Maximum Likelihood Channel Estimation for Space Time Block Code - Orthogonal Frequency Division Multiplexing
Nguyen Le Thai, Nguyen Vu Anh Duy
Page Numbers : 320-325
DOI : 10.36348/sjet.2021.v06i09.004
Multiple Input Multiple Output -Orthogonal Frequency Division Multiplexing (MIMO-OFDM) is a promising technique for broad - band communication over mobile wireless channels. This paper presents channel estimation methods for Space Time Block Code - Orthogonal Frequency Division Multiplexing (STBC-OFDM) system. Expectation – Maximization based on an iterative algorithm and Decoupled Maximum Likelihood method are used to reduce computational complexity without loss of estimation accuracy. Simulation results show that the effectiveness of the Decoupled Maximum Likelihood method is improved.
Sept. 24, 2021
Optimization of Cutting Parameters of Tool Wear in Turning Operations: A Review
A. Adamu, M. A. Bawa, A. M. Abioye
Page Numbers : 315-319
DOI : 10.36348/sjet.2021.v06i09.003
Tool wear is one of the major factors that contribute to surface quality, productivity and accuracy in machining. It also determines production flow by increasing the number of shutdowns for tools reshaping. Tool wear is related to cutting process parameters (depth of cut, spindle speed and feed rate), the surface nature of the metal (scaly or smooth), the cutting forces and thermal condition at cutting zone. This paper present review of various works on optimizing the tool wear rate during turning operation. Also, it presents techniques used in monitoring the processes and methods of determining the rate of tool wear with their results in an orthogonal machining operation on different type of materials.
Sept. 24, 2021
Recent Advances and Potential Role of Novel Nanoparticles for Wastewater Treatment with Emphasize Advanced Techniques
Aamir Shehzad, Shamsa Maqsood, Anila Khan, Momil Momil, Muhammad Mujahid Iqbal, Farooq Ahmad, Abdul Noman Razzaq, Muhammad Nasir Akram
Page Numbers : 310-314
DOI : 10.36348/sjet.2021.v06i09.002
Specific nanoparticles are designed in order to deliver the different materials. Controlling the size, shape of nanomaterials during nanoparticles synthesis leads to effective synthesis of nanoparticles that can be combatable to electrical system. Iron based nanoparticles are most efficient due to low cost and high adsorbent efficiency as compared to the other nanoparticles through the action of magnetic field with ionic exchange capacity for heavy metals removal. Nanofilters are used for filtering the chemical pollutants found in wastewater. Acid treatment leads to precise synthesis of nanoparticles through the formation of biopolymers that can be disintegrated into smaller components or individual’s molecules. Gold nanoparticles are also much reliable as compared to the other nanoparticles as they are more influenced by the intensity of light. Scanning tunneling microscopy has become technique to provide the electric data about the specific atom or particles by following the princes of scanning under chemical investigation. X-ray spectroscopy is used for the analysis of that analysis usually heavier than oxygen. Electron energy loss spectroscopy (EELS) that detect the particular nanoparticles by loos of energy by passing through the samples or specimen.
Sept. 18, 2021
The Modeling of Total Cost and Revenue in Stock Market on Economics
Page Numbers : 307-309
DOI : 10.36348/sjet.2021.v06i09.001
The relationship between investment and shares is established to find the intrinsic nature. It is found when the best labour is 6 the cost is low and the number of shares are 1000 with the intersection of 1~4 RMB which is net profit point. When the best capital is 6 units the profit will be 5 RMB and the profit point is 1400 of the number of shares with the 5 RMB. The profit may become the positive at 780 pieces when the best labor is one. It explains that beyond this point the total net profit may be 3~4 Yuan may be best net profit in average profit. TR£2TC that says the Tpro may be best start because TCquan£0 in intersection between Tpro and TC. The total profit will be 3~4 Yuan according to the best labor and capital. The best labor is 1 whilst the best capital is 6 in this condition. In total TR³2TC is the valid value to make more profit which is concluded in this paper.
