Journal of the Indonesian Mathematical Society
Journal of the Indonesian Mathematical Society disseminates new research results in all areas of mathematics and their applications. Besides research articles, the journal also receives survey papers that stimulate research in mathematics and their applications.
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INVARIANT RANDOM APPROXIMATION IN NONCONVEX DOMAIN
Shrivastava, R.;
Nashine, H. K.;
Dewangan, C. L.
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.45.69-77
Random fixed point results in the setup of compact and weakly compact domain of Banach spaces which is not necessary starshaped have been obtained in the present work. Invariant random approximation results have also been determined asits application. In this way, random version of invariant approximation results due toMukherjee and Som [13] and Singh [17] have been given.DOI :Â http://dx.doi.org/10.22342/jims.15.2.45.69-77
TWO-NORM CONTINUOUS FUNCTIONALS ON L∞
Indrati, Ch. Rini
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.47.91-96
"Pdf File"DOI :Â http://dx.doi.org/10.22342/jims.15.2.47.91-96
ROBUST DECLINE CURVE ANALYSIS
Darwis, Sutawanir;
Ruchjana, Budi Nurani;
Permadi, Asep Kurnia
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.50.105-111
Empirical decline curve analysis of oil production data gives reasonable answer in hyperbolic type curves situations; however the methodology has limitations in fitting real historical production data in present of unusual observations due to the effect of the treatment to the well in order to increase production capacity. The development ofrobust least squares offers new possibilities in better fitting production data using declinecurve analysis by down weighting the unusual observations. This paper proposes a robustleast squares fitting lmRobMM approach to estimate the decline rate of daily production data and compares the results with reservoir simulation results. For case study, we usethe oil production data at TBA Field West Java. The results demonstrated that theapproach is suitable for decline curve fitting and offers a new insight in decline curve analysis in the present of unusual observations.DOI :Â http://dx.doi.org/10.22342/jims.15.2.50.105-111
ON MINIMUM AND MAXIMUM OF FUNCTIONS OF SMALL BAIRE CLASSES
Zulijanto, Atok
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.51.113-118
"PDF File"DOI :Â http://dx.doi.org/10.22342/jims.15.2.51.113-118
PARAMETRIC EXCITATION IN A SELF-EXCITED THREE-DEGREES OF FREEDOM PROBLEM
FATIMAH, SITI
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.48.97-104
The efect of parametric excitation in self-excited has been investigated in two-degrees of freedom problems. The possibility of suppressing self-excited vibrationsby using parametric excitation and the dynamic behavior of those kind systems were discussed. In the this paper, we consider a system in three-degrees of freedom problem which by using a linear transformation the system becomes an Autoparametric. The system consists of a central mass and two external masses where those masses are conectedby springs with the same constant stiffness. The flow-generated self-excited force is actingon the external masses, it is represented by Rayleigh force. The variable stiffness isperiodically varying in time, represents a parametric excitation. It turns out that forcertain parameter ranges full vibration cancellation is possible. The analysis of linearcase of system shows that there are two conditions in order to obtain an interval ofthe parametric excitation. Using the averaging method the fully non-linear system is investigated producing as non-trivial solutions unstable periodic solutions. The behaviorof this unstable solution is studied in the full system.DOI :Â http://dx.doi.org/10.22342/jims.15.2.48.97-104
INVARIANT RANDOM APPROXIMATION IN NONCONVEX DOMAIN
R. Shrivastava;
H. K. Nashine;
C. L. Dewangan
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.45.69-77
Random fixed point results in the setup of compact and weakly compact domain of Banach spaces which is not necessary starshaped have been obtained in the present work. Invariant random approximation results have also been determined asits application. In this way, random version of invariant approximation results due toMukherjee and Som [13] and Singh [17] have been given.DOI : http://dx.doi.org/10.22342/jims.15.2.45.69-77
TWO-NORM CONTINUOUS FUNCTIONALS ON L∞
Ch. Rini Indrati
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.47.91-96
"Pdf File"DOI : http://dx.doi.org/10.22342/jims.15.2.47.91-96
PARAMETRIC EXCITATION IN A SELF-EXCITED THREE-DEGREES OF FREEDOM PROBLEM
SITI FATIMAH
Journal of the Indonesian Mathematical Society Volume 15 Number 2 (October 2009)
Publisher : IndoMS
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DOI: 10.22342/jims.15.2.48.97-104
The efect of parametric excitation in self-excited has been investigated in two-degrees of freedom problems. The possibility of suppressing self-excited vibrationsby using parametric excitation and the dynamic behavior of those kind systems were discussed. In the this paper, we consider a system in three-degrees of freedom problem which by using a linear transformation the system becomes an Autoparametric. The system consists of a central mass and two external masses where those masses are conectedby springs with the same constant stiffness. The flow-generated self-excited force is actingon the external masses, it is represented by Rayleigh force. The variable stiffness isperiodically varying in time, represents a parametric excitation. It turns out that forcertain parameter ranges full vibration cancellation is possible. The analysis of linearcase of system shows that there are two conditions in order to obtain an interval ofthe parametric excitation. Using the averaging method the fully non-linear system is investigated producing as non-trivial solutions unstable periodic solutions. The behaviorof this unstable solution is studied in the full system.DOI : http://dx.doi.org/10.22342/jims.15.2.48.97-104