Air force Institute of Technology Taiwan

Kaohsiung, Taiwan

Air force Institute of Technology Taiwan

Kaohsiung, Taiwan

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Lin C.-C.,Air force Institute of Technology Taiwan | Yu E.-Z.,National Kaohsiung Normal University | Huang C.-Y.,National Kaohsiung Normal University
IEEE Antennas and Wireless Propagation Letters | Year: 2012

Design of a coplanar waveguide (CPW)-fed rhombus slot antenna for dual-band operation is proposed. With appropriate rhombic ring feeding structure and rectangular bulge components for impedance matching, the proposed antenna can provide two separate impedance bandwidths of 607 MHz (about 24.7% centered at 2.45 GHz) and 1451 MHz (about 26.3% centered at 5.5 GHz), which satisfies the WLAN operation in the 2.45-GHz band (about 3.4% bandwidth required) and 5.2/5.8-GHz bands (about 13% bandwidth required). Details of the constructed prototypes and experimental results are discussed. © 2012 IEEE.

Huang Y.-S.,National Ilan University | Pan Y.-L.,Air force Institute of Technology Taiwan | Zhou M.,Tongji University | Zhou M.,New Jersey Institute of Technology
IEEE Transactions on Systems, Man, and Cybernetics Part A:Systems and Humans | Year: 2012

Deadlock prevention, deadlock detection, and deadlock avoidance strategies are used to solve the deadlock problems of flexible manufacturing systems. The theory of regions is recognized as the unique method for obtaining maximally permissive (i.e., optimal) controllers in the existing literature. All legal and live maximal behavior of a Petri net model can be preserved by using a marking/transition-separation instance (MTSI). However, obtaining them is an extremely time consuming problem. This work proposes crucial MTSIs that allow designers to employ much fewer MTSIs to deal with deadlocks. The advantage of the proposed policy is that an optimal deadlock controller can be obtained with drastically reduced computation. Experimental results, by varying the markings of given net structures, indicate that it is the most efficient policy to obtain such controllers. © 2011 IEEE.

Chung J.C.,Air force Institute of Technology Taiwan
Tribology International | Year: 2010

The work presents a finite element model (FEM) of the equivalent von-Mises stress and displacements that are formed for the different ellipticity contact of an ellipsoid with a rigid flat. The material is modeled as elastic perfectly plastic and follows the von-Mises yield criterion. The smaller the ellipticity of the ellipsoid is, the larger the depth of the first yield point from the ellipsoid tip happens. The FEM produces contours for the normalized normal and radial displacement as functions of the different interference depths. The evolution of plastic region in the asperity tip for a sphere (ke=1) and an ellipsoid with different ellipticities (ke = frac(1, 2) and frac(1, 5)) is shown with increasing interferences. It is interesting to note the behavior of the evolution of the plastic region in the ellipsoid tip for different ellipticities, ke, is different. The developments of the plastic region on the contact surface are shown in more details in Fig. 7. When the dimensionless contact pressure is up to 2.5, the uniform contact pressure distribution is almost prevailing in the entire contact area. It can be observed clearly that the normalized contact pressure ascends slowly from the center to the edge of the contact area for a sphere (ke=1), almost has uniform distribution prevailing the entire contact area for an ellipsoid (ke = frac(1, 2)), and descends slowly from the center to the edge of the contact area for an ellipsoid (ke = frac(1, 5)). © 2009 Elsevier Ltd. All rights reserved.

Tu T.W.,Air force Institute of Technology Taiwan
Acta Mechanica | Year: 2016

This paper proposes that Kane’s equations for a simple nonholonomic system are the first-order form of generalized speeds. When the first-order form of Kane’s equations is put in matrix form, the element of the mass matrix is identical to the inertia coefficient. Because the orthogonal set of partial velocities will decouple the first-order equations, one can use the orthogonal criterion to generate efficient equations of motion. With the presented first-order form, Kane’s equations are different from Maggi’s or Gibbs–Appell’s equations. Moreover, in order to clarify the relationship between Kane’s approach and classical approaches, we start from Kane’s equations and introduce kinetic energy or acceleration energy functions to derive Lagrange’s or Gibbs–Appell’s forms of Kane’s equations for the system. We found that the Lagrange’s forms of Kane’s equations can be used to solve nonholonomic systems without introducing Lagrangian multipliers. At last, the first-order form, Lagrange’s forms, and Gibbs–Appell’s forms of Kane’s equations are, respectively, used to depict the derivation of first-order equations of motion for a rolling coin. © 2016 Springer-Verlag Wien

Chen K.Y.,Air force Institute of Technology Taiwan
IEEE/ASME Transactions on Mechatronics | Year: 2016

In this paper, the proposed sliding mode minimum-energy control (SMMEC) consists of sliding mode control (SMC) and minimum-energy control (MEC), and is proposed for a mechatronic motor-table system. First, the complete mathematical model containing the mechanical and electrical equations is successfully formulated, and the energy balance equation is found. Second, the MEC based on Hamiltonian function is exactly obtained from the linear motor-table system. The SMC is added to have the good robustness control performance for the nonlinear motor-table system with external loading, forces and frictions. Our main contribution in this paper is to integrate the MEC's minimum energy and SMC's robustness control performances, and the SMMEC is proposed to perform the robust MEC for the nonlinear mechatronic motor-table system. Finally, the proposed SMMEC is realized by experiments to validate its performance of robustness and saving energy, and comparisons between numerical simulations and experimental results are made for the nonlinear mechatronic motor-table system. © 1996-2012 IEEE.

