Estimation of Raindrop Size Distribution Parameters Using Lightning Data over West Sumatra

In situ observations of raindrop size distributions (DSDs) are still limited, especially in the tropics. Therefore, this study develops an alternative method to calculate DSD parameters by utilizing lightning data from the World-Wide Lightning Location Network (WWLLN) observation. DSD data was obtained from Parsivel's observations in the equatorial regions of Indonesia, i.e., Kototabang (100.32◦E, 0.20◦S, 865 m above mean sea level/ASL), Padang (100.46°E, 0.915°S, 200 m ASL), and Sicincin (100.30°E, 0.546°S, 134 m ASL). A gamma distribution parameterized the DSD. Three analysis domains were examined, with a grid of 0.1° x 0.1°, 0.5° x 0.5°, and 1° x 1°. We examined the possibility to calculate the near-instantaneous DSD parameter, so three short time intervals, namely, one, five and ten minutes, were used. The results showed that the number of lightning strokes does not adequately correlate with DSD parameters. This is observed in all time intervals and analysis domains. Thus, the use of lightning data to calculate DSD parameters is not possible for short time interval of DSD (near instantaneous DSD). However, lightning data can estimate the average DSD parameters for an average time of more than one hour, as recommended by previous studies.

Effect of Citric Acid on Electrochemical Properties of Liquid Electrolytes

Effect of citric acid as plasticizer on the electrochemical properties of liquid electrolyte has been studied. Liquid electrolyte was prepared by dissolving citric acid in 1% acetic acid with presence of lithium nitrate salt. Liquid electrolyte is characterized using a conductivity meter to measure the ionic conductivity value. Computer simulation of Density Functional Theory (DFT) with B3LYP/6-31G ++ (d, p) basic set was performed to identify the dominant functional group of citric acid when interact with lithium salt. Increasing the weight of citric acid has increased the ionic conductivity up to 44.89 mS/cm with an optimum weight of 4 g, while the ionic conductivity increases up to 43.00 mS/cm when the percentage of lithium nitrate salt increases up to 30%. The ionic conductivity increases as the salt percentage increases due the interaction between salt and functional group of citric acid. Based on computer simulation of DFT, the dominant functional group in citric acid that interact with lithium salt are carboxylic acid group which is located in the middle of the citric acid chain causing lithium ions to be more likely interact with citric acid.

Effect of Monosaccharides and Disaccharides Type on Ionic Conductivity of Liquid Electrolyte Based Lithium Iodide

Liquid electrolyte was prepared by dissolving glucose, fructose, sucrose and lactose separately with different percentage of lithium iodide (10 – 35%) in aqueous solution of 1% acetic acid. Liquid electrolyte is characterized using conductivity meter to determine ionic conductivity. Computer simulations of Density Functional Theory (DFT) was used to identify the dominant functional groups on monomers such as glucose, sucrose, fructose and lactose when interact with the lithium salt by using B3LYP/6-31G ++ (d, p) basis set. The highest ionic conductivity for monosaccharide is glucose at 28.20 mS/cm while for disaccharide is lactose at 28.00 mS/cm with percentage of salt at 35 wt.%. Ionic conductivity increases when concentration of salt increase because there is an interaction between salt with functional groups of compounds. Based on computer simulations of DFT, interaction between lithium with compounds can be occurred due to negative electrostatic potential on the molecule. Electronegativity value of oxygen atom in glucose (-0.562e) and lactose (-0.567e) higher than fructose (-0.559e) and sucrose (-0.515e). Functional groups that are dominant to interact when interact with lithium salt are O-15 for glucose and O-17 for lactose due to the shorter bond length, the stronger energy attraction between functional groups with lithium.

Characterization of (Mg1.0Zn0.0)TiO3+4 wt%Bi2O3 Ceramics for Application as Resonator in Dielectric Resonator Oscillator Circuit

MgTiO3-based ceramics have potential applications in telecommunications systems at microwave frequencies, such as resonators in dielectric resonator oscillator (DRO) circuits. This paper reports the results of (Mg1.0Zn0.0)TiO3+4wt% Bi2O3 (abbreviated MZT0+4wt%Bi2O3) ceramic fabrication to assess its potential to be used as a resonator in the DRO circuit. We characterized its structure, microstructure, and bulk density. The addition of 4wt%Bi2O3 to MZT0 crystalline powder was carried out via ball-mill. The milled powder was compacted using a die press to obtain pellets. All pellets were sintered at 1100ºC for 4, 6, and 8 h. Ceramic structures of the 4 and 6 h holding time consists of MgTiO3 phase (94.33±2.68) and (95.34±1.95)% molar respectively, while the rest phase was TiO2. The 8-h ceramic structure comprises (96.11±2.94) % molar MgTiO3 accompanied by Mg2TiO5 and TiO2. The ceramics' microstructure consists of a cluster of grains with an average diameter of 1.32-2.24 μm and pores. Bulk density decreases with the increase of sintering holding time. The DRO characterization records a resonance signal each at 5.207, 5.005, and 5.121GHz with power approaching 0 dBm, suggesting that the MZT0+4wt%Bi2O3 ceramics can be used as a resonator in the DRO circuit working in microwave frequencies, especially at 5.0-5.2GHz.

