Abstract: The governing equations of motion for a drill string considering coupling between axial, lateral and torsional vibrations are obtained using a Lagrangian approach. The result leads to a set of non-linear equations with time varying coefficients. A fully coupled model for axial, lateral, and torsional vibrations of drill strings is presented. The bit/formation interactions are assumed ...

in this paper, based on equations of lateral vibrations of wires, a non contact method for measuring instantaneous tension in a wire is introduced. the lateral vibration of the string is measured using an eddy current transducer and is sent to a computer. this signal is then imported to suitable software for fast fourier transform (fft) processing. the first natural frequency of the string is c...

This is the first of a series three papers on open string field theories based Witten star product deformed with gauge invariant open/closed coupling. deformation tree-level tadpole which destabilizes initial perturbative vacuum. We discuss existence vacuum-shift solutions cancel and represent new configuration where D-brane system has adapted to change in closed background. As an example we co...

According to the temperature distribution of water injection well-bore in highly deviated wells under different conditions and unstable temperature field heat conduction principles, a true three-dimensional model was established to analyze the law of variation on temperature of highly deviated wells during the water injection process, and to analyze the factors that influence the water injectio...

This paper presents a model-based approach for the global maximum power point (GMPP) tracking of solar strings under partial shading conditions. In the proposed method, the GMPP voltage is estimated without any need to solve numerically the implicit and nonlinear equations of the photovoltaic (PV) string model. In contrast to the existing methods in which first the locations of all the local pe...

background: appendectomy is the most common emergency operation performed in the world. this study aimed to compare complication of simple legation of the appendix with purse string diving appendectomy. methods: randomized clinical trial designed 361 patients who had underwent appendectomy during 2008 and 2009 in imam reza and taleghani hospitals, kermanshah, iran, were included. those patients...

aim : evaluation of biological characteristics of 13 identified proteins of patients with cirrhotic liver disease is the main aim of this research.   background : in clinical usage, liver biopsy remains the gold standard for diagnosis of hepatic fibrosis. evaluation and confirmation of liver fibrosis stages and severity of chronic diseases require a precise and noninvasive biomarkers. since the...