Original Research Article
Aug. 30, 2021
Performance Characteristics of Clove Oil, Eugenol and Eugenyl Acetate as Bio-Additives in a Single Cylinder Diesel Engine
I.M. Hadi, I.S. Sintali, H. Dandakouta, A. Tokan
Page Numbers : 275-289
DOI : 10.36348/sjet.2021.v06i08.006
The performance of the fuels blends and emission levels were investigated under various operating conditions of the engine. Performance parameters like torque, brake power, brake thermal efficiency and brake specific fuel consumption (BSFC) were studied. Also, carbon dioxide (CO2), carbon monoxide (CO), hydrocarbon (HC), oxides of nitrogen (NOx), oxides of sulfur (SOx) emissions and exhaust gas temperature were investigated. The tests were carried out on a horizontal single-cylinder, 4-stroke, air-cooled, 4.00 kW engine, TD115 model. The results showed that blend of diesel and eugenyl acetate (BDEA 1.0%, 0.6% and 0.2%) gave the best performance in terms of reduced exhaust emission. The test results showed that, with decreasing speed, the torque of the engine fueled with both diesel and the blends increased with the maximum torque was recorded at 1680 rpm engine speed for BDE 0.2%. Also, there was a considerable increase in exhaust temperature with the blends compared to the diesel. The exhaust gas temperature of BDC 0.2%, 0.6%, 1.0%, BDEA 0.2% and BDEA 1.0% appeared to be similar to that of the diesel at all speed conditions. The research reveals that for a constant load of 1000 g, brake power increases with the increase in engine speed, thus a maximum brake power of 1.9 kW was obtained at 1680 rpm for BDEA 0.2%, this confirmed the results reported by researchers. There was an increase in the engine’s brake thermal efficiency when run on diesel and all the fuel blends at all speed conditions; however, BDEA 0.2% and BDEA 0.6% exhibited better combustion quality than diesel. The BSFC of the blends varied with the engine power and speed; therefore, for all the blends and diesel, consumption was high at low speed and vice-versa. The results also showed that the blends gave less CO compared to diesel. The minimum and maximum reduction of CO were 1.0 % and 1.5 % respectively of the blends, as compared to diesel. The emissions of NOx, SOx and CO2 decrease with increase in clove oil, eugenol and eugenyl acetate in the blends. All the findings compared favorably with the results of other researchers.
Original Research Article
Aug. 30, 2021
Electrochemical Techniques Assessment of Chloride Threshold for Reinforcing Steel Corrosion in Concrete Structures
Kelechi Okwulehie, Kpegara Saana N, Charles Kennedy
Page Numbers : 290-306
DOI : 10.36348/sjet.2021.v06i08.007
Corrosion of steel reinforcement in reinforced concrete is one of the most significant problems affecting structures and infrastructure worldwide, especially coastal structures. This study investigated the direct application of exudates/resin extract of Lannea coromandelica as a potential inhibitive material to control and prevent the corrosion of steel bars embedded in concrete structures and exposed to high salinity and acidic prone environments. The extruded exudates / resin is extracted from the tree and layered to reinforcing steel of different thicknesses. The hardened concrete slab is completely immersed in a 5% sodium chloride (NaCl) aqueous solution for 360 days with routinely checks, monitors and tested for 90 days, 180 days, 270 days, and 360 days of accelerated and corrosion process for comparative evaluation of both uncoated and coated samples. The maximum corrosion potential yields from the controlled and coated samples were -109.24mV and -114.16mV, indicating the relationship between corrosion potential and corrosion probability in the reference range 𝐸corr > −200mV. For non-coated samples, the calculated maximum value is -333.97mV, the result is within the reference value of the relationship between corrosion potential and corrosion probability of −350mV ≤ 𝐸corr ≤ −200mV indicates a high value range of 10% or less. The maximum calculated value of the controlled sample concrete resistance is 138.35% compared to the corroded and coated values of -56.56% and 153.43% and the maximum value of the control percentile difference is 24.97% compared to the corroded and coated value of 3.98% and 23.22%. The results of the controlled and layered concrete resistance samples obtained a maximum average value of 15.01kΩcm and 16.17kΩcm with a value of 10 < 𝜌 < 20 (low) compared to a corrosion value of 7.01kΩcm with a specification of 5 < 𝜌 < 10 (high) and with a reference range of the relationship between concrete resistance and corrosion probability and significant corrosion probability. The maximum computed percentile values of yield strength of controlled are 9.42% against corrode and coated values -8.03% and 9.57% respectively and the potential differential values of 0.71% controlled 0.71% corroded and 0.84% coated. The maximum computed percentile values of ultimate tensile strength of controlled are 1.68% against corrode and coated values -2.98% and 3.07% respectively and the potential differential values of 0.01% controlled, 0.00%% corroded, and 0.01% coated. Comparatively, the results of corroded samples showed reduction and decreased values in comparison of rebar diameter before and after induced accelerated corrosion test with values reduction percentile range from 0.038% to -0.895% and average ranges values from 11.98mm to 11.93mm. The reduction in average and percentile values showed that corrosion effects caused diameter reduction and cross-sectional area, fibre degradation, ribs reduction, and surface modifications whereas, exudates/resin coated members showed volumetric increase resulting from varying coating thicknesses. Conclusion: Summarized results showed that the effect of corrosion caused weight reduction/decreased in corroded samples as compared to coated with an exhibition of percentile and average value increase resulting in a volumetric minute increase from coating thicknesses.
