Effect of Heat Source and Imperfect Contact on Simultaneous Estimation of Thermal Properties of High-Conductivity Materials

In the current paper a novel methodology accounting for both the heater heat capacity and the imperfect thermal contact between a thin heater and a specimen is proposed. In particular, the volumetric heat capacity of the heater is considered by modelling it as a lumped capacitance body, while the imperfect thermal contact is considered by means of a contact resistance. Thus, the experimental apparatus consisting of three layers (specimen-heater-specimen) is reduced to a single finite layer (sample) subject to a "nonclassical" boundary condition at the heated surface, known as sixth kind. Once the temperature solution is derived analytically using the Laplace transform method, the scaled sensitivity coefficients are computed analytically at the interface between the heater and the sample (heater side and sample side) and at the sample backside. By applying the proposed methodology to a lab-controlled experiment available in the specialized literature, a reduction of the thermal properties values of about 1.4% is observed for a high-conductivity material (Armco iron)

A Technique for Simulating Conditions of Walking and Performing Other Self-Locomotive Activities on the Lunar Terrain

One of the most important and probably the most interesting phase of a manned lunar mission will be the time the astronauts spend outside their vehicle on the moon's surface taking scientific measurements, exploring the surface features, surveying possible sites for a lunar base, inspecting their vehicle and preparing it for their return trip. Because the lunar gravity is only one-sixth that of the earth gravity, the explorers undoubtedly will have to adjust their accustomed methods of walking, climbing, jumping and performing other self-locomotive activities in order to carry out these various tasks. In as much as the over-all success of the lunar mission will depend to a large extent upon the self-reliance of the explorers, it will be necessary to have extensive knowledge of the effects of the moon's reduced gravity on the physical capabilities of man and of man's ability to adopt to the new environment prior to the planning and execution of the mission. At the present time there is a dearth of information on this subject due primarily to the lack of a practical technique for simulating the reduced gravity. Several techniques such as immersion in water and riding in an airplane flying a Keplerian trajectory have been used for zero-g or weightlessness studies to determine the physical capabilities of man but these techniques are limited in their usefulness either by restrictions imposed by the viscous effect of the water or by the short duration and small test area available in an airplane. Consequently, an effort was made at the NASA Langley Research Center to devise a new technique that would provide a realistic simlation of a reduced gravity for unlimited periods of time and allow freedom of movement over considerable distances. This paper concerns itself with a discussion of the newly developed simulation technique and a presentation of some preliminary results which were obtained utilizing a working model based on this scheme

Conduction in rectangular plates with boundary temperatures specified

Steady-state components of heat conduction solutions may have very slowly convergent series for temperatures and non-convergent heat fluxes for temperature boundary conditions. Previous papers have proposed methods to remove these convergence problems. However, even more effective procedures based on insights of Morse and Feshbach are given herein. In some cases it is possible to replace poorly-convergent or non-convergent series by closed-form algebraic solutions. Examples are given

Pennsylvania Folklife Vol. 18, No. 3

• The End of the Horse and Buggy Era • Moravian Architecture and Town Planning: A Review • Humor in a Friendly World • Chickens and Chicken Houses in Rural Pennsylvania • Eighteenth-Century Emigrants to America from the Duchy of Zweibrucken and the Germersheim District • Horse-Drawn Transportation: Folk-Cultural Questionnaire No. 11https://digitalcommons.ursinus.edu/pafolklifemag/1035/thumbnail.jp

Solving two-dimensional Cartesian unsteady heat conduction problems for small values of the time

a b s t r a c t This paper is intended to provide very accurate analytical solutions modeling transient heat conduction processes in 2D Cartesian finite bodies for small values of the time. Analysis of diffusion of thermal deviation effects indicates that, when the space and time coordinates satisfy a criterion developed in the paper, the simple transient 1D semi-infinite solutions may be "used" for generating extremely accurate values for temperature and heat flux at any point of a finite rectangle. Also, they may be "used" with excellent accuracy as short-time solutions when the time-partitioning method is applied (so avoiding the usually difficult integration of the short-cotime Green's functions). A complex 2D semi-infinite problem is solved explicitly and evaluated numerically as part of the analysis. The proposed criterion is based on an accuracy of one part in 10 n (n ¼ 1,2,...,10,...), where n ¼ 2 is for engineering insight and visual comparison while n ¼ 10 is for verification purposes of large numerical codes

