Search

Traditional product architecture design is motivated towards structural-functional modularity by a flat map all-in-one (AIO) approach, providing little emphasis on interface complexity and addressing conflicting goals. The resultant modular product architecture (PA) often reduces design robustness and increases complexity for product assembly and recovery. Sometimes, the generated architecture is inconsistent with efficient final assembly, increasing redesign costs. To overcome such problems, this paper proposes a sustainable modular product architecture (SMPA) to reduce assembly complexity and middle-aged discarding of products by enhancing assemblability and recovery. For achieving sustainability in modular design, three sustainable modular drivers—namely, product configuration cost, interface complexity and material similarity—are considered along with several architectural drivers. The key challenge for incorporating sustainability consideration into the existing modularization theories and methods are the heterogeneity between different goals and the decision criteria. To deal with this challenge of decision hierarchy, a bi-level leader-follower joint optimization (LFJO) model is formulated as a Stackelberg game, combining the architectural and sustainability factors of modular design. The main objective is to determine the optimal level of module granularity to reduces assembly cost and enhance product recovery within a coherent framework of total product configuration cost (TPCC) and total interface complexity (TIC). A switching based bi-level meta-heuristic algorithm (SBMA) is developed incorporating Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) to solve the bi-level LFJO problem. A case study of a refrigerator modular design reveals that the joint optimization of product configuration design and interface complexity excels sustainability characteristics of modular design.

1. Shallow groundwater aquifers regularly support drought refuges for water-dependent ecosystems. However, many aquifers are impacted by over-extraction and pollution, potentially degrading their ability to support groundwater-fed drought refuges. 2. We investigated the response of groundwater-connected riverine forests to a drought considered equivalent in intensity to those predicted under severe climate change for 2030. The drought’s impact was investigated in an area where shallow groundwater resources are heavily exploited and polluted by salinization. 3. We used remotely sensed vegetation productivity (enhanced vegetation index) data from a long-term data set (2000–2011) at 475 riverine forest sites in the Campaspe catchment, southeastern Australia. Generalized additive mixed models and boosted regression trees were used to model the relationship between groundwater and other environmental covariates with forest change during drought. 4. Models explained up to 44% of the variation in forest change during drought. Forests underwent the greatest declines in areas of high salinity (>6000 lS cm-1) associated with shallow groundwater depths (0–5 m). Conversely, forests in areas of lowest salinity (

Sustainable groundwater resource management can only be achieved if planning processes address the basic dynamics of the groundwater system. Conceptual and distributed groundwater models do not necessarily translate into an understanding of how a plan might operate in reality. Prompted by Australian experiences, ‘iterative closed-question modelling’ has been used to develop a process of iterative dialogue about management options, objectives and knowledge. Simple hypothetical models of basic system dynamics that satisfy agreed assumptions are used to stress-test the ability of a proposed management plan to achieve desired future conditions. Participants learn from models in which a plan succeeds and fails, updating their assumptions, expectations or plan. Their new understanding is tested against further hypothetical models. The models act as intellectual devices that confront users with new scenarios to discuss. This theoretical approach is illustrated using simple one and two-cell groundwater models that convey basic notions of capture and spatial impacts of pumping. Simple extensions can address uncertain climate, managed-aquifer recharge and alternate water sources. Having learnt to address the dynamics captured by these models, participants may be better placed to address local conditions and develop more effective arrangements to achieve management outcomes.

In many parts of the world, assuring reliable supplies of potable water is a serious challenge. It is not simply a matter of imposing restrictions on supply, increasing water prices, and building new dams. Effective water security strategies can only be developed when the mechanisms of supply and demand and the interactions between are fully understood. A System Dynamics (SD) modeling approach is taken to collect, analyze and merge the views of both consumers and supply managers in order to develop conceptual models which then form the basis for building quantitative models to investigate the complex dynamics. The modeling process has led to a significant increase in the understanding of the management of water security. First, the process has reinforced a number of lessons learned by SD modelers over the years, and second, the process has exposed a significant number of mis-perceptions about water security among supply managers and consumers.