[en] Highlights: • A discussion on the influences of flow transition on heating capacity is proposed. • Flow transition is captured by intermittency factor within an IDDES method. • Meanwhile, flow physics behind aerodynamic performances are proposed. • The influences of evaporation and condensation temperature are discussed. - Abstract: This paper proposes a detailed discussion on the influences of flow transition on heating capacity of wind power heat pump system based on a novel improved delayed detached eddy simulation (IDDES) method and thermodynamic analysis. A numerical study of DU-212 airfoil flow field at high Reynolds number (up to 1.5 × 10⁷) is first conducted. It is found that with high Reynolds number (Re = 1.5 × 10⁷), flow transition is remarkably promoted and lower aerodynamic drag is achieved due to the decrease of momentum loss. Then, the influences of leading-edge trip on aerodynamic performances are studied and corresponding physical mechanisms are revealed. Furthermore, the heating capacity of a two-stage heat pump system is evaluated based on thermodynamic analysis. It is found that enhanced flow transition associated with leading edge trip could account for a reduction of heating capacity to at most 21.8% under certain circumstances. Eventually, the influences of evaporation and condensation temperature are briefly studied.

[en] A low-noise readout integrated circuit for high-energy particle detector is presented. The noise of charge sensitive amplifier was suppressed by using single-side amplifier and resistors as source degeneration. Continuous-time semi-Gaussian filter is chosen to avoid switch noise. The peaking time of pulse shaper and the gain can be programmed to satisfy multi-application. The readout integrated circuit has been designed and fabricated using a 0.35 μm double-poly triple-metal CMOS technology. Test results show the functions of the readout integrated circuit are correct. The equivalent noise charge with no detector connected is 500-700 e in the typical mode, the gain is tunable within 13-130 mV/fC and the peaking time varies from 0.7 to 1.6 μs, in which the average gain is about 20.5 mV/fC, and the linearity reaches 99.2%. (authors)

[en] Highlights: • A new wake model based on the Monin-Obukhov similarity theory is proposed. • The model takes roughness length and Monin-Obukhov length as input parameters. • The model is validated by a variety of experimental and LES results. • Both roughness length and atmospheric stability inuence wake recovery speed. -- Abstract: The wake flow behind a wind turbine induces a significant slowdown of wind velocity, leading to a great loss of power generation for the turbines located in the downstream region. Hence it is very important to predict the velocity in an efficient way. To satisfy this requirement, we propose a simple analytical wake model based on the Monin-Obukhov similarity theory. The new model adopts a Gaussian function and takes surface roughness length and Obukhov length into account for the first time. Then the model is validated from the following three aspects. Firstly, compared with experimental and numerical data, it is shown that the model can present a satisfactory prediction of the ambient turbulence intensities in three spatial directions and the wake expansion parameters. In addition, wind velocity deficits in the wake calculated by the model are compared with the LES data and the Lidar measurements. The results indicate that there is a good agreement with the referenced data. Finally, wake expansion parameters and wind velocity deficits are estimated for three atmospheric stabilities and compared with high resolution LES results. Even though some predicting errors exist in near wakes and for low incoming turbulence intensities, acceptable results are achieved in most of the regions of the wake. Overall speaking, roughness length and atmospheric stability have a great impact on ambient turbulence intensity, which significantly influences the velocity recovery speed in the wind turbine wake.

[en] In order to achieve the automatic analysis of the calibration data of the emanometer, the automatic evaluation system for testing emanometer is developed based on ACCESS database and . NET Framework 3.5, the software development platform of this system is VS2008. This system will automatically complete the calculation of the repeatability, volume activity response, years offset, and relative intrinsic error. Eventually, the verification report of instrument is formed through comparative analysis and related parameter will be saved into database, saving manpower and resources, and it is convenient to save and query historical data and the detection period of emanometer. (authors)

[en] Dual-vortex laser beams have been achieved in a decentered annular beam pumped Nd:YAG/Cr⁴⁺:YAG composite crystal passively Q-switched microchip laser (PQSML). The orientation and separation between two holes in dual-vortex lasers have been controlled by adjusting the offset of collimating lens with respect to the optical axis of the pump light from fiber-coupled laser diode. The offset of the collimating lens has nearly negligible effect on the performance of the decentered annular beam pumped dual-vortex Nd:YAG/Cr⁴⁺:YAG PQSML. The optical efficiency of 15.5% is achieved for dual-vortex lasers, which is comparable to that for doughnut-shaped vortex laser under normal incident pumping. Pulse width is 3.6 ns and peak power is over 5 kW for dual-vortex lasers with controllable orientation and separation between two holes. The short pulse high peak power dual-vortex lasers with controllable orientation and separation between two holes have potential applications in manipulating microparticles, data storage and quantum information processing. (paper)

[en] The development of asymmetric supercapacitors (ASCs) with high power and energy density is greatly restricted by the low capacitance of the anode materials. V₂O₅ is a promising anode material with high theoretical capacity, but its low conductivity and high dissolution are not conducive to applications in energy storage. Herein, oxygen-vacancy PEDOT/V₂O₅ ultrathin nanosheets with a thickness of about 4.4 nm are fabricated by the oxidative polymerization of EDOT monomers on V₂O₅ nanosheets in the absence of other oxidants. The results of XPS and EPR confirm that the polymerization of PEDOT increases the oxygen vacancy concentration of V₂O₅. The PEDOT/V₂O₅ nanosheets exhibit a specific capacitance of 406 F g^-1 at 2 mV s^-1 and excellent cyclic stability in the mixed organic electrolyte of dimethyl carbonate and ethylene carbonate. The energy density of ASCs composed of PEDOT/V₂O₅ as the anode and activated carbon as the cathode reaches 65 W h kg^-1 at a power density of 1490 W kg^-1. This means that PEDOT/V₂O₅ has enormous potential in high-energy storage. (authors)

