Optical control of solar sails using distributed reflectivity

The dynamics of solar sails with a variable surface reflectivity distribution are investigated. When changing the reflectivity across the sail film, which can be achieved using electro-chromic coatings, the solar radiation pressure forces and torques across the sail film can be controlled without changing the attitude of the spacecraft relative to the Sun and without using mechanical systems. The paper presents two approaches. First, a continuous reflectivity distribution is presented to control the sail attitude under the influence of, for example, gravity gradient torques in Earth orbit. The second approach assumes discrete on/o reflectivity regions across the surface. Both concepts of `optical reconfiguration' of solar sails enable a more flexible steering of the spacecraft and minimize actuation effort

Numerical methods for ground simulation of satellite motion

Environmental models applicable for purposes of mission analysis were developed, documented, and recommended. The findings are described

The risk of climate ruin

How large a risk is society prepared to run with the climate system? This is a question of the utmost difficulty and it admits a variety of perspectives. In this paper we draw an analogy with the management and regulation of insurance companies, which are required to hold capital against the risk of their own financial ruin. Accordingly, we suggest that discussions about how much to reduce global emissions of greenhouse gases could be framed in terms of managing the risk of ‘climate ruin’. This shifts the focus towards deciding upon an acceptable risk of the very worst-case scenario, and away from how “avoiding dangerous anthropogenic interference with the climate system” has come to be framed politically. Moreover it leads to the conclusion that, in terms of greenhouse gas emissions today and in the future, the world is running a higher risk with the climate system than insurance companies run with their own solvency

Teaching of mass communication law : the examination of three methods of instruction and the use of those methods in an undergraduate course

It may be the influence from the field of advertising, I'm not sure. Somewhere along the way I developed the ideology that how infomi.ation is presented in the classroom is just as important as the course's content. That line of thought, combined with my interest in media law, led to this study. , A challenge faced by communication law professors is how to organize a large body of information and present it in some understandable manner so that students will retain at least a portion of the information afterexitingthe classroom door. This is no easy task considering the growing number of court decisions affecting free speech and the free press and the unique but subtle differences between each of the decisions. The three methods of classroom instruction for a media law course that were included in this study were the Socratic� ~ethod, theoretical framework approach, and the media studies method. Each method has unique characteristics that set it apart from the others. Because the body of information concerning communication law continues to grow, educators need to be aware of and open to the different methods of instruction for such a course. As precedents pile upon precedents, both new and veteran communication law professors also need to understand the various resources that are available. Without examining new techniques an~ new resources, educators will never be aware of the alternatives available to them. I believe that it is essential for educators to constantly reevaluate how they present information in their classroom. To teach a class the same way every semester year after year just because "we've always done it that way" may be the most damaging attitude in higher education. If our goal is to disseminate information and encourage students to do further study on their own, we must take a critical look at what we are doing and be willing to make some radical changes.Mass Communication

Surficial geologic materials of the Des Moines Lobe of Iowa, Phase 7: Osceola County

https://ir.uiowa.edu/igs_ofm/1039/thumbnail.jp

Surficial geologic materials of the Des Moines Lobe of Iowa, Phase 6: Dickinson and Emmet Counties

https://ir.uiowa.edu/igs_ofm/1033/thumbnail.jp

Surficial geologic materials of the Des Moines Lobe of Iowa, Phase 7: Clay County, Iowa

https://ir.uiowa.edu/igs_ofm/1038/thumbnail.jp

Surficial Geology of Montgomery County, Iowa

https://ir.uiowa.edu/igs_ofm/1095/thumbnail.jp