Journal of Engineering and Technological Sciences
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The Effect of Linear Low-Density Polyethylene and Palm Kernel Shell Ash Mixture on the Physical, Mechanical and Degradation Properties of Paving Blocks
Get PDFThe aim of this research was to evaluate the physical-mechanical parameters of paving stones obtained on the basis of the mixture of linear low-density polyethylene (LLDPE) and palm kernel shell ash (PKSA) waste. The ratio of LLDPE to PKSA waste (% weight) was varied in five treatments: A0 (100:0), A1 (97.5:2.5), A2 (95:5), A3 (92.5:7.5), A4 (90:10) and A5 (87.5:12.5). The physical appearance, thickness, compressive strength, water absorption, and morphological characteristics of the paving blocks were observed. The blocks were observed at ambient temperature, exposed to sunlight, and placed on the ground surface on day 0 and day 365. The results showed that addition of PKSA waste decreased the compressive strength but increased the water absorption capacity without a significant effect on the thickness of the paving blocks. Observation after 365 days showed insignificant decreases of compressive strength and thickness, whereas the water absorption capacity increased slightly. Small cracks and more voids in the surface, and more brittleness were observed. To summarize, composites of LLDPE and PSKA as filler have physical-mechanical properties that can be used for road pavement blocks
Low-voltage Low-power Bulk-driven CMOS Op-Amp Using Negative Miller Compensation for ECG
Get PDFTwo bulk-driven CMOS (Complementary Metal Oxide Semiconductor) operational amplifier (op-amp) designs for electrocardiogram (ECG) application are presented and compared in this paper. Both op-amps are based on two-stage amplification, where bulk-driven differential input is the first stage, while additional DC gain is the second stage. Different compensation techniques were integrated in each op-amp design. Standard Miller compensation was used for the first op-amp parallel with the second stage. The novelty of the second op-amp is that it utilizes negative Miller compensation between the bulk-driven input node and the output node of the first stag, while standard Miller compensation was used in the second stage. The purpose of this work was to compare DC gain, phase margin (PM) and unit gain frequency (UGF) obtained through different simulated compensation strategies and test results. The op-amps were simulated using 0.25 μm CMOS technology. The simulation results are presented using the standard model libraries from Tanner EDA tools, operating on a single rail +0.8V power supply
Modeling Salinity Propagation in Cikarang Bekasi Laut Channel, Bekasi Regency, West Java Province, Indonesia
Get PDFAn inland waterway will be constructed in an existing channel in West Java, Indonesia. The change of salinity in a river due to capital dredging is investigated using a finite element modeling system. The location of the research is the Cikarang Bekasi Laut (CBL) channel, Bekasi Regency, West Java, Indonesia. The aim of this study is to simulate salinity propagation in the CBL before and after capital dredging. Salinity modeling is carried out using the Surface-water Modeling System (SMS). Field surveys of the topography, bathymetry, currents and water level are conducted for the model. The model results are validated with the current and water level field measurements. The field and model results agree well. The current and salinity results show that the trends are correlated with river discharges. After the capital dredging, the salinity in the CBL increases. Mitigation is carried out by constructing a check dam, which can reduce the average salinity in the upstream region by up to 0.05 ppt during the wet season and up to 0.12 ppt during the dry season
Impact of Al on ZnO Electron Transport Layer in Perovskite Solar Cells
Get PDFPerovskite solar cells have shown remarkable performance and improvements in terms of solar cell efficiency. The ETL material is one of the important components in perovskite solar cells in conducting electrons to produce current. Here, ZnO was used as ETL material in a perovskite solar cell using the SCAPS 1D simulation software. The ZnO ETL showed poor cell efficiency due to its reaction with the perovskite material. A small amount of Al doped into ZnO was introduced to enhance the physiochemical properties of the ZnO against perovskite materials. Al concentrations were varied between 1 and 4 mol% to observe the effect on cell efficiency. Compared with a conventional ZnO ETL solar cell with 0 mol% Al perovskite, the Al-doped based solar cell showed better performance. Meanwhile, perovskite solar cells with 1 mol% Al-doping and appropriate layer thickness showed the best cell performance in improving the charge transport mechanism, resulting in increased cell efficiency. Thus, the parameters studied can be a guide in the fabrication process
Comparative Analysis of Compression Molded Products of Recycled Waste Poly(Vinyl Chloride) and Virgin Poly(Vinyl Chloride) Fill Material
Get PDFWaste poly(vinyl chloride) fill material from the cooling tower of a power plant was used for mechanical recycling. Mechanical recycling is the processing of plastic waste without changing the original chemical structure of the plastic. The waste rigid poly(vinyl chloride) fill material was cleaned, grinded and compression molded at optimized conditions of time, temperature and pressure using a compression molding machine. Virgin poly(vinyl chloride) was purchased and compression molded by the same compression molding machine. The compression molded sheets of waste poly(vinyl chloride) and virgin poly(vinyl chloride) were characterized by attenuated total reflection Fourier transform infrared analyses, tensile properties analyses, and thermal properties analyses. The results revealed that waste rigid poly(vinyl chloride) fill material is mechanically recyclable into new products such as pipes, profiles, furniture and other related products
Experimental Investigation on the Effectiveness of Truss-Shaped Punching Shear Reinforcement in Flat Slab
Get PDFThe use of reinforced concrete flat slabs in building construction increases the floor-to-floor clearance, expedites site operations, and offers aesthetically rewarding features. However, punching shear failure in a flat slab is brittle in nature and can be potentially catastrophic. Many studies have been conducted to improve the punching shear capacity of flat slabs but some of the proposed punching shear reinforcements were complicated and costly. This research aimed to evaluate the effectiveness of a simple and cost-effective; truss-shaped punching shear reinforcement embedded in a 1200 mm × 1200 mm × 175 mm thick flat slab specimen. Three types of truss-shaped punching shear reinforcements were prepared. All specimens were supported at the edges and subjected to gravity load tests. The results showed that the introduction of truss-shaped punching shear reinforcement increased the punching shear capacity in the range of 7.71% to 21.47%. The maximum deflection of these specimens exhibited an insignificant increase compared to the control specimen, suggesting that punching failure governed the ultimate behavior. The additional strength offered by truss-shaped punching shear reinforcement makes flat slabs as a construction material more appealing because they allow them to withstand higher design loads
Isothermal Oxidation Behavior of Ferritic Oxide Dispersion Strengthened Alloy at High Temperatures
Get PDFThis paper discusses the oxidation behaviors of ODS steel alloy of Fe-16Cr-4Al-1Ni-0.4ZrO2 at 700 ℃, 800 ℃, and 900 ℃. X-ray diffraction (XRD) as well as X-ray mapping in a scanning electron microscope were used to characterize the oxidation behavior of the samples. The rate of oxidation was measured based on the thickness of the oxide formed on the surface of the samples. Six types of oxides were identified in all ODS Fe-16Cr-4Al-1Ni-0.4ZrO2 alloy samples after the oxidation tests, dominated by Fe2O3, Fe3O4, Cr2FeO4, AlFeO3, Al2FeO4, and AlFe2O4. The oxidation kinetics of ODS Fe-16Cr-4Al-1Ni-0.4ZrO2 steel at 700, 800, and 900 ℃ followed logarithmic oxidation rate behavior