bluuebunny/crossref_metadata_2025 huggingface dataset:
Electronic structures of vacancies in Co3Sn2S2
*
Authors: Gao Yuxiang , Jin Xin , Gao Yixuan , Zhang Yu-Yang , Du Shixuan
Published: April 2021

Co3Sn2S2 has attracted a lot of attention for its multiple novel physical properties, including topological nontrivial surface states, anomalous Hall effect, and anomalous Nernst effect. Vacancies, which play important roles in functional materials, have attracted increasing research attention. In this paper, by using density functional theory calculations, we first obtain band structures and magnetic moments of Co3Sn2S2 with exchange-correlation functionals at different levels. It is found that the generalized gradient approximation gives the positions of Weyl points consistent with experiments in bulk Co3Sn2S2. We then investigate the electronic structures of defects on surfaces with S and Sn terminations which have been observed in experiments. The results show that the single sulfur vacancy on the S-terminated surface introduces localized bond states inside the bandgap near the Fermi level. For di- and tri-sulfur vacancies, the localized defect states hybridize with neighboring ones, forming bonding states as well as anti-bonding states. The Sn vacancy on the Sn-terminated surface also introduces localized bond states, which are merged with the valence bands. These results provide a reference for future experimental investigations of vacancies in Co3Sn2S2.
First-principles study of electronic structure and magnetic properties of Sr3Fe2O5 oxide*
Authors: Rahman Mavlanjan , He Jiuyang
Published: April 2021

We investigate the electronic structure and magnetic properties of layered compound Sr3Fe2O5 based on first-principles calculations in the framework of density functional theory with GGA+U method. Under high pressure, the ladder-type layered structure of Sr3Fe2O5 is transformed into the infinite layered structure accompanied by a transition from G-type anti-ferromagnetic (AFM) insulator to ferromagnetic (FM) metal and a spin transition from S = 2 to S = 1. We reproduce these transformations in our calculations and give a clear physical interpretation.
Adaptive synchronization of a class of fractional-order complex-valued chaotic neural network with time-delay*
Authors: Li Mei , Zhang Ruo-Xun , Yang Shi-Ping
Published: April 2021

This paper is concerned with the adaptive synchronization of fractional-order complex-valued chaotic neural networks (FOCVCNNs) with time-delay. The chaotic behaviors of a class of fractional-order complex-valued neural network are investigated. Meanwhile, based on the complex-valued inequalities of fractional-order derivatives and the stability theory of fractional-order complex-valued systems, a new adaptive controller and new complex-valued update laws are proposed to construct a synchronization control model for fractional-order complex-valued chaotic neural networks. Finally, the numerical simulation results are presented to illustrate the effectiveness of the developed synchronization scheme.
Probability density and oscillating period of magnetopolaron in parabolic quantum dot in the presence of Rashba effect and temperature*
Authors: Chen Ying-Jie , Shao Feng-Lan
Published: April 2021

We study the property of magnetopolaron in a parabolic quantum dot under the Rashba spin–orbit interaction (RSOI) by adopting an unitary transformation of Lee–Low–Pines type and the variational method of Pekar type with and without considering the temperature. The temporal spatial distribution of the probability density and the relationships of the oscillating period with the RSOI constant, confinement constant, electron–phonon coupling strength, phonon wave vector and temperature are discussed. The results show that the probability density of the magnetopolaron in the superposition of the ground and first excited state takes periodic oscillation (T
0/period) in the presence or absence of temperature. Because of the RSOI, the oscillating period is divided into different branches. Also, the results indicate that the oscillating period increases (decreases) when the RSOI constant, electron-phonon coupling strength and phonon wave vector (the confinement constant) increase in a proper temperature, and the temperature plays a significant role in determining the properties of the polaron.
Real-time, precise, rapid and objective visual acuity assessment by self-adaptive step SSVEPs
Authors: Zheng Xiaowei , Xu Guanghua , Du Chenghang , Yan Wenqiang , Tian Peiyuan , Zhang Kai , Liang Renghao , Han Chengcheng , Zhang Sicong
Published: April 2021

Objective. This study aimed to explore an online, real-time, and precise method to assess steady-state visual evoked potential (SSVEP)-based visual acuity more rapidly and objectively with self-adaptive spatial frequency steps. Approach. Taking the vertical sinusoidal reversal gratings with different spatial frequencies and temporal frequencies as the visual stimuli, according to the psychometric function for visual acuity assessment, a self-adaptive procedure, the best parameter estimation by sequential testing algorithm, was used to calculate the spatial frequency sequence based on all the previous spatial frequencies and their significance of the SSVEP response. Simultaneously, the canonical correlation analysis (CCA) method with a signal-to-noise ratio (SNR) significance detection criterion was used to judge the significance of the SSVEP response. Main results. After 18 iterative trails, the spatial frequency to be presented converged to a value, which was exactly defined as the SSVEP visual acuity threshold. Our results indicated that this SSVEP acuity had a good agreement and correlation with subjective Freiburg Visual Acuity and Contrast Test acuity, and the test–retest repeatability was also good. Significance. The self-adaptive step SSVEP procedure combined with the CCA method and SNR significance detection criterion appears to be an alternative method in the real-time SSVEP acuity test to obtain objective visual acuity more rapidly and precisely.
How to build a fast and accurate code-modulated brain-computer interface
Authors: Ramírez Torres Juan Antonio , Daly Ian
Published: April 2021

