Authors:Kusuma Wardhani Mas'udah, Ahmad Taufiq, Sunaryono Sunaryono Pages: 220201 - 220201 Abstract: A simple chemical approach was developed to synthesize reduced graphene oxide (RGO) from corncob waste through the acid-base method with the addition of PEG-2000 at specific concentrations. The morphology and structure of RGO were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The process of reduction and quality of RGO were examined carefully with UV-Vis spectroscopy, infrared spectroscopy, and X-ray diffractometry. Based on the treatment and characterization, the diffraction data showed a prominent peak of RGO at a 2-theta position of 24.01°. The existence of C=C functional groups was detected in aromatic compound groups and alkene functional groups in aliphatic hydrocarbon compounds by infrared spectroscopy. The use of corncobs as the main raw material synthesized by an environmentally friendly route has tremendous potential in producing RGO that can be used as an efficient semiconductor material. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.1 Issue No:Vol. 54, No. 2 (2022)
Authors:Yohanes Edi Gunanto, Henni Sitompul, Maya Puspitasari Izaak, Yosep Sarwanto, Wisnu Ari Adi Pages: 220202 - 220202 Abstract: In this study, hexaferrite Ba0.95La0.05Fe12-2xZnxTixO19 (x = 0; 0.5; and 1.0) was synthesized and characterized, which can be applied as microwave absorber in the X-band frequency range. It is a potential candidate for a radar absorbing material for microwave absorption, particularly for use in anti-radar paint in the defense sector. Samples were prepared using solid state reaction synthesis with high energy milling. After sintering at the right temperature, the samples were characterized using an X-ray diffractometer (XRD), a scanning electron microscope (SEM), a vibrating-sample magnetometer (VSM) and vector network analysis (VNA). The XRD characterization results indicated that all samples were in phase and had a hexagonal lattice structure with a P63/mmc space group and a crystallite size between 38 and 45 nm. The surface morphology of the characterization results using SEM showed a heterogeneous particle shape with particle sizes ranging from 140 to 200 nm. Substitution of Ti4+ ions for Fe3+ ions by Zn2+ ions resulted in a decrease of the magnetic saturation (Ms), the magnetic remanence, and the sample’s coercivity field. With a sample thickness of 1.5 mm, the VNA results confirmed that the ability to absorb microwaves and bandwidth will increase along with increase of the substitution value x. The reflection loss value was about -13.3 dB at a frequency of around 11 GHz, with a bandwidth of 1.4 GHz for the sample with x = 1.0 composition. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.2 Issue No:Vol. 54, No. 2 (2022)
Authors:Dwina Roosmini, Eka Wardhani, Suprihanto Notodarmojo Pages: 220203 - 220203 Abstract: This research focused on the speciation and distribution patterns of cadmium in surface sediment from Saguling Lake, which is located in the Upper Citarum River. Organic compounds and heavy metals from anthropogenic activities in the watershed have contaminated the river. Sample from the upper layer of the sediment from Saguling Lake were taken from 12 locations, representing the dry and the rainy seasons in the period 2015-2018. Sediment cadmium (Cd) classification was conducted through a sequential extraction technique to determine Cd’s bioavailability and its risk to the water environment. During the rainy season, the total Cd concentration in the upper layer of the sediment was higher than during the dry season. The average dry and rainy season concentrations were 11.12 ± 2.16 mg/kg and 14.82 ± 1.48 mg/kgm in the sampling locations, distributed differently with the following order of the largest to the smallest concentration: 10B > 1A > 4 > 3 > 2 > 1B > 10A > 7 > 9 > 5 > 6 > 8 for the dry season, and 4 > 1A > 1B > 2 > 7 > 5 > 9 > 3 > 6 > 10A > 8 > 10B for the rainy season. All sampling locations (>60%) showed Cd in the resistant fraction, indicating no significant anthropogenic input of Cd into the surface sediment but more geological input due to high erosion. The values of RAC, ICF, and GFC indicate that the Cd in the surface sediment can be categorized as low risk. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.3 Issue No:Vol. 54, No. 2 (2022)