[en] In this article, the effects of Ti and Zr elements addition on the microstructure and corrosion resistance of Zn-2.5Al-2Mg alloy were studied. The microstructure, micro hardness, corrosion resistance of Zn-2.5Al-2Mg alloy were investigated by x-ray diffraction (XRD), Scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS), Rockwell hardness tester and Electrochemical workstation, respectively. The result shows that the solidified structure of Zn-2.5Al-2Mg alloys was refined by Al₃Ti, Al₃Zr and Al₃(Ti, Zr) which act as a heterogeneous nucleation site. Moreover, the Rockwell hardness of Zn-2.5Al-2Mg alloys with the addition of Zr was significantly increased. The hardness of this alloy with the same amount of Zr and Ti addition is lower than that of the alloy with Zr addition alone, but obviously higher than that of the alloy with Ti alone. The corrosion resistance of the Zn-2.5Al-2Mg alloys with the same amount of Zr and Ti addition was improved significantly. (paper)

[en] The application based on current-driven domain wall (DW) motion mainly depends on the effective control of the moving velocity of the DW and its structural stability. In this paper, we show that a single square hole has a certain suppression effect on Walker breakdown (WB), and by introducing periodic square holes and improving the relevant design, a suppression effect on WB can be achieved in a limited time. As a result, the domain wall remains structurally stable while moving at a very high velocity. The size and position of the holes have an important influence on energy dissipation (ΔE) which plays a crucial role in the suppression of WB. We find that the ΔE strongly relies on the hole size (a), and theΔE has a polynomial relationship with the critical distance. When the current density is the critical value of J_WB, the square hole size a = 16 nm and the distance between adjacent holes l = 1500 nm, WB can be suppressed perfectly, and the magnetic domain wall can keep moving at high speed for a long time.

[en] Mesoporous silica nanoparticles (MSNs) can be designed to effectively load, protect, and control the release of pesticides. In this study, emulsion-solvent evaporation was used to fabricate abamectin-loaded MSNs. Our method could deliver abamectin in the process of MSN self-assembly, resulting in simple operation, short preparation period, and outstanding drug carrying capacity. The characteristics of abamectin-loaded MSNs, including morphology, loading content, stability against photolysis, controlled release behavior, and toxicological effect, were systematically investigated. Abamectin-loaded MSNs were successfully produced, having spherical shape, rough surface, uniform particle sizes, typically hollow structure, high loading efficiency (44.8%), excellent photodegradation-reducing ability, and controlled-release properties. The biological activity survey for abamectin-loaded MSNs showed excellent toxicological properties against Plutella xylostella larvae, and maintained biological activity until the 15th day, with 70% mortality of the target insect. The results of this study are beneficial for the development of a delivery system for the rational and effective usage of pesticides. (paper)

[en] Highlights: ► Ceramic system (Mg_1−xZn_x)_1.8Ti_1.1O₄ was composed by conventional solid-state route and its optimal x value (x = 0.05) was confirmed. ► ZnO was added to improve microwave dielectric properties and lower sintering temperature. Superior dielectric properties (ε_r = 15.03, Q × f = 185,000 GHz, τ_f = −45.1 × 10⁻⁶/°C) was achieved with (Mg_0.95Zn_0.05)_1.8Ti_1.1O₄ sintered at 1375 °C. ► The relationship between microstructure and properties of (Mg_1−xZn_x)_1.8Ti_1.1O₄ was investigated. ► CaTiO₃ was added to improve dielectric properties of (Mg_0.95Zn_0.05)_1.8Ti_1.1O₄ and 0.93(Mg_0.95Zn_0.05)_1.8Ti_1.1O₄–0.07CaTiO₃ was achieved for microwave application (ε_r = 18.26, Q × f = 96,060.1 GHz, τ_f = −4.6 × 10⁻⁶/°C). - Abstract: Composite dielectrics, (1 − y)(Mg_1−xZn_x)_1.8Ti_1.1O₄–yCaTiO₃, were prepared by the conventional solid-state route. The results of the X-ray diffraction and field emission scanning electron microscopy (FESEM) indicated the formation of solid solutions. Microwave dielectric properties of the composites were investigated systematically. For (Mg_1−xZn_x)_1.8Ti_1.1O₄ system, superior dielectric properties (ε_r = 15.03, Q × f = 185,000 GHz, τ_f = −45.1 × 10⁻⁶/°C) were achieved with (Mg_0.95Zn_0.05)_1.8Ti_1.1O₄ sintered at 1375 °C. CaTiO₃, as a τ_f compensator, was added to form a temperature-stable ceramic system. For (1 − y)(Mg_0.95Zn_0.05)_1.8Ti_1.1O₄–yCaTiO₃ system, 0.93(Mg_0.95Zn_0.05)_1.8Ti_1.1O₄–0.07CaTiO₃ ceramic sintered at 1375 °C had optimal dielectric properties (ε_r = 18.26, Q × f = 96,000 GHz, τ_f = −4.6 × 10⁻⁶/°C) which satisfied microwave applications in resonators, filters and antenna substrates.