The characteristics of thickness enhancement fact or and bandgap wavelength of selectively grown InGaAsP are investigated.A high thi ckness enhancement factor of 2.9 is obtained.Spotsize converter integrated DFB las...The characteristics of thickness enhancement fact or and bandgap wavelength of selectively grown InGaAsP are investigated.A high thi ckness enhancement factor of 2.9 is obtained.Spotsize converter integrated DFB lasers are fabricated by using the technique of SAG.The threshold current is as low as 10.8mA.The output power is 10mW at 60mA without coating and the SMSR is 35.8dB.The vertical far field angle (FWHM) is decreased from 34° to 9°.The to lerance of 1dBm misalignment is 3.4μm vertically.展开更多
This paper reports on the design,fabrication,and performance of an integrated electro-absorptive modulated laser based on butt-joint configuration for 10Gbit/s application.This paper mainly aims at two aspects.One is ...This paper reports on the design,fabrication,and performance of an integrated electro-absorptive modulated laser based on butt-joint configuration for 10Gbit/s application.This paper mainly aims at two aspects.One is to improve the optical coupling between the laser and modulator;another is to increase the bandwidth of such devices by reducing the capacitance parameter of the modulator.The integrated devices exhibit high static and dynamic characteristics. Typical threshold current is 15mA,with some value as low as 8mA.Output power at 100mA is more than 10mW.The extinction characteristics,modulation bandwidth,and electrical return loss are measured.3dB bandwidth more than 10GHz is monitored.展开更多
For the modified demodulation arithmetic of 3×3 coupler, the processing software built on the basis of Labview is able to demodulate asymmetric 3×3 coupler signal and do further spectrum analysis. It shows t...For the modified demodulation arithmetic of 3×3 coupler, the processing software built on the basis of Labview is able to demodulate asymmetric 3×3 coupler signal and do further spectrum analysis. It shows that the measured frequency ranges from 10 Hz to 1 000 Hz and phase range is covered by -10 rad^10 rad. The phase sensitivity is 0.5 V/rad. This system is proved to show high resolution and wide dynamic range.展开更多
Contact reactions of guide surfaces of assembly interfaces lead to the decreasing of theirs lateral and angular misalignments. The focus of this paper is the development of algorithms for computation of guide surfaces...Contact reactions of guide surfaces of assembly interfaces lead to the decreasing of theirs lateral and angular misalignments. The focus of this paper is the development of algorithms for computation of guide surfaces contact forces with acceptable engineering accuracy for real time simulation of assembly operations. Therefore, each complex guide surface is described as a set of contacting elements. Each contacting element for one＇s part can be represented by a finite set of geometric primitives which geometry is described by low order algebraic equations. So contact conditions and geometric parameters for all pairs of primitives are determined by analytical expressions. Math models are developed for two classes of contact interaction. The first class includes all cases when each contacting surface has several degrees of freedom of motion. Therefore, contact reactions introduced into differential equations of motion are calculated by using contacting elements penetrations, stiffness and damping parameters. The second class corresponds to all cases when one of contacting surfaces has insignificant inertia and only one degree of freedom of relative displacement counteracted by a spring. Here contact reactions are calculated from spring tension with any practical accuracy. This is very useful in some practical applications. Presented algorithms provide real time simulation together with some approaches for reduction of redundant comnutations.展开更多
A simple autonomous docking method based on infrared sensors for mobile self-reconfigurable relay microrobots is proposed in the paper.The IR guidance system composed of an IR receiver and four IR emitters is designed...A simple autonomous docking method based on infrared sensors for mobile self-reconfigurable relay microrobots is proposed in the paper.The IR guidance system composed of an IR receiver and four IR emitters is designed,analyzed and developed.The autonomous docking control method based on centering alignment and dynamic motion planning is adopted so that it has high efficiency and reliability.Two basic microrobot prototypes are developed,and related docking experiments are done to verify the feasibility of the approach.展开更多
Realistic 3D-animation is used in all motion simulation systems of mechanisms and other mechanicals systems. It provides a high-quality illustration of time processes, but it has a weak capability for analysis of thei...Realistic 3D-animation is used in all motion simulation systems of mechanisms and other mechanicals systems. It provides a high-quality illustration of time processes, but it has a weak capability for analysis of their dynamics, for simultaneous display of contact interaction and functioning of mechanisms of different motion types. A spacecraft docking is characterized by a complex contact interaction of docking assemblies with mechanisms and devices of different motion types. Integration and time synchronization of the animation, plots and numerical values greatly facilitates the understanding of dynamics features of these processes. Usage of simple wireframe graphical models allows displaying all contact points. A changing of the set of graphical elements focuses attention on major events of a simulated process. Graphical models developed with consideration of these features and used for spacecraft docking simulation analysis are called dynamic diagrams and described in this paper.展开更多
Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters inclu...Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters including rotor speed and continuous and dispersed phase velocities on the volumetric overall mass transfer coefficients are investigated. The results show that the mass transfer performance is strongly dependent on agitation rate and interfacial tension, but only slightly dependent on phase flow rates. In this study, effective diffusivity is used instead of molecular diffusivity in the Grober equation for estimation of dispersed phase overall mass transfer coefficient.The enhancement factor is determined experimentally and there from an empirical expression is derived for prediction of the enhancement factor as a function of Reynolds number. The predicted results compared to the experimental data show that the proposed correlation can efficiently predict the overall mass transfer coefficients in asymmetric rotating disk contactors.展开更多
A novel hybrid self-reconfigurable modular robot is designed to finish the morphing action from line shape to hexagon shape. The robot is composed of many basic modules,each of which consists of a master module and a ...A novel hybrid self-reconfigurable modular robot is designed to finish the morphing action from line shape to hexagon shape. The robot is composed of many basic modules,each of which consists of a master module and a slave module in the shape of triangular prism. There are four connection ports on each basic module. For the master module there are two holes on each connection port,and for the slave one there are two pegs on each connection. The docking process between two neighboring basic modules is analyzed with a peg-in-hole mechanical structure. A small motion's method is presented and the contact forces are derived. According to the force/moment,the pose of a motion module should be adjusted to make two neighboring modules align and finish the docking process.Finally,a simulation of 3 basic modules is shown to finish the morphing and docking process effectively. The system can finish the morphing task from the line shape to the hexagon shape.展开更多
Adjacent treatment fields are commonly employed in external beam radiation therapy, such as the mantle and inverted-Y fields for the treatment of Hodgkin's disease. In some cases, the adjacent fields are orthogona...Adjacent treatment fields are commonly employed in external beam radiation therapy, such as the mantle and inverted-Y fields for the treatment of Hodgkin's disease. In some cases, the adjacent fields are orthogonal, such as the craniospinal fields used in the treatment of medulloblastoma. Another example is the irradiation of head and neck tumors when the lateral neck fields are placed adjacent to the anterior supraclavicular field. In each of these situations, there is a possibility of introducing very large dosage errors across the junction. Consequently, this region is at risk for tumor recurrence if it is underdosed or severe complications if it is overdosed. Four millimeter overlap and gap resulted in an unacceptable dose in homogeneity in the junction. As a result of this study, the magnitudes of hot and cold spots might be clinically acceptable for 3 mm gap between photon fields.展开更多
文摘The characteristics of thickness enhancement fact or and bandgap wavelength of selectively grown InGaAsP are investigated.A high thi ckness enhancement factor of 2.9 is obtained.Spotsize converter integrated DFB lasers are fabricated by using the technique of SAG.The threshold current is as low as 10.8mA.The output power is 10mW at 60mA without coating and the SMSR is 35.8dB.The vertical far field angle (FWHM) is decreased from 34° to 9°.The to lerance of 1dBm misalignment is 3.4μm vertically.
文摘This paper reports on the design,fabrication,and performance of an integrated electro-absorptive modulated laser based on butt-joint configuration for 10Gbit/s application.This paper mainly aims at two aspects.One is to improve the optical coupling between the laser and modulator;another is to increase the bandwidth of such devices by reducing the capacitance parameter of the modulator.The integrated devices exhibit high static and dynamic characteristics. Typical threshold current is 15mA,with some value as low as 8mA.Output power at 100mA is more than 10mW.The extinction characteristics,modulation bandwidth,and electrical return loss are measured.3dB bandwidth more than 10GHz is monitored.
文摘For the modified demodulation arithmetic of 3×3 coupler, the processing software built on the basis of Labview is able to demodulate asymmetric 3×3 coupler signal and do further spectrum analysis. It shows that the measured frequency ranges from 10 Hz to 1 000 Hz and phase range is covered by -10 rad^10 rad. The phase sensitivity is 0.5 V/rad. This system is proved to show high resolution and wide dynamic range.