Objective. In the last decade, the advent of code-modulated brain-computer interfaces (BCIs) has allowed the implementation of systems with high information transfer rates (ITRs) and increased the possible practicality of such interfaces. In this paper, we evaluate the effect of different numbers of targets in the stimulus display, modulation sequences generators, and signal processing algorithms on the accuracy and ITR of code-modulated BCIs. Approach. We use both real and simulated electroencephalographic (EEG) data, to evaluate these parameters and methods. Then, we compared numerous different setups to assess their performance and identify the best configurations. We also evaluated the dependability of our simulated evaluation approach. Main results. Our results show that Golay, almost perfect, and deBruijn sequence-based visual stimulus modulations provide the best results, significantly outperforming the commonly used m-sequences in all cases. We conclude that artificial neural network processing algorithms offer the best processing pipeline for this type of BCI, achieving a maximum classification accuracy of 94.7% on real EEG data while obtaining a maximum ITR of 127.2 bits min−1 in a simulated 64-target system. Significance. We used a simulated framework that demonstrated previously unattainable flexibility and convenience while staying reasonably realistic. Furthermore, our findings suggest several new considerations which can be used to guide further code-based BCI development.
Preliminary spectral matching analysis of RDE site at Serpong Indonesia
Authors: Yuliastuti  , Hakim E E Al , Wicaksono A B , Iswanto E R , Syaeful H , Sunarko
Published: April 2021

In concurrent with the plan to build small experimental power reactor at Serpong site, site specific response spectra evaluation is required to ensure the reactor safety. Site response spectra involved the spectral matching analysis which incorporates the seismic characteristics of the site and the design spectra. This paper presented the preliminary spectral matching analysis of selected natural earthquake records by comparing Al Atik & Abrahamson (2006) algorithm and Hancock et. al (2010) algorithm. The natural earthquake records were selected based on their similarity of their characteristics such as magnitude, distance resulting from deagregation analysis and site-specific conditions. Two subset periods were employed in the spectral matching analysis. Fourier spectrum and wave envelope analysis showed that both algorithms have maintained the original non-stationary characteristics. PGA, PGV and PGD values resulting from spectral matching have significant changes from the original as an implication of accelerogram amplitude scaling. From the spectral matching analysis, KAU083 record resulting from Hancock et. al (2006) algorithm has yielded the best matched to the target spectra compared to other selected records.
Numerical simulation and analysis of nominal wake of displacement ship
Authors: Li Xiang , Dong Jinshuang , Sun Shuai
Published: April 2021

In order to analyze the performance of ship resistance and nominal wake of container ship and bulk carrier, the method of CFD was used to compare the influence factors such as the distribution pattern of grids and turbulence models, and the calculation results were compared with experimental values. The predicted results show that the ship resistance calculated by the model of Volume of Fluid achieves a good agreement with experimental data. An optimal scheme for computing the nominal wake was got by analyzing the results of three grid schemes and two turbulence models. The container ship’s axial nominal wake, tangential nominal wake and radial wake has the same variation trend with the experimental data, so it validates the feasibility of this method set in this paper. Thenominal wake of a bulk carrier took as an example was computed and the “hooked” wake was also got very well. At the same time, the cause of the “hooked” wake was got a good analysis.
The Effect Of Adhesive Variations (Starch, Liquid Smoke, and Used Oil), And The Form Of Rice Husk Briquette (Cylinder and Block) On The Performance Of The Gasification TLUD Method
Authors: Wijianto  , Sarjito  , Aklis Nur , Subroto  , Sulistyanto Amin
Published: April 2021

This research aimed to determine the effect of the adhesive types on rice husk briquettes in the TLUD gasification process. The types of adhesive used are starch, tar, and used oil. Rice husk briquettes have varied in two forms, namely cylindrical and block shapes. Each variation has a diameter of 1 inch and a side of 1 inch as well. Rice husk in uniform meshing with 20 mesh size. The Gasification process uses rice husk briquette as fuel. The next step is to insert 3 kg of briquettes into the gasification cylinder. Then ignited to start the gasification process. The type of gasification furnace used is the TLUD type. That is an updraft type gasification with initial ignition on the upper surface of the briquette fuel. Data collection was carried out to determine how much the sufficient flame temperature was and how long the gasification process’s adequate flame time took place and determine the briquettes’ quality by testing the water boiling test. These test results show that rice husk briquettes with used oil adhesive variations are better than other adhesive variations, reach an average temperature of 755°C, and boil 2 liters of water in 6 minutes.
Analytical Hierarchy Process (AHP) to Determine the Sustainable Drainage System Used for Flood Management in Central Karanganyar Regency
Authors: Kurnianingsih O , Solikin Mochamad , Pudyastuti P , Sunarjono S , Hidayati N
Published: April 2021

