Transferring Tacit Knowldge in Process Control

Experienced operators, who have worked in process industry for many years possess extensive tacit knowledge regarding how to operate and control the plant. The purpose of this study was to propose methods for knowledge transfer regarding process control. Four conditions are important for successful knowledge transfer: resources from the management, access to a control room environment, access to saved process data from incidents and disturbances, and motivated experienced operators with verbal skills. Methods recommended for catching tacit knowledge regarding process control are observations in the control room, operators using the think-aloud methodology during work, and expert operators creating and analyzing scenarios of disturbances. Methods for transfer tacit knowledge are scenario analysis of disturbances in focus groups, or role-play between experienced and novice operator. Also informal and spontaneous methods for knowledge transfer can be successful

Chlorinated and brominated polycyclic aromatic hydrocarbons in ambient air: seasonal variation, profiles, potential sources, and size distribution

Chlorinated and brominated polycyclic aromatic hydrocarbons (ClPAHs and BrPAHs, respectively) are a new derivative group of PAHs. These halogenated PAHs (Halo-PAHs) have been reported to be carcinogenic and are considered emerging persistent organic pollutants. Gaining a clear understanding of the distribution and behavior of these ubiquitous organic pollutants is essential for the control and mitigation of their emission into the environment. However, research into the characteristics of Halo-PAHs in the atmosphere has been somewhat limited. This review paper thus aims to provide an overview of the seasonal patterns, profiles, potential sources, and particle-size distributions of atmospheric ClPAHs and BrPAHs with 3-5 rings. Most previous studies have focused on particulate Halo-PAHs and reported that their levels are higher during the cold season than during the warm season, with this seasonal variation more apparent for ClPAHs than for BrPAHs. In terms of their phase distribution, ClPAHs and BrPAHs share a similar trend, with their gaseous concentrations highest in summer and lowest in winter and their particulate concentrations exhibiting the opposite trend. Halo-PAH profiles have been shown to differ between sampling locations, possibly reflecting differences in the potential sources present at these sites, e.g., coal burning, traffic emissions, and industrial activity. The majority of Halo-PAHs tend to accumulate as ultrafine particles with an aerodynamic diameter of less than 1.0 mu m. Overall, a detailed understanding of the characteristics of Halo-PAHs in the atmosphere has yet to be achieved; hence, further research on atmospheric Halo-PAHs is necessary

Evaluation of RH Logic 400 office chair Influence on comfort, physical loads and performance during computer work

Today there is a large amount of knowledge about ergonomics and working sitting postures during long hours of office computer work. There is also a large selection of office chairs available on the market with numerous possibilities of individual adjustments for optimal and varied sitting postures. For the manufacturers it is of great interest to show advantages such as increased productivity, decreased discomfort and reduced physical disorders as well as improved health and well-being when their ergonomic chairs are used at work. For optimal usage it is important that the users take advantage of all the ergonomic features offered. However, often problems arise when a chair has a large amount of settings with various design and functionality. It is difficult without instructions and training to understand how the various settings work and how they should be handled and adjusted optimally for a specific individual. The purpose of this study was to examine if the possibilities that the RH Logic 400 office chair offers to create an ergonomic, individual and varied working posture were employed optimally by the users and also what effects the features had on comfort and work performance. The goal was to determine if positive effects regarding comfort, health and performance arise during 5 weeks of office computer work. Furthermore the goal was to find out how the RH chair and its adjustments were perceived and handled by the users when they were informed in different ways during introduction of the chair in their company. 84 office computer workers at two companies participated in the study during a period of five weeks. 48 of workers got the RH Logic 400 office chair, while the others kept their ordinary office chairs. These functioned as a control group. Among the RH chair users, 28 received an verbal introduction/training session of the chair’s functions from a manufacturer sales person together with a physiotherapist. The others only got access to a small written information brochure from the manufacturer hanging under the chair. Before the study all participants filled in a comprehensive questionnaire about their personal data, working situation and health status. Then they answered a questionnaire each week during a five weeks period about their health and well-being status as well as if the had adjusted their chair and used its features. Finally another comprehensive questionnaire was filled out when the test period was finished. In total 18000 data points were collected from 7 questionnaires (together including 82 questions with sub-questions). The data was statistically analysed using Wilcoxons signed-rank test and Student’s t-test. The significant level was set to 5%. The concluding results from the study showed that the RH Logic 400 chair significantly decreased the physical strain in the neck, shoulder and lumbar regions, and for the shoulders on the right hand side. People with previous long-term physical problems in the upper part of their body perceived decreased distress after five weeks work in the RH chair. The sitting posture and the comfort were perceived better for the RH chair than in the test subjects’ previous chair. They also felt more relaxed in the RH chair. However the chair and back cushions of the RH chair were perceived stiffer than in their previous chair. The RH office chair had a positive impact on the working situation as a whole, but did not affect the stress level at work. When discussing work performance and stress all parts in the working environment have an effect on well-being and it is therefore difficult to separate effects from the chair. The understanding about how the adjustments of the RH chair should be performed, as well as usage of the rocking function, increased significantly when verbal presentation and training were given, as well as how often the adjustments were used. However, when the users had found suitable settings, they did seldom adjust their chairs again during the test period. Sitting height was the measure that most often was adjusted while the positions of the neck rest and arm rests seldom were changed. The recommendation from this study is that when delivering office chairs to customers it is very important to introduce the users on how to adjust and handle the chair to accomplish optimal individual settings. Also point out that the chair should be adjusted several times a day and the rocking function should be used frequently to achieve necessary posture changes. Furthermore, explicit written information material need to be developed, explaining how good individual ergonomic working postures can be found by adjusting the chair’s different settings properly and also in which order the settings should be performed.

Microextraction by packed sorbent: an emerging, selective and high-throughput extraction technique in bioanalysis

Sample preparation is an important analytical step regarding the isolation and concentration of desired components from complex matrices and greatly influences their reliable and accurate analysis and data quality. It is the most labor-intensive and error-prone process in analytical methodology and, therefore, may influence the analytical performance of the target analytes quantification. Many conventional sample preparation methods are relatively complicated, involving time-consuming procedures and requiring large volumes of organic solvents. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation through extremely low volume or no solvent consumption. Micro-extraction techniques, such as micro-extraction by packed sorbent (MEPS), have these advantages over the traditional techniques. This paper gives an overview of MEPS technique, including the role of sample preparation in bioanalysis, the MEPS description namely MEPS formats (on- and off-line), sorbents, experimental and protocols, factors that affect the MEPS performance, and the major advantages and limitations of MEPS compared with other sample preparation techniques. We also summarize MEPS recent applications in bioanalysis.info:eu-repo/semantics/publishedVersio

On the Relation between Retention Indexes and the Interaction between the Solute and the Column in Gas-Liquid Chromatography

Gas-liquid chromatography retention indexes for organic molecules are determined by the interaction between the molecule and the column liquid phase. In this article, a model for calculating the interaction energy between a molecule and a dielectric wall is developed. The model is at least to our knowledge the first attempt to predict retention indexes from the interaction between the molecules and the column. This approach to predict retention indexes is radically different from methods proposed before. Earlier predictions of the retention indexes have been done by a large number of descriptors, which were linearly correlated to the retention indexes. The developed model has been tested for polycyclic aromatic hydrocarbons mainly with a molecular weight of 302. For the molecules with MW 302 the obtained correlation coefficient is 0.92. A somewhat simpler model is used to fit PAH with different MWs. A correlation coefficient of 0.998 is obtained if the retention indexes were fitted to the logarithm of the interaction energies between the PAHs and the column