This paper reports a Study carried out to substantiate or refute the belief that when coolant is applied, the cutting performance is actually improved. Experiments on cutting forces and chip geometry were conducted in...This paper reports a Study carried out to substantiate or refute the belief that when coolant is applied, the cutting performance is actually improved. Experiments on cutting forces and chip geometry were conducted in which AISI 1050 Steel was machined by turning using P30 uncoated tungsten carbide tools. Experiments were performed on a CNC Okuma LH35-N lathe undermachining conditions commonly used in workshops in Singapore and many other parts of the world.展开更多
We present a systematic analysis of the exciton-recombination zone within all-quantum-dot （QD） multilayer films using sensing QD layers in QD-based light-emitting diodes （QLEDs）, and demonstrate the a11-QD multila...We present a systematic analysis of the exciton-recombination zone within all-quantum-dot （QD） multilayer films using sensing QD layers in QD-based light-emitting diodes （QLEDs）, and demonstrate the a11-QD multilayer films with different sequences of layers prepared by inserting a sensing blue QD layer denoted as B at various positions within four red QD multilayers denoted as R. We also use different hole transporting layers （PVK, CBP as well as poly-TPD） to prevent the formation of leakage current and to improve the luminance. The results show that the total EL emission is mostly at the fourth （60%） and fifth （40%） QD monolayers, adjacent to ITO. This presents both decreasing current density and increasing brightness with different hole transporting layers, thus resulting in more efficient performance.展开更多
Introducing a thin InGaN interlayer with a relatively lower indium content between the quantum well （QW） and barrier results in a step-like InxGa1-xN/GaN potential barrier on one side of the QW. This change in the a...Introducing a thin InGaN interlayer with a relatively lower indium content between the quantum well （QW） and barrier results in a step-like InxGa1-xN/GaN potential barrier on one side of the QW. This change in the active region leads to a significant shift in photolumineseence （PL） and electroluminescence （EL） emissions to a longer wavelength compared with the conventional QW based light-emitting diodes. More importantly, an improvement against efficiency droop and an enhancement in light output power at the high-current injection are observed in the modified light-emitting diode structures. The role of the inserted layer in these improvements is investigated by simulation in detail, which shows that the creation of more sublevels in the valence band and the increase of hole concentration inside QWs are the main reasons for these improvements.展开更多
Experiments have been conducted on a plasma opening switch (POS) test-bed to investigate the influence of cathode materials made of aluminum, stainless steel, molybdenum and tungsten on opening performance for conduct...Experiments have been conducted on a plasma opening switch (POS) test-bed to investigate the influence of cathode materials made of aluminum, stainless steel, molybdenum and tungsten on opening performance for conduction time up to 3 microseconds, conduction current up to 100 kA. Remarkaly different opening characteristics have been shown for these materials,with tungsten being of the best opening performance.展开更多
The semiclassical transport equations are used to study the high frequency performance of AlGaAs / GaAs HBTs. Electron velocity overshoot effect and its influence on the cut off frequency characteristics of AlGaAs / G...The semiclassical transport equations are used to study the high frequency performance of AlGaAs / GaAs HBTs. Electron velocity overshoot effect and its influence on the cut off frequency characteristics of AlGaAs / GaAs HBTs with different collector design parameters are analyzed and discussed.展开更多
We investigate influences of series resistances on the performance of 1.55 μm waveguide-type germanium photodetectors（Ge-PDs） on a silicon-on-insulator substrate. The current-voltage characteristics, responsivities...We investigate influences of series resistances on the performance of 1.55 μm waveguide-type germanium photodetectors（Ge-PDs） on a silicon-on-insulator substrate. The current-voltage characteristics, responsivities,saturation photo-current characteristics, electrical reflection coefficients, and photodetection frequency responses of Ge-PDs, having different series resistances, are measured, and their equivalent circuit models are established. By analyzing the resulting circuit model parameters, we determine how much Ge-PD series resistances influence Ge-PD saturation photo-currents and photodetection bandwidth. These results should be of great use for optimization of Ge-PD fabrication processes and device parameters for target applications.展开更多
