Proceedings of the 4th International Conference on Experimental and Computational Mechanics in Engineering

Total knee arthroplasty (TKA) is one of the most successful ways of treating pain and functional limitations due to osteoarthritis. Asians and Middle Easterners need a large range of flexi angles for religious, social, and cultural activities. Prayer activities and seiza required flexible angle from 150° to 165°. To support these activities, a TKA high flexion (high-flex) type is required. The application of high-flex TKA causes a difference between extension gap and flexion gap, called gap difference. Gap difference is strongly influenced by posterior tibial slope (PTS) and single radius system, and it causes TKA instability. This study aims to analyze the stability of AKJ with GD measurement on a single radius system with a computer-aided design (CAD) approach to prayer, social, and cultural activities for Asians, especially in Indonesia. This study uses the CAD approach with stages that are implant scanning, surface processing, curve processing, components improvement, and gap difference measurement. This study has successfully tested the stability of the model against the difference between gap extension and gap flexion. TKA model with a maximum of PTS 6° can be recommended for the purposes of Asian activities, especially Indonesians in religious, social, and cultural activities. In the future, stability tests will be needed for the movement of anterior–posterior translation.

This study aims to analyze the causes of crankshaft failure. The methods implemented to examine the value of stress acting on the crankshaft include visual observation, SEM observation, chemical composition testing, and hardness testing. Furthermore, the visual observation of the fourth crankpin fracture surface showed the presence of beachmarks and rivermarks that become characterize fatigue fractures. The SEM observations showed that the crack originated around the fillet on the fourth crankpin. Furthermore, the chemical composition test showed that the type of material used on the shaft was Steel Alloy ASTM A29 standard Grade AISI 4140. The hardness test showed that its value is not homogeneous at each test point with an average value of 99.67 HRB. This exceeds the standard hardness of the AISI 4140 material, which is 92 HRB, leading to the decrease in the toughness of the crankshaft material. The lower surface hardening in the crack initiation region triggers initial defects in the material, while there was friction with the bearing. Because the crankshaft experiences dynamic loads, over time crack propagation occurs from the initial crack to the final fracture.

The fibula is a small bone that runs parallel to the tibia in the lower leg. The fibula receives 15% of the human body weight. Under certain conditions, fractures can occur in the fibula due to certain human activities. One of the medical solutions to treat fractures that occur in the fibula is to install internal fixation. In the case of internal fixation, the interaction between bone and bone, bone with plate, bone with bolt, bolt with bone, is complicated to study experimentally. Numerical analysis is an option to study these interactions. Several parameters that affect the analysis results need to be fully known to perform an excellent numerical analysis. The purpose of this study is to investigate the impact of mesh size and coefficient of contact model on stress distribution on the internal fixation of fibula fracture. They were analyzed by finite element method under loading conditions that represent the standing position. The stress distribution was analyzed using ANSYS software. Three mesh sizes are selected, namely coarse, medium, and fine. Friction contact models were applied to the area between the fibula and the implant. The load used in this study represents three human body weights, namely 80, 90, and 100 kg. The material chosen for the plate and screw is AISI 316. Among the three meshes used, it is seen that the fine mesh produces the highest stress and is concentrated in one particular area. Furthermore, the coefficient friction of the contact model did not produce any significant difference in the stress distribution on internal fixation.

The effect of tempering temperature on mechanical properties of the quenched low alloy steel was studied. The as-received low alloy steel samples were heated to 950 °C, held for 30 min, and then oil-quenched. The as-quenched samples were finally tempered in the temperature range of 200–600 °C for 30 min. The chemical composition of as-received alloy steel was determined using spectrometer. The microstructures of the samples were observed using optical microscope. A Rockwell hardness test was done to measure the hardness of the alloy steel samples, and a Charpy impact test were conducted to measure the impact toughness of the samples. The results showed the microstructures of the as-quenched and as-tempered samples consist of martensite with different orientation and small inclusions of irregular shapes. Compared with the as-received low alloy steel, the hardness of the quenched steel increased while the impact energy decreased. In comparison with the quenched samples, increasing tempering temperature in the range of 200–600 °C would improve the impact energy of the tempered steels, and it significantly increased above 400 °C.

