Radiation Effects on Shear Strength of Several Alloys at Liquid Hydrogen Environment

This paper studies the effects of radiative heat transfer on the thermal characteristics of regeneratively cooled rocket engines. A conjugated radiative, conductive and convective model is used to analyze the effects of radiative heat transfer in two regeneratively cooled rocket engines. One engine has liquid hydrogen and liquid oxygen as the propellant and liquid hydrogen as the coolant. The other engine has RP1 (a hydrocarbon fuel) and liquid oxygen as the propellant and liquid oxygen as the coolant. It is shown that gas radiation has some effect on the wall temperature of the LH2-LO2 engine and a small effect on its coolant flow characteristics. For the RP1-LO2 engine, however, gas radiation significantly increases the coolant pressure drop, temperature and Mach number. It is also shown that radiation effects must be addressed in cooling channel design, so that wall temperatures and cryogenic coolant flow temperature/pressure are at suitable levels.

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Quantitative analysis of in situ straining experiments in the case of strong frictional forces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109999 ◽

1978 ◽

Vol 36 (1) ◽

pp. 570-571

Author(s):

F. Louchet ◽

L.P. Kubin

Keyword(s):

Strain Rate ◽

Radiation Effects ◽

Dislocation Line ◽

Critical Length ◽

Local Strain ◽

Local Flow ◽

Double Kink ◽

Dislocation Densities ◽

Frictional Forces ◽

Local Strain Rate

Investigation of frictional forces -Experimental techniques and working conditions in the high voltage electron microscope have already been described (1). Care has been taken in order to minimize both surface and radiation effects under deformation conditions.Dislocation densities and velocities are measured on the records of the deformation. It can be noticed that mobile dislocation densities can be far below the total dislocation density in the operative system. The local strain-rate can be deduced from these measurements. The local flow stresses are deduced from the curvature radii of the dislocations when the local strain-rate reaches the values of ∿ 10-4 s-1.For a straight screw segment of length L moving by double-kink nucleation between two pinning points, the velocity is :where ΔG(τ) is the activation energy and lc the critical length for double-kink nucleation. The term L/lc takes into account the number of simultaneous attempts for double-kink nucleation on the dislocation line.

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Beam-radiation effects on wool in the ESEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100144760 ◽

1986 ◽

Vol 44 ◽

pp. 674-675

Author(s):

G.D. Danilatos

Keyword(s):

Electron Beam ◽

Radiation Effects ◽

Research Work ◽

Beam Radiation ◽

Liquid Environment ◽

Know How ◽

Environmental Sem

The advent of the environmental SEM (ESEM) has made possible the examination of uncoated and untreated specimen surfaces in the presence of a gaseous or liquid environment. However, the question arises as to what degree the examined surface remains unaffected by the action of the electron beam. It is reasonable to assume that the beam invariably affects all specimens but the type and degree of effect may be totally unimportant for one class of applications and totally unacceptable for another; yet, for a third class, it is imperative to know how our observations are modified by the presence of the beam. The aim of this report is to create an awareness of the need to initiate research work in various fields in order to determine the guiding rules of the limitations (or even advantages) due to irradiation.

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New Insulators, Devices and Radiation Effects

10.1016/s1874-5903(99)x8001-3 ◽

1999 ◽

Keyword(s):

Radiation Effects

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Strahlenwirkung am Normalgewebe

Nuklearmedizin ◽

10.1055/s-0038-1626537 ◽

2010 ◽

Vol 49 (S 01) ◽

pp. S53-S58 ◽

Cited By ~ 1

Author(s):

W. Dörr

Keyword(s):

Radiation Exposure ◽

Normal Tissue ◽

Radiation Effects ◽

A Priori ◽

Cell Loss ◽

Turnover Time ◽

Complete Healing ◽

Internal Radiotherapy ◽

Normal Tissues ◽

Chronic Radiation

SummaryThe curative effectivity of external or internal radiotherapy necessitates exposure of normal tissues with significant radiation doses, and hence must be associated with an accepted rate of side effects. These complications can not a priori be considered as an indication of a too aggressive therapy. Based on the time of first diagnosis, early (acute) and late (chronic) radiation sequelae in normal tissues can be distinguished. Early reactions per definition occur within 90 days after onset of the radiation exposure. They are based on impairment of cell production in turnover tissues, which in face of ongoing cell loss results in hypoplasia and eventually a complete loss of functional cells. The latent time is largely independent of dose and is defined by tissue biology (turnover time). Usually, complete healing of early reactions is observed. Late radiation effects can occur after symptom-free latent times of months to many years, with an inverse dependence of latency on dose. Late normal tissue changes are progressive and usually irreversible. They are based on a complex interaction of damage to various cell populations (organ parenchyma, connective tissue, capillaries), with a contribution from macrophages. Late effects are sensitive for a reduction in dose rate (recovery effects).A number of biologically based strategies for protection of normal tissues or for amelioration of radiation effects was and still is tested in experimental systems, yet, only a small fraction of these approaches has so far been introduced into clinical studies. One advantage of most of the methods is that they may be effective even if the treatment starts way after the end of radiation exposure. For a clinical exploitation, hence, the availability of early indicators for the progression of subclinical damage in the individual patient would be desirable. Moreover, there is need to further investigate the molecular pathogenesis of normal tissue effects in more detail, in order to optimise biology based preventive strategies, as well as to identify the precise mechanisms of already tested approaches (e. g. stem cells).

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Holding Power of Orthopaedic Screws in Metacarpal and Metatarsal Bones of Young Calves

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0038-1633077 ◽

1992 ◽

Vol 05 (03) ◽

pp. 100-103 ◽

Cited By ~ 4

Author(s):

G. Jean ◽

J. K. Roush ◽

R. M. DeBowes ◽

E. M. Gaughan ◽

J. Kirpensteijn

Keyword(s):

Shear Strength ◽

Tensile Load ◽

Young Female ◽

Limiting Factor ◽

Holding Power ◽

Metatarsal Bones ◽

Bone Width ◽

Load To Failure ◽

Holstein Calves

SummaryThe holding power and holding power per mm bone width of 4.5 mm and 5.5 mm cortical and 6.5 mm cancellous orthopaedic screws were obtained by tensile load-to-failure studies in excised metacarpal and metatarsal bones of young female Holstein calves. Holding power and holding power per mm bone width of 6.5 mm orthopaedic screws were significantly greater than those of 4.5 and 5.5 mm orthopaedic screws in the diaphysis and metaphysis. Significant differences were not detected between holding power and holding power per mm bone width of 4.5 and 5.5 mm orthopaedic screws. The holding power was not different between metacarpi and metatarsi. The limiting factor in all tests of holding power was the shear strength of the bone. We found that 6.5 mm orthopaedic screws have the greatest holding power in the metacarpal and metatarsal bones of young calves.This study compares the holding power of 4.5 mm and 5.5 mm cortical and 6.5 mm cancellous orthopaedic screws in excised metacarpal and metatarsal bones from young female Holstein calves. We found that 6.5 mm orthopaedic screws have the greatest holding power.

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