Results 1 - 10 of 132
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[en] Parity-odd domains are theorized to form inside the quark–gluon plasma (QGP) created in high-energy heavy-ion collisions. The Chiral Magnetic Effect (CME) will lead to charge separation with respect to the reaction plane. Previous measurements from the RHIC and the LHC using charge-dependent two-particle azimuthal correlations are consistent with charge separations across the reaction plane, possibly induced by the CME. Such charge separation is expected to be absent if a neutral hadron is used for the correlations. The Λ(Λ¯) and KS0 are employed to test the hypothesis based on the CME expectation in Au+Au collisions at √(sNN)=200 and 39 GeV by the STAR experiment. We find no significant charge separation for Λ(Λ¯)–h± and KS0–h± azimuthal correlations. In addition, theoretical calculation predicts that the Chiral Vortical Effect (CVE) leads to a baryon number separation with respect to the reaction plane. Measurements of Λ(Λ¯)–p(p¯) azimuthal correlation are presented to search for the CVE
[en] Polymer-clay nanocomposite (PCN) materials were prepared by intercalation of an alkyl-ammonium ion spacing/coupling agent and a polymer between the planar layers of a swellable-layered material, such as montmorillonite (MMT). The nanocomposite lithium polymer electrolytes comprising such PCN materials and/or a dielectric solution (propylene carbonate) were prepared and discussed. The chemical composition of the nanocomposite materials was determined with X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy, which revealed that the alkyl-ammonium ion successfully intercalated the layer of MMT clay, and thus copolymer poly(vinylidene fluoride-hexafluoropropylene) entered the galleries of montmorillonite clay. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of the lithium polymer electrolyte. Equivalent circuits were proposed to fit the EIS data successfully, and the significant contribution from MMT was thus identified. The resulting polymer electrolytes show high ionic conductivity up to 10-3 S cm-1 after gelling with propylene carbonate. The PCN materials exhibit good electrochemical stability and could be potentially used in lithium secondary battery
[en] Highlights: • In a closed-loop heat pump drying system, the drying process is divided into two processes: heating and cooling. • A simultaneous control strategy is proposed to improve the precision of superheat and drying temperature. • Two distinct fuzzy controllers are employed to achieve more stable drying temperature. • The superheat controller is mainly composed of a PID controller and a conversion emergency controller. • The experimental data show that the simultaneous controller decreases the nonlinearities of superheat and drying temperature. - Abstract: Closed-loop heat pump drying system has its particular characteristics, and in this paper a simultaneous control strategy is proposed to improve the precision of superheat and drying temperature. The stability of drying temperature guarantees the quality of drying material. And on the premise, superheat should be accurate and stable to improve energy usage. Two fuzzy controllers employing different membership functions and control rules are used to achieve more stable drying temperature. The superheat controller is mainly composed of a PID controller and a conversion emergency controller which accelerates the response of electronic expansion valve. The experimental results show that the temperatures at the outlet of indoor and outdoor condensers give smaller fluctuations. The variations of superheat are investigated when the temperature of drying chamber changes from ambient temperature to 25/30 °C, from 25 to 30 °C and from 30 to 25 °C, respectively. All the experimental data confirm that the new controller is applicable to decrease the nonlinearities of superheat and drying temperature.
[en] The characteristics are investigated of a transient grating induced by laser in glasses doped with CdSSe semiconductor and the nonlinear response time of the material is obtained. Also the properties of photoluminescence of the glasses are studied and a blue shift in luminescence spectra with increasing intensity of the input beam is observed. It is assumed that the nonlinearity of the material is due to band filling in semiconductor microcrystallites. (author)
[en] The third-generation nuclear power plant is the latest nuclear power plant, whose application of passive cooling system has been strengthened. Passive natural convection cooling has been typically applied in the passive core cooling system and the passive containment cooling system of AP1000 reactors, and in the ESBWR reactors. Using fluid dynamics formulas and the RELAP5 code, a simple model of natural circulation loop of nuclear reactor has been established to estimate the RELAP5 natural convection calculation capability of light-water, helium and two-phase flow. The results show that the capability of natural convection is strengthened with the increase of the thermal center difference between hot and cold sources and the increases of temperature difference between the hot and cold working fluid. RELAP5 could perform natural convection calculation very well when the fluid is single water or two-phase water, in which, the errors between RELAP5 and analytical results are below 5%. When circulation fluid is helium, the error is larger than the forgoing two kinds of fluid. (authors)
[en] The effects of Zn doping in the substrate on the thermal stability of GaAs/Al0.24Ga0.76As single quantum well are investigated by 900 deg. C rapid thermal annealing and low-temperature (12 K) photoluminescence measurements. An improvement in thermal stability is demonstrated for structures grown on Zn-doped GaAs in comparison with those grown on semi-insulating and Si-doped GaAs substrates. It is likely that the Zn out-diffusion from the substrate to the quantum well region has lowered the Al-Ga interdiffusion coefficient
[en] According to China's nuclear power plant regulations and standards, the acceptance criteria based on the NUREG-0396 report is used to the plume emergency plan zoning for EPR unit. The source terms of release categories in the Level-2 PSA of the EPR unit are selected as the referenced source terms, and the individual consequence of' each source term and the weighted average of these consequences are calculated and analyzed by using MACCS code. RC205 is selected as 'the severest accident sequences' based on the frequency truncation (10-8 reactor-year), and the consequence is calculated and analyzed. As a result, 3 km internal zone radius, and 7 km outer zone radius meets the acceptance criteria. (authors)
[en] Carbon nanotubes (CNTs) enhanced carbon/carbon-lithium aluminum silicate (C/C-LAS) joint was prepared by a three-step technique of pack cementation, injection chemical vapor deposition (ICVD) and hot-pressing. A layer of aligned CNTs was grown on the surface of SiC coated C/C composites by ICVD method, and the joint was obtained by hot-pressing with magnesium aluminum silicate (MAS) as the interlayer. SEM observation reveals that the introduced CNTs result in the formation of a dense and crack-free CNT/MAS nanocomposite interface between SiC and MAS. Compared with the joints without CNTs, the average shear strength of the joints reinforced by CNTs was improved by 48% accompanied by an obvious change in failure mode from brittle fracture without CNTs to plastic fracture with CNTs. The pulling-out and bridging of CNTs on the fracture surfaces had a positive effect on the strength enhancement of the C/C-LAS joint.