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| 1 | A new solution to enhance cuttings transport in mining drilling by using pulse jet mill technique显示文摘In horizontal drilling, the cuttings bed is frequently formed to result in severe problems such as backing pressure, binding of bottom hole assembly(BHA) and even sticking of tool. Practice and research show that the smaller particle size is, the more favorable to carry out from bottom of hole in extended reach well or horizontal well. This paper presented a new solution to enhance cuttings transport in mining drilling through a new type of bit called pulsed mill bit(PMB) by using pulse jet mill technique. It provides a promising solution to enhance the efficiencies of rock breaking and cuttings carrying for pulsed jet,sucking cuttings to decrease the chip hold down effect, and reducing cuttings' diameter to eliminate cuttings bed. The design was supported by the calculation models of Helmholtz resonator natural frequency, optimal drilling fluid flow rate of resonator,drilling fluid flow velocity in forward jet channel, critical impact velocity of cuttings and minimum length of the accelerating cavity. Meanwhile, factors affecting optimal drilling fluid flow rate, critical impact velocity of cuttings and minimum length of accelerating cavity were investigated. Case study showed a good consistency between the calculation results and the related theories. It is concluded that optimal drilling fluid flow rate increases with the increase of inlet and outlet cavity's diameter, and decreases with the increase of the diameter of the resonant cavity. Critical impact velocity of cuttings increases with the energy conversion factor(β) and ROP, while decreasing with the final size of the cuttings(d_t). This effect is obvious when β<0.2, ROP<3.048 mh^(-1) and d_t<0.3 mm. Minimum length of the accelerating cavity decreases with the increase of the resonator's natural frequency and separation coefficient(α) of drilling fluid flow rate. This study provides a promising solution to remove cuttings bed in horizontal well. | LIU YongSheng GAO DeLi WEI Zheng BALACHANDRAN Balakumar WANG ZhenQuan TAN LeiChuan | 2019 | Science China(Technological Sciences)2019，62，5： | 1 |
| 2 | Corrigendum to“Noise colour influence on escape times in nonlinear oscillators-experimental and numerical results”[Theor.App.Mech.Lett.13(2023)100420]显示文摘The original article includes the incorrectly printed Figs.1,2 and 4.The correct figures are included in this note.Fig.1.(a)Experimental setup:The shaker is used to generate the external,harmonic and random excitation to the base of the metal cantilever.The resulting oscillations are measured with a strain gauge.A nonlinear restoring force follows from the magnets mounted at the cantilever tip and the fixed frame.(b)Measured cantilever response to sinusoidal excitation and experimental procedure:A sweep up is used to realize the high amplitude orbit.When the excitation frequency reaches 39.6 Hz,noise is added to the input and a noise induced escape is observed.(c)Time series of a strain gauge signal:The forcing frequency is 39.6 Hz and the response is initiated in the high energy orbit.After about 37.0 s an escape towards the low amplitude orbit is observed. | Thomas Breunung Balakumar Balachandran | 2023 | Theoretical & Applied Mechanics Letters2023，13，3： | 0 |
| 3 | Motion visualization and estimation for flapping wing systems显示文摘Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. As a case study, motion capture of a free flying Manduca sexta, also known as hawkmoth, is considered by using three synchronized high-speed cameras. A solid finite element(FE) representation is used as a reference body and successive snapshots in time of the displacement fields are reconstructed via an optimization procedure. One of the original aspects of this work is the formulation of an objective function and the use of shadow matching and strain-energy regularization. With this objective function, the authors penalize the projection differences between silhouettes of the captured images and the FE representation of the deformed body. The process and procedures undertaken to go from high-speed videography to motion estimation are discussed, and snapshots of representative results are presented.Finally, the captured free-flight motion is also characterized and quantified. | Tzu-Sheng Shane Hsu Timothy Fitzgerald Vincent Phuc Nguyen Trisha Patel Balakumar Balachandran | 2017 | Acta Mechanica Sinica2017，33，2： | 0 |
| 4 | Noise color influence on escape times in nonlinear oscillators-experimental and numerical results显示文摘The interplay between noise and nonlinearites can lead to escape dynamics.Associated nonlinear phe-nomena have been observed in various applications ranging from climatology to biology and engineering.For reasons of computational ease,in most studies,Gaussian white noise is used.However,this noise model is not physical due to the associated infinite energy content.Here,the authors present extensive experimental investigations and numerical simulations conducted to examine the impact of noise color on escape times in nonlinear oscillators.With a careful parameterization of the numerical simulations,the authors are able to make quantitative comparisons with experimental results.Through the experi-ments and simulations,it is illustrated that the noise color can drastically influence escape times and escape probability. | Thomas Breunung Balakumar Balachandran | 2023 | Theoretical & Applied Mechanics Letters2023，13，2： | 0 |
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