COMPOSITION, STRUCTURE, CORRELATION AND LOCAL WISDOM OF ULIN (Eusideroxylon zwageri Teijsm. & Binn.) IN TAU LUMBIS- NORT BORNEO

The species of iron wood or locally known as ulin/tahas, is recognized as strong and durable. This study aims to provide information about condition and corelation of iron woods in natural forests of Tau Lumbis area, including its utilization and conservation through local knowledge of Dayak Akolod and Tagol tribes. The study was conducted in natural forests in Kabungolor and Kabalob (North Kalimantan). It used a plot and selected ulin tree as the midpoint of the plot. Each trees with diameter > 10 cm in the plot were measured for its stem circumference at ±1.3 m from the ground. There were 13 individuals/ha of ulin trees in Kabalob plot and 25 individuals/ha of ulin trees in Kabungolor plot (an average of ±19 individuals/ha). Based on the density measurements, there were no correlation between ulin tree and other trees species in the two locations. The iron woods were used for various needs from generation to generation by the Dayak Akolod and DTagol tribes without paying much of attention to its conservation

CO-PYROLYSIS CANGKANG KELAPA SAWIT DAN LIMBAH PLASTIK KEMASAN

In the present study, the co-pyrolysis of biomass waste, i.e. palm kernel shells (PKS) and industrial packaging plastic waste, namely polyethylene terephthalate (PET) and polyethylene (PE) were conducted. Prior to the pyrolysis, the raw materials were analyzed by thermogravimetric and elemental procedures. The pyrolysis was conducted in a fixed bed reactor which was heated from room temperature to 500 °C in an N2 atmosphere with a heating rate of 10 °C/min. The raw materials were weighted and mixed together manually with variations of weight composition ratios between biomass and plastic, i.e. 100% biomass (100/0); 90% biomass and 10% plastic (90/10); 70% biomass and 30% plastic (70/30); 50% biomass and 50% plastic (50/50); and 100% plastic (0/100). Then, they were put under pressure to obtain a pellet. The synergistic effect of biomass and plastic was investigated to see the difference between the pyrolysis products yields in theory and experiment. The bio-oil products were characterized by several methods and showed the potential to be used as a fuel. The optimum condition was obtained from 50/50 weight composition ratio. It was gained 30% improvement of the higher heating value of bio-oil, and the percentage area of hydrocarbon was contained in bio-oil increased from 4.68% to 53.40%

Eddy Currents Variablity from Satellite Altimetry and Its Relation to Physical Conditions of Java Sea

Current pattern in Java Sea highly depends on monsoonal cycles, which create alternating conditions according to the seasons throughout the year and potential impacts on eddy currents variability. Using the surface geostrophic current data from satellite altimetry during 2013-2017, this study aims to understand the variability of eddy currents and its relations to the physical condition of the Java Sea such as sea surface temperature (SST), sea surface height (SSH), and chlorophyll-a concentration (CHL). Results showed 60 occurrence of eddy currents in the study area, 40 cyclonic and 20 anticyclonic. The largest cyclonic eddy observed in April 2013 (112.05, -5.37) with a diameter of 134.07 km, while the largest anticyclonic eddy observed in October 2017 (114.54, -6.24) with a diameter of 159.69 km. Cyclonic eddy has lower SSH and cold core while anticyclonic eddy has higher SSH and warm core. Despite having an unclear pattern during the five years period, the occurence of Eddy current has a potentially indirect influence on Chl-a concentration

SINTESIS, PENGUJIAN, DAN KARAKTERISASI HIDROGEL BERBASIS SODIUM CARBOXYMETHYL CELLULOSE DAN CHITOSAN

Hydrogel, as a water super absorbent polymer, has a potential to improve irrigation efficiency in agricultural land. The objective of this research was to optimize hydrogel syntheses using environmentally friendly natural polymers, including sodium carboxymethyl cellulose (NaCMC), chitosan, and citric acid. Hydrogel was synthesized using the hydrothermal method at a temperature below 100 °C and using water as the primary medium. The results of this research showed that hydrogel which was synthesized with 2% w/v of NaCMC and 5% w/w of citric acid in 10% v/v of chitosan, which was cross-linked in 80 °C for 2 hours, was able to absorb water up to 350 times of its dry weights for 30 minutes. The maximum absorption rate of the produced hydrogel was up to 55 grams per minutes and was achieved during the first 3 minutes of free absorbency test