A sustainable drainage system is one of the right methods in dealing with floods in cities, including in Karanganyar. The parameters of technology selection problems planned with the Analytic Hierarchy Process (AHP) are technical, economic, environmental, social/cultural, and technology: infiltration wells with drainage channels, rainwater harvesting with drainage channels, and dry swale. Rainfall data is used in this research. The area used is planning, budget planning, and AHP method steps with hierarchical compilation, pairwise comparisons, priority values, testing consistency, and data obtained from technology selection questionnaires filled with related institutions. The most influential criteria in the choice drainage system technology are environmental criteria 49%, technical 33%, economy 12%, and social/cultural 5%. The priority technology is rainwater harvesting with drainage channels with a percentage of 37.3%, infiltration wells with drainage channels 35.2%, and dry swale 27.4%.
Terraced Wetland Construction of Liquid Waste Pollution Countermeasures from Tofu Industry (Case Study of Tofu Industry in Mojosongo, Surakarta)
Authors: Karnanta Sunandar Priya , Solikin Mochamad , Purnama Herry
Published: April 2021

Tofu is a food that every level of society liked because of its low price and many nutrient contents. Tofu making uses a lot of water for sorting, immersion, boiling, and filtering to produce enough liquid tofu waste. The problem that most rises related to the tofu industry is the problem of waste processing. If the tofu waste is disposed of directly into the river, it will affect the life of biota and pollute the environment. Therefore facility is needed for wastewater treatment that can be used continuously with a wetland construction system. The A filter composition consists of sand, charcoal, and zeolite. The B composition consists of soil, palm fiber, sand, charcoal, and zeolite with cattail plants (Thypa latifolia). C composition consists of soil, palm fiber, sand, charcoal, and zeolite with cattail plant (Thypa latifolia) and Phragmites australis. The three compositions are then analyzed in filtering the tofu industrial wastewater. The best result of tofu liquid waste processing is using the C wetland composition construction; pH with a value of 6.7 BOD with a value of 146mg/L, COD 338mg/L, TSS 123mg/L.
Dynamic Model and Equilibrium Stability of an Inverted Double Pendulum System
Authors: Susanto Erwin , Yuwono Sigit
Published: April 2021

Most inverted pendulum types, such as single or double pendulums, translational or rotational, are underactuated, nonlinear, and unstable. To handle this inverted pendulum, much effort has to do, especially in stabilization aspects. An appropriate control strategy based on suitable modeling is the key to stabilization’s handling. Modeling and stabilizing an inverted double pendulum need more complex efforts than those of a single type. The obtained model is indispensable for control design in future works, and the success of the method depends on the accuracy of the developed model. The result showed that the dynamic model is fit enough, and the eigenvalue of the system is unstable, as predicted earlier.
Shear Strength Evaluation of Silt-Clay Soil Under Uni-Axial Compression
Authors: Listyawan Anto Budi , Wiqoyah Qunik , Sukmawati Titis Asih
Published: April 2021

Effect of different moisture content and applied pressure to soil shear strength parameters are evaluated. Silt-Clay soil from Ngemplak, Kalikotes, Klaten Regency becomes the subject of the experiment. The research was conducted using a simulation in the laboratory to determine the relationship between water content and soil pressure. The expected values are the pressure that arises and the shear strength of the soil when using four water constructions of 20%, 25%, 30%, and 35%. For each variation of moisture content, three different pressure in the form of uni-axial compression that considered based on the different energy given by equipment used to do compaction will affect the soil density. The applied pressure used is 1.5 kN, 2.5 kN, and 3.5 kN. The result showed that moisture content having a great impact on soil shear strength parameter. The cohesion of soil decreases due to an increase in water content. The friction angle works in linear conditions with moisture content but decreases at the value of 35% water content. The best-fitted distribution for the relationship between soil shear strength and moisture content is polynomial order two. Follow the equation for 1.5 kN applied pressure is y = -0.0036x
2 + 0.2236x - 2.4898, for 2.5 kN applied pressure the equation is y = -0.0025x
2 + 0.1545x-1.3383, and for 3.k kN applied pressure the equation is y = -0.0022x
2 + 0.1357x - 1.0344.
Characterization of Polypropylene Sheet Friction Stir Spot Welded Joint
Authors: Nugroho Aris Widyo , Dadang Dika O. H. , Budiyantoro Cahyo , Himarosa Rela Adi
Published: April 2021

A study to determine the effect of rotational speed and geometric shape of a tool on the mechanical properties of polypropylene joint using the FSSW technique has been carried out. A polypropylene sheet was cut into pieces with a dimension of 150 x 30 x 5 mm. A medium carbon steel bar was machined to fabricate welding tools. Two types of devices with shoulder angles of 0° and 5° were prepared, while the other parametric geometries were the same. While the friction stir spot welding (FSSW) process has been carried out at variations of rotational speeds of 985, 1660, and 2350 rpm, the other welding process parameters, such as tool plunge rate, dwell time, and delay time, were considered constant. The tensile shear load capacity, macrostructure, hardness, and failure mode of the joint results were then evaluated. The results revealed that using a pin tool with a shoulder angle of 5° achieved a maximum tensile shear load capacity at a rotational speed of 2350 rpm with a result of 2253 N due to its wider nugget area. The load capacity increased with the increase of rotational speed. A pin tool angle of 15° with a shoulder angle of 5° may be suggested for the tool’s chosen geometry.
Redesign and Remanufacturing the Shot Peening Machine: Model and Experiment
Authors: Nari Henny Pasandang , Sirman Mahadir , Nur Rusdi , Iqbal Mukhsen M.
Published: April 2021

