Comment on "Modified Coulomb Law in a Strongly Magnetized Vacuum"

This is a comment on Phys. Rev. Lett. 98, 180403 (2007) [arXiv:0704.2162].Comment: 1 page, comment on arXiv:0704.2162, published versio

Improved thermal performance of a large laminated lithium-ion power battery by reciprocating air flow

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Thermal safety issues are increasingly critical for large-size laminated Lithium-Ion Batteries (LIBs). Despite a number of investigations conducted on the Battery Thermal Management System (BTMS) with reciprocating air-flow cooling, large laminated power LIBs are still not sufficiently investigated, particularly in the view of battery thermal characteristics. The present study investigates the thermal behaviors of an air-cooled NCM-type LIB (LiNi1−x−yCoxMnyO2 as cathode) from an experimental and systematic approach. The temperature distribution was acquired from different Depth of Discharge (DOD) by the infrared imaging (IR) technology. A reciprocating air-flow cooling method was proposed to restrict the temperature fluctuation and homogenize temperature distribution. Results showed that there was a remarkable temperature distribution phenomenon during the discharge process, the temperature distribution was affected by direction of air-flow. Forward air-flow (from current collector side to lower part of battery) was always recommended at the beginning of the discharge due to the thermal characteristics of the battery. After comprehensive consideration on battery temperature limit and cooling effect, the desired initial reversing timing was about 50% DOD at 3 C discharge rate. Different reversing strategies were investigated including isochronous cycles and aperiodic cycles. It was found that the temperature non-uniformity caused by heat accumulation and concentration was mitigated by reciprocating air-flow with optimized reversing strategy

Cosmological model of the interaction between dark matter and dark energy

In this paper, we test the dark matter-dark energy interacting cosmological model with a dynamic equation of state $w_{DE}(z)=w_{0}+w_{1}z/(1+z)$, using type Ia supernovae (SNe Ia), Hubble parameter data, baryonic acoustic oscillation (BAO) measurements, and the cosmic microwave background (CMB) observation. This interacting cosmological model has not been studied before. The best-fitted parameters with $1 \sigma$ uncertainties are $\delta=-0.022 \pm 0.006$, $\Omega_{DM}^{0}=0.213 \pm 0.008$, $w_0 =-1.210 \pm 0.033$ and $w_1=0.872 \pm 0.072$ with $\chi^2_{min}/dof = 0.990$. At the $1 \sigma$ confidence level, we find $\delta<0$, which means that the energy transfer prefers from dark matter to dark energy. We also find that the SNe Ia are in tension with the combination of CMB, BAO and Hubble parameter data. The evolution of $\rho_{DM}/\rho_{DE}$ indicates that this interacting model is a good approach to solve the coincidence problem, because the $\rho_{DE}$ decrease with scale factor $a$. The transition redshift is $z_{tr}=0.63 \pm 0.07$ in this model.Comment: 6 pages, 6 figures, published in A&

The structural response of a rail accelerator

The transient response of a 0.4 by 0.6 cm rectangular bore rail accelerator was analyzed by a three dimensional finite element code. The copper rail deflected to a peak value of 0.08 mm in compression and then oscillated at an amplitude of 0.02 mm. Simultaneously the insulating side wall of glass fabric base, epoxy resin laminate (G-1o) was compressed to a peak value of 0.13 mm and rebounded to a steady state in extension. Projectile pinch or blowby due to the rail extension or compression, respectively, can be identified by examining the time history of the rail displacement. The effect of blowby was most significant at the side wall characterized by mm size displacement in compression. Dynamic stress calculations indicate that the G-10 supporting material behind the rail is subjected to over 21 MPa at which the G-10 could fail if the laminate was not carefully oriented. Results for a polycarbonate resin (Lexan) side wall show much larger displacements and stresses than for G-10. The tradeoff between the transparency of Lexan and the mechanical strength of G-10 for sidewall material is obvious. Displacement calculations from the modal method are smaller than the results from the direct integration method by almost an order of magnitude, because the high frequency effect is neglected