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Aircraft icing has long been a plague to aviation for its serious threat to flight safety. Recently, researches about a newly proposed deicing method based on Plasma Synthetic Jet Actuator (PSJA) have just started. To meet the requirements of in-flight deicing, structure of PSJA needs to be adjusted. This paper completed the detailed design and experimental validation of a novel plasma striker, which was a modified version of PSJA. Influences of mass of the moving part and rod shapes on the ice-breaking performances were also studied. Besides, a “conical-nosed rod configuration” was proposed. Its purpose was to ensure a good ice-breaking performance of the plasma striker on long ice, by generating a splitting failure. Results show that, though mass of the moving part was just several grams, ice-breaking performance was better when the mass was lighter. The rectangular rod could generate an elliptical circumferential crack, whose major axis was parallel to the direction of the long side of the rectangular rod. And the “conical-nosed rod” concept was verified to be able to generate a splitting crack which can spread completely to the far end of long ice, and the crack direction was parallel to edge line of the cone. In general, the plasma striker has the advantages of simple structure, low energy consumption, little harm to the flow field and the aircraft skin. Simulations will be carried out in future works to study in detail the working process of the plasma striker.

To study the influence of fillings on rock failure. By turning to the Drucker-Prager strength model and cumulative damage criteria, investigations are made, with the nonlinear AUTODYN software, into crack propagation behaviors in crack-filled and unfilled specimens under uniaxial dynamic loading. Under investigations are crack initiation position, sequence and angle, and coalescence mode. According to the mode of propagation and coalescence, cracks are divided into three types, i.e., the tensile wing, the antiwing, and the horsetail. The simulation results show that under uniaxial dynamic loading, differences are found in initiation position, angle, and coalescence mode for specimens with cracks filled or otherwise. However, filling does not affect crack initiation sequence. Under the same loading, the damage to filled specimen is less severe than that to the unfilled specimen.

The interaction between self-sustaining dual jets and supersonic laminar boundary layer is experimentally studied using the nanoparticle-based planar laser scattering in a Ma 2.95 supersonic low-turbulence wind tunnel for the first time. The typical fine flow structures, such as separation shock, “W” bow shock, barrel shock, horseshoe vortex, large-scale vortex structures and counter-rotating vortex pairs, are clearly identified by streamwise and spanwise flowfield images. The curves of jet penetration depth are fitted at the momentum ratio of 0.55 between self-sustaining dual jets and supersonic crossflow. The results play a significant role in further and comprehensive exploration of the active flow control for a supersonic flow.

A color tunable emission was obtained in CaHfO3:Ce3+,Tb3+ phosphor. XRD, luminescence spectra, decay curves, temperature-dependent emission spectra and quantum efficiency were used to characterize the structure and luminescence properties. Under 330 nm excitation, the Ce3+ singly doped CaHfO3 samples exhibited intense blue emission. The emission intensity reached the maximum at 1 mol% Ce3+. CaHfO3:0.1Ce3+ samples possessed high quantum efficiency of 52.05%. In Tb3+ co-doped CaHfO3:Ce3+ phosphors, the emission position of Ce3+ blue shifts slightly due to weaker crystal field strength around Ce3+. Besides, the energy transfer between Ce3+ and Tb3+ leads to tunable emission colors from blue to cyan, then to green. The energy transfer efficiency and thermal stability are investigated in detail.

A velocity-temperature coupled control method is proposed for turbulence drag reduction of supersonic boundary layers. Direct numerical simulations indicate that heated wall blowing achieves the best drag reduction, whereas cooled wall blowing leads to a drag increase. The reduction of mean viscous shear stress is mainly responsible for the drag reduction mechanism, though there is a substantial increase in Reynolds stresses. Nevertheless, the control efficiency of heated wall blowing is low due to high energy consumption, but further investigation is needed.

Geometrically nonlinear dynamic analysis of functionally graded carbon nanotube reinforced composite (FG-CNTRC) rectangular plates subjected to blast loads is conducted based on Reddy’s higher-order shear deformation theory using the weak form quadrature element method. The von-Karman strain terms are introduced to consider the geometrically nonlinear effects . The polymer composite plate is reinforced by single-walled carbon nanotubes (SWCNTs) with the uniform and functionally graded distribution in the plate thickness direction. The effective material properties of the FG-CNTRC plates are estimated with the extended rule of mixture. The Newmark- β time integration scheme and the Newton–Raphson iteration technique are adopted to solve the nonlinear incremental dynamic equilibrium equation in temporal domain. Comparative and convergence studies are carried out to validate the accuracy, efficiency and numerical stability of the presented weak form quadrature element formulation. The effects of the carbon nanotube distribution and volume fraction, plate width-to-thickness ratio, plate aspect ratio, load type and boundary condition on the dynamic response of the FG-CNTRC plates under blast loads are systematically investigated through the parametric studies .

