Polishing plays an indispensable role in optical processing, especially for large-aperture optical reflective mirrors with freeform surfaces. Robotic polishing requires effective control of the ...contact force between the robot and the mirror during processing. In order to maintain a constant contact force during polishing, traditional polishing robots rely on closed-loop control of air cylinders, whose performances heavily rely on high-fidelity force sensing and real-time control. This paper proposes to employ a compliant constant-force mechanism in the end-effector of a polishing robot to passively maintain a constant force between the robot and the mirror, thus eliminating the requirement for force sensing and closed-loop control. The compliant constant force mechanism utilizing the second bending mode of fixed-guided compliant beams is adopted and elaborated for the passive end-effector. An end-effector providing a constant contact force of 40 N is designed and prototyped. The polishing experiment shows that the passive constant-force end-effector provides stable contact force between the robot and the mirror with fluctuation within 3.43 N, and achieves RMS (Root Mean Square) lower than λ/10 (λ = 632.8 nm) of the polished surface of the large-aperture optical reflective mirror. It is concluded that the constant-force compliant mechanism provides a low-cost and reliable solution for force control in robotic polishing.
Reservoir pore spaces (incl. pores, fractures and vugs) are too complex to be predicted by use of the traditional interrelationships between the four properties of reservoirs, thus more and more ...contradictions occur in reservoir evaluation. A great number of case studies were made to reveal the causes of these contradictions and the corresponding solutions were also proposed. For the reservoirs with complex pore spaces, we found four common types of contradictions between porosity and permeability, porosity and water saturation, absolute permeability and effective permeability, and electrical property and hydrocarbon property. These contradictions are mainly caused by variation of pore types, pore-throat sizes and fracture occurrence. On this basis, the concept of geometrical property was presented and methods were discussed for qualitatively or quantitatively describing the geometrical properties of pores, fractures and vugs. The following findings were achieved. (1) For pores, two relationships were established between pores & throat sizes and rock textures, physical property & fluid property, and between pore types and fluid property & logging responses. (2) For fractures, five relationships were established between occurrence and pore texture index (m), radial extension and deep/shallow borehole resistivity, openness and fracture permeability, occurrence and matrix water saturation, and between development index and lithology. (3) For vugs, two relationships were established between size & connectivity and m value & three porosities derived from logging responses (neutron, density and sonic wave), and filling degree and logging responses. The interrelationships between geometrical property, lithology, physical property, fluid property and electrical property can significantly improve the evaluation of complex reservoirs such as carbonates.
A wavefront correction method is proposed for high-precision optic surfacing, addressing the discrepancy between wavefront and real surface errors in Fizeau interferometer testing. We believe this to ...be a proposed novel method that encompasses optical surface function parameters fitting, lateral distortion correction, misalignment error removal, and sag surface error calculation. The method's error has been thoroughly analyzed, including aspects of function parameters fitting, ray tracing, and interpolation. The effectiveness of the method was demonstrated by correcting the wavefront of an off-axis parabolic mirror in null testing configurations, significantly reducing artificially created annular errors and improving off-axis direction errors from 0.23λ to 0.05λ (λ=632.8 nm), with the PV of aspheric departures exceeding 8.5 mm.
•The signal analysis step has been adopted in absolute surface error calibration for filtering out undesirable rotations angle.•The algorithm validation technology of the calibration was conducted ...using randomly generated surface profiles with power spectral density from experiment.•Quantitative analysis and calibration were performed to assess errors introduced by clamping stress, vibrations, airflow disturbances, angular errors and eccentricity.•The verification was conducted with standard mirror to prove the robustness, accuracy, and responsiveness.
A novel absolute surface calibration method for interferometer testing based on power spectral density analysis has been proposed. The method involves obtaining the loss of signal at different frequencies as a function of various rotation angles by signal analysis to choose the rotation angle for calibration. A model is developed to evaluate the calibration method by creating random surface shapes based on the Power Spectral Density. Using this algorithm, the precision of the absolute testing method during the testing process exceeds 0.28 %. Error propagation during the experimental process, such as testing optic clamping, angular errors, eccentricity, vibrations and airflow disturbances, were calibrated. Ultimately, the absolute detection test results were verified using high-precision flat mirrors. The experimental result indicates an RMS of 4.275 nm, 4.263 nm, and 4.265 nm in different rotation angle, and the calibrated result shows an RMS of 4.880 nm. The shape of surface errors in the absolute test results and calibration results is consistent.
