Reliability and maintainability assessment factors for reliable fault-tolerant systems

A long term goal of the NASA Langley Research Center is the development of a reliability assessment methodology of sufficient power to enable the credible comparison of the stochastic attributes of one ultrareliable system design against others. This methodology, developed over a 10 year period, is a combined analytic and simulative technique. An analytic component is the Computer Aided Reliability Estimation capability, third generation, or simply CARE III. A simulative component is the Gate Logic Software Simulator capability, or GLOSS. The numerous factors that potentially have a degrading effect on system reliability and the ways in which these factors that are peculiar to highly reliable fault tolerant systems are accounted for in credible reliability assessments. Also presented are the modeling difficulties that result from their inclusion and the ways in which CARE III and GLOSS mitigate the intractability of the heretofore unworkable mathematics

Social Transparency in Enterprise Information Systems: Peculiarities and Assessment Factors

Social transparency within an organisation refers to the intentional sharing by individuals of information relating to themselves and their group to others in the workplace. This includes announcingpersonal interests, activity status, prioritiesandpersonal achievements. Such transparency is typically intendedto increase relatedness, motivation and trust amongst colleagues.Social networking features are being embedded within organisational information systems,allowing an online version of social transparency.An ad-hoc implementation of such transparency can poseissues such as information overload, motivating unwantedgrouping amongst colleagues and increasingpressureto perform in a certain manner. This results in organisational problems such asreduced productivity, unproductive competition and high turnover rates. Our ultimate aim isto address these issues by proposing an assessmentmethod for online social transparency to detect and minimise its negative impact on employees and organisations. In this paper, we report on empirical study results and present (1) a set of peculiarities of implementing online transparency in enterprise information systems and (2) a set of essential factors that relate to the assessment process

Impact of traffic noise on railway traffic safety

Traffic noise is one of the dominant factors of ergo-assessment. The harmful impact of traffic noise on the engine driver as target group can be studied in isolation from other ergo-assessment factors only in the initial phase of research. The simultaneous action of several related factors in the system of ergo-assessment factors has cumulative effect on the perception and psychomotoric status of the railway traffic participants in the appropriate traffic situation. The initial partial research of traffic noise by a combination of several scientific methods needs to be eventually upgraded by studying the relations among several concurrent important or dominant ergo-assessment factors

Satellite Power System (SPS) environmental impacts, preliminary assessment

Present power plant assessment factors are used to present satellite power system (SPS) impacts. In contrast to oil, gas, nuclear and coal fueled power plants, the SPS and hydroelectric power plants produce air, water, and solid waste emissions only during the construction phase. Land use impacts result from the placement of rectennas used for microwave receiving and rectifying. Air quality impacts of the SPS resulting from the construction phase amount to 0.405 metric tons per megawatt year. Solid wastes impacts are 0.108 metric tons per year of operation. Other impacts such as those caused by heavy lift launch vehicle sites are also discussed

What influences chronic pain management? A best–worst scaling experiment with final year medical students and general practitioners

Background: Chronic pain education is an essential determinant for optimal chronic pain management. Given that attitudes and preferences are involved in making treatment decisions, identifying which factors are most influential to final year medical students’ and general practitioners’ (GPs) chronic pain management choices is of importance. This study investigates Swedish and Australian students’ preferences with respect to a chronic pain condition, using a best–worst scaling (BWS) experiment, which is designed to rank alternatives. Methods: BWS, a stated-preference method grounded in random utility theory, was used to explore the importance of factors influencing chronic pain management. Results: All three cohorts considered the patients’ pain description and previous treatment experience as the most important factors in making treatment decisions, whereas their demographics and voices or facial expressions while describing their pain were considered least important. Factors such as social support, patient preferences and treatment adherence were, however, disregarded by all cohorts in favour of pain assessment factors such as pain ratings, description and history. Swedish medical students and GPs show very high correlation in their choices, although the GPs consider their professional experience as more important compared to the students. Conclusion: This study suggests that the relative importance of treatment factors is cemented early and thus underline the critical importance of improving pain curricula during undergraduate medical education

Improved scientific basis for human health risk assessment factors by toxicokinetic population modeling

Exposure limits or guidelines are derived to protect humans from adverse effects caused by exposure to chemical substances in the environment or at the workplace. The internal dose of a chemical is determined by toxicokinetic (TK) processes such as uptake, distribution and elimination, and is closely related to the risk of adversity. The internal dose varies among individuals due to differences in age, genetics, physical activity, health status and life-style. Thus, it is important to address population variability for the exposure limits to be protective. TK variability is typically accounted for by the use of a default assessment factor of 3.16. However, the scientific basis of the exposure limits may be improved by replacing the default value with a chemical specific adjustment factor (CSAFHK), derived from experimental data. By doing so, more appropriate exposure limits are achieved, and large costs for society associated with both too high and too low exposure limits may be avoided. Substitution of the default value is often obstructed by the lack of suitable experimental data. In this thesis, this limitation was addressed by the development of a probabilistic framework using physiologically based pharmacokinetic (PBPK) modeling. It was used to derive CSAFHK for four commonly used organic solvents; acetone, toluene, styrene and methyl chloride. PBPK models based on information on anatomical, physiological and biochemical parameters were used to calculate the internal doses following inhalation exposure to the four chemicals. A description of washin-washout in the respiratory tract was evolved for polar solvents such as acetone. Additional information on the model parameters contained in human experimental toxicokinetic data was taken advantage of by Bayesian analysis. Meanwhile, the methodology was explored with respect to prior assumptions. CSAFHK were derived from population distributions of internal dose obtained by Monte Carlo (MC) simulation from distributions of the model parameters. The influence of age and gender on the internal dose was slight. Thus, the factors obtained for all substances were below 2.5. However, the effects of fluctuations in exposure level and workload increased the CSAFHK up to 6.1, indicating that workplace exposure may need specific attention. Given the diverse properties of acetone, toluene, styrene and methyl chloride, the results can probably be generalized to most organic solvents and similar chemicals. The CSAFHK presented in this thesis are derived from extensive information on intraspecies toxicokinetic differences and cover the effects of common toxicokinetic modifiers. Thus, they are well suited to replace the default value. The population framework may be further extended to include other chemicals, as well as additional experimental data on population variability when such becomes available

From pass to pass with distinction+

The present essay addresses the issue of equivalent grading and assessment of pupils’ written production. The main question was how teachers assess and grade pupils’ essays. Three essays written by pupils in year nine were assessed and graded by four different teachers; the grades awarded varied from Pass to Pass with distinction+. The teachers’ assessments as well as the pupils’ essays were analysed and discussed in relation to the syllabus for English and the assessment guidelines accompanying the national tests. It was shown that teachers generally base their assessment on the syllabus and/or on the assessment guidelines accompanying the national tests. However, the differences found in the assessment and grading of the texts could be explained by the fact that the teachers stressed different assessment factors, i.e. they considered some assessment factors and/or some goals to be more important than others. For instance, some of the teachers emphasised formal correctness while others stressed the importance of a comprehensible content