Browsing by Author "Tsai, Tsung-Han"

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Deassociate the initial temporal phase deviation provided by photoelastic modulator for stroboscopic illumination polarization modulated ellipsometry
(2011-03-01)
Tsai, Hsiu-Ming
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Chen, Chih-Wei
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Tsai, Tsung-Han
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Chao, Yu-Faye
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光電工程學系
In addition to operating the imaging ellipsometric measurements by four-specific temporal phases in the photoelastic modulated ellipsometry, we added the fifth one to solve the initial phase of the photoelastic modulator. This methodology has been developed to conquer the slow imaging processing of charge-coupled device camera for the stroboscopic illumination in the polarization modulated imaging ellipsometry. Without any calibration in its initial phase, we can perform the ellipsometric measurement by the measurements of intensity at five-specific temporal phases. The intensities of a full cycle for a point on SiO(2)/Si thin film were measured and analyzed for verifying this algorithm. The five stroboscopic illuminations were performed to measure the two-dimensional distribution of the same SiO(2)/Si thin film. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3568745]
Flowtable-Free Routing for Data Center Networks: A Software-Defined Approach
(2017-01-01)
Ren, Yi
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Tsai, Tsung-Han
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Huang, Ji-Cheng
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Wu, Cheng-Wei
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Tseng, Yu-Chee
The paradigm shift toward SDN has exhibited the following trends: (1) relying on a centralized and more powerful controller to make intelligent decisions, and (2) allowing a set of relatively dumb switches to route packets. Therefore, efficiently looking up the flowtables in forwarding switches to guarantee low latency becomes a critical issue. In this paper, following the similar paradigm, we propose a new routing scheme called KeySet which is flowtable-free and enables constant-time switching at the forwarding switches. Instead of looking up long flowtables, KeySet relies on a residual system to quickly calculate routing paths. A switch only needs to do simple modular arithmetics to obtain a packet's forwarding output port. Moreover, KeySet has a nice fault-tolerant capability because in many cases the controller does not need to update flowtables at switches when a failure occurs. We validate KeySet through extensive simulations by using general as well as Facebook fat-tree topologies. The results show that the KeySet outperforms the KeyFlow scheme [1] by at least 25% in terms of the length of the forwarding label. Moreover, we show that KeySet is very efficient when applied to fat-trees.
Hamiltonian decomposition of generalized recursive circulant graphs
(2016-09)
Chen, Y-Chuang
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Tsai, Tsung-Han
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資訊工程學系
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Department of Computer Science
In 2012, Tang et al. [9] proposed a new class of graphs called generalized recursive circulant (GRC) graphs, which is an extension of recursive circulant graphs. GRC graphs have a more flexible structure than recursive circulant graphs, while retaining their attractive properties, such as degree, connectivity, diameter, and routing algorithm. In this paper, the Hamiltonian decomposition of some GRC graphs is discussed. (C) 2016 Elsevier B.V. All rights reserved.
MicroApp: Architecting Web Application for Non-Uniform Trustworthiness in Cloud Computing Environment
(2014-01-01)
Hsu, Yen-Chun
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Wu, Yu-Sung
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Tsai, Tsung-Han
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Chiu, Yi-Pin
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Lin, Chih-Hung
An increasing number of web applications are now hosted in cloud infrastructures such as Amazon Web Services. Cloud infrastructures generally lack a uniform guarantee on security, reliability, performance, and cost. A privately owned cloud infrastructure may be considered more secure but less performant than a third-party public cloud infrastructure. Infrastructures that span across geographical regions may further incur complications on the trustworthiness of infrastructures due to the varying power of jurisdiction. Application developers have to be aware of the non-uniformity of infrastructure trustworthiness when deploying applications in the cloud. We propose the MicroApp architecture that help address the difficulty in dealing with the non-uniformity. MicroApp splits a web application into multiple micro applications. Each micro application encapsulates a port of the code and data with the same level of security and integrity requirement. The micro applications will then be deployed to corresponding infrastructures that satisfy the respective requirements. MicroApp provides an RPC mechanism to allow control flows across micro applications. The architecture can be transparently applied to existing web applications and allows an application to effectively adapt to the cloud environment.
