Growing concern about climate change and energy security has led to increasing interest in developing domestically available renewable energy sources for meeting the electricity, heating and fuel needs in the United States. Illinois has significant potential to grow perennial grasses that can provide bioenergy. Recent research on miscanthus has shown that this low-input perennial may have biomass yields that are twice that of switchgrass and corn. Land requirements from growing biomass crops compete with existing profitable land uses, which in the case of Illinois, is primarily in row crop agriculture. This study examines the conditions of switching land from row crops to energy crops which are expected to vary across the landscape in Illinois, depending on soil quality and climatic conditions. To find the optimal land allocation among competing uses we will use spatial dynamic modeling tools combined with data from Geographic Information Systems (GIS) on land quality, climate and land use. The Spatial Modeling Environment (SME) allows inclusion of spatially enabled dynamic models to combine system-dynamics and agent-based modeling approaches. Four major crops are compared, including corn, soybeans, miscanthus, and switchgrass.
This years peer review dialog meeting will take up what participants have articulated last year and what the Policy Council has undertaken in the meantime.
Briefly put: even though the final decision is up to the programme committee, formally deficient papers would be rejected without revision, formally deficient reviews would lead to suspending the reviewer for one year, authors of accepted papers would evaluate the reviews usefulness and reviewers would have a discussion forum in order to collaborate.
One conference later, we shall ask how the actual process related to the planned one, on the basis of last years report and the PCs response to it. Well also assess how it worked this time, indicate what has been achieved and what seems to need improvement. We shall conjointly set up a set of recommendations, too.
Since the 50s, there have been voices that governments should cease to operate schools and limit themselves to financing it via a voucher system and controlling schools compliance to quality standards. In the early 80s, this has been implemented in Chile. There are three types of schools: private ones freely charge fees, private subsidized that have a limited fee and public. The quality and equality of the school system fall short of expectations. This paper proposes a qualitative model to explain what is going on. Families are assumed to prefer higher performing schools, teachers prefer better labor conditions and schools prefer favored pupils and better teachers. Richer schools attract more favored families that enable improved results due to the favored-pupil effect; additionally their ability to charge higher fees allows them to attract the best teachers, which further enhances their advantage. We find 5 positive feedback loops. The result is a process of concentration of favored pupils and good teachers that increases inequality. It is concluded that there are unequal conditions amongst the types of schools, and as long as they persist, no initiative in favor of more equality will succeed
Polarity and causality are important concepts but have not received much attention in the system dynamics literature. The great effort it takes students to properly understand them has motivated this inquiry. In the framework of a conceptual model of interacting with complex systems, several cognitive tasks are proposed. This paper concentrates on one of them that deals with causal links polarity. An examination of other approaches that deal with causality and use more or less similar diagram languages shows that usually causality is only very broadly defined, and where it is operationally defined, this is done with respect to events rather than behavior. In contrast to these approaches, system dynamics is about behavior rather than events. We then revisit the traditional criticism of causal loop diagrams and show a way out, but add two new criticisms related to the inability of causal loop diagrams to address behavior: in fact it seems that they are closer to the event-related definition of causality. Also, the impossibility to execute them in simulations means that executable concept-models are to be preferred: they express important information a causal loop diagram cannot represent and on top of it they render the behavioral consequences visible (as opposed to the events).
So as to stabilize the atmospheric greenhouse gas concentrations at tolerable levels, global emissions should dramatically be reduced soon within this century. To achieve this end, a long term global cooperation and developing country participation is essential. In this paper, we take the Contraction and Convergence framework first proposed by the CSE of India as one possible treaty and investigate the long term abatement and trading behavior of countries with economic growth. Dynamic simulation based economic experiments is the method. Seven countries with potential buyers and sellers trade permits in the global market for 25 years. For each simulated year, asks and bids of the countries /regions are collected and permit prices are set at the equilibrium price. In the first treatment, annual national quotas expire each year and the countries cannot save their allowances. In the second treatment, the countries are allowed to transfer quota surplus /deficit up to 30 /20 percent of their annual emissions to the next year. One hypothesis is that, neither the developed nor the developing countries will make sufficient timely reductions and they will create unanticipated costs for their economies as the quota prices increase over the years. An implication of this result is global cooperation being threatened under more stringent reduction requirements and increasing costs of compliance.
Delays are one specific factor contributing to misperceptions of dynamics. An experimental study was conducted to investigate how different representations of delays in the decision making interfaces (DMIs) may affect peoples ability to manage and understand a dynamic system. A simple production-inventory management game was developed with four distinct DMIs, each featuring the production delay in a different way. Subjects were assigned randomly to use one of the four DMIs and a single-subject, think-aloud experimental protocol was deployed to gather data on the decision making process. No vivid impact of the different representations of the delay in the DMI was observed. However, data gathered through the single subject experimental protocol suggest that the subjects do not follow the anchoring and adjustment rule proposed earlier (see Sterman 1989). Rather, they develop a simplified decision rule that is not robust to changes in the task settings but that is successful in the context of the particular experimental task.
This paper presents a System Dynamics approach to analyzing the violence and widespread death and displacement in Darfur, Sudan, as observed since 2003. We lay a foundation for using simulation to investigate the underlying structure and effects of violence; model analysis indicates that presently the dynamics may be driven by the population at risk more so than aggressor intent. This model can aid in future policy analysis and establishes a foundation for using System Dynamics to understand the structure and pattern of genocide. We present several challenges to analyzing the Darfur crisis including observability, information delays, and the choice of metrics. Finally we discuss modeling results and options for intervention and propose several policy questions and areas for future research.
The UK health and social care systems are continuously changing over time. Other authors have previously put a strong case for usage of system dynamics (SD) in this area largely because SD address issues of system complexity and identification of feedback loops, resulting in a greater insight into this problem situation.
This paper presents research carried out in two areas of SD, firstly the conceptualizing of a problem and secondly the building of a SD model related to the dynamic problem of bed blocking in the UK health and social care domain. A case study approach has been applied to a hospital discharge department and elderly wards in a main UK hospital.
This paper provides a useful insight into issues that have occurred when conceptualizing and formulating a health and social care SD model. System behavior has been discussed as has the use of causal loop diagrams and stock and flow diagrams. Causal loop diagrams and stocks and flows have shown to play a useful part in overcoming SD difficulties. SD has proved to be a useful method in helping to gain an insight into the dynamics of a health and social care system. This is a preliminary paper, future papers will expand on this to look at policy experiments and sensitivity tests.
This paper proposes several alternative methods to improve system dynamics models used in the literature for generation expansion planning in liberalised electricity markets. Concretely, these methods provide a better representation of oligopoly structures and market power. These improvements focus on market price and productions calculations, future markets modelling and companies differentiation when deciding new investments. The methods presented in the paper are based on equilibrium approaches and credit risk theory.
Building upon previous work in the field of system dynamics, a generic model of multiple improvement programs is outlined. The model is used to create insightful stories on success and failure in process improvement initiatives. The simulation experiments reveal that plants should strive for implementation patterns that focus on programs exhibiting higher organizational complexity rather than technical complexity. Furthermore, the simulation analyses provide insights in the interplay between organizational learning, program commitment, and process improvement. The value of the conducted approach lies in the explicit investigation of the impact of varying improvement program patterns on plant performance.