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Rancang Bangun Alat Eksperimen Sederhana Gerak Proyektil Wijaya, Pradita Adnan; Fauzi, Umar; Latief, Fourier Dzar Eljabbar; Firdaus, M. Thoha
Jurnal Riset dan Kajian Pendidikan Fisika Vol 4, No 1 (2017): April 2017
Publisher : Universitas Ahmad Dahlan

Menentukan gerak proyektil merupakan permasalahan penting dalam sejarah perkembangan ilmu mekanika. Gerak proyektil adalah gerak suatu benda yang diberi kecepatan awal, kemudian menempuh lintasan yang arahnya sepenuhnya dipengaruhi oleh percepatan gravitasi dan hambatan udara. Untuk mempermudah pemahaman peserta didik mengenai materi gerak proyektil, telah dibuat suatu alat eksperimen gerak proyektil sederhana. Diharapkan alat ini dapat digunakan sebagai media pembelajaran yang mudah diaplikasikan, ditiru dan terjangkau bagi pihak sekolah maupun lembaga pendidikan.Â Determining projectile motion is an important issue in the history of the development of mechanics. The motion of a projectile is the motion of an object given the initial velocity, then travels the path whose direction is completely influenced by the acceleration of gravity and air resistance. To facilitate students understanding of projectile motion material, a simple projectile motion experiments tool has been developed. It is expected that this tool can be used as a learning media that is easy to apply, imitated and affordable for schools and educational institutions.

ANNOTATION OF USING BOREHOLE TIME-LAPSE GRAVITY BY GENETIC ALGORITHM INVERSION FOR SUBSURFACE MODELING Gunawan, Indra; Wahyudi, Eko Januari; Alawiyah, Susanti; Kadir, Wawan Gunawan Abdul; Fauzi, Umar
Journal of Engineering and Technological Sciences Vol 52, No 2 (2020)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2020.52.2.2

We present the annotation to a genetic algorithm (GA) method for an inverse synthetic subsurface density model using surface and borehole time-lapse gravity data. The objective of the inversion is to find the boundaries of the object area and background, where one bit of the chromosome represents the densities. The model that was used in this paper was a simple homogeneous body anomaly and a simplified real water mass injection model in order to argue that the code is suitable for field modeling. We show the influences of the existence of borehole gravity data and location towards the inversion, where the result indicates that an additional good borehole location could increase the success rate up to 13.33% compared to without gravity borehole data for the simple model and up to 4.39% for the field model. The inversion produced the best results when the borehole positions were placed in a state of symmetry towards the body object?s mass.

Annotation of Using Borehole Time-Lapse Gravity by Genetic Algorithm Inversion for Subsurface Modeling Indra Gunawan; Eko Januari Wahyudi; Susanti Alawiyah; Wawan Gunawan Abdul Kadir; Umar Fauzi
Journal of Engineering and Technological Sciences Vol. 52 No. 2 (2020)
Publisher : Institute for Research and Community Services, Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.eng.technol.sci.2020.52.2.2

We present the annotation to a genetic algorithm (GA) method for an inverse synthetic subsurface density model using surface and borehole time-lapse gravity data. The objective of the inversion is to find the boundaries of the object area and background, where one bit of the chromosome represents the densities. The model that was used in this paper was a simple homogeneous body anomaly and a simplified real water mass injection model in order to argue that the code is suitable for field modeling. We show the influences of the existence of borehole gravity data and location towards the inversion, where the result indicates that an additional good borehole location could increase the success rate up to 13.33% compared to without gravity borehole data for the simple model and up to 4.39% for the field model. The inversion produced the best results when the borehole positions were placed in a state of symmetry towards the body object's mass.

Rancang Bangun Alat Eksperimen Sederhana Gerak Proyektil Pradita Adnan Wijaya; Umar Fauzi; Fourier Dzar Eljabbar Latief; M. Thoha Firdaus
Jurnal Riset dan Kajian Pendidikan Fisika Vol 4, No 1 (2017): April 2017
Publisher : Universitas Ahmad Dahlan

Menentukan gerak proyektil merupakan permasalahan penting dalam sejarah perkembangan ilmu mekanika. Gerak proyektil adalah gerak suatu benda yang diberi kecepatan awal, kemudian menempuh lintasan yang arahnya sepenuhnya dipengaruhi oleh percepatan gravitasi dan hambatan udara. Untuk mempermudah pemahaman peserta didik mengenai materi gerak proyektil, telah dibuat suatu alat eksperimen gerak proyektil sederhana. Diharapkan alat ini dapat digunakan sebagai media pembelajaran yang mudah diaplikasikan, ditiru dan terjangkau bagi pihak sekolah maupun lembaga pendidikan. Determining projectile motion is an important issue in the history of the development of mechanics. The motion of a projectile is the motion of an object given the initial velocity, then travels the path whose direction is completely influenced by the acceleration of gravity and air resistance. To facilitate students' understanding of projectile motion material, a simple projectile motion experiments tool has been developed. It is expected that this tool can be used as a learning media that is easy to apply, imitated and affordable for schools and educational institutions.

