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

Strengthening Support for Grantees: Four Lessons for Foundations

As society becomes more interconnected, the problems nonprofits are tasked with addressing require systems work. It is imperative for funders to adapt not only to the challenges faced by the organizations they fund, but also to the dynamic social systems within which they aim to effect change. This requires new approaches that are responsive to community needs and address the known challenges in grantor-grantee relationships. This article offers a new perspective on the role of private foundations and four key lessons for strengthening funder support. These learnings build upon existing research and were gleaned from a qualitative analysis of data from interviews with 33 board members, executives, management, and front-line staff at nonprofit organizations with similar missions that serve vulnerable populations in the same locale, and with subsequently chosen funders that had relationships with those nonprofits. The interconnected challenges facing our communities are demanding more from philanthropy. Funders that build partnerships, recognize and respond to grantee reimbursement models, ease reporting burdens, and leverage their power to convene will make significant contributions to improving the resiliency of those communities

Karst Development in Northeastern Iowa

Karst landforms of northeastern lowa have developed on Silurian and Ordovician carbonate rocks through processes of dissolution and collapse. The karst areas are characterized by rapid infiltration, direct runoff into sinkholes, underground drainage through solution-enlarged fractures, bedding planes and caves, and groundwater discharge at springs. Mechanically induced karst is found along the Silurian Escarpment and in close proximity to major valleys, but the majority of northeastern Iowa\u27s karst features are solutional in origin. Collapse of rock and surficial deposits into solutional openings in underlying rock pose safety and engineering problems in the area. The direct connection of surfacewaters with shallow bedrock aquifers through sinkholes, swallows in streams, and rapid infiltration has resulted in degradation of the groundwater quality, posing possible health hazards to inhabitants of this region. These environmental problems can be reduced through recognition of the hazards posed by the presence of karst and through reasoned approaches to land management

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

Overview of the Surficial Geologic Map of the Des Moines Lobe of Iowa, Phase 3: Boone and Story counties

https://ir.uiowa.edu/igs_ofm/1021/thumbnail.jp

Surficial Geology of the Des Moines Lobe of Iowa Hancock, Kossuth, Winnebago and Wright Counties

https://ir.uiowa.edu/igs_ofm/1019/thumbnail.jp

Surficial Geology of the Stanwood (Iowa) 7.5\u27\u27 Quadrangle,

https://ir.uiowa.edu/igs_ofm/1051/thumbnail.jp