Polishing plays an indispensable role in optical processing, especially for large-aperture optical reflective mirrors with freeform surfaces. Robotic polishing requires effective control of the ...contact force between the robot and the mirror during processing. In order to maintain a constant contact force during polishing, traditional polishing robots rely on closed-loop control of air cylinders, whose performances heavily rely on high-fidelity force sensing and real-time control. This paper proposes to employ a compliant constant-force mechanism in the end-effector of a polishing robot to passively maintain a constant force between the robot and the mirror, thus eliminating the requirement for force sensing and closed-loop control. The compliant constant force mechanism utilizing the second bending mode of fixed-guided compliant beams is adopted and elaborated for the passive end-effector. An end-effector provid- ing a constant contact force of 40 N is designed and prototyped. The polishing experiment shows that the passive constant-force end-effector provides stable contact force between the robot and the mirror with fluctuation within 3.43 N, and achieves RMS (Root Mean Square) lower than λ/10 (λ = 632.8 nm) of the polished surface of the large-aperture optical reflective mirror. It is concluded that the constant-force compliant mechanism provides a low-cost and reliable solution for force control in robotic polishing.
OBJECTIVE: To analyze the effect of needling acupoints(bilateral vs unilateral) with De Qi using data collected from 501 primary dysmenorrhea(PD) patients participating in multi-center, ...randomized,controlled trail.METHODS: De Qi was defined as at least one of the feelings in soreness, numbness, fullness or heaviness at the acupoints when stimulated with needles. The 501 patients were grouped in 3 groups in terms of De Qi or not De Qi in one side(unilateral)or both sides(bilateral) of the body: bilateral De Qi group, unilateral De Qi group, and non-De Qi group. The abdominal pains were measured using visual analog scale(VAS).RESULTS: In 501 patients, 472 acquired De Qi at unilateral acupoints, 24 De Qi at bilateral acupoint,and 5 had no De Qi at any acupoint. The data of non-De Qi group was excluded as the sample was less than 5% of that in the bilateral De Qi group.There was significant difference in the VAS before and after treatment between unilateral and bilateral De Qi group(P < 0.01). After stratified by acupoints, for the patients needled at Sanyinjiao(SP 6)and Xuanzhong(GB 39), VAS scores in the bilateral De Qi group were larger than those in the unilateral De Qi group(P < 0.05).CONCLUSION: Bilateral De Qi was possibly superior to unilateral De Qi in enhancing the immediate analgesic effect of needling the acupoints, but no statistical significance was observed on the pa-tients of needling at non acupoint, which preliminarily suggested this immediate analgesic effect was perhaps along meridians.
OBJECTIVE： To analyze the effect of needling acupoints（bilateral vs unilateral） with De Qi using data collected from 501 primary dysmenorrhea（PD） patients participating in multi-center, ...randomized,controlled trail.METHODS： De Qi was defined as at least one of the feelings in soreness, numbness, fullness or heaviness at the acupoints when stimulated with needles. The 501 patients were grouped in 3 groups in terms of De Qi or not De Qi in one side（unilateral）or both sides（bilateral） of the body： bilateral De Qi group, unilateral De Qi group, and non-De Qi group. The abdominal pains were measured using visual analog scale（VAS）.RESULTS： In 501 patients, 472 acquired De Qi at unilateral acupoints, 24 De Qi at bilateral acupoint,and 5 had no De Qi at any acupoint. The data of non-De Qi group was excluded as the sample was less than 5% of that in the bilateral De Qi group.There was significant difference in the VAS before and after treatment between unilateral and bilateral De Qi group（P 〈 0.01）. After stratified by acupoints, for the patients needled at Sanyinjiao（SP 6）and Xuanzhong（GB 39）, VAS scores in the bilateral De Qi group were larger than those in the unilateral De Qi group（P 〈 0.05）.CONCLUSION： Bilateral De Qi was possibly superior to unilateral De Qi in enhancing the immediate analgesic effect of needling the acupoints, but no statistical significance was observed on the pa-tients of needling at non acupoint, which preliminarily suggested this immediate analgesic effect was perhaps along meridians.
PDF
