bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of solvent polarity during electrodeposition of asphaltenes from a Colombian oil in the presence of a magnetic field and magnetic nanoparticles
Authors: Roa M , Amaya I , Correa R
Published: August 2020

This work focuses on analyzing the electrokinetic behavior of asphaltenes of extra heavy oil. For this, electrodepositions were carried out in asphaltene solutions (4 %w/w) with two solvents of different polarities: toluene and chloroform. In addition, we worked with different magnetic fields, and the effect of adding 1% w/w of magnetic nanoparticles was analyzed. The asphaltenes were extracted with heptane and were characterized by infrared and ultraviolet visible spectroscopy. In the case of toluene, the initial adsorption (without fields) was 4 mg in both anode and cathode. By using an electric field (100 V/m) the deposits increased to 6 mg (anode) and 5 mg (cathode). However, when using a static magnetic field of 0.1 mT, no changes were observed. But, by modifying said field by a dynamic one (0.1 mT and 60 Hz), 15 mg (anode) and 19 mg (cathode) were obtained. Moreover, the addition of nanoparticles (previously characterized by scanning electron microscopy and X ray diffraction) changed the behavior, worsening in the absence of fields, and improving only in the presence of the dynamic field (104 mg, 26 mg in anode and cathode, respectively). Similar results were obtained when using chloroform. Thus, the best performance was obtained by using a dynamic magnetic field. By not considering the nanoparticles, total deposits increased more than 14 times (102 mg versus 7 mg). However, considering them, the increase was greater than 30 times (302 mg versus 10 mg). Therefore, we consider that adding nanoparticles, and supporting the electrodeposition process with a dynamic magnetic field, is an alternative that must be included to improve process performance.
Dynamic and sequential update for time series forecasting
Authors: Gallardo Pérez H J , Vergel Ortega M , Rojas-Suárez J P
Published: August 2020

Two different sciences, physics and statistics, have worked, from the foundations of each, on the explanation and modelling of stochastic processes characterized by the succession of random variables whose realizations at each instant of time give rise to time series. From Physics we have worked with the Fourier transform to explain the dynamics of time series, a similar case occurs from statistics where dynamic models of time series are worked to explain the variations of the series and, in both cases, to make reliable forecasts. The main objective of this research is to adjust a model, using the methodology framed in the sequential update procedure of the forecast, to a time series of coal production observed quarterly during the years 2007 to 2011, in order to disaggregate quarterly the annual production for the years 2012 to 2018. Once the process has been carried out and validated, a quarterly production model is estimated which allows valid and reliable forecasts to be made for each quarter in subsequent years.
Application of data mining as a tool in computer science
Authors: Velásquez-Pérez T , Camargo-Pérez J A , Quintero-Quintero E L
Published: August 2020

Computational science involves a systemic approach for adequate management of both information and knowledge; through theories of information and computation. Today trends such as big data and data mining emerge, with which behavior patterns previously only visible to the human eye can be established. This article, part of the analysis of big data, based on research found on the science websites, whose objective was based on knowing the conceptual evolution of Big data as well as the search for statistically regular behaviors over time in different elements related to the production and consumption of scientific information. For this study, data mining will be specified for Big data analysis, resulting in instructions to identify and understand trends and patterns within the different research areas.
Measuring the quality of the blended learning approach to teaching computational sciences
Authors: Perez B , Castellanos C , Correal D
Published: August 2020

Teaching models are a very interesting area of study that can be applied to any science. Finding the best way to transfer knowledge to students, so that they internalize it and can successfully transfer it to the field, is key to the country building. This article measures the quality of a teaching model that can be applied in physics or engineering, which requires a correct theoretical foundation before addressing practical elements. Blended learning is an approach to education that combines online educational materials and opportunities for interaction online with traditional place-based classroom methods. This model was applied in agile software architectures course and measured through an anonymous survey of students in software architecture, who were enrolled for the periods 2015-2018. The results showed that 39.7% of the respondents considered that they learned better compared to face-to-face courses.
Failure study as a physical component in mechanical suspensions of two automobile models of an automotive company
Authors: Serrano-Rincón C A , Navarro Torrado L , Florez-Solano E
Published: August 2020

Car suspensions are a key element for the good behavior of cars. There are many types with their advantages and disadvantages, but among them, the most used and known today is the MacPherson strut suspension. The MacPherson strut is a system devised by Earle S. MacPherson in the 40s and patented by Ford in 1953, which today is used for the front axle of most cars. This type of suspension is very versatile because it can be used on the rear as well as front axles, and because of its low cost. These types of vehicles present many breakdowns on these pieces in the municipality of “Ocaña, Norte de Santander, Colombia” since the type of terrain is very complex (steep slopes, poor condition of the roads, among others), which leads to breakdowns on the pieces due to shear stresses, which could cause a traffic accident and high repair costs. This work seeks to show the identification of the vehicles that use the MacPherson strut and its possible failures. Subsequently, the analysis of the stresses on the lower arm system of the MacPherson strut is carried out in compact cars using simulation software. to perform the physical analysis behavior.
Numerical Calculation of the Radiated Noise of Contrarotating Propellers
Authors: He Xiaohui , Liu Zhongle , Wang Xianyong , Yuan Zhiyong
Published: August 2020

