A novel into-plane rotating rnicromirror actuated by a hybrid electrostatic driving structure is presented. The hybrid driving structure is made up of a planar plate drive and a vertical comb drive. The device is fabr...A novel into-plane rotating rnicromirror actuated by a hybrid electrostatic driving structure is presented. The hybrid driving structure is made up of a planar plate drive and a vertical comb drive. The device is fabricated in SOI substrate by using a bulk-and-surface mixed silicon micromachining process. As demonstrated by experiment, the novel driving structure can actuate the mirror to achieve large-range continuous rotation as well as spontaneous 90°rotation induced by the pull-in effect. The continuous rotating range of the micromirror is increased to about 46° at an increased yielding voltage. The measured yielding voltages of the mirrors with torsional springs of 1 and 0.5μm in thickness are 390 - 410V and 140 - 160V, respectively. The optical insertion loss has also been measured to be --1.98dB when the mirror serves as an optical switch.展开更多
破碎生产线在建设设计时选用熟料散装机进行放料,由于产品物料粒度为0~80 m m,在实际工作时经常发生钢丝绳错位、伸缩布套运作不灵敏等问题,降低了发料速度,增加了损耗。为解决这一系列问题,采取料仓下料处垂直压力分析法,校核所需推力...破碎生产线在建设设计时选用熟料散装机进行放料,由于产品物料粒度为0~80 m m,在实际工作时经常发生钢丝绳错位、伸缩布套运作不灵敏等问题,降低了发料速度,增加了损耗。为解决这一系列问题,采取料仓下料处垂直压力分析法,校核所需推力,选取合适的固定螺栓,并依据各项计算数据,选取以液压驱动的电液推杆平板阀,在实际运转中起到了良好的作用,对石灰石放料装置的选择具有一定的借鉴意义。展开更多
This paper presents an experimental study including visualization on a flat plate closed loop pulsating heat pipes.It consists of a total of 40 channels with square cross section(2 mm×2 mm,165 mm long) machined d...This paper presents an experimental study including visualization on a flat plate closed loop pulsating heat pipes.It consists of a total of 40 channels with square cross section(2 mm×2 mm,165 mm long) machined directly on an aluminum plate(180 mm×120 mm×3 mm) covered by a transparent plate.The working fluid employed is ethanol.As a result,various flow patterns and their transitions are observed and found to be related to the fluid fill ratio,input heat load and the device orientation.Also the operational characteristics and working mechanism are discussed.展开更多
This paper presents an experimental study on a flat plate closed loop pulsating heat pipes. It consisted of total 40 channels with square cross section （2 × 2 mm^2, 165 mm long） machined directly on an aluminum...This paper presents an experimental study on a flat plate closed loop pulsating heat pipes. It consisted of total 40 channels with square cross section （2 × 2 mm^2, 165 mm long） machined directly on an aluminum plate（180×120×3 nm^2）, which was covered by a transparent plate. The working fluid employed was ethanol. As the results, the influence parameters of thermal performance were investigated, such as filling ratio, heat load and operational orientations etc. Filling ratio was found to be a critical parameter, and its effect was rather complicated. According to its values the PHP plate could have four distinct working zones with different operational characteristics and heat transfer performance. The effect of heat load on thermal performance was found to be positive, and in general, iucrcasing the heat load would improve heat transfer performance. In order to analyze the effect of gravity on thermal performance, three different heat modes and total seven tilt angles were tested and compared. Successful operation at all orientations with respect to gravity was also achieved.展开更多
Based on the principle of turned mass damper(TMD) systems,the conceptual design of semi-submersible platform with a moveable heave-plate(MHS) has been put forward.The heave motion response amplitude operator(RAO) and ...Based on the principle of turned mass damper(TMD) systems,the conceptual design of semi-submersible platform with a moveable heave-plate(MHS) has been put forward.The heave motion response amplitude operator(RAO) and viscous damping of the MHS platform are calculated by iteration,and the coupling stiffness between the MHS hull and the heave-plate is optimized to decrease the maximum heave motion response of the MHS hull under 10-year survival conditions in the South China Sea.The nu-merical results indicate that the heave motion RAO of the MHS hull can be decreased in the range of predominant wave frequencies,which may provide some reference to the heave motion control of offshore platforms.展开更多