Stainless steel is a material that is corrosion resistant and can be used as an implant material (type 316L). Cold treatment can only increase stainless steel’s hardness, one of which is the shot peening process. This paper aims to remanufacture the shot peening machine for laboratory-scale testing purposes. The methodology used in designing the device, making all the necessary components, assembling it, and testing the shot peening machine with several specified parameters. The conclusion that can be obtained is the shot peening machine has been well designed and remanufactured and has appropriately functioned based on the performance that has been shown in the testing of stainless steel 316L.
Analysis of Walkability Index and Handling of Pedestrian Facilities of Slamet Riyadi Street, Surakarta
Authors: Erlangga Dwiky , Handayani Dewi , Syafi’i
Published: April 2021

Slamet Riyadi Street is the main street in Surakarta. It is located in the city center, which connects the activity center or CBD. The rapid development of activities needs to be balanced with adequate facilities and infrastructure related to the existing pedestrian paths’ maintenance and rehabilitation. This research uses the walkability index method to compares the walking comfort index assessment based on the Global Walkability Index variables and SE PUPR 02/SE/M/2018 variables. The findings showed a very significant difference between the two. GWI got a score of 56.2, while SE PUPR got a score of 49.4. Demonstrating the effectiveness of GWI assessment when used to assess the pedestrian paths in Indonesia was poor. Then, determining several recommendations for handling facilities with pedestrian perceptions based on SE PUPR variables uses the Likert scale method. The result of the analysis included the facilities related to conflicts on the pedestrian paths and the behavior of the motor vehicle drivers at the crossing locations on the south and north sides of the pedestrian paths, as well as other facilities on the north side concerning the security from crime, complete facilities, disability infrastructure, maintenance and cleanliness, and pedestrian obstacles.
Chlorophyll Extraction Methods Review and Chlorophyll Stability of Katuk Leaves (Sauropus androgynous)
Authors: Kwartiningsih Endang , Ramadhani Aida Nur , Putri Nadia Gusti Ami , Damara Vicky Clarissa Jennie
Published: April 2021

Chlorophyll is one of the most used coloring materials derived from green leaves and other parts of almost all green plants. It contains several components that are beneficial to health: vitamins, antioxidants, antibacterial, anti-inflammatory; hence, chlorophyll is a nutraceutical. Chlorophyll has been developed by extracting green plants, for instance, katuk leaves (Sauropus androgynous). A review of various chlorophyll extraction methods from natural ingredients was done to obtain the most suitable katuk leaves. Preliminary experiments had been carried out to develop the chlorophyll stability of katuk leaves on the influence of temperature, pH, and storage time. The chlorophyll content of katuk leaves decreased at high temperatures. Extraction using supercritical/subcritical CO2can extract components selectively so that it is suitable for extraction applications for products that are not heat resistant. Meanwhile, carbon dioxide (CO2) as a supercritical/subcritical solvent has several advantages, including producing an inert gas that is non-toxic, non-flammable, and cheap. Under normal gas conditions, it is straightforward to separate CO2and dissolved components without heating and producing extracts free of solvents. The most suitable chlorophyll extraction method of katuk leaves was supercritical/subcritical CO2extraction because it could prevent chlorophyll degradation.
A Single Batch Processor Scheduling Model with Additional Setup Times to Minimize Total Actual Flowtime of Parts of Multiple Items
Authors: Hidayat Nita P A , Aribowo Wisnu , Halim Abdul Hakim
Published: April 2021

The problem investigated in this paper is arranging parts for the etching process on a single batch processor in a craft company. The company produces several different metal plate types, and each type requires another processing time and setup time. The machine also needs additional setup after processing several production batches. All metal plates that have been processed will be delivered simultaneously at the expected due date. The objective is to minimize the total actual flowtime of parts of multiple items through the shop. The problem is formulated as a mixed-integer nonlinear programming model. A simple numerical example is provided to demonstrate the execution of the mathematical model to a hypothetical question.
Encapsulation of oryzanol-rich rice bran oil using carrageenan
Authors: Fadilah  , Distantina Sperisa , Susanti Ari Diana , Damara Liginia Gustin Ayu , Mawarni Grace Hana
Published: April 2021

Experiments have been carried out to encapsulate rice bran oil using carrageenan. Two methods have been tried. In the first method, the chitosan-carrageenan polymer solution was dropped into the NaOH-ethanolate solution. The solid formed is filtered and immersed in a 6% glutaraldehyde solution, then filtered and dried. The resulting solid is clustered and not form granules. In the second method, a solution called A in the form of oil emulsion in carrageenan solution is dropped into chitosan solution and then heated to 70°C. Glutaraldehyde is added to the solution, and the cross-linking process is continued for 3 hours. The solid is filtered and washed with water then with n-hexane. The resulting solid is washed with ethanol and then dried. Experiments result with variation in the amount of carrageenan showed the best results when using 0.3 g carrageenan and 0.5 mL of oil.
Tensile Strength and Elongation Testing for Starch-Based Bioplastics using Melt Intercalation Method: A Review
Authors: Gabriel Azmi Alvian , Solikhah Anggita Fitri , Rahmawati Alifia Yuanika
Published: April 2021

