Laser drilling is a well-established process in aerospace industry. However quality and geometry of holes do not get under control in an absolute way. Moreover, drilling understanding is complicated due to the number of parameters and physical phenomena. Laser and matter have some own parameters which are not constant with temperature, and so could not be fitted. In this paper, we describe the ...

Here we present a method for high-precision drilling using an industrial robot with high-bandwidth force feedback, which is used for building up pressure to clamp-up an end-effector to the work-piece surface prior to drilling. The focus is to eliminate the sliding movement (skating) of the end-effector during the clamp-up of the end-effector to the work-piece surface, an undesired effect that i...

BTA 1 deep hole drilling is a method for producing precision bores with high length to diameter ratios. The long and slender tools feature low torsional and bending stiffness. This may lead to undesirable dynamic disturbances of the machining process usually classified as either chatter vibration or spiralling. Prediction and identification of the causes of these process failures is important f...

The fracture and crack growth of mechanical structures is a usual phenomenon which is due to the application of tensile, cyclic loading or thermal stresses on the structure. So introducing of methods to prevent the crack growth is useful. Afterward, one of the repairing methods of crack growth, consisting to make a hole in the crack tip to elimi-nate the sharp corners, was explained. This metho...

Received 3/30/2009; revised 4/13/2009; accepted 4/21/2009. For correspondence and reprints contact: Chi-Yun Chen, M.D., Department of Nuclear Medicine, Antai Tian-Sheng Memorial Hospital. 210 Section 1, ChungCheng Road, Tungkang, Pingtung 92842, Taiwan. Tel: (886)8-8329966 ext. 1631, Fax: (886)8-8329977, E-mail: [email protected] Objective: The purpose of this study was to compare the image...

a new method for determination of residual stresses in the bottom layers of laminated composites is developed. in this method the residual stresses are determined by performing a consecutive drilling of laminated composites in the center of the rosette and recording the strains after drilling each layer. the depth of the hole in each step is equal to the thickness of each layer and the maximum ...

The stability of the Schwarzschild black hole is studied. Regge and Wheeler treated the problem first at 1957 and obtained the dynamical equations for the small perturbation. There are two kinds of perturbations: odd one and even one. Using the Painlevé coordinate, we reconsider the odd perturbation and find that: the white-hole-connected universe (r > 2m, see text) is unstable. Because the odd...

BACKGROUND The Medicare Prescription Drug, Improvement, and Modernization Act, signed into law in 2003, provided access to prescription drugs for elderly Americans. The Part D benefit continues to evolve. Changes in plan designs, the impact of the doughnut hole on beneficiaries, and increased cost shifting have the potential to hamper the future of the Part D benefit. OBJECTIVE To discuss fac...

Inadequate hole cleaning can lead to many problems in horizontal and directional wells. In this work, we tried to investigate the cutting transport phenomenon by an experimental directional drilling simulator, considering the differences between the operational and experimental conditions. The inclination, fluid type (water, foam, viscous, and dense), rotary speed (0 and 110 rpm), nozzle bit si...