Journal of Engineering and Technological Sciences
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Development of Electrode Deposition Methods for Scale-up of Dye Sensitized Solar Cells
Get PDFThis research studied the effect of electrode deposition method on the performance of dye-sensitized solar cells (DSSCs). Four deposition methods (bar coating, doctor blade coating, screen printing, and spray coating) were compared. For commercial production purposes, applicability of the methods to a scaled-up DSSC was studied. In order to minimize the production cost, commercial activated carbon was utilized as counter electrode. The experimental results showed that the doctor blade technique provided the best DSSC performance among the investigated methods. Based on the study of cell I-V characteristics, the photoelectric conversion efficiency of the DSSC with an electrode active area of 70 cm2 was significantly lower than with 5 cm2 despite using the same deposition method. The electrochemical characteristics of the cells were further studied using electrochemical impedance analysis
Annotation of Using Borehole Time-Lapse Gravity by Genetic Algorithm Inversion for Subsurface Modeling
Get PDFWe present the annotation to a genetic algorithm (GA) method for an inverse synthetic subsurface density model using surface and borehole time-lapse gravity data. The objective of the inversion is to find the boundaries of the object area and background, where one bit of the chromosome represents the densities. The model that was used in this paper was a simple homogeneous body anomaly and a simplified real water mass injection model in order to argue that the code is suitable for field modeling. We show the influences of the existence of borehole gravity data and location towards the inversion, where the result indicates that an additional good borehole location could increase the success rate up to 13.33% compared to without gravity borehole data for the simple model and up to 4.39% for the field model. The inversion produced the best results when the borehole positions were placed in a state of symmetry towards the body object's mass
Investigation of Dy3+ Ion Doped Borate Glasses and Their Potential for WLED and Laser Application
Get PDFIn this research, Dy3+ ion-doped Na2O-PbO-ZnO-Li2O-B2O3 glasses were developed using the melt and quenching method. The addition of Dy3+ ions in the glass improved the optical properties. The XRD graph verified the amorphous of the glass sample. FTIR showed the vibration of BO3 and BO4 in the structure of the glass. The enhancement of NBOs in the structure of the glass affected the reduction of the bandgap energy of the glass. The hypersensitive transition of the present glass was found at 1270 nm (infrared region) due to electron movement from the 6H15/2 level to the 6H9/2+6F11/2 level. The strong white emission of the glasses came from 575 nm (yellow region) and 483 nm (blue region) when excited by 349 nm. The CIE 1931 chromaticity was located at (0.37;0.40) and verified the white emission of the glasses. Meanwhile, the trendline of the JO parameter was W2 > W6 > W4,indicating the high ionic character of the glass structure. The value of the calculated branching ratio and emission cross-section of Dy_1.0 glass was 0.64 and 0.90 x 10-20 cm2, respectively. From the analysis of results, the present glass has high potential for WLED and laser application
Adsorption of Gold from Aqueous Systems Using Microbial Thermophilic Proteins
Get PDFA precious metal such as gold can be obtained from mining. Metals in low concentrations at geothermal sites or in industrial waste are difficult to gain using the conventional mining process. Alternative approaches for recovering metals from dilute solutions have been developed, such as biosorption, i.e. adsorption using microorganisms or their derivatives. In this study, gold in an aqueous system was recovered via biosorption using proteins produced from an isolated thermophilic bacterial strain. Modified Thermus enhanced medium was used as the medium to improve protein production from the thermophilic bacterial strain. The microbial proteins showed effective conditions for Au3+ ion adsorption. The optimum adsorption conditions for Au ions occurred at pH 1 with an adsorption capacity of 482.0 mg/g protein. The metal ion adsorption capacity increased with increasing temperature. The adsorption isotherm was conducted at room temperature, because the Au ions could be well fitted by the Freundlich isotherm equation with qmax at 527.229 mg/g protein
Urban Gardening System for Home Organic Vegetables: LED Artificial Light and Irrigation Control
Get PDFDue to the limited amount of space in urban homes, the trend of indoor gardening is growing as it is the most suitable gardening method in the specified environment; moreover, it provides the possibility of growing organic vegetables at home. This paper presents the design and construction of an urban indoor gardening system for growing organic vegetables, with automated functions. LEDs in the spectra of R (637 nm) B (455 nm) and white (3500 K) were applied as horticultural light and were designed using the horticulture lighting calculation tool. The automated irrigation system was controlled by Arduino-based soil moisture sensors. The urban indoor gardener prototype had a cultivation bed of 0.385 m2. The results showed that the LED panel could emit a photosynthetic photon flux density of around 200 ± 7 µmol m-2s-1 with an R to B ratio of 0.7 ± 0.04, and a photoperiod of 16 h per day. The soil moisture control system is automatic and can regulate the soil moisture to the appropriate percentage for agricultural use, which is 50% to 69%. Consequently, it is able to save water and provide an alternative method for efficient water use. The urban indoor gardening system is compact and can be placed in a small indoor corner. The presented system was able to produce organic green-oak lettuce with a weight of 1272.54 g/crop in a restricted area, providing an ease-of-use experience and requiring very little maintenance
Comparison of Surface Characteristics of Medical-grade 316L Stainless Steel Processed by Sand-blasting, Slag Ball-blasting and Shot-blasting Treatments
