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All Journal Journal of the Indonesian Mathematical Society Limits: Journal of Mathematics and Its Applications Journal of Applied Mathematics and Modelling
Sri Redjeki Pudjaprasetya, Sri Redjeki
Institut Teknologi Bandung
Computer Science & IT Control & Systems Engineering Engineering Environmental Science Mathematics

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 1 
A TRAVELING PULSE BEHAVIOR OF THE SPREAD OF THE AVIAN FLU VIRUSES AMONG FLOCK AND HUMAN Pudjaprasetya, S.R.; Gunawan, A.Y.
Journal of the Indonesian Mathematical Society Volume 16 Number 1 (April 2010)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.16.1.30.39-49

Abstract

We propose two disease transmission models: the SI model with di®u-sive terms as a model for transmission of avian in°uenza viruses among °ock withconstant population density, and the host-vector SI model with di®usive terms fortransmission among °ock and human. There is a threshold number that determinewhether the diseases become epidemic or not. It depends on three parameters: theaverage length of the infective period, the contact parameter, and the density ofsusceptible population at the initial time. With di®usive terms in the model, thespatial spread of the infection is obvious. Threshold number greater than one isalso the necessary condition for the spreading of infection in the form of a travelingpulse. Its minimum velocity can be determined. We implement the MacCormackmethod, and simulate the generation of a traveling pulse starting from one infectedbird. Numerically, we obtain the percentage of survival in °ock and human afterthe epidemic. We also simulate the minimal portion of immunization in order toprevent further spread.DOI : http://dx.doi.org/10.22342/jims.16.1.30.39-49
SIMULATION OF ANALYTICAL TRANSIENT WAVE DUE TO DOWNWARD BOTTOM THRUST Tjandra, Sugih Sudharma; Pudjaprasetya, Sri Redjeki; Wiryanto, Leo Hari
Journal of the Indonesian Mathematical Society Volume 21 Number 2 (October 2015)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.21.2.189.93-104

Abstract

Generation process is an important part of understanding waves, especially tsunami. Large earthquake under the sea is one major cause of tsunamis. The sea surface deforms as a response from the sea bottom motion caused by the earthquake. Analytical description of surface wave generated by bottom motion can be obtained from the linearized dispersive model. For a bottom motion in the form of a downward motion, the result is expressed in terms of improper integral. Here, we focus on analyzing the convergence of this integral, and then the improper integral is approximated into a finite integral so that the integral can be evaluated numerically. Further, we simulate free surface elevation for three different type of bottom motions, classified as impulsive, intermediate, and slow  movements. We demonstrate that the wave propagating to the right, with a depression as the leading wave, followed with subsequent wave crests. This phenomena is often observed in most tsunami events.DOI : http://dx.doi.org/10.22342/jims.21.2.189.93-104
An Analysis of A Three-Phase Versus A Four-Phase Traffic Lights Regulation for A Four-Leg Intersection Pudjaprasetya, Sri Redjeki; Noor, Dear Michiko
Journal of the Indonesian Mathematical Society Volume 26 Number 2 (July 2020)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.26.2.823.192-201

Abstract

Traffic management of intersections is an important factor that can determine traffic density at the intersection, as well as its surrounding. Long traffic queues we encounter in daily life, were often caused by ineffectiveness of traffic lights management of the cross sections.In this article, an analytic study of traffic light management of a four-leg intersection, based on the kinematic LWR model, was presented. Comparison was based on observing the end of queues over three cycles of red-green lights, under the assumption of a constant traffic flux. On every leg of the intersection, the end of the queues were obtained from characteristic lines of the shock waves.From these observations, the three phase regulation was preferred over the four-phase one. Finally, a case study of Taman Sari - Baltos intersection located in Bandung City, Indonesia, was discussed. Parameter values used in these simulations were obtained from direct observation. 
SIMULATION OF ANALYTICAL TRANSIENT WAVE DUE TO DOWNWARD BOTTOM THRUST Sugih Sudharma Tjandra; Sri Redjeki Pudjaprasetya; Leo Hari Wiryanto
Journal of the Indonesian Mathematical Society Volume 21 Number 2 (October 2015)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.21.2.189.93-104

Abstract

Generation process is an important part of understanding waves, especially tsunami. Large earthquake under the sea is one major cause of tsunamis. The sea surface deforms as a response from the sea bottom motion caused by the earthquake. Analytical description of surface wave generated by bottom motion can be obtained from the linearized dispersive model. For a bottom motion in the form of a downward motion, the result is expressed in terms of improper integral. Here, we focus on analyzing the convergence of this integral, and then the improper integral is approximated into a finite integral so that the integral can be evaluated numerically. Further, we simulate free surface elevation for three different type of bottom motions, classified as impulsive, intermediate, and slow  movements. We demonstrate that the wave propagating to the right, with a depression as the leading wave, followed with subsequent wave crests. This phenomena is often observed in most tsunami events.DOI : http://dx.doi.org/10.22342/jims.21.2.189.93-104
An Analysis of A Three-Phase Versus A Four-Phase Traffic Lights Regulation for A Four-Leg Intersection Sri Redjeki Pudjaprasetya; Dear Michiko Noor
Journal of the Indonesian Mathematical Society Volume 26 Number 2 (July 2020)
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.26.2.823.192-201

