Recent content by thadman

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    Natural frequencies of rectangular membranes

    Hello physicsforums members, I am an engineering student at Purdue University and am currently conducting research with regards to ribbon transducers. A ribbon transducer consists of a rectangular element of metal foil suspended within a magnetic gap (ie free at the sides) and...
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    Dynamic resistance vs temperature measurement for ribbon transducer

    A ribbon transducer is used as a microphone and/or loudspeaker. Here is a diagram of a ribbon microphone: http://www.shurenotes.com/issue37/images/images/article1_13.gif Assuming it is used as a loudspeaker, current is applied to the foil to create sound pressure. The loudspeaker is <10%...
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    Dynamic resistance vs temperature measurement for ribbon transducer

    I'm interested in doing an experimental analysis of ribbon transducers to contrast with simulations. This data could be made available to the community to aid in transducer development. A ribbon transducer consists of a rectangular element of metal foil suspended within a magnetic gap and...
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    Is Dispersion Present in Expanding Cylindrical Waves of an Infinite Radiator?

    Let us assume we possesses a line radiator. It's extent is infinite and it radiates 360*. As far as I understand, an expanding spherical wave of order 0 is not dispersive. I assume an expanding cylindrical wave of order 0 would possesses dispersion, however I am not certain. Could any...
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    Variable tension apparatus for transducer analysis

    The apparatus will be required to tension the membrane. After which, the membrane will be rigidly clamped to sustain a constant tension. Current will be applied to the membrane which will generate an electromagnetic field that will interact with the permanent magnetic field generated by 2...
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    Calculating Acoustic Radiation from Apertures driven by Ribbon Loudspeakers

    If the duct was engineered to provide a primarily resistive impedance above a particular frequency, where the uncoupled membranes fundamental resonance may lie, wouldn't the ducts effects (coupled membrane-duct) be reduced to a broadening of the Q of the fundamental, rather than a shift of the...
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    Variable tension apparatus for transducer analysis

    I'm interested in building a ribbon loudspeaker in my free time over Christmas break and would like to drive it directly. Following the resolution of some meetings with faculty in the engineering department, I might be able to gain access to the Universities Laser Vibrometer and Anechoic chamber...
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    Calculating Acoustic Radiation from Apertures driven by Ribbon Loudspeakers

    I'm interested in building a DIY ribbon loudspeaker in my free time over Christmas break and would like to drive it directly. Following the resolution of some meetings with faculty in the engineering department, I might be able to gain access to the Universities Laser Vibrometer and Anechoic...
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    Calculating Acoustic Radiation from Apertures driven by Ribbon Loudspeakers

    Would it be easier to solve for the fundamental resonance of a tensioned membrane within a particular duct geometry? The texts I have available (Mechanical Vibrations and Roark's Formulas for Stress and Strain) make reference to rectangular plates, but do not combine plate stiffness and...
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    Analytical Calculation/Optimization of Ironless Motor Structure

    I'm interested in calculating (followed by optimizing) the uniformity of a magnetic field generated by an array of neodymium magnets. Let us assume we have an array of neodymium bar magnets, -each with a constant depth (10mm) and height (2300mm). -Multiple segments (with alternating poles)...
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    Calculating Acoustic Radiation from Apertures driven by Ribbon Loudspeakers

    Perhaps a more specific description of my problem would be more appropriate. A loudspeaker distributes energy throughout the room. We must consider the direct response as well as the power response. The direct response can be visualized as a vector that extends from the acoustic center of the...
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    Calculating Acoustic Radiation from Apertures driven by Ribbon Loudspeakers

    I would be very appreciative to see the solution as well as the CFD plots.
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    Calculating Acoustic Radiation from Apertures driven by Ribbon Loudspeakers

    http://www.aes.org/tmpFiles/elib/20091022/12398.pdf A ribbon loudspeaker consists of a rectangular element of aluminum foil suspended within a magnetic gap and clamped at its ends (ie a clamped-clamped beam). Current is applied to the foil, which produces an electromagnetic field that...
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    Resonances of Cylindrical Shells with uniform radial pressure

    I have picked up "Roark's Formulas for Stress and Strain" and "Mechanical Vibrations" and have been unable to reach resolution on a particular problem. I am interested in the behavior of a uniform cylindrical shell (cylinder diameter >> wall thickness) rigidly clamped at both ends wherein...
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    Can we achieve linearity in helical springs like in cantilever design?

    With regards to my previous posts, For defining the natural frequencies of a beam rigidly coupled at both ends, we are given the equation: F(X)=(Kn/2pi)*sqrt(EI/Rho*A*(L^4)) where: Kn=mode number E=elastic modulus I=area moment of inertia (ie second moment of inertia, I believe)...
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