To improve the wettability of common filler metals on Al metal matrix composites (A1-MMCs), three kinds of active ternary filler metals, Al-Si-Ti, Zn-Al-Ti and Cu-AL-Ti systems, were prepared by the addition of Ti. Ex...
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To improve the wettability of common filler metals on Al metal matrix composites (A1-MMCs), three kinds of active ternary filler metals, Al-Si-Ti, Zn-Al-Ti and Cu-AL-Ti systems, were prepared by the addition of Ti. Excessive melting temperature made the gravity segregation of Ti remarkable in ingot. The effect of Ti content on the melting point for Al-Si-Ti ternary system was not as sensitive as that for Al-Ti binary system. The Al-12Si-1Ti filler metal showed good abiliy to form brazing foil during rapid cooling, ductile fracture surface and similar shear strength to conventional Al-12Si filler metal. Moreover, the Al2O3 reinforcements on initial surface could be covered by the Al-12Si-1 Ti filler metal without irnterfacial gaps after sessile drop test. For 2n-9.5A/-0.5Ti braze alloy, severe vaporization of Zn and severe segregation of Ti occurred. During wettability test for traditional Al-12Si and 2n-9.5Al-0.5Ti, although some Si or Zn, could penetrate into the composite, interfacial gap still remained. The prepared Cu-19Al-1 Ti interlayer consisted of pri,mary phase of Al4Cu9 and network Cu-AI-Ti temary intermetallic conzpound, showing poor ability to form foil and very brittle nature. These results demonstrated that Al-Si-Ti system should be promising for Al-MMCs.
We experimentally demonstrate the C-band wavelength conversion using four-wave mixing in a 17-mm-long silicon-on-insulator waveguide pumped by a dispersed mode-locked femtosecond laser pulse. The idler can be observed...
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We experimentally demonstrate the C-band wavelength conversion using four-wave mixing in a 17-mm-long silicon-on-insulator waveguide pumped by a dispersed mode-locked femtosecond laser pulse. The idler can be observed with an incident average pump power lower than 4 dBm, and about 35 nm of conversion bandwidth from 1530nm to 1565nm is measured by using a 1550-nm pump wavelength. The pulse-pumped efficiency is demonstrated to be higher, by more than 22 dB, than the cw-pumped efficiency. The conversion efficiency variations with respect to the pump and signal powers are also investigated.
We present a novel microwave photonic down-conversion system based on a wideband tunable optoelectronic oscillator. Microwave signals from 14.8 to 31.0 GHz are down-converted to 1 GHz successfully. The conversion gain...
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A low-complexity and single-stage carrier phase recovery algorithm is presented for 16 quadrature-amplitude-modulation coherent optical transmission systems. It is shown that the algorithm achieves better performance ...
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Faster-than-Nyquist (FTN) signaling is discussed both theoretically and experimentally. Several schemes of FTN signal generation and reception are compared with emphasize on high-speed transmission with 16-QAM format....
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A wideband tunable optoelectronic oscillator (OEO) based on stimulated Brillouin scattering is presented in this paper. Microwave signals generation range from 10.98 GHz to 39.98 GHz is demonstrated successfully in ou...
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To avoid the existence of nonlinear and strong coupling in parallel mechanisms,it is necessary to address special care to the type synthesis of mechanisms,especially for the type synthesis of fully-decoupled parallel ...
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To avoid the existence of nonlinear and strong coupling in parallel mechanisms,it is necessary to address special care to the type synthesis of mechanisms,especially for the type synthesis of fully-decoupled parallel mechanisms. Based on the screw theory and the driven-chain principle,a methodology of structural synthesis for fully-decoupled three-rotational( 3R) and two-translational( 2T)parallel mechanisms was proposed by analyzing the characteristics of the input-output relations for fully-decoupled parallel ***,according to the desired kinematic characteristics of fullydecoupled parallel mechanisms,a method was presented by virtue of screw theory to synthesize the desired forms for both the direct and the inverse Jacobian matrices. Secondly,according to the feature of the direct and the inverse Jacobian matrices,the effective screws,the actuated screws and the mobile un-actuated screws of each leg were established based on the reciprocal screw theory and all possible topology structures fulfilling the requirements were ***,the desired fully-decoupled parallel mechanisms could be synthesized by using the structural synthesis rule and structural synthesis of fully-decoupled 3R2 T parallel mechanisms could be obtained exploiting the abovementioned methodology. Furthermore,the Jacobian matrix of a synthesized 3R2 T parallel mechanism was deduced to demonstrate the decoupling feature of the parallel mechanism,which also validated the correctness of the methodology of the type synthesis for fully-decoupled 3R2 T parallel mechanisms.
The time and frequency forced responses for the permanent magnetic planetary gear drive were computed and analyzed. The influence of magnetization intensity and pole pair number to frequency forced responses is discus...
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The sub-Doppler absorption laser spectroscopy at 728nm transition from the 5D5/2 state to the 6F state of cesium with linewidth near 10 MHz is first experimentally performed with indirect pumping from the ground state...
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The sub-Doppler absorption laser spectroscopy at 728nm transition from the 5D5/2 state to the 6F state of cesium with linewidth near 10 MHz is first experimentally performed with indirect pumping from the ground state 6S1/2 to the state 7P3/2 by a 455.5nm diode laser. Using a 455.5nm diode laser as an indirect pump laser, several excited states will be populated due to spontaneous decay from the 7P state. We first implement the sub-Doppler absorption laser spectroscopy at 728nm from the 5D5/2 state to the 6F state when Cs atoms within thermal glass cell decay to the 5D5/2 state. Due to velocity transfer effect, the hyperfine structure of 5D5/2 shows a mixed and complicated pattern but very e/ear structure when the 455.5nm pumping laser is counter-propagating （or co-propagating） with the 728nm probing laser.
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