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Introduction
Published in Joseph Y.-T. Leung, Handbook of SCHEDULING, 2004
In the online weighted flow time problem, each job Ji has an associated positive weight wi that is revealed to the clairvoyant scheduler at the release time of Ji. The objective function is ∑wiFi. If all wi=1 then the objective function is total flow time, and if all wi=1/pi then the objective function is total stretch. Some systems, such as the Unix operating system, allows different processes to have different priorities. In Unix, users can use the nice command to set the priority of their jobs. Weights provide a way that a system might implement priorities. For the moment let us focus on one machine.
From Parking Meters to Vending Machines: A Study of Usability Issues in Self-Service Technologies
Published in International Journal of Human–Computer Interaction, 2023
Hamish Henderson, Kazjon Grace, Natalia Gulbransen-Diaz, Brittany Klaassens, Tuck Wah Leong, Martin Tomitsch
The proximity of the input/output devices to one another played an important part in the participants’ perception of cohesiveness (“It would have been nice to integrate the eftpos in the screen rather than a separate system. Just to make it flow better.”—P16). The further apart the input/output devices were from each other, the more difficulty the participant had in seeing the relationship between them. As many of the SSTs are physically bigger than the user, the space between devices could be material. When participants were focussed on a particular input/output device, they often failed to recognise another input/output device necessary to complete their task as it was outside of their immediate field of view (“What is interesting is that when the card was declined, this machine over here made a sound and went red. I didn’t even notice its existence. More integration there is probably needed.”—P15). Participants occasionally had to step back and visually scan the SST to bring all elements into their field of view.
Stability assessment with the stability index
Published in Quality Engineering, 2019
Willis A. Jensen, John Szarka, Kevin White
In our review of the literature, we did not find a consensus regarding the best way to assess process stability with metrics. There are a variety of methods that have been proposed, which we describe here. We have argued for the use of the SI in lieu of other stability metrics. The SI has advantages in ease of calculation, interpretability, applicability, and connection to capability, while still providing good statistical performance. It is our hope that the SI will be more commonly used by quality practitioners in conjunction with the popular capability indices, particularly for situations with many process variables to monitor. The process performance graph shown in Figure 10 is a nice way to summarize many process outputs to prioritize capability and stability improvement opportunities. We believe that industry has focused too much on capability at the expense of process stability and encourage practitioners to take a more holistic view and assess stability and capability together to improve quality.