Mass-dependent Energy Research Articles

An online decision-making strategy for routing of electric vehicle fleets

As environmental awareness grow, many organizations seek to implement Electric Vehicle (EV) fleets. Nonetheless, EVs’ low driving ranges and high recharging times, and the limited Charging Stations (CS) availability make their management more challenging than conventional vehicles. The Electric Vehicle Routing Problem (E-VRP) tackles these challenges. However, many E-VRP variants drop relevant operational constraints, use overly simple models, or do not address route update solutions during operation. This work introduces a strategy to compute EV routes and update them according to observed traffic scenarios. By using an event-based EV state-space model, the strategy tracks relevant variables to account for multiple realistic elements, including nonlinear recharging function, partial recharging, mass-dependent energy consumption, maximum CS capacities, and time-dependent travel times. First, an Offline E-VRP (Off-E-VRP) variant is solved to find initial route candidates. Then, routes are periodically updated during operation according to traffic and EV state measurements by solving an Online E-VRP (On-E-VRP) variant. Genetic Algorithms (GA) are implemented to solve the problems via novel encoding and genetic operators. Finally, simulation results show that the strategy enables the fleet to fulfil its delivery duties, the pre-operation stage provides adequate initial route candidates, and the online stage can improve performance and service quality.

Synthetic superfluid chemistry with vortex-trapped quantum impurities

We explore the effect of using two-dimensional matter-wave vortices to confine an ensemble of bosonic quantum impurities. This is modelled theoretically using a mass-imbalanced homogeneous two component Gross-Pitaevskii equation where each component has independent atom numbers and equal atomic masses. By changing the mass imbalance of our system we find the shape of the vortices are deformed even at modest imbalances, leading to barrel shaped vortices; which we quantify using a multi-component variational approach. The energy of impurity carrying vortex pairs are computed, revealing a mass-dependent energy splitting. We then compute the excited states of the impurity, which we in turn use to construct `covalent bonds' for vortex pairs. Our work opens a new route to simulating synthetic chemical reactions with superfluid systems.

Quark flavor dependence of particle flow in nucleus-nucleus collisions measured by PHENIX

We present measurements of the nuclear modification factor RAA and azimuthal anisotropy v2 for electrons from charm and bottom hadron decays at mid-rapidity (|y|<0.35) and for inclusive J/ψ via the di-muon decay channel at forward-rapidity (1.2<|y|<2.2) in Au+Au collisions at sNN=200GeV. Charm and bottom decay electron RAA can be described by a T-Matrix model based on a strongly coupling QGP scenario (2πTD=4) as well as SUBATECH and DGLV models based on quark mass dependent energy loss. Finite charm and bottom decay electron v2 are observed with significances of 3.5 and 1.1 σ. The charm decay electron v2 is better described by the Langevin + viscous hydro calculation with coalescence than that without coalescence. The charm decay electron v2 is larger than inclusive J/ψv2 with a significance of 0.7 σ. These observations hint that charm quarks are dragged by the medium and hadronize via coalescence with light-flavor quarks. Complete analyses of 36 billion Au+Au collision events from RHIC 2014 and 2016 runs increase the integrated luminosity by a factor of 8 for the charm and bottom decay electron RAA measurements, by a factor of 2 for the charm and bottom decay electron v2 measurements, and by a factor of 5 for the inclusive J/ψv2 measurements.

A void growth- and coalescence-dependent anisotropic damage model for polymeric foams

We present an elastic damage constitutive model for polymeric foam based on thermodynamics framework to consider the effects of anisotropy and the growth and coalescence of cavities. The evolution equation of the proposed model describes the material behavior sustaining anisotropic and unilateral damage. To carry out finite element analysis, the material properties for various polymeric foams are applied to the proposed damage model; we thus implement the proposed damage model in the commercial finite element program as a user-defined material subroutine. In order to validate the proposed anisotropic damage model, the numerical results are compared to the results of a series of tensile and compressive tests on various polymeric foams. Additionally, we propose the failure criterion for this damage model as based on the mass-dependent energy per unit mass at failure. The developed damage model can be used for further research on damage mechanics and finite element analysis of polymeric foams in continuum mechanics.

