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The influence of the machine specific instantaneous current wave forms on weld nugget dimensions and weld strength is investigated over six spot welding machines. It is observed that the nature of the real-time current wave forms corresponding to a common rms value can vary in different ac spot welding machines. The variations exist in the values of peak current and in the current-on and -off times in every ac cycle. It is observed that real-time current wave form involving higher peak current leads to slightly larger weld nugget diameter compared to wave form with smaller peak current even if the overall rms value remains similar The real-time current wave form from a medium frequency dc confirms to a fast rise to the set weld current and remains steady for the complete weld time. A detailed experimental study has depicted that the real-time ac wave forms especially with high peak values and sharp rise characteristics offer a relatively smaller permissible range of weld currents compared to the wave forms with relatively flatter characteristics. The steady instantaneous current wave form confirming to the medium frequency dc machine has facilitated a larger permissible range of weld current. A numerical analysis of the spot welding process based on finite element process is carried out using both the instantaneous current wave forms and the corresponding rms values of weld current. The predicted weld dimensions using instantaneous current wave forms have showed slightly better agreement with the corresponding measured weld dimensions. Keywords: resistance spot welding, instantaneous current wave form, AC and DC welding machines, numerical modeling

The driving behaviour inventory was developed to assess the extent of stress drivers experience. Parameters such as attitudes, anxiety and aggression, human factors in accidents and decision-making styles were used in the survey. Sixty one respondents were involved in the study in the course of five months. The results of the study would be advantageous not only to drivers who ride daily to work, but also for whom driving is a profession. It also has potential use for driving educators, counsellors, therapists, safety engineers, psychologists and automobile ergonomists.

It is argued that the reason that previous evidence apparently did not support the accident proneness hypothesis was faulty methodology and erroneous interpretations of results. Between time periods correlations of traffic accident records actually show an impressive stability over time when restriction of variance is controlled for. However, stability can be caused by stable differences in exposure. Correlations of accident records between time periods were analysed comparing full time and part-time bus drivers. For drivers who worked full time, the amount of exposure was held semi-constant while part-time drivers could be expected to work differing hours. If differential exposure causes stability in crash record, then part-time drivers should yield stronger correlations between time periods for crashes compared with full-time drivers. Between time periods accident correlations for part-time drivers were weaker than the corresponding ones for full time drivers. Correlations increased with increasing variance in the data. Results for all crashes fit in well with other meta-data, while culpable crashes did not, probably due to faulty coding. The current results support the notion of the tendency to cause traffic accidents as a stable trait within individuals as this is apparently not caused by stable differences in exposure. [ABSTRACT FROM AUTHOR]

To avoid potentially fatal wrong-route neuraxial drug errors, international standard ISO 80369-6 specifying a non-Luer neuraxial connector design was published in 2016. We describe usability studies used in development of the design. Thirty-eight doctors and 17 nurses performed simulated procedures on manikins, using devices fitted with Luer connectors or draft ISO 80369-6 'non-Luer' connectors. The procedures included spinal anaesthesia; intrathecal chemotherapy; lumbar puncture, cerebrospinal fluid collection and pressure measurement; epidural catheter placement with bolus injection and critical care use. Participants attempted cross connection between neuraxial connectors and a range of other medical device connectors, including those from the ISO 80369 small-bore connector series. Video recording analysis was used for all assessments. Participants subjectively assessed performance of the draft non-Luer connector, including suitability for routine clinical use. Participants performed 198 procedures. The connector achieved easy, leak-free connections. The willingness of participants to use the non-Luer connectors were: spinal anaesthesia 100%; intrathecal chemotherapy 88%; lumbar puncture, cerebrospinal fluid collection and pressure measurement 93%; epidural catheter placement with bolus injection 78%; critical care use 100%. Concerns raised were generally device related, rather than connector related. Most cross-connection attempts failed, even using above clinical forces and, when successful, were judged of low clinical risk potential; the exception was a malaligned connection between the non-Luer slip and female Luer connectors. This led to revision of the dimensional tolerances of the non-Luer connector to reduce this risk, before publication of the final specification in 2016. We conclude that the ISO 80369-6 neuraxial non-Luer connector is suitable for clinical use. [ABSTRACT FROM AUTHOR]

Offering rapid HIV testing improves rates of testing in adults, but little is known about whether offering adolescents a choice of testing methods increases rates of testing. The aims of the study were to determine rates of HIV testing in adolescents when different testing methods were offered and explore factors associated with agreement to be tested for HIV. Participants (n = 200, sexually experienced 13-22 year olds) were recruited from an urban adolescent clinic, completed a 99-item theory-based survey and were offered their choice of venipuncture, rapid fingerstick or rapid oral fluid HIV testing. Approximately half (49.5%) agreed to HIV testing. Male gender, parental completion of high school, intention to test for HIV if offered by clinician and higher perceived likelihood of current HIV infection were independently associated with agreement to test. Combining new strategies, such as opt-out testing, with routine testing may be needed to improve rates of adolescent HIV testing. [ABSTRACT FROM AUTHOR]