Based on the hybrid methods of cavitation transient simulation of multiphase flow and the boundary element numerical acoustic calculation, the noise of contrarotating propellers in states of cavitation and non-cavitation is calculated, the increase quantity of the noise spectrum level in cavitation relative to in non-cavitation condition is analyzed; the calculated noise value and the tested value are compared. The multiphase flow transient simulation includes three simulations: unsteady Reynolds-averaged Navier-Stokes method (URANS), scale adaptive simulation (SAS) and detached eddy simulation (DES). The testing result shows that the open water performance curve of propellers coincides well with the experimental result in the range of large range of feed coefficient. SAS presents a comparable ability with DES in capturing the pulsating pressure of cavitation and can respond well to the unsteady load noise. RANS (Reynolds-averaged Navier-Stokes) is appropriate for the low frequency noise. The calculating error of line spectrum cavitation volume pulsation 1 kHz is less than4.23 dB, and the average error of spectrum level 1/3 Octave band is less than1.83dB in the frequency band of 1 kHz-3kHz, and the predicted error of the total sound pressure level is less than 2.74dB, And the attenuation coefficient of sound pressure level with is calculated by simulation, which can provide certain help for the design and the noise prediction of propellers.
Research on Solving Ionization Equation of High-Speed Aircraft Based on Euler Monte Carlo Method of Fluid Mechanics
Authors: Lu Ming
Published: August 2020

Taking the aerodynamic calculation of high-speed aircraft as an example, this paper introduces the modelling and application of computational fluid dynamics in aircraft design. The application of computational fluid dynamics in the design of aircraft is accompanied by the development of computer technology and aerodynamics. From the earlier solution of the Euler equation and the NS equation from a macro perspective, to the solution of the NS equation with chemical reactions and ionization that considers the influence of real gases, and from the micro perspective, the Monte Carlo method is used to directly simulate and solve the gas molecule motion, that is, It represents the development of computational dynamics theory and is also the result of the development of computer technology today. This article discusses the application of computational fluid mechanics, including the selection of mathematical models, the selection of calculation methods, and its application to special problems in aircraft design.
Effect of Surface Texture Distribution Parameters on Hydrodynamic Lubrication and Numerical Optimization
Authors: Huang Fengyun , Yang Xiaobing , Zhu Jiwei , Xu Jinli
Published: August 2020

Surface texture technology has been proven to be an effective way to improve the lubrication performance of friction surfaces. In order to obtain the optimal surface texture distribution parameters, taking the spherical crown pit texture model as the research object, and selecting the unequal rectangular control unit to establish the surface texture distribution model with different horizontal and vertical distribution distances (densities).According to the principle of fluid dynamic pressure lubrication, a two-dimensional Reynolds equation based on the N-S equation is established and solved by the multigrid method to study the effect of texture distribution parameters on the surface hydrodynamic lubrication under plane motion. The results show that when the texture unit Lx is 3.4r and the aspect ratio Ly / Lx is 0.82, the optimal oil film bearing capacity can be obtained. When the control unit of the boundary pit is appropriately increased so that the left and right sides of the pit at the boundary are about 3.4r, the oil film pressure stability can be effectively improved.
Research on the Significant Effect of Nozzle’s Structure on Air Outlet Speed Based on Numerical Simulation
Authors: Hao Guangfa , Zhang Chengliang , Sun Kang , Li Lei , Zhou Jun
Published: August 2020

Aiming at the problems of short spray distance and poor atomization effect in pesticide spraying. In addition, in order to enhance the initial velocity of the droplets and the secondary atomization of the droplets, a new air-driven combined electrostatic nozzle based on the Venturi effect is designed in this paper. And a method for accelerating and atomizing mist droplets using the Venturi effect is proposed. Combined with the distribution of airflow from the venturi, the acceleration and atomization effects of the nozzle were verified and analyzed. Using the factor design test method, three structural parameters, namely the distance A from the nozzle outlet to the venturi mouth, the retracting radius B of the venturi mouth, and the extension distance C of the venturi mouth were tested, and the following conclusions were drawn. At the 1% significance level, the single factors A, B, and C have significant effects on the average velocity of the venturi throat. The interaction of two factors, AB, AC, and BC, had no significant effect on the average velocity of the venturi throat. The interaction of three factors ABC has a significant effect on the average velocity of the venturi throat.
High-fidelity Numerical Study on Air-tightness Detection System of Medicine Box
Authors: Mao Changyong , Wu Weimin , Xie Yangjun , Dai Jiushuang , Zhao Qilin , Dai Qiuhong
Published: August 2020

