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Free vibration analysis of a non-uniform beam with multiple point masses
Wu, Jong-Shyong,Hsieh, Mang Techno-Press 2000 Structural Engineering and Mechanics, An Int'l Jou Vol.9 No.5
The natural frequencies and the corresponding mode shapes of a non-uniform beam carrying multiple point masses are determined by using the analytical-and-numerical-combined method. To confirm the reliability of the last approach, all the presented results are compared with those obtained from the existing literature or the conventional finite element method and close agreement is achieved. For a "uniform" beam, the natural frequencies and mode shapes of the "clamped-hinged" beam are exactly equal to those of the "hinged-clamped" beam so that one eigenvalue equation is available for two boundary conditions, but this is not true for a "non-uniform" beam. To improve this drawback, a simple transformation function ${\varphi}({\xi})=(e+{\xi}{\alpha})^2$ is presented. Where ${\xi}=x/L$ is the ratio of the axial coordinate x to the beam length L, ${\alpha}$ is a taper constant for the non-uniform beam, e=1.0 for "positive" taper and e=1.0+$|{\alpha}|$ for "negative" taper (where $|{\alpha}|$ is the absolute value of ${\alpha}$). Based on the last function, the eigenvalue equation for a non-uniform beam with "positive" taper (with increasingly varying stiffness) is also available for that with "negative" taper (with decreasingly varying stiffness) so that half of the effort may be saved. For the purpose of comparison, the eigenvalue equations for a positively-tapered beam with five types of boundary conditions are derived. Besides, a general expression for the "normal" mode shapes of the non-uniform beam is also presented.
Neuropsychopharmacological Understanding for Therapeutic Application of Morphinans
신은주,Jau-Shyong Hong,김형춘 대한약학회 2010 Archives of Pharmacal Research Vol.33 No.10
Morphinans are a class of compounds containing the basic structure of morphine. It is wellknown that morphinans possess diverse pharmacological effects on the central nervous system. This review will demonstrate novel neuroprotective effects of several morphinans such as, dextromethorphan, its analogs and naloxone on the models of multiple neurodegenerative disease by modulating glial activation associated with the production of a host of proinflammatory and neurotoxic factors, although dextromethorphan possesses neuropsycotoxic potentials. The neuroprotective effects and the therapeutic potential for the treatment of excitotoxic and inflammatory neurodegenerative diseases, and underlying mechanism of morphinans are discussed.
Impact Evaluation of DDoS Attacks on DNS Cache Server Using Queuing Model
( Zheng Wang ),( Shian-shyong Tseng ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.4
Distributed Denial-of-Service (DDoS) attacks towards name servers of the Domain Name System (DNS) have threaten to disrupt this critical service. This paper studies the vulnerability of the cache server to the flooding DNS query traffic. As the resolution service provided by cache server, the incoming DNS requests, even the massive attacking traffic, are maintained in the waiting queue. The sojourn of requests lasts until the corresponding responses are returned from the authoritative server or time out. The victim cache server is thus overloaded by the pounding traffic and thereafter goes down. The impact of such attacks is analyzed via the model of queuing process in both cache server and authoritative server. Some specific limits hold for this practical dual queuing process, such as the limited sojourn time in the queue of cache server and the independence of the two queuing processes. The analytical results are presented to evaluate the impact of DDoS attacks on cache server. Finally, numerical results are provided for further analysis.
CONVEXITY CONTROL AND APPROXIMATION PROPERTIES OF INTERPOLATING CURVES
Qi, Duan,Chen, Tzer-Shyong,Djidjeli, K.,Price, W.G.,Twizell, E.H. 한국전산응용수학회 2000 Journal of applied mathematics & informatics Vol.7 No.2
A constrained rational cubic spline with linear denominator was constructed in [1]. In the present paper, the sufficient condition for convex interpolation and some properties in error estimation are given.
Sliding Mode Stabilization of a Centrifugal Compress or with Spool Dynamics
Chau-Chung Song,Song-Shyong Chen,Der-Cherng Liaw 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this paper, the topic of robust stabilization of a centrifugal compress or with spool dynamics is studied and presented. Sliding mode controls for systems with matching-type and mismatching-type uncertainties are seperately designed and verified. The sliding mode design is chosen to achieve the stability of the working equili brium for systems without uncertainties. However, it is known that uncertainties in the spool dynamics and the compress or characteristic are most likely to happen in the real applications. By actuating only the throttle as the single control input, the robust stabilization of the working equili brium is proposed by using as liding mode control. Numerical simulations are given to demonstrate the feasibility of the proposed and derived approaches.