High Resolution Infrared Imaging and Spectroscopy of the Pistol Nebula: Evidence for Ejection

We present new NICMOS/HST infrared images and CGS4/UKIRT Br-alpha (4.05 um) spectroscopy of the Pistol Star and its associated nebula, finding strong evidence to support the hypothesis that the Pistol Nebula was ejected from the Pistol Star. The Pa-alpha NICMOS image shows that the nebula completely surrounds the Pistol Star, although the line intensity is much stronger on its northern and western edges. The Br-alpha spectra show the classical ring-like signature of quasi-spherical expansion, with weak blueshifted emission (V_max approx -60 km/s) and strong redshifted emission (V_max approx +10 km/s), where the velocities are with respect to the velocity of the Pistol Star; further, the redshifted emission appears to be "flattened" in the position-velocity diagram. These data suggest that the nebula was ejected from the star several thousand years ago, with a velocity between the current terminal velocity of the stellar wind (95 km/s) and the present expansion velocity of gas in the outer shell of the nebula (60 km/s). The Pa-alpha image reveals several emission-line stars in the region, including two newly-identified emission-line stars north of the Pistol Star with spectral types earlier than WC8 (T_eff > 50,000 K). The presence of these stars, the morphology of the Pa-alpha emission, and the velocity field in the gas suggest that the side of the nebula furthest from us is approaching, and being ionized by, the hot stars of the Quintuplet, and that the highest velocity redshifted gas has been decelerated by winds from the Quintuplet stars. We also discuss the possibility that the nebular gas might be magnetically confined by the ambient magnetic field delineated by the nearby nonthermal filaments.Comment: Figure 1 is included as a JPG file. Figure 1 and 2 also available at ftp://quintup.astro.ucla.edu/pistol2

Raising a Small Flock of Sheep in Ohio

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Informed Conditioning on Clinical Covariates Increases Power in Case-Control Association Studies

Genetic case-control association studies often include data on clinical covariates, such as body mass index (BMI), smoking status, or age, that may modify the underlying genetic risk of case or control samples. For example, in type 2 diabetes, odds ratios for established variants estimated from low–BMI cases are larger than those estimated from high–BMI cases. An unanswered question is how to use this information to maximize statistical power in case-control studies that ascertain individuals on the basis of phenotype (case-control ascertainment) or phenotype and clinical covariates (case-control-covariate ascertainment). While current approaches improve power in studies with random ascertainment, they often lose power under case-control ascertainment and fail to capture available power increases under case-control-covariate ascertainment. We show that an informed conditioning approach, based on the liability threshold model with parameters informed by external epidemiological information, fully accounts for disease prevalence and non-random ascertainment of phenotype as well as covariates and provides a substantial increase in power while maintaining a properly controlled false-positive rate. Our method outperforms standard case-control association tests with or without covariates, tests of gene x covariate interaction, and previously proposed tests for dealing with covariates in ascertained data, with especially large improvements in the case of case-control-covariate ascertainment. We investigate empirical case-control studies of type 2 diabetes, prostate cancer, lung cancer, breast cancer, rheumatoid arthritis, age-related macular degeneration, and end-stage kidney disease over a total of 89,726 samples. In these datasets, informed conditioning outperforms logistic regression for 115 of the 157 known associated variants investigated (P-value = 1×10−9). The improvement varied across diseases with a 16% median increase in χ2 test statistics and a commensurate increase in power. This suggests that applying our method to existing and future association studies of these diseases may identify novel disease loci