Because of the influence of OH groups in phosphate glasses on the radiation of rare-earth ions, the laser performance is degraded. The laser efficiency and the small signal gain experiment of several phosphate glass s...Because of the influence of OH groups in phosphate glasses on the radiation of rare-earth ions, the laser performance is degraded. The laser efficiency and the small signal gain experiment of several phosphate glass samples have been done, the concentration of OH groups in glasses was calculated from the measured absorption coefficient at 3.47 μm. It is shown that the concentration of OH groups in phosphate glasses can seriously influence the laser output characteristics, and the OH groups have worse influence on the laser amplifier than laser oscillator.展开更多
This paper, taking the distance between the piezoelectric ceramic center and the displacement node location of the transducer as a parameter, investigates the relation of characteristic parameters of transducer, such ...This paper, taking the distance between the piezoelectric ceramic center and the displacement node location of the transducer as a parameter, investigates the relation of characteristic parameters of transducer, such as force factor, equivalent resistance, potential maximum electroacoustical efficiency, and loading performance, to the displacement node location. Some design considerations about the selection of node location are noted .展开更多
The influence of GaAs substrate on the transmission performance of a multi-film Fabry-P＇erot filter （FPF）,fabricated by metalorganic chemical vapor deposition epitaxial growth on GaAs substrate,is investigated usin...The influence of GaAs substrate on the transmission performance of a multi-film Fabry-P＇erot filter （FPF）,fabricated by metalorganic chemical vapor deposition epitaxial growth on GaAs substrate,is investigated using the transfer matrix method.On the basis of the theoretical simulation,we determine that the quality of the resonant transmission peak of this epitaxially grown FPF （EG-FPF） deteriorates through splitting when the substrate is taken into account.Rapid periodic oscillation of peak-transmittivity along with the alteration of substrate thickness is also observed in the simulation results.Finally,a remarkably improved transmission performance of the EG-FPF is obtained by thinning the substrate down to a suitable thickness range through well-controlled grinding and polishing.展开更多
文摘This paper reports a Study carried out to substantiate or refute the belief that when coolant is applied, the cutting performance is actually improved. Experiments on cutting forces and chip geometry were conducted in which AISI 1050 Steel was machined by turning using P30 uncoated tungsten carbide tools. Experiments were performed on a CNC Okuma LH35-N lathe undermachining conditions commonly used in workshops in Singapore and many other parts of the world.
基金Supported by the National High Technology Research and Development Program of China under Grant No 2013AA032205the National Natural Science Foundation of China under Grant Nos 11474018,51272022 and 61575019+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant Nos 20120009130005 and 20130009130001the Technological Development Contract under Grant No HETONG-150188-04E008
文摘We present a systematic analysis of the exciton-recombination zone within all-quantum-dot （QD） multilayer films using sensing QD layers in QD-based light-emitting diodes （QLEDs）, and demonstrate the a11-QD multilayer films with different sequences of layers prepared by inserting a sensing blue QD layer denoted as B at various positions within four red QD multilayers denoted as R. We also use different hole transporting layers （PVK, CBP as well as poly-TPD） to prevent the formation of leakage current and to improve the luminance. The results show that the total EL emission is mostly at the fourth （60%） and fifth （40%） QD monolayers, adjacent to ITO. This presents both decreasing current density and increasing brightness with different hole transporting layers, thus resulting in more efficient performance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 61334005,51272008 and 60990314the Beijing Municipal Science and Technology Project under Grant No H030430020000the National Basic Research Program of China under Grant Nos 2012CB619304 and 2012CB619306
文摘Introducing a thin InGaN interlayer with a relatively lower indium content between the quantum well （QW） and barrier results in a step-like InxGa1-xN/GaN potential barrier on one side of the QW. This change in the active region leads to a significant shift in photolumineseence （PL） and electroluminescence （EL） emissions to a longer wavelength compared with the conventional QW based light-emitting diodes. More importantly, an improvement against efficiency droop and an enhancement in light output power at the high-current injection are observed in the modified light-emitting diode structures. The role of the inserted layer in these improvements is investigated by simulation in detail, which shows that the creation of more sublevels in the valence band and the increase of hole concentration inside QWs are the main reasons for these improvements.
