Overview of Advanced Stirling and Gas Turbine Engine Development Programs and Implications for Solar Thermal Electrical Applications

The DOE automotive advanced engine development projects managed by the NASA Lewis Research Center were described. These included one Stirling cycle engine development and two air Brayton cycle development. Other engine research activities included: (1) an air Brayton engine development sponsored by the Gas Research Institute, and (2) plans for development of a Stirling cycle engine for space use. Current and potential use of these various engines with solar parabolic dishes were discussed

Component improvement of free-piston Stirling engine key technology for space power

The successful performance of the 25 kW Space Power Demonstrator (SPD) engine during an extensive testing period has provided a baseline of free piston Stirling engine technology from which future space Stirling engines may evolve. Much of the success of the engine was due to the initial careful selection of engine materials, fabrication and joining processes, and inspection procedures. Resolution of the few SPD engine problem areas that did occur has resulted in the technological advancement of certain key free piston Stirling engine components. Derivation of two half-SPD, single piston engines from the axially opposed piston SPD engine, designated as Space Power Research (SPR) engines, has made possible the continued improvement of these engine components. The two SPR engines serve as test bed engines for testing of engine components. Some important fabrication and joining processes are reviewed. Also, some component deficiencies that were discovered during SPD engine testing are described and approaches that were taken to correct these deficiencies are discussed. Potential component design modifications, based upon the SPD and SPR engine testing, are also reported

Altruism and Climate

Recognizing that individualism, or weak family ties, may be favorable to economic development, we ask how family ties interact with climate to determine individual behavior and whether there is reason to believe that the strength of family ties evolves differently in different climates. For this purpose, we develop a simple model of the interaction between two individuals who are more or less altruistic towards each other. Each individual exerts effort to produce a consumption good under uncertainty. Outputs are observed and each individual chooses how much, if any, of his or her output to share with the other. We analyze how the equilibrium outcome depends on altruism and climate for ex ante identical individuals. We also consider (a) "coerced altruism," that is, situations where a social norm dictates how output be shared, (b) the effects of insurance markets, and (c) the role of institutional quality. The evolutionary robustness of altruism is analyzed and we study how this depends on climate.altruism; family ties; individualism; moral hazard; evolution.

Kinship, Incentives and Evolution

We analyze how family ties affect incentives, with focus on the strategic interaction between two mutually altruistic siblings. The siblings exert effort to produce output under uncertainty, and they may transfer output to each other. With equally altruistic siblings, their equilibrium effort is non-monotonic in the common degree of altruism, and it depends on the harshness of the environment. We define a notion of local evolutionary stability of degrees of sibling altruism, and show that this degree is lower than the kinship-relatedness factor. Numerical simulations show how family ties vary with the environment, and how this a¤ects economic outcomes.altruism, family ties, free-riding, empathy, Hamilton's rule, evolutionary stability.

Family ties, incentives and development: a model of coerced altruism

We analyze the effects of family ties on the incentives for production of effort, where family ties are defined as a mixture of true and coerced altruism between family members. We model families as pairs of siblings. Each sibling exerts effort in order to obtain output under uncertainty. A social norm dictates that a sibling with a high output must share a specified amount of this output with his sibling, if the latter's output is low. Siblings may be truly altruistic towards each other, but not to a larger degree than dictated by the social norm. We compare such informal family insurance with actuarially fair formal insurance. We show that coerced family altruism reduces individual efforts in equilibrium. However, individuals always benefit ex ante from living in families with coerced altruism, as compared with living in autarky. We show that a certain degree of coerced family altruism is robust as a social norm in a society of selfish individuals. Finally, we show that if family members are sufficiently altruistic to each other, then informal family insurance by way of coerced altruism may outperform actuarially fair insurance programs.altruism; coerced altruism; family ties; insurance; moral hazard

The fetters of the sib: Weber meets Darwin

We analyze how family ties affect incentives, with focus on the strategic interaction between a pair of mutually altruistic siblings. Each sibling exerts effort to produce output under uncertainty and the siblings may transfer output to each other. With equally altruistic siblings, their equilibrium effort is nonmonotonic in the common degree of altruism and depends on the harshness of the environment. We define a notion of local evolutionary robustness of degrees of sibling altruism, and show that this degree is less than one half, the kinship relatedness factor. By way of numerical simulations we show that family ties are weaker in harsher environments.altruism, family ties, Hamilton's rule, free-riding, evolutionary robustness

The Fetters of the Sib: Weber Meets Darwin

We analyze the effects of family ties on the incentives for productive effort. A family is modelled as a pair of altruistic siblings. Each sibling exerts effort to produce output under uncertainty and siblings may transfer output to each other. We show that altruism has a non-monotonic effect on effort. We study how this effect depends on "climate," the magnitude and volatility of returns to effort. We also analyze the evolutionary robustness of family ties and how this robustness depends on climate. We find that family ties will be stronger in milder climates than in harsher climates.altruism; family ties; moral hazard; evolutionary robustness

Learning Together: Using Action Research to Design Professional Development

After being part of a week-long math institute, both the principal and the Mathematics Specialist from an urban school district partnered to develop a professional development plan. It incorporated a Lesson Study Model that supported collaborative learning teams, focused on the instructional process, and incorporated reflection and feedback. Although the faculty had engaged in other forms of professional development, the lesson study process was seen as a powerful vehicle that invited a level of coaching and cross-collaboration. This article focuses on the shared viewpoints of the principal and the Mathematics Specialist who worked together to build a mechanism for professional learning for improved mathematical proficiency and understanding