Pr3+/Er3+ co-doped tellurite glass with composition 80TeO2-10Na2O-5WO3-5Nb2O5 was synthesized by the conventional melt-quenching technique, and the obtained glass was characterized by the UV/Vis/NIR absorption spectrum, near-infrared fluorescence spectrum, differential scanning calorimeter (DSC) curve, X-Ray diffraction (XRD) pattern and Raman spectrum. Under the 488 nm excitation, it was found that Pr3+/Er3+ co-doped tellurite glass could emit an ultra-broadband near-infrared fluorescence which extended from 1200 to 1650 nm with full-width at half-maximum (FWHM) of about 236 nm, and this ultra-broadband fluorescence was contributed by the multichannel emissions of Pr3+ and 1.53 µm band emission of Er3+. The luminescent mechanism and energy transfer processes between Pr3+ and Er3+ ions which are responsible for the observed ultra-broadband fluorescence were analyzed. Meanwhile, optical absorption bands that are assigned with corresponding electronic transitions with respect to Pr3+ and Er3+ ions were identified from the measured absorption spectrum, and based on the optical absorption data, the gain coefficient and important spectroscopic parameters like Judd-Ofelt intensity parameter, spontaneous radiative transition probability, radiative lifetime and branching ratio were calculated to elucidate the radiative properties of doped rare-earth ions. In addition, the DSC curve exhibited the good thermal stability of glass host with Δ T >150 °C, Raman spectral study displayed the presence of different vibrational groups and XRD pattern confirmed the amorphous structural nature of the prepared glass. The present results indicate that Pr3+/Er3+ co-doped tellurite glass is promising for the ultra-broadband near-infrared band fiber amplifiers covering the expanded low-loss communication window.

Improving the lasing emission property of rare-earth doped vitreous material is a research topic. In this paper, Er3+/Yb3+/Tm3+ tri-doped tellurite glasses with and without WO3 component were synthesized using melt-quenching technique and the effect of WO3 addition on the 1.80 μm band fluorescence of Tm3+ was investigated. The obtained samples were characterized by X-ray diffraction (XRD) pattern, differential scanning calorimeter (DSC) curve, Raman spectrum, UV/Vis/NIR absorption spectrum, near-infrared emission spectrum and fluorescence decay curve. The XRD pattern confirmed amorphous structural nature of synthesized tellurite glass, the DSC curve revealed good thermal stability with Δ T >100 °C and the Raman spectrum displayed a stretching vibration band around 920 cm−1 for glass host with WO3. Under the excitation of 980 nm laser diode (LD), the intense 1.80 μm band fluorescence of Tm3+ originated from the 3F4→3H6 transition was observed in the Er3+/Yb3+/Tm3+ tri-doped tellurite glass and the intensity increases further with the addition of a certain amount of WO3, which is attributed to the enhanced energy transfers from Yb3+ (Er3+) to Tm3+ ions due to the increased phonon energy of glass host. The energy transfer mechanism between them was elucidated by analyzing fluorescence decay behavior of Tm3+ and quantitatively calculating energy transfer coefficient as well as phonon contribution ratio. Meanwhile, based on the absorption spectrum, some important spectroscopic parameters such as Judd-Ofelt parameter, spontaneous radiative transition probability, fluorescence branching ratio, absorption and emission cross-sections, and gain coefficient spectrum were calculated to reveal spectroscopic properties of doped Tm3+ ions. The obtained results indicate that Er3+/Yb3+/Tm3+ tri-doped tellurite glass with an appropriate amount of WO3 is a promising gain medium applied for the 1.80 μm band solid-state lasers.

In this work, the near-infrared photoluminescence properties in Tm3 +/Ho3 + co-doped tellurite glass was investigated. The tellurite glass with composition TeO2-ZnO-Na2O-La2O3 was synthesized using conventional melt-quenching technique and characterized by UV/Vis/NIR absorption and near-infrared emission spectroscopies, fluorescence decay measurement and differential scanning calorimeter (DSC) analysis. Under the excitation of 808 nm laser diode (LD), a broadband 2.0 μm band luminescence ranging from 1600 to 2200 nm with a full width at half maximum (FWHM) of 362 nm was observed, which was contributed by 1.85 μm fluorescence from Tm3 +: 3F4 → 3H6 and 2.05 μm fluorescence from Ho3 +: 5I7 → 5I8. The fluorescence emission of Ho3 + was originated from the energy transfer from Tm3 + to Ho3 + ions, and the energy transfer mechanism was elucidated by analyzing fluorescence decay behavior of Tm3 + and quantitative calculation of phonon contribution joined in the energy transfer process. Meanwhile, based on the absorption spectrum, some important spectroscopic parameters such as Judd-Ofelt intensity parameter, spontaneous radiative transition probability, fluorescence branching ratio, absorption and emission cross-sections, and gain coefficient spectrum were calculated to reveal the spectroscopic properties of doped tellurite glass. Furthermore, from the DSC curve it can be derived that the investigated glass possesses a good thermal stability with ΔT(= Tx − Tg) larger than 152 °C. These results indicate that Tm3 +/Ho3 + co-doped tellurite glass could be a promising gain medium applied for 2.0 μm near-infrared band broad fiber amplifiers and tunable fiber lasers.

