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In vendor managed inventory (VMI) operations, it is necessary for both the suppliers and the customers to reach an agreement on the maximal and minimal inventory level. In practice, in VMI, inventory levels are decided manually by planning personnel, based on their experience and past operating records. From a system optimization point of view, the determination of the upper and lower inventory levels in storage areas is complicated, necessitating analysis of many factors. Consequently, it may not be possible to obtain the best planning results, to determine and maintain the optimum levels of inventory. In this study, we utilize network flow techniques to build a replenishment model to deal with the upper-and-lower inventory level control problem, with the objective of minimizing the total cost in short-term operations, subject to inventory level control and other operating constraints. The model is formulated as an integer network flow problem with side constraints and is characterized as NP-hard in terms of optimization. To efficiently and effectively solve the large-scale problems that occur in the real world, a solution algorithm is also developed. Finally, numerical tests are conducted using real data from a major retail company in northern Taiwan. The results demonstrate the usefulness of the proposed model and solution algorithm for replenishment planning in actual practice.

The associated magnetic moments of the periodic rotational motion of methyl groups in hexamethylbenzene C$_6$(CH$_3$)$_6$ were recently identified to contribute to its overall magnetic susceptibility. Those measurements however, were only performed on hydrogenous polycrystalline samples. We report magnetic susceptibility measurements on single crystalline C$_6$(CH$_3$)$_6$ in the cases where the applied magnetic field is parallel and perpendicular to the molecular basal planes. In the former case, metastable behavior near the onset temperature T$_{C-H}$=118 K is identified while in the latter, no anomalous behavior is observed. Similar anomalies are observed in deuterated hexamethylbenzene C$_6$(CD$_3$)$_6$ (where D is deuterium), however, T$_{C-D}$ occurs 14 K higher at 132 K. In addition, a peak anomaly identified near 42 K is suggested to be due to the onset of coherent quantum tunneling of deuterons. The near cubic ground state is proposed to be the result of a more radical form of the Jahn-Teller effect occurring in a molecular solid where the lattice distorts to remove the orbital degeneracies of the protons to lower its energy. The apparent magnetic anisotropy and isotope effect provide evidence that apart from electrons, not only protons, but also deuterons establish strongly correlated behavior., Comment: 21 pages (double spaced), 4 figures + 2 supplementary figures, Just Accepted Manuscript by the Journal of Physical Chemistry C

The types of magnetism known to date are all mainly based on contributions from electron motion. We show how rotational motion of protons (H+) within the methyl groups in hexamethylbenzene (C6(CH3)6) also contribute significantly to the magnetic susceptibility. Starting from below 118 K, as the rotational motion of the methyl groups set in, an associated magnetic moment positive in nature due to charge of the protons renders the susceptibility to become anomalously dependent on temperature. Starting from 20 K, the susceptibility diverges with decreasing temperature indicative of spin–spin interactions between methyl groups aligned in a previously unclassified type of anti-ferromagnetic configuration. Complementary dielectric constant measurements also show the existence of magneto-dielectric coupling. Our findings allow for the study of strongly correlated systems that are based on a species that possesses much slower dynamics.

A linear induction motor system composed of a high– T c superconducting secondary with close-ended coils made of REBCO coated conductor wire was designed and tested experimentally. The measured thrust, normal force and power loss are presented and explained by combining the flux dynamics inside superconductors with existing linear drive theory. It is found that an inherent capacitive component associated to the flux motion of vortices in the Type-II superconductor reduces the impedance of the coils; from such, the associated Lorentz forces are drastically increased. The resulting breakout thrust of the designed linear motor system was found to be extremely high (up to 4.7 kN/m 2 ) while the associated normal forces only a fraction of the thrust. Compared to its conventional counterparts, high- T c superconducting secondaries appear to be more feasible for use in maglev propulsion and electromagnetic launchers.

Epitaxy and misfit strain imposed by underlying substrates have been intensively used to tailor the microstructure and electronic properties of oxide films, but this approach is largely restricted by commercially limited substrates. In contrast to the conventional epitaxial misfit strains with a positive Poisson’s constant, we show here a tunable Poisson’s ratio with anomalous values from negative, zero, to positive. This permits effective control over the out-of-plane lattice parameters that strongly correlate the magnetic and transport properties in perovskite mixed-valence La1–xSrxMnO3 thin films. Our results provide an unconventional approach to better modulation and understanding of elastic-mediated microstructures and physical properties of oxide films by engineering the Poisson’s ratios.