Quality is a primary focus to both maintain and increase customers. A manufacturing production process and service business’s failure impacts operational costs. Assessments are needed to instigate fabrication process failure and maintain good quality output. PT AA is a fabrication contractor firm that experienced process failures in the steel fabrication division. This study aims to evaluate the steel fabrication process to recommend improvement solutions to eliminate failures at the fabrication stage. Failure mode and effect analysis was used as the research approach. The result of the research found that two defects, namely peeling and ruuns, in the painting process gain the highest defect numbers with 117 compared to other stages. With a score of 576, the highest risk of defects ruuns the painting process. Recommendations for improvement are that the company’s management regularly provides briefings and education on the importance of SOPs and installing SOP stickers on every painting equipment and tools.

The Archimedes screw turbine (AST) is a type of turbine that produces micro-hydro power that can operate at low heads. In this article, the performance of AST is experimentally investigated for the angle of an inclination. This study aims to analyze the effect of variations in the turbine screw shaft angle on the shaft rotation, output power, current, and voltage generated. The AST turbine’s lower inclination angle (25°) results in higher efficiency. The test results show that the optimum inclination angle is obtained at 35° for water discharge 0.011 m3/s delivering a torque of 2 N.m.

Strengthening and repairs need to be carried out on the clinker silo of the Lhoknga Cement Plant, where there has been significant damage, making the silo unable to function at full capacity. Damage to reinforced concrete where cracks and spalling occurred as well as corrosion of reinforcing steel was assessed. The assessment was carried out using the following methods: visual inspection, rebound hammer test, ultrasonic pulse velocity test, and corrosion potential measurement using a half potential cell. From the assessment results, there have been many cracks and severe corrosion in the reinforced concrete slab, which reduces the strength of the structure. For this reason, the structural strengthening of the slab using CFRP was carried out so that the structural capacity can increase and be able to withstand the required working load. Meanwhile, in the clinker silo wall, the potential corrosion is still at a moderate level and does not pose a significant hazard to the structure in the near term.

The main idea of this article is to provide further knowledge related to the application of pure biodiesel in a custom power generator. Previous research has shown preliminary results regarding the potential of Pangium edule. Biodiesel as feedstock and has been tested to run a diesel engine with lower rotational speed. The biodiesel in this research has been prepared using a heterogeneous catalyst derived from a palm kernel shell impregnated with K2CO3. In this research, small alternator is driven by Yanmar TF65 R-DI multifunction diesel engine, which is easily assembled and has been utilized as a power generator to be evaluated. The engine was tested under various biodiesel blend with given load and connected to multiple instrument to record data required, i.e. engine speed (rpm), fuel flow (ml/sec), voltage (V), and current (A) readings. The data series then used to analyse the engine performances. The custom power generator has been designed to work at 5.5 kWh in prolonged operation time, suitable to supply typical household wattage in the region, ranging from 0.9 up to 3 kWh. The fuel mixtures containing 20% biodiesel, or B20, is still desirable to use in general multipurposes diesel engine. While B30 show similar potential but it does not show a similar performance as in higher rotational speed diesel power generator as demonstrated earlier. However, PE biodiesel still shows a promising performance as an alternative source of diesel engine fuel.

The purpose of this study was to determine the effect of hyperparameters on the performance of BEIA in detecting corrosion in reinforced concrete. BEIA was run with fifteen data of potential measurement values on concrete surfaces. Variations in geometry size, cognitive values (a1), and social parameters (a2) were performed in this study. Simulation result show the hyperparameters can affect the performance of BEIA in finding the location of corrosion in reinforced concrete. Due to the effect of hyperparameter values on BEIA performance in detecting corrosion on rebar, the recommended cognitive parameter value is < 0.4; meanwhile the recommended social parameter value is 0.6 < a2 ≤ 0.9.

Coconut oil waste is considered to be a promising prospect for use and development as natural composite materials. Before use, coconut oil fibers are treated for 24 h in an alkaline treatment of 2% NaOH. In this study, coconut coir fiber was used as a reinforcement for polymer composite materials. The purpose of this study was to make a table tennis racket from a composite polymer material reinforced with coconut fiber. Making of the table tennis racket is by using a press machine. Mixing of coconut fiber and polyester resin is based on mass fraction with a weight ratio of 10:90. Making table tennis racket is by hand layup and compressing mold. Coconut coir fiber is arranged randomly with a layer on a mold in a press machine. The results obtained are a table tennis bat with a composite material that has a thickness of 6 mm and a mass table tennis bat after rubber coating on the bat part is 203 gr.

