Techno-economic analysis on a small-scale organic Rankine cycle with improved thermal driven pump

Acknowledgments: This research was supported by European Union’s Horizon 2020 Research and Innovation Programme under grant number (895767) and National Natural Science Foundation of China under contract number (51606118).Peer reviewedPostprin

Gravitational perturbations and electromagnetic perturbations of the Bardeen-Kiselev black hole with cosmological constant: quasinormal modes and greybody factors

In this work, we investigate a static and spherically symmetric Bardeen-Kiselev black hole with cosmological constant which is a solution of the Einstein-non-linear Maxwell field equations along with a quintessential field. We compute the quasinormal frequencies for Bardeen-Kiselev black hole(BH) with cosmological constant due to electromagnetic and gravitational perturbations. By varying the BH parameters, we discuss the behaviour of both real and imaginary parts of the BH quasinormal frequencies and compare frequencies with Reissner-Nordstr\"om-de Sitter BH surrounded by quintessence (RN-dSQ). Interestingly, it shows that the response of Bardeen-Kiselev BH with cosmological constant and RN-dSQ under electromagnetic perturbations are different when the charge parameter $q$, the state parameter $w$ and the normalization factor $c$ are varied, but for the gravitational perturbations, the response of Bardeen-Kiselev BH with cosmological constant and RN-dSQ are different only when the charge parameter $q$ is varied. Therefore, compared with the gravitational perturbations, the electromagnetic perturbations can be used to understand nonlinear and linear electromagnetic fields in curved spacetime separately. Another interesting observation is that due to the presence of quintessence, the electromagnetic perturbations around the Bardeen-Kiselev BH with cosmological constant damps faster and oscillates slowly, and for the gravitational perturbations, the quasinormal mode decays slowly and oscillates slowly. We also study the reflection and transmission coefficients along with absorption cross section for the Bardeen-Kiselev BH with cosmological constant, it shows that the transmission coefficients will increase due to the presence of quintessence

Constraints on holographic dark energy models using the differential ages of passively evolving galaxies

Using the absolute ages of passively evolving galaxies observed at different redshifts, one can obtain the differential ages, the derivative of redshift $z$ with respect to the cosmic time $t$ (i.e. ${\rm d} z/{\rm d}t$). Thus, the Hubble parameter $H(z)$ can be measured through the relation $H(z)=-({\rm d} z/{\rm d}t)/(1+z)$. By comparing the measured Hubble parameter at different redshifts with the theoretical one containing free cosmological parameters, one can constrain current cosmological models. In this paper, we use this method to present the constraint on a spatially flat Friedman-Robert-Walker Universe with a matter component and a holographic dark energy component, in which the parameter $c$ plays a significant role in this dark energy model. Firstly we consider three fixed values of $c$=0.6, 1.0 and 1.4 in the fitting of data. If we set $c$ free, the best fitting values are $c=0.26$, $\Omega_{\rm m0}=0.16$, $h=0.9998$. It is shown that the holographic dark energy behaves like a quintom-type at the $1\sigma$ level. This result is consistent with some other independent cosmological constrains, which imply that $c<1.0$ is favored. We also test the results derived from the differential ages using another independent method based on the lookback time to galaxy clusters and the age of the universe. It shows that our results are reliable.Comment: 18 pages including 7 figures and 1 tables. Final version for publication in Modern Physics Letters A (MPLA)[minor revision to match the appear version

Echoes of charged black-bounce spacetimes

In present work, the evolution of scalar field and electromagnetic field under the background of the charged black-bounce spacetimes are investigated, and we obtain an obvious echoes signal which appropriately reports the properties of the charged black-bounce spacetimes and disclose the physical reasons behind such phenomena. Furthermore, by studying the quasinormal ringdown, we analyze the three states of the charged black-bounce spacetimes in detail, our results show that the echoes signal only appears when $(\rvert {Q}\rvert \le m)$ and $(\rvert {l}\rvert > m+ \sqrt{m ^{2}-Q^{2} })$ in this spacetime, while when the parameters demand $(\rvert {Q}\rvert>m)$, the echoes signal will be transformed into a quasinormal ringdown of the two-way traversable wormhole, and the charged black-bounce is a regular black hole with normal horizons by requiring $(\rvert {Q}\rvert \le m)$ and $(\rvert {l}\rvert < m- \sqrt{m ^{2}-Q^{2} })$

Investigation on the release kinetics of chrome from finished chrome tanned leather

Content: Chrome tanning is the commonest tanning agent in leather manufacture, and the discard of chrome tanned leather goods inevitably leads to chrome discharge that might have potential environmental risks. In this study, the kinetic behaviors of the release of chrome and organics were investigated by ICP-OES and TOC analyzers respectively. Deionized water was used as medium, and leaching tests were proceed at solid liquid ratio 1:20 as well as rotational speed 60 r/min to simulate the release of chrome tanned leather under natural conditions. The effect of temperature on the behavior kinetics was further explored. The results showed that the release of chrome and organics could be well fitted by the second-order kinetic equation, and the rate constant for the release process indicated the release of organics was faster than chrome. Then Tenax model was used to illustrate the release kinetics experiments of chrome to obtain the three release compartments (fast, slow and very slow). The results could provide the theoretical parameters for the assessment of risks of chrome-tanned leather. Take-Away: The second-order kinetic equation could describe the release of chrome and organics from chrome tanned leather under natural environment. The activation energy of the release of chrome and organics from leather could be obtained. The fast, slow and very slow compartments of chrome release could be obtained