Plastics were commonly used as packaging materials for primary, secondary, and tertiary needs. However, the continuous use of plastic was inadequate for the environment. The research that was developing to address the use of conventional plastics is bioplastics. Bioplastics undergo faster degradation but had low mechanical strength and were hydrophilic. One of the main ingredients of bioplastics was starch. This study aimed to examine the effect of using starch-based materials on the quality parameters of bioplastic tensile strength and elongation quality. The tensile strength and elongation values of bioplastic from various treatments showed a relatively large range of results. Glycerol was the most widely used plasticizer because Glycerol has the best interaction ability compared to other plasticizers when combined with starches with different characters, either by adding various types of fillers or without adding fillers. The types of fillers that were commonly used are chitosan, clay, and ZnO. The use of plasticizers and fillers gives an opposite contribution to the bioplastic quality of tensile strength and Elongation.
Simulation of Natural Daylighting Optimization in College Library
Authors: Dianagri Audrey Tara , Sari Wulani Enggar , Harsitanto Bangun I R
Published: April 2021

In a library’s reading area, sufficient light exposure is needed to see objects around the users’ field of vision for their activities. Regarding the case study, as an equatorial region, Indonesia also has the advantage of getting a continuous high radiation climate throughout the year. Therefore, buildings around the area need to optimize this benefit to achieve optimal energy efficiency. Meanwhile, according to the national standards of SNI 6197-2011, the simulation of the existing reading area in PGRI University’s Library has not achieved the optimized daylighting performance. This research aims to improve the lack of daylighting performance, using DIALux EVO simulations as the primary method to analyze the library’s existing condition and to evaluate each design proposal for retrofitting. The study then found that among all other options, the recommendation to add five more window openings on the north walls, setting up 0.8-meter width light shelves, and reducing the window overhang length to 0.25 meter is the most effective ways to optimize the daylighting performance in the library.
Sensitivity analysis of a novel geothermal multigeneration system with liquefied natural gas, proton exchange membrane, absorption refrigeration system, and water desalination
Authors: Dikaimana Yophie , Nasruddin  , Ismoyo Budi
Published: April 2021

Renewable energy, such as geothermal, is very effective in reducing the effects of greenhouse gas emissions. Therefore, a geothermal-based multi-generation system can produce commodities for power, hydrogen, liquefied natural gas, cold energy recovery, cooling, and water desalination. Power the multigeneration, energy, and exergy analyses are conducted using Engineering Equation Solver (EES) software. Constraints used are a steam fraction, geothermal temperatures, and MER (mass extraction ratio). Sensitivity analysis is given to the parameters of exergy efficiency, net output power, a mass flow rate of natural gas, a mass flow rate of hydrogen, a mass flow rate of pure water, and the coefficient of performance of the absorption refrigeration system. Thermal efficiency is 27.2%. Exergy efficiency is 35.89%. The net power output from turbine 1 is 997.8 kW, from turbine 2 is 343.2 kW. The hydrogen mass flow rate is 0.0008 kg/s. The natural gas mass flow rate that can be used is 1.252 kg/s. The coefficient of performance (COP) of the absorption refrigeration system (ARS) is 0.8876, and the mass flow rate of pure water of the water desalination system is 0.3914 kg/s.
Evaluation of Anode Composition in Lithium-Ion Batteries
Authors: Rachmanto Moch Khabibul Adi , Wibowo Liliana Triatmajaning , Paramitha Tika , Purwanto Agus
Published: April 2021

A lithium-ion battery is a rechargeable battery with excellent energy, high power, high theoretical capacity, economics, reasonable cycle rate, good stability, high-temperature resistance, and environmentally friendly. An anode is one of the main components of a lithium-ion battery. The most frequently used as an anode material is graphite. Graphite has good structure stability, excellent electrical conductivity, good cycle life and economics, high intercalation-deintercalation, high voltage, and energy efficiency. Another material that can be used as the anode component is SiO2. In this study, we evaluate the anode composition with the dependent variables of active material and binder. Moreover, the structures of samples were characterized by X-Ray diffraction measurement, and the electrochemical performances were tested by galvanostatic charge-discharge. The anode material was applied directly in a 18650 cylindrical cell and graphite with a mass composition of 90% exhibit the best performance with a specific discharge capacity of 367.44 mAh/g (at 0,1C) and coulombic efficiency of 92%.
Implementation of User-Centered Design (UCD) Method in Product Development of Traveling Wheelchair
Authors: Puspitasari Nia Budi , Putra Ridwan Permana , Rusnaldy  , Ismail Rifky , Prastawa Heru
Published: April 2021

