Capacity model keele pdf

They will be the bottlenecks for the next X days or weeks. When we know that we can increase shifts on those tools, we can add more manpower if it can help, and reduce setup times.

So we can increase the amount of ice cream produced by using our resources where they are most needed. Another capacity model is the dynamic model which allows us to change the demand and number of tools each period of time.

I will not explain this model in this post. I will walk you step by step through the process of building a simple capacity model. You can then download the model from the following Capacity model link. Tool list — tool name, availability of each tool, and tool units per hour UPH based on past data. Units per hour UPH — we will use the average unit per hour that the tool can produce.

In an improved model we will use units per hour per product. We can just increase availability. Products vs. In a more complex model, a product will be able to run on more than 1 tool. The list should look like this:. Time buckets — a term used to describe periods of time that we look at as a block of time.

Example : if we use week as a time bucket in the model, we will take the whole week as a time bucket and not look at each day separately. Before going to the next list we will need to decide which time buckets we want to use. Weeks or months are standard. In the capacity model, we can look at different time periods in parallel.

That way we can look at short-term and mid-term. We can use as many time buckets as we want. We just need to remember that if the time bucket is too small, we will get bad data since we are using averages and average almost never happens in the real world. Calculate the time needed for production for each tool for every time bucket. We will do it in 2 steps:. A tool with a UPH units per hour of should produce units of product A and units of product B.

Together they will need 14 hours on the tool. We can see that the loading on the tools is not balanced. What is the purpose of the model? We want to look for the tools that will have a loading problem and see how we can ease the loading on them.

You can increase the margin as you wish. If we can find a product that runs on a different tool that is not loaded, we will change the main tool of this product to be the not loaded tool. As mentioned before, we must do that not only in the model but also in real production planning.

If option 1 is not possible, c alculate the desired availability for the overloaded tool. The factory can put extra attention on tool 2. The maintenance will respond faster, they will reschedule unnecessary preventive maintenance.

We might add more personnel for the setup phase to do it faster. There are plenty of things we can do to increase availability for a specific period of time, but we need to know what number we need to aspire to. That number is the output of the capacity model. Dealing with the demand side — when options 1 and 2 are not available, we will need to work with the salespeople, firstly by notifying them about the products that might not be available, secondly if we have good synergy between the sales and the production, they can help with the following:.

If a customer ordered , units, is it OK if he gets 30, units every week for 4 weeks? Attention is defined as the mental process of concentrating effort on a stimulus or mental event: the limited mental energy or resource that powers the mental system. Attention can also be defined as the cognitive process of selectively concentrating on one aspect of the environment while ignoring other things. Attention has also been referred to as the allocation of processing resources.

Examples include carefully listening to what someone is saying while ignoring other conversations in a room the cocktail effect or listening to a cell phone conversation while driving a car. It is the taking possession by the mind, in clear and vivid form, of one out of what seem several simultaneously possible objects or trains of thought.

Focalization, concentration of consciousness is of its essence. There are many theories of attention; among them are the Attenuation theory, Filter theory, Capacity model, Deutsch and Deutsch model, Multimode theory and the Schema theories of attention.

To begin I will tackle the Attenuation theory propounded by Anne Treisman. This theory also has some flaws and include that the theory does not explain exactly how semantic analysis works. Also the nature of the attenuation process has never been precisely specified. Donald Broadbent is recognized as one of the major contributors to the information processing approach, which started with his work with air traffic controllers during the war.

In that situation a number of competing messages from departing and incoming aircrafts are arriving continuously all requiring attention. Broadbent designed an experiment dichotic listening to investigate the processes involved in switching attention which are presumed to be going on internally in our heads. Broadbent argued that information from al the stimuli present at any time enters a sensory buffer. One of the inputs is then selected on the basis of its physical characteristics for further processing by being allowed to pass through a filter.

Since we have only a limited capacity to process information, this filter is designed to prevent the information processing system from being overloaded. The inputs not initially selected by the filter remain briefly in the sensory buffer, and if they are not processed they decay rapidly. Broadbent assumed that the filter rejected the non-shadowed or unattended message at an early stage of processing.

Also that analysis of the unattended message might occur below the level of conscious awareness. Thirdly is the Capacity model propounded by Kahneman.

This is a description of how demanding the processing of particular input might be. Some tasks might be relatively automatic in that they make few demands in terms of mental effort despite the fact that have a high information level, therefore Kahneman proposed that; some activities are more demanding and therefore require more mental effort than others, the total number available processing capacity may be increased or decreased by other factors such as arousal, also that several activities can be carried out at the same time provided that their total mental effort does not exceed the available capacity and finally that rules or strategies exist which determine allocation of resources to various activities and to various stages of processing.

Attention capacity will therefore reflect the demands made at the perceptual level, the level at which the input is interpreted or committed to memory and the response selection stage.

Critics have suggested that because of the ability to develop skills that it becomes impossible to accurately judge the limits or capacity of the processing system. Stephen Red in his book Cognition makes some summary comments on attention theories. Another of the attention theories is the Deutsch and Deutsch model.

The cocktail party effect influenced researches to look further than physical selection features, to semantic selection features. For example if you were at a social gathering having a conversation with some friends, when you hear someone mention your name and it grasps your attention.

This unattended-to- information somehow gained your awareness. This fueled development of the memory selection model which shares the same basic principles of early selection models that stimulus features are selected via their physical properties.

Attended and unattended information passes through the filter to a second stage of selection on the basis of semantic characteristics or message content.

Items which are selected are incorporated into short term memory and awareness. It tis the second selection mechanism rather than the filter that decides what information gains our awareness. An evaluation is that all stimulus, including those deemed irrelevant, are processed fully.

The next theory is the Multimode theory. The Multimode theory combines both physical and semantic inputs into one theory. Within this model attention is assumed to be flexible following different depths of perceptual analysis.

Switching from physical and semantic features as a basis for selection yields costs and benefits. Stimulus information will be attended to via an early selection through sensory analysis, then as it increases in complexity; semantic analysis is involved, compensating for attentions limited capacity.

Researchers found that semantic selection requires greater attention resources that physical selection. Stage 2 is the stage where semantic representations meanings are constructed and this corresponds to the Deutsch and Deutsch model of attention. The final stage is the stage where both sensory and semantic representations enter consciousness.