Applied Mechanics and Materials Vols. 284-287

Abstract: With the increase of areal density in hard disk drive (HDD), the mechanical spacing between magnetic head and disk has decreased to sub~1nm. Under such ultra-low spacing, accurate spacing control becomes more important for lowering down the risk of head-disk interference and getting good bit per inch (BPI) performance. Dual-heater slider technology has been considered as a most useful solution. This paper introduces the advantages of dual heater in reading/writing spacing control. Furthermore, as a key issue in precise spacing control, the touchdown detectability of dual-heater slider was also investigated using three TD detection methods under writing and reading mode. Result shows that a single method is difficult to get the best TD detectability under both writing and reading mode. Instead, hybrid method may be a feasible solution.

Abstract: Frequency dependence on image reconstruction for a buried conducting cylinder is investigated. A conducting cylinder of unknown shape scatters the incident wave in free space and measured the scattered field. By using measured fields, the imaging problem is reformulated into an optimization problem and solved by the steady-state genetic algorithm (SSGA). Numerical results show that the reconstruction is quite well in the resonant frequency range. This work provides both comparative and quantitative information

Abstract: Classical physics can be regarded as a special case of modern physics. Therefore, we applied those aspects of established modern physics that are suitable for engineering considerations, used the quantum mechanics viewpoint to deal with the physics relations in thermodynamics, and discussed the relations among the variables of physics. We obtained some results by deriving them from basic theories and physics relations, and by exploring the significance of mathematical physics. First, this study obtained the partial differential equation for the general physics relations, which is interesting and revolutionary thinking from the viewpoints of multi-physics and thermodynamic relations expansion. Meanwhile, variable relations among different physics disciplines can be obtained by applying the universal general physics relations with the Jacobian operator. The Maxwell relation is an even more special case; therefore, the physics relations obtained by this study are more universal and versatile. To further illustrate the advantages of this research, the partial differential equation obtained by this study is used to handle the various physics variables and to obtain the thermodynamic physics relations table. This study promotes the research and development of thermodynamic physics relations. There is still room for further exploration in future studies, especially in the specific area of multi-physics application relations and microscopic applications.

Abstract: The paper deals with numerical simulations of the impact of design, shading, positioning and orientation of a solar air collector an efficiency of exploitation of solar energy. The solar collector is used to preheat of an air, which then is supplied into the building. There are various requirements for solar air collectors. We are focused on maximization of solar energy gain by optimizing geometry, orientation and positioning of a solar air collector. To achieve the desired objective was a combination of two methods used. The firs one is Computational Fluid Dynamics (CFD) simulations of flow and heat transfer by convection, conduction and radiation in software ANSYS Fluent. The second one is the numerical simulation of the annual operations of the collector in the software BSim. The result of this work is an optimal design and operation conditions of the air collector.

Abstract: Radius of curvature is one of the key parameters of optical components. A variety of methods have been developed for this measurement. This paper describes a novel way, named “CMM spherometry by probe compensation”, to measure the radius of curvature of optical surfaces by coordinate measuring machine (CMM). The measurement combines CMM measurement and iteration calculation scheme is presented. The measurement results of CMM and the trace samples are compared. The effect of temperature compensation is discussed.

Abstract: Five-axis machine tools with three linear axes and two rotary axes can produce complex products with free-form surfaces requiring a high degree of precision. However, motion errors of each axis and its assembly error are accumulated in the positioning error of the cutting tool relative to a workpiece. There are many devices reported in the literature on the identification of kinematic errors based on the measurement of the motion error. According to the measurement paths in the ISO draft, ISO/CD 10791-6, the kinematic tests can be applicable to different configurations of five-axis machine tools. However, the advanced controller with tool center point (TCP) function is required while performing kinematic tests. This paper proposed the methodology of generating measurement path without TCP function for B-type five-axis machine tool. The developed module can transform the measuring path into an NC program used for lower hand controller. Verification using VERICUT solid cutting simulation software demonstrated the veracity of the generated five-axis NC code. The proposed methodology is applicable in a wide range of five-axis machine tool configurations; however, further testing with actual measuring applications will be required for further verification.

Abstract: Nowadays, cultural heritage has been preserved digitally more than physically. However, most of the research works have been focusing more on preservation of video elements even though preservation of audio is equally important. In this paper, the possibilities of generating different sounds in an acoustical heritage through the modulations of sound characteristics are explored on mobile devices. The modulations of the amplitude are based on tiles. In the proposed method, the user uses the one-tap gesture to initiate the start of sound changes on the physical interface of an immersive panoramic view on mobile platform by altering the amplitude of recorded audio piece and consequently producing different audible results. User interactions happen along the x and y-axes following the standard iOS system coordinate. This paper also demonstrates the programming method based on tiles and direct modulations of acoustical heritage in panoramic view with the interaction of the users in order to provide enhanced sensorial audio experience and acoustical engagement in action space on mobile platform. The result of the evaluation has shown that the volume playback has different amplitudes from the different coordinates that the users have tapped on.

Abstract: The direct mode shape expansion method is an iterative technique, then one can conclude that the convergence performance maybe challenged when applied to three-dimensional structures. In addition, mode shape values at different DOFs (degrees-of-freedom) sometimes are not in a same order of magnitude, which will produce much error for the estimation of small values of unmeasured mode components. Thus, this paper proposed a non-iterative mode shape expansion method based on coordinate decomposition and neglecting modelling errors between the finite element model and the experimental structure. The advantage of coordinate decomposition is that the unmeasured components of mode shape values could be estimated with different weighting coefficients, even in a physical meaningful interval. Numerical studies in this paper are conducted for a 30-DOF (degree-of-freedom) cantilever beam with multiple damaged elements, as the measured modes are synthesized from finite element models. The results show that the approach can estimate unmeasured mode shape values at translational and rotational DOFs in x, y and z directions with different weighting coefficients, respectively; and better mode shape expansion results can be obtained when proper constraints are employed.

Abstract: This paper presents a numerical comparison between the differential transform method and the modified Adomian decomposition method for solving the boundary layer problems arising in hydrodynamics. The results show that the differential transform method and modified Adomian decomposition method are easier and more reliable to use in solving this type of problem and provides accurate data as compared with those obtained by other numerical methods.

Abstract: This study develops an analytical model applicable for predicting the fluidic motion of an oscillating heat pipe (OHP) with asymmetric arrayed channel configuration. The analytic model considers the temperature difference between the average evaporating region and the average condensing region as the thermally driven force for the fluidic motion. The calculated results show that the closed-loop OHP with asymmetric arrayed channel under lower number of turns, lower filled liquid ratio, higher operating temperature and higher temperature difference between the average evaporating region and the average condensing region for the frequency ratio of unity could attain a better performance of the fluidic motions.