The mechanical design of a vapor compressor for a heat pump to be used in space

A heat pump developed for use in Spacelab as a stand-alone refrigeration unit as well as within a fluid loop system is discussed. It will provide an active thermal control for payloads. Specifications for the heat pump were established: (1) heat removal rates at the source; (2) heat source temperatures from room temperature; (3) heat-sink fluid temperatures at condenser inlet; and (4) minimum power consumption. A reversed Carnot cycle heat pump using Freon 12 as working fluid incorporating a one-cylinder reciprocating compressor was selected. The maximum crankshaft speed was fixed relatively high at 100 rpm. The specified cooling rates then made it necessary to select a cylinder volume of 10 cu cm, which was obtained with a bore of 40 mm and a stroke of 8 mm

Homiletics: Studies on the Old Testament Texts

Studies on the Old Testament Text

Estimating Total Cost of Ownership for United States Air Force Chiller Assets

In order to make the most cost-effective choice when purchasing high-value assets, organizations must be able to quantify and compare the costs associated with acquiring, maintaining and disposing the alternatives. Currently, the United States Air Force (USAF) Civil Engineer (CE) enterprise has no standardized model to accurately and efficiently predict the total cost of ownership (TCO) for the acquisition of new assets. As such, acquisition efforts throughout the enterprise are disjointed and performed without leveraging the considerable buying power wielded by an organization as large as the USAF. This research developed a TCO model using a standard, dollar-based approach that combined linear additive and regression modeling techniques. The model was derived from existing operations and maintenance and contract spending data associated with heating, ventilation, and air conditioning. The TCO model provides USAF acquisition, contracting, and civil engineering professionals a tool with which to project life-cycle costs, negotiate prices, and justify spending decisions. Furthermore, the model provides a proof of concept to the CE enterprise that will allow for the expansion of TCO modeling to other categories of spending

Activities and Classroom Demonstrations in Biological Physics: A resource document

We give detailed recipes for a number of classroom demonstrations relevant to biological physics instruction. We developed them mainly for use in 2nd-3rd year undergraduate Physics courses. But you can (and we do) use them for primary school, through high school, up to PhD candidates. You adapt the words for each audience, but a phenomenon is a phenomenon. We also outline a 1-hour introduction to Python for undergraduate scientific computing. Finally we document some outcomes from courses taught at U Pennsylvania using these resources and others cited here. This material was presented at a workshop at the AAPT meeting in July 2018

Animal-Sediment Relationships and Early Sediment Diagenesis in Long Island Sound

Guidebook for field trips in Connecticut: New England Intercollegiate Geological Conference 60th annual meeting, Yale University, New Haven, Connecticut, October 25-27, 1968: Trip E-

Large-eddy simulation of mesoscale dynamics and entrainment around a pocket of open cells observed in VOCALS-REx RF06

Large-eddy simulations of a pocket of open cells (POC) based on VOCALS Regional Experiment (REx) NSF C-130 Research Flight 06 are analyzed and compared with aircraft observations. A doubly-periodic domain 192 km × 24 km with 125 m horizontal and 5 m vertical grid spacing near the capping inversion is used. The POC is realized in the model as a fixed 96 km wide region of reduced cloud droplet number concentration (<i>N</i><sub>c</sub>) based on observed values; initialization and forcing are otherwise uniform across the domain. The model reproduces aircraft-observed differences in boundary-layer structure and precipitation organization between a well-mixed overcast region and a decoupled POC with open-cell precipitating cumuli, although the simulated cloud cover is too large in the POC. A sensitivity study in which <i>N</i><sub>c</sub> is allowed to advect following the turbulent flow gives nearly identical results over the 16 h length of the simulation (which starts at night and goes into the next afternoon). <br><br> The simulated entrainment rate is nearly a factor of two smaller in the less turbulent POC than in the more turbulent overcast region. However, the inversion rises at a nearly uniform rate across the domain because powerful buoyancy restoring forces counteract horizontal inversion height gradients. A secondary circulation develops in the model that diverts subsiding free-tropospheric air away from the POC into the surrounding overcast region, counterbalancing the weaker entrainment in the POC with locally weaker subsidence

Understanding and optimising the packing density of perylene bisimide layers on CVD-grown graphene

The non-covalent functionalisation of graphene is an attractive strategy to alter the surface chemistry of graphene without damaging its superior electrical and mechanical properties. Using the facile method of aqueous-phase functionalisation on large-scale CVD-grown graphene, we investigated the formation of different packing densities in self-assembled monolayers (SAMs) of perylene bisimide derivatives and related this to the amount of substrate contamination. We were able to directly observe wet-chemically deposited SAMs in scanning tunnelling microscopy (STM) on transferred CVD graphene and revealed that the densely packed perylene ad-layers adsorb with the conjugated {\pi}-system of the core perpendicular to the graphene substrate. This elucidation of the non-covalent functionalisation of graphene has major implications on controlling its surface chemistry and opens new pathways for adaptable functionalisation in ambient conditions and on the large scale.Comment: 27 pages (including SI), 10 figure

A Demonstration of the Infrared Activity of Carbon Dioxide

Before they can talk meaningfully about anthropogenic climate change, students need to grasp basic principles of natural planetary climates, for example, the key role of trace atmospheric gases in setting surface temperature. We describe a dramatic demonstration that scales well for large audiences and that requires as little as ten classroom minutes to show the crucial difference between room air and carbon dioxide gas. Beyond its significance for public policy, the demonstration can serve as a springboard to motivate discussion of important physics concepts such as rotation and vibration spectra