This research is aimed to study the system performance for a large solar hot water system constructed by connecting a series of small domestic natural circulation systems. There are few studies on this type of large solar hot water system available. The major concern is that when circulation pump is on, there forms a short flow between inlet and outlet of each storage tank of natural circulation solar hot water unit. Therefore, water does not have chance to flow though the collector by thermosyphon and system performance can be lowered down drastically. This thesis presents the numerical simulation study for the control and system operating parameters effects on the system performance to provide important information both for users and system designers.

Mechanical circulatory support (MCS) is a viable therapy for end stage heart failure. However, despite clinical success, the ability to compare MCS devices in vitro and perform training scenarios is extremely limited. Comparative studies are limited as different devices cannot be interchanged in a patient due to the surgical nature of implant. Further, training and failure scenarios cannot be performed on patients with devices as this would subject a patient to a failure mode. A need exists for a readily available mock system that can perform comparative testing and training scenarios with MCS devices. Previously, our group has fabricated a well characterized mock circulation system consisting of a SynCardia temporary Total Artificial Heart (TAH) and Donovan Mock Circulation tank (DMC tank). Further, utilizing this system with the TAH operating in reduced output mode, a heart failure model was developed. In the present study, three ventricular assist devices (VADs) were independently attached to the heart failure model to compare device performances over a range of preloads and afterloads. In addition, specific clinical scenarios were created with the system to analyze how VAD-displayed waveforms from the system correlate with clinical scenarios. Finally, each VAD was powered off while attached to the heart failure model to compare fluid flow through the VAD in a pump-failure scenario. We demonstrated that this system can successfully be utilized to compare MCS devices (i.e. ventricular assist devices) and for successful training of patients and clinicians.

To increase real estate values, developers often apply designs on the land. In the case of a single family housing development, the designs are applied to the unit of subdivisions. In this study, the designs are defined as “value creation concepts,” which increase housing values at the subdivision level. The value creation concepts are classified into five categories – the sense of arrival, product mix, walkability, circulation system, and amenity. This cross-sectional study focuses on exploring the effects of value creation concepts in the subdivision. Two methodologies – the Hedonic Price Model (HPM) and the Hierarchical Linear Model (HLM) – are used to test whether or not the value creation concepts would increase or decrease single family housing values. The study sample is composed of 6,562 single family houses nested in 85 subdivisions in College Station, Texas. Data are composed of two levels: the housing level and the subdivision level. The scores of the sense of arrival were provided by sixtyone graduate students at Texas A&M University using photograph evaluations. Most structural variables were obtained from the Brazos County Appraisal District, and physical environmental variables were objectively measured using the Geographical Information System. In the both models, sense of arrival, greenway connectivity, sidewalk connectivity, and median length of cul-de-sac variables have positive effects on single family housing values while phased project, the number of accessible entrances, street density, single family density, and median length of block variables have negative effects on single family housing values. At the housing level, several structural variables (e.g. bathrooms, attached garage, porches, etc), attached to a golf course, sports facilities, network distance from the nearest elementary school, population density, and personal variables (i.e., tenure, workable age, employment) were significant (p<.05) predictors of single family housing value. Findings support that the value creation concepts have effects on increasing housing values at the subdivision level, which would provide thoughtful insights for developers in residential areas. In addition, the HLM can be used as the complement of the HPM by controlling interaction terms between housing variables and subdivision variables, or among the subdivision variables themselves.