Acoustics in small rooms suffer from resonances in low frequencies, resulting in the well-known sound colouration problem. In the present work, the finite element method was used to investigate specific case studies of proposed treatments of this problem. The treatments are based on techniques that make use of three basic mechanisms: wavelength, boundary impedance, and active control. The quality of the treatments is evaluated using two spatial statistical measures of the sound pressure level frequency responses regularly sampled in the listening area. The results demonstrate the advantage of the impedance-and active control mechanism-based techniques. Resonant panels and multiple source excitation treatments improve the sound field flatness.

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A technique for analysis of second order properties of planar two-degree-of-freedom mechanisms has been proposed. Analytical and graphical representations of the properties have been used to study the relative influence of input velocities and accelerations on the acceleration of the end point.

The ability to move at reasonable ease in all directions is an important requirement in the design of manipulators. The degree of ease of mobility varies from point to point in the workspace of the manipulator’s end effector. Maximum ease of mobility is obtained at an isotropic point, and the minimum occurs at singularities. An attempt has been made here to use a geometric approach for determining the isotropic points in the workspace of planar 5-bar linkages. The geometrical approach leads to interesting observations on the location of isotropic points in the workspace. The procedure also yields a technique for the synthesis of 5-bar linkages and associated coupler points exhibiting isotropic behaviour. Additionally it has been shown that coupler points exhibiting isotropic mobility occur in pairs.

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