Original Research Article
Aug. 21, 2021
Wenner Probe Technique Application in Electrical Resistivity and Corrosion Potential Measurements of Concrete Induced Chloride threshold Mechanism
Macmammah Michael, Charles Kennedy, Achieme Lewis Oba
Page Numbers : 259-274
DOI : 10.36348/sjet.2021.v06i08.005
The research evaluated Musanga cecropioides extrusion viscosity gummy paste (exudate/resin) obtained from trees as a corrosion inhibitor material to slow down the impact of corrosion on steel bars embedded in concrete and constructed in high-salinity coastal areas. The exudates/resin extracted is coated on the steel bar and embedded in the concrete slab, exposed to the corrosive medium with high salt concentration. The hardened concrete slab is completely immersed in a 5% aqueous sodium chloride (NaCl) solution, and the rapid corrosion process accelerated for 360 days with interval inspections and routine tests at 90 days, 180 days, 270 days, and 360 days for comparative evaluations for both uncoated and coated samples. The computed maximum control percentile value is -67.28% compared to the corroded and coated values 241.14% and -64.4% and the controlled potential difference value is 4.99%, corroded 60.25%, and coated 6.29%. The maximum yields of the controlled and coated samples were -105.1mV and -113.74mV, with the result obtained, this showed an indicative relationship between corrosion potential and probability as 𝐸corr > −200mV as the reference range. These results of potential Ecorr results showed indication that the values of controlled and exudates/ resin coated specimens are low with the range of 90% probability that no reinforcing steel corrosion is occurring in that area at the time of measurement (10% risk of corrosion which indicates a 10% or uncertain probability of corrosion. For the non-coated sample, the maximum obtained computed value is -328.64mV, the results are within the range reference of dependence between potential and corrosion probability of the value −350mV ≤ 𝐸corr ≤ −200mV indicating a high range of values, notifying a 10% or uncertain probability corrosion. The comparative results from the referencing range (controlled), showed that corroded samples exhibited corrosion presence resulting from the induced corrosion acceleration against coated samples that exhibited absence of corrosion. The exudates/resins exhibited inhibitory characteristics against corrosion attacks on reinforcing steel embedded in the concrete slab, exposed to corrosive media by the formation of the resistive coating. The maximum computed percentile of the controlled sample of concrete resistivity is 149.21% compared to the corroded and coated value of -59.26% and 153.52% and the maximum percentile difference of control is 5.38% compared to the corroded and coated value of 1.3 % and 8.09%. The results of the controlled and coated concrete resistivity samples obtained at an average maximum value of 15.85kΩcm and 16.23kΩcm with a data value of 10 <𝜌 <20 (low) compared to a corrosion value of 6.45kΩcm with specifications (𝜌 < 5, 5 < 𝜌 < 10, 10 < 𝜌 < 20, 𝜌 > 20) and with the reference range of the relationship between concrete resistivity and corrosion probability, the significant corrosion probability (𝜌 < 5, 5 < 𝜌 < 10, 10 < 𝜌 < 20, 𝜌 > 20) was very high, high, low to medium and low, for corrosion probability. The computed maximum percentile of the controlled yield strength is 8.96% compared to the corroded and coated values -7.83% and 9.08% and the possible difference values are 0.45% controlled, 0.49% corroded, and 0.59% coated. The maximum computed difference in values is 1.83MPa and 0.01% the controlled tensile strength is 3.478% against the corroded and coated values, respectively are -2.942% and 5.408% and the potential difference values 0.01% controlled, 0.01%% corroded and 0.01% coated. The yield strength, tensile strength, and strain ratio of the mean, percentile, and differential potential values of the control, uncoated (corroded) and coated concrete slab samples showed that coated samples had higher failure loads compared to corroded samples with reduced and decreased failure loads and low load-bearing capacity and with average values and percentiles to the reference range, while uncoated (corroded) samples recorded lower loads carrying capacity and reduced value compared to the reference range. The diameter of reinforcement after corrosion maximum computed percentile value is 0.039% as against -1.116% corroded and 1.128% coated; the difference in percentile is 0.005% corroded versus 0.008% coated. The results of the comparative of corroded samples show the reduction in values compared to the diameter of the reinforcement before and after the induction accelerated corrosion test with a percentile range for the reduction value from 0.039% to -1.116% and the average value in the range from 11.99mm to 11.94mm. The decrease/increase (diameter) in the cross-section of the minimum and maximum mean and percentile values were controlled 100%, with no decrease or increase in the description after 360 days of immersion in fresh water. The decrease in mean and percentile values indicates that the corrosion effect causes a reduction in diameter and cross-sectional area, fiber degradation, ..........