Different methods to detect boundary layer transition are investigated within the scope of this paper. Laminar and turbulent boundary layers exhibit a significantly different behavior, not only regarding skin friction...Different methods to detect boundary layer transition are investigated within the scope of this paper. Laminar and turbulent boundary layers exhibit a significantly different behavior, not only regarding skin friction but also for heat-transfer which affects the blade cooling design. The present work presents a novel and non-intrusive measurement technique to detect the transition, based on acoustic concepts. The reliability of the technique was investigated by means of boundary layer measurements over a fiat plate in subsonic flow conditions. After a preliminary assessment with a conventional Preston tube, a row of microphones were installed along the plate to correlate transition pressure fluctuations. To provide a comprehensive representation of the experiment, dedicated measurements with a fast response aerodynamic pressure probe were performed to determine the turbulence intensity and the dissipation rate upstream of the flat plate. The experimental results were systematically compared with calculations performed with three different computational fluid dynamics solvers （ANSYS-Fluent, ANSYS-CFX, OpenFOAM） and using both the k-k1-ω and the γ-Reθ transition models. Results show a fair agreement between CFD （computational fluid dynamics） predictions and the acoustic technique, suggesting that this latter might represent an interesting alternative option for transition measurements.展开更多
The high-precision GPS data observed from the northeast margin of the Qinghai-Xizang （Tibet） block and the Sichuan-Yunnan GPS monitoring areas in 1991 （1993）, 1999 and 2001 revealed that： before the Kunlun earthq...The high-precision GPS data observed from the northeast margin of the Qinghai-Xizang （Tibet） block and the Sichuan-Yunnan GPS monitoring areas in 1991 （1993）, 1999 and 2001 revealed that： before the Kunlun earthquake with Ms =8.1 on November 14, 2001, the dynamic variation features of horizontal movement-deformation field in the north and east marginal tectonic areas of the Qinghai-Xizang （Tibet） block had some correlated features. That is to say, under the general background of inherited movement, the movement intensifies in the two areas weakened synchronously and the state of deformation changed when the great earthquake was impending. Analysis and study in connection with geological structures showed that before the Kunlun Ms8.1 earthquake, the correlated variations of movement-deformation on the boundaries of Qinghai-Xizang （Tibet） block were related to the disturbing stress field caused by the extensive and rapid stress-strain accumulation in the late stage of large earthquake preparation. Owing to the occurrence of large earthquake inside the block, the release of large amount of strain energy, and the adjustment of tectonic stress field, in relevant structural positions （especially zones not penetrated by historical strong earthquake ruptures） in boundary zones where larger amount of strain energy was accumulated, stress-strain may be further accumulated or else released through rupture.展开更多
Temperature distribution over the absorber plate of a parallel flow flat-plate solar collector is numerically analyzed. The governing differential equations with boundary conditions are solved numerically using fluent...Temperature distribution over the absorber plate of a parallel flow flat-plate solar collector is numerically analyzed. The governing differential equations with boundary conditions are solved numerically using fluent software. Effects of the inlet mass flux, inlet temperature and tube spacing on velocity and temperature distributions are discussed. Numerical results show that the distributions of velocity and temperature of fluid is unsymmetrical inside pipe.展开更多
文摘A novel into-plane rotating rnicromirror actuated by a hybrid electrostatic driving structure is presented. The hybrid driving structure is made up of a planar plate drive and a vertical comb drive. The device is fabricated in SOI substrate by using a bulk-and-surface mixed silicon micromachining process. As demonstrated by experiment, the novel driving structure can actuate the mirror to achieve large-range continuous rotation as well as spontaneous 90°rotation induced by the pull-in effect. The continuous rotating range of the micromirror is increased to about 46° at an increased yielding voltage. The measured yielding voltages of the mirrors with torsional springs of 1 and 0.5μm in thickness are 390 - 410V and 140 - 160V, respectively. The optical insertion loss has also been measured to be --1.98dB when the mirror serves as an optical switch.
文摘破碎生产线在建设设计时选用熟料散装机进行放料,由于产品物料粒度为0~80 m m,在实际工作时经常发生钢丝绳错位、伸缩布套运作不灵敏等问题,降低了发料速度,增加了损耗。为解决这一系列问题,采取料仓下料处垂直压力分析法,校核所需推力,选取合适的固定螺栓,并依据各项计算数据,选取以液压驱动的电液推杆平板阀,在实际运转中起到了良好的作用,对石灰石放料装置的选择具有一定的借鉴意义。
基金the Ger man National Science Foundation (GR-412/33-2)Shanghai Leading Academic Discipline Project (No.B604)
文摘This paper presents an experimental study including visualization on a flat plate closed loop pulsating heat pipes.It consists of a total of 40 channels with square cross section(2 mm×2 mm,165 mm long) machined directly on an aluminum plate(180 mm×120 mm×3 mm) covered by a transparent plate.The working fluid employed is ethanol.As a result,various flow patterns and their transitions are observed and found to be related to the fluid fill ratio,input heat load and the device orientation.Also the operational characteristics and working mechanism are discussed.