Porous structures have shown promise in biomedical applications, particularly for artificial implants, because they provide a large surface area for bone ingrowth. A simulation analysis model was developed in this study to evaluate the mechanical properties of various designs based on cubic unit cell scaffolds with varying strut geometries at the same porosity. Based on the diameter and cross-section type of the struts, porous bone scaffolds with the same porosity were developed. The porous structure bone scaffold with square cross-section struts is larger based on the pore size measurements. The porous structure bone scaffold with square cross-section struts has the highest compressive strength and modulus elasticity, according to this study. All bone scaffolds with porous structures, however, may meet the trabecular bone criteria (pore size, porosity, interconnectivity, and biocompatibility), but not the cortical bone criteria. Biomaterials with higher mechanical properties, or polymers combined with ceramics, will need to be researched in the future to match cortical bone's mechanical strength.

Electrical energy is one form of energy that cannot be separated in life in the modern era. Over time, energy needs continue to increase, while fossil energy reserves are decreasing and even running out. This study uses several stages, namely meeting the needs of alternative energy, one of which is by modifying a car radiator or dynamo amperage on a car that functions as a generator of electrical energy when the electrical energy is still alive to supply electrical energy to the car, especially to charge electric batteries (car batteries). This study aims to determine the output in the form of speed, voltage, current, and power generated, in order to determine efficiency and good use for homes that are far from PLN supply and to save PLN costs. The results obtained at rotational speed and load will affect the low speed output because the higher the rotational speed, the higher the voltage and frequency. The larger the load, the lower the voltage and frequency. Under no-load conditions, the tested alternator can produce an average voltage of 664 V, the average current is 30.2 A, and the average speed is 4632 rpm. While the tested alternator is able to produce an average voltage of 484 V, the average current is 100 A and the average speed is 3489 rpm.

Foaming agents for fire suppression on peatland were formulated from the saponification product of palm oil fatty acids, namely sodium laurate and potassium palmitate. This study aimed to obtain the best formulation of sodium laurate and potassium palmitate as raw material for foaming agent concentrate through formula selection based on physical parameters foaming ability, foam stability, and surface tension. In addition to obtaining the best formula, foam liquid performance test for the foaming agent was also conducted on the peat fire suppression applications. Formulation of sodium laurate and potassium palmitate that produce the best foaming agent concentrate was 20% sodium laurate, 5.58% potassium palmitate, and 74.42% water, which produced a foaming response of 393.58%, foam stability of 69.59%, and surface tension of 31.11 dyne/cm. Foam performance test for the mixture of water and foaming agent showed that peat fire could be extinguished in 3 h 50 min 42 s using 4.56 L/m2 extinguishing solution. Meanwhile, fire suppression with water requires 5 h 31 min 59 s, with the application of 9.72 L/m2 solution. Water mixed with a foaming agent concentrate can extinguish peat fires faster than using water alone, besides being faster the application of foaming agents can reduce water consumption.

Musculoskeletal disorders frequently occur in various types of work, including laparoscopic surgeons. The surgeon profession is classified as a high-risk occupation and may have musculoskeletal disorders. Surgeons who suffer from these disorders experience illnesses ranging from mild to severe because the muscles often receive long-term static loads. These causes can be prevented when working in a seated position. In this work, the investigation being conducted is to design a chair as a surgeon's aid that consists of a base platform, seat height adjustment mechanism, seat cushion, backrest, and handrest. In this paper, a rectangular platform is analyzed using a finite element model. The analysis results by considering the structure as a truss produce the largest stress of 34 MPa compared the structure as a frame of 30 MPa. These two approaches lead to the conclusion that the structure computed as a truss is more secure than the analysis of the structure as a frame.

The use of composite materials with natural fiber reinforcement has experienced rapid development in the automotive industry to apply synthetic materials that are expensive and not environmentally friendly. Biocomposite is a type of composite consisting of a polymer matrix and natural fiber reinforcement. Natural fiber materials are used instead of conventional non-renewable materials. In this study, the vacuum-assisted resin infusion (VARI) process was used for composite fabrication using woven kenaf and ramie fibers. The Taguchi experimental design method with the L932 orthogonal array matrix in this study was used to obtain optimum composite fabrication parameters with natural fiber reinforcement. Material test such as impact test and flexural test is used to obtain experimental responses. The results of the study using the RSM method obtained the optimal combination of manufacturing parameters, namely by choosing a low concentration of NaOH (4%) and a high post-curing temperature (120 °C). With these optimal parameters, the optimal flexural and impact strengths that can be achieved are 0.261 J/mm2 and 79.658 MPa.