Authors:Muhamad Giri Suada, Hendri Syamsudin, Haroen Romadon Pages: 220204 - 220204 Abstract: The present work compared experimental and finite element analysis on the low-velocity impact response of a carbon/epoxy composite plate. Finite element analysis was based on the utilization of cohesive zone elements with the Benzeggagh-Kenane fracture criterion to predict the initiation and propagation of delamination. A Kirchhoff based formulation of a continuum shell element was used to model the stiffness of each lamina and the Hashim-Rotem damage mechanism to predict damages in every lamina. Five specimens of a 16-layer uni-directional carbon/epoxy composite plate with fiber orientation [+45°/90°/-45°/0°/+45°/90°/-45°/0°] s were subjected to low-velocity impact with a single energy value of 2.75 Joule/mm. The experimental results were then compared to the finite element results. Good agreement was achieved for the size and shape of the total projected delamination and visual damage to the top and bottom surface in the form of matrix and fiber failure. Slight differences were found for the dynamic response in the impact force history. Furthermore, a significant difference was found for the quantity of absorbed energy. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.4 Issue No:Vol. 54, No. 2 (2022)
Authors:Nura Shehu Aliyu Yaro, Madzlan Napiah, Muslich Hartadi Sutanto, Aliyu Usman, Intan Kumalasari Mizwar, Aliyu Mani Umar Pages: 220205 - 220205 Abstract: Palm oil clinker (POC) is a non-biodegradable palm mill by-product typically discarded in dumpsites. This study analyzed the performance of POC powder (POCF) as bitumen modifier in terms of conventional and engineering properties of bitumen and asphalt mixture. For the study, base bitumen of 60/70 penetration grade was utilized and different POCF dosages (0, 2, 4, 6, and 8% by weight of bitumen) were added. The base bitumen was effectively modified with POCF and then characterized. The conventional and engineering properties of the modified bitumen and asphalt mixtures were assessed. From the characterization results, the formation of Si-O crystalline structure and a new Si-OH functional group was identified. Furthermore, a meandering pattern was observed due to the modification of the base bitumen with POCF. Based on the conventional test results it was revealed that the addition of POCF to the base bitumen resulted in a stiffer blend compared to unmodified bitumen. The addition of POCF improved the modified mixtures’ Marshall stability relative to the unmodified mixtures. Analysis of variance (ANOVA) and regression modeling showed the influence and significance of POCF-MB, with R2 values of (95-99%). Finally, the 4-6% POCF dosage was found to be the optimum dosage, yielding the best performance in terms of the engineering properties evaluated. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.5 Issue No:Vol. 54, No. 2 (2022)
Authors:Sandro Mihradi, Andhika Dhaniswara, Satrio Wicaksono, Andi Isra Mahyuddin Pages: 220206 - 220206 Abstract: Bus rollover is considered the most dangerous road accident. To ensure bus safety against rollover accidents, the bus superstructure must conform to safety standards, one of which is UNR66. Unfortunately, in Indonesia, the increase in the number of buses has not been followed by bus safety improvement. In this paper, a numerical study on superstructure reinforcement to improve bus safety against rollover is presented. To reduce computational time, a simplified bus superstructure model comprising only three middle bays was used instead of a full bus model. Several superstructure reinforcements were implemented and their effectiveness in improving bus safety against rollover accidents was investigated. Among all reinforcements that were investigated, the most effective one was enhanced reinforcement by adding a connection between the seat structures and the side pillars. This modification yielded excellent results, as the modified superstructure showed a very significant improvement over a superstructure without reinforcement and it met the UNR66 residual space safety criterion. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.6 Issue No:Vol. 54, No. 2 (2022)
Authors:Viqhi Aswie, Lailatul Qadariyah, Mahfud Mahfud Pages: 220207 - 220207 Abstract: The reaction kinetics and the effect of power on microwave-assisted pyrolysis (MAP) in converting microalgae to biofuel were investigated to determine the decomposition mechanism and then characterize the best product. The resulting product consisted of three phases, namely liquid phase (bio-oil), solid residue (char), and uncondensable gas products. The results showed that the optimal increase in microwave power obtained was 20.57% with a 600-watt microwave power condition, a reaction time of 20 minutes, a microwave absorber to microalgae ratio of 1:6, and a heating rate of 25.96 K/min (600 watts). The reaction kinetics evaluated in the best condition showed a second-order reaction with activition energy (Ea) and pre-exponential factor (A) at 35.5971 kJ/moles and 2,606.75/minute, respectively. The characteristics of the biofuel product obtained were 1.01 gr/mL density, viscosity 10.97 cP, and pH 9.30. In addition, based on GC-MS analysis, the bio-oil contained aliphatic, aromatic, phenol, FAME, and polycyclic aromatic hydrocarbon (PAH) organic compounds. These results indicate that MAP has the potential to be developed as an alternative production process for biofuels. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.7 Issue No:Vol. 54, No. 2 (2022)