Pr3+-doped tellurite glasses containing metallic silver NPs were synthesized by the conventional melt-quenching technique. Structural, thermal and optical properties of the synthesized glass samples were characterized by X-Ray diffraction (XRD) curves, Raman spectra, differential scanning calorimeter (DSC) curves, transmission electron microscopy (TEM) images, UV/Vis/NIR absorption and near-infrared fluorescence emission spectra. The XRD curves confirmed the amorphous structural nature of the synthesized glasses, the Raman spectra identified the presence of different vibrational groups, the DSC curves verified the good thermal stability, and the TEM images revealed the nucleated silver NPs with average diameter about 10 nm dispersed in the glass matrix and its surface Plasmon resonance (SPR) absorption band was located at around 510 nm. Besides, Judd-Ofelt intensity parameters Ω t (t = 2, 4, 6) and other important spectroscopic parameters like transition probability, radiative lifetime, branching ratio were calculated to evaluate the radiative properties of Pr3+ levels from the measured optical absorption spectra. It was found that Pr3+-doped tellurite glasses could emit an ultra-broadband fluorescence extending from 1250 to 1650 nm under the 488 nm excitation, and this fluorescence emission increased further with the introduction of silver NPs. The enhanced fluorescence was mainly attributed to the increased local electric field around Pr3+ induced by silver NPs. The present results demonstrate that Pr3+-Ag codoped tellurite glass is a promising candidate for the near-infrared band ultra-broadband fiber amplifiers covering the expanded low-loss communication window.

This paper reports an enhanced and broadband near-infrared fluorescence emission in the Pr3+/Nd3+ co-doped tellurite glass, which was prepared using melt-quenching technique. Under the excitation of 488 nm laser diode (LD), three near-infrared emission bands at around 0.9, 1.04 and 1.30 μm from 3P1,0 → 1G4, 1G4→3H4 and 1G4→3H5 radiative transitions respectively were observed in the Pr3+ single-doped glass, and the fluorescence intensities increased further with the introduction of Nd3+ ions, which is mainly attributed to the energy transfers from Nd3+ to Pr3+ emissions. Meanwhile, the spectral overlapping of Pr3+:1G4→3H4 and Nd3+:4F3/2 → 4I11/2 radiative transitions resulted in a broadband emission ranging from 1000 to 1100 nm, whose full-width at half-maximum (FWHM) reached about 66 nm. Additionally, the spectroscopic properties of Nd3+ and Pr3+ ions were analyzed using Judd-Ofelt theory and the thermal stability property of prepared glass was characterized by the differential scanning calorimeter (DSC) measurement, and larger than 134 °C for the difference Δ T ( = T x − T g ) was observed, which indicates its feasibility for later fiber drawing. The enhanced fluorescence and broadband emission indicate that Pr3+/Nd3+ co-doped tellurite glass can be applied in the near-infrared band tunable lasers and broadband optical amplifiers.

The B 2 O 3 oxide in different concentration was introduced into Er 3+ /Ho 3+ codoped tellurite glass with conventional composition TeO 2 ZnO Na 2 O to investigate its effect on the near-infrared band luminescence of doped rare-earth ions under the excitation of 980 nm LD. The UV/Vis/NIR absorption spectrum, Vis/NIR fluorescence emission spectrum, fluorescence decay curve, DSC curve and Raman spectrum of the prepared glass samples were measured and investigated. With the introduction of B 2 O 3 in a certain concentration range, the 1.55 μm band fluorescence of Er 3+ improved greatly, whereas the 2.03 μm band one of Ho 3+ decreased first and then increased slightly. The Judd-Ofelt intensity parameter, radiative transition probability, quantum efficiency, multi-phonon relaxation rate and energy transfer micro-parameter were calculated to explain the obtained experimental results. The present works indicate that the enhanced multi-phonon relaxation of excited state ions and energy transfer between Er 3+ and Ho 3+ ions due to the increased phonon energy of glass host with the introduction of B 2 O 3 are responsible for the observed luminescent phenomena, and Er 3+ /Ho 3+ codoped tellurite glass with an appropriate amount of high phonon energy B 2 O 3 is a promising candidate applied for the near-infrared band solid-state lasers and fiber amplifiers.

