Nimrod/O: A Tool for Automatic Design Optimisation Using Parallel and Distributed Systems

Abstract

This paper describes a novel tool called Nimrod/O that allows a user to run an arbitrary computational model as the core of a non-linear optimization process. Nimrod/O allows a user to specify the domain and type of parameters to the model, and also a specification of which output variable is to be minimized or maximized. Accordingly, a user can formulate a question like: "what parameter settings will minimize the model output?". Nimrod/O currently employs a number of built-in optimization algorithms, namely BFGS, Simplex, Divide and Conquer and Simulated Annealing. Jobs can be executed on a variety of platforms, including distributed clusters and Computational Grid resources. The paper demonstrates the utility of the system with a number of case studies.

EA-based Problem Solving Environment over the GRID

“…Folding@Home has not provided optimization solving problem solving environment, yet it is a well known example of how aggregated resources when combined can address new problem scope. Nimrod/O (Abramson et al, 2000): A very significant project as the authors not only designed the problem solving environment but they also added and modified the grid middleware to adapt with the grid application. Nimrod/ O offers namely 4 optimization solving packages solving non-linear optimization problems, but it doesn't allow the user to add his own solver and limits him/ her to the provided solvers.…”

“…The middleware is a software layer that resides between an application and the underlying platform, in grids the middleware hides the underlying low-level details and complexities from the application layer. Yet, practically in grids, a big semantic gap lies between the middleware and the application layer, so (Abramson, 2006) revised the traditional architecture and modified it by splitting the middleware layer into two layers, the upper middleware layer and the lower middleware layer. This architecture was adopted in MHGrid due to its enhanced subjective representation and ease of modelling.…”

Model Optimization and Parameter Estimation with Nimrod/O

“…The task [12,5,7] was to minimize the ozone concentration within a range of values for N and R, the concentrations of oxides of nitrogen and reactive organics respectively. Since ozone concentration is not a monotonic function of the input concentrations, the minimum does not necessarily correspond to least N and R.…”

“…The design of a test rig for mobile telephone antennas included a ferrite bead to reduce distortion of the radiation pattern [5,7]. The finite-difference timedomain technique was used to solve Maxwell's equations for the design.…”

Incorporation of Middleware and Grid Technologies to Enhance Usability in Computational Chemistry Applications

“…From the end-user perspective, submitting a workflow to the grid involves interaction solely with the web portal interface, a user interface to the middlware described above, or a grid scheduler such as NIMROD [12]. That is, the underlying grid components are hidden from view for day-to-day application operations.…”