Authors:Anand Pai, Laxmikant Keni, Chandrakant R Kini Pages: 220208 - 220208 Abstract: AA6061, a popular structural material, has found widespread usage in the automotive and aerospace domains. The current work explored the effect of the improvement of mechanical properties on the machinability of AA6061 through finite element analysis. Three compositions of AA6061 containing 2 wt.% graphite and 0, 2, 4 wt.% granite dust were fabricated by stir casting. In the current work, a finite element model of a slab milling cutter with eight teeth was designed with high-speed steel (HSS) as the tool material. The LS-DYNA module of ANSYS was used for simulation of the milling operation, selecting two peripheral speeds for the cutter during the machining of the workpiece. Surface milling was carried out on the cast slabs of the three compositions to study chip formation. At higher cutting speeds, there was an increase in the von Mises stress as well as material deformation. An increase in the weight fraction of the ceramic fillers led to a corresponding increase in the von Mises stress and material deformation. The experimental results from face milling of the three compositions showed that the surface roughness increased with an increase in the content of ceramic fillers and a decrease in chip size. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.8 Issue No:Vol. 54, No. 2 (2022)
Authors:Hasan H. Ali, Firas M. Abdulsattar, Ahmed W. Mustafa Pages: 220209 - 220209 Abstract: The main objective of this study was to conduct a new and simple but accurate analysis of the dynamics of a crankshaft-connecting rod system based on Lagrange’s trigonometric identities. Actual and equivalent connecting rod mass approximations of single- and multi-cylinder reciprocating engines were studied. Several examples were studied to demonstrate the dynamics of the system. Lagrange’s trigonometric identities were used to simplify the model, while MATLAB was used to obtain the results. For both the proposed reduced model and the full model, the resultant forces and torques of an actual and an equivalent connecting rod mass were compared. The results showed that the proposed reduced model gives force and torque results that match the results of the full model very well. It was shown that the largest torque imbalance resultant on the crankshaft was exerted by the two-cylinder engine. In addition, it was shown that the largest external forces resultant acting in the x-direction was exerted by the one-cylinder engine. The results also revealed that the resultant of external forces acting in the y-direction was zero for multi-cylinder engines. The relative error, which mainly occurred at the points of maximum force and torque, ranged from about 1% to about 15%. PubDate: 2022-03-25 DOI: 10.5614/j.eng.technol.sci.2022.54.2.9 Issue No:Vol. 54, No. 2 (2022)
Authors:Eddy Agus Basuki, Nickolas Adrianto, Rahmadhani Triastomo, Akhmad Ardian Korda, Tria Laksana Achmad, Fadhli Muhammad, Djoko Hadi Prajitno Pages: 220210 - 220210 Abstract: This 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. PubDate: 2022-03-31 DOI: 10.5614/j.eng.technol.sci.2022.54.2.10 Issue No:Vol. 54, No. 2 (2022)
Authors:Yohannes Sampang Martua Simamora, Harijono A. Tjokronegoro, Edi Leksono, Irsan S. Brodjonegoro Pages: 220211 - 220211 Abstract: This paper presents an autonomous underwater vehicle (AUV) navigation scheme that pairs an inertial navigation system (INS) and a long baseline (LBL) acoustic positioning system. The INS is assigned to be the main navigation aid because of its faster rate. Meanwhile, the LBL provides position reference for compensation of the INS’ main inherent drawback, i.e., accumulating errors. However, the LBL has to deal with time-of-flight (ToF) measurements that may not be carried out under line-of-sight (LoS) circumstances. This is because the propagation speed of underwater acoustic waves is subject to the sound-speed-profile (SSP) of the area in question. This paper’s contribution is to consider the SSP in ToFs while addressing the above scheme. Specifically, the discrete approach to raytracing was implemented. For a given ToF, the Snell’s parameter of the wave is estimated and subsequently used to compute the horizontal range. The ToF results are then used to estimate the position of the AUV, while the position is obtained from a depth sensor. It was shown by simulation that the estimators can provide navigation with accuracy <0.5 m2, as it manages to compensate for errors. Since the estimation of Snell’s parameter is prone to exhibit imaginary numbers, future work should consider a more robust method to tackle this problem. PubDate: 2022-03-31 DOI: 10.5614/j.eng.technol.sci.2022.54.2.11 Issue No:Vol. 54, No. 2 (2022)
