Aleksandar Zunjic

Anthropometric assessment of crane cabins and recommendations for design: A case study

BACKGROUND Work of crane operators is very difficult and demanding. Therefore, it is very important that the cabin of a crane be designed on the basis of relevant anthropometric data. However, it is very difficult to find a research that considers anthropometric convenience of crane cabins. OBJECTIVE From the theoretical viewpoint, it is important to perceive and to classify effects of the anthropometric incompatibility of crane cabins. Globally, the objective is to consider the anthropometric convenience of existing crane cabins, and possibilities for improvements of their design from the ergonomic point of view. In this regard, it is significant to detect constraints that impede or hinder the work of the crane operators, which could be overcome with certain anthropometric solutions. The main objective is to examine whether and to what extent is justifiable to use anthropometric data that are obtained on the basis of general (national) population, during designing the crane cabins. METHODS For the assessment of existing crane cabins and the work of operators, four methods were used: observation of the work of the operators and design solutions of the cabins, the checklist approach, interviewing of operators and the experimental research based on obtaining the data on the population of crane operators. RESULTS Results of the analysis based on the method of observation, analysis based on the application of the checklist, as well as interviewing of the operators indicate that certain construction constraints of the components in the cabins are the main reasons of reduced visibility and improper working postures of operators. All this has caused the emergence of continuous musculoskeletal loading of the crane operators. The results of the anthropometric research that were obtained on the population of crane operators in this case study suggest that there is a statistically significant difference, when compared data of this population of workers with anthropometric data from the general population. CONCLUSIONS Analyzed workplaces in crane cabins do not correspond to the majority of operators from the anthropometric standpoint. The conducted anthropometric analysis has been indicated that could be made the mistake, if dimensions of the cabin and layout of equipment would be relied on data derived from the general population of citizens. In order to achieve greater precision in the design and configuration of equipment, it is recommended using the data that are obtained directly on the population of the crane operators when designing the cabin.

Fuzzy Multicriteria ABC Supplier Classification in Global Supply Chain

The determination of the optimal purchasing strategy in enterprise that is a part of global supply chain could be performed in two steps. In step one, a classification of potential suppliers is performed in order to determine the optimal portfolio of suppliers. This is delivered by using the fuzzy multicriteria proposed ABC classification method. Uncertainties in relative importance of criteria and their values are described by linguistic expressions. Modelling of linguistic expressions is based on the fuzzy sets theory. In the second step, ranking of optimal portfolio of suppliers is performed by using the modified ELECTRE method. The obtained results represent valuable input for determining the long time purchasing strategy and building partnership with the best suppliers. The developed two-step model is verified on real life data. The obtained results indicate good compliance with the opinions management in this type of industry. It is worth to mention that the proposed model can be easily extended and adopted to the analysis of other issues of management which could be applicable in different research areas.

Research of injuries of passengers in city buses as a consequence of non-collision effects

In this study, a research of injuries of passengers in city buses is presented, which are not a consequence of collision of buses with other objects. The number of injured passengers in the territory of Belgrade was registered, during three consecutive years. Most frequently injured body part was the head, while women over the age of 60 are the most vulnerable population of passengers. The most often reason for the appearance of injuries was the effect of acceleration. Also, it is pointed out to the importance of consideration of the problem of multiple injuries. These injuries are more complex than the individual ones, and they may indicate to the existence of greater omissions in the design of the interior of the bus. Proposals for certain system solutions, as well as some recommendations for designing are given, which can improve the safety of passengers who use the city bus as a means of transportation.

Development and Application of a Decision Support System for Human Reliability Assessment – A Case Study of an Electric Power Company

This paper describes the human reliability assessment using absolute probability judgment (APJ) method in the Electric Power Company of Serbia (EPS). Taking into account conventional APJ approach, a new decision support tool EPS-APJ was developed. The EPS-APJ tool is intended for use by a group of experts for human error probability assessment. The basic goal of the tool is to facilitate the process of decision-making by experts, in the complex environment of the electric power companies. The usefulness of this new tool is approved in a case study of use of the EPS-APJ for the purpose of the analysis of a repair intervention on a 10/0.4-kV steel lattice tower ‘Nogaje’, in the EPS. For the purpose of this study, a database on work-related injuries, accidents, and critical interventions occurred over a 10-year period was created. The research comprised analysis of 1074 workplaces, with the total of 3997 employees. The case study performed at the EPS has confirmed that the EPS-APJ tool for quantification of human errors is highly applicable, comprehensive, and simple to use. Comparison of the results obtained by application of the EPS-APJ tool versus the basic APJ method has confirmed the accuracy of the decision support tool, and significant speed advantage in conducting an expert evaluation. Copyright

Effects of screen filter on visibility of alphanumeric presentation on CRT and LCD monitors.