On 4-ordered 3-regular graphs
(2011-09-01)
Tsai, Ming
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Tsai, Tsung-Han
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Tan, Jimmy J. M.
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Hsu, Lih-Hsing
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資訊工程學系
A graph G is k-ordered if for any sequence of k distinct vertices nu(1), nu(2), ..., nu(k) of G there exists a cycle in G containing these k vertices in the specified order. In 1997, Ng and Schultz posed the question of the existence of 4-ordered 3-regular graphs other than the complete graph K(4) and the complete bipartite graph K(3,3). In 2008, Meszaros solved the question by proving that the Petersen graph and the Heawood graph are 4-ordered 3-regular graphs. Moreover, the generalized Honeycomb torus GHT(3, n, 1) is 4-ordered for any even integer n with n >= 8. Up to now, all the known 4-ordered 3-regular graphs are vertex transitive. Among these graphs, there are only two non-bipartite graphs, namely the complete graph K(4) and the Petersen graph. In this paper, we prove that there exists a bipartite non-vertex-transitive 4-ordered 3-regular graph of order n for any sufficiently large even integer n. Moreover, there exists a non-bipartite non-vertex-transitive 4-ordered 3-regular graph of order n for any sufficiently large even integer n. (C) 2011 Elsevier Ltd. All rights reserved.
On the Enhanced Hyper-hamiltonian Laceability of Hypercubes
(2009)
Tsai, Tsung-Han
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Kung, Tzu-Liang
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Tan, Jimmy J. M.
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Hsu, Lih-Hsing
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資訊工程學系
A bipartite graph is hamiltonian laceable if there exists a hamiltonian path between any two vertices that are in different partite sets. A hamiltonian laceable graph G is said to be hyper-hamiltonian laceable if, for any vertex v of G, there exists a hamiltonian path of G - {v} joining any two vertices that are located in the same partite set different from that of v. In this paper, we further improve the hyper-hamiltonian laceability of hypercubes by showing that, for any two vertices x, y from one partite set of Q(n), n >= 4, and any vertex w from the other partite set, there exists a hamiltonian path H of Q(n) - {w} joining x to y such that d(H)(X, Z) = l for any vertex z is an element of V(Q(n)) - {x, y, w} and for every integer l satisfying both d(Qn) (x, z) <= l <= 2(n) - 2 - d(Qn) (z, y) and 2 vertical bar(l - d(Qn) (x, z)). As a consequence, many attractive properties of hypercubes follow directly from our result.
Optimal Edge Congestion of Exchanged Hypercubes
(2016-01-01)
Tsai, Tsung-Han
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Chen, Y-Chuang
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Tan, Jimmy J. M.
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資訊工程學系
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Department of Computer Science
Topological properties have become a popular and important area of focus for studies that analyze interconnections between networks. The hypercube is one of the most widely discussed topological structures for interconnections between networks and is usually covered in introductions to the basic principles and methods for network design. The exchanged hypercube EH(s, t) is a new variant of the hypercube that has slightly more than half as many edges and retains several valuable and desirable properties of the hypercube. In this paper, we propose an approach for shortest path routing algorithms from the source vertex to the destination vertex in EH(s, t) with time complexity O(n), where n - s + t + 1 and 1 <= s <= t. We focus on edge congestion, which is an important indicator for cost analyses and performance measurements in interconnection networks. Based on our shortest path routing algorithm, we show that the edge congestion of EH(s, t) is 3.2(s+t+1) - 2(s+1) - 2(t+1). In addition, we prove that our shortest path routing algorithm is an optimal routing strategy with respect to the edge congestion of EH(s, t).
Optimal Edge Congestion of Exchanged Hypercubes
(2016-01)
Tsai, Tsung-Han
;
Chen, Y-Chuang
;
Tan, Jimmy J. M.
