Applied Mechanics and Materials Vol. 771

Abstract: Seismic data acquisition needed a relatively fast data logger and multi channels input capability. For this purpose, we construct a measuring instruments based on low cost voltage data logger DI710ULS from DATAQ. The sensors (geophones) have 4.5 [Hz] natural frequency, produce an alternating electric voltage at rate 28 [V/m/s]. The ground shaking / velocity rate of active seismic surface-wave measurement from 5 kg hammer, at 3m distances, is less than 2 [mm/s]. This will produce an alternating voltage at less than 100 [mV].The active seismic surface wave measurements need around 1 ms time sampling for every channels and this instruments can record 7200 data for 8 differential channels, which is sufficient for this purpose. The DI710ULS has a standalone capability and all digital data were recorded in SDcard, whose very light and compact for field acquisition. By only 14[bit] DAC, the data shows reliable and seems good enough by 12.2 [μV] sampling. The data collected by using this data logger were successfully processed for surface wave analysis, and giving a reasonable result.

Abstract: A leak detection system using acoustic emission methods is developed. For this, an experimental rig to detect leak was built using 8” galvanized steel pipe. The length of the pipe is 2 meters. A leak was made with 3 mm diameter and located in 1 meter from the end pipe. The pipe was filled with water and compressed until certain pressure reached. An acoustic emission transducer from Brüel and Kjær type 8313 is mounted on the pipe wall and connected to digital oscilloscope to detect AE signal. The experiment conducted by placing a sensor at a distance of 15 cm, 30 cm, 45 cm, 60 cm, and 75 cm from the position of the leak. Measurements were also performed with the variation of the pressure 3 bar, 4 bars, 5 bars, 6 bars, and 7 bar for those points.Considering acoustic emission wave travelling on pipe is plane wave, leak detection using energy attenuation emission become possible that is different from the method commonly used. Propagation constant is thus required and obtained based on experimental result where the amplitude varies with the spatial and pressure. It is found that for the case considered here. Subsequently, distance of leak location can be determined by the propagation constant and the ratio of energy. Using this method, the error of prediction is about 15.8 %.

Abstract: Water surface level should get special attention as water can cause disasters such as flood when its surface exceeds a certain level. A real time early warning system to monitor water surface level is necessary for avoiding severe effects of flood to human life. A web-based water level measuring system using an ultrasonic sensor can be an alternative choice for developing the early warning system. It is known that the system has advantages in the installation and maintenance compared to other systems. This paper discusses the design of a water level measuring system integrated with an internet web server. Ultrasonic sensors are used to measure the water surface level. A GSM / GPRS-based communication system is applied for sending measured water levels to a web server. The results indicate that the measurement data are in accordance with the water levels manually obtained. The results also show that the system works real time.

Abstract: Currently, battery is very indispensable as a power supply of various electronic devices. Therefore, research on batteries has developed rapidly and their charging-discharging properties must be characterized. This paper reports the development of an electronic system used to characterize batteries. The system consists of a programmable power source (PPS), a programmable load (PL), an amperemeter, a voltmeter, and a computer. The PPS and PL are used interchangeably, one for charging and the other for discharging. A battery under test (BUT) is directly connected to the PPS and PL interchangeably. A 1.2 V NiMH battery with a capacity of 750mAh has been characterized their charging-discharging properties. It has been found that the curves of charge and discharge are in accordance with the theories.

Abstract: Bio-impedance based sensor using organic polymer-membrane was presented in this paper. The Ca-alginate with glycerol as plasticizer used in the experiments was fabricated by slip casting method on a glass substrates. After atmospheric heating treatment of edible films at 60°C for 24 hours, the films-membranes of 50 mm were obtained. Bio-impedance characterizations were carried out by LCR meter at room temperature. The experiment results showed that the sensor finely operated at low frequency i.e. less than 40 kHz. Response of the sensor increased with the increase of samples mass and became constant after a critical mass. Finally, bio-impedance responses of beef and pork were clearly indicated by a different magnitude that it is possible to apply the films-membranes as bio-sensor applications.

Abstract: An unconsolidated undrained (UU) test is one type of triaxial compression tests based on the nature of loading and drainage conditions. In order to imitate the UU triaxial compression tests, a UU triaxial emulator with a graphical user interface (GUI) was developed. It has 5 deformation sensors (4 radial deformations and one vertical deformation) and one axial pressure sensor. In addition, other inputs of the emulator are the cell pressure, the height of sample, and the diameter of sample, which are provided by the user. The emulator also facilitates the analysis and storage of measurement data. Deformation data fed to the emulator were obtained from real measurements [H. Nawir, Viscous effects on yielding characteristics of sand in triaxial compression, Dissertation, Civil Eng. Dept., The University of Tokyo, 2002]. Using the measurement data, the stress vs radial strain, stress vs vertical strain, and Mohr-Coulomb circle curves were obtained and displayed by the emulator.

