5,341 research outputs found
Relaxing in foam
We investigate the mechanical response of an aqueous foam, and its relation
to the microscopic rearrangement dynamics of the bubble-packing structure. At
rest, even though the foam is coarsening, the rheology is demonstrated to be
linear. Under flow, shear-induced rearrangements compete with
coarsening-induced rearrangements. The macroscopic consequences are captured by
a novel rheological method in which a step-strain is superposed on an otherwise
steady flow
Recommended from our members
Form Accuracy Analysis of Cylindrical Parts Produced by Rapid Prototyping
Solid Freeform fabrication processes are being considered for creating fit and assembly
nature functional parts. It is extremely important that these parts are within allowable
dimensional and geometric tolerance. The part accuracy produced by rapid prototyping process
is greatly affected by the relative orientation of build and face normal directions. A systematic
method is needed to find the reliability of the created product. This paper discusses the work
done in this area and the effect of build orientation on the part form accuracy analysis of each
specified tolerance like circularity and cylindricity. Feasible build direction that can be used to
satisfy those tolerances is identified. It will help process engineer in selecting a build direction
that can satisfy a mathematical model of form tolerance.Mechanical Engineerin
Organizational Control Systems and Software Quality: A Cross-National Study.
This study explores the relationship between organizational control modes (behavior, outcome, and clan) andsoftware quality. Much of the previous work on organizational control has examined the choice of modes giventask characteristics. This research extends work in control theory by considering the impact of control modeson the increasingly critical organizational outcome of software quality. The research is set in the context ofsoftware development organizations in three of the largest software developing countries: India, Ireland, andIsrael (the 3Is). A cross sectional survey of 400 software development organizations across the 3Is will be usedto test the developed model. In addition to the theoretical contributions, the study will provide practicalimplications to support software project managers in making better organizational control choices
Recommended from our members
Multi Objective Optimisation of Build Orientation for Rapid Prototyping with Fused Deposition Modeling (FDM)
The ability to select the optimal orientation of build up is one of the critical factors since
it affects the part surface quality, accuracy, build time and part cost. Various factors to be
considered in optimisation of build orientation for FDM are build material, support material,
build up time, surface roughness and total cost. Experiments were carried out and results are
analysed for varying build orientation for primitive geometries like cylinder. An appropriate
weighting factor has been considered for various objective functions depending on the specific
requirement of the part while carrying out multi-objective optimisation. These analyses will help
process engineers to decide proper build orientation.Mechanical Engineerin
Search for quantum criticality in a ferromagnetic system UNi1-xCoxSi2
Polycrystalline samples of the isostructural alloys UNi1-xCoxSi2 (0 <= x <=
1) were studied by means of x-ray powder diffraction, magnetization, electrical
resistivity and specific heat measurements, at temperatures down to 2 K and in
magnetic fields up to 5 T. The experimental data revealed an evolution from
strongly anisotropic ferromagnetism with pronounced Kondo effect, observed for
the alloys with x < 0.98 and being gradually suppressed with rising Co-content,
to spin-glass-like states with dominant spin fluctuations, seen for the sample
with x = 0.98. Extrapolation of the value of TC(x) yields a critical
concentration xc = 1, at which the magnetic ordering entirely disappears. This
finding is in line with preliminary data collected for stoichiometric UCoSi2.Comment: to appear in Phys. Rev.
Further evidence for intra-night optical variability of radio-quiet quasars
Although well established for BL Lac objects and radio-loud quasars, the
occurrence of intra-night optical variability (INOV) in radio-quiet quasars is
still debated, primarily since only a handful of INOV events with good
statistical significance, albeit small amplitude, have been reported so far.
This has motivated us to continue intra-night optical monitoring of bona-fide
radio-quiet quasars (RQQs). Here we present the results for a sample of 11 RQQs
monitored by us on 19 nights. On 5 of these nights a given RQQ was monitored
simultaneously from two well separated observatories. In all, two clear cases
and two probable case of INOV were detected. From these data, we estimate an
INOV duty cycle of 8% for RQQs which would increase to 19% if the
`probable variable' cases are also included. Such comparatively small INOV duty
cycles for RQQs, together with the small INOV amplitudes (1%), are in
accord with the previously deduced characteristics of this phenomenon.Comment: 15 Pages, 4 Tables, 24 Figures; Accepted in BAS
Nonlinear Bubble Dynamics in a Slowly Driven Foam
Sudden topological rearrangement of neighboring bubbles in a foam occur during coarsening, and can also be induced by applied forces. Diffusing-wave spectroscopy measurements are presented of such dynamics before, during, and after an imposed shear strain. The rate of rearrangements is proportional to the strain rate, and the shape of the correlation functions shows that they are spatially and temporally uncorrelated. Macroscopic deformation is thus accomplished by a nonlinear microscopic process reminiscent of dynamics in the propagation of earthquake faults or the flow of granular media
Comparative study of the centrosymmetric and non-centrosymmetric superconducting phases of Re3W using muon-spin spectroscopy and heat capacity measurements
We compare the low-temperature electronic properties of the centrosymmetric
(CS) and non-centrosymmetric (NCS) phases of Re3W using muon-spin spectroscopy
and heat capacity measurements. The zero-field muSR results indicate that
time-reversal symmetry is preserved for both structures of Re3W.
Transverse-field muon spin rotation has been used to study the temperature
dependence of the penetration depth lambda(T) in the mixed state. For both
phases of Re3W, lambda(T) can be explained using a single-gap s-wave BCS model.
The magnetic penetration depth at zero temperature, lambda(0), is 164(7) and
418(6) nm for the centrosymmetric and the non-centrosymmetric phases of Re3W
respectively. Low-temperature specific heat data also provide evidence for an
s-wave gap-symmetry for the two phases of Re3W. Both the muSR and heat capacity
data show that the CS material has a higher Tc and a larger superconducting gap
Delta(0) at 0 K than the NCS compound. The ratio Delta(0)/kBTc indicates that
both phases of Re3W should be considered as strong-coupling superconductors.Comment: 7 pages, to appear in Physical Review
- …