COMPARISON OF RAYLEIGH WAVE CHARACTERISTICS ON SUPERCONDUCTING GRAVIMETER AND SESIMOMETER LHZ RECORDINGS

The vibrations of an earthquake can be properly recorded by the gravimeter. As a Gravimeter, Superconducting Gravimeter (SG) has a very high accuracy; slightly different with general gravimeter. Rayleigh wave is the wave with the largest amplitude in earthquake, so it will be clear on SG tape.  In this research, we use certain superconducting gravimeter (SG) and Seismometer LHZ, spread over several locations around the world; just to know more about Mw > 6 earthquake. Tidal value reduction were applied on SG’s recording in order  to get true gravity value. Then we did time-integral to get velocity and displacement. By using spectrogram function, we can display frequency of SG and LHZ. The amplitude of the Rayleigh wave recorded on the SG is smaller than that recorded on the LHZ and has signal correlation > 7.0. In any case of Rayleigh Global waves, SG is able to record clearly the phase of Rayleigh wave to R7 phase. While LHZ only records up to the R5 phase. The spectrograph analysis reinforces the differences in the viewing screens of SG and LHZ Rayleigh Global waves in the frequency domain, R7 recorded on SG has a frequency range of 0.002 Hz to 0.006 Hz. Based on the results of Rayleigh wave analysis on the SG record and its comparison with the LHZ record it can be concluded that SG has a high level of sensitivity and stable when recording Rayleigh waves

A STUDY OF STRESS CORROSION CRACKING RESISTANCE FOR COLD FORMING PLASTIC DEFORMED Cu-30Zn ALLOY

Cu-30Zn alloy has good atmospheric corrosion resistance. It is mainly used as automotive radiator cores, ammunition component, lamp fixture, flashlight shells and kickplates. Cold rolled Cu-30Zn with deformation degree 33,87% at 300OC was tested its Stress Corrosion Cracking (SCC) property. Stress corrosion cracking (SCC) of a Cu–30Zn has been investigated using Mattsson solutions 0,5 M (NH4)2SO4 + 0,05 M CuSO4 in room temperature by using a constant load method. Cu-30Zn has a weakness on stress corrosion cracking in ammonia environment (mattson solution). Scanning electron microscope (SEM) testing indicated the failure of cold roll Cu-30Zn was a transgranular cracking. Furthermore, cracking occued at stress below yield stress. Energy dispersive Spectroscopy (EDS) test exhibited dezincification indication on fracture surface. The visual examination of surface morphology on alloy showed discoloration from yellow to red. Homogenized Cu-30Zn showed better SCC resistance than cold rolled Cu-30Zn

ANALYSIS OF CLIMATOLOGICAL THERMAL COMFORT IN DKI JAKARTA USING HEAT INDEX (HUMIDEX)

Interactions between human and environment about the influence of the physical atmosphere’s state or weather on human is expressed in com- fort level. The complex relationship between health and weather factors with human comfort is defined as biometeorological index. One of the biometeorological indices is heat index called as Humidex. Studies about Humidex in Jakarta were conducted using climate data stations of Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), namely air temperature, relative humidity and wind speed daily average during 1985 to 2012. The purpose of this study was to determine the level of thermal comfort using heat index Humidex in Jakarta and its climatological trends during 1985 to 2012. Comparative analysis between Humidex and the wind speed and also with the number of vehicles in Jakarta were conducted to determine their impact to the heat index in Jakarta. The results showed that the Humidex monthly average in Jakarta ranged between 36,1 °C and 39,5 °C. Humidex monthly pattern had two peaks with the first peak was on May and the second one was on November, while the lowest value was recorded on August and January. Humidex in Jakarta tended to increase between 0.05 °C and 0.08 °C with its coefficient of determination (R2) was between 0.36 and 0.71. The effect of wind speed to Humidex was lowering the value of Humidex which increased the thermal comfort. Meanwhile, the number of vehicles showed a tendency to grow exponentially, which affected the further decline in thermal comfort level in Jakarta

VISION SYSTEM DEVELOPMENT IN ECCENTRICITY TESTING FOR KWH METER UPPER BEARING

Eccentricity measurement techniques are developed to ensure optimization of operational works, either for large or small objects such as upper bearing kWH meter. Small object eccentricity testing has been done by using precise and sensitive touch trigger probing and a special sofware that makes it expensive. This study developed a more economical vision systemin eccentricity testing. It consists of bearing holder and CCD microscope as an image recorder and computerized image processing. It uses three tested bearing during image recording process, which obtained 12 images from each tested bearing taken from every 30o angle, and one image as registration reference. Image registration process is conducted to correct imperfections bearing mounting into its holder and use centroid method to test the eccentricity of upper bearing kWH meter. This study is succeed in making an eccentricity testing prototype of upper bearing kWH meter which obtained result of 2nd bearing has its largest standard deviation. From all standard deviation value obtained that x -axis (horizontal) standard deviation is larger than y-axis (vertical) which means that detection of x direction is more accurate than y direction. To enhance precision image acquisition in the next study, it is expected the use of a computer system with homogeneous illumination is enabled