Planning an automatic detection system of the air tightness of medicine box is very necessary for growing demand for storage of pharmaceutical products. In this study, the high-fidelity CFD study is performed for the air tightness of the medicine box, using the LBM algorithm. The high-fidelity results indicate that after about 5.24 s, the stable value of the average static pressure of the ring cavity remains at about -9414 Pa. The slit flow in the early stage of micro-leakage is very complicated, especially for the initial stage. The location of the micro-leakage is concentrated in the directions of 1 o’clock, 4 o’clock, 7 o’clock and 11 o’clock along such edge of the end cap, therefore, the sealed end cover needs to be further improved. Additionally, the idea of this research work can provide a good basis and reference for the subsequent series of related airtightness studies.
Effect of Closure Coefficients of K-Ω SST Turbulence Model on Predicting Stall Characteristics of The Airfoil
Authors: Liang Changping
Published: August 2020

The two-dimensional numerical simulation for NACA0015 airfoil and S325 airfoil were conducted with k-ω SST turbulence model. For the k-ω SST turbulence model could not predict the airfoil stall characteristics accurately, the non-equilibrium turbulence transport nature was systematically analyzed. The study showed that: the turbulent viscosity scope simulated by the original k-ω SST turbulence model was smaller which resulting in the model could not accurately simulate the turbulence transport properties in the separation zone; By increasing β* or decreasing α1 can improve the capabilities for predicting the transport characteristics of non-equilibrium turbulent, and then improve the accuracy of numerical simulation for stall characteristics of the airfoil, it also helps to improve the accuracy of numerical simulation of wind turbine blades.
Study on Calculation of the Buoyancy Drag Coefficient in the High-Speed Wind Tunnel Test
Authors: Chen Xuekong , Wei Zhi , Liu Guangyuan
Published: August 2020

In order to obtain the drag coefficient in accuracy, it needs to correct the model’s buoyancy drag coefficient in the high-speed wind tunnel test. However, there are several methods on calculating the buoyancy drag coefficient, each will generate a result differently. Three types of methods are studied in this paper, the formulas are derived, the buoyancy drag coefficients are calculated, and the results are compared in the end. It shows that the most exact method is the one based on pressure fitting function, it’s suitable for correcting the model’s drag coefficient with high accuracy requirement.
Simulation of temperature field of A356 aluminum alloy in freeze casting
Authors: Yang Haoqin , Shan Zhongde , Wang Yifei , Liu Limin
Published: August 2020

In this paper, the temperature change curve of the casting and frozen sand mould during the solidification process of the A356 aluminum alloy in the frozen sand mould is tested. According to the actual temperature change curve of the casting surface and the sand mould surface, the interface heat transfer coefficient between the frozen sand mould and the A356 aluminum alloy could be reversed analysis. The results show that when the casting temperature is lower than 550 °C, the interface heat transfer coefficient remains about 750 W.(m2.K)-1; When the casting temperature is between 550 °C and 610 °C, the interface heat transfer coefficient increases significantly; when the casting temperature is higher than 610 °C, the interface heat transfer coefficient reaches the maximum value, which is about 2300W. (m2.K) -1. At this time, this study simulates the solidification temperature field of aluminum alloy hub parts in the frozen sand mould according to the interface heat transfer coefficient calculated by inverse analysis, and the temperature field of resin sand mould casting was used as for comparison. The results show that: under the same solidification time, the temperature field of A356 aluminum alloy hub parts in frozen sand mould is lower than that of resin sand casting, freezing casting can realize the high-speed solidification process of different parts of complex castings.
Experimental study on heat transfer characteristics of flow on an inclined hot metal plate
Authors: Xiong Muwen , Zhang Jiaqing , Wang Qing , Zhao Senlin , Wang Guanjian , Wen Pei , Han Jiao , Shi Xiangjian
Published: August 2020

In order to deeply understand the heat transfer characteristics of water and foam at high temperature with different inclination angles and initial surface temperature, pure water and foam were selected to conduct experimental research on high temperature surface liquid flow with inclination angles of 45 ° and 70 ° and initial surface temperature of 110 ° C, 210 ° C, and 310 ° C. It is found that the difference between the flow pattern and heat transfer of pure water and foam on the surface of high temperature metal plates is more obvious when the surface initial temperature is higher. The water flow form horseshoe-shaped low temperature region with the lateral width increasing and the longitudinal length decreasing on the higher temperature surface. The foam on the high-temperature surface is mainly cooled by the strip shaped area flowing in the mainstream direction; the length of the cooling area covered by the foam of the high-temperature surface is significantly longer than pure water.
Numerical simulation of micro-nano bubble central intake aeration
Authors: Rong Xiaojie , Wang Qi , Ren Liuyi
Published: August 2020

