Judul: Karakteristik Minyak Sawit Kasar Selama Penyimpanan dan Pengaliran
Abstrak: Crude palm oil (CPO) is one of Indonesia's main commodity. Nowadays, Indonesia is the largest CPO producer in the world. To increase the competitiveness of CPO in Indonesia, handling, storage, and transportation of CPO should be managed efficiently. The objective of this research was to obtain the basic data about the quality characteristics and rheological properties of CPO during storage and pipe flow transportation. The quality parameters of CPO that observed in this study were free fatty acids (FFA), iodine value, carotenoid content, and the deterioration of bleachability index (DOBI). The observed parameters of the rheological properties were flow behavior index (n) and consistency index (K). CPO that used in this research had 3.44% of FFA, 52.64 of iodine value, 816 ppm of carotenoid content, and 3.21 of DOBI. CPO was stored at the storage temperature of 20, 25, 30, 35, and 40 oC over 4 weeks. The results showed that during storage, FFA levels increased, while the carotenoid content and DOBI decreased. The higher storage temperature resulted in higher rate of decline in CPO quality. At each storage temperature, the longer storage resulted in decreased quality of CPO. Based on this research, the best storage temperature to maintain the quality of CPO was at 20 oC. At the room temperature, CPO was pseudoplastic (0<n<1 and K>0), but at the higher storage temperature, CPO had rheological properties that closer to Newtonian (n=1 and K>0). The analysis of rheological properties during storage showed that storage time had no effect on the rheological properties of CPO. Study on CPO flow by using circulated pipeline in isothermal conditions showed that melting temperature was the critical temperature for maintaining low viscosity to assure the flow of CPO. Flow of CPO in high temperature caused decreasing in quality of CPO significantly.
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Judul: Characteristics of crude palm oil and their control techniques design to support the development of pipeline mode transportation
Abstrak: Indonesia is the largest producer and exporter of crude palm oil (CPO) in the world. CPO usually transported from palm oil factory to the storage tank by using tank truck. This mode of transportation is less efficient, and should be replaced by more efficient mode of transportation such as pipeline mode. Engineering principles must be applied in CPO’s pipeline mode transportation, which need basic data related to flow properties of CPO. This research was conducted to obtain basic data on the characteristics of CPO related to flow properties, and also to design their control techniques in order to support and strengthen the engineering approaches for the development of pipeline mode transportation of CPO. The research consisted of (1) study on CPO’s quality and physical properties; (2) study on the effect of temperature on physical properties of CPO; (3) study on rheological and crystallization properties of CPO in dynamic conditions; and (4) study on control techniques design of CPO’s pipeline mode transportation. CPO samples had variety on their quality attributes dan physical properties. There was good correlation between iodine values of CPO to the rheological properties of CPO at 25°C. Density, solid fat content (SFC), and rheological properties of CPO were influenced by temperature. Method of temperature preconditioning, determined the rheological properties of CPO. The flow properties of CPO samples equilibrated for 24 hour has shifted from Newtonian behaviour (detected in 55 to 45 oC) to become pseudoplastic (detected in 40 to 25 oC). CPO samples without equilibration with cooling rate from 55 oC to the measurement temperatures, had Newtonian behaviour until temperature of 30 oC. Temperature cycles in the rate of 1oC/minute between 25-55 oC affected the entalphy, SFC, and apparent viscosity () reversibly. Cooling rate and shear rate from 55 oC to 30 oC had no influence on  as long as the temperature of CPO were not reach isothermal conditions, with maximum  in 30 oC about 60 mPa.s. Study on CPO flow by using circulated pipeline in isothermal conditions showed that non-isothermal condition below its melting point (TM) must be controlled for maintaining low  of CPO. Rheology and crystallization properties of CPO can be controlled along the pipeline by using two flow systems: (A) isothermal flow system for transporting CPO in short distance in any temperature above 40 to 55 oC maintained by insulation system; and (B) non-isothermal flow system from 55 oC to the minimun temperature of 30 oC before isothermal condition, for transporting CPO in long distance, which controlled by insulation system and some heating stations in several points along the pipeline. Data of CPO’s characteristics and their control techniques design resulted from this research is very useful for the development of CPO’s pipeline mode transportation.
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Judul: Dynamical System of Hepatitis B in Three Groups with Vaccination
Abstrak: The aim of this study is to modify the hepatitis B transmission model in three age groups involving vaccination from the model conducted by Zhoe and Zhang.The method used is to analyze the stability of the fixed point and its basic reproduction number (R_0). Performed stability analysis and numerical simulation to see population dynamics. Next, a sensitivity analysis of the parameters was carried out to see its effect on R_0. From the analysis obtained two fixed points, namely non-endemic and endemic fixed points. Non-endemic fixed points are locally asymptotically stable if R_0 <1 Meanwhile, the endemic fixed point is locally asymptotically stable if R_0 > 1. Hepatitis vaccination affects the number of susceptible population, because the more successful the vaccination, the smaller the number of susceptible populations so that the smaller the population will be infected.
Keyword: Dynamic, Hepatitis B, Vaccine, Mathematical model