422 research outputs found
A New Hybrid Power Configuration In HEV and Its Driving BLDC Development
Hybrid electric vehicle (HEV) that has the advantages of high performance, high fuel efficiency, low emission, and long operating range is focused on nowadays. A new hybrid power configuration used in HEV is presented with different control strategies and HEV performances when equipping different weight of fuel power and battery one. In order to realize the new hybrid power configuration especially in the refitted HEV, fractional-slot concentrated-winding BLDC with higher rated spinning speed is given and the prototyped one is developed and fabricated which satisfies successfully the requirements of high performance and demission restriction for the refitted HEV
Smooth Flow in Diamond: Atomistic Ductility and Electronic Conductivity
Diamond is the quintessential superhard material widely known for its stiff and brittle nature and large electronic band gap. In stark contrast to these established benchmarks, our first-principles studies unveil surprising intrinsic structural ductility and electronic conductivity in diamond under coexisting large shear and compressive strains. These complex loading conditions impede brittle fracture modes and promote atomistic ductility, triggering rare smooth plastic flow in the normally rigid diamond crystal. This extraordinary structural change induces a concomitant band gap closure, enabling smooth charge flow in deformation created conducting channels. These startling soft-and-conducting modes reveal unprecedented fundamental characteristics of diamond, with profound implications for elucidating and predicting diamond’s anomalous behaviors at extreme conditions
Computational Discovery of A New Rhombohedral Diamond Phase
We identify by first-principles calculations a new diamond phase in R¯3c (D63d) symmetry, which has a 16-atom rhombohedral primitive cell, thus termed R16 carbon. This rhombohedral diamond comprises a characteristic all-sp3 six-membered-ring bonding network, and it is energetically more stable than previously identified diamondlike six-membered-ring bonded BC8 and BC12 carbon phases. A phonon mode analysis verifies the dynamic structural stability of R16 carbon, and electronic band calculations reveal that it is an insulator with a direct band gap of 4.45 eV. Simulated x-ray diffraction patterns provide an excellent match to recently reported distinct diffraction peaks found in milled fullerene soot, suggesting a viable experimental synthesis route. These findings pave the way for further exploration of this new diamond phase and its outstanding properties
First-principles Study of High-Pressure Phase Stability and Superconductivity of Bi4I4
Bismuth iodide Bi4I4 exhibits intricate crystal structures and topological insulating states that are highly susceptible to influence by environments, making its physical properties highly tunable by external conditions. In this work, we study the evolution of structural and electronic properties of Bi4I4 at high pressure using an advanced structure search method in conjunction with first-principles calculations. Our results indicate that the most stable ambient-pressure monoclinic α−Bi4I4 phase in C2/m symmetry transforms to a trigonal P31c structure (ɛ−Bi4I4) at 8.4 GPa, then to a tetragonal P4/mmm structure (ζ−Bi4I4) above 16.6 GPa. In contrast to the semiconducting nature of ambient-pressure Bi4I4, the two high-pressure phases are metallic, in agreement with reported electrical measurements. The ɛ−Bi4I4 phase exhibits distinct ionic states of Iδ− and (Bi4I3)δ + (δ=0.4123 e), driven by a pressure-induced volume reduction. We show that both ɛ- and ζ−Bi4I4 are superconductors, and the emergence of pressure-induced superconductivity might be intimately linked to the underlying structural phase transitions
A LONGITUDINAL ANALYSIS OF CENTER OF PRESSURE IN PREGNANT GAIT THROUGHOUT PREGNANCY AND POST-PARTUM
The changes of physiological and morphological during pregnancy muld lead to gait pattern's changes. The aim of this study was to analysis the variation of pregnancy gait balance. Sixteen healthy pregnant women by choosing were performed during the second and third trimesters and again post-partum. Novel EMED was used for measuring the trajectory of the centre of pressure (COP). The results revealed that COP deviation distance (Dn) significantly increase in third trimester compared with post-partum during the initial contact phase (P=0.038). No differences were observed in the deviation distance of trimesters and postpartum during the forefoot push off phase. This method and results maybe have a new sight to reveal the dynamic stability with advanced pregnancy
Effect of Temperature on the Corrosion Behaviours of L360QCS in the Environments Containing Elemental Sulphur and H₂S/CO₂