In this paper, ANSYS FLUENT was used to simulate the gas-liquid two-phase flow in the process of micro-nano bubble aeration and optimized the central air intake aeration conditions. The particle size of microbubbles was 2 μm, the Eulerian model was used in multiphase flow model, and the standard k - ε model was used in turbulence model. The gas-liquid two-phase flow field with different aeration velocity was simulated. The effects of aeration time on gas holdup were studied. The results showed that the aeration effect was better with the increase of aeration speed, stronger turbulence, two-phase mixing and oxygen mass transfer.
Research on the Innovative Talents in “Double First-Class” Universities under Artificial Intelligence Technology
Authors: Song Wanying , Min Jian
Published: August 2020

With the continuous integration of artificial intelligence technology and management disciplines, the emergence of new technologies and new concepts put forward new requirements for the cultivation of cross-disciplinary talents in management disciplines. At the same time, strengthening the development of cross-disciplinary integration is also a vital part of the “Double First-Class” universities construction. This article points out that the application direction of artificial intelligence technology in innovative talents of management discipline can be divided into three levels: computational intelligence, perceptual intelligence, and cognitive intelligence. Based on the three levels, formulated innovative talents in the management discipline cross-cultivation model that integrates innovation quality orientation, innovation performance orientation and innovation contribution orientation, designed a talent training operation mechanism based on multi-subject collaboration, facing the new education ecology in the era of artificial intelligence.
Drag Prediction of Nasa Common Research Model Under Stochastic Inflow Conditions
Authors: Wu Xiaojun , Chen Jiangtao , Hu Xingzhi , Li Huan , Zhang Chao
Published: August 2020

Numerical investigations of NASA Common Research Model under stochastic inflow conditions are analysed in this paper by Non-intrusive Polynomial Chaos (NIPC) method. Reynolds number, Mach number and temperature of inflow conditions are assumed to be independent stochastic variables. It is found that predicted drag mainly depends on Mach number of incoming flow. The contribution of Reynolds number and temperature to the variance of drag is negligible. The mean value of drag shows consistent convergence with grid refinement. The investigation of this paper quantitates the uncertainty induced by stochastic inflow conditions to drag prediction and recognizes the most significant input variable. This will help the validation of numerical methods with experiment.
Preliminary design of laboratory experiment on flow pattern in natural-like fish way ponds
Authors: Huang Zhigang
Published: August 2020

In the design of fish way, the flow pattern of the pool is an important design basis. Many factors need to be considered in the preliminary test of fish way in the laboratory. This paper introduces the design method and preliminary results of flow measurement test of fish way pond chamber. The results show that the layout and porosity of the partition wall should be considered in the design of natural fish way. Different partition arrangements and porosities have obvious influence on the flow pattern in the pool. In the flow pattern of the pool chamber, there is a clear main flow, but the flow rate is low behind the partition wall and near the side wall of the pool chamber.
A Second Order IMEX Method for Radiation Hydrodynamics
Authors: Zhao Yang
Published: August 2020

Radiation hydrodynamics problem is mulitphysics field coupled and challenge in mathematics. A new scheme, IMEX, is put forward in solving RHD equations when the explicit method have an extremely small time step and implicit method have a complicated and high cost solver. RHD equations are solving by splitting the explicit operator and implicit operator with IMEX scheme. The results of Riemann problems are plotted and the scheme shows the effect to lower the computation cost.
Experimental research on collector effect on operating characteristics of high-speed free-jet wind tunnel
Authors: Zhao Fang , Qing Honggang , Ren Zebin , Li Yi
Published: August 2020

Collector is one of the key parts of the high-speed free-jet wind tunnel, which directly affects the performance of wind tunnel. In this paper, a small high-speed free-jet wind tunnel is used as the test platform to carry out the start-up and operation characteristics test of wind tunnel. Start-up pressure characteristics were obtained at various Mach number, and the influence of the collector throat heights and collector positions on start-up pressure and matching pressure was preliminarily studied. The results show that the high collector throat height can meet the requirements of wind tunnel start-up and pressure matching. The closer the collector is to the nozzle, the smaller the corresponding starting pressure and matching pressure. However, this trend weakens with the decrease of Mach number, which lays a foundation for the development of large high-speed free jet equipment.
A mock circulation loop for in vitro haemodynamic evaluation of aorta
Authors: Li Xuhui , Li Zhenfeng , Chen Duanduan
Published: August 2020

Haemodynamic conditions play a crucial role in the pathological development of aortic dissection (AD). However, it is challenging to quantitatively and precisely capture the flow features in vivo. In this study, a mock circulation loop (MCL) embedded with patient-specific aortic phantoms was proposed. In order to evaluate perfusion characters, a normal aortic model and an AD model were established with twelve main branches. The system is capable of replicating the aortic geometry, vascular compliance, characteristic resistance, and peripheral resistance of the cardiovascular system. By altering controlling parameters, it can mimic various cardiovascular conditions. The physiological healthy rest cardiac condition was reproduced and the rationality and accuracy of the system was confirmed by comparing the measured flow data from the MCL with a normal aortic phantom and the in vivo ultrasound velocimetry of healthy volunteers (maximum discrepancy was 4.69%). Different flow features between the normal and AD phantoms were quantitatively compared by pressure sensors and ultrasonic flow sensors under the same condition. Therefore, the proposed MCL can be applied as a research tool for in vitro haemodynamic analysis of the aorta. Moreover, it can be applied to evaluate the performance of interventional devices and to provide a realistic platform for trainings on interventional treatments.
Study of a microfluidic chip with converse fluid
Authors: Song Feifei , Ma Yuting , Wu Yunliang , Wang Ce
Published: August 2020