Permeability Estimation Based on Pore Radius and Its Distribution Umar Fauzi
Indonesian Journal of Physics Vol 13 No 1 (2002): Vol. 13 No.1, Januari 2002
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (107.89 KB)

Hydraulic permeability may be expressed as a function of pore radius. A simple capillary model shows that permeability is proportional to the square of pore radius. This model may be extended by including pore size distribution, so statistical parameters of its pore radius distribution can be considered in permeability estimation. Another recent approach, the so-called effective medium approximation uses pore radius distribution as an input parameter for permeability calculation. Permeability can be estimated with the help of the above approaches as far as the pore radius and its distribution are available. Pore radius distribution can be generated using digital image processing. By defining pore radius as the ratio of image pore area and its circumference, pore size distribution of rock image can then be created. Estimation of permeability by means of the effective medium approximation gives better results than the simple capillary model as well as its extended formulae. Definition of pore radius has however significant influence on the results of estimation, since different definitions of pore radius produces different distributions.

Physical and Lattice Gas Automata Fluid Flow Modeling in Real Porous Media Umar Fauzi; Mulyadi Mulyadi; A. S. Bahri
Indonesian Journal of Physics Vol 16 No 3 (2005): Vol. 16 No. 3, July 2005
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (413.745 KB)

Physical modeling of fluid flow in real porous media was conducted to validate Lattice-gas Automata (LGA) method. Direct observation of fluid flow was carried out on a pond with obstacles in laboratory scale. Velocity patterns of fluid flow were derived using tracer observed from images. A good agreement of velocity pattern was shown in physical and LGA modeling. This method can be used as a validation technique for numerical modeling of complex structure of porous media. The validated LGA method was a then applied to model fluid flow in real rocks. Digital image of real rocks were created from thin sections by means of image processing technique. The rock image was then used as a medium for fluid flow modeling. Investigation of effective porosity, tortuosity, and permeability can be carried out easier with the help of LGA method. Low velocity pattern shown in the model can be interpreted as non-effective porosity, since it does not have any significant contribution to the fluid flow. Effective porosity depends strongly on direction of the fluid flow.

Performance Analysis of 2D and 3D Fluid Flow Modelling Using Lattice Boltzmann Method Fourier Dzar Eljabbar Latief; Umar Fauzi
Indonesian Journal of Physics Vol 18 No 2 (2007): Vol. 18 No. 2 April 2007
Publisher : Institut Teknologi Bandung

Several studies have been conducted to observe properties of fluid flow in materials using the Lattice Boltzman Method (LBM). There are two widely used lattice model, the D2Q9 for the 2D simulation, and the D3Q19 for the 3D simulation. Our particular interest is to study the velocity map both using the 2D and the 3D simulation, using the same object. The aim of this study is to evaluate effectiveness and efficiency of both methods. In our simulation, the velocity profile between the 2D and 3D models differs greatly (mean error 30.4%) if the object has complex lateral structure (the shape along the z-axes differs greatly), while for the less complex object, the profile has only 1.4% of mean error. The computing time for the 3D model took 13 times longer than the simulation of the 2D model. The result from the comparison of both methods concludes that the simplification of fluid flow simulation of 3D objects into 2D objects should be taken carefully, for in some cases, the simplification is not quite appropriate.

Microstructure Characterization of Pigeon Hole Rock Models at Different Scale: A Preliminary Study Umar Fauzi
Indonesian Journal of Physics Vol 18 No 3 (2007): Vol. 18 No. 3 July 2007
Publisher : Institut Teknologi Bandung

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (161.618 KB)

Microstructure of rocks determines physical properties of rocks at different scale, i.e.: from micro to giga scales. Study on microstructure characterization of rock models at different scale is conducted in this research. Rock models are generated using fractal pigeon hole models at zero level. Substructure ratio selected in this study is 22 with quotient of self-similarity equals to 0.25. Porosity of created models varies from 4 to 20%. Physical parameters, i.e.: porosity, specific surface area and two point correlation functions as well as hydraulic radius distribution, are evaluated for different pixel length. Physical parameters at small scales tend to have large deviation. The deviation decreases as the pixel length increases and tends to a similar value or trend at a specific length. This study shows that some characteristic lengths are available at several rock models.

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