Abstract

Traffic management of intersections is an important factor that can determine traffic density at the intersection, as well as its surrounding. Long traffic queues we encounter in daily life, were often caused by ineffectiveness of traffic lights management of the cross sections.In this article, an analytic study of traffic light management of a four-leg intersection, based on the kinematic LWR model, was presented. Comparison was based on observing the end of queues over three cycles of red-green lights, under the assumption of a constant traffic flux. On every leg of the intersection, the end of the queues were obtained from characteristic lines of the shock waves.From these observations, the three phase regulation was preferred over the four-phase one. Finally, a case study of Taman Sari - Baltos intersection located in Bandung City, Indonesia, was discussed. Parameter values used in these simulations were obtained from direct observation. 
Simulation of Tsunami Waves Generated by Landslide Movements on a Flat Bottom Sulvianuri, Rani; Setyowisnu, Glagah Eskacakra; Pudjaprasetya, Sri Redjeki
Journal of the Indonesian Mathematical Society Vol. 31 No. 1 (2025): MARCH
Publisher : IndoMS

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.22342/jims.v31i1.1897

Abstract

Disasters like tsunamis are typically triggered by tectonic earthquakes, volcanic eruptions, or landslides. Tsunami waves can hit the coast with enormous energy, causing great damage. This study focuses on landslide-generated wave phenomena; the analytical formula of the linear dispersive model is adopted and used to simulate the development of free surface waves due to bottom landslides. Various types of landslide motion were simulated over a flat bottom depth and the resulting surface wave forms were examined and compared with the far-field leading wave type of solution. In addition, the effect of wave dispersion on the resulting wave pattern was investigated.
FFT - Based Watermarking for Copyright Protection of Color Image Joshua Febrian Wiranata; Sri Redjeki Pudjaprasetya; Pritta Etriana Putri; Riski Kurniawan
Journal of Applied Mathematics and Modelling Vol. 1 No. 1 (2025): Journal of Applied Mathematics and Modelling
Publisher : CIB Nusantara

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.64570/jamm.v1i1.1

Abstract

Watermarks are commonly used by authors to prevent unauthorized copying and to protect their intellectual property. When a watermark is applied to a digital image, it is expected that the watermark will not be visible, and the watermark will retain its good quality when extracted. This paper is focused on one type of color image watermarking method, using the Fast Fourier Transform (FFT) algorithm. In this algorithm, the watermark is embedded in the frequency domain of the image. In this way, our watermark algorithm exhibits good quality and demonstrates strong resistance against common attacks. Here, we experimented with compression, blur, object addition, and noise addition.
Skema Staggered Grid pada Persamaan Air Dangkal untuk Simulasi Aliran di Sekitar Pulau Nashrul Millah; Sri Redjeki Pudjaprasetya
Limits: Journal of Mathematics and Its Applications Vol. 21 No. 1 (2024): Limits: Journal of Mathematics and Its Applications Volume 21 Nomor 1 Edisi Ma
Publisher : Pusat Publikasi Ilmiah LPPM Institut Teknologi Sepuluh Nopember

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Wake merupakan suatu pola gelombang pada permukaan air yang muncul akibat adanya pergerakan benda rigid. Pada penelitian ini, skema staggered grid orde dua digunakan untuk menyelesaikan persamaan air dangkal tak linier. Hasil yang didapat digunakan untuk mensimulasikan munculnya riak yang timbul akibat adanya arus yang menabrak pulau berbentuk lingkaran. Pada simulasi ini gaya-gaya luar yang diperhitungkan adalah gangguan angin, gaya gesek dengan dasar, dan efek turbulensi. Simulasi dilakukan dengan meniupkan angin pada ujunga kanal memanjang dengan sebuah pulau di dekat pangkalnya yang memicu aliran air. Untuk bilangan Reynold yang kecil, aliran air bersifat laminar dan membentuk pola halus di sekitar pulau. Bilangan Reynold merupakan perbandingan antara ketaklinieran dengan viskositas air. Untuk simulasi dengan bilangan Reynold yang besar, aliran menjadi tidak stabil dan memicu munculnya riak turbulen. Pusaran air tampak pada riak yang muncul di belakang pulau.
Co-Authors A.Y. Gunawan Dear Michiko Mutiara Noor Joshua Febrian Wiranata Leo Hari Wiryanto Nashrul Millah Pritta Etriana Putri Riski Kurniawan Setyowisnu, Glagah Eskacakra Sugih Sudharma Tjandra, Sugih Sudharma Sulvianuri, Rani