The current microfluidic chip design generally forms a stagnation point in the exit flow area of the microfluidic chip. The presence of the stagnation area can cause problems such as choke of channel and sample purity degradation. For this problem, a microfluidic chip with converse fluid was designed. The converse sheath liquid can avoid the adverse effects caused by the presence of the stagnation point. It can prevent the cells from contacting the wall surface, and avoid the blocking problem of cell. At the same time, the introduction of the converse sheath liquid can also focus the sample flow in the sorting channel and the waste channel again, which is convenient for the detection of the sorted sample. The fluid flow state in this microfluidic chip was also simulated, and it verified the benefit of introducing converse sheath fluid, which has reference value for the design of microfluidic chip for cell analysis and sorting.
Numerical Simulation for Creep Characteristics of Soft and Hard Interphase Rock Mass
Authors: Han Bing , Fu Qiang , Wang Chunyan
Published: August 2020

By using the simulated software FLAC3D, triaxial creep simulation experiments are conducted on soft and hard interbedded rock bodies under different stress levels and loading paths, and the effects of stress state and loading method on the time-dependent characteristics of soft and hard interbedded rock bodies are studied. The established model is analyzed with the method of 3-D visco-elasto-plastic numerical simulation. The results have shown that under the same stress level the deformation and volumes of plastic zone of rock mass will expand when the amounts of soft rock layers increase or the gradient of soft rock layers is steeper.
Non-real eigenvalues of a class of fourth order discontinuous differential operators with indefinite weight function
Authors: Zhao Xin , Liu Dejun , Xu Xiaoli
Published: August 2020

The spectral theory of differential operators is one of the basic problems of differential operator theory. It has been an important tool in quantum mechanics and other fields. For the Sturm-Liouville Problems with weighted functions, the spectral theory of right-definite problems with self-adjoint boundary condition has been accomplished. But the spectral structure of indefinite problems, is quite different from and more complicated than that of right-definite problems. Compare with second order case, much less known for the fourth order indefinite differential operators. The present paper discusses a class of fourth order discontinuous differential operators. We obtained the estimate on the non-real eigenvalues, under separated boundary condition and the condition that weighted functions change signs for only once or any times.
Experiment of Measuring Half-wave Voltage and Electro-optic Coefficient of Crystal Based on KDP Crystal
Authors: Wu Yutong , Su Bo
Published: August 2020

The paper aims to measure half-wave voltage of KDP crystal irradiated by a 532 nm red laser. This paper explores a safe and easy way to measure the electro-optic coefficient, and then calculates the electro-optic coefficient of the KDP crystal. It provides a feasible way to measure the half-wave voltage and electro-optic coefficient of different electro-optic crystal materials by laser with different wavelengths.
Effect of the Angle of the Crossed Fibres of a Fog Harvester on its Collection Efficiency
Authors: Jia Zhen , Zuo Zhigang , Liu Shuhong
Published: August 2020

Although fog harvesting technology was firstly invented in the 1980s, the theoretical research is still in its infancy. To enhance the collection efficiency of fog harvester, lots of work have been done such as surface modification and 3D structure of the fibres of the fog harvester. In this study, based on observation of daily phenomenon, relationships between the angle of crossed fibres of the fog harvester between collection efficiency are discussed. Results show that as the angle of fibres changes, the effective collection rate per unit length of the fibre keeps unchanged, except near the maximum/minimum limits of the angle, where the collection rate drop significantly, caused by clogging according to the experimental observations. It is also found that the existence of fibre node will influence the collecting process of fog harvester, which can explain why harp-like fog harvester performs well in fog collection.
The Necessity to Assess the Electromagnetic Environment Near 5-G Radio-Emitting Objects with Instrumental Procedure
Authors: Zvezdina M Yu , Shokova Yu A , Prygunov A G , Palyanitsa A A , Sumin D L
Published: August 2020

The features of the new 5G standard if compared to the currently used 4G lie within a significant frequency range expansion, and the implementation of the Internet of things. They made it impossible to expand the existing safety standard of broadband cellular network construction in large cities to the new standard. Differences between the Western and Russian approaches to the maximum permissible power level assessment and the lack of publications on the subject prompt measurement experiments in order to obtain an approximate electromagnetic environment assess near radio-emitting objects. At the preliminary stage of the measurements, it is necessary to choose the right measuring instruments and procedures, since the choice determines the price-quality relationship of the experiment. In the paper the results of the analysis for the known measuring instruments are given with an account to the special requirements formulated according to 5G standard features. The conclusion on the availability of the measuring instruments with the required characteristics is made. It is shown that the experiment efficiency depends on the measurement area dimensions and the measurement points spacing. In case of reflector antenna of 0.9 m diameter operating at 6 GHz the number of measurement points can be reduced without a loss of accuracy if the measured antenna passport data as well as the recommendations given in the paper are taken into an account.
Solar-diesel hybrid power plant battery charging systems
Authors: Sau Matius , Patoding Hestikah Eirene , Kasa Agustina
Published: August 2020

