Journal of Engineering and Technological Sciences
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Assessing Log Reduction Values of Conventional Water Treatment Plants with Microbially Highly Polluted Raw Water Sources
Get PDFBecause of the global outlook of microbial pathogens contributed by river basins that are characterized by highly populated urbanized areas and other activities with poor wastewater management, it is imperative to assess the sufficiency of conventional water treatment plants with microbially highly polluted raw surface water sources in supplying pathogen-free drinking water. By using the log reduction value (LRV), the microbial safety of the drinking water supply from WTP Badaksinga, Bandung City, Indonesia, was assessed, from the raw water sources to the conventional water treatment units. E. coli, total coliform, and Clostridium perfringens (as a surrogate of the Cryptosporidium parvum protozoan) were selected as pathogens. It was found that with E. coli concentrations of > 20,000 MPN/100 ml, all the raw water sources should be categorized as not suitable for drinking water sources. The LRVs of conventional treatment units ranged from 0.67 to 1.4 for all pathogens. For the disinfection unit, the LRVs ranged from 3.0 to 3.71 for E. coli and total coliform, and 0 for Clostridium perfringens. Based on the results, the drinking water from WTP Badaksinga is safe from bacteria contamination but theoretically requires an additional barrier for protozoa safety. The assessment found that the LRVs of pre-sedimentation and combined flocculation-sedimentation units in conventional treatment systems need to be (re)assessed
Differences in Biochar Sources for Controlled Nitrogen Loss in a Hybrid Maize Agroforestry System with Melaleuca cajuputi
Get PDFBiochar is used to improve soil fertility and control nitrogen loss in soil. This study aimed to evaluate the difference between biochar sources, namely Melaleuca cajuputi waste and rice husk, for controlled nitrogen loss in hybrid maize planted between Melaleuca cajuputi stands. A split-plot design with three replications was used. The main plot was composed of biochar sources (BS), i.e., without biochar application (WB), Melaleuca cajuputi biochar (MCB), and rice husk biochar (RHB). The subplot was the urea fertilizer dosage, i.e., 0, 150, 300, and 450 kg/ha. The observation parameters were nitrate reductase activity (NRA), total chlorophyll (TC), leaf photosynthesis rate (LPR), nitrogen loss (NL), nitrogen use efficiency (NUE), and seed yield per hectare (SY). The data were analyzed with ANCOVA and LS-means. The results showed that there was no significant difference between mixing MCB or RHB in UF for all hybrid maize parameters, whereas significant differences were observed with WB. The NL values of MCB and RHB were 13.85 and 13.08 kg/ha N, i.e., NL was significantly reduced by 70.90% and 72.51%, and the percentage of SY increased by 28.60% and 37.94% compared to WB, respectively
Optimal Design of V-Shaped Fin Heat Sink for Active Antenna Unit of 5G Base Station
Get PDFThe active antenna unit (AAU) is one of the main parts of the 5G base station, which has a large size and a high density of chipsets, and operates at a significantly high temperature. This systematic study presents an optimal design for the heat sink of an AAU with a V-shaped fin arrangement. First, a simulation of the heat dissipation was conducted on two designs of the heat sink – in-line and V-shaped fins – which was validated by experimental results. The result shows that the heat sink with V-shaped fins performed better compared to conventional models such as heat sinks with in-line fins. Secondly, computational fluid dynamics (CFD) and the Lagrange interpolation method were applied to find out an optimal set of design parameters for the heat sink. It is worth noting that the optimal parameters of the orientation angle and fin spacing considerably affected the heat sink’s performance.
The Effect of Cyclic Impact Loads on Rock Properties
Get PDFThis study was conducted mainly in the laboratory to evaluate the effect of cyclic impact loads on rock properties. The test sample was a rock-like material made of cement, sand, and water. The sample was given an impact load from a metal pounder that was dropped at various heights. The load was repeatedly applied to the sample until it was damaged and/or until failure. The test results revealed four stages in the fracturing process, starting with cratering of the upper surface of the sample, formation of initial fractures, fracture development along the sample, and finally sample failure. The test results also revealed that with an increase of impact load, the number of cycles until failure decreases. Furthermore, the value of uniaxial compressive strength and Young’s modulus decreases with increasing number of cyclic loads. The decrease is proportional to the increase of the damage value
Brine Evaporation Modeling in WAIV System Using Penman, Priestley-Taylor, and Harbeck Models
Get PDFIndonesia is a maritime country with a vast ocean area. Indonesia has high potential to produce salt because it has a lot of saltwater resources. When sea salt is harvested, seawater evaporates from a concentration of 3.5°Be to 29°Be. Evaporation can be affected by several factors, such as air temperature, wind speed, water vapor pressure, humidity, radiation, geographical location, time interval, and season. Many modifications have been made to increase the evaporation rate in salt production. One of them is the WAIV (Wind-Aided Intensified eVaporation) method. WAIV evaporation systems utilize sunlight and wind to accelerate the evaporation rate. The modeling in this study was adjusted to the environmental conditions in the case study for which it was necessary to determine new parameter values for the existing models. The Penman, Priestley-Taylor, and Harbeck models were used. The Harbeck model has been studied in previous studies, which were used as a reference in the present study. This study first determined and then validated the parameter values obtained. A simulation of the evaporation rate was conducted in a different place, namely Kupang, East Nusa Tenggara, Indonesia using Meteorology, Climatology, and Geophysical Agency (Indonesian: Badan Meteorologi, Klimatologi, dan Geofisika / BMKG) data