Tellurite glasses with different concentrations of Nd3 + ions and WO3 oxide were prepared using melt-quenching technique. The prepared glasses were characterized by the absorption spectrum, emission spectrum, Raman spectrum, fluorescence decay curve and DSC curve measurements, together with Judd-Ofelt intensity parameter, radiative transition probability and fluorescence branching ratio calculations to reveal the effects of Nd3 + and WO3 concentration on the structure, photo-luminescence and thermal stability. Under the excitation of 808 nm LD, three near-infrared band fluorescence emissions at around 0.9, 1.06 and 1.34 μm, corresponding to the transitions from the 4F3/2 → 4I9/2, 4I11/2 and 4I13/2 levels respectively, are observed, and the fluorescence intensities increase with the increase of doped Nd3 + concentration up to 0.6 mol%. Furthermore, the fluorescence intensities continue to increase greatly with the introduction of WO3 oxide. Compared with 0.6 mol% Nd3 +-doped glass without WO3 oxide, the luminescent intensity of 1.06 μm band increases by about 95% in the glass with 9 mol% amount of WO3, which is mainly attributed to the rapid population of Nd3 + ions in the excited level 4F3/2 due to the enhanced multi-phonon relaxation process with the increased phonon energy of glass host. Therefore, the enhanced luminescent intensity as well as the good thermal stability demonstrated by DSC curve indicate that the prepared 0.6 mol% Nd3 +-doped tellurite glass with 9 mol% amount of WO3 oxide is a potential gain medium applied for near-infrared band solid-state lasers and fiber amplifiers.

Metallic silver nanoparticles (Ag NPs) with various concentrations were embedded into Er3+/Tm3+/Yb3+ tri-doped tellurite glasses prepared using melt-quenching and heat-treated techniques. Heat-treatment at temperature above the glass transition temperature induced the nucleation and growth of near-spherical shape silver NPs confirmed by the transmission electron microscopy (TEM) images, and the average diameter of silver NPs was about 10 nm. The thermal stability, structural and optical properties of the prepared glasses were characterized by the differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) patterns, absorption spectra, luminescence spectra and fluorescence decay curves. The DSC curves displayed that the prepared glasses possess good thermal stability with ∆ T larger than 138 °C while the XRD patterns indicated the amorphous structural nature. Under the excitation of 980 nm LD, the luminescence spectra exhibited two intense near-infrared band fluorescence at 1.81 and 1.53 μm in the wavelength range of 1400–2200 nm, which are originated from the Tm3+:3F4 → 3H6 and Er3+:4I13/2 → 4I15/2 transitions respectively. With the embedding of 0.5 mol % amount of silver NPs, the 1.81 μm band fluorescence of Tm3+ increased significantly by about 70%, mainly due to the local electric field enhanced effect induced by silver NPs on the basis of energy transfers from Er3+ to Tm3+ ions, and the energy transfer efficiency, micro-coefficient and critical radius were calculated to elucidate the interaction mechanism between Er3+ and Tm3+ ions. Additionally, the intensity parameters Ω t (t = 2, 4, 6) and radiative properties of Tm3+ such as the transition probabilities, radiative lifetimes and branching ratios were calculated from the measured absorption spectra based on Judd-Ofelt theory. The present results indicate that the Er3+/Tm3+/Yb3+ tri-doped tellurite glass with an appropriate amount of silver NPs is a promising luminescent material applied for the near-infrared band solid-state lasers and fiber amplifiers.

WO3 oxides with relatively high phonon energy and different concentrations were introduced into the Nd3+-doped tellurite-based glasses of TeO2-ZnO-Na2O to improve the 1.32 μm band fluorescence emission. The absorption spectra, Raman spectra, 1.32 μm band fluorescence spectra and differential scanning calorimeter (DSC) curves were measured, together with the Judd-Ofelt intensity parameters, stimulated emission and gain parameters were calculated to evaluate the effects of WO3 amount on the glass structure and spectroscopic properties of 1.32 μm band fluorescence. It is shown that the introduction of an appropriate amount of WO3 oxide can effectively improve the 1.32 μm band fluorescence intensity through the enhanced multi-phonon relaxation (MPR) processes between the excited levels of Nd3+. The results indicate that the prepared Nd3+-doped tellurite glass with an appropriate amount of WO3 oxide is a potential gain medium applied for the O-band broad and high-gain fiber amplifier.

The Er 3+ /Tm 3+ co-doped tellurite glasses with and without silver nanoparticles (Ag NPs) have been synthesized by the conventional melt-quenching technique and characterized by the UV/Vis/NIR absorption spectra, 1.85 μm band fluorescence emission spectra, differential scanning calorimeter (DSC) curves, X-ray diffraction (XRD) curves and transmission electron microscopy (TEM) images to investigate the effects of Ag NPs on the 1.85 μm band spectroscopic properties of Tm 3+ ions, thermal stability and structural nature of glass hosts. The TEM image reveals the presence of Ag NPs with average diameter of ∼14 nm in the prepared Er 3+ /Tm 3+ co-doped tellurite glasses, and the presence of Ag NPs significantly enhance the 1.85 μm band fluorescence emission of Tm 3+ ions under the excitation of 808 nm LD, which is mainly attributed to the intensified local electric field induced by Ag NPs scattered around the doped rare-earth ions, together with the energy transfer between Er 3+ and Tm 3+ ions. The energy transfer mechanisms between Er 3+ and Tm 3+ ions were further investigated by calculating energy transfer micro-parameters and phonon contribution ratios. Meanwhile, the Judd-Ofelt intensity parameters Ω t ( t = 2,4,6), spontaneous radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of relevant excited levels of Tm 3+ ions were calculated based on the Judd-Ofelt theory to reveal the improved effects of Ag NPs on the 1.85 μm band spectroscopic properties. An improvement by about 75% of fluorescence intensity is found in the studied Er 3+ /Tm 3+ co-doped tellurite glass containing 1.0 mol% amount of Ag NPs, and the thermal stability of glass host increases slightly with the Ag NPs while the glass structure maintains the amorphous nature. The above results indicate that the prepared Er 3+ /Tm 3+ co-doped tellurite glass with an appropriate amount of Ag NPs is a promising host material applied for 1.85 μm band solid-state lasers and amplifiers.