As a follow-up of our previous work on pressure-induced metallization of the 2H_{c}-MoS_{2} [Chi et al., Phys. Rev. Lett. 113, 036802 (2014)PRLTAO0031-900710.1103/PhysRevLett.113.036802], here we extend pressure beyond the megabar range to seek after superconductivity via electrical transport measurements. We found that superconductivity emerges in the 2H_{a}-MoS_{2} with an onset critical temperature T_{c} of ca. 3 K at ca. 90 GPa. Upon further increasing the pressure, T_{c} is rapidly enhanced beyond 10 K and stabilized at ca. 12 K over a wide pressure range up to 220 GPa. Synchrotron x-ray diffraction measurements evidenced no further structural phase transition, decomposition, and amorphization up to 155 GPa, implying an intrinsic superconductivity in the 2H_{a}-MoS_{2}. DFT calculations suggest that the emergence of pressure-induced superconductivity is intimately linked to the emergence of a new flat Fermi pocket in the electronic structure. Our finding represents an alternative strategy for achieving superconductivity in 2H-MoS_{2} in addition to chemical intercalation and electrostatic gating.

The methyl groups in hexamethylbenzene C$_6$(CH$_3$)$_6$ become magnetically ordered at the molecular level below 118 K. This is also near the temperature at which the system structurally transitions from triclinic to a unique near-cubic phase. High-precision measurements of the near-static dielectric constant reveal that the structural phase transition is actually comprised of four successive transformations upon cooling at T$_1$=110.7 K, T$_2$=109.5 K, T$_3$=109.1 K and T$_4$=107.8 K. In contrast to warming, only two transitions occur at T'$_4$=119.2 K and T'$_1$=120.9 K. The methyl groups in the near-cubic phase become slightly distorted according to existing neutron powder diffraction measurements. Analysis of the 2$^6$=64 possible spin orientation configurations of the methyl groups reveal a 20-fold ground state degeneracy presiding in each molecule rendering the system to become highly unstable. From such, it is interpreted that T$_1$ and T$_2$ are temperatures at which the molecules successively lower their symmetry to remove the energy degeneracy which involve methyl group elongation and further out-of-plane tilting. This triggers the system to phase transition into the near-cubic phase which involves a shearing of the molecular planes and partial rotation of the methyl groups at T$_3$ and T$_4$. We interpret the low temperature near-cubic phase to be a manifestation of Jahn-Teller distortions based on energy degeneracies of the orbital motion of protons in each molecule and suggest that the metastable nature of the phase transition originates from the methyl groups requiring a larger amount of energy to order than to disorder. Our findings help explain why many unusual structural phase transitions occur at low temperatures in other molecular crystals possessing periodic motion of protons., Comment: 14 pages (1.5 spaced, 3 figures + 1 'Table of Contents' graphic; accepted (on Dec. 4th, 2018) by the Journal of Physical Chemistry C

Multiferroic rare earth manganites attracted recent attention because of the coexistence of different types of magnetic and ferroelectric orders resulting in complex phase diagrams and a wealth of physical phenomena. The coupling and mutual interference of the different orders and the large magnetoelectric effect observed in several compounds are of fundamental interest and bear the potential for future applications in which the dielectric (magnetic) properties can be modified by the onset of a magnetic (dielectric) transition or the application of a magnetic (electric) field. The physical mechanisms of the magnetoelectric effect and the origin of ferroelectric order at magnetic transitions have yet to be explored. We discuss multiferroic phenomena in the hexagonal HoMnO 3 and show that the strong magneto-dielectric coupling is intimately related to the lattice strain induced by unusually large spin-phonon correlations.

