Demi Soetraprawata

EEG-SSVEP signals extraction with nonlinear adaptive filter for brain-controlled wheelchair

In this paper, an application of nonlinear adaptive filter on EEG-SSVEP extraction for brain-controlled wheelchair is proposed. In the experiment, four subjects with age about 25±1 years were tested. The experimental results in this work show that the implementation of the proposed method achieves a very significant statistical improvement in extracting peak amplitude features. After a short time of practice, most participants could learn to extract the EEG-SSVEP wave with greater than 95% accuracy.

The Structural Design of Six - Axis Force/Torque Sensor Using Virtual Prototyping Technique

The design of a six - axis F/T sensor is an important and challenging research to produce a sensor that is able to measure simultaneously the six - component force and torque accurately and efficiently. The structural design is one of the key issues to be considered to improve the performances of the sensor that cross coupling is the most important factor regarding a sensor quality. The purpose of this study is to design a six - axis F/T sensor that has a novel and compact design, has a low coupling error and can meet the design criteria such as mechanical strength, stiffness, and reliability in the receiving load. Virtual prototyping technique is applied with the aim to shorten the time and reduce the manufactu ring cost of the physical prototypes. In this study, the six - axis F/T sensor is designed using four cross beam symmetrically that is able to measure three axial forces ( , , ) and three axial moments ( , , ) . Based on the structural i ntegrity evaluation, the structure of the sensor will certainly secure to the plastic failure of materials because it is still in the area of the material elasticity. Then based on the simulation results of the strain, th e highest cross - coupling errors i s - 1.67% which is relatively small compared to the principal coupling error. Therefore, the design of six - axis F/T sensor using virtual prototyping

Multi-objective optimization of the structural design of double end beam load cell

Multi-objective optimization of the structural design of double end beam load cell had been performed using a genetic algorithm. Two design variables were used to minimize the structural mass, to maximize the structural strength, and to maximize the level of measurement accuracy. Based on the optimal results, the weight reduction of the structure was successfully achieved of about 8.6%. The design safety factor reached 24 % larger than the yield failure criterion. Therefore, the structure will certainly secure against the plastic deformation. The accuracy of measurement of the load cell was predicted to reach the category of high accuracy due to the amount of strain on the strain gauge cavity managed to exceed ± 1600 με.

Extraction of mental task in recorded EEG signal using ICA-JADE algorithm

An instrument that has special function to record electrical brain activity in scalp is electroencephalograph (EEG). Recently has various function, one of them is brain computer interface (BCI). BCI application can make human brain interaction with environment without other parts of body. Mental task is the important part in BCI system. Mental task which generate from brain, especially happen in central lobe. In fact, mental task disturbed by other signal which generate from other parts of brain. It is make problem to extract the real mental task from brain. In this research algorithm ICA-JADEis used to extract mental task activity in EEG signal recorded. The experiment was collected in 6 subject people. Stimulus for each subjectto move right hand for generate mental task have been design. Result of this research show ICA-JADE method can extract mental task from EEG signal recorded and the quantity perform of ICA-JADE is compared with the pure mental task signal.

Remaining Life Assessment of the Generator Stator Insulation: A Case Study on Suralaya Coal Fired Power Plant in Indonesia

The failure of large generators in generating stations and industrial plants is mainly caused by the failure of the stator winding insulation. The combination of electrical, mechanical and thermal stresses that are accumulated by the number of start-stop times and operating hours can reduce the residual dielectric voltage as the main cause of the deterioration on the insulation. In this study, the remaining life assessment of the generator stator insulation was conducted based on the functional relationship between stresses and remaining dielectric voltage in the worst and average cases. The case study was conducted on the fourth of generator unit in SURALAYA Coal Fired Power Plant in Indonesia that had the service life of over 25 years. To validate the assessment results, partial discharges (PD) test was performed on the stator coils of the generator. Based on the results of evaluation, it was found that the remaining life of the fourth of generator insulation at the worst case had been come to end. For the average case, the remaining life of insulation for Unit 1 and Unit 2 was 12 year, while for Unit 3 and 4 was 17 year. Then from the validation results using the PD test, there was an evidence of the discharging of voids or delamination within the insulation, where the internal discharging was seen to be the most dominant factor from the discharge pattern. However, the PD magnitudes were still within reasonable limits, where the magnitude of the maximum discharge was 3,500 pC for the U phase, while in the V and W phase was 7000 pC, hence it was not categorized as an anomaly.

Fitness for Service Assessment of High Pressure Heater Tube at Coal Fired Power Plant

The structural integrity of heat exchanger tube at high pressure heater of coal-fired power plant has been evaluated using fitness for service (FFS) assessment level 2 and 3. The purpose of this study isto determine the root cause of failure and the remaining life of components thereforethe possibility of failure due to improper design and operation can be known and it become a reference fordesigning a new design tubein a retubing process. Based on the evaluation results using level 2 assessment, the failureon the heat exchanger tubesisnotcaused bythe material creep becausethe total damage due to creep has been successfully met the requirements with the operating life3.873x109hours. However, base on the results of level 3 assessment using finite element, the minimum safety factor against yielding is below 1.0 and itdoesn’t meet the plastic collapse criterion, therefore the possibility of leakage failure on the tube is caused by the improper design which the construction of the tube is not able to withstand the operating load.