The Driver Behaviour Questionnaire (DBQ) has mainly been used as a predictor of self-reported road traffic accidents. The associations between crashes and the violation and error factors of the DBQ, however, may be spuriously high due to reporting bias. In the present study, the DBQ was tested as a predictor of self-reported and recorded accidents in four samples of private and professional drivers. The findings show that the DBQ scale only predicts self-reported accidents, not recorded crashes, despite the higher validity of company data and the higher means of the recorded data across these samples. The results can be explained by a common method variance bias. In a review of the DBQ research, the use of the instrument was found to be heterogeneous concerning the number of items, scales used and factor analytic methods applied. Thus, the DBQ may not be as homogeneous and as successful in predicting accidents as is often claimed. [ABSTRACT FROM AUTHOR]

One of the assumptions of the theory of accident proneness is that drivers' accident liability is stable over time, which was tested in the present paper. Previous investigations of this problem (or rather the conclusions) were found to be deficient because they did not take into account the statistical problem of low variance in the accident variable. However, by correlating the between time periods association coefficient and the mean number of accidents across several samples, this problem can be overcome. Therefore, the stability of accident record over time was investigated in five samples of British bus drivers. It was found that the size of the correlations between time periods increased with the increase in mean accident frequency. Furthermore, this increase could be described by a linear regression line, which fit the various points extremely well. Also, the size of correlations of 'at fault' accidents increased faster with the mean than did 'all accidents', although the latter had a higher initial value. It was therefore concluded, in contrast to previous authors, that the accident record of drivers is quite stable over time and that the very low correlations that have often been found were due to the samples and methods used (low-risk drivers and short time periods equalling low crash means) and not of any inherent instability in drivers' behaviour and/or accident record. It was also concluded that only culpable accidents should be used for this type of calculation. No evidence was found for a decrease in correlation size between single years' accidents when time periods between the years were lengthened, i.e. accidents in one year predicted accidents in several other years equally well. However, the period used was rather short. The results are discussed with reference to training intervention for accident-involved drivers, especially for organisations with major fleets, such as bus companies. [ABSTRACT FROM AUTHOR]

In numerical modelling of the resistance spot welding process, a significant input parameter is the value of the weld current and traditionally, the rms value corresponding to the actual, instantaneous current waveform is used. The rms value implies a constant weld current for the entire weld time instead of the real-time current waveforms. Although the rms value represents an effective approximation of the real-time current waveform, the influence of the peak current and of the current slopes in each half cycle on the welding process cannot be realised in modelling when the rms value is used. Mathematically, an alternating current waveform with higher peak value and lower current on-time in each half cycle may correspond to a rms value that is nearly similar corresponding to another waveform with lower peak value and larger current on-time in each half cycle. The resulting rate of heating and the subsequent size of the weld nugget may not be the same for both the current signals since the resistive heating in resistance spot welding is transient in nature. This is precisely observed in the present work through a detailed investigation using three different ac spot welding machines. A two-dimensional, axisymmetric model is used to analyse the spot welding process using both the actual current waveform and the corresponding rms value as inputs. The computed weld dimensions show better predictions with the instantaneous current waveform as input rather than the corresponding rms value. [ABSTRACT FROM AUTHOR]

Effects of stress on driving performance can depend on the nature of driver's stress reactions and on the traffic environment. In an experimental study, we assessed multiple dimensions of vulnerability to driver stress by a questionnaire that was validated in previous field studies and related those dimensions to performance on a driving simulator. Results were broadly consistent with prediction. A dimension of habitual dislike of driving was associated with reduced control skills, greater caution, and disturbance of moods. A measure of aggressive driving predicted more frequent and more error-prone overtaking, which are effects attributed to the use of confrontive coping strategies in interaction with other vehicles. An alertness measure predicted speed of reaction to pedestrian hazards. This research has practical applications for system design, automated monitoring of driver performance, selection and assessment of drivers, and training. [ABSTRACT FROM AUTHOR]

The Driving Behaviour Inventory (DBI), developed as a measure of dimensions of driver stress, was completed by 61 participants on two occasions separated by an interval of 5 months. Coefficients alpha, test-retest realiability, and correlational analyses between the five scales derived from earlier factor analyses revealed that the ‘driving aggression’, ‘dislike of driving’, ‘irritation when overtaken’ and ‘frustration in overtaking’ scales were reliable. The ‘general driver stress’ scale, derived from the single factor solution, was found to be particularly robust. In its original form the ‘driving alertness’ scale was found to be less robust. Minor changes in respect of adding items to and deleting items from three of the scales improved their reliability. It is concluded that overall the DBI is a reliable self-report measure of driver stress. [ABSTRACT FROM PUBLISHER]