[en] Refined vegetable oils are the main feedstocks for biodiesel production presently. However, the source and price of refined vegetable oils always restrict the development of biodiesel industry in many regions. Large amount of cheap soapstocks (SSs) are currently available in oil refining process, which may provide potential feedstocks reservoir. In this paper, one technical route involving acidification, separation of free fatty acids (FFAs) and glycerides through molecular distillation, followed by esterification and transesterification, respectively, was proposed for effective conversion of SSs. The acid oil obtained from acidification of SSs was distilled at 180 C to isolate FFAs and glycerides. Esterification was then catalyzed by solid superacid catalyst, SO₄^2-/ZrO₂-TiO₂/La³⁺, with a methanol to oil ratio of 15:1, catalyst amount of 5 wt.% and reaction time 4 h at 60 C. The conversion efficiency could reach 98.02%. Transesterification with glycerides was also carried out with methanol to oil molar ratio of 5:1 and catalyst (sodium methoxide) amount of 0.6% and reaction time 0.5 h at 55 C. The conversion efficiency could reach 97.25%. Purification of transesterification products was operated at the evaporating temperature of 120 C. The content of FAME in the distillate was above 95% analysed by gas chromatography-mass spectrometry (GC-MS). (author)

[en] In this paper, in order to investigate the residual strain relief in the fatigued copper film with a thickness of 33 μm, an unconstraint vibration treatment process was simulated by finite element (FE) method. The experimental processes, including fatigue and unconstraint vibration processes, were simulated. The fatigue process for the original specimen and the vibration process for the damaged specimen were analyzed by the static and transient dynamic analysis, respectively. The simulation results showed that the unconstraint vibration treatment can lead to the residual strain of the fatigued copper film to be reduced and redistributed. The effect of the vibration parameters on the treatment effectiveness was analyzed by the different fatigue experiments and unconstraint vibration treatments, and the results showed that the FE simulation results are in agreement with the experimental observations.

[en] We put forward a concise approach to calculate the α decay preformation probabilities by defining the microscopic valence nucleon and hole numbers based on the single particle energy spectra, which is obtained within the relativistic Hartree–Bogoliubov model. The residual interactions including neutron–neutron, proton–proton pairing and proton–neutron correlations could trigger the collective motions among the valence nucleons and holes, along with the independent particle motions under the mean field assumption. Therefore the more the number of valence nucleons and holes, the stronger the collective motions such as α particle clustering. We assume that the valence orbits locate around the Fermi surface obeying a Fermi–Dirac distribution, i.e. nucleons (holes) occupying the orbits with much lower (higher) energies away from the Fermi surface can not be considered as the valence nucleons (holes). The α decay preformation probabilities P _α are calculated within the N _p N _n scheme in terms of the valence proton–neutron interaction. As an example, in the case of even–even polonium, radon, radium and thorium isotopes the extracted α decay preformation probabilities $P_{\mathrm{\alpha <!--\; ??\; -->}}^{\mathrm{e}\mathrm{x}\mathrm{t}}$, which are obtained within the generalized liquid drop model, can be well reproduced by employing two different formulas to take into account the shell effect at N = 126 shell closure. (paper)

[en] In this paper, in order to investigate the residual strain relief in the fatigued copper film with a thickness of 33 urn, an unconstraint vibration treatment process was simulated by finite element (FE) method. The experimental processes, including fatigue and unconstraint vibration processes, were simulated. The fatigue process for the original specimen and the vibration process for the damaged specimen were analyzed by the static and transient dynamic analysis, respectively. The simulation results showed that the unconstraint vibration treatment can lead to the residual strain of the fatigued copper film to be reduced and redistributed. The effect of the vibration parameters on the treatment effectiveness was analyzed by the different fatigue experiments and unconstraint vibration treatments, and the results showed that the FE simulation results are in agreement with the experimental observations.