Get PDFIn this research, a comparative study was carried out to examine the surface characteristics of medical-grade 316L stainless steel after blasting treatments by using angular silica particles, spherical slag balls and spherical metallic shot. The surface roughness, morphology, elemental composition and microhardness distribution of the stainless steel were determined and the possible mechanisms in the evolution of the surface characteristics of the steel exposed to the blasting treatments were established. The results showed that all the blasting treatments conducted in this research increased the roughness and hardness of the steel surface. In this case, the roughest stainless steel surface was achieved by the slag ball-blasting treatment, but the stainless steel with the hardest surface and the thickest hard subsurface layer was obtained by the shot-blasting treatment. On the basis of the findings in this research it can be concluded that the physical properties and surface morphology of particles or shot used in the blasting treatment are critical parameters in determining the surface characteristics of blasted stainless steel
Aging and Rheological Properties of Latex and Crumb Rubber Modified Bitumen Using Dynamic Shear Rheometer
Get PDFRubberized bitumen technology has been applied for a long time to enhance the performance of the asphalt pavement. In this research, the influence of natural rubber (NR) latex and crumb rubber (CR) on the conventional and rheological characteristics of 80/100 penetration grade bitumen before and after aging was compared. Conventional tests of penetration, ring and ball temperature, and ductility were conducted to evaluate the consistency of base bitumen and rubberized bitumen. A dynamic shear rheometer (DSR) test was carried out to evaluate the viscoelastic characteristics of the base and rubberized bitumen. The results showed that the addition of NR latex and CR reduced the penetration grade and increased the ring and ball temperature and ductility of the rubberized bitumen. This indicates that promising enhancement of the bitumen properties can be expected with the addition of NR latex and CR. The rheological properties analysis results showed that addition of CR up to 8% and NR latex up to 4% improved the complex modulus and rutting resistance of the rubberized bitumen compared to conventional bitumen. This indicates that the application of NR latex and CR in bitumen modification is expected to improve the durability of asphalt pavement.
Strength and Deformation Characteristics of Reconstituted Sand under Different Stress Paths in True Triaxial Tests
Get PDFTo improve the geotechnical stress"“strain analysis, the stress"“strain behavior of geomaterial under general three-dimensional stress conditions prevailing in the field need to be captured. The true triaxial apparatus is an enhanced version of the conventional triaxial apparatus, which allows to simulate stresses by applying loadings independently in 3 orthogonal directions. This study evaluated the strength and deformation behavior of Bangka sand under true triaxial test conditions. The test specimens were prepared by means of the multi-sieve sand pluviation method. Various true triaxial test stress paths were applied under axial compression, lateral extension, axial extension, and lateral compression with the objective of understanding and developing the empirical correlation of coarse-grained soil strength parameters in axial compression stress paths related to other stress paths. The test results showed that an increase in the value of b, the parameter used to quantify the relative magnitude of the intermediate principal stress to the other principal stresses, resulted in an increase of the internal friction angle and a decrease of the peak stress ratio. In addition it was observed that the Lade-Duncan failure criterion fitted the results of this study better than other failure criteria, namely the extended von Mises, Mohr-Coulomb, and Matsuoka-Nakai failure criteria
Phytoremediation of Mercury Contaminated Soil with the Addition of Compost
Get PDFPhytoremediation is an alternative technology for processing mercury (Hg) contaminated soil. The objective of this study was to treat Hg contaminated soil by adding compost using Sansevieria trifasciata and Celosia plumosa. The variations of the composition of the growth media were 100% contaminated soil and 80% contaminated soil with 20% compost. The plants used were aged 1 month and 30 cm high. The reactor was a polybag with a diameter and height of 25 cm. Sampling was conducted once every 7 days for 28 days. This research showed that the reactor with growth media consisting of 80% contaminated soil and 20% compost with Sansevieria trifasciata and Celosia plumosa had an Hg removal efficiency of 75.63% (58 mg/kg) and 66.81% (79 mg/kg), respectively. The Hg removal efficiency with growth media consisting of 100% contaminated soil was 74.79% (60 mg/kg) and 65.55% (82 mg/kg) in the reactor with Sansevieria trifasciata and Celosia plumosa respectively
Creep and Electrochemical Corrosion Behavior of Heat-treated Mg-9Al-1Zn Alloy
Get PDFThe high-strength Mg-9Al-1Zn alloy has been extensively investigated due to its potential application as a structural material in the automotive industry. The main challenges for its use are the low creep and corrosion resistance. In this work, heat treatment at 415 °C for 2 h was conducted on as-cast Mg-9Al-1Zn to improve its creep resistance. The corrosion behavior of the alloy was studied by the electrochemical method in an NaCl solution. The creep test results under 66.5 MPa load at 200 °C indicated one order of magnitude higher creep resistance of the heat-treated alloy relative to the as-cast one. The heat-treated specimen was ruptured after 6.5 h while the as-cast one was ruptured within 0.6 h. Creep occurred locally following the β phase in the alloy as evident from the cavities observed after the test. Reduction in the density of the discontinuous β precipitates resulting from heat treatment of the alloy lowered the susceptibility to creep. The smaller volume fraction of β precipitates suppressed the cathodic reaction during the polarization test and raised the electrochemical impedance spectra during the EIS test. The heat treatment improved not only the creep resistance but also the corrosion resistance of the Mg-9Al-1Zn alloy