Olaf David

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The environmental modeling community has historically been concerned with the proliferation of models and the effort associated with collective model development tasks (e.g., code generation, data transformation, etc.). Environmental modeling frameworks (EMFs) have been developed to address this problem, but much work remains before EMFs are adopted as(More)
Hosting a multi-tier application using an Infrastructure-as-a-Service (IaaS) cloud requires deploying components of the application stack across virtual machines (VMs) to provide the application's infrastructure while considering factors such as scalability, fault tolerance, performance and deployment costs (# of VMs). This paper presents results from an(More)
— Infrastructure-as-a-service (IaaS) clouds support migration of multi-tier applications through virtualization of diverse application stack(s) of components which may require various operating systems and environments. To maximize performance of applications deployed to IaaS clouds while minimizing deployment costs, it is necessary to create virtual(More)
— To investigate challenges of multi-tier application migration to Infrastructure-as-a-Service (IaaS) clouds we performed an experimental investigation by deploying a processor bound and input-output bound variant of the RUSLE2 erosion model to an IaaS based private cloud. Scaling the applications to achieve optimal system throughput is complex and involves(More)
  • Mark W Strudley, Timothy R Green, Robert H Erskine, Olaf David
  • 2007
The predictive capability of many environmental models is commonly hampered by a profuse set of parameters that are often physically ambiguous and costly to measure in the field. Furthermore, model parameter estimation is sometimes hindered by complex dynamical model feedbacks and interactions, resulting in the inability of many automated calibration(More)
The integration of a spatial process model into an environmental modeling framework can enhance the model's capabilities. This paper describes a general methodology for integrating environmental models into the Object Modeling System (OMS) regardless of the model's complexity, the programming language, and the operating system used. We present the(More)
— Deployment of Service Oriented Applications (SOAs) to public infrastructure-as-a-service (IaaS) clouds presents challenges to system analysts. Public clouds offer an increasing array of virtual machine types with qualitatively defined CPU, disk, and network I/O capabilities. Determining cost effective application deployments requires selecting both the(More)
  • James C Ascough Ii, Timothy R Green, Olaf David, Holm Kipka, Gregory S Mcmaster
  • 2015
AgroEcoSystem-Watershed (AgES-W) is a modular, Java-based spatially distributed model which implements hydrologic/water quality (H/WQ) simulation components under the Object Modeling System (OMS3) environmental modeling framework. AgES-W has recently been enhanced with the addition of nitrogen (N) and sediment modeling components refactored from various(More)