Simulation Study on Hypervelocity Penetration of Lab Scaled Shape Charge Mechanism
Get PDFShaped charge (SC) is a mechanism used by defence industries as anti-armored weapon to penetrate armored plates. Numerous studies have been conducted on the shaped charged effects. However, experimental studies are limited due to great safety requirement and limited access to high grade explosive. Due to these limitations, an experimental study on a small-scale shaped charge mechanism (SCM) penetration blast test was conducted against five (5) types of target materials. The experimental data is then verified by simulation to proof that it can be used to predict the SC penetration data. This paper intent to present a comparative study on the effect of shaped charge blast conducted by simulation with the actual experimental results. In order to conduct this study, a 2D AUTODYN software were used to develop the SC blast model against five (5) types of target materials. This study concludes that the 2D AUTODYN simulations results can predict the hypervelocity penetration for all target materials compared to the experimental test with an average difference of 9.1 %
Design of Split-Hopkinson Pressure Bar Specimen Fixture to Accommodate Punch and Double-Notch Shear Testing
Get PDFThis study focused on the design of a specimen fixture which can be installed on the end of a conventional transmission bar so that shear testing (punch and double-notch) can be conducted with any conventional split-Hopkinson apparatus. The research was conducted by using the finite element method in Abaqus/CAE with 6061-T651 Aluminum as the specimen material. The research successfully determined the effect of the fixture’s geometry and dimensions on the split-Hopkinson shear bar testing results. The optimum double-notch fixture provides great accuracy, having only a shear stress value difference of 1.49% with the original setup, while attaining force equilibrium after only 70 μs. The punch fixture, however, could only reach force equilibrium after 100 μs, thus providing too few observable data. Future work on the punch fixture is needed
Influence of the Process Parameters on the Microhardness and the Wear Resistance of Friction Stir Processed H65 Copper Alloy
Get PDFFriction stir processing (FSP) was used to modify a larger-size surface of H65 copper alloy. The influence of the traverse speed and the rotation speed on the microstructure, the microhardness and the wear resistance of the modified surface were analyzed. The wear mechanism of the modified H65 copper alloy was revealed. The results indicate that the grain size was greatly refined after FSP compared with the parent metal and that the grain size increased with the increment of the rotation speed. The average microhardness of the modified surface was higher than that of the parent metal. The average microhardness had a highest value of 174.13 HV when the traverse speed was 200 mm/min and the rotation speed was 200 rpm, i.e., 21% higher than that of the parent metal. The average microhardness decreased with the increase of the rotation speed. When the traverse speed was 200 mm/min and the rotation speed was 600 rpm, the average friction coefficient of the modified surface was the smallest (0.3213), which was lower than that of the parent metal (0.3810). The wear mechanism of the H65 copper alloy modified by FSP was mainly adhesive wear accompanied by local abrasive wear
Design and Development of a Multi-Sided Tabletop Augmented Reality 3D Display Coupled with Remote 3D Imaging Module
Get PDFThis paper proposes a tabletop augmented reality (AR) 3D display paired with a remote 3D image capture setup that can provide three-dimensional AR visualization of remote objects or persons in real-time. The front-side view is presented in stereo-3D format, while the left-side and right-side views are visualized in 2D format. Transparent glass surfaces are used to demonstrate the volumetric 3D augmentation of the captured object. The developed AR display prototype mainly consists of four 40 × 30 cm2 LCD panels, 54% partially reflective glass, an in-house developed housing assembly, and a processing unit. The capture setup consists of four 720p cameras to capture the front-side stereo view and both the left- and right-side views. The real-time remote operation is demonstrated by connecting the display and imaging units through the Internet. Various system characteristics, such as range of viewing angle, stereo crosstalk, polarization perseverance, frame rate, and amount of reflected and transmitted light through partially reflective glass, were examined. The demonstrated system provided 35% optical transparency and less than 4% stereo crosstalk within a viewing angle of ±20 degrees. An average frame rate of 7.5 frames per second was achieved when the resolution per view was 240 × 240 pixels
A Comparative Study of Pt Depositing Methods (Chemical Reduction vs Photo-Assisted Deposition) onto TiO2 Nanoparticles for Hydrogen Photo-Production
Get PDFIn this paper, we report a comparative study on two methods (chemical reduction and photo-assisted deposition) of incorporating Pt onto TiO2 nanoparticles (TNP) for H2 generation. The phase structure of the photocatalysts was scrutinized utilizing TEM and XRD. The degree of dispersion of Pt on the TNP was calculated by a pulse chemisorption technique using TPDRO equipment. The results provided by TEM imagery, EDX spectra, elemental mapping, and AAS confirmed the successful deposition of Pt on TNP. XRD patterns confirmed an anatase and rutile crystallite structure, while UV-Vis spectra showed reduction of the bandgap from a typical value of 3.2 eV to ca. 2.9 eV. It was found that there is a correlation between the deposited Pt and dispersed Pt on the TNP with H2 generation. The chemical reduction method offered a higher degree of Pt deposition, resulting in a 2.75 times larger amount of deposited Pt compared to photodeposition. This feature is perceived to contribute a higher H2 yield (3,283 µmol) at 1 w% of Pt loading