Persons with disabilities often difficulties when traveling and mobility in daily activities, especially with movement disorders. Many tools have been developed for people with disabilities to support mobility. One of them is a traveling wheelchair. Based on preliminary studies, it is known that the dimensions of traveling wheelchairs tend to be smaller than wheelchairs in general and have limited features that affect the comfort of its users. This study tries to evaluate a traveling wheelchair using the user-centered design (UCD) method and usability testing and developing this product. The standard UCD method used is based on ISO 9241-210, which focuses on users’ needs and interests by applying ergonomic criteria and knowledge of usability techniques. The evaluation results show that the overall usability level of the wheelchair product tested has excellent standards with usability values ranging from 89.12%-94.56%. However, there are still several problems, especially in the usability satisfaction criteria. Based on the evaluation results and the user’s thinking aloud, the development of this traveling wheelchair product was carried out. Development is based on several parameters such as stability, wheelchair dimensions, seat, postural support, and adjustable and ergonomic factors.
Multiobjective optimization of synechocytis culture in flat-plate photobioreactor toward optimal growth and exergy
Authors: Nastiti Kania Dyah , Rahman Arif , Nasruddin
Published: April 2021

Many researchers are analyzing microalgae as a fuel source due to their high potential. Since microalgae are grown on a narrow area of land and less water, microalgae can contain high lipids. Carbon dioxide, water, inorganic salts, temperature and degree of acidity (pH), and light intensity in photobioreactors affect microalgae growth. Microalgae Synechocystis cultivated in BG-11 medium on closed PBRs with an addition of 10 mM NaHCO3. Culture medium illuminated at one side with Orange-red LED (636 nm) at light intensities of 50, 200, 300, 500, 800, 950, and 1,460 µmol photon/m2.s with light intensity adjustment every 24 hours. Optical density and exergy destruction also optimize for artificial neural network training and Multiobjective Genetic Algorithms. The optimum value from the TOPSIS approach is the OD 12.957 OD730 and 8660.35 kJ exergy destruction. The optimum condition is derived from the optimum value. The light intensity of 71 µmol photon/m2s and the dry cell weight of 0.119 g/OD730L are ideal conditions for optimal microalgae development.
Cyclic Behaviour of Palu Sandy Soils in Cyclic Simple Shear Test
Authors: Ramdhiani E , Prakoso W A
Published: April 2021

A 7.5-moment magnitude earthquake hit Palu, Central Sulawesi, Indonesia, in September 2018. This earthquake caused many damages and casualties, including tsunami and liquefaction. Following these events, Palu sand’s cyclic properties were investigated under cyclic simple shear testing conditions, which could convincingly portray the real seismic ground shaking under repeated shear force. All the tests were performed under the frequency of 1.0Hz with varied relative densities and cyclic stress ratio (CSR). The results show that grain size distribution plays a significant role in liquefaction resistance of sandy soils tested-the soils tested under higher CSR need fewer cycles to liquefy. Furthermore, soils which in loose conditions tend to have lower liquefaction resistance.
Design analysis of vibrational input to torque energy system
Authors: Triono A , Fitoyo A , Junus S
Published: April 2021

The development of digital technology in the Industrial Age 4.0 focuses on the application of the Internet of Things (IoT), Virtual Reality (VR) and Augmented Reality (AR). IoT as one of the main topics for technological advancement, which is useful for improving information and communication that is developing in the fields of manufacturing, infrastructure, business, economy etc. The development in the field of material technology can make small materials where the energy requirement to generate a device only requires a millivolt range of power, so by using energy from the surrounding environment which is converted into electrical energy, a device design for energy harvesting is required. The purpose of this research is to design a device that is sourced from various vibrations and converted into electrical energy. The concept of designing a vibration conversion mechanism into electric energy is by combining and optimizing the design of several existing tools (technologies). This research was tested experimentally by utilizing braking force. Tests are carried out using a data logger for further processing. From the results of the braking test, it is able to produce a maximum voltage of 0.9 V with a braking force of 34.72 N.
Comparison of Battery Models for Battery Energy Storage System Development
Authors: Perinov  , Garniwa Iwa , Hudaya Chairul , Sudiarto Budi
Published: April 2021

Battery Energy Storage System (BESS) can be utilized in various ways to improve the reliability, durability, and efficiency of grid operations. With the advancement of battery technology and rapid cost reduction, BESS has become very promising. An accurate BESS model in simulation platform is very important to design an efficient BESS-connected powered system. Battery as one of the main components that govern BESS perfomance need to be modeled. There are many battery models that has been developed. In this paper, some of battery models will be studied and the comparison of different battery models is also presented.
Turbidity Monitoring of Freshwater Using Internet of Things Platform
Authors: Supriyono Heru , Hibatullah Asmanditya , Harismah Kun
Published: April 2021

This article discusses the development of the monitoring system of fresh water turbidity level. The objective of this article is to monitor the turbidity level of the water continuously and remotely. The monitoring system was developed by using a turbidity sensor and ESP32. The measured turbidity level in Nephelometric Turbidity Units (NTU) was then sent to the internet of things platform namely ThingSpeak cloud computing platform by using wireless fidelity (wifi) networks so that it could be accessed by using Android smartphone or computer. The obtained monitoring system was tested on the laboratory scale fresh water body placed in the acrylic box with dimensions of 25cm × 19cm × 31cm. The test results showed that the monitoring system was able to monitor the turbidity level constantly on various conditions, i.e. fresh water without any substance addition and when sedimentation substances were gradually added into the water body. The output of turbidity sensor (in volt) was linear with the obtained NTU level. In the future, the monitoring system should be enhanced for actual condition of fresh water especially for sources drinking water.
Optimum compressive strength of geopolymer concrete in variations comparison of ingredients and mixing time
Authors: Trinugroho Suhendro , Ningrum Rina Septia
Published: April 2021

