Michael G. Zentner

Perspectives on model based integration of process operations

Abstract The chemical process industry has increasingly been pursuing the use of computing technology to gather, organize, disseminate and exploit enterprise information and to closely coordinate the decisions made at the various levels of the process operational hierarchy so as to optimize overall corporate objectives. The thesis advanced in this paper is that mathematical programming models and solution methods offer the most effective tools for integration of the tactical and strategic levels of the operational hierarchy. To that end, existing strategies for implementing model-based integrated applications are reviewed. Four classes of examples of integration are presented: scheduling of multiproduct plants, large-scale model predictive control, integration of planning and scheduling across single and multiple plant sites and design of multipurpose batch plants under uncertainty. The methodology used to address these model-based integration instances successfully accomodates the key features of process operations: diverse time scale, multiple reference frameworks, spatial and organizational aggregation/disaggregation and uncertainty in the enterprise information. The applications further demonstrate that for the foreseeable future no single model or reference framework will be sufficient and efficient for treating all aspects of the process operations hierarchy.

Practical considerations in using model-based optimization for the scheduling and planning of batch/semicontinuous processes

Abstract Over the last few years, there has been a proliferation of research, industry in-house projects, and new products for automating and improving chemical process industry (CPI) scheduling and planning activities. The principal reason for this proliferation has been the increased global competition within the CPI and a concomitant drive to reduce costs and improve profitability. This paper begins with a description of the issues involved in solving scheduling problems, then discusses a model-based framework for addressing these problems, and finally provides techniques by which models can be constructed for practical applications and solved with modest computational effort. The techniques are illustrated with test problems from the literature and, in the case of a CHES challenge problem, we provide the first optimal solution reported to date. A key point throughout the paper is the effectiveness of using multiple layers of problem representation to separate the high level problem description from its lower level mathematical models and the methods used for their solution.

Science gateways today and tomorrow: positive perspectives of nearly 5000 members of the research community

Science gateways are digital interfaces to advanced technologies that support science/engineering research/education. Frequently implemented as Web and mobile applications, they provide access to community resources such as software, data, collaboration tools, instrumentation, and high‐performance computing. We anticipate opportunities for growth within a fragmented community. Through a large‐scale survey, we measured the extent and characteristics of the gateway community (reliance on gateways and nature of existing resources) to understand useful services and support for builders and users. We administered an online survey to nearly 29,000 principal investigators, senior administrators, and people with gateway affiliations. Nearly 5000 respondents represented diverse expertise and geography. The majority of researchers/educators indicated that specialized online resources were important to their work. They choose technologies by asking colleagues and looking for documentation, demonstrated reliability, and technical support; adaptability via customizing or open‐source standards was another priority. Research groups commonly provide their own resources, but public/academic institutions and commercial services also provide substantial offerings. Application creators and administrators welcome external services providing guidance such as technology selection, sustainability planning, evaluation, and specialized expertise (e.g., quality assurance and design). Technologies are diverse, so flexibility and ongoing community input are essential, as is offering specific, easy‐to‐access training, community support, and professional development. Copyright

Science Gateways Institute Survey

Science gateways are digital interfaces to advanced technologies that support science/engineering research/education. Frequently implemented as Web and mobile applications, they provide access to community resources such as software, data, collaboration tools, instrumentation, and high‐performance computing. We anticipate opportunities for growth within a fragmented community. Through a large‐scale survey, we measured the extent and characteristics of the gateway community (reliance on gateways and nature of existing resources) to understand useful services and support for builders and users. We administered an online survey to nearly 29,000 principal investigators, senior administrators, and people with gateway affiliations. Nearly 5000 respondents represented diverse expertise and geography. The majority of researchers/educators indicated that specialized online resources were important to their work. They choose technologies by asking colleagues and looking for documentation, demonstrated reliability, and technical support; adaptability via customizing or open‐source standards was another priority. Research groups commonly provide their own resources, but public/academic institutions and commercial services also provide substantial offerings. Application creators and administrators welcome external services providing guidance such as technology selection, sustainability planning, evaluation, and specialized expertise (e.g., quality assurance and design). Technologies are diverse, so flexibility and ongoing community input are essential, as is offering specific, easy‐to‐access training, community support, and professional development. Copyright