文摘Experiments have been conducted on a plasma opening switch (POS) test-bed to investigate the influence of cathode materials made of aluminum, stainless steel, molybdenum and tungsten on opening performance for conduction time up to 3 microseconds, conduction current up to 100 kA. Remarkaly different opening characteristics have been shown for these materials,with tungsten being of the best opening performance.
文摘The semiclassical transport equations are used to study the high frequency performance of AlGaAs / GaAs HBTs. Electron velocity overshoot effect and its influence on the cut off frequency characteristics of AlGaAs / GaAs HBTs with different collector design parameters are analyzed and discussed.
基金supported in part by the National Research Foundation of Korea through the Korean Ministry of Science,ICTFuture Planning under Grant No.2015R1A2A2A01007772in part by the Materials and Parts Technology Research and Development Program through the Korean Ministry of Trade,Industry & Energy under Project No.10065666
文摘We investigate influences of series resistances on the performance of 1.55 μm waveguide-type germanium photodetectors（Ge-PDs） on a silicon-on-insulator substrate. The current-voltage characteristics, responsivities,saturation photo-current characteristics, electrical reflection coefficients, and photodetection frequency responses of Ge-PDs, having different series resistances, are measured, and their equivalent circuit models are established. By analyzing the resulting circuit model parameters, we determine how much Ge-PD series resistances influence Ge-PD saturation photo-currents and photodetection bandwidth. These results should be of great use for optimization of Ge-PD fabrication processes and device parameters for target applications.
文摘Because of the influence of OH groups in phosphate glasses on the radiation of rare-earth ions, the laser performance is degraded. The laser efficiency and the small signal gain experiment of several phosphate glass samples have been done, the concentration of OH groups in glasses was calculated from the measured absorption coefficient at 3.47 μm. It is shown that the concentration of OH groups in phosphate glasses can seriously influence the laser output characteristics, and the OH groups have worse influence on the laser amplifier than laser oscillator.
文摘This paper, taking the distance between the piezoelectric ceramic center and the displacement node location of the transducer as a parameter, investigates the relation of characteristic parameters of transducer, such as force factor, equivalent resistance, potential maximum electroacoustical efficiency, and loading performance, to the displacement node location. Some design considerations about the selection of node location are noted .
基金supported by the National "973" Program of China (No. 2010CB327600)the National "863" Program of China (No. 2007AA03Z418)+3 种基金the Program for Changjiang Scholars and Innovative Research Team in University (No. IRT0609)the Fundamental Research Funds for the Central University (No. BUPT2011RC0403)the National Natural Science Foundation of China (No. 61020106007)the "111" Project of China (No. B07005)
文摘The influence of GaAs substrate on the transmission performance of a multi-film Fabry-P＇erot filter （FPF）,fabricated by metalorganic chemical vapor deposition epitaxial growth on GaAs substrate,is investigated using the transfer matrix method.On the basis of the theoretical simulation,we determine that the quality of the resonant transmission peak of this epitaxially grown FPF （EG-FPF） deteriorates through splitting when the substrate is taken into account.Rapid periodic oscillation of peak-transmittivity along with the alteration of substrate thickness is also observed in the simulation results.Finally,a remarkably improved transmission performance of the EG-FPF is obtained by thinning the substrate down to a suitable thickness range through well-controlled grinding and polishing.