Musculoskeletal disorders (MSDs) are complaints of pain in body parts due to poor posture, repetitive movements, and movements with too large an angle. This study examines operators who work in the administration department in a learning industry in Yogyakarta. This study aims to determine the level of risk that exists in static workers using the LS-CMDQ questionnaire and the ROSA method. The results of the LS-CMDQ questionnaire show that the back has the highest score of 14, and workers experience pain in that area 3–4 times a week. The ROSA method shows a value of 5 for administrative activities, which is very dangerous in the long run. The recommendations are redesigning an ergonomic work chair, adjusting the work position with minimal movement, and tilting the wrist not more than 15°.

In the development of the times and technology, demands for forms and characteristics have a good aerodynamic value. As a result, various types of new models are emerging rapidly in the automotive market. In addition, many drivers modify their cars. One of them is by adding a body kit or just adding a spoiler to make it more esthetic. As time goes by, many car manufacturers pay attention to several aspects in designing their cars. One of them is aerodynamic. The aerodynamics performance of a car is affected by the drag coefficient (Cd) or drag when the car is in motion. Furthermore, to get this Cd value, a study will be carried out that focuses on the effect of adding spoilers with NACA 2412 on vehicles. The research can be carried out using the CFD simulation. In the study, a simulation was carried out using a Hatchback car and two spoiler models with a NACA 2412 airfoil profile. The result obtained is that a car without a spoiler produces a Cd of 0.562, and for a car model with a spoiler 1, it produces a Cd of 0.383, while for a car with a spoiler of 2 it produces a Cd of 0.409.

This study aims to determine the effect of road surface contours on the life of car suspension components. In this study, strain gauges were fixed on the critical points of a coil spring and a lower arm. The car went through smooth and rough road surfaces with speeds over 30 and below 20 km/h, respectively, for 60 s. The strain signals obtained were analyzed according to the Coffin-Manson, Morrow and Smith–Watson–Topper models. According to the strain amplitudes measured, the coil spring fatigue life of the rough road surface was 16% lower compared with the smooth surface, whereas the lower arm of the rough road surface was 27% lower than the smooth surface. It was also found that the coil spring failed 36% faster than the lower arm when driving on the rough road surface. This is because the contour of the surfaces provides a vertical load affecting the coil spring at higher rates than the lower arm. It is in accordance with the function of the coil spring which works to reduce the load vertically.

One product that needs attention, especially regarding packaging, is the talang salted fish product, which has been trading talang salted fish without sacrificing packaging. This study aims to organize the packaging of talang salted fish so that it has a selling value that can attract consumers to shop. The strategy used is value engineering and the analytical hierarchy method (AHP). First, the engineering method is feasible to be applied to expand the value, performance, and value of packaging design, which consists of brand name criteria, Internet weight measurement, product identity, attractiveness, color suitability, typography, and font size. Then, the analytical hierarchy method is applied at the analysis stage to verify the priority criteria that follow consumer desires. The results showed that the chosen design with the best performance was an alternative (A-B-D-E), to be precise, the display was made of clear plastic packaging material, the colors used were bright, the packaging was rectangular, and each capital letter was used. This elite alternative design includes a value of 0.039. This value is obtained from the performance of 38.9 and the price of IDR thousand per pack. The novelty of this research is that the packaging model is easier to recognize by customers because the packaging is more attractive, more hygienic and does not cause odor from talang foreign fish. The method is more innovative because of the combination of product design and the selection of product alternatives if the product design uses value engineering and if the alternative design uses AHP.

The amount of solid waste from the distillation of citronella oil is mostly still not utilized optimally so that it only accumulates and pollutes the environment. Especially in Aceh Province, waste from citronella oil distillation on average is only burned when it has accumulated. The potential for the amount of waste is relatively large, with the area of citronella in Aceh Province being 17,445 ha, the waste generated from the distillation process can reach an average of 6,959 tons/year. When managed properly, the waste still has a high economic value, one of which is by turning the waste into briquettes. This study aims to analyze the feasibility of processing citronella solid waste into briquettes with a focus on the financial aspect. Processing refining citronella oil solid waste into briquettes is through five stages starting from the drying process, raw material chopping, pyrolysis process, refining, to briquetting. Testing was conducted by looking at the value of the break even point and net present value. It costs IDR 19,652,000 as investment cost to make briquettes from citronella oil refining solid waste. Based on the BEP value, briquette products must at least be able to be sold at a price of IDR13,525/kg to cover the cost of production, while the production unit should be able to produce 8.95 kg briquettes every day. Based on the calculation of the net present value which is worth IDR 5,380,817, it indicates that the business or investment design is economically feasible to be implemented. However, the by-products of liquid smoke and gas from pyrolysis have great potential to be utilized.

