Eight grand challenges in socio-environmental systems modeling

Modeling is essential to characterize and explore complex societal and environmental issues in systematic and collaborative ways. Socio-environmental systems (SES) modeling integrates knowledge and perspectives into conceptual and computational tools that explicitly recognize how human decisions affect the environment. Depending on the modeling purpose, many SES modelers also realize that involvement of stakeholders and experts is fundamental to support social learning and decision-making processes for achieving improved environmental and social outcomes. The contribution of this paper lies in identifying and formulating grand challenges that need to be overcome to accelerate the development and adaptation of SES modeling. Eight challenges are delineated: bridging epistemologies across disciplines; multi-dimensional uncertainty assessment and management; scales and scaling issues; combining qualitative and quantitative methods and data; furthering the adoption and impacts of SES modeling on policy; capturing structural changes; representing human dimensions in SES; and leveraging new data types and sources. These challenges limit our ability to effectively use SES modeling to provide the knowledge and information essential for supporting decision making. Whereas some of these challenges are not unique to SES modeling and may be pervasive in other scientific fields, they still act as barriers as well as research opportunities for the SES modeling community. For each challenge, we outline basic steps that can be taken to surmount the underpinning barriers. Thus, the paper identifies priority research areas in SES modeling, chiefly related to progressing modeling products, processes and practices.</jats:p

Recent Progress on Lower-Bound Shakedown Analysis of Road Pavements

Shakedown theory has been recognised as a more rational basis for structural design of flexible road pavements. A lower-bound shakedown approach, which aims to find the maximum design load of a pavement structure, was developed by the University of Nottingham, that forms part of efforts among other researchers’ in applying shakedown theory in pavement designs. The lower-bound shakedown solutions were consistent with existing shakedown solutions assuming that the materials are isotropic and homogeneous following an associated plastic flow rule. Recently, this lower-bound approach was further developed to consider more realistic cases. Both two-dimensional and three-dimensional shakedown analyses were carried out taking into account cross-anisotropic or heterogeneous materials, the properties of which were programmed into a finite element software ABAQUS. For pavement materials obeying a non-associated flow rule, the corresponding two-dimensional lower-bound shakedown limits were also estimated by extending the lower-bound shakedown approach. A numerical step-by-step approach was also applied to address the non-associated problems and obtained similar results. Through these studies, influences of the original assumptions on the shakedown-based pavement designs can be assessed