indra halim | Telkom University (original) (raw)
Address: Bandung, Jawa Barat, Indonesia
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Papers by indra halim
Developmental Biology, 2010
cilia in Sox17 mutants revealed that endoderm functions in early stages of node morphogenesis. Fu... more cilia in Sox17 mutants revealed that endoderm functions in early stages of node morphogenesis. Further studies have revealed impairment of gap junctions caused by the mislocalization of the Connexin43 protein in the definitive endoderm in the mutants. These studies provide novel insights into the role of definitive endoderm in the establishment of LR asymmetric in mouse embryos.
Journal of Materials Processing Technology, 2009
Mechanical milling (MM) is referred to a solid state size reduction process where work materials ... more Mechanical milling (MM) is referred to a solid state size reduction process where work materials in the form of coarse particulates are broken into the ultimate fineness by means of mechanical impact created by collisions of the work materials and the milling media which are placed inside a reciprocating vial. Many milling techniques have been so far developed to improve the process. However, the efficiency of MM process is still below satisfactory in terms of energy balance, where the energy consumed by the process of reduction is still very low compared to the energy supplied to perform the milling process itself. This contributes to high energy losses and proportionally to the span of processing time. Other major problems inherent in the process are contamination by the balls and the vial materials into the work materials, and process temperature that could influence the properties of milled materials. Since MM process utilizes the energy generated by impact upon the collisions of the balls against the work materials, it is important to understand the motions of the balls, the work materials, and the vial, which are the sources of the generation of impact energy. To obtain an optimized processing condition, the motions of vial and ball in relationship with the work materials should be designed in such a way to ensure the optimum impact energy is consumed by the work materials for the size reduction purposes. This paper presents a physical model for work materials, balls, and vial collisions based on different ways of motions. Using this model, higher impact could be achieved. These would lead to the reduction of milling time, contamination, as well as milling temperature.
Sadhana-academy Proceedings in Engineering Sciences, 2009
This paper presents characteristics of a new catalytic converter (catco) to be used for natural g... more This paper presents characteristics of a new catalytic converter (catco) to be used for natural gas fuelled engine. The catco were developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO 2 ) and cobalt oxide (CoO) with wire mesh substrate. Both of the catalyst materials (such as TiO 2 and CoO) are inexpensive in comparison with conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metals are now identified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that the TiO 2 /CoO based catalytic converter and a new natural gas engine such as compressed natural gas (CNG) direct injection (DI) engine were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM catco) was tested for comparison purposes. The OEM catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO 2 /CoO based catalytic converter are 93%, 89% and 82% for NO x , CO and HC emissions respectively. It is calculated that the TiO 2 /CoO based catalytic converter reduces 24%, 41% and 40% higher NO x , CO and HC emissions in comparison to OEM catco respectively. The objective of this paper is to develop a low-cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low-cost catalytic converter development characteristics and CNGDI engine test results have been presented with discussions.
Developmental Biology, 2010
cilia in Sox17 mutants revealed that endoderm functions in early stages of node morphogenesis. Fu... more cilia in Sox17 mutants revealed that endoderm functions in early stages of node morphogenesis. Further studies have revealed impairment of gap junctions caused by the mislocalization of the Connexin43 protein in the definitive endoderm in the mutants. These studies provide novel insights into the role of definitive endoderm in the establishment of LR asymmetric in mouse embryos.
Journal of Materials Processing Technology, 2009
Mechanical milling (MM) is referred to a solid state size reduction process where work materials ... more Mechanical milling (MM) is referred to a solid state size reduction process where work materials in the form of coarse particulates are broken into the ultimate fineness by means of mechanical impact created by collisions of the work materials and the milling media which are placed inside a reciprocating vial. Many milling techniques have been so far developed to improve the process. However, the efficiency of MM process is still below satisfactory in terms of energy balance, where the energy consumed by the process of reduction is still very low compared to the energy supplied to perform the milling process itself. This contributes to high energy losses and proportionally to the span of processing time. Other major problems inherent in the process are contamination by the balls and the vial materials into the work materials, and process temperature that could influence the properties of milled materials. Since MM process utilizes the energy generated by impact upon the collisions of the balls against the work materials, it is important to understand the motions of the balls, the work materials, and the vial, which are the sources of the generation of impact energy. To obtain an optimized processing condition, the motions of vial and ball in relationship with the work materials should be designed in such a way to ensure the optimum impact energy is consumed by the work materials for the size reduction purposes. This paper presents a physical model for work materials, balls, and vial collisions based on different ways of motions. Using this model, higher impact could be achieved. These would lead to the reduction of milling time, contamination, as well as milling temperature.
Sadhana-academy Proceedings in Engineering Sciences, 2009
This paper presents characteristics of a new catalytic converter (catco) to be used for natural g... more This paper presents characteristics of a new catalytic converter (catco) to be used for natural gas fuelled engine. The catco were developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO 2 ) and cobalt oxide (CoO) with wire mesh substrate. Both of the catalyst materials (such as TiO 2 and CoO) are inexpensive in comparison with conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metals are now identified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that the TiO 2 /CoO based catalytic converter and a new natural gas engine such as compressed natural gas (CNG) direct injection (DI) engine were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM catco) was tested for comparison purposes. The OEM catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO 2 /CoO based catalytic converter are 93%, 89% and 82% for NO x , CO and HC emissions respectively. It is calculated that the TiO 2 /CoO based catalytic converter reduces 24%, 41% and 40% higher NO x , CO and HC emissions in comparison to OEM catco respectively. The objective of this paper is to develop a low-cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low-cost catalytic converter development characteristics and CNGDI engine test results have been presented with discussions.