The effect of temperature on the corrosion behaviours of L360QCS in H₂S, CO₂ and elemental sulphur environments are investigated. The corrosion weight-loss rate, microscopy, chemical compositions and phase compositions of corrosion products are studied by means of the weight-loss analysis, SEM and XRD techniques. As shown, the corrosion rate increased greatly with an increase of the temperature, and the corrosion scale is dropped off easily because of the weak adhesion force between the matrix and the corrosion products. The composition and structure analysed by energy-dispersive x-ray spectroscopy (EDS) and XRD show that the corrosion product scales are composed of cubic FeS and little tetragonal FeS.Исследовано влияние температуры на режимы коррозии L360QCS в атмосферах H₂S, CO₂ и атомарной серы. Скорость коррозии, измеряемая по потере веса, микроскопия, химический и фазовый состав продуктов коррозии определялись анализом потери веса, СЭМ и рентгеноструктурным анализом (РСА). Показано, что скорость коррозии сильно возрастает с температурой, и коррозионная окалина легко отпадает благодаря слабой силе адгезии между матрицей и продуктами коррозии. Исследования состава и структуры методами рентгеноспектрального электронно-зондового микроанализа и РСА показали, что окалины продуктов реакции состоят из кубического FeS и небольшой части тетрагонального FeS.Досліджено вплив температури на режими корозії L360QCS в атмосфері H₂S, CO₂ та атомарної сірки. Швидкість корозії, яка вимірюється за втратами ваги, мікроскопія, хемічний та фазовий склад продуктів корозії визначалися аналізою втрати ваги, СЕМ та рентґеноструктурною аналізою (РСА). Показано, що швидкість корозії сильно збільшується з температурою, і корозійна жужелиця легко відпадає через слабку силу адгезії між матрицею та продуктами корозії. Дослідження складу та структури методами рентґеноспектральної електронно-зондової мікроаналізи та РСА показали, що жужелиці продуктів реакції складаються з кубічного FeS та незначної частки тетрагонального FeS
Cumulants of net-strangeness multiplicity distributions at energies available at the BNL Relativistic Heavy Ion Collider
The higher-order cumulants of net-proton number, net-charge, and
net-strangeness multiplicity distributions are widely studied to search for the
quantum-chromodynamics critical point and extract the chemical freeze-out
parameters in heavy-ion collisions. In this context, the event-by-event
fluctuations of the net-strangeness multiplicity distributions play important
roles in extracting the chemical freeze-out parameter in the strangeness
sector. Due to having difficulties in detecting all strange hadrons event by
event, the kaon () and lambda () particles serve as a proxy for the
strangeness-related observables in heavy-ion collisions. We have studied the
net-, net-, and net-( + ) multiplicity distributions
and calculated their different order of cumulants using the ultrarelativistic
quantum molecular dynamics model and hadron resonance gas calculation. To
adequately account for the net-strangeness cumulants, it has been found that
the inclusion of resonance decay contributions in and is
necessary.Comment: The title has been modified. Updated following the published versio
On Beckner's Inequality for Axially Symmetric Functions on
We prove that axially symmetric solutions to the -curvature type problem
\alpha P_6 u + 120(1-\frac{e^{6u}}{\int_{\mathbb{S}^6} e^{6u}})=0 \ \ \ \ \
\mbox{on} \ \mathbb{S}^6 must be constants, provided that . In view of the existence of non-constant solutions obtained by
Gui-Hu-Xie \cite{GHW2022} for , this result is
sharp. This result closes the gap of the related results in \cite{GHW2022},
which proved a similar uniqueness result for . The
improvement is based on two types of new estimates: one is a better estimate of
the semi-norm , the other one is a family of refined
estimates on Gegenbauer coefficients, such as pointwise decaying and
cancellations properties.Comment: 31 pages; any comment is welcom
Rigidity results on Liouville equation
We give a complete classification of solutions bounded from above of the
Liouville equation -\Delta u=e^{2u}\quad\mbox{in}\quad {\mathbf{R}}^2. More
generally, solutions in the class are described. As a consequence, we obtain five
rigidity results. First, can take only a discrete set of values: either
, or is a non-negative integer. Second, as
, if and only if is radial about some point. Third, if is
symmetric with respect to and axes and in the first
quadrant then is radially symmetric. Fourth, if is concave and bounded
from above, then is one-dimensional. Fifth, if is bounded from above,
and the diameter of with the metric is ,
where is the Euclidean metric, then is either radial about a point
or one-dimensional.
In addition, we extend the concavity rigidity result on Liouville equation in
higher dimensions.Comment: 14 page
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