40,930 research outputs found
Achieving Effective Innovation Based On TRIZ Technological Evolution
Organised by: Cranfield UniversityThis paper outlines the conception of effective innovation and discusses the method to achieve it. Effective
Innovation is constrained on the path of technological evolution so that the corresponding path must be
detected before conceptual design of the product. The process of products technological evolution is a
technical developing process that the products approach to Ideal Final Result (IFR). During the process, the
sustaining innovation and disruptive innovation carry on alternately. By researching and forecasting potential
techniques using TRIZ technological evolution theory, the effective innovation can be achieved finally.Mori Seiki – The Machine Tool Compan
Destruction of the Mott Insulating Ground State of Ca_2RuO_4 by a Structural Transition
We report a first-order phase transition at T_M=357 K in single crystal
Ca_2RuO_4, an isomorph to the superconductor Sr_2RuO_4. The discontinuous
decrease in electrical resistivity signals the near destruction of the Mott
insulating phase and is triggered by a structural transition from the low
temperature orthorhombic to a high temperature tetragonal phase. The magnetic
susceptibility, which is temperature dependent but not Curie-like decreases
abruptly at TM and becomes less temperature dependent. Unlike most insulator to
metal transitions, the system is not magnetically ordered in either phase,
though the Mott insulator phase is antiferromagnetic below T_N=110 K.Comment: Accepted for publication in Phys. Rev. B (Rapid Communications
Competing Ground States in Triple-layered Sr4Ru3O10: Verging on Itinerant Ferromagnetism with Critical Fluctuations
Sr4Ru3O10 is characterized by a sharp metamagnetic transition and
ferromagnetic behavior occurring within the basal plane and along the c-axis,
respectively. Resistivity at magnetic field, B, exhibits low-frequency quantum
oscillations when B||c-axis and large magnetoresistivity accompanied by
critical fluctuations driven by the metamagnetism when B^c-axis. The complex
behavior evidenced in resistivity, magnetization and specific heat presented is
not characteristic of any obvious ground states, and points to an exotic state
that shows a delicate balance between fluctuations and order.Comment: 18 pages, 4 figure
Adsorption, Segregation and Magnetization of a Single Mn Adatom on the GaAs (110) Surface
Density functional calculations with a large unit cell have been conducted to
investigate adsorption, segregation and magnetization of Mn monomer on
GaAs(110). The Mn adatom is rather mobile along the trench on GaAs(110), with
an energy barrier of 0.56 eV. The energy barrier for segregation across the
trenches is nevertheless very high, 1.67 eV. The plots of density of states
display a wide gap in the majority spin channel, but show plenty of
metal-induced gap states in the minority spin channel. The Mn atoms might be
invisibl in scanning tunneling microscope (STM) images taken with small biases,
due to the directional p-d hybridization. For example, one will more likely see
two bright spots on Mn/GaAs(110), despite the fact that there is only one Mn
adatom in the system
Transverse momentum dependence in the perturbative calculation of pion form factor
By reanalysing transverse momentum dependence in the perturbative calculation
of pion form factor an improved expression of pion form factor which takes into
account the transverse momentum dependenc in hard scattering amplitude and
intrinsic transverse momentum dependence associated with pion wave functions is
given to leading order, which is available for momentum transfers of the order
of a few GeV as well as for . Our scheme can be extended to
evaluate the contributions to the pion form factor beyond leading order.Comment: 13 pages in LaTeX, plus 3 Postscript figure
Critical Behavior of Hadronic Fluctuations and the Effect of Final-State Randomization
The critical behaviors of quark-hadron phase transition are explored by use
of the Ising model adapted for hadron production. Various measures involving
the fluctuations of the produced hadrons in bins of various sizes are examined
with the aim of quantifying the clustering properties that are universal
features of all critical phenomena. Some of the measures involve wavelet
analysis. Two of the measures are found to exhibit the canonical power-law
behavior near the critical temperature. The effect of final-state randomization
is studied by requiring the produced particles to take random walks in the
transverse plane. It is demonstrated that for the measures considered the
dependence on the randomization process is weak. Since temperature is not a
directly measurable variable, the average hadronic density of a portion of each
event is used as the control variable that is measurable. The event-to-event
fluctuations are taken into account in the study of the dependence of the
chosen measures on that control variable. Phenomenologically verifiable
critical behaviors are found and are proposed for use as a signature of
quark-hadron phase transition in relativistic heavy-ion collisions.Comment: 17 pages (Latex) + 24 figures (ps file), submitted to Phys. Rev.