There was a failure in the truck’s rear driveshaft in the spline during the transportation of rock and sand in Aceh Besar, in Indonesia. Therefore, this research aims to analyze the causes of failures in the rear driveshaft of the truck by performing a finite element analysis (FEA) simulation. It was discovered that the standard for the shaft material is AISI 4150. Based on the results, the maximum shear stress was s 233.21 MPa, this has exceeded the allowable value of 80.7 MPa and shear stress Tresca which is 190 MPa. Furthermore, the Von misses shear stress analysis obtained is 426.2 MPa, which is above 179.13 MPa. The analysis of the stress intensity factor also obtained an average value of 27.7 MPa√m, which is more than the 10 MPa√m (KI > KIC) fracture toughness value, thereby triggering crack propagation to fracture.

This work aimed to promote improvement of manufacturing through adopting smart manufacturing in Thailand. As the manufacturing industry in Thailand moves toward Industry 4.0, many SMEs are struggling to start up and invest. To help them, the Thai and Japanese governments are collaborating to provide a Smart Monodzukuri support team to assist SMEs to have more skills and be more competitive. This team will learn techniques to implement Japan's Industrial Value Chain Initiative (IVI), an organization that uses cyber-physical manufacturing, and encourages all companies to take part in a “small start” initiative. This work provides a case study using an auto parts manufacturing company. We describe how a Smart Monodzukuri team could collaborate with this company's staff following the IVI guidelines. The results show that by using the IVI idea, the team could incorporate cyber-physical manufacturing with few difficulties and low investment. This is the first simple and feasible step toward Industry 4.0 for SMEs.

Most infectious diseases are caused by viruses that are spread from one person to another through the air. Isolation room is a room that keeps virus in infected people from spreading to other people by maintaining temperature and humidity. Therefore, a system is needed that regulates the isolation room to remain sterile, where this system must control and maintain the stability of air circulation in the room. For this purpose, this study proposes the design of an automated control system to regulate the temperature and humidity in an isolated room by controlling the supply air with damper. The method that is used in making this control system is experimental and analysis from sensor readings that will be used as a sign of decision-making for the damper output that will control the air flow to the isolation room with closed loop algorithm for the system control, the controller will send digital signal to the damper relay based on sensor reading, so that the data results of the experiment and analysis can see whether the control system can work well or not. The successful performance of the control system is seen from results of sensor readings; when the system changed the damper position it can maintain the isolation room situation around 22 °C to 24 °C for temperature and 50% until 60% for the humidity.

Assembling particleboard made of palm oil empty fruit bunches requires good quality holes so that the assembled product can meet quality requirements. Machinability is critical in producing high-quality holes, especially for manufacturing products from particleboard. It is owing to low level of density and structural strength of particleboards. Accordingly, the machinability of the particleboards in terms of hole quality is a primary concern in this study. The hole quality was assessed in terms of the diameter deviations, the hole’s perpendicularity and the surface roughness. The results showed that the response deviations were relatively large for all observation aspects. In addition, the variations in cutting conditions and the appropriate selection of the tool geometry failed to render their defined effects on the hole quality. In other words, the effect of cutting conditions and tool geometry on the hole quality is difficult to define accurately.

Cooling tower is a heat transfer device that works through water media, along with air used to cool the temperature using water media with direct contact with air which causes some of the water to evaporate. To improve the performance of the cooling tower, many trials and research have been carried out, one of which is by adjusting the hole in the cooling tower area as a liquid medium distribution. From this phenomenon, this study examines the effect that occurs on the number of holes on the rate of movement of the flat plate cooling tower with the overall height of the cooling tower 2.4 m, the number of distribution media for the cooling tower water flow is 5 plates in succession, and the length of each plate is 0.7 m with a width of 0.5 m. Plate variations are given to the cooling tower, namely plate without holes, plate 25 plate holes, 35 holes, 45 holes zig-zag hole model on the cooling tower. The diameter of each plate hole is 0.02 m with the slope ratio of each plate arrangement which is 15°. The results showed the highest heat transfer rate occurred in the cooling tower water inlet temperature of 75 °C. The plate variation used was the plate without the inlet hole model. And the lowest heat transfer rate occurs at the inlet water temperature of 55 °C with a plate variation of 45 holes with a zig-zag hole model. So that the variation of the hole pattern affects the temperature change with the heat transfer rate on the tower performance.