Charm and beauty isolation from heavy flavor decay electrons in Au+Au collisions at [formula omitted] = 200 GeV at RHIC

We present a study of charm and beauty isolation based on a data-driven method with recent measurements on heavy flavor hadrons and their decay electrons in Au+Au collisions at sNN = 200 GeV at RHIC. The individual electron pT spectra, RAA and v2 distributions from charmed and beauty hadron decays are obtained. We find that the electron RAA from beauty hadron decays (RAAb→e) is suppressed in minimum bias Au+Au collisions but less suppressed compared with that from charmed hadron decays at pT > 3.5 GeV/c, which indicates that beauty quark interacts with the hot-dense medium with depositing its energy and is consistent with the mass-dependent energy loss scenario. For the first time, the non-zero electron v2 from beauty hadron decays (v2b→e) at pT > 3.0 GeV/c is observed and shows smaller elliptic flow compared with that from charmed hadron decays at pT < 4.0 GeV/c. At 2.5 GeV/c <pT < 4.5 GeV/c, v2b→e is smaller than a number-of-constituent-quark (NCQ) scaling hypothesis. This suggests that beauty quark is unlikely thermalized and too heavy to be moved in a partonic collectivity in heavy-ion collisions at the RHIC energy.

Charged particle detection with the low-cost BPW21 Si Photodiode

It has been found that the low cost commercial photodiode BPW21 (P–N Junction Diode) can be used for the detection of charged particles such as alpha particles and fission fragments. Suitability of this photodiode for fission fragments detection has been checked and mass-dependent energy calibration has also been carried out. It indicates that it can be used as a detector for charged particle detection.

A Concept Model about Allometric Scaling of Hierarchical Energy Flow through Plant Biosystems

Ecologists have long sought a general metabolic scaling law (e.g., the 3/4 power law), although the size-independent mass-special metabolic ratemay have been selected for over evolutionary time. Here, we outline four hierarchical energy processes along the path of energy flow. These processes are represented as the scaling exponents of mass-dependent energy flow (e.g., a 1/4-scaling rule for individuals and a 1/3-scaling rule for populations). Individuals and populations have evolved as the conduits of energy flow. Interestingly, the mass-dependent hierarchical energy flow can help explain the development of a tree population. Our theory highlights that mass-dependent hierarchical energy flow may act as a metabolic integrator and suggests an energetic explanation of the evolution of plant biosystems from the individual to the community level.

Planar Dirac electrons in magnetic quantum dots

In this paper, we explore the size- and mass-dependent energy spectra and the electronic correlation of two- and three-electron graphene magnetic quantum dots. It is found that only the magnetic dots with large size can well confine the electrons. For large graphene magnetic dots with massless (ultra-relativity) electrons, the energy level structures of two Dirac electrons and even the ground state spin and angular momentum of three electrons are quite different from those of the usual semiconductor quantum dots. Also we reveal that such differences are not due to the magnetic confinement but originate from the character of the Coulomb interaction of two-component electronic wavefunctions in graphene. We reveal that the increase of the mass leads to both the crossover of the energy spectrum structures from the ultra-relativity to non-relativity ones and the increasing of the crystallization. The results are helpful for the understanding of the mass and size effects and may be useful in controlling the few-electron states in graphene-based nanodevices.

Logarithmic coarsening and glassy behavior in a polymer model with mass-dependent diffusion

We present a model of polymer growth and diffusion with frustration mechanisms for density increase and with diffusion rates of Arrhenius form with mass-dependent energy barriers Gamma(m) approximately (m-1)gamma. It shows nonuniversal logarithmic coarsening involving the exponent gamma. Strong-glass behavior is found in the typical times for disappearance of all polymers up to a given length, without reference to the equilibrium states of the macroscopic system. These features are predicted by numerical simulations, scaling theories, and an analytic solution of the master equation within an independent interval approximation, which also provides the cluster size distribution.