Tm3+/Yb3+ co-doped tellurite glasses with different silver nanoparticles (Ag NPs) concentrations were prepared using the conventional melt-quenching technique and characterized by the UV/Vis/NIR absorption spectra, 1.85 μm band fluorescence emission spectra, transmission electron microscopy (TEM) images, differential scanning calorimeter (DSC) curves and X-ray diffraction (XRD) patterns to investigate the effects of Ag NPs on the 1.85 μm band spectroscopic properties of Tm3+ ions, thermal stability and structural nature of glass hosts. Under the excitation of 980 nm laser diode (LD), the 1.85 μm band fluorescence emission of Tm3+ ions enhances significantly in the presence of Ag NPs with average diameter of ∼8 nm and local surface Plasmon resonance (LSPR) band of ∼590 nm, which is mainly attributed to the increased local electric field induced by Ag NPs at the proximity of doped rare-earth ions on the basis of energy transfer from Yb3+ to Tm3+ ions. An improvement by about 110% of fluorescence intensity is observed in the Tm3+/Yb3+ co-doped tellurite glass containing 0.5 mol% amount of AgNO3 while the prepared glass samples possess good thermal stability and amorphous structural nature. Meanwhile, the Judd-Ofelt intensity parameters Ω t (t = 2,4,6), spontaneous radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of relevant excited levels of Tm3+ ions were determined based on the Judd-Ofelt theory to reveal the enhanced effects of Ag NPs on the 1.85 μm band spectroscopic properties, and the energy transfer micro-parameters and phonon contribution ratios were calculated based on the non-resonant energy transfer theory to elucidate the energy transfer mechanism between Yb3+ and Tm3+ ions. The present results indicate that the prepared Tm3+/Yb3+ co-doped tellurite glass with an appropriate amount of Ag NPs is a promising lasing media applied for 1.85 μm band solid-state lasers and amplifiers.

For enhancing the 2.0 μm band fluorescence of Ho3+, a certain amount of WO3 oxide was introduced into Ho3+/Tm3+/Yb3+ tri-doped tellurite glass prepared using melt-quenching technique. The prepared tri-doped tellurite glass was characterized by the absorption spectra, fluorescence emission and Raman scattering spectra, together with the stimulated absorption, emission cross-sections and gain coefficient. The research results show that the introduction of WO3 oxide can further improve the 2.0 μm band fluorescence emission through the enhanced phonon-assisted energy transfers between Ho3+/Tm3+/Yb3+ ions under the excitation of 980 nm laser diode (LD). Meanwhile, the maximum gain coefficient of Ho3+ at 2.0 μm band reaches about 2.36 cm-1. An intense 2.0 μm fluorescence emission can be realized.

The significant criterion for evaluating the merits of a new type of high molecular polymer lies in its engineering properties and eco-friendliness. The focus of this study was to determine the effects of preparation conditions on the viscosity of the polyvinyl acetate (PVAc) emulsion, including reaction temperature (Tr), initiator concentration (CAPS), monomer concentration (CVA), pH value, and degree of dilution (Ddi). Based on the results of a series of laboratory tests, the range of viscosity value of PVAc was obtained under different conditions, and one set of viscosity values out of these was applied to soil reinforcement tests. Meanwhile, based on the test results, the engineering properties of PVAc solution were evaluated using strength and moisture retention tests, and the reinforcement mechanism was analyzed using scanning electron microscopy (SEM). In addition, it was proven through a vegetation growth test that the PVAc was eco-friendly.