Concrete has been criticized more recently because of the greenhouse gas (carbon dioxide) emissions it produces in the cement portland production process. With these considerations, a new concrete binder called geopolymer concrete was developed. One of the materials used in the manufacture of geopolymer concrete is fly ash. Using fly ash as a substitute for cement is considered to be able to preserve the environment and reduce development costs. In this study, the specimen used was cylindrical, with a diameter of 15 cm and a height of 30 cm. The concrete compressive strength test was carried out at the age of 28 days. Variations in concrete testing include: Test the strength of the concrete on the variation of the binder ratio: coarse aggregate of 20%:80%, 25%:75%, 30%:70%, 35%:75% 40%:60% and the variation of stirring time 5 minutes, 7.5 minutes, 10 minutes, 15 minutes. From the test results, it can be concluded that the optimum mixing time for the concrete mix is 7.5 minutes. If it is less than 7.5 minutes it will result in less than maximum binder binding power. And if the mixing time is more than 7.5 minutes it will decrease the adhesion of the binder. Regarding the variation of concrete on the amount of use of fly ash, it can be concluded that the higher the fly ash content, there is a tendency for low compressive strength, this is due to the influence of the water content used in the mixture is obtained based on the weight of fly ash in each variation. So if the weight of fly ash is higher, the water demand will also be higher and it will result in too dilute fresh concrete, so that the compressive strength of the concrete decreases.
Solar Photovoltaic Application for Contributing Power Supply of Community Clean Water Provider
Authors: Ulinuha Agus , Prabowo Satrio Nur
Published: April 2021

The need of clean water for human daily life is about crucial. Due to the inadequate capability of government water supply company, it is becoming common for a community to establish their own water supply system. This includes a deep well, high water reservoir, and submersible pump. The pump is normally supplied with power from electricity grid. The extensive availability of sunlight may be used to generate electric power using Solar Photovoltaic (PV) panels for supplying power for the pump. This paper presents the application of Solar PV panels to generate power that contributes power for the pump at the system of clean water provider. A 1000-WP solar panels system is employed to generate the voltage and a 60-A MPPT is used to regulate the voltage for supplying 2 x 150-Ah Li-ion battery. A 3000-W inverter is used to provide AC power for 3-hp 220-V pump. Considering the capacity of Solar PV panels and the continued availability of sunlight, the hybrid supply for the pump is established. This integrates the supply from solar PV and utility grid controlled with Automatic Transfer Switch (ATS). This determines the power supply for the pump either from Solar PV or electricity grid. This system is implemented in the community water supply at Sidomulyo, Krikilan, Sragen. The hybrid strategy enables solar PV to contribute supplying power for the pump and reduce the need of power from utility.
The damage trees study for a good and save roadside greenery planning in Surakarta City, Central Java
Authors: Indrawati I. , Nurhasan N.
Published: April 2021

Purpose: This research question is ‘how to plan a good and save the road side greenery in Surakarta?’ The research objectives are: Identification of the trees characteristics (type and size); Identification level of the health trees, and Trees location. Methodology: This research used categorized methods by health of tree, that is: health, little damage, moderate damage and heavy damage. The research location at Slamet Riyadi street, Jenderal Sudirman street and Urip Sumohardjo street at Surakarta City. Results: This research has built a Tree Inventory Application, named SIPPOHON. Through SIPPOHON trees can be inventoried by the name, type and characteristics. Tree location is integrated in a global positioning system (GPS); The Polyalthia longifolia, Mangifera kemanga, Diospyros blancoi have a strong endurance tree; Pterocarpus indicus, Erythrvna, Manilkara kauki, Langerstroemia and Casuarina tend to be damaged or unhealth; Some forms of tree damage are caused by: hole and trunks hollow; mechanical damage (scratches and cuts at the tree until the cortex); the brittle stems caused by pest attacks; swelling of the stem; the dead of partial canopy; trees tilted into the electricity grid; and roots appear to the surface of land. Applications: The result of the research are an SIPPOHON application to manage the green roadside, especially: Treatment of pest are needed to prevent the spread of disease and Routine maintenance and monitor the tree condition.
Flood Hazard Assessment with High Spatial Resolution Under Climate Change Scenario
Authors: Ikhzan Jazaul , Apip  , Fakhrudin M , Subehi Luki , Yamamoto Kodai
Published: April 2021