Compressed Natural Gas (CNG) is an alternative fuel used to solve cleaner exhaust emissions, global warming, and limited world fossil oil production problems. It emits cleaner gases during combustion, is economical, can be applied to light/heavy vehicles, and has good adaptability to diesel/petrol engines. This research reviews the application of CNG in vehicle engine articles published from 2017 to 2021. There were 82 articles on CNG, while 38 were on CNG as vehicle fuel. The articles reviewed were classified in several focus areas of research, such as the development of the ignition system on the CNG engine, the injection method, the application of Exhaust Gas Recirculating (EGR) technology, variations in the compression ratio of the CNG engine combustion chamber, the application of Reactivity Controlled Compression Ignition Engine (RCCI) on CNG machine, system modeling, mixer and method. The results showed a lack of research on the development of CNG that integrates intelligent control systems. Therefore, further research is suggested to explore the potential effect of the next period.

Analysis of strain distribution is a key topic in mechanical engineering. The two traditional techniques for measuring strain are making grids on test samples and using a strain gauge. Both of these methods require a lot of time and work. Digital image correlation (DIC), which is based on cutting-edge camera and computer technologies, is now an essential tool for measuring strain fields for a variety of test specimen scales. The fundamental idea behind DIC is to capture the entire process as images and then process those images so that they can be compared with deformed image sequences. This comparison can be used to determine the displacement and strain distribution down to the sub-pixel level. Several studies have highlighted the DIC method in solving bio-mechanic cases. However, limited knowledge is available regarding the deformation and strain distribution of bone plate implants. The goal of this study is to use the digital image correlation method to measure calcaneal bone plate deformation and strain during compression loading. A three-point bending test was performed on a calcaneal plate of 3.5 mm and screws that were fixed on the Sander’s IIB fractured platform. The method of DIC measurement was discovered to determine the location and magnitude of strains at the bone-screw interface as well as the magnitude and location of plate stress.

In our modern environment, electrical energy has become the most important resource. However, it has access to many areas of the world, particularly agriculture. As a result, there is a huge need not only to identify alternative energy sources, but also to make them available to each sector of the world. Solar energy could entirely meet the energy needs, yet it is currently the most untapped energy resource. To achieve an alternate method of agriculture product drying system, a dual-energy dryer design employing maximum power points tracker was designed in this research. Solar panels will generate electricity to charge the battery throughout the day, which will subsequently be utilized to power the system, increasing system efficiency. The results of real-time data using Internet of Things show the results of battery performance and battery output loads as well as significant load devices by applying maximum power point tracker as the main mainframe in increasing the performance of the double dryer system. Better output results from this dual drying system at maximum power control. The novelty of the research in this activity shows that the maximum power capture value is more efficient in the dual-energy dryer system and the system performance is higher and more accurate with data obtained through the Internet of Things.

In a particular application, thermoelectric refrigeration has an unrivaled excellence which other refrigeration systems may fail to accomplish it. Especially in application related in medical purposes. An accurate temperature stability is essential for this application. This study examined the performance of a thermoelectric cooler box with a cold sink that fills with Phase Change Material (PCM). Two different PCM were tested and analyzed for their energy efficiencies related to the thermoelectric cooler box. The cooler box has 240 × 260 × 265 mm dimension and is supplied with two Peltier modules. The power supply to the module was controlled by a thermo-controller and set to interrupt the supply if a temperature condition was achieved during the test. The purpose is to exchange the cooling supplied from thermoelectric with cold PCM inside the container. Thus it can reduce the power consumption of thermoelectric. The result shows that PCM 2 which mixed of 95% of tap water and 5% soya ester could hold the temperature of the cooler box more stable and longer than tap water as PCM 1. Furthermore, the result also shows that using PCM 2 has potential energy storage in thermoelectric application devices compared with PCM 1.

Thermal energy storage using phase change material (PCM) is considered a promising technology for future energy needs due to its low-cost and high storage capacity under isothermal conditions. Supercooling of phase change materials (PCM) during the transition process from liquid to solid is a major problem in thermal energy storage, which reduces energy efficiency and exacerbates energy wastage. This study focuses on the supercooling characteristics of PCM under heterogeneous nucleation, which provides a new idea to investigate the effect of nucleating agents on the supercooling rate of aqueous solutions. Understanding, predicting, and, where possible, preventing, or at least reducing, supercooling is particularly important for latent heat thermal energy storage systems, as the temperature differences within them must be small to achieve higher efficiencies. Water is the most popular PCM today because it has good characteristics despite high supercooling. Various PCM samples were prepared and tested in this study to reduce water supercooling. The sample comprises water and propylene glycol solution in various percentages (10/90, 20/80, and 30/70). The t-history method is applied to test the samples. The results showed that the water supercooling decreased with the increase in the percentage of propylene glycol solution in water, from 10 degrees to 6, 4, and 2 degrees, respectively, making it suitable for cooling applications.

