cold rolling. The basic model describes the configuration of a rigid, perfectly plastic sheet rolled by a rigid work roll. The governing equations have been solved throughout the complete contact area, i.e. the inlet, the work zone and the outlet zone. Multi-level techniques have been applied to solve these equations together with boundary conditions, resulting in an algorithm solving the problem in O(n) operations. This means that the distribution of the pressure and the traction force in the lubricant film, and the shape of this film, as well as the plastic deformation of the sheet, can be accurately calculated for a large number of nodal points on a minicomputer. Subsequently elastic deformation, work hardening and dynamic behaviour of the flow stress have been incorporated in the model. It will be shown that the influence of these effects on the film thickness or the pressure distribution is considerable
Minder uitval na thermische analyse van lagers; EEM-berekeningenoptimaliseren standtijd rollenbaanlagers
Parental Smoking and Adolescent Smoking Stages: The Role of Parents' Current and Former Smoking, and Family Structure
This study examined the role of parents’ current and former smoking in predicting adolescent smoking acquisition stages. Participants were 7,426 students from 33 schools in the Netherlands. Participants’ survey data were gathered at baseline and at two-year follow-up. Logistic regression models showed that parental smoking status was not only predictive of transitions from never smoking to trying smoking, monthly smoking, or daily smoking, but also of the progression from trying smoking to daily smoking. Further, although parental former smoking was weaker associated with progressive adolescent smoking transitions than current parental smoking, however absence of parental smoking history was most preventive. Compared to the situation in which both parents had never smoked, cessation of parental smoking after the child was born was associated with an increased risk for children to smoke. Adolescents living in a single-parent family were at greater risk of smoking than adolescents living in an intact family with both mother and father. In sum, the role of parental smoking is not restricted to smoking onset and is present throughout different phases of the acquisition process. Results support the delayed modeling hypothesis that parental smoking affects the likelihood for children to smoke even when parents quit many years before. Children living in single-parent families are only exposed to the behaviour of one parent; in two-parent families the behaviour from one parent may magnify or buffer the behaviour of the other parent
Adolescent Psychological and Social Predictors of Young Adult Smoking Acquisition and Cessation: A 10-Year Longitudinal Study
Item does not contain fulltextObjective: A 10-year follow-up study to test the extent to which theory-based adolescent psychological and social factors directly predict and moderate the prediction of young adult smoking acquisition and cessation. Design: A prospective community-based sample. A total of 2,970 adolescents participated in the large Washington State Hutchinson Smoking Prevention Project (HSPP) longitudinal cohort. As predictors, psychological factors (i.e., parentnoncompliance, friendcompliance, rebelliousness, achievement motivation, and thrill seeking) and social environmental factors (i.e., parent's and friend's smoking) were measured when adolescents were 17-18 years old. Main Outcome Measures: As main outcome measures, smoking acquisition and cessation were assessed both at ages 18 and 28. Results: Psychological and social factors predicted 3% to 7% probability (p < .05) of smoking acquisition and a nonsignificant to 24% probability (p < .05) of smoking continuation (not quitting) in young adulthood. Both friendcompliance and rebelliousness were more powerful predictors of young adult-smoking continuation than of smoking acquisition. Conclusion: First evidence that parent noncompliance, friend compliance, and a lack of achievement motivation predict smoking acquisition and (with the exception of parent noncompliance) smoking continuation in young adulthood. Including these psychological factors in future interventions designed to promote young adult smoking cessation may be useful
Window Matching using Sparse Templates
This report describes a novel window matching technique. We perform window matching by transforming image data into sparse features, and apply a computationally efficient matching technique in the sparse feature space. The gain in execution time for the matching is roughly 10 times compared to full window matching techniques such as SSD, but the total execution time for the matching also involves an edge filtering step. Since the edge responses may be used for matching of several regions, the proposed matching technique is increasingly advantageous when the number of regions to keep track of increases, and when the size of the search window increases. The technique is used in a real-time ego-motion estimation system in the WITAS project. Ego-motion is estimated by tracking of a set of structure points, i.e. regions that do not have the aperture problem. Comparisons with SSD, with regard to speed and accuracy are made
Promoting smoking cessation among parents: Effects on smoking-related cognitions and smoking initiation in children
Item does not contain fulltextBackground
Parental smoking is associated with an increased risk of smoking among youth. Epidemiological research has shown that parental smoking cessation can attenuate this risk. This study examined whether telephone counselling for parents and subsequent parental smoking cessation affect smoking-related cognitions and smoking initiation among children of smoking parents.