In this paper, a research that deals with the problem of determining of the visibility of the alphanumeric presentation on CRT and LCD screens is presented, in conditions when the screen filters are used, and when they are not used. A methodology that can be used for determination of the visibility of alphanumeric symbols on VDT screens is presented. It is determined the existence of differences in visibility of alphanumeric presentations when screen filters are used, compared to conditions when they are not used. This difference was statistically significant, while the visibility of the presented alphanumeric symbols on CRT and LCD screens that use screen filters is lower than when they are not used. For this reason, the use of protective screen filter is recommended in circumstances where a very high level of glare exists, when the visual fatigue is common appearance and when a user performs a task that does not depend on the detection of stimuli whose RGB values are low.

Universal equation for the relative change in profit of manufacturing company

In contemporary conditions of the companys business operations, where high dynamics of costs, sales volume and change of production programme is present, it is of crucial importance to investigate their effects on the change of profit. Starting from cost–volume–profit equation, the aim is to arrive at a universal equation that will simultaneously measure a relative change in profit for a number of products, not only under the influence of change in sales volume but also of other relevant variables, such as sales price, fixed and variable costs. The basic hypothesis is that it is possible to establish in a form of universal equation the dependence between the change in profit and change in influential variables. In this investigation, first it was observed the partial influence of some variables on the change in profit and their dependence was determined for a single product, and then for more than one product. Finally, by summing up all those effects, a universal equation of profit change was obtained. The derived universal equation for the relative change in profit along with simultaneous effects of several variables makes possible for the company management to more simply determine the profit for diverse conditions of business operations. The universal equation for the relative change in profit was applied in one company and the results obtained confirm its significance.

Identification of invariant factors that determine labour output on the production line

Abstract The efficiency of the production line system has been investigated by gaining a complex insight into a large number of variables affecting its functioning. The basic hypothesis of this paper concerns the existence of invariant factors that determine labour output on the production line. Applying factor analysis to constructed databases, the factors are extracted that confirm the basic hypothesis of this paper. In this research, multivariant analysis has been applied: cluster analysis to display the validity of ramification of the primary sample to small subgroups and factor analysis has been applied to the primary sample and the subgroups. The results of the application of the software package SPSS (Statistical Package for the Social Science) show that there are stable invariant factors that determine labour output on the production line. Invariant factors that determine labour output on the production line include: motivation of workers for production line work; elimination of adverse effects of work on the production line; rhythm of work; and psychophysical fatigue. The identified invariant factors provide a deeper insight into labour output as well as enabling the planning of activities that can improve production line work and make it more efficient.

SCANAM method for the assessment of industrial noise

Work in an industrial environment is often associated with high levels of noise. For measuring and evaluating of noise levels, sometimes it is necessary to use several instruments. These instruments can be very expensive and require qualified personnel. Medium and small-sized firms often lack sufficient financial resources to ensure continuous measurement and assessment of noise levels. For this reason, a new SCANAM method for assessing the levels of noise is designed. This method involves the use of cheap and accurate sound level meter and specially designed software for assessing the effects of noise. Application of this method is very simple. Based on a noise sample in duration of eight hours, the accuracy of the SCANAM method was confirmed. Application of this method is significantly cheaper than an approach based on the use of expensive multi-function devices, or separate devices for measuring and assessing noise at the workplace.

Readability as a Component of the Usability of a Web Presentation - A Case Study from the Banking Sector

In many comprehensive and overall considerations of usability of web presentations, readability as a factor that potentially influences usability is not represented at all, or it is represented unsystematically and superficially. The main goal of this paper is establishing a connection between usability and readability. There is no known research that previously dealt with this topic. In order to establish the above correlation, firstly the classification of usability features was performed. This original classification has had an important function in identifying the major website usability constructs. Based on the identified major usability and readability features (constructs), an original questionnaire for assessing the usability and quality of websites was formed. This tool, together with the interviewing method was used in the case study, which referred to the website of a company operating in the banking sector. As a result of the case study, a high correlation of 0.943 is established between the organization of information on the screen (a usability feature) and the structure of headings, sub-headings, and positioning of the text (a readability feature). The existence of a strong link between the possibilities for finding information (a usability feature) and the content (explanations, arguments, coherence) of the textual presentation (a readability feature) has been established. This and other results obtained indicate that complex considerations that refer to the usability of websites, as well as tools that are used for usability assessment should involve in a systematic way the readability as an important factor, which can have the influence on usability.