Nowadays, in many industries such as marine, aerospace and civil, the utilization of several materials must undergone a product testing and one of it is a compression test. The purpose of the compression test is to clarify whether the material possesses excellent mechanical properties or vice versa peculiarly with regard to the compressive behaviour. The compression test will determine the compressive strength, elastic modulus as well as the specific compression of the material. In this research, the simulation of the compression test of the activated carbon composite will be executed via Finite Element Analysis. The activated carbon that will be used in this research is softwood materials such as Mangrove Bark Activated Carbon (MBAC), an eco-friendly type activated carbon since it is derived from the mangrove bark of the mangrove tree. The model of the activated carbon composite with different diameter will be tested on the simulation software to compare the compressive strength of each models.

At this time, autonomous mobile robots are used to move groceries. Therefore, object classification is required to move groceries to avoid collisions with other objects. Object classification using a convolutional neural network (CNN) can significantly increase mobile robot autonomy. Therefore, this paper investigates object classification performance using CNN for several environmental conditions. The research method is computer simulation using several steps: image collection, image annotation, and training. SSD Mobilenetv2FPNLite was used as a CNN model for object classification. The objects for the classification using the pre-trained CNN are cars, motorcycles, persons, and goods rickshaws. The results enabled us to estimate the effectiveness of using pre-trained CNN for classifying different objects. The result also shows that objects can be recognized with a classification accuracy of 100%.

A motorcycle is commonly used by people in Indonesia as a transportation device. It is because this device is flexible and affordable as well as easy to maneuver. However, the risk of driving a motorcycle is an emergence of the Carpal Tunnel Syndrome (CTS) on the wrist aside from the accident. This syndrome occurs when tissues surrounding the flexor tendons swell, providing pressure on the median nerve. It is caused by the vibration on the motorcycle handlebar that results from the engine and it will impair the muscle work. The objective of this study is to investigate the correlation between the Flexor Carpi Ulnaris muscle contraction and vibration occurred in the motorcycle handlebar and how much the muscle contraction comes about. An experimental study was conducted in an ergonomic laboratory in which six respondents have participated. Electromyography was used to identify Maximum Voluntary Contraction (MVC) on Flexor Carpi Ulnaris muscle which is functioned as controlling the throttle, clutch, and brake levers. Manual and automatic motorcycle with 110 and 125 machine capacity, and 1000 and 5000 speed level for a case study. Statistical analysis was conducted to test the hypothesis. The result of this study shows that the percentage of maximum voluntary contraction on flexor carpi ulnaris is higher on a manual motorcycle than the automatic motorcycle in 5000 rpm for 110 and 125 machine capacity, respectively, in which it will be higher as long as vibration increases on a motorcycle handlebar. An important finding of this study was that the machine capacity, the type of transmission, and the speed of engine will generate the vibration on hand’s muscle contraction. Thus, it is required to design the personal protective equipment to mitigate the affliction on hand for next study.

This research scopes to the modelling and simulating of one section of wing-type structure subjected to a bird strike. Modelling and simulations are performed through finite element (FE) approach by using ANSYS Workbench (Explicit Dynamic). The bird is modelled as a rigid body, having a similar weight to an actual bird. Varying desired parameters of the leading edge—curvature radius (R), skin thickness (T), and number of ribs (N) behind the leading edge—provides a better understanding of the extent of each design modification. Six different values of R and T are studied, with none (N0), one (N1), and two ribs (N2) behind the leading edge’s skin considered. By impacting the model with 120 m/s of initial velocity, the effect of T is seen to exhibit linear relationship with energy absorbed (EA) and specific energy absorbed (SEA). For R, a peak EA and SEA has been identified. Adding ribs behind the leading edge’s skin was also proven to provide more strength. Spacing of ribs is expected to vary the performance. The effect of impact location has been analysed as well.

