Real-time monitoring and control system of an industrial robot with 6 degrees of freedom for grinding and polishing of aspherical mirror
Aspherical mirrors have higher performance and lighter weight than spherical mirrors. However, it is not easy to process, measure, and evaluate their shapes. In particular, large aperture aspherical mirrors used in satellites require high precision and take a long time to process. The conventional process is machined using a computer numerical control with a gantry structure. However, there is a disadvantage that it is difficult to process complex shapes due to lack of degrees of freedom. In order to overcome these problems, we developed a shape processing system using an industrial robot with 6 degrees of freedom. The system consists of toolpath generation program, real-time robot monitoring, and control program. We have verified the performance of the developed system through simulation software provided by the robot manufacturer as well as actual robot operation.
Ultra-precision Grinding Optimization of Mold Core for Aspheric Glass Lenses using DOE and Compensation Machining
The aspheric lens has become the most popular optical component used in various optical devices such as digital cameras, pick-up lenses, printers, copiers etc. Using aspheric lenses not only miniaturizes and reduces the weight of products, but also lower prices and higher field angles can be realized. Additionally, plastic lenses are being changed to glass lenses more recently because of low accuracy, low acid-resistance and low thermal-resistance in the plastic lenses. Currently, one fabrication method of glass lenses is using a glass-mold method with a high precision mold core for mass production. In this paper, DOE (Design Of Experiments) and compensation machining were adopted to improve the surface roughness and the form accuracy of the mold core. The DOE has been done in order to discover the optimal grinding conditions which minimize the surface roughness with factors such as work spindle revolution, turbine spindle revolution, federate and cutting depth. And the compensation machining is used to generate high form accuracy of the mold core. From various experiments and analyses, we could obtain the best surface roughness 5 nm in Ra, form accuracy in PV.
The uprising of the marginalised: a socio-economic perspective of the Syrian uprising
More than three years after the outbreak of protests in a number of Arab countries, the role of socio-economic factors in these events is attracting more attention. One of the cases that needs more research is Syria. More than three years into the Syrian uprising, the socio-economic roots of the protest movement that became one of the bloodiest civil conflicts in the history of the Middle East need to be examined. While it has been observed that the Syrian uprising, contrary to some ‘Arab Spring’ countries, has been an uprising of more marginalised social groups with a strong role played by poorer segments in the society, particularly rural and rural-to-urban migrants, the socio-economic explanation for this is still underdeveloped. This paper aims at contributing to a better understanding of this issue by examining the political and socio-economic compromise that underlined the rule of the Ba’th party in Syria for four decades and unpacking how a combination of internal and external shifts that started in the 1990s and intensified in the 2000s led to the erosion of this compromise, providing the background to the events that began in 2011.