23 research outputs found

    Experimental researches of a flexible waveguide of ultrasound vibrations

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    In this paper we report the results of experimental research of a new flexible and variable-rigidity waveguide, which operation is based on ultrasound vibrations. The tested waveguide is a combination of conical-stepped-cylindrical waveguides, which enables significant improvement of dynamic characteristics with respect to various existing static loads. The resonant frequency for excitation of the waveguide is in the range of 24-26 kHz. The measurements presented in this paper were performed on a STANDA vibration-isolation honeycomb-type table by means of the POLYTEC laser Doppler vibrometer system MSV-400 consisting of a laser interferometer OFV-512, vibrometer controller OFV-5000 and analog-to-digital converter ADC-2424 (PICO,GB) as well as by using HYTEC holographic interferometry system PRIS

    Experimental investigation of vibrational drilling.

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    International audienceDuring experimental study of vibrational drilling resonant frequencies of the developed tool were evaluated as well as drilling experiments were performed including measurements of cutting force, torque and surface quality, which indicate improvement with respect to conventional drilling and confirm that vibrational drilling can be successfully applied for process efficiency enhancement

    Numerical-experimental identification of the most effective dynamic operation mode of a vibration drilling tool for improved cutting performance.

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    International audienceThis study is concerned with application of numerical-experimental approach for characterizing dynamic behavior of the developed piezoelectrically excited vibration drilling tool with the aim to identify the most effective conditions of tool vibration mode control for improved cutting efficiency. 3D finite element model of the tool was created on the basis of an elastically fixed pre-twisted cantilever (standard twist drill). The model was experimentally verified and used together with tool vibration measurements in order to reveal rich dynamic behavior of the pre-twisted structure, representing a case of parametric vibrations with axial, torsional and transverse natural vibrations accompanied by the additional dynamic effects arising due to the coupling of axial and torsional deflections ((un)twisting). Numerical results combined with extensive data from interferometric, accelerometric, dynamometric and surface roughness measurements allowed to determine critical excitation frequencies and the corresponding vibration modes, which have the largest influence on the performance metrics of the vibration drilling process. The most favorable tool excitation conditions were established: inducing the axial mode of the vibration tool itself through tailoring of driving frequency enables to minimize magnitudes of surface roughness, cutting force and torque. Research results confirm the importance of the tool mode control in enhancing the effectiveness of vibration cutting tools from the viewpoint of structural dynamics

    Comparison of the 2008 Farm Bill Conference Agreement with the House and Senate Farm Bills

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    In late May, both the House and the Senate voted to override a presidential veto of the conference agreement on the 2008 farm bill (H.R. 2419, the Food, Conservation, and Energy Act of 2008), and the conference bill became law on May 22, 2008 (P.L. 110-234). However, an enrolling error resulted in one title of the bill (Title III, Trade) being omitted from the version that was sent to the White House, and the newly enacted law contains 14 of 15 farm bill titles. To resolve this issue, both the House and Senate passed a version of the 2008 farm bill with all 15 original bill titles (H.R. 6124). The President vetoed this bill version on June 18. That same day both the House (80-14) and the Senate (317-109) voted to override the veto and the bill became law (P.L. 110-246), replacing P.L. 110-234. The conference agreement contains 15 titles covering support for commodity crops, horticulture and livestock production, conservation, nutrition, trade and food aid, agricultural research, farm credit, rural development, energy, forestry, and other related programs. It also includes tax-related provisions that would make certain changes to tax laws, in order to offset new spending initiatives in the respective bills. The bill is intended to replace the most recent 2002 farm bill (P.L. 107-171) and to guide most federal farm and food policies through FY2012. Many provisions of the 2002 farm bill expired in September 2007, but were extended under a series of temporary extensions enacted during the farm bill debate. This report compares the major provisions in the House- and Senate-passed bills and the conference agreement with each other and with the 2002 law, and provides a brief description of all individual sections or subsections within each title
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