Droplets are liquids or splashes of water that are expelled through the respiratory tract when a person talks, coughs, or sneezes. The average size of the droplets released during sneezing is > 5 µm with a distance of < 1 m. Meanwhile, when speaking, it is 5 µm at a distance of 1 m, which is often called nuclei or respiratory droplets. Due to their smaller sizes and the inability to observe with the naked eye, the direct spread of infections through these droplets is a major factor in the increase in disease cases. Therefore, this research is focused on the set-up of droplet observation instrumentation in the room, where the velocity of airflow is neglected. The novelty lies in determining the size distribution of droplets produced and examining the transmission speed when someone sneezes. The results showed that the set-up successfully identifies the droplets expelled during sneezing. The mucosal sac expands and is dispersed and retracted, which makes the ligaments to be visible when pulled or detached from the mother's pouch, causing the sac to disintegrate and form droplets. Based on observations, the number of droplets produced when sneezing is approximately 109 particles, where 39% are 5 µm and 61% are above 5 µm, with a speed of 2.08 m/s.

In automobile and consumer product industries, companies require long-life reliable, lightweight, and high performance self-lubricating composite materials, properties of these materials are promising materials for guide-ways, bearings, bushes, and piston rings that demand low friction and wear in the absence of wet lubrication. The present work investigates the tribological properties of hybrid composites. PEEK, PTFE reinforced with some new additives. Tribological tests are conducted at different temperatures on tribometer under dry sliding conditions and different environmental temperatures (room temperature) to elevated temperature. The experimental tests were conducted as per standard duration according to work conditions for all specimens. The hybrid composite exhibited lower friction and lower wear rate than those of without hybrid composite materials at both low and elevated temperatures. The combined effect of solid-state lubrication of hybrid PTFE composite was found satisfactory at higher temperature. Dominating friction and wear mechanisms in the hybrid polymer composites at the different temperatures were exhibited to get PTFE adhesion. Formation of transfer films on the steel surface was also analyzed at various temperatures.

Mature gas field optimization for new local company for operatorship shall begin with main production problems identification and cost readiness, for Gas Compression Area Cluster IV (APO) and Unit 26 (Point B) operation, the main problem is the production facility equipment needs to modify surface production facility to adapt the current operating conditions. Excessive fuel own use has more challenging for new operator, in additional, several joint agreements in Facilities Sharing Agreement also need to be considered. First and foremost, generating surface production facility resizing programs that directly contribute to reduce fuel own use should be put on priority with business scheme toward Operation Expenses i.e., rental equipment models should be put in first consideration as the company needs cash to do exploration in the area. Gas Compression is a vital system in the distribution of Gas. The existing gas booster compressor cluster IV (K/KGT-4920) and gas booster compressor unit 26 (K/KGT-2601) are 2 (two) stage LP/HP Centrifugal machine driven by Gas Turbine. Fuel gas consumption of K/KGT-4920 in the amount of 3.8 MMSCFD and fuel gas consumption of K/KGT-2601 in the total amount of 6.2 MMSCFD. There is one project were in Cluster IV Gas Compression area that will be executed to reduce fuel own use in gas booster compressor package for Cluster IV and Unit 26 as well as increasing sales gas. Resizing of new gas booster compressor package cluster IV (K/KGT-4920) is adjusted to the gas booster compressor package unit 26 (K/KGT-2601) output by means directly delivered to the Inlet treating unit of Point B. The new size of gas booster compressor will reduce total amount of fuel gas consumption ± 6.9 MMSCFD, therefore, the equal gas sales will increase in the same amount that will contribute extra income of 37,464 USD on daily basis. Based on the project economic valuation from Q4 2023 up to Q4 2028, the expected Net Present Value (NPV) worth 27,800,000 USD after replacement of the existing compressor looks profitable.

The study of solid fuel combustion characteristics is still continuing due to increases in demand of clean and renewable source of energy. Agricultural waste such as coffee pulp is an alternative source of biomass which has not optimally been utilized. The aim of this study is to examine the characteristics of the solid fuel combustion of densified coffee pulp biochar in a purposely built furnace. Initially, a simple mechanical design of combustion test furnace was prepared equipped with data logger for measuring weight lost and temperature changes. As main testing fuel, arabica coffee pulp was pyrolyzed and densified by adding starch binder. For comparison, locally available commercial coconut briquette and young brown coal were also tested under similar condition. The weight of each fuel sample was ≤ 50 g. Based on combustion test results, required time for ignition of coffee pulp and coconut briquettes was 2 min, and it took 5 min for coal. The combustion rate of densified coffee pulp biochar, coconut briquette, and coal was 0.5 g/min, 0.59 g/min