[en] We propose a polynomial expansion method to investigate periodic motions around both collinear and triangular libration points in the planar circular restricted three-body problem. The polynomial expansion method focuses on the approximate nonlinear polynomial relations between the two directions in the motion plane, which provide an alternative way to inspect the periodic motions. Based on the nonlinear polynomial relations, the planar two-dimensional system is decoupled. As an example, the $3\mathrm{r}\mathrm{d}$ order analytical solutions for the periodic motion are determined by solving the decoupled system. The efficiency of the polynomial expansion method has been validated by numerical method.

[en] This paper aims at establishing a new system to evaluate the level of urban energy development. With the continuous progress of urban energy transformation, it is an urgent problem to make effective use of urban energy data to evaluate the development of urban energy. By summarizing the characteristics of urban energy data and analyzing the application demand of energy management departments such as electric power enterprises at present, the basic principles of selecting energy data evaluation index are determined. Through the study of the classification of energy data, the evaluation indexes are initially selected. Then, based on the analytic hierarchy process, optimize the evaluation indexes. Finally, this paper establishes a comprehensive evaluation system which can reasonably describe the energy development model, as we see from the example of Suzhou. (paper)

[en] There are plentiful asteroids moving periodically around their central primaries, such as the Sun. Due to the perturbation of the central primary, the gravitational force of the perturbed asteroid system varies periodically. In this paper, based on the idea of integrating the solar gravitational force as a part of the system instead of treating it as perturbation, the parametric resonance response is investigated. A novel type of stable parametric resonance orbits has been detected. It is found that the steady-state motion amplitude of parametric resonance orbit is determined by the frequency-response equation. The stability of the novel orbits has also been demonstrated. The new type of orbits may contribute to possible asteroid exploration missions. (paper)

[en] Multi-wavelength continuous-wave self-Raman laser with an a-cut composite YVO₄/Nd:YVO₄/YVO₄ crystal pumped by an 879-nm wavelength-locked laser diode is demonstrated for the first time. Multi-wavelength Raman lasers at 1168.4, 1176, 1178.7, and 1201.6 nm are achieved by the first Stokes shift of the multi-wavelength fundamental lasers at 1064, 1066.7, 1073.6, 1084, and 1085.6 nm with two Raman shifts of 890 and 816 cm⁻¹. A maximum Raman output power of 2.56 W is achieved through the use of a 20-mm-long composite crystal, with a corresponding optical conversion efficiency of 9.8%. The polarization directions of different fundamental and Raman lasers are investigated and found to be orthogonal π and σ polarizations. These orthogonally polarized multi-wavelength lasers with small wavelength separation pave the way to the development of a potential laser source for application in spectral analysis, laser radar and THz generation. (paper)

[en] A series of layered (Sr_1-xK_x)Fe₂As₂ compounds with nominal x = 0-0.40 are synthesized by solid state reaction method. Similar to other parent compounds of iron-based pnictide superconductors, pure SrFe₂As₂ shows a strong resistivity anomaly near 210 K, which was ascribed to the spin-density-wave instability. The anomaly temperature is much higher than those observed in LaOFeAs and BaFe₂As₂, the two prototype parent compounds with ZrCuSiAs- and ThCr₂Si₂-type structures. K-doping strongly suppresses this anomaly and induces superconductivity. Like in the case of K-doped BaFe₂As₂, sharp superconducting transitions at T_c ∼ 38 K is observed. We perform the Hall coefficient measurement, and confirm that the dominant carriers are hole-type. The carrier density is enhanced by a factor of 3 in comparison to F-doped LaOFeAs superconductor. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

[en] We calculate the electronic structure and optical properties of F-doped anatase TiO₂. The results indicate that the band gap of F-doped TiO₂ increases slightly compared with the pure TiO₂. However, it is interesting that the visible absorption of F-doped TiO₂ located between 600 and 700 nm is observed, and it enhances gradually with the increasing F concentration. Furthermore, according to the results of densities of states and imaginary part of dielectric function element of ₂(ω), we propose that the transition between Ti 3d and Ti 3d states may be responsible for the visible absorption, but not the band gap narrowing