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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. Source

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. Source

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 Source

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. Source

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. Source

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