Authors:Ze Gan, Xi Yang, Yunpeng Zhang, Xu Wu, Jie Wang Pages: 220212 - 220212 Abstract: Blasting is used as an economical tool for rock excavation in mines. However, part of the explosive energy is converted into elastic waves, resulting in ground vibration and excessive vibration, which may cause damage to nearby buildings. Meanwhile, toxic gases are also produced during the explosion. In this paper, an environment-friendly method for rock excavation is proposed. A series of vibration tests were conducted, and the peak particle velocity was monitored. The results showed that the proposed method can replace the conventional blasting method in mines. Besides that, the vibration caused by the proposed method is much smaller than by the conventional method. By adjusting the direction of the high-pressure gas injection, buildings around the mine can be protected well from vibration. Also, the production of toxic gases during excavation will no longer be a problem. Thus, a milder environmental impact can be achieved. However, the rocks excavated by the proposed method are relatively large, which still need to be broken further. On this issue, further study is required. PubDate: 2022-03-31 DOI: 10.5614/j.eng.technol.sci.2022.54.2.12 Issue No:Vol. 54, No. 2 (2022)
Authors:Santi Puspitasari, Adi Cifriadi Pages: 220213 - 220213 Abstract: Lignin has high potential to be used as rubber cushion gum compound ingredient due to its unique properties. Cushion gum is an adhesive used to bind a new tread to the surface of used tires in a retread tire factory. An experiment was carried out to evaluate the performance of hybrid filler consisting of carbon black and lignin in affecting the physical and mechanical properties of natural rubber (NR) based cushion gum composite. The composition of carbon black/lignin was arranged at 40/10 phr and 35/15 phr. Carbon black grade N220, N330, and N550 were used in this research. Meanwhile, the lignin was specifically in the form of sodium lignosulfonate. The cushion gum compound was also formulated with the addition of pine tar oil as bio-based plasticizer. Commercial cushion gum was used as a comparison. The result showed that the hybrid filled NR cushion gum composite with N330/lignin at 40/10 (coded as SP2) was the most appropriate formula. Compared to commercial cushion gum, the SP2 hybrid filled cushion gum had comparable or even better processability and mechanical properties, attributed to high crosslink density. The excellent adhesive strength of the SP2 NR cushion gum composite was due to the presence of high content of the phenolic functional group in lignin and pine tar oil. PubDate: 2022-03-31 DOI: 10.5614/j.eng.technol.sci.2022.54.2.13 Issue No:Vol. 54, No. 2 (2022)
Authors:Nikolay Masalsky Pages: 220214 - 220214 Abstract: Silicon nanowire field-effect transistors are discussed as biological sensors due to their excellent sensitivity due to the large surface-to-volume ratio and high selectivity with respect to a large number of analytes. A miniature sensor based on a long-channel fin field-effect transistor as a surface charge detector is being investigated. The three-gate configuration offers undeniable advantages over planar devices, since the edges are about a hundred nanometers wide and are characterized by increased conductivity, which leads to higher sensitivity. The characteristics of the transistor are optimized using 3D modeling performed by the computer-aided design software package TCAD, depending on the topological parameters of the transistor and the level of control voltages. Based on the obtained simulation results, a chip was manufactured on a SOI substrate based on self-aligning CMOS-compatible technological processes from top to bottom. It is established that thin structures with a reduced level of doping and low supply power have promising electrical characteristics for an effective approach to scaling a high-resolution pH sensor, which is of particular interest to integrated pH bioanalytics based on CMOS technology. PubDate: 2022-03-31 DOI: 10.5614/j.eng.technol.sci.2022.54.2.14 Issue No:Vol. 54, No. 2 (2022)
Open Access journal