One of the important components in flood disaster risk reduction is the availability of spatial information on flood risk that include: (1) flood hazard component such as flood discharge ( q), flood depth (h), flood extent (A ), and flood duration (t), and (2) the loss value due to flood which could be quantified in the form of damage costs (θ). Change in the value of risk f (h, A, t, θ) was hypothesized to be sensitive to climate change and other environmental factors that exist at a river basin area. Therefore, it is quite important to control the flood disaster risk as a part of adaptation programs to the climate change impacts and to deal with the increasing pressure due to anthropogenic activities. Additionally, to support the action plan and to increase the understanding and awareness related to the flood disaster mitigation, spatial information on flood risk which having high resolution and precision is required. This study aimed to quantify the spatial information of flood hazard with high spatial resolution. Two Dimensional (2-D) flood-modelling system (e.g., rainfall-runoff-inundation) at the river basin scale has been used as the main method in quantifying the flood hazard dimension. Furthermore, this study was focused in the Batanghari River basin, Sumatra and 13 river catchments flow out through the Jakarta Capital City of Indonesia. Obtained hazard information forms the basis for long term management decisions on improving operational flood risk management, especially in order to cope with impacts of the future climate change.
Ferrate As an Advance Oxidator Materials (AOM) for Removing the Congo Red Dyes: Study of Optimization and Kinetics Degradation
Authors: Fatimah Siti , Widyawati Septi , Jannah Nurul , Mei Ayu
Published: April 2021

Ferrate (VI) as an alternative oxidizing material that has a multifunction. This species is able to degrade Congo Red (CR) dyes. The perfomance of ferrates in degrading CR are by free up of hydroxyl ions from the active group then initiating active groups on the CR species. This initiation will cause the CR oxidation reaction to become a simpler compound that is easily biodegradable. The stages of this study were ferrate synthesis, characterization, optimization of the volume of Fe(NO3)3, optimization of pH, and optimization of ferrate(VI) molar ratio with CR. Ferrate synthesis is carried out by reacting a solution of Fe(NO3)3 and oxidizing NaOCl in alkaline conditions. This synthesis produces crystals which formed to sodium ferrate (Na2FeO4) then tested using XRD. The XRD test showed that a good results at a value of 2θ = 32°. Dyestuff oxidation reactions carried out by batch systems and non-oxidized dyes were analyzed using spectrophotometric methods. The results showed that sodium ferrate can effectively oxidize CR dyes with the percentage of degradation of 98.2% at the optimum pH conditions of 9.2, the ratio of the concentration of CR to ferrate was 1:5 and the oxidation time was 20 minutes. The CR oxidation reaction using ferrate (VI) in this study is a first-order reaction with an R2 value of 0.979 and a reaction rate constant of 8.95 x 10-2 mol/sec.
The Relationship Between Frequency of Accident and Roads Geometric Design Consistency in NTB Province
Authors: Elfandari Amadea , Siregar Martha Leni
Published: April 2021

Investigate and measure the relationship between accident frequencies and the consistency of road geometric designs. Methodology: Several accident prediction models from straight section, curve section, and road segment data from variables that combine design consistency. Poisson and negative binomial regression approaches are used for model development. The model obtained can later be used as a quantitative tool for evaluating the impact of design consistency on road safety. From the model obtained, from all the results of the model, it was decided to use the model of negative binomial regression because the model has proven to be undispersed, so that the model results obtained are better than poisson regression. Obtained the final model with exponential and power forms. In addition, the model of the combined data results represents more existing field data, this is caused by several factors that can affect these results. Then, it was found that the model obtained could consider design consistency so that the model could identify inconsistencies better and accurately reflect the resulting impact on safety. Many road conditions in Indonesia are still incompatible with existing geometric road design standards. Consistency in the geometric design of the road must be considered, given that all elements in the geometric design of the road have an influence on the number of accidents that occur on the road. So more consideration is needed for new roads that are designed according to existing standards so as to produce a good road, hoping to reduce the number of accidents that occur significantly.
Overview of Municipal Solid Waste Generation and Energy Utilization Potential in Major Cities of Indonesia
Authors: Qonitan Fatimah Dinan , Wayan Koko Suryawan I , Rahman Ari
Published: April 2021

Problems in municipal solid waste sector remains a challenge to solve for the government of Indonesia. Processing waste into fuel, or known as refuse derived fuel (RDF), are some of the technological alternatives considered to tackle the waste problem. This paper aims to describe recent information on municipal solid waste generation in major cities of Indonesia, including DKI Jakarta, Tangerang, Bekasi, Bandung, Semarang, Surakarta, Surabaya, Makassar, Denpasar, and Palembang, and to overview its potential for energy utilization as refuse derived fuel (RDF). Municipal solid waste generation in Indonesia was assessed based on sources, generation rate, and composition data by year of 2018. Data was obtained from the State Ministry of Environment and Forestry’s (SMEF) national inventory of waste generation website, the National Waste Information System (SIPSN). To assess refuse derived fuel (RDF) potential, waste characteristics such as calorific value, water content, volatile content, ash content is evaluated for each composition. In those cities, municipal solid waste generation rate was 0,69 kg/capita-day, with 1780 tonnes/day generated on an average per city. Household sector was significantly the largest source of municipal solid waste generation in all cities in Indonesia, which contributed 44-75% to total waste generated. The composition of municipal waste consists of 43.78% of food waste, 16.05% of paper, and 14.08% of plastics. The result of calculations showed that, mixed municipal solid waste from those cities has high water content with average of 49.94%, high volatile content with average of 53.34%, and low ash content with average of 6.12%. Calculated heating value of the mixed municipal solid waste is 9.5 MJ/kg which is lower than standard for refuse derived fuel of 12.56 MJ/kg. Therefore, sorting and pre-treatment mixed municipal solid waste in Indonesia is necessary to meet the criteria of refuse derived fuel material.