This study aims to examine the charging current of a solar energy hybrid generator with a Genset / Diesel and the time used to fill the accumulator in conditions without load and load conditions. The results showed that the solar energy hybrid generator and Genset / Diesel prototypes were able to produce electrical power at 08.00 - 17.00 in the average sunny weather of 290.7 Wp without loading and at the time of load of 236.4 Wp. At night, the energy stored in the battery is converted into electrical energy to supply the load. Thus it can save electrical energy.
Study of microwaves energy conversion into electric current on semiconductor material NaxCuyTiz
Authors: Jayanti Regna Tri , Haryati Sri , Bustan M. Djoni
Published: August 2020

Converting microwaves energy into electric current has been studied through co-precipitation and sintering process on the semiconductor material. Most of the application of these methods still had a challenge of lowering the resistivity value of semiconductor material. Some researches indicated by adding molten salt into semiconductor material can reduce the resistivity value. In this study, the synthesis process by combining the co-precipitation and sintering method of transition metal (titanium and copper) and alkali metal (Sodium) shown an improvement in lowering resistivity problems. Composition ratio, temperature, and distance of radiation were the variable of measurement in this research. Three semiconductor materials NaxCuyTiz were synthesized by using 60 ml of hydrochloric acid (HCl) and 80 ml of ammonium hydroxide (NH4OH) as a reagent in co-precipitation method and sintering at temperature 500°C. An Olympus microscope was used to analyze the microstructures of all three materials. Fractions x, y, and z in the materials were determined by analysis of X-ray spectrograph model 2501. The resistivity values of three materials, namely as Na0.52Cu0.37Ti0.11, Na0.26Cu0.39Ti0.35, and Na0.26Cu0.67Ti0.07 were obtained by varying the temperature of measurement. The microwave radiation was measured by observing the output voltage and current along with the radiation at a variable distance (60, 90, 10, 150, 180, and 210 cm) through the semiconductor material. The experiment showed that material Na0.52Cu0.37Ti0.11 had low resistivity and small bandgap energy as 0.875 eV and able to convert microwave energy from 1.624 × 10−24 Watt to 9.137 Watt at 60 cm of microwaves radiation distance.
The effect of active carbon adsorbents from some wastes in reducing free fatty acids and acid number to improve vco quality
Authors: Simatupang Dimas Frananta , Tarigan Jenny , Mansyur
Published: August 2020

The use of several wastes such as durian outer skin, cassava outer skin and corncobs could be used to improve VCO quality. The wastes were converted into activated carbon as an adsorbent that was activated using sodium carbonate in purifying VCO in terms of reducing free fatty acid (FFA) and acid number. VCO used was oil that has made directly in the laboratory of oleo chemistry PTKI Medan and tested to reduce level of FFA and acid numbers. A total of 5 ml VCO samples were used to determine reducing in level of FFA and acid numbers by a titrimetric method with three times repetition using 0.1 N NaOH and previously treated with activated carbon adsorbent from durian outer skin, cassava outer skin and corncobs as much as 1 gr, 2 gr, and 3 gr. Based on the results of the examination, it was found that the level of FFA and acid number of VCO had a significant decrease with the best-activated carbon adsorbent using waste from cassava outer skin where level of FFA decreased by 0.16% and acid number decreased by 0.448.
Application of air conditioner (AC) automation system on arduino flatform-based vehicle
Authors: Randis  , Wijaya S H
Published: August 2020

This study aims to design and create a safety device and automation system in the use of air conditioner (ac) use in-vehicle units, especially in four-wheeled vehicles based on Arduino UNO microcontroller Atmega 328. The safety device system created in this study used Arduino UNO as its microcontroller, a tool was equipped with a PIR sensor that was positioned in the cabin and a limit switch placed at the door of the vehicle. If there are humans inside the vehicle unit, the PI sensor will detect movement, and if the unit door is in the closed position, the limit switch will be depressed. The principle used the AND logic gate principle where both inputs both the PIR sensor and the limit switch must work together to turn on the AC, but if only one input works, then the AC will not turn on. The results of this study indicated the tool could work under the design that has been done, and the programming of the safety device can work well according to the desired working principles through the programming commands on the Arduino UNO microcontroller.
Effect of Typical Lubrication on the Pressure Ratio Through Operating the EFI Suzuki Engine
Authors: Sihombing R , Hidayat  , Fatmawati A , Nur R
Published: August 2020