An Interval-Based Mathematical Model for the Scheduling of Resource-Constrained Batch Chemical Processes

This paper is an extension of previously presented work concerned with the use of. interval analysis and search techniques for the exact modelling of the solution space of resource-constrained batch chemical process scheduling problems. A mathematical programming formulation is presented which is based on the notion of interval analysis and which uses a non-uniform discretization of time derived only from real process events. No additional discretization variables are introduced. While conventional discretization models rely on the rounding of problem data in order to reduce the size of the formulation, the base formulation proposed here does not require such data modification. The importance of this difference is that, although a conventional discretization model can be solved exactly, an exact solution is found to an approximate problem; whereas the model proposed here is not sensitive to the timing of events and therefore always gives an exact representation of the problem data with minimal discretization. However, added expense is incurred by the introduction of sequencing variables and constraints. Preliminary comparison with existing mixed integer formulations indicates promise for drastic reduction in model size for certain types of problems.

Learning and research in the cloud

Research and teaching in nanoscience can, and should, be thought as one joint endeavour. nanoHUB, a cyberinfrastructure that aims to use interactive cloud-based software to meet the needs of both code developers and end-users, is redefining research and education in nanoscience and engineering.

nanoHUB.org: cloud-based services for nanoscale modeling, simulation, and education

Abstract nanoHUB.org is arguably one of the most successful science gateways funded by the National Science Foundation (NSF). It is the cyberinfrastructure that supports the Network for Computational Nanotechnology (NCN), currently serving over 240,000 users annually in 172 countries worldwide. It features a range of resources including seminars, online courses, short courses, full-fledged tool-powered curricula, and over 260 online simulations and modeling tools. nanoHUB functions as a scientific cloud where users cannot only design and run their tools but also provide a worldwide audience access to these tools with no installation or minimal infrastructural requirements on the users’ part.

Who cares about science gateways?: a large-scale survey of community use and needs

With the rise of science gateway use in recent years, we anticipate there are additional opportunities for growth, but the field is currently fragmented. We describe our efforts to measure the extent and characteristics of the gateway community through a large-scale survey. Our goal was to understand what type of support services might be provided to the gateway community.

Social Networks of Researchers and Educators on nanoHUB.org

The science gateway nanoHUB.org is the worlds largest nanotechnology user facility, serving 167, 196 users in 2010 with over 2,300 resources including 189 simulation programs. Surveys of nanoHUB users and automated usage analysis find widespread simulation use in formal classroom education, thereby connecting recent research more rapidly and closely to education. Analysis of 719 citations in the scientific literature by over 1,300 authors to nanoHUB.org resources documents use of simulation programs by new research collaborations, by researchers outside of the community originating the program, and by experimentalists. The publication and author networks reveal research collaborations and capacity building through knowledge transfer. Analysis of secondary citations documents the quality of the conducted research with an h-index of 30 after just 10 years of operation. Our analysis proves with quantitative metrics that impactful research can be conducted by an ever growing research community. We argue that HUBzeroTM technology and the user-focused design and operation of nanoHUB.org are keys to success that can be transferred to other science gateways.

Science Gateways: The Long Road to the Birth of an Institute

Nowadays, research in various disciplines is enhanced via computational methods, cutting-edge technologies and diverse resources including computational infrastructures and instruments. Such infrastructures are often complex and researchers need means to conduct their research in an efficient way without getting distracted with information technology nuances. Science gateways address such demands and offer user interfaces tailored to a specific community. Creators of science gateways face a breadth of topics and manifold challenges, which necessitate close collaboration with the domain specialists but also calling in experts for diverse aspects of a science gateway such as project management, licensing, team composition, sustainability, HPC, visualization, and usability specialists. The Science Gateway Community Institute tackles the challenges around science gateways to support domain specialists and developers via connecting them to diverse experts, offering consultancy as well as providing a software collaborative, which contains ready-to-use science gateway frameworks and science gateway components.