Methods
Data of a two-arm randomized controlled trial were used in which 512 smoking parents were recruited into cessation support through their children's primary schools. After the baseline assessment, smoking parents were randomly assigned to tailored telephone counselling or a standard self-help brochure. Parental cessation was measured as 6-month prolonged abstinence at the 12-month follow-up. Children's smoking-related cognitions and smoking initiation were examined at 3-month, 12-month, and 30-month follow-up.
Results
No statistical evidence was found that children of parents who received telephone counselling tailored to smoking parents or children of parents who achieved prolonged abstinence differ in smoking-related cognitions (i.e., smoking outcome expectancies, perceived safety of smoking, self-efficacy to refrain from smoking, susceptibility to smoking) or smoking initiation rate on any follow-up assessment.
Conclusions
This study is the first to examine the effects of an evidence-based smoking cessation treatment for parents and treatment-induced parental smoking cessation on cognitive and behavioural outcomes among children. Although descriptive statistics showed lower smoking initiation rates among children of parents who achieved prolonged abstinence, there was no statistical evidence that telephone counselling tailored to parents or treatment-induced parental smoking cessation affects precursors of smoking or smoking initiation among youth
Self-efficacy and acceptance of cravings to smoke underlie the effectiveness of quitline counseling for smoking cessation
Background: Few studies have examined why smoking cessation interventions are effective. The aim of this study was to examine the mediating processes underlying the effectiveness of cessation counseling administered by the Dutch national quitline.
Methods: Data were used of a two-arm randomized controlled trial in which smoking parents, who were recruited through primary schools in The Netherlands, received either quitline cessation counseling (n = 256) or a self-help brochure (n =256). The endpoint was 6-months prolonged abstinence at 12-months follow-up, with 86.7% outcome data retention. Putative psychological mediators of treatment effectiveness included smoking-related cognitions (positive smoking outcome expectancies, self-efficacy), emotions (negative affect, perceived stress, depressive symptoms), and smoking cue coping methods (avoidance coping, acceptance coping) assessed at 3-months post-measurement.
Results : Quitline cessation counseling significantly decreased positive smoking outcome expectancies and negative affect and increased self-efficacy to refrain from smoking, avoidance of external cues to smoking, and acceptance of internal cues to smoking compared to self-help material. Increased self-efficacy to refrain from smoking in stressful and tempting situations (p < .001) and increased acceptance of cravings to smoke (p < .001) significantly mediated the effect of quitline cessation counseling on prolonged abstinence at 12-months follow-up (explained variance: 25.1%).
Conclusions: Self-efficacy to refrain from smoking and acceptance of cravings represent an important source of therapeutic change in smoking cessation counseling
Effectiviteit van telefonische coaching om te stoppen met roken
Item does not contain fulltextWe tested the effectiveness of tailored quitline (telephone) counselling among smoking parents recruited into cessation support through their children’s primary schools. We conducted a two-arm randomized controlled trial with 3-month and 12-month follow- up. Smoking parents were recruited through their children’s primary schools and received either quitline counseling in combination with tailored supplementary materials or a standard self-help brochure. Parents who received quitline counseling were more likely to report 7-day point prevalence abstinence at 12month assessment than those who received a standard self-help brochure. Parents who received quitline counseling were more likely to use nicotine replacement therapy than those who received a standard self-help brochure. Among parents who did not achieve abstinence, those who received quitline counseling smoked fewer cigarettes at 3-months assessment and 12-month assessment, were more likely to make a quit attempt, to achieve 24hours abstinence, and to implement a complete home smoking ban than those who received a standard self-help brochure. Quit-line counseling tailored to smoking parents is an effective method for helping parents quit smoking and promoting parenting practices that protect their children from adverse effects of smoking