Objectives and Constraints


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The screen shown below is the objectives and constraints screen in LOG 2.0. This screen is designed to give the user a brief overview of what is included in the model. This includes information on the planning horizon, constraints and the objective function used in the model.

Objective Function

LOG is designed to find the optimal solution to a model that maximises a particular objective or goal. LOG is able to either Maximise Net Present Value or Maximise Yield.

To select a particular objective simply click with the mouse on either Maximise Net Present Value or Maximise Yield.

Usually the objective will apply to all periods in the planning horizon but it is possible for the objective to only be calculated over a smaller period range. To maximise the objective over a smaller period range, click the box labelled ALL next to the selected objective so that the ‘tick’ disappears and then specify the first and last periods in the next two boxes.

By default LOG will choose to maximise net present value over all periods.

Number of Periods

Simply the number of years the model will run over.

Start Year

This is used in the reports generated by LOG and is the first year that the model runs for.

Discount Rate

The discount rate represents the opportunity cost of capital. If for example "5" was entered, this would represent a discount rate of 5%

End or Mid Year Discounting

Specify whether end or mid year discounting is used.

Regeneration Lag*

This specifies the replant lag that is currently incorporated into the model. The regeneration lag is the time difference between when a stand is cut and when it is replanted. This can be changed, but care should be taken. Changing the regeneration lag will change the data in the database, this process is moderately time consuming.

Other Changes to the LOG 2.0 Objectives and Constraints Screen*

Visually, the only change to the objectives and constraints screen is the inclusion of regeneration lag.

In LOG 1.01, the constraint summary did not work as intended. LOG would not save the constraints that were not specified. For example, if a constraint was unselected, LOG 1.01 would not save this. This meant that if the model was reloaded the user would have to unselect the appropriate constraint again. LOG 2.0 has rectified this small problem.

The maximise yield objective function option did not work correctly in version 1.01. LOG 2.0 now has this option working correctly.