Improving the spectroscopic properties of rare earth (RE) doped glass materials is a challenging task. In the present work the metallic silver nanoparticles (Ag NPs) were embedded into Er 3+ /Yb 3+ codoped tellurite glasses with composition TeO 2 –Bi 2 O 3 –TiO 2 , prepared using melt-quenching and subsequent heat-treated techniques, and the improved effect of Ag NPs on the 1.53 μm band fluorescence of Er 3+ ions was investigated. About 24 h heat-treatment of Er 3+ /Yb 3+ codoped tellurite glass containing 1 mol % amount of AgNO 3 at the temperature 370 °C yielded the well-dispersed and near-spherical Ag NPs with ∼11.4 nm average diameter as evidenced by transmission electron microscopy (TEM) image. The intense 1.53 μm band fluorescence was observed in the prepared Er 3+ /Yb 3+ codoped tellurite glasses under the excitation of 980 nm and was further improved with the presence of Ag NPs in the glass matrix, which is attributed to the enhanced local electric field around doped RE ions induced by Ag NPs and the possible energy transfer from Ag NPs to Er 3+ ions. The enhanced local electric field was well demonstrated by comparing the variation of emission spectra of hypersensitive probe Eu 3+ ions in tellurite glasses with and without Ag NPs. From the Judd-Ofelt analysis, it was also found that the value of Ω 6 intensity parameter increased slightly with the increase of Ag NPs concentration in a certain range, also confirming the possibility of realizing strong fluorescence emission. In addition, the amorphous structural nature was demonstrated by the measured X-ray diffraction (XRD) patterns with no sharp diffraction peak. The enhanced 1.53 μm band fluorescence indicates that the Er 3+ /Yb 3+ codoped tellurite glass with an appropriate amount of Ag NPs is a promising candidate for the development of Er 3+ -doped fiber amplifiers (EDFAs) applied in the WDM systems.

High performance inverted polymer solar cell is demonstrated by introducing a nanostructured backscattering rear electrode, which is fabricated by embedding silver nanoparticle (NP) arrays into the MoO3 hole extraction layer. As verified by characterizing and simulating the electrical and optical properties, such a nanostructured rear electrode can achieve an improved cell performance by maintaining simultaneously high open-circuit voltage and fill factor values, while providing excellent short-circuit current enhancement through efficient backscattering-induced light trapping. A careful optimization of the nanostructured rear electrode can result in polymer solar cells with an enhanced power conversion efficiency of 7.21%, as compared to 6.26% of the reference cell with a flat electrode. It is noteworthy that the method described here offers a convenient and scalable way for inexpensive and high-performance polymer solar cell designs.

The effects of exhaust temperature on infrared signature (in 3–5 μm band) for a helicopter equipped with integrative infrared suppressor were numerically investigated. The internal flow of exhaust gas and the external downwash flow, as well as the mixing between exhaust gas and downwash were simulated by CFD software to determine the temperature distributions on the helicopter skin and in the exhaust plume. Based on the skin and plume temperature distributions, a forward–backward ray-tracing method was used to calculate the infrared radiation intensity from the helicopter with a narrow-band model. The results show that for a helicopter with its integrative infrared suppressor embedded inside its rear airframe, the exhaust temperature has significant influence on the plume radiation characteristics, while the helicopter skin radiation intensity has little impact. When the exhaust temperature is raised from 900 K to 1200 K, the plume radiation intensity in 3–5 μm band is increased by about 100%, while the skin radiation intensity is increased by only about 5%. In general, the effects of exhaust temperature on helicopter infrared radiation intensity are mainly concentrated on plume, especially obvious for a lower skin emissivity case.

An impact rotary motor based on a bulk piezoelectric torsional actuator with grooved helical electrodes is proposed. The prototype actuator, with dimensions of Φ 8 mm × 10 mm, produces a maximum torsional angle of 0.035° with a driving voltage of 2200 Vp-p. Its first torsional resonant frequency is 32 kHz with the fixed-free boundary condition. The rotational speed of the developed motor is proportional to both the amplitude and the frequency of the driving voltage in low frequency range. With a saw-shaped driving voltage of 1400 Vp-p at 8 kHz, the motor can rotate at a speed of 22.5 r/min with a braking torque of 0.1 mN·m, and the stall torque can reach up to 1.6 mN·m. Although its maximum efficiency is less than 0.1%, the motor produces a rather small step angle with a large driving torque. It is suitable for ultrahigh precision positioning.

Two-photon microscopy (TPM) has been one of the most widely used fluorescent microscopy methods in biological tissue. The femtosecond laser in the near-infrared (NIR) range showed better penetration in tissue due to less scattering and absorption. The method to estimate the optimal wavelength generally according to the scattering and absorption is somehow too rough considering the complex biological property and other factors that influence TPM. In this report, we set up a model to calculate the optimal wavelength in the NIR range for different imaging depths by involving more parameters of TPM. The calculated result suggests the image of brain slice stained with fluorescein isothiocyanate (FITC) can be acquired with the best TPM imaging quality at 780 nm excitation rather than longer wavelengths, which is consistent with our experimental results of TPM at depth of 50-300 μm in mouse brain tissue. Our results may, therefore, bring a better understanding on TPM in tissue and help to develop a more accurate model for the simulation of TPM.

