Computation for a Three by Three Array of Protrusions Cooled by Liquid Immersion: Effect of Substrate Thermal Conductivity

A computational study of natural convection in an enclosure as applied to applications in cooling of electronic components is reported. The investigation is for a configuration consisting of a three by three array of heated protrusions placed on a vertical substrate. The vertical sidewalls are all insulated, and the top and bottom walls serve as isothermal heat sinks. A thin layer at the back of each protrusion is the heat source, where heat is generated uniformly and volumetrically. The coolant is the flourinert liquid FC75. The code was first validated with experimental results reported earlier on the same configuration. The effect of the substrate conductivity, κs on the heat transfer and fluid flow was then studied for power levels of 0.1 and 0.7 Watts per protrusion. The computations indicate that the effect of increasing κs is dramatic. The protrusion temperatures which were found to be nominally steady, were substantially reduced. The percentage of generated power that is directly conducted to the substrate increased with an increase in κs . The fluid velocity field, which was unsteady, was not significantly affected by changes in κs .Naval Surface Warfare CenterSHAR

Computation for a Three by Three Array of Protrusions Cooled by Liquid Immersion: Effect of Substrate Thermal Conductivity

A computational study of natural convection in an enclosure as applied to applications in cooling of electronic components is reported. The investigation is for a configuration consisting of a three by three array of heated protrusions placed on a vertical substrate. The vertical sidewalls are all insulated, and the top and bottom walls serve as isothermal heat sinks. A thin layer at the back of each protrusion is the heat source, where heat is generated uniformly and volumetrically. The coolant is the flourinert liquid FC75. The code was first validated with experimental results reported earlier on the same configuration. The effect of the substrate conductivity, κs on the heat transfer and fluid flow was then studied for power levels of 0.1 and 0.7 Watts per protrusion. The computations indicate that the effect of increasing κs is dramatic. The protrusion temperatures which were found to be nominally steady, were substantially reduced. The percentage of generated power that is directly conducted to the substrate increased with an increase in κs . The fluid velocity field, which was unsteady, was not significantly affected by changes in κs .Naval Surface Warfare CenterSHAR

Housing and Child Health: Safety Net Strategies, Regulations and Neighborhood Challenges

Abstract: “Improving Neighborhoods: An Innovative Program of Hospital-Community Collaboration” Although often overlooked as a key factor in health status, stable and affordable housing plays a critical role in protecting children and adolescents. This article examines possibilities as well as challenges in health-oriented housing interventions for children, with particular attention to understanding how the law—and its limits—shape the nature of non-profit housing work. First, the authors discuss the scholarly literature on the relationship between health and housing to consider why healthcare institutions generally and children’s hospitals specifically might enter into the challenging fray of housing advocacy for the poor. They then discuss the history and motivational basis of one initiative undertaken by a children’s hospital to increase housing stock and stability—the Healthy Homes (HH) initiative sponsored by Nationwide Children’s Hospital in Columbus, Ohio. Focusing on the “nuts and bolts” of such programs, the authors discuss what hospitals must do to actualize such a program. They examine the key mechanisms that the Hospital and its partners have found to be critical to acquiring, building and rehabilitating, and ultimately getting new owners into stable, high-quality homes. They also examine the community relationships and intricacies for the success of the project. The basis for this research includes a series of interviews with key stakeholders, a walking tour of the primary neighborhood impacted by the neighborhood, as well as analysis of HH-related web sites and relevant scholarly literatures. Ultimately, the article examines HH to offer general guidance that other children’s hospitals might use to engage their own programs. Along the way the article catalogs best practices and lessons learned, both within existing legal mechanisms and more informally

Mid-holocene climate change and landscape formation in ireland: evidence from a geochemical investigation of a coastal peat bog

Following a period of unusually strong winds and high seas in the spring of 2014, a blanket peat bog formerly covered by a beach comprised of fine sand and large rocks was uncovered at a coastal site in Spiddal, Co. Galway, Ireland. The surface of the bog was littered with standing tree stumps, the remnants of a Holocene forest that had succumbed to a relatively sudden drowning. A combination of inorganic and organic geochemical techniques was applied to determine the cause of this rapid submersion and to glean palaeoclimatic information from the preserved record within the peat. The study represents the first use of a multiproxy lipid biomarker approach to investigate palaeoclimate conditions from a peat bog in Ireland. The results provide evidence of climatic variation throughout a ca. 3400 yr timeframe during the mid-Holocene. Biomarker proxies displaying the relative contribution of Sphagnum spp. vs. higher plants were used to show changes in precipitation and temperature during peat formation. The data correlate with described events, including the 4.2 ka event and the Subboreal-Subatlantic transition and show the benefit of a lipid biomarker method for investigating Ireland’s peatland resources. In particular, the indication of colder/wetter conditions coinciding with the 4.2 ka event implies the possibility that its effects were felt in Ireland, contrary to some reports. The results suggest that a combination of warm and dry conditions followed by a rapid rise in sea level led to the growth and subsequent drowning of the ancient forest landscape

Effect of wall conduction on natural convection over a vertical slender hollow circular cylinder

An analysis is made of the laminar natural convection of incompressible fluids over a slender, hollow circular cylinder with the inner surface at a constant temperature of T b . The temperature of the outer surface must be solved from the coupled conduction of the cylinder and the natural convection of the fluid over the cylinder. The objective of this paper is to investigate the effect of conduction on the heat transfer characteristics of the natural convection boundary layer of the fluid. A wall conduction parameter, p , is introduced which is a measure of the heat conductivities of the solid and the fluid and the thickness of the cylindrical shell. The governing differential equations, being non-similar, are solved by a finite-difference method. Numerical results are generated for a series of values of p 's and Prandtl numbers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41805/1/10494_2005_Article_BF01666801.pd