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Effects of Structural Parameters on the Dynamics of a Beam Structure with a Beam-Type Vibration Absorber
Mothanna Y. Abd,Azma Putra,Nawal A. A. Jalil,Jamaludin Noorzaei
Advances in Acoustics and Vibration , 2012, DOI: 10.1155/2012/268964
Abstract: A beam-type absorber has been known as one of the dynamic vibration absorbers used to suppress excessive vibration of an engineering structure. This paper studies an absorbing beam which is attached through a visco-elastic layer on a primary beam structure. Solutions of the dynamic response are presented at the midspan of the primary and absorbing beams in simply supported edges subjected to a stationary harmonic load. The effect of structural parameters, namely, rigidity ratio, mass ratio, and damping of the layer and the structure as well as the layer stiffness on the response is investigated to reduce the vibration amplitude at the fundamental frequency of the original single primary beam. It is found that this can considerably reduce the amplitude at the corresponding troublesome frequency, but compromised situation should be noted by controlling the structural parameters. The model is also validated with measured data with reasonable agreement. 1. Introduction A beam-type absorber is one of the techniques to reduce undesirable vibration of many vibrating systems, such as a synchronous machine, mounting structure for a sensitive instrument, and other continuous structure in engineering. The absorber system usually consists of a beam attached to the host structure using an elastic element. The natural frequency of the absorber is then tuned to be the same as the troublesome operating frequency of the host structure to create counter force, which in return reduces the vibration of the structure. As beams are important structures in civil or mechanical engineering, several works have also been established to investigate the performance of the absorbing beam which is attached also to a beam structure. Among the earliest studies of the double-beam system is one proposed by Yamaguchi [1], which investigated the effectiveness of the dynamic vibration absorber consisting of double-cantilever visco-elastic beam connected by spring and viscous damper. The auxiliary beam is attached to the center of the main beam excited at its end by a sinusoidal force. It is found that the amplitude at resonances of the main beam is sensitive to the stiffness and mass of the absorbing beam. The damping ratio was formulated as a function of mass and layer stiffness of the absorber. Vu et al. [2] studied the distributed vibration absorber under stationary distributed force. A closed form was developed by utilizing change of variables and modal analysis to decouple and solve differential equations. Oniszczuk [3] studied the free vibrations of two identical parallel simply
The Characterization of Rational Alternative Cubic Curve
Azhar Ahmad,Jamaludin Md. Ali
Matematika , 2006,
Abstract: Parametric rational cubic curves to determine conditions for convex, inflections, loops, cusps and shear curves are analyzed. The rational alternative cubic curve is applied to construct the curve segment with fixed end points and end tangents. Expressing the end weights and shape parameters to be analyzed in terms of the barycentric coordinates of the shoulder point with respect to the control points, helps to determine the constraints of the curves. A method to control and preserve the segment shapes which is completely characterized by the position of its shoulder point is presented. Subsequently, it is demonstrated that for any specific shoulder point, a family of correspondent curves can be generated.
Pengawalan Lengkung Kubik Nisbah Alternatif
Azhar Ahmad,Jamaludin Md. Ali
Matematika , 2003,
Abstract: In this paper the discussion is around the topic of geometrical control of rational alternative cubic curve in computer aided geometric design (CAGD). With this method we are able to preserve convexity of curves and inflecting curves, by determining the constraints of corresponding scalar weights with respect to the control points. The rational cubic curve is characterised by two endpoints, two end slopes and an intermediate point. This study shows the weights play important role in controlling the shape of curve segment. By using the barycentric coordinate, it will make related equations and inequations easier to understand and to be manipulated.
Fitting Daily Rainfall Amount in Malaysia Using the Normal Transform Distribution
Jamaludin Suhaila,Abdul Aziz Jemain
Journal of Applied Sciences , 2007,
Abstract: This research presents a statistical study of rainfall which compares several types of normal transform distributions that describe rainfall distribution in Malaysia over a multi-year period. The normal transform distribution meaning that all tested distributions were established based on some modification or transformation of the normal distribution through several methods. The lognormal, skew normal and mixed lognormal distributions are among the normal transform distributions that are proposed and tested to identify the optimal model for daily rainfall amount in several rain gauge stations in Malaysia. The selected model will be chosen based on the minimum error produced by seven criteria of goodness of-fit (GOF) tests, namely the median of absolute difference (MAD) between the empirical and hypothesized distribution function, the traditional Empirical Distribution Function (EDF) Statistics which include Kolmogorov-Smirnov statistic D, Anderson Darling statistic A2 and Cramer-von-Mises statistic W2 and the new method of EDF Statistics based on the likelihood ratio statistics. Of the three models tested, the mixed lognormal is found to be the most appropriate distribution for describing the daily rainfall amount in Malaysia.