Long-Term Change in Characteristics of Cloud Vertical Structures Over Sumatra from Radiosonde Observations

Study on the vertical structure of cloud in Indonesia in terms of climate change is still very limited. We investigated the long-term change in characteristics of cloud vertical structures over Sumatra from three radiosonde observation stations in this work. The cloud base height (CBH), cloud top height (CT), and the number of cloud layers were retrieved using relative humidity (RH) profiles from radiosonde observation. The height of the cloud base is determined by taking the height of the layer with relative humidity (RH) value > 84% with at least a 3% jump in the RH from the ground level. Sumatra’s most frequently observed cloud layer is a one-layer cloud with an average occurrence rate of > 60%, which is slightly larger than the one-layer cloud globally. The percentage of appearance values at the Padang station, Pangkal Pinang, and Medan are 63.58%, 69.50% and 66.05%. The appearance of low-level clouds also dominates in Sumatra compared to other cloud types. CT and CBH increase with the number of years including all seasons. This is in line with the increase in temperature in Indonesia reported by previous researchers. On the other hand, the clouds’ thickness, especially for the cloud with one layer, varies from one location to another. The thickness of clouds decreases at Padang station and does not change at Pangkal Pinang and Medan stations.

Determination of Climate Factors in Flood and Drought Disaster in Indonesia using Instrumental Variable (IV) Methods

Located in the Southeast Asia region, Indonesia has rainy and dry seasons. In the rainy and dry seasons that occur in Indonesia, often causes many problems in various business sectors and community activities, including floods and droughts. It is known that the disaster will have an impact on material and non-material losses. This study uses climate data and disaster data at the village level to determine the effect of rainfall on disasters. This study uses the instrumental variable method because the model has endogeneity problems. The study results concluded that increased rainfall had a positive impact on flood disasters with a coefficient of 0.003038. Simultaneously, rainfall also impacted drought with a coefficient of -0.000377. Variables in the regression model that are formed can explain 1.74 percent of the flood disaster and 0.59 percent of the drought disaster. These results indicate that most of the other variables can influence flooding and drought. Through this research, it is known that rainfall for floods and droughts is quite significant. Therefore, government and community efforts are needed to anticipate similar disasters.

Application of Complementary Split Ring Resonator for Hyperthermia

One of the most promising research for cancer therapy with less side effects is hyperthermia treatment using metamaterial. This treatment may stand independently or adjunct to other cancer treatments such as chemotherapy, radiotherapy, and others. Metamaterial may control the heating process needed and also the depth of metamaterial itself from the skin surface. In this simulation, complementary split-ring resonator (cSRR) metamaterial with gaps from 0.5 to 3.5 mm can be used for the hyperthermia treatment. In the simulation of the cSRR metamaterial as hyperthermia therapy for cancer cells, the heat generated from each cSRR model was not significantly different. All cSRR models can reach hyperthermal temperatures under 5 minutes. The highest temperature achievement after 60 minutes can be seen in the use of single gap cSRR (58.9 ℃), dual gaps cSRR (58.1 oC), triple gaps cSRR (57.5 ℃), and quad gaps cSRR (57.2 ℃). The cSRR metamaterial structure can be used for hyperthermia therapy by adjusting the treatment duration treatment on cancer cells.

Differences in Mechanisms of Orographic Rainfall over West Sumatra (Case Study: 10 April and 23 April 2004)

Two different mechanisms of orographic rainfall enhancement in West Sumatra were investigated utilizing observed data during the Coupling Processes in the Equatorial Atmosphere (CPEA)-I campaign. The variation of the atmospheric conditions during the campaign was shown by rainfall, surface wind, humidity, and stability index. An X-band Doppler radar captured the atmospheric conditions related to the enhancement of orographic rainfall mechanisms. The dry and less stable atmospheric conditions resulted in the convective type of rainfall. In contrast, the humid and stable atmospheric conditions brought the large-scale rainfall in the mountainous region where the events took place coincided with the inactive and active MJO phases..

Identification of Sand Mineral Content at Beach Tourist Attractions in Sampang Regency through X-Ray Fluorescence and X-Ray Diffraction Testing

Research on the natural mineral content in Sampang Regency has been conducted, namely Camplong Beach, Nepa Beach, and Mandangin Island. The XRF results show that the silica mineral content in Camplong sand at a depth of 0.5 m, 1 m, and 1.5 m are 54.6%, 53.2%, and 57.0%, respectively. Nepa sand shows the highest mineral content is calcium. The calcium content at a depth of 0.5 m, 1 m, and 1.5 m are 51.7%, 58.3%, and 63.0%, respectively. Mandangin Island sand shows the highest calcium content that are 94.69%, 94.65%, and 94.98%, at a depth of 0.5 m, 1 m, and 1.5 m, respectively. XRD test results show that in Camplong sand at a depth of 0.5 m, 1 m, and 1.5 m, SiO2 phase < 94% is formed. In Nepa sand at a depth of 0.5 m, 1 m, and 1.5 m, the SiO2 phase < 80% is formed. For Mandangin Island beach sand with a depth of 0.5 m, 1 m, and 1.5 m, the CaCO3 phase > 90% is formed. This study's results can determine the mineral content of sand, which can be used as a high-tech material to minimize illegal mining.

Prototype of Rainfall Intensity Measurement Using CCD TSL1401CL Linear Sensor Array

A prototype measurement of rainfall intensity was developed using a CCD TSL1401CL linear sensor array. The prototype consists of a He-Ne laser that functions as a light source, which later is focused by the beam expander and conditioned by a convex lens. Each pixel will receive the same voltage depending on the light intensity so that it produces a decimal value of ADC. This ADC decimal value determines rainfall intensity based on the diameter and velocity of the raindrops. The diameter variations used ranges from 1 mm to 10 mm, while for variations in the height of rainfall are 50 cm, 100 cm, and 150 cm. The test results proved that the greater the decimal value of the ADC is, the smaller the diameter of the raindrops detected will be, and vice versa. The values of the diameter and velocity of were used to obtain the value of rainfall intensity. The percentage value of error measuring rainfall intensity is 3.11% when compared to the rain gauge module is still considered rather accurate. However, direct testing is still needed when rain falls with various types and intensities.