An integrated magnetotelluric (MT) and geochemical study of the Blawan geothermal field has been performed. The character of the hot springs, the reservoir temperature, and geothermal reserve potential of Blawan geothermal field are assessed. MT measurements, with 250 m up to 1200 m spacings, were made at 19 sites, and 6 locations at the Blawan hot springs have been sampled for geochemical survey. The results of 2D modelling indicated that the geothermal system in the research area consisted of a cap rock zone (≤32 Ω•m), reservoir zone (>32 – ≤512 Ω•m), and heat source zone (>512 Ω•m), and also identified faults. The characteristics of the hot spring water were identified through analyzing the major and minor elements. A ternary diagram (Cl-SO4-HCO3) showed that the Blawan hot springs consist of bicarbonate water (at locations of AP-01, AP-02, AP-03) and chloride water (at locations of AP-04, AP-05, and AP-06), with a reservoir temperature of approximately 90 °C based on the Na–K–Ca geothermometer results. An estimate of the geothermal energy using the volumetric method, gave a total geothermal reserve potential of 1.823 MWe.

Bioelectric impedance spectroscopy (BIS) has been widely used to study the electrical properties of biological tissue based on the characteristics of the complex electrical impedance dispersions. One of the problems in using the BIS method is the length of time required for the data acquisition process and possibly data analysis as well. In this research, a compact and work rapidly BIS instrumentation system has been developed at a low cost. It is designed to work in the frequency range of 100 Hz to 100 kHz, which is generally used in the fields of biophysics and medical physics. The BIS instrumentation system is built using several integrated modules. The modules are an AC current source to produce a selectable injection current; a data acquisition system to measure voltage, current, and phase difference rapidly and simultaneously; and software to calculate and display measurement results in the form of Bode and Nyquist plots in real time. The developed BIS system has been validated using a simple RC circuit as the sample being tested. The average time needed in the process of data acquisition and analysis until the formation of impedance dispersion curves in the form of Bode and Nyquist plots, for 54 sample frequencies, is less than one minute. The system is able to identify R and C values of the sample with a maximum error of 1.5%. In addition, some simple application examples are also presented in this paper.

Application of Single MEMS-accelerometer to Measure 3-axis Vibrations and 2-axis Tilt-Angle Simultaneously

A simple and low-cost instrumentation system in this research for Electrical Impedance Tomography (EIT) experiments has been developed and committed to educational purposes. The developed EIT system mainly consist of two parts, e.g. chamber or phantom for placing measured sample and electronics device as measuring and controlling system. In the surface of phantom are placed as much as 16-electrodes circularly, the function is to inject current and measure spatial voltage across the object. AC current of 50 kHz is injected to the phantom boundary, then the surface potentials are measured using neighboring method. The developed data acquisition system has ability to record 16 channels simultaneously, thus does not require multiplexing technique which is can lead the delays that impact to the case of errors on the measurement results. For image reconstruction, an open source software, EIDORS, was used. Finite element modelling is a method used to simulate the reconstruction of the image process by imaging spheroidal phantoms in the circular of 16-electrodes array. As a comparison on the image reconstruction results, measurement data is presented in graphical using a Boundary Data Simulation (BDS). The experiment result shows the reconstructed images of a conductor and isolator, presenting the first step towards impedance imaging of other material sample.

Micro Electro Mechanical System (MEMS) accelerometer is commonly used as acceleration-based vibration sensor. The MEMS accelerometer is small device, simple in the implementation design, and relatively inexpensive. But in some fields of application, due to low frequency operation and also small magnitude of the measured signal, for example in seismology, velocity-based vibration sensor is usually more desirable than acceleration-based sensor. In this research, a velocity-based vibration sensor has been developed using MEMS Accelerometer device e.g. MMA7361L. The acceleration-based vibration signal from the MMA7361L is converted into a velocity-based vibration signal by using an integrator circuit module. This module is assembled by using a band-pass filter and an integral-amplifier. The laboratory test shows that the developed sensor system could detect both low and high-frequency vibration signals in velocity-based with good result. The sensor system has a frequency range of 0.02Hz to 148Hz. It is wider frequency than the geophone (seismic sensor), thus the velocity-based MEMS sensor system has capability for geophone replacement.