Abstract: A focused ion beam (FIB) mill equipped with a microsampling (MS) unit and combined with transmission electron microscopy (TEM)/scanning TEM-energy dispersive x-ray spectroscopy (STEM-EDXS) is a powerful tool for studies of the functional advanced materials. For the studies, the specimen must be prepared as a thin foil which is tranparent to the electron beam. Focused ion beam is very effective method for fabricating TEM specimen of the cross-sectional thin film with the “lift-out” technique using a tungsten (W)-needle probe as a micromanipulator. A multilayer film of MgB₂/Ni deposited on a Si (001) substrate prepared by FIB-MS technique is presented. Before FIB fabrication, the surface of the multilayer film was coated with W-film to prevent the surface from bombardment by the ion beam. A bright field (BF)-STEM image of the multilayer film related to two-dimensional (2D) elemental mapping clearly showed the presence of MgB₂-and Ni-nanolayers. The measured experimental spacing between Ni-nanolayers was comparable with the actual specimen design, but the thickness of Ni-nanolayer was not. Unexpected nanostructures of the formation of SiO₂ film on the substrate surface and holes within the film were observed.

Abstract: Corneal Arcus is a circular ring of lipid secretion that is deposited in the periphery of cornea. This ring is normally found in elderly people (a.k.a. arcus senilis) or even in younger ones suffering from metabolic syndrom (a.k.a. arcus juvenilis). Many researchers have confirmed that the ring have diagnostic values, i.e. as predictor for coronary artery diseases and lipid stratification. Efforts to develop flexible, low-cost, but also an accurate acquisition system will be described. The system is constructed from commercially available plastic welding google, equipped with a Logitec C525 webcam and LEDs lighting system powered though USB cable. Steps of calibration procedures were then implemented, in order to produce the equally-magnified as well as calibrated preprocessed images for further accurate quantifying steps.

Abstract: Hemodialysis is one of the treatment methods for the patients with end stage renal disease. It is conducted through the use of artificial kidney or dialyzer, located outside of the human body. During the hemodialysis therapy, small air bubbles may infiltrate through the blood tubing and coalesce to perform the larger bubble which can be harmfull for the patient if entering the patient’s blood circulatory system. The objective of this work is to develop an ultrasonic based air bubble detection system as well as the safety system, mainly the electronic system, for hemodialysis machine application. The safety systems consits an electronic for activating visual and sound alarms, and tube clamp. It is used for preventing the embolism during the hemodialysis therapy. The research method covers the conceptual design, detail design, prototyping and performance testing for both hardware and software. The hardware system consists of air detector module, analog circuitry which consists of transmitter and receiver, digital circuitry with DSP based SOM (system on module) and I/O interface. The software system has two main functions. It is for controlling the hardware and processing the signals digitally. The integration between the hardware and the software making the system be able to detect the presence of air bubble. In addition, the software had possess the capability for triggering a tube clamp as well as activating visual and audio alarms. The tubing clamp was used to stop the fluid flow in the blood tubing and prevent an air bubble from entering the patient circulatory system. The validation test was conducted to verify the functionality of the system. For testing purposes, an experimental flow loop was constructed. This loop consits of peristaltic pump, bubble injector, tube clamp, air flow meter, liquid flow meter, and bubble detector. Several test runs by using simulated blood (Dextran 70 solution) were performed. To test the performance of bubble detection system, comparison between measurement of PWM signals conducted using the DSP and oscilloscope was presented in this work. It shows that error procentage between two types of measurement is less than 5%.

Abstract: Low field and room temperature operation range are two critical requirements for magnetic sensors. In this paper, nanoparticles of La_0.7Sr_0.3MnO₃ (LSMO) were elaborated to fulfill these requirements. La_0.7Sr_0.3MnO₃ nanoparticles were synthesized using sol-gel method. The physical properties of LSMO were examined by X-Ray diffraction and Scanning Electron Microscope. The ferromagnetic nature of LSMO samples was confirmed by magnetization measurements. Nanoparticles were pressed in shape of pellets and sintered at different temperatures of 900°C, 1000°C, 1100°C and 1200°C. Magnetoresistive measurements were taken at room temperature with magnetic field (μH) in range ±110 mT. The experimental results show maximum magnetoresistive ratio and sensitivity of 1.3% and 0.023%/mT respectively for sample sintered at 1000°C. Other sensor characteristics namely hysteresis error, response time and noise measurement were also given.