Coherent exciton dynamics in the presence of underdamped vibrations
Recent ultrafast optical experiments show that excitons in large biological
light-harvesting complexes are coupled to molecular vibration modes. These
high-frequency vibrations will not only affect the optical response, but also
drive the exciton transport. Here, using a model dimer system, the frequency of
the underdamped vibration is shown to have a strong effect on the exciton
dynamics such that quantum coherent oscillations in the system can be present
even in the case of strong noise. Two mechanisms are identified to be
responsible for the enhanced transport efficiency: critical damping due to the
tunable effective strength of the coupling to the bath, and resonance coupling
where the vibrational frequency coincides with the energy gap in the system.
The interplay of these two mechanisms determines parameters responsible for the
most efficient transport, and these optimal control parameters are comparable
to those in realistic light-harvesting complexes. Interestingly, oscillations
in the excitonic coherence at resonance are suppressed in comparison to the
case of an off-resonant vibration
Evolution of Magnetism in Single-Crystal Honeycomb Iridates
We report the successful synthesis of single-crystals of the layered iridate,
(NaLi)IrO, , and a thorough study of
its structural, magnetic, thermal and transport properties. The new compound
allows a controlled interpolation between NaIrO and LiIrO,
while maintaing the novel quantum magnetism of the honeycomb Ir planes.
The measured phase diagram demonstrates a dramatic suppression of the N\'eel
temperature, , at intermediate suggesting that the magnetic order in
NaIrO and LiIrO are distinct, and that at , the
compound is close to a magnetically disordered phase that has been sought after
in NaIrO and LiIrO. By analyzing our magnetic data with a
simple theoretical model we also show that the trigonal splitting, on the
Ir ions changes sign from NaIrO and LiIrO, and the
honeycomb iridates are in the strong spin-orbit coupling regime, controlled by
\jeff=1/2 moments.Comment: updated version with more dat
Fluctuations of Spatial Patterns as a Measure of Classical Chaos
In problems where the temporal evolution of a nonlinear system cannot be
followed, a method for studying the fluctuations of spatial patterns has been
developed. That method is applied to well-known problems in deterministic chaos
(the logistic map and the Lorenz model) to check its effectiveness in
characterizing the dynamical behaviors. It is found that the indices
are as useful as the Lyapunov exponents in providing a quantitative measure of
chaos.Comment: 10 pages + 7 figures (in ps file), LaTex, Submitted to Phys. Rev.
High-temperature weak ferromagnetism on the verge of a metallic state: Impact of dilute Sr-doping on BaIrO3
The 5d-electron based BaIrO3 is a nonmetallic weak ferromagnet with a Curie
temperature at Tc=175 K. Its largely extended orbitals generate strong
electron-lattice coupling, and magnetism and electronic structure are thus
critically linked to the lattice degree of freedom. Here we report results of
our transport and magnetic study on slightly Sr doped BaIrO3. It is found that
dilute Sr-doping drastically suppresses Tc, and instantaneously leads to a
nonmetal-metal transition at high temperatures. All results highlight the
instability of the ground state and the subtle relation between magnetic
ordering and electron mobility. It is clear that BaIrO3 along with very few
other systems represents a class of materials where the magnetic and transport
properties can effectively be tuned by slight alterations in lattice
parameters
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