Elfi Yuliza

Enhancement Performance of Dye-Sensitized Solar Cells from Black Rice as Dye and Black Ink as Counter Electrode with Inserting Copper on the Space between TiO2 Particle’s by Using Electroplating Method

In this study, we report well performance of Dye Sensitized Solar Cell (DSSC) coated with copper (Cu) by using the electroplating method. The Cu nanoparticle was impregnated into the pore of the titanium dioxide (TiO2) thin film. Particle contact between Cu and TiO2 plays important role to reduce the recombination effect of the electron and also lead to increase the electron transport in DSSC cell. Here, we used natural dye extracted from black rice and carbon from black ink as counter electrode. It is found that efficiency of DSSC coated with Cu nanoparticle is higher than pure DSSC which is obtained from I-V characterization. It shows that efficiency of DSSC is about 0.019% without coating Cu and enhanced about 0.105% after coating Cu. The analysis of internal resistance of DSSC was measured from Electrochemical Impedance Spectroscopy (EIS) characterization.

Dye-Sensitized Solar Cells (DSSC) from Black Rice and its Performance Improvement by Depositing Interconnected Copper (Copper Bridge) into the Space between TiO2 Nanoparticles

Dye-sensitized solar cell (DSSC) which employed natural dye from black rice has been successfully fabricated and improved its performance by depositing interconnected copper (copper bridge) on the space between TiO2. The copper bridge has significant role in minimizing recombination of electron-hole which occurred in TiO2 surface by trapping electron and facilitating to anode. The presence of interconnected copper nanoparticle in the space between TiO2 nanoparticle was confirmed by Scanning Electron Microscopy (SEM) and X-Ray Diffractometer (XRD). The current-voltage (I-V) characterization of DSSC solar cells by using Keithley 617 was also performed to investigate performance of solar cells under sun illumination in varying intensities. It is found that performance of copper coated DSSC solar cells (efficiency 0.35% and fill factor 0.35) is higher than DSSC without copper coating (efficiency 0.17% and fill factor 0.35). This result is consistent with impedance spectroscopy analyzing where the internal resistance of copper coated DSSC solar cells is lower than DSSC without coated. It is concluded that performance of DSSC increasing with decreasing of internal resistance. Our finding is higher than other researcher reports in Ref. [13] and [14] with similar structure and kind of natural dye. In addition, this paper also reports the use of polymer electrolyte which employing polyvinyl acetate (PVA) containing lithium ion to maintain long-term stability of device.

Potentiometer a simple light dependent resistor-based digital

A digital potentiometer, which can be used to implement automatic calibration procedure in a circuit, to control a switch of a power supply, or as a load tester, was developed by using a light-dependent resistor (LDR) and implementing a proportional controller. It consisted of a light emitting diode (LED) used to change the resistance of LDR, two LDRs set as the output and the feedback of the controller, a keypad to enter the set point, an LCD to present the data and the processes of microcontroller, and an ATmega 8535 microcontroller to manage all processes of the system. Under the trial-error tuning method, it has been obtained that the proportional constant was 500. For the desired resistance ranging from 5 to 10kΩ, its steady-state error was in the range of 20 to 290Ω. In fact, this maximum steady-state error (290Ω) was higher than those obtained from the previous works. However, the developed system was simple and low cost.

Design and implementation of wireless sensor network on Ground movement Detection System

The raise of land usage and human population increase the number of areas which are prone to landslide disaster. Real time monitoring system on these risk areas can minimize the losses caused by it. One physical phenomenon that can be observed from this disaster is ground movements. This paper discusses about the implementation of wireless sensor network for real time ground movement monitoring. The system consists of Inclinometer, GPS, Xbee Pro, SIM900 and a 9 V power supply. To detect the ground movement, the system used inclinometer sensor. The calibration was done using a homemade tilt calibrator. Xbee pro was used as node transmission system with star topology and then SIM900 was used as a transmitter between the coordinator with the server. The system additionally used GPS to show the position of node and to detect the occurrence of landslide at certain area. Code igniter was used to build web server so that the data can be accessed in real time. From the test, it was shown that the system could detect the ground movement and the observation data was sent to the server precisely.

A simple and low cost tilt examiner system development for a precise landslide early warning system

Historical data for every disaster provide the information about every single physical phenomenon that can be observed to estimate and monitor the happening of the next disaster event. Some physical parameter that often be investigated are ground movement and changing inclination of the land. Those phenomena are the key points on predicting the occurrence of disaster especially landslide and volcano eruption. One of the method that can be used to prevent the loss of life caused by the disasters is by observing the movement and the change of the slope of inclination at the prone areas using tilt sensor. The increase of possibility of disaster occurrence is reflected on the increase of tilt sensor usage. Therefore, a simple system for testing the performance of a tilt sensor is required. A simple and low cost tilt calibrator has been made by using a stepper motor that is controlled by AVR ATMega8 in which its data and control parameter would be displayed in a 16×2 LCD. The system calibrator was developed to...