Many types of lubricants was used as a lubricant in the Suzuki Baleno EFI engine. There is some questions in the community which better lubricants are used without prior research. This paper aims to determine the pressure ratio produced by the Suzuki Baleno EFI engine by using different lubricants. The experimental method was used in this study by testing two lubricants (i.e. SAE 30 and SAE 40) and comparing the ratio of the pressure produced. The results showed that the ratio of the pressure produced between lubricants of SAE 30 : SAE 40 was 1: 1.5 at 800 rpm; 1: 1 at 1500 rpm; 1: 1.06 at 2000 rpm and 1.1: 1 at 2500 rpm. T-test was used to compare the significance of the use of SAE 30 and SAE 40 as lubricants on the pressure ratio through operating the EFI Suzuki Engine. It can be concluded that the SAE 40 lubricant will produce a greater pressure compared to SAE 30 at a low speed of 850 rpm. However, the rotation of 1500 rpm and 2000 rpm will produce the same pressure, as well as at 2500 rpm with using SAE 30 and SAE 40.
The influence of shooting conditions during shot peening of stainless steel on surface roughness
Authors: Mukhsen M. Iqbal , Nur Rusdi , AF Yusuf M. Alif , Rakka Christo
Published: August 2020

Stainless steel AISI 316L is a suitable material used for orthopedic purposes. In order to improve the hardness of stainless steel, the heat-treatment process cannot be done, but with a shot peening process. This study aims to determine the roughness of the workpiece surface and investigate the effect of shooting conditions (i.e., angle and time) on the surface roughness during shot peening of Stainless steel AISI 316L. The shooting parameters used are 2, 4, and 6 minute for the duration, and angle of 0°, 15°, 30° and 45°. The ball material is a type of steel with 0.6mm in diameter. The experimental results presented that the increased shooting time will result in lower surface roughness, and vice versa. Therefore, it can be concluded that the use of varying shooting conditions will greatly affect the quality of the surface produced but needs to be compared with other responses, namely hardness.
Computational studies of pressure distribution of flow through inline dimpled plate
Authors: Sukardin M Setiawan , Salam Nasaruddin , Tarakka Rustan , Haddade Jalaluddin , Ihsan Muhammad
Published: August 2020

Dimple plates are widely used for construction and vehicles, especially in car bodies, trains, and aircraft wings. The dimples surface helps to overcome turbulent airflow around vehicles, thereby delaying the separation point and producing fewer vertices and drag. This study aims to predict the pressure distribution occurring over the plate surface with the formation of inline dimple rows on the upper back end. The test is carried out with Computational Fluid Dynamic (CFD) FLUENT program. The test model has a dimension of 300 mm in length, 100 mm in width, and dimples ratio (DR) of 0.5. Dimples are arranged inline as much as 1 to 6 rows. Upstream velocities through dimple plates range from 10 m/s to 20 m/s. The results of the study show that the minimum pressure coefficient occurs at the top front of the plate due to the flow separation that occurs at the front end of the plate. At x/L=0.25 x/L=0.5 and x/L=0.75 (before the dimples formation), a flow pattern returns to normal, this can be seen from the distribution of the relative pressure coefficient that does not change. At the measurement point x/L=0.95 (after dimples formation), there is a decrease in the pressure coefficient. This decrease occurs due to changes in flow characteristics. The pressure coefficient does not change significantly in dimple variations of 2 to 4 rows. Meanwhile, the pressure coefficient decreases with the variation of the 5 and 6-row dimples.
Production capacity planning using RCCP method with CPOF approach: a case study in an automotive Industry
Authors: Aisyah Siti , Hardi Purba Humiras , Dewarani R F
Published: August 2020

The consumer motorcycle soaring demand cause automotive manufacturing has an obstacle in fulfilling them. The motorcycle manufacturing realizes that the soaring demand has a constraint in terms of production load or meet. The aim of this study was to conduct an RCCP analysis with the CPOF approach in the XYZ Company assembling line. The problem that occurred in the assembling line consists of 3 working groups, namely sub assy, mainline RH, and mainline LH. The solution to the problem in the assembling line is done by the Rough Cut Capacity Planning-RCCP method of Capacity Planning Using Overall Factor Approach-CPOF. Based on the result using the CPOF approach, the production load of each workgroup was calculated as follows: sub assy of 115,690 minutes, mainline RH of 186,000 minutes and mainline LH of 218,701 minutes. This result showed an overload capacity in the assembly line and led to a production loss of 868 units in January, 836 units in February, and 867 units in March. It is possible to solve this underload problem through overtime and work weekends.
Production capacity planning in motorcycle assembly line using CRP method at P T XYZ
Authors: Purba Humiras Hardi , Aisyah Siti , Dewarani R F
Published: August 2020