;
資訊工程學系
;
Department of Computer Science
Topological properties have become a popular and important area of focus for studies that analyze interconnections between networks. The hypercube is one of the most widely discussed topological structures for interconnections between networks and is usually covered in introductions to the basic principles and methods for network design. The exchanged hypercube EH(s, t) is a new variant of the hypercube that has slightly more than half as many edges and retains several valuable and desirable properties of the hypercube. In this paper, we propose an approach for shortest path routing algorithms from the source vertex to the destination vertex in EH(s, t) with time complexity O(n), where n - s + t + 1 and 1 <= s <= t. We focus on edge congestion, which is an important indicator for cost analyses and performance measurements in interconnection networks. Based on our shortest path routing algorithm, we show that the edge congestion of EH(s, t) is 3.2(s+t+1) - 2(s+1) - 2(t+1). In addition, we prove that our shortest path routing algorithm is an optimal routing strategy with respect to the edge congestion of EH(s, t).
Smart Beholder: An Extensible Smart Lens Platform
(2016)
Huang, Chun-Ying
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Fan, Ching-Ling
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Hsu, Chih-Fan
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Chang, Hsin-Yu
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Tsai, Tsung-Han
Smart Lenses refer to detachable, orientable and zoomable lenses that stream live videos over wireless networks to heterogeneous computing devices, including tablets and smartphones. Various novel applications are made possible by smart lenses, including mobile photography, smart surveillance cameras, and Unmanned Aerial Vehicle (UAV) cameras. However, to our best knowledge, existing smart lenses are closed and proprietary, and thus we initiate an open-source project called Smart Beholder for end-to-end solutions of smart lenses. The code and documents of Smart Beholder can be found at our website http://www.smartbeholder.org. Our Smart Beholder platform are useful to researchers for fast prototyping, developers for rapid development, and amateurs for hobbies. We have implemented Smart Beholder server (camera) using a popular embedded Linux platform, called Raspberry Pi. We have also realized Smart Beholder client (controller) on various OS\'s, including Android. Our experimental results show the practicality and efficiency of our proposed Smart Beholder: we outperform commercial products in the market in terms of both objective and subjective metrics. We believe the release of Smart Beholder will stimulate future studies on novel multimedia applications enabled by smart lenses.
Topological Properties on the Wide and Fault Diameters of Exchanged Hypercubes
(2014-12-01)
Tsai, Tsung-Han
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Chen, Y-Chuang
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Tan, Jimmy J. M.
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資訊工程學系
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Department of Computer Science
The n-dimensional hypercube is one of the most popular topological structure for interconnection networks in parallel computing and communication systems. The exchanged hypercube EH(s, t), a variant of the hypercube, retains several valuable and desirable properties of the hypercube such as a small diameter, bipancyclicity, and super connectivity. In this paper, we construct s + 1 (or t + 1) internally vertex-disjoint paths between any two vertices for parallel routes in the exchanged hypercube EH(s,t) for 3 <= s <= t. We also show that both the (s + 1)-wide diameter and s-fault diameter of the exchanged hypercube EH(s,t) are s + t + 3 for 3 <= s <= t.
Toward an Adaptive Screencast Platform: Measurement and Optimization
(2016-12-01)
Hsu, Chih-Fan
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Fan, Ching-Ling
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Tsai, Tsung-Han
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Huang, Chun-Ying
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Hsu, Cheng-Hsin
The binding between computing devices and displays is becoming dynamic and adaptive, and screencast technologies enable such binding over wireless networks. In this article, we design and conduct the first detailed measurement study on the performance of the state-of-the-art screencast technologies. Several commercial and one open-source screencast technologies are considered in our detailed analysis, which leads to several insights: (1) there is no single winning screencast technology, indicating room to further enhance the screencast technologies; (2) hardware video encoders significantly reduce the CPU usage at the expense of slightly higher GPU usage and end-to-end delay, and should be adopted in future screencast technologies; (3) comprehensive error resilience tools are needed as wireless communication is vulnerable to packet loss; (4) emerging video codecs designed for screen contents lead to a better Quality of Experience (QoE) of screencast; and (5) rate adaptation mechanisms are critical to avoiding degraded QoE due to network dynamics. As a case study, we propose a nonintrusive yet accurate available bandwidth estimation mechanism. Real experiments demonstrate the practicality and efficiency of our proposed solution. Our measurement methodology, open-source screencast platform, and case study allow researchers and developers to quantitatively evaluate other design considerations, which will lead to optimized screencast technologies.