Three-dimensional numerical calculation was performed to investigate the effects of partial blockage inside cylindrical film holes on the film cooling effectiveness over a flat plate. Five blockage ratios ranged from 0.1 to 0.5 and a series of blockage positions were considered under the blowing ratios of 0.3–1.5. It is found that the blockage position has a significant influence on mainstream-coolant jet interaction. The partial blockage located at the leading edge of coolant-hole exit mitigates the primary vortices due to mainstream-coolant jet interaction. The coolant jet penetration along vertical direction is suppressed and the peak velocity along streamwise direction is augmented under the action of partial blockage at the upstream side of film holes, providing an increment of film cooling effectiveness, especially under high blowing ratio. While the partial blockages located at the trailing or lateral edges of coolant-hole exit weaken the film cooling effectiveness. In relation to the partial blockage located in the vicinity of coolant-hole exit, the partial blockage located in the vicinity of coolant-hole inlet or middle has less impaction on the film cooling effectiveness under low blowing ratio.

In this paper, for four groups of recycled concrete specimen in early shrinkage and re- straint cracking experiment, which the recycled aggregate replacement ratio of 100% and the waste fiber volume content of 0, 0.08%, 0.12%, 0.16%. Experimental results show that: when the volume content of waste fiber is 0.08%, the effect of reducing shrinkage is more obvious, while the volume content of waste fiber is 0.12%, the performance of anti-cracking is the best.

Enhanced performance of polymer solar cells is reported by incorporating a solution-processed luminescent down-shifting (LDS) sensitizer, which is composed of a C545T fluorescent molecule doped tris(8-quinolinolato) aluminum (C545T:Alq3). An optimized LDS sensitizer can result in ∼15% enhancement in power conversion efficiency than the reference device with pristine Alq3. The performance enhancement is associated with the increase in photocurrent induced by LDS sensitizer, which is capable of absorbing short-wavelength solar spectrum and re-emitting long-wavelength light, which is complementary with the absorption spectrum of the active layer. This method provides a facile approach for high-performance polymer solar cell designs.

A series of Ge films with varying thickness is prepared by plasma enhanced chemical vapor deposition technology. With the thickness of the sample becoming thinner, the sample shows ferromagnetism. When the 12-nm-thick sample is annealed at 300℃, the partile size becomes smaller, and thus the number of interface defects between the particles increases, so the sample gives a largest magnetic signal at room temperature (50 emu/cm3). FC-ZFC measurement shows that Curie temperature is 350 K. For a higher temperature (600 ℃, the coalescence of small Ge particles makes surface area decline, so magnetic signal becomes weak. With the thickness being 6 nm, the paramagnetism and the ferromagnetism coexist in the 6-nm-thick Ge film. When the 6-nm-thick sample is annealed under nitrogen atmosphere at 300 ℃, the sample only shows ferromagnetism. However, annealed at 600 ℃, the sample only presents paramagnetism. With the annealing temperature changing, the 12-nm-thick film and the 6-nm-thick film show different magnetic phenomena. Particle size and particle distribution cause different magnetic phenomena. It is supposed that the Ge nannostructure unpaired electrons are provided mainly by the interface defect between Si matyix and Ge film and the surface defect of Ge particles. The ferromagnetism coupling of the unpaired electrons is related to the distribution of sample particles and the junction among particles. The fusion between particles will reduce the ferromagnetism of the sample.

Surface plasmon-enhanced electroluminescence (EL) in an organic light-emitting diode is demonstrated by incorporating the synthesized Au nanoparticles (NPs) in the hole injection layer of poly(3,4-ethylene dioxythiophene):polystyrene sulfonic acid. An increase of ∼25% in the EL intensity and efficiency are achieved for devices with Au NPs, whereas the spectral and electrical properties remain almost identical to the control device. Time-resolved photoluminescence spectroscopy reveals that the EL enhancement is ascribed to the increase in spontaneous emission rate due to the plasmonic near-field effect induced by Au NPs.

The effect of gold nanoparticle (NP)-induced surface plasmons on the performance of polymer solar cells (PSCs) is investigated by blending the solution processable Au NP-adhered graphene oxide (Au-GO) into the anodic buffer layer of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The incorporation of Au-GOs provides a simple method to introduce a plasmonic effect, which is helpful to avoid aggregation of Au NPs blended in PEDOT:PSS. The addition of Au-GOs increased the light absorption and exciton generation rate in the active layer, thereby enhancing the short-circuit current and power conversion efficiency of these PSCs. According to the experimental and simulated results, the improvement in device performance can be ascribed to the near-field enhancement arising from the excitation of the localized surface plasmon resonance of Au-GOs along the active layer/PEDOT:PSS interface. Our work indicates the great potential of Au-GOs for high-efficiency plasmonic-enhanced PSC applications.

The enhanced performance of inverted polymer solar cells enabled by a plasmonic backscattering effect is reported upon. To produce localized surface plasmons (LSPs) at the rear anode, thermally deposited Ag nanoparticles (NPs) are embedded in the MoO3 hole extraction layer. Upon optimizing the MoO3/Ag NPs/MoO3 sandwich structure, enhanced light harvesting is achieved via plasmonic backscattering into the photoactive layer of poly(3-hexylthiophene)/[6,6]-phenyl-C61 butyric acid methyl ester (P3HT:PCBM), resulting in an increase in photocurrent without sacrificing electrical properties, and ∼20% enhancement in power conversion efficiency, of 4.32% vs. 3.61% of the reference device. The performance improvement of the inverted PSCs is ascribed to the enhanced light absorption as a result of the light backscattering as well as the excitation of LSPs induced by Ag NPs embedded in the MoO3 layer. The present method provides a promising pathway for the fabrication of high-efficiency PSCs in an inexpensive and scalable way.

