Does a rolling floor reduce the physical work demands and workload, and increase the productivity of truck drivers handling packed goods?

A PCM rolling floor (RF) was developed to reduce the risk of musculoskeletal complaints among truck drivers. The RF can be used to move packed goods automatically in and out of the cargo space. The efficacy of this intervention on physical work demands, energetic and perceived workload and productivity was evaluated by comparing nine truck drivers working with a RF and a traditional, non-moving floor during a working day. Since the RF was not used during the loading process, no effects were found. The RF reduced the unloading process by 8 min, decreased the frequency of lifting and setting down goods by 24%, decreased the frequency of handling goods below knee level by 79%, and decreased the frequency of entering the cargo space by 45%. No effect was found on the energetic and perceived workload. The RF resulted in a small increase in productivity.     

Handwriting recognition or reading? What is the situation at the dawn of the 3rd millenium?

During the last forty years, Human Handwriting Processing (HHP) has most often been investigated under the frameworks of character (OCR) and pattern recognition. In recent years considerable progress has been made, and to date HHP can be viewed much more as an automatic Handwriting Reading (HR) task for the machine. In this paper we propose the use of handwriting invariants, a physical model for a first segmentation, a logical model for segmentation and recognition, a fundamental equation of handwriting, and to integrate several sources of perception and of knowledge in order to design Handwriting Reading Systems (HRS), which would be more universal systems than is currently the case. At the dawn of the 3rd millennium, we guess that HHP will be considered more as a perceptual and interpretation task requiring knowledge gained from studies on human language. This paper gives some guidelines and presents examples to design systems able to perceive and interpret, i.e., read, handwriting automatically. Received October 30, 1998 / Revised January 30, 1999     

When is an information infrastructure? Investigating the emergence of public sector information infrastructures

Drawing on the notion of information infrastructure as a relational concept, this paper endeavours to highlight the links between data standards and institutional facts. Although social science studies have emphasised the interplay between socio-technical factors, the author suggests that such approaches have overlooked the role that institutional facts play in the development of information infrastructures. An in-depth, qualitative case study of a recent episode of institutional change within the criminal justice system of England and Wales reveals how institutional facts are entangled with data standards through iterative sets of constitutive rules that are mirrored by their associated logical messages in an isomorphic fashion.     

When is the discretization of a spatially distributed system good enough for control?

This paper describes a new and straightforward method for controlling spatially distributed plants based on low-order models obtained from spatial discretization techniques. A suitable level of discretization is determined by computing the sequence of ν-gaps between weighted models of successively finer spatial resolution, and bounding this by another sequence with an analytic series. It is proved that such a series forms an upper bound on the ν-gap between a weighted model in the initial sequence and the spatially distributed weighted plant. This enables the synthesis, on low-order models, of robust controllers that are guaranteed to stabilize the actual plant, a feature not shared by most model reduction methods where the gap between the high-order model and plant is often not known, and where the gap between high-order and reduced models may be too expensive to compute. Since the calculation of the current bound is based on weighted models of small state-dimension, the new method avoids the numerical problems inherent in large-scale model reduction based approaches. The ideas presented in this paper are demonstrated on a disturbance rejection problem for a 1D heat equation.     

Investigating the validity of subjective workload rating (NASA TLX) and subjective situation awareness rating (SART) for cognitively complex human–machine work

Subjective workload and situation awareness measures, such as the NASA task load index (TLX) and the situational awareness rating technique (SART), are frequently used in human–system evaluation. However, the interpretation of these ratings is debated. In this study, empirical evidence for the measures' theoretical assumptions was investigated by comparing operators' ratings collected immediately after performing a scenario and ratings collected after operators' acquisition through a video review of the scenario, knowledge of actual system states. Eighteen licensed control room operators participated in the simulator study, running 12 relatively challenging scenarios. It was found that the interpretation of TLX items involving introspection remained stable after operators acquired factual scenario knowledge, while the interpretation of items involving the perception of external events, such as situation awareness and performance, depended on the operators' scenario knowledge. The result shows that operators’ ratings could discriminate between mental effort, performance, frustration, and situation awareness. No clear evidence for the SART index as a measure of situation awareness was found. Instead, a subjective situation awareness measure developed for this study was distinct from workload and related to operator performance, showing that this type of measure warrants future investigation of its validity. The study findings help in developing measurement procedures and interpreting subjective measures. Finally, the study reveals that informing operators about the scenario can provide useful subjective ratings of situation awareness and performance. Future research should include procedures for how to inform participants adequately and efficiently in subjective assessments.     