The thermodynamic, magnetic, dielectric, and magnetoelectric properties of ${\text{HoFe}}_{3}{({\text{BO}}_{3})}_{4}$ and ${\text{Ho}}_{0.5}{\text{Nd}}_{0.5}{\text{Fe}}_{3}{({\text{BO}}_{3})}_{4}$ are investigated. Both compounds show a second order Ne\'el transition above 30 K and a first-order spin reorientation transition below 10 K. ${\text{HoFe}}_{3}{({\text{BO}}_{3})}_{4}$ develops a spontaneous electrical polarization below the Ne\'el temperature $({T}_{N})$ which is diminished in external magnetic fields. No magnetic-field induced increase of the polarization could be observed in ${\text{HoFe}}_{3}{({\text{BO}}_{3})}_{4}$. In contrast, the solid solution ${\text{Ho}}_{0.5}{\text{Nd}}_{0.5}{\text{Fe}}_{3}{({\text{BO}}_{3})}_{4}$ exhibits both, a spontaneous polarization below ${T}_{N}$ and a positive magnetoelectric effect at higher fields that extends to high temperatures. The superposition of spontaneous polarization, induced by the internal magnetic field in the ordered state, and the magnetoelectric polarizations due to the external field results in a complex behavior of the total polarization measured as a function of temperature and field.

Optical and synchrotron x-ray diffraction diamond anvil cell experiments have been combined with first principles theoretical structure predictions to investigate mixed N2 and H2 up to 55 GPa. We found the formation of oligomeric NxH (x>1) compounds using mechano- and photochemistry at pressures above 47 and 10 GPa, respectively, and room temperature. These compounds can be recovered to ambient pressure at T, 26 pages, 12 figures, I table

Strong anomalies of the thermal expansion coefficients at the magnetic and ferroelectric transitions have been detected in multiferroic $R{\mathrm{Mn}}_{2}{\mathrm{O}}_{5}$. Their correlation with anomalies of the specific heat and the dielectric constant is discussed. The results provide evidence for the magnetic origin of the ferroelectricity mediated by strong spin-lattice coupling in the compounds. Neutron scattering data for $\mathrm{Ho}{\mathrm{Mn}}_{2}{\mathrm{O}}_{5}$ indicate a spin reorientation at the two low-temperature phase transitions.

${\mathrm{GdFe}}_{3}({\mathrm{BO}}_{3}{)}_{4}$ exhibits a structural phase transition at $156\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, antiferromagnetic order of the ${\mathrm{Fe}}^{3+}$ moments at $36\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, followed by a spin reorientation phase transition at $9\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The reorientation phase transition is studied through dielectric, magnetic, and heat capacity measurements under the application of external magnetic fields of up to $7\phantom{\rule{0.3em}{0ex}}\mathrm{kOe}$. The dielectric constant indicates the existence of two distinct anomalies at ${T}_{SR}=9\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ that separate in temperature under external magnetic fields. The spin rotation phase transition is proven to be of the first-order nature through the magnetic analog of the Clausius-Clapeyron equation. Magnetodielectric effect of up to 1% is observed at $8\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and $7\phantom{\rule{0.3em}{0ex}}\mathrm{kOe}$. The uniaxial magnetocaloric effect along the $c$ axis is observed below the spin reorientation phase transition of $9\phantom{\rule{0.3em}{0ex}}\mathrm{K}$.

The dielectric constant of multiferroic hexagonal HoMnO_3 exhibits an unprecedented diversity of anomalies at low temperatures (1.8 K< T

Evidence for a strong spin-lattice coupling in multiferroic HoMnO_3 is derived from thermal expansion measurements along a- and c-axis. The magnetoelastic effect results in sizable anomalies of the thermal expansivities at the antiferromagnetic (T_N) and the spin rotation (T_{SR}) transition temperatures as well as in a negative c-axis expansivity below room temperature. The coupling between magnetic orders and dielectric properties below T_N is explained by the lattice strain induced by the magnetoelastic effect. At T_{SR} various physical quantities show discontinuities that are thermodynamically consistent with a first order phase transition.

GdFe3(BO3)4 exhibits a structural phase transition at 156 K, antiferromagnetic order of the Fe3+ moments at 36 K followed by a spin reorientation phase transition at 9 K. The reorientation phase transition is studied through dielectric, magnetic and heat capacity measurements under the application of external magnetic fields of up to 7 kOe. The dielectric constant indicates the existence of two distinct anomalies at T_SR = 9 K that separate in temperature under external magnetic fields. The spin rotation phase transition is proven to be of the first-order nature through the magnetic analogue of the Clausius-Clapeyron equation. Magneto-dielectric effect of up to 1% is observed at 8 K and 7 kOe. The uniaxial magnetocaloric effect along the c axis is observed below the spin reorientation phase transition of 9 K., Comment: 11 pages, 7 figures