Fall 2001
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Welcome to the inaugural issue of the GoldSim Newsletter! Starting with this issue, we will be publishing a quarterly e-newsletter and sending it to the GoldSim community. Our goal is to provide information to help you get the most out of GoldSim. We also hope that the Newsletter can act as a vehicle to build connections between users within the GoldSim community.

Each newsletter will deliver the latest GoldSim news (e.g., regarding updates and new versions), as well as a number of regular items. This will include a Featured GoldSim Application, tips from the GoldSim developers, a list of new models added to the GoldSim Model Library, a list of new GoldSim Knowledge Base articles, and a description of new features that the GoldSim Development Team is currently working on. Each Newsletter will be archived on our website so you can revisit old issues.

Since this newsletter is for you, we encourage you to send us your comments and contributions. If you send us a contribution and we use it, we will acknowledge you in the Newsletter. Send your contributions to newsletter@goldsim.com.

The GoldSim Development Team

User Conference Rescheduled to April 2002

Due to the tragic events of September 11, the 2001 User Conference scheduled for September was cancelled. The Conference has been rescheduled to April 2002. The Conference will be held in Redmond, Washington on Thursday and Friday, April 25 - 26, 2002. Prior to the conference, a three-day GoldSim training course will be held for new GoldSim users on April 22-24. In addition, for existing users, a set of FREE advanced training seminars will be held on Wednesday, April 24.

The User Conference will be a terrific opportunity for users to share experiences with each other and with the GoldSim developers, and to provide input for the future development of GoldSim. We hope you can attend.

GoldSim Version 7.3 to be Released by Year End

The next version of GoldSim (Version 7.3) will be released by year end. In addition to numerous minor changes, refinements and bug fixes, this version will have a number of important modifications and new features, including the following:

  • Expressions entered into input fields within GoldSim are now color-coded (i.e., output names, functions, operators, and units are displayed in different colors). This makes expressions much easier to read (and enter).

  • Several elements have been renamed. An Accumulator becomes an Integrator. An Event Generator becomes a Timed Event. A Consequence Generator becomes a Discrete Change.

  • The integration algorithms for Reservoirs and Integrators (formerly called Accumulators) have been modified and improved. Both of these elements integrate continuous signals. Version 7.3, however, encourages users to distinguish between the movement (and integration) of materials and the movement (and integration) of information. A Reservoir is intended to integrate materials and represents a "stock" of something (e.g., water, widgets). An Integrator simply integrates a signal (information). Because material and information movement are conceptually and mathematically distinct (materials are conserved, information is not), these are represented by two separate elements.

  • Two powerful new Delay elements have been added: a Material Delay and an Information Delay. These delay elements delay continuous signals (which can optionally also be dispersed in transit). For example, to simulate the movement of water through the unsaturated zone you would specify a flow rate into the delay, the mean travel time required to move through the zone, and the degree of dispersion in transit (which would be 0 for a plug flow system). The output of the Material Delay would then be a delayed and dispersed flow rate. Material Delays can be used for a wide variety of systems, such as the movement of parts through a supply chain, the movement of vehicles in a transportation system, or the movement of waste material around a mine. In addition to delaying material flows, in some systems it is also important to delay information flows (e.g., an order is placed, but the order is not received for two days). Like Reservoirs and Integrators, Material and Information Delays are conceptually and mathematically distinct (materials are conserved, information is not), and are therefore represented by two separate elements.

  • Two new input entry elements have been added: Material Input Histories and Information Input Histories. These specialized look-up table elements are designed to make input of large time histories (e.g., rainfall and other historical records) very easy. You can enter data and identify what it represents (e.g., a quantity, an instantaneous flow rate, a flow rate over next time interval, discrete additions), and ask GoldSim to automatically convert the data to a form that is appropriate for use in the model. For example, you could enter a table of daily precipitation rates (i.e., a flow rate over a specified interval), and GoldSim would correctly represent them as such, regardless of the timestep used in the model.

  • A number of new elements to support discrete event simulation (Decision, Milestone, Status, Triggered Event, Discrete Change Delay) have been added. Coupled with a reworking of the mechanism for triggering elements (e.g, such as Consequences, Conditional Containers, and Stochastics), these modifications will be particularly useful for simulating decision logic and project strategies.

  • "Versioning" of a model file will be supported. Versioning allows you to track changes to a model file over time, and is particularly useful for large, complex models.