PT XYZ is an automotive manufacturing company that produces a motorcycle. In an effort to meet the needs of consumers precisely and quickly, PT XYZ deals with problems in terms of fulfilling the capacity in accordance with consumer demand. The problem of imbalanced production capacity occurred in assembly line 3 that produced motorcycle of FU types, consisting of 3 workgroups, namely sub assy, mainline RH, and mainline LH. The imbalance between the capacity and load was due to many work elements of an operator. Thus the load on each work in the three workgroups was greater than the available capacity. This problem was solved using the method of Capacity Requirement Planning/CRP. Based on the result using CRP, the production load of each workgroup was calculated as follows: sub assy of 115,690 minutes, mainline RH of 186,000 minutes and mainline LH of 218,701 minutes. This result showed an overload capacity in the assembly line and led to a production loss of 868 units in January, 836 units in February, and 867 units in March. It is possible to solve this under loading problem through overtime and work weekends.
The implementation of preventive maintenance using machine damage analysis: a case study of power plant machine
Authors: Islam Sri S , Lestari Tika , Fitriani Anisa , Wardani Dilla Ayu
Published: August 2020

Maintenance has an important role in supporting the manufacturing process. The irregular maintenance in the industry can cause downtime and discontinue the production process. The importance of maintenance can be seen in PT PLN Sektor Tello, one of the industries which supply the electricity in Makassar. Since the electricity contributes to the huge impact on the life’s sector, there should be preventive maintenance to all of the machine components in order to ensure that the components can run well and reduce the impact. To analyze the PT PLN Sektor Tello machine’s performance, the researchers use the Failure Mode and Effect Analysis (FMEA) to identify the type of failures and recommend the maintenance plan. The FMEA’s result will be used to calculate the RPN (Risk Priority Number) for each failure and provide the recommendations that will be conducted at maintenance when the RPN’s value is equal or more than 125. By using the FMEA, we found three types of machine failures, such as the component’s leakage, the machine’s knock, and the broken component.
Decision support system for selection of tourism in Tana Toraja using technique for order preference method by similarity to ideal solution (topsis)
Authors: Topadang Anton , Triyono Agus
Published: August 2020

Tana Toraja is one of the favorite tourist destinations in South Sulawesi. In Tana Toraja, there are many tourist sites that offer various advantages each. This can make tourists confused in determining the right tourist location to visit. Therefore we need a system that can provide the right information in determining the exact location of a tourist destination. This study aims to make it easy for prospective visitors to choose tourism objects in Tana Toraja that they wish. The method used in this study is the TOPSIS and fuzzy methods that can provide an alternative ranking of tourist attractions. The result of this Decision Support System is to produce recommendations for tourist attractions that can be visited by tourists.
Application of line balancing using the heuristic method to equalize the production line at PT.Bogatama Marinusa Makassar
Authors: Sawal Ahmad , Hamzah Ainun Jariah
Published: August 2020

PT. Bogatama Marinusa is one of the fishery industry sectors located in South Sulawesi that moves in shrimp processing and frosting as pioneer of fishery industry in southern Sulawesi. PT. Bogatama Marinusa certainly wants the planned production target to be achieved as expected, where every day the company processes raw materials with the capacity of approximately 575 kg for vannamei shrimp and 425 kg for black tiger shrimp. At deheading work station (shrimp head separation) and sortation area (sorting) materials buildup occurs in the production flow (bottle neck) which results an idle time to other work stations. With the existence of these problems, it is necessary to do production line balancing in order to minimize idle time and be able to balance the production lines so that the works carried out effectively and efficiently. The method used for overcoming the production line imbalance is by applying line balancing, namely the heuristic method, which is calculation using Regional Approach (RA) and Ranked Positional Weight (RPW) methods. Line efficiency (LE) increased by 83.33%, smoothing index (SI) decreased by 160.90, balance delay (BD) decreased by 16.66%, and idle time (IT) decreased by 264 minutes, and production capacity could be increase to 1,022 kg means that the results are far better than the current conditions.
Flood handling with priority scale determination in Samarinda Seberang from East Kalimantan Province Indonesia
Authors: Banjarsanti SSN. , Kukuh P. , Margaritifera Theta
Published: August 2020

Handling of flooding caused by changes in land use often causes changes and problems in the magnitude of runoff coefficient, discharge, water level, and drainage channel dimensions, as happened in Samarinda Seberang. The purpose of this study was to plan a drainage channel according to the priority scale using the Rational Modification Method as a Hydrological Analysis and Manning as a Hydraulics Analysis. Handling method is carried out in the form of structuring and planning the drainage system according to priority scale based on inundation parameters, economic studies, social and transportation disturbances, loss of housing areas, and property rights. The higher the criteria for handling the area is a priority. The results showed that the highest priority scale (610) was obtained on Cipto Mangunkusumo street, and the lowest priority scale (220) was at Bung Tomo street and Hasanuddin street. Cipto Mangunkusumo street as the highest priority scale will be planned for the first priority drainage channel with a design flood discharge in the 10 year return period (Q) 7.79 m3 / sec, the drainage channel dimension consists of the basic width of the channel (b) 0.77 m ∼ 0.80 m, channel peak width (T) 3.30 m, channel depth (h) 1.925 m, watch height (f) 0.6 m, total depth 2.52 m, and slope of channel wall (m) 1: 1).