基金Supported by the Ger man National Science Foundation (DFG)(No. GR412/33)
文摘This paper presents an experimental study on a flat plate closed loop pulsating heat pipes. It consisted of total 40 channels with square cross section （2 × 2 mm^2, 165 mm long） machined directly on an aluminum plate（180×120×3 nm^2）, which was covered by a transparent plate. The working fluid employed was ethanol. As the results, the influence parameters of thermal performance were investigated, such as filling ratio, heat load and operational orientations etc. Filling ratio was found to be a critical parameter, and its effect was rather complicated. According to its values the PHP plate could have four distinct working zones with different operational characteristics and heat transfer performance. The effect of heat load on thermal performance was found to be positive, and in general, iucrcasing the heat load would improve heat transfer performance. In order to analyze the effect of gravity on thermal performance, three different heat modes and total seven tilt angles were tested and compared. Successful operation at all orientations with respect to gravity was also achieved.
基金supported by the National Basic Research Program of China (No. 2011CB013702)
文摘Based on the principle of turned mass damper(TMD) systems,the conceptual design of semi-submersible platform with a moveable heave-plate(MHS) has been put forward.The heave motion response amplitude operator(RAO) and viscous damping of the MHS platform are calculated by iteration,and the coupling stiffness between the MHS hull and the heave-plate is optimized to decrease the maximum heave motion response of the MHS hull under 10-year survival conditions in the South China Sea.The nu-merical results indicate that the heave motion RAO of the MHS hull can be decreased in the range of predominant wave frequencies,which may provide some reference to the heave motion control of offshore platforms.
文摘Different methods to detect boundary layer transition are investigated within the scope of this paper. Laminar and turbulent boundary layers exhibit a significantly different behavior, not only regarding skin friction but also for heat-transfer which affects the blade cooling design. The present work presents a novel and non-intrusive measurement technique to detect the transition, based on acoustic concepts. The reliability of the technique was investigated by means of boundary layer measurements over a fiat plate in subsonic flow conditions. After a preliminary assessment with a conventional Preston tube, a row of microphones were installed along the plate to correlate transition pressure fluctuations. To provide a comprehensive representation of the experiment, dedicated measurements with a fast response aerodynamic pressure probe were performed to determine the turbulence intensity and the dissipation rate upstream of the flat plate. The experimental results were systematically compared with calculations performed with three different computational fluid dynamics solvers （ANSYS-Fluent, ANSYS-CFX, OpenFOAM） and using both the k-k1-ω and the γ-Reθ transition models. Results show a fair agreement between CFD （computational fluid dynamics） predictions and the acoustic technique, suggesting that this latter might represent an interesting alternative option for transition measurements.
文摘The high-precision GPS data observed from the northeast margin of the Qinghai-Xizang （Tibet） block and the Sichuan-Yunnan GPS monitoring areas in 1991 （1993）, 1999 and 2001 revealed that： before the Kunlun earthquake with Ms =8.1 on November 14, 2001, the dynamic variation features of horizontal movement-deformation field in the north and east marginal tectonic areas of the Qinghai-Xizang （Tibet） block had some correlated features. That is to say, under the general background of inherited movement, the movement intensifies in the two areas weakened synchronously and the state of deformation changed when the great earthquake was impending. Analysis and study in connection with geological structures showed that before the Kunlun Ms8.1 earthquake, the correlated variations of movement-deformation on the boundaries of Qinghai-Xizang （Tibet） block were related to the disturbing stress field caused by the extensive and rapid stress-strain accumulation in the late stage of large earthquake preparation. Owing to the occurrence of large earthquake inside the block, the release of large amount of strain energy, and the adjustment of tectonic stress field, in relevant structural positions （especially zones not penetrated by historical strong earthquake ruptures） in boundary zones where larger amount of strain energy was accumulated, stress-strain may be further accumulated or else released through rupture.
文摘Temperature distribution over the absorber plate of a parallel flow flat-plate solar collector is numerically analyzed. The governing differential equations with boundary conditions are solved numerically using fluent software. Effects of the inlet mass flux, inlet temperature and tube spacing on velocity and temperature distributions are discussed. Numerical results show that the distributions of velocity and temperature of fluid is unsymmetrical inside pipe.