文摘Contact reactions of guide surfaces of assembly interfaces lead to the decreasing of theirs lateral and angular misalignments. The focus of this paper is the development of algorithms for computation of guide surfaces contact forces with acceptable engineering accuracy for real time simulation of assembly operations. Therefore, each complex guide surface is described as a set of contacting elements. Each contacting element for one＇s part can be represented by a finite set of geometric primitives which geometry is described by low order algebraic equations. So contact conditions and geometric parameters for all pairs of primitives are determined by analytical expressions. Math models are developed for two classes of contact interaction. The first class includes all cases when each contacting surface has several degrees of freedom of motion. Therefore, contact reactions introduced into differential equations of motion are calculated by using contacting elements penetrations, stiffness and damping parameters. The second class corresponds to all cases when one of contacting surfaces has insignificant inertia and only one degree of freedom of relative displacement counteracted by a spring. Here contact reactions are calculated from spring tension with any practical accuracy. This is very useful in some practical applications. Presented algorithms provide real time simulation together with some approaches for reduction of redundant comnutations.
基金Supported by the National High Technology Research and Development Programme of China(No.2007AA04Z340)
文摘A simple autonomous docking method based on infrared sensors for mobile self-reconfigurable relay microrobots is proposed in the paper.The IR guidance system composed of an IR receiver and four IR emitters is designed,analyzed and developed.The autonomous docking control method based on centering alignment and dynamic motion planning is adopted so that it has high efficiency and reliability.Two basic microrobot prototypes are developed,and related docking experiments are done to verify the feasibility of the approach.
文摘Realistic 3D-animation is used in all motion simulation systems of mechanisms and other mechanicals systems. It provides a high-quality illustration of time processes, but it has a weak capability for analysis of their dynamics, for simultaneous display of contact interaction and functioning of mechanisms of different motion types. A spacecraft docking is characterized by a complex contact interaction of docking assemblies with mechanisms and devices of different motion types. Integration and time synchronization of the animation, plots and numerical values greatly facilitates the understanding of dynamics features of these processes. Usage of simple wireframe graphical models allows displaying all contact points. A changing of the set of graphical elements focuses attention on major events of a simulated process. Graphical models developed with consideration of these features and used for spacecraft docking simulation analysis are called dynamic diagrams and described in this paper.
文摘Mass transfer characteristics have been investigated in a 113 mm diameter asymmetric rotating disk contactor of the pilot plant scale for two different liquid–liquid systems. The effects of operating parameters including rotor speed and continuous and dispersed phase velocities on the volumetric overall mass transfer coefficients are investigated. The results show that the mass transfer performance is strongly dependent on agitation rate and interfacial tension, but only slightly dependent on phase flow rates. In this study, effective diffusivity is used instead of molecular diffusivity in the Grober equation for estimation of dispersed phase overall mass transfer coefficient.The enhancement factor is determined experimentally and there from an empirical expression is derived for prediction of the enhancement factor as a function of Reynolds number. The predicted results compared to the experimental data show that the proposed correlation can efficiently predict the overall mass transfer coefficients in asymmetric rotating disk contactors.
基金Supported by the National Natural Science Foundation of China(No.61175069,51075272,51475300)
文摘A novel hybrid self-reconfigurable modular robot is designed to finish the morphing action from line shape to hexagon shape. The robot is composed of many basic modules,each of which consists of a master module and a slave module in the shape of triangular prism. There are four connection ports on each basic module. For the master module there are two holes on each connection port,and for the slave one there are two pegs on each connection. The docking process between two neighboring basic modules is analyzed with a peg-in-hole mechanical structure. A small motion's method is presented and the contact forces are derived. According to the force/moment,the pose of a motion module should be adjusted to make two neighboring modules align and finish the docking process.Finally,a simulation of 3 basic modules is shown to finish the morphing and docking process effectively. The system can finish the morphing task from the line shape to the hexagon shape.
文摘Adjacent treatment fields are commonly employed in external beam radiation therapy, such as the mantle and inverted-Y fields for the treatment of Hodgkin's disease. In some cases, the adjacent fields are orthogonal, such as the craniospinal fields used in the treatment of medulloblastoma. Another example is the irradiation of head and neck tumors when the lateral neck fields are placed adjacent to the anterior supraclavicular field. In each of these situations, there is a possibility of introducing very large dosage errors across the junction. Consequently, this region is at risk for tumor recurrence if it is underdosed or severe complications if it is overdosed. Four millimeter overlap and gap resulted in an unacceptable dose in homogeneity in the junction. As a result of this study, the magnitudes of hot and cold spots might be clinically acceptable for 3 mm gap between photon fields.