Enhanced performance of a poly(3-hexylthiophene):(6,6)-phenyl C61 butyric acid methyl ester bulk heterojunction polymer photovoltaic cell is reported by modifying the indium tin oxide (ITO) anode with chloroform solution. Instead of the traditional UV-ozone treatment, the optimized chloroform modification on ITO anode can result in an enhancement in the power conversion efficiency of an identical device, originating from an increase in the photocurrent with negligible change in the open-circuit voltage. The performance enhancement is attributed to the work function modification of the ITO substrate through the surface incorporation of the chlorine, and thus improved charge collection efficiency.

Room-temperature ferromagnetism (FM) is observed in Si-Al2O3 amorphous composite film. The magnetic moment is the highest in the case of the Si-Al2O3 composite films with the Si content being 15 vol.%, and distinct domains are detected in our films. The difference in magnetism property between sample annealed in Ar atmosphere and untreated composite film indicates that the observed ferromagnetism does not originate primarily from oxygen defects. It is concluded that the ferromagnetism arises from the direct coupling between defects. These defects orignate from the interface between Si particles and Al2O3 matrix. By varying the Si content in the film, one can change the defect density and thereby control the strength of the ferromagnetic coupling.

Polycrystalline samples of La0.8-xCa0.2MnO3(x=0,0.01,0.03,0.05,0.08,0.1) were synthesized using a sol-gel technique. Structure analysis, morphology observation and magnetic measurement have been used to study the effect of vacuum concentration of La3+ on the Curie temperature and magnetic entropy change of La0.8-xCa0.2MnO3. The experimental results show that by tuning the vacuum concentration of La\+\{3+\}, the materials could exhibit very different Curie temperatures (from 180 to 260K). All the samples in this paper have large magnetic entropy change, especially for La0.77Ca0.2MnO3 sintered at 1100℃, which has a very large magnetic entropy change ΔSM=3.76J/kg·K under the magnetic field H=1.0T. The phenomenon of large magnetic entropy change, high Curie temperature, high electrical resistivity and high chemical stability make this material a suitable candidates for refrigerants at high temperature.

Both temporally and spectrally resolved fine structures of 90° lateral (3/2)ω0 harmonic emission were experimentally observed. The existence of (3/2)ω0 harmonic filaments is attributed to formation from the moving filament bottom at its transient nc/4 surface. The double hump structure with its intense red hump of laterally emitted (3/2)ω0 spectrum can also be explained by a Doppler correction in addition to the thermal correction. Estimation of both red and blue spectral shifts with our simple model is qualitatively consistent with experimental results. Experiments showed that the (3/2)ω0 emission was evidently suppressed by using a broad band laser. This may be promising for superhot electron suppression.

We present preliminary studies of the laser-imploded glass microballons by our newly developed multi-frame x-ray shadowgraphy which is in good agreement with our simulation calculation. The study shows that uniform illumination is an important factor for good implosions.

We studied a phenomena of spontaneous current generated from laser plasma, which was produced from several plane target made from Rh, Ag and Cu irradiated with high power laser light. The pulse-width, output energy and wavelength of the laser were 200 ps (FWHM), 0.1-4J and 1.06 μm. respectively. At the focus spot of the target irradiated with laser, a spontaneous current density as high as 107A/cm2 was found in the experiment.

The characteristics of neutron emissions from leser-plasmas have been studied. Targets in the form of plane and spherical pellet were made of thermonuclear material containing deuterium, and irradiated by single beam laser system with pulse duration of the order of ns and six-beam laser systems with pulse duration of the order of ns and sns respectively.

We have studied the interaction between the 1010 W Nd glass laser pulses with a leading edge of about 1ns and several planar targets made of deuterium-contained materials. In our experiments, the neutron yields, electron temperature and various characteristics (such as reflectivity, temporal, spatial and spectral structure) of the backward-reflected laser light from the plasmas have been mainly measured.

Both temporally and Spectrally resolved fine structures of 90° lateral 3/2ω0 harmo-nic emission were experimentally observed. The existence of 3/2ω0 harmonic filaments isattributed to the 3/2ω0 harmonic radiation emitted from neighborhood of the bottom ofmoving filament, about nc/4 away from it. The double hump structure with intensered hump of laterally emitted 3/2ω0 spectrum can also be explained by Doppler correc-tion besides the thermal correction due to fast moving TPD process occuring in the unstable filaments. Estimation of both red and blue shifts using our simple model is wellconsistent with experimental results. Experiments showed that the 3/2ω0 emission wasobviously suppressed by using broad band laser owing to more uniform illumination on the target surface and broad band effect. These may be promissing for superhot electron suppression.