An integer programming approach to the Hospitals/Residents problem with ties

The classical Hospitals/Residents problem (HR) models the assignment of junior doctors to hospitals based on their preferences over one another. In an instance of this problem, a stable matching M is sought which ensures that no blocking pair can exist in which a resident r and hospital h can improve relative to M by becoming assigned to each other. Such a situation is undesirable as it could naturally lead to r and h forming a private arrangement outside of the matching. The original HR model assumes that preference lists are strictly ordered. However in practice, this may be an unreasonable assumption: an agent may find two or more agents equally acceptable, giving rise to ties in its preference list. We thus obtain the Hospitals/Residents problem with Ties (HRT). In such an instance, stable matchings may have different sizes and MAX HRT, the problem of finding a maximum cardinality stable matching, is NP-hard. In this paper we describe an Integer Programming (IP) model for MAX HRT. We also provide some details on the implementation of the model. Finally we present results obtained from an empirical evaluation of the IP model based on real-world and randomly generated problem instances

Study of thin film large area photovoltaic solar energy converter final report

Process for fabricating thin film cadmium sulfide backwall solar cells on polyimide plastic foil substrate

Study of thin film large area photovoltaic solar energy converter Second quarterly report, 1 Jan. - 31 Mar. 1963

Thin film large area photovoltaic solar energy converter - cadmium sulfide films producted by vacuum evaparation techniqu

Study of thin film large area photovoltaic solar energy converter First quarterly report, 25 Oct. 1965 - 24 Jan. 1966

Cadmium sulfide thin film photovoltaic cell for large area solar energy converte

France to Haiti to Spain to Cuba to America: Immigration Across Cultures and History

Growing up hearing stories about relatives throughout the United States, Carribbean, South America, and Europe, I was unaware of the uniqueness of my family’s journey over the last several generations. Where did my family come from, how far can I trace it back, what factors led to their convoluted multi-generational immigration and how did my grandfather, Fernando Villa, come to know Fidel Castro? In particular, what circumstances surrounded the move from Cuba to the United States and what was the transition like for a first-generation immigrant family? Research was designed to focus on historical literature and oral interviews with my 95 year old grandfather, Fernando Villa, who immigrated to the United States in 1955. I also conducted supplementary research through other media formats and interviews with family figures knowledgeable on our family’s history. Discussion focused around three major areas: direct family history, growing up in a Cuban family, and commentary on social and political issues and their effect on Fernando’s immigration to the United States with his family. The resulting conversations and research revealed many details of the complex Villa family tree, stretching across three continents and involving immigration across the ocean four times. They also exposed the professional reasons, exacerbated by the political climate in Cuba, for my grandfather’s choice to leave Cuba for America. From the research, I found the cultural history of the Villa family to be deeper and wider than previously thought. The actions of my ancestors were often driven by major world events studied in textbooks at every school, and their stories are personally intertwined with locations and people known around the world

Development of cadmium sulfide thin film photovoltaic cells third quarterly report, apr. 15 - jul. 14, 1965

Cadmium sulfide thin film photovoltaic cells - cadmium sulfide film evaporation, cell testing, improvement, and stability, and plastic and metal substrate cell

Study of thin film large area photovoltaic solar energy converter Second quarterly report, 25 Feb. - 24 May 1966

Cadmium sulfide thin film solar cell developmen

The Primary Solid Waste Storage Gaps Experienced By Nairobi Households

This study identifies and analyses the solid waste management service gaps and situations in these different socio-economic setups. The objectives of this study were: (i) To assess households’ current bin types; (ii) To assess households’ desired bin types; and (iii) To identify the bin gaps experienced by households. A total of 430 households were selected through stratified sampling from dwellings with different social status, as represented by estate to give the quantitative data. The qualitative methods such as key informant interviews, observation surveys, and secondary data were also used. All the 8 divisions in Nairobi were represented, in a ratio proportionate to households from slums, low income, and middle income estates. There is a bin gap of about 15% households needing bucket; 26% excess plastics; and a deficit of 12% households needing but short of metal bins; and a 6% deficit of the 5-10litre bins; a 13% excess of bins less than 5 litres; 1.6% deficit of 10-15 litre bins, and 14 % deficit of households needing bins larger than 20 litres. 30% of households have heavy to very heavy bins. Entrepreneurs should improve availability of storage bins of correct specification (size, material and make) as preferred by various households. Correct specifications of garbage bins should be designed to satisfy these household needs.Key Words: Household Storage, Solid Waste Management; Garbage Bin