Nonlinear systems approach to control system design

Consider some of the control system design methods for plants with nonlinear dynamics. If the nonlinearity is weak relative to the size of the operating region, then the linear methods apply directly. Fixed-gain design may be feasible even for significant nonlinearities. It may be possible to find a single gain which provides adequate control of the linear models at several perturbation points. If the nonlinearity is restricted to a sector, that fact may be used to obtain a fixed-gain controller. Otherwise, a gain may have to be associated with each perturbation point Pi. A gain schedule K(p(v)) is obtained by connecting the perturbation points by a function, say p(v), of the scheduling parameter v (i.e., speed). When the scheduling parameter must be multidimensional, this approach is difficult; the objective is to develop an easier procedure

One dimensional parabolic free boundary problems

The method of lines is used to approximate explicit and implicit free boundary problems for a linear one dimensional diffusion equation with a sequence of free boundary problems for ordinary differential equations. It is shown that these equations have solutions which can be readily obtained with the method of invariant imbedding. It also is established for a model problem that the approximate solutions converge to a unique weak and (almost) classical solution as the discretization parameter goes to zero

Is Unemployment Good for the Environment?

Environmental quality is a public good, potentially impacted by everybody. Individual level pro-environmental behavior affects environmental quality in the aggregate. Therefore, it is important to understand what causes individual’s pro-environmental behaviors to change. We quantify the causal effect of one determinant, unemployment, using an EU-27 population representative Eurobarometer survey. Drawing on results from the theory of the private provision of public goods, and recognizing that unemployment decreases income and the opportunity cost of time, we formulate testable predictions that unemployment will decrease the extent of pro-environmental behaviors that require monetary contributions and increase the extent of pro-environmental behaviors that mainly require time/effort. Instrumental variables regressions provide empirical evidence to support these hypotheses. Changes in the unemployment rate within a sub-national region provide the exogenous variation needed to identify the causal effect. Several supplemental questions on the survey provide evidence that environmental issues lose saliency and economic issues gain saliency when one becomes unemployed, suggesting that interested parties may wish to emphasize cost savings of pro-environmental behavior rather than environmental benefits during times of increased unemployment

Heterogeneity in the Preferences and Pro-Environmental Behavior of College Students: The Effects of Years on Campus, Demographics, and External Factors

Models from several social science fields have identified factors that lead to pro-environmental behavior. This research builds on those models by analyzing a survey completed by over 500 undergraduates at a US liberal arts university to examine the characteristics of students that are associated with more environmentally friendly behavior and quantify the desirability of different environmental initiatives. There is evidence that the probability of pro-environmental behavior substantially increases with each additional year that a student spends on campus. The magnitude of the effect is between 4 and 10 percentage points per year, depending on the specific behavior and empirical model. This contribution suggests that higher education impacts pro-environmental behavior and supports the notion that higher education institutions can play an important role in making societies more sustainable. Further, evidence is presented to suggest that this increase in pro-environmental behavior over one\u27s college career is due to factors outside of the formal curriculum. This study also finds that females and ethnic/racial minorities engage in significantly higher levels of green behavior including recycling and double-sided printing. On average, students prefer sustainability initiatives related to energy conservation and recycling to other environmental programs but there is a great deal of heterogeneity in these preferences

(WP 2015-02) Is Unemployment Good for the Environment?

Environmental quality is a public good, potentially impacted by everybody. Individual level pro-environmental behavior affects environmental quality in the aggregate. Therefore, it is important to understand what causes individual’s pro-environmental behaviors to change. We quantify the causal effect of one determinant, unemployment, using an EU-27 population representative Eurobarometer survey. Drawing on results from the theory of the private provision of public goods, and recognizing that unemployment decreases income and the opportunity cost of time, we formulate testable predictions that unemployment will decrease the extent of pro-environmental behaviors that require monetary contributions and increase the extent of pro-environmental behaviors that mainly require time/effort. Instrumental variables regressions provide empirical evidence to support these hypotheses. Changes in the unemployment rate within a sub-national region provide the exogenous variation needed to identify the causal effect. Several supplemental questions on the survey provide evidence that environmental issues lose saliency and economic issues gain saliency when one becomes unemployed, suggesting that interested parties may wish to emphasize cost savings of pro-environmental behavior rather than environmental benefits during times of increased unemployment

Explaining the Fixed Cost Component of Discounting: The Importance of Students\u27 Liquidity Constraints

Utilizing experimental data on choices over real monetary rewards made by university students, we provide evidence that two measures of liquidity, income and employment status, significantly explain differences in patterns of discounting. We find an average fixed cost component of discounting in the range of $5 for unemployed students and near$0 for employed students. An increase in annual disposable income of $1000 decreases the fixed cost component of discounting by approximately$0.20 to $0.25. These findings can help resolve the puzzle that some studies in the literature find evidence of present-bias and magnitude effects and some do not

Intertemporal Valuation of River Restoration

Willingness to pay for an environmental improvement is a function of how long it takes to deliver the improvement. To measure the effect of time on benefits, I utilize a discrete choice experiment that includes an attribute for delay until the improvement occurs and simultaneously estimate discount rates and valuation parameters. I estimate the present value of immediate and delayed Minnesota River Basin improvements using discount rates directly estimated from the econometric model. Compared to an immediate river basin cleanup, Minnesota residents lose almost half of the benefits when cleanup is delayed by 5 years

Response envelope - A global description of three-axis large angle spacecraft attitude control systems

Responsiveness of three axis, large angle attitude control systems of highly maneuverable spacecraft capable of tracking time-varying target attitude