Carbon Isotope Analyses of Semivolatile Organic Compounds in Aqueous Media Using Solid-Phase Microextraction and Isotope Ratio Monitoring GC/MS

Solid-phase microextraction (SPME) was used to facilitate the measurement of stable carbon isotope compositions (at natural abundance) of six organic compounds representing four compound classes in aqueous solution. Toluene, methylcyclohexane, hexanol, and acetic, propionic, and valeric acids were extracted from aqueous solutions with appropriate SPME phases and thermally desorbed into the split/splitless inlet of an isotope ratio monitoring gas chromatograph/mass spectrometer (irmGC/MS). Hydrophobic compounds (toluene, methylcyclohexane, hexanol) extracted by a nonpolar SPME phase were slightly (≤0.5‰) enriched in (13)C while organic acids extracted with a polar phase were depleted in (13)C to a somewhat greater degree (≤1.5‰) relative to material remaining in the aqueous phase. Isotopic fractionation was not observed to vary systematically as a function of equilibration time or solute concentration. Further, isotope fractionation did not vary consistently with the partition coefficient (K(fw)). However, both salinity and cosolvent effects, which altered the partition coefficients of the solutes, also yielded a reduction in the magnitude of isotopic fractionation (to ≤0.4‰ for the hydrocarbons, ≤0.5‰ for the organic acids). We conclude that fractionations are most likely associated with the interactions of organic compounds with the organic phase coating SPME fibers and are specifically due to mass-dependent energy shifts upon solution of each analyte into the organic phase. In addition, fractionations are also influenced by energy shifts associated with electrostatic forces acting on the analyte in the water phase during the partitioning process. The magnitude of isotopic fractionations can be minimized under conditions appropriate for the analysis of natural waters, and with careful calibration, SPME and irmGC/MS should be a valuable means for isotopic analyses for a wide range of organic constituents in aqueous samples.

Fission-Fragment Energy-Correlation Measurements for the Thermal-Neutron Fission ofPu239andPu241

Fission-fragment mass and energy distributions and mass-versus-energy correlations have been obtained for $^{239}\mathrm{Pu}$ and $^{241}\mathrm{Pu}$ thermal-neutron-induced fission. Silicon surface-barrier detectors were used in energy-correlation measurements; absolute fragment energies were obtained by means of a recently developed mass-dependent energy calibration. Average total fragment kinetic energies before neutron emission are found to be 177.7\ifmmode\pm\else\textpm\fi{}1.8 MeV for $^{239}\mathrm{Pu}$ and 179.6\ifmmode\pm\else\textpm\fi{}1.8 MeV for $^{241}\mathrm{Pu}$. Detailed experimental results are given and compared with those of other experiments. Observed fine structure in the fragment mass distribution and in the average total fragment kinetic energy as a function of mass is correlated with the energetically preferred even-even nucleon configurations in the fragments. New determinations of the root-mean-square width of the total-kinetic-energy distribution as a function of fragment mass show structure which also appears to be correlated with the energetically preferred even-even fragment configurations. Fission neutron and gamma-ray data of other experiments are used with the new fragment kinetic energies presented here to examine the total energy balance for fission for the two cases studied. A comparison of the two mass distributions shows the heavy-fragment groups almost superimposed; the light-fragment groups are separated almost uniformly by 2 amu.

Fragment Energy Correlation Measurements forCf252Spontaneous Fission andU235Thermal-Neutron Fission

Fission-fragment mass and energy distributions and mass-versus-energy correlations have been obtained for $^{252}\mathrm{Cf}$ spontaneous fission and $^{235}\mathrm{U}$ thermal-neutron-induced fission. Silicon surface-barrier detectors were used in energy correlation measurements; absolute fragment energies were obtained by means of the mass-dependent energy calibration developed recently at this laboratory. Average total fragment kinetic energies before neutron emission are found to be 186.5\ifmmode\pm\else\textpm\fi{}1.2 MeV for $^{252}\mathrm{Cf}$ and 171.9\ifmmode\pm\else\textpm\fi{}1.4 MeV for $^{235}\mathrm{U}$. Detailed experimental results are given and compared with those of other experiments. Observed fine structure in the fragment mass distribution and in the average total fragment kinetic energy as a function of mass is correlated with the energetically preferred even-even nucleon configurations in the fragments. New determinations of the root-mean-square width of the total-kinetic-energy distribution as a function of mass show structure which is also correlated with the energetically preferred even-even fragment configurations. Fission-neutron and gamma-ray data of other experiments are used with the new fragment kinetic energies presented here to examine the total energy balance for fission for the two cases studied.