3,022 research outputs found
Refinement of Techniques Metallographic Analysis of Highly Dispersed Structures
Flaws are regularly made while developing standards and technical specifications. They can come out as minor misprints, as an insufficient description of a technique. In spite the fact that the flaws are well known, it does not come to the stage of introducing changes to standards. In this paper shows that in the normative documents is necessary to clarify the requirements for metallurgical microscopes, which are used for analysis of finely-dispersed
Life Support System Considerations for Space Station
With the growing desire to initiate a Space Station program, the interest in advanced, regenerative life support systems is also increasing. This paper briefly reviews this future spacecraft and concentrates on the advanced technology in some of the key functions of life support for this application. This paper reviews the basics of life support and its importance within a space station program. It concentrates«on the impact of major requirements and discusses some of the key influences that impact the design of the system. It also projects some of the key functional areas of the life support system which are most likely to be implemented from today\u27s current technology.
The imminent availability of the Space Shuttle has rekindled interest in the longer duration space missions and permanent orbiting space platforms. Studies are underway to define missions and concept the orbiting facilities based on the capabilities available with and limitations imposed by the Space Transportation System. A work base in space is required to economically perform the long duration, complex missions of the future and to utilize the Space Shuttle in its intended role as a space truck. The term Space Station is again coming into vogue, although other titles for this program are currently in use
Influence of combined impact and cyclic loading on the overall fatigue life of forged steel, EA4T
Role of the compaction energy level on the small strain stiffness of a silty sand soil subjected to wetting and drying
The dynamic properties of a soil are routinely quantified to describe its engineering behaviour under repeated loading. While the results of previous research studies indicate that the effect of changes in suction on the dynamic response is significant, only limited research has been engaged in the assessment of post-compacted changes in suction induced by cycles of wetting and drying. In this paper, aspects related to the dynamic properties with special reference to small strain shear modulus behaviour at different compaction energy levels are described and outlined. Particular emphasis is placed on the hysteric behaviour observed (i.e. amplitude of the hysteresis loop) and its dependence on the imparted compaction energy. The results not only confirm the importance of the recent suction ratio (or CSR) in governing the mechanical response at small strain, but they also indicate that higher compaction energy levels induce smaller hysteresis loops
Magnetoelectric Effect in Ni-PZT-Ni Cylindrical Layered Composite Synthesized by Electro-deposition
The magnetoelectric (ME) coupling of cylindrical trilayered composite was
studied in this paper. The Ni-lead zirconate titanate (PZT)-Ni trilayered
cylindrical composite was synthesized by electro-deposition. The maximum ME
voltage coefficient of cylindrical ME composite is 35V/cm Oe, about three times
higher than that of the plate trilayered composite with the same raw materials
and magnetostrictive- piezoelectric phase thickness ratio. The high ME voltage
coefficient of cylindrical composite owes to the self-bound effect of circle.
Moreover, the resulting complex condition can induce a double peak in the field
dependence of ME coefficient.Comment: 11 pages, 5 figure
Coupling between magnon and ligand-field excitations in magnetoelectric Tb3Fe5O12 garnet
The spectra of far-infrared transmission in Tb3Fe5O12 magnetoelectric single
crystals have been studied in the range between 15 and 100 cm-1, in magnetic
fields up to 10 T, and for temperatures between 5 and 150 K. We attribute some
of the observed infrared-active excitations to electric-dipole transitions
between ligand-field split states of Tb3+ ions. Anticrossing between the
magnetic exchange excitation and the ligand-field transition occurs at the
temperature between 60 and 80 K. The corresponding coupling energy for this
interaction is 6 cm-1. Temperature-induced softening of the hybrid IR
excitation correlates with the increase of the static dielectric constant. We
discuss the possibility for hybrid excitations of magnons and ligand-field
states and their possible connection to the magnetoelectric effect in
Tb3Fe5O12.Comment: submitted to Phys. Rev. B on May 15th, 201
QCD corrections to the electric dipole moment of the neutron in the MSSM
We consider the QCD corrections to the electric dipole moment of the neutron
in the Minimal Supersymmetric Standard Model. We provide a master formula for
the Wilson coefficients at the low energy scale including for the first time
the mixing between the electric and chromoelectric operators and correcting
widely used previous LO estimates. We show that, because of the mixing between
the electric and chromoelectric operators, the neutralino contribution is
always strongly suppressed. We find that, in general, the effect of the QCD
corrections is to reduce the amount of CP violation generated at the high
scale. We discuss the perturbative uncertainties of the LO computation, which
are particularly large for the gluino-mediated contribution. This motivates our
Next-to-Leading order analysis. We compute for the first time the order alpha_s
corrections to the Wilson coefficients for the gluino contributions, and
recompute the two-loop anomalous dimension for the dipole operators. We show
that the large LO uncertainty disappears once NLO corrections are taken into
account.Comment: 23 pages, 5 figures, added references, corrected typo
Family Unification, Exotic States and Light Magnetic Monopoles
Models with fermions in bifundamental representations can lead naturally to
family unification as opposed to family replication. Such models typically
predict (exotic) color singlet states with fractional electric charge, and
magnetic monopoles with multiple Dirac charge. The exotics may be at the TeV
scale, and relatively light magnetic monopoles (greater than about 10^7 GeV)
can be present in the galaxy with abundance near the Parker bound. We focus on
three family SU(4)XSU(3)XSU(3) models.Comment: 37 page
Abatement of particulate-laden SO2 in tapered bubble column with internals
The performance of particulate-laden SO2 scrubbing in a modified tapered bubble column with internals is reported in this article. The presence of particles improved the particulate-laden SO2 removal efficiency to about 15% that was elucidated by the facilitated adsorptive mass transport. Experimentation revealed that nearly 100% removal efficiency of particulate-laden SO2 was achievable without any additives or pretreatment under certain operating condition of the scrubber. An empirical correlation was developed to predict the performance of the modified tapered scrubber. Experimental values fitted excellently well with the predicted values through the correlation (within ±5% deviation). The performance of the modified tapered bubble scrubber with column internals has been found to be better than a tapered bubble column without any internals
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