Note that the manuals will be significantly modified to reflect the changes in this version, so if you were thinking about downloading and printing the manuals, you may want to hold off until this version is released. In addition, due to the large number of changes, some of which have the potential to affect currently existing models (e.g., new integration algorithms), a short memo will be produced to help users smoothly migrate to the new version.

GoldSim User Survey

Within the next week, we will be sending an electronic survey to each member of the GoldSim User Community. The survey will include questions regarding your general use of GoldSim and the support provided by the GoldSim Consulting Group. Our hope is that the results of this survey will help us to better understand the needs of our users. Each person that completes the survey will be entered into a drawing to win a $100 gift certificate from Amazon.com.


Modeling Long-Term Health and Environmental Risk at the Nevada Test Site

John Tauxe
Neptune and Company
Los Alamos, New Mexico USA

The Environmental Management office of the National Nuclear Security Agency at the Nevada Test Site (NTS) manages low-level radioactive waste at facilities near the town of Mercury, northwest of Las Vegas, Nevada. Management of these facilities is entering a new phase following previously-conducted compliance assessments. Post-compliance objectives fall under the domain of continued maintenance and include closure, long-term monitoring and continuing disposal operations. The new objectives require a complete probabilistic analysis of the environmental system coupled with a model of cost and potential liabilities in order to capture the impact of actions that might be taken to mitigate long-term human health or environmental risks. Neptune and Company, an environmental consulting firm, is currently implementing this fully coupled environmental management system using GoldSim. One component of the management system that is under construction is a fully probabilistic model of one type of waste disposal configuration at the NTS, referred to as the Greater Confinement Disposal boreholes. Some of these large diameter boreholes contain classified transuranic waste buried below a depth of 21 m and backfilled with native alluvium. The GoldSim model simulates the migration of contaminants from these boreholes to the ground surface. The dominant contaminant transport processes at this arid site are upward advection and biotic translocation.


If you want to determine if element A affects element B in a model that is very complex, use the Affects list in combination with GoldSim's search feature. Right-click on A and select Affects. When the browser appears, do a search for B in the list. In version 7.3, a search bar will appear directly on the browser. In previous versions, you can access the search by pressing Ctrl+F.



The GoldSim Model Library allows GoldSim users to build on the experience and knowledge of others by sharing models. The Library is available from within the GoldSim Members Area. If you have a model that you think would be worthwhile to post to the library, please send it, along with text describing the model, to library@goldsim.com.

You can search the Model Library by keyword and category (e.g., Contaminant Transport, Financial, Water Resources).

We encourage you to visit the Library (and submit new models). To keep you updated on additions to the Library, all new models added to the Library will be summarized in the Newsletter each quarter.


The GoldSim Knowledge Base contains articles addressing frequently asked questions, workarounds for known problems, and advice on applying GoldSim. The Knowledge Base is available from within the GoldSim Members Area.

You can search the Knowledge Base by keyword and/or module.

We encourage you to visit the Knowledge Base, as even expert users are likely to find useful information there. To keep you updated on additions to the Knowledge Base, all new articles added to the Knowledge Base will be listed in the Newsletter each quarter.


As most users are aware, we are constantly adding new features to GoldSim, based on feedback from our own modelers, as well as those of our clients, partners and customers.

In addition to the many minor improvements that we continuously make to the software, we are currently working on two new GoldSim modules:

  • Replication Module. This module will represent our first step toward integrating GoldSim with geographic information systems (GIS). Such a linkage would enable a user to combine the spatial modeling tools of a GIS with the dynamic modeling capabilities of GoldSim. In this first step, we will allow a user to define template models (sub-models in containers) that GoldSim automatically replicates across a user-specified grid. The template models will be defined such that the replicated containers will be able to communicate between grid cells (e.g., a model could reference an output from adjacent grid cells).

  • Financial Module. This module will make simulating the financial aspects of models (e.g., modeling a project or a company, evaluating investment and financing decisions) much easier and more powerful. This first version of the Financial Module will primarily consist of additional elements and features to facilitate capital budgeting and cost accounting.

We hope to release both of these modules by the middle of 2002.

In addition, by early 2002, we expect to add an Index to all of the manuals, as well as on-line Help and Tutorials.


2001 Golder Associates Inc. If you wish to unsubscribe to this Newsletter, visit our website www.goldsim.com/enews. If this Newsletter was forwarded to you by someone else, and you wish to subscribe, you can also do so at www.goldsim.com/enews.