Development of a simple low-scale solar simulator and its light distribution

A simple low-scale solar simulator was developed. Three different lamps, which are conventional lightbulb, softone lightbulb, and halogen lamp, were employed as light sources. The halogen lamp, in fact, gave better intensity compared to the other lamps in which its intensity is closer to the field-measured sun intensity. In addition to measuring the light intensity distribution inside the simulator, simulation was also done using the Monte Carlo method. It was found that the Monte Carlo simulation fit very well the experimental data. Moreover, the light was centralized beneath the light source and well distributed inside the chamber. The intensity along the horizontal plane varied according to its position. The developed system can therefore be used for simulating the real sunlight very well.

Stability of granular tunnel

AbstractWe demonstrated that the stability of tunnels made of granular matter is strongly dependent on the grain size, tunnel diameter, and water content inside the granules. Larger tunnel radius, larger grain size, and too much water content tend to destabilize the tunnel. We also developed a model to describe such findings. We identified a phase diagram of stability which is significantly controlled by the granular bond order. For granular bond order of above unity, we always able to build a stable tunnel. For granular bond order of less than unity, we obtained a general expression for estimating the maximum thickness of the stable tunnel. The phenomena related to granular tunnel stability have occurred in human activities (such as a collapse of the sand hole made on the beach) as well as in living animals (such as burrows dug by crabs, antlions, mongoose, beetles, turtles, or some species of rats). To the best of our knowledge, this work is the first exploration regarding the stability of the granular tunnel.

A simple landslide model at a laboratory scale

Landslide, which is one of the natural disasters that occurs frequently, often causes very adverse effects. Landslide early warning systems, which are installed at prone areas, measure physical parameters closely related to landslides and give warning signals indicating that landslides would occur. To determine the critical values of the measured physical parameters or test the early warning system itself, a laboratory scale model of a rotational landslide was developed. This rotational landslide model had a size of 250×45×40 cm3 and was equipped with soil moisture sensors, accelerometers, and automated measurement system. The soil moisture sensors were used to determine the water content in soil sample. The accelerometers were employed to detect movements in x-, y-, and z-direction. Therefore, the flow and rotational landslides were expected to be modeled and characterized. The developed landslide model could be used to evaluate the effects of slope, soil type, and water seepage on the incidence of lands...

Study of soil moisture sensor for landslide early warning system: Experiment in laboratory scale

The high rate of rainfall is the main trigger factor in many cases of landslides. However, each type of soils has unique characteristics and behavior concerning the rainfall infiltration. Therefore, early warning system of landslide will be more accurate by monitoring the changes of ground water condition. In this study, the monitoring of ground water changes was designed by using soil moisture sensor and simple microcontroller for data processing. The performance of soil moisture sensor was calibrated using the gravimetric method. To determine the soil characteristic and behavior with respect to water content that induce landslides, an experiment involving small-scale landslide model was conducted. From these experiments, the electric resistance of the soil increased as soil water content increases. The increase of soil water content led to the rise of the pore pressure and soil weight which could cause soil vulnerability to the movement. In addition, the various soil types were used to determine the responses of soils that induce the slope failure. Experimental results showed that each type of soils has different volumetric water content, soil matrix suction and shear strength of the slope. This condition influenced the slope stability that trigger of landslide.

Instrumentation system design and laboratory scale simulation of landslide disaster mitigation

Research on landslide has been developed recently because it may endanger human life. Landslide is the movement of rock, detritus, or soils caused by the action of gravity. Landslides are influenced by several factors such as ground slope, degree of rainfall, land cover (ground layers), and the vibration around the slopes. From these factors, tilt detection sensors and soil moisture sensor have been developed to detect landslide failure. These sensors mounted so that it can detect the occurrence of landslides. The study was conducted on a container which contains the sloping ground. Landslide, slope processes, and soil humidity were investigated in this container. MMA8451Q accelerometer was used as a tilt sensor to detect the acceleration assembled in MEMS (Micro Mechanical System) technology since it is easily available, mass- produced, inexpensive, and high-precision output data. Landslide simulator has been developed hence the process leading to landslide event can be directly analyzed without the need of real life occurrence of landslides. The simulator was made from glass with size 80 cm × 20 cm × 40 cm that was filled by soil. Based on the simulation results, there were changes on accelerometer and soil moisture data during the landslide occurrence.