Exploring the positive side of personal internet use at work: Does it help in managing the border between work and nonwork?

Many employees use the internet at work for personal reasons, and it has been suggested that this behavior can be understood as an attempt to manage the border between work and nonwork. Using data from 190 office workers, the study aims to test how well work/family border theory can explain personal internet use. The results only partly support work/family border theory, as only the amount of private demands and identification with work at work were significant predictors of personal internet use (which was found to be unrelated to work–nonwork balance). These findings suggest that work/family border theory offers only a limited perspective for the explanation of why people use the internet at work for personal business.     

Do we want to keep working in 12-h shifts? The follow-up of the work schedule change in a Portuguese industrial company

BackgroundIn Europe, atypical work schedules assume an increasing position, framed by the so-called “adaptability regime”. Despite being seen as a “temporary” option, this regime supports the extension of the working hours up to 12 h per shift.ObjectiveThe purpose of this study was to analyse how the workers from a Portuguese industrial company perceive the impacts of a 12-h schedule, after replacing the former 8-h shift schedule.MethodsThe sample included a total of 87 shiftworkers of an industrial company. A mixed method research was followed based on the ergonomic work analysis, using observations; a self-report instrument describing a week working on 2 × 12 h; and a questionnaire.ResultsField study findings are consistent in showing that, in 2 × 12 h, the workers perceive the risks as resized, both physical risk factors (e.g., noise) and factors related to the work organization (e.g., work pace). The results also reveal a perceived aggravation of the main health outcomes: “sleep debt”, feeling of chronic fatigue, and muscles pains. Despite this, most workers prefer the new 12-h schedule, but not until their retirement age.ConclusionAt present, it is noticed that the new schedule receives collective acceptance and is considered the least-worst option; the advantages outside work seem to compensate the higher costs imposed by this schedule.Relevance to industryOur findings highlight ergonomics' contribution to the sustainability of the work in 12-h shifts, establishing the conditions that enable a technical-scientific opinion supporting the company's decision on the exposure length of the workers to these work schedules.     

When is it reasonable to implement the discontinuous sliding‐mode controllers instead of the continuous ones? Frequency domain criteria

Professor Utkin proposed an example showing that the amplitude of chattering caused by the presence of parasitic dynamics (stable actuators) in some systems governed by the First‐Order Sliding‐Mode Controller is lower than that produced by the Super‐Twisting Algorithm. This example served to motivate this paper reconsidering the problem of comparison of chattering in systems with stable actuators, and driven by Discontinuous Sliding‐Mode Controllers (DSMCs) and Continuous Sliding‐Mode Controllers (CSMCs). Comparison of chattering produced by DSMC and CSMC taking into account their amplitudes, frequencies, and average power (AP) needed to maintain the system into real‐sliding modes, allowing to conclude the following: (i) for systems with slow actuators, the amplitude of oscillations and AP produced by DSMC be smaller than those caused by CSMC; (ii) for bounded disturbances with fixed Lipschitz constant, there exist sufficiently fast actuators for which the amplitude of oscillations and AP produced by CSMC be smaller than those caused by DSMC.     

“… or is the question of being at once the most basic and the most concrete?” On the ambitions and responsibilities of contemporary American philosophy

At its centennial in 2001, the American Philosophical Association bravely proclaimed: “Philosophy Matters.” But does it? It won’t unless it reaches the concreteness of everyday life. To do so was Martin Heidegger’s ambition, and one can read Saul Kripke’s books as an attempt to get mainstream American philosophy beyond its abstractions. At length, Kripke’s efforts, on one reading, failed while Heidegger’s remained incomplete. A theory of commodification can get us closer to the things that matter to us in everyday life.