Lin C.-C.,Air force Institute of Technology Taiwan
IEEE Antennas and Wireless Propagation Letters | Year: 2012

In this letter, a bow-tie quasi-self-complementary antenna (QSCA) for ultrawideband (UWB) applications is presented and discussed. By a coplanar waveguide (CPW)-like matching technique, the proposed antenna provides a broad VSWR< 2:1 impedance bandwidth from 3.04 to 11.47 GHz. This feature is in favor of covering the required bandwidth from 3.1- to 10.6-GHz UWB operations. Additionally, the compact size (10 × 35 mm 2) of the antenna is favorable for integration with wireless communication devices on restricted radio-frequency elements space. © 2002-2011 IEEE.

This study demonstrates the coupling between the backward cladding mode and the backward core mode in a fiber Bragg grating (FBG) cascaded with a long period grating (LPG) to create induced wavelength channels for detecting refractive index variation. Cladding-to-core mode coupling is based on the phase matching condition in which the wave vector of the LPG is equal to the difference between the backward core mode and the backward cladding mode wave-vector in FBG. Moreover, by means of varying the refractive index of the surrounding cladding layer region from an FBG end to the other LPG end, the reflectivity of both the induced wavelength channels and the Bragg wavelength channel is therefore changed due to different mode couplings. This property of index sensing of concatenating an FBG and an LPG by monitoring the reflection power may be exploited for chemical sensing and environmental monitoring applications. © 2012 IEEE.

Jang J.-Y.,National Cheng Kung University | Hsu L.-F.,National Cheng Kung University | Leu J.-S.,Air force Institute of Technology Taiwan
International Journal of Heat and Mass Transfer | Year: 2013

A numerical analysis was carried out to study the thermal-hydraulic characteristics of a 3-D laminar in-lined and staggered plate-fin and tube heat exchangers with block type vortex generators (VG) mounted behind the tubes. In this study, the optimization of the VG span angle (θ) and the VG transverse location (Ly) was investigated numerically along with a simplified conjugate-gradient method (SCGM). The area reduction ratio using a vortex generator relative to the plain surface is the objective function to be maximized. A search for the optimum span angle (θ) and transverse location (Ly), ranging from 30 < θ < 60 and 2 mm < L y < 20 mm, respectively, was performed. The effect of different inlet conditions, (Reynolds number ReDh = 400-1200), was also investigated. The results showed that the maximum area reduction ratios reached 14.9-25.5% combined with the optimal design of (θ, Ly) at ReDh = 400-1200 for the in-lined arrangement, and 7.9-13.6% of the maximum area reduction ratio was achieved for the staggered arrangement. © 2013 Elsevier Ltd. All rights reserved.

Liao M.-L.,Air force Institute of Technology Taiwan
Journal of Nanoparticle Research | Year: 2012

Hydrogen adsorption behaviors of singlewalled open-tip (tip-truncated) carbon nanocones (CNCs) with apex angles of 19.2 at temperatures of 77 and 300 K were investigated by the molecular dynamics simulations. Four nanomaterials (including three CNCs with different dimensions and a reference CNT) were analyzed to examine the hydrogen adsorption behaviors and influences of cone sharpness on the behaviors of the CNCs. Physisorption of hydrogen molecules could be observed from the distribution pattern of the hydrogen molecules adsorbed on the nanomaterials. Because of the cone geometry effect, the open-tip CNCs could have larger storage weight percentage and less desorption of hydrogen molecules (caused by the temperature growth) on their outer surfaces, as compared with those of the reference CNT. The hydrogen molecules inside the CNCs and the reference CNT, however, were noted to have similar desorption behaviors owing to the confinement effects from the structures of the nanomaterials. In addition, the sharper CNC could have higher storage weight percentage but the cone sharpness does not have evident enhancement in the average adsorption energy of the CNC. Combination of confinement and repulsion effects existing near the tip region of the CNC would be responsible for the non-enhancement feature. © 2012 Springer Science+Business Media B.V.

Liao M.-L.,Air force Institute of Technology Taiwan
Applied Physics A: Materials Science and Processing | Year: 2014

This paper used molecular dynamics simulations to investigate buckling behaviors of open-tip carbon nanocones (CNCs) at elevated temperatures ranging from 300 to 700 K. Influences of cone height and apex angle on the buckling behaviors were examined. Some interesting findings, especially on the change in buckling mode shapes of the CNCs, were observed in the study. For the CNCs having an apex angle of 19.2°, the one with a lower cone height exhibited a shrinking/swelling buckling mode shape even at the higher temperature 700 K. However, as the cone height increased, the CNC displayed a deflective buckling mode shape at 300 K, but changed to a shrinking/swelling buckling mode shape when the temperature grew to 500 K. Regarding the influences of apex angle, the CNCs presented a deflective buckling mode shape even at 700 K as the apex angle expanded. This is opposite to the shrinking/swelling buckling mode shape of the CNC having the smallest apex angle of 19.2°. © 2014, Springer-Verlag Berlin Heidelberg.

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