Equivalence of disturbance observer structures for linear systems

Several techniques exist to incorporate disturbance rejection requirements in a linear controller design. Contrary to, for example the H-infinity controller design technique where only one degree of freedom is available to obtain both disturbance rejection and performance, a disturbance observer adds a degree of freedom, thereby enabling a separate design of the disturbance rejection and the performance. There are many ways to design, implement and represent disturbance observers. We focus on two design methodologies and their corresponding representations. It can be shown that, in the case that the (SISO) plant is linear, the methodologies result in an equivalent disturbance observer. We use this equivalence to relate some properties well-known for one methodology to the other methodology, and vice vers

Loss of labor time due to malfunctioning ICTs and ICT skill insufficiencies

Purpose – The purpose of this paper is to unexplore the area of information and communication technology (ICT) use in organizations related to the assumed productivity gains by the use of ICTs. On the one hand, the paper focus on the losses of labor time that are caused by malfunctioning hardware or non-functional software, and on the other hand, the paper focus on the labor time losses that are caused by a lack of skills to maximize ICT. Design/methodology/approach – To estimate these losses, the paper conducted a large-scale survey among the Dutch workforce. The respondents were presented scenarios, and then they were asked to assess the loss of labor time. Findings – When working with ICTs, malfunctioning ICT and ICT skill insufficiencies lead to a loss in labor time of 7.5 percent. The losses increase with decreasing educational attainment level. Age does not contribute to the total average losses. Workers highly underestimate the effects of ICT-related training. The role of co-workers is more significant than the formally organized means by the organization. Originality/value – Due to ICT's significance among the labor force, investigating the reported losses is an important step to further improve the use of ICTs in the workplac