Introducing the Mixed Distribution in Fitting Rainfall Data  [PDF]
Jamaludin Suhaila, Kong Ching-Yee, Yusof Fadhilah, Foo Hui-Mean
Open Journal of Modern Hydrology (OJMH) , 2011, DOI: 10.4236/ojmh.2011.12002
Abstract: Several types of mixed distribution are proposed and tested in order to determine the best model in describing daily rainfall amount in Peninsular Malaysia for the time period of 33 years. A mixed distribution is a mixture of discrete and continuous daily rainfall which included the dry days. The mixed distributions tested in this study were exponential distribution, gamma distribution, weibull distribution and lognormal distribution. The model will be selected based on the Akaike Information Criterion (AIC). In general, the mixed lognormal distribution has been selected as the best model for most of the rain gauge stations in Peninsular Malaysia. However, these results are greatly influenced by the topographical, geographical and climatic changes of the rain gauge stations.
Jamaludin Ahmad,Mazila Ghazali,Aminuddin Hassan
International Journal of Instruction , 2011,
Abstract: This is a quantitative research using correlational method. The purpose of this research is to study the relationship between self concept and ability to handle stress on academic achievement of student leaders in University Putra Malaysia. The sample size consists of 106 respondents who are the Student Supreme Council and Student Representative Committee. Tennessee Self Concept Scale (TSCS) was used to evaluate respondents’ self concept and for respondents’ responses strategy the Response Strategy Questionnaire were used. The respondents’ CGPA is used to evaluate their academic achievements. The findings illustrate that there is no significant relationship between self concept and academic achievement. Correlation between self concept and academic achievement is not significant (r = 0.06, p = 0.950). Meanwhile there is a significant relationship between respondents’ response strategies and academic achievements X2 (10, N = 106) = 19.721, p = 0.032. This would mean that the respondent’s response strategy is influenced by his or her academic achievement. The value of frequency contingency, 0.396 illustrate that the relationship is positive and low. The findings from this research will provide information to those who intend to plan beneficial programs for the university or the community in general.
Parametric Surface Generation Using Partial Differential Equation Based Approach
Shahrul Nizam Ishak,Jamaludin Md Ali
Matematika , 2008,
Abstract: The main objective of this paper is to present a new parametric surface generation by introducing the sine function to the boundary condition. The work present here utilises the biharmonic equation of order four with the Bloor-Wilson PDE as the solution. Thus, to demonstrate it, an example of dint vase is illustrated.
Permukaan Sapuan Translasi Teradun
Yeap Tan Hon,M. A. Jamaludin
Matematika , 2001,
Abstract: To construct a swept surface, one generator curve and one direction are needed, with generator curve being swept along the direction. For translational swept surfaces, the direction is represented by a director curve. These generator curve and director curve will form the boundaries of the surface. For the original translational swept surface, the surface have opposite boundaries that are in the same shape. In this paper, we are going to give one method to produce a swept surface with three or four different boundaries using blendingtechnique.
Generating the Shapes of Jars using Partial Differential Equations
Nur Baini Ismail,Jamaludin Md Ali
Matematika , 2004,
Abstract: This paper presents an alternative way to generate the jars that have elliptical cross-sectional area at the top and circle cross-sectional area at the bottom of the jars by using partial differential equations.
Propeller Blade Design Using Partial Differential Equations with Three Vector Valued Shape Parameters
Zainor Ridzuan Yahya,Jamaludin Md Ali
Matematika , 2007,
Abstract: Partial differential equation (PDE) surface which is defined as a solution of a PDE has many advantages in surface blending, generation of free-form surfaces and others. In this paper, we will investigate the designing of a blade with three vector valued shape parameters. We will investigate the effect of shape parameter's change with respect to the shape of the blade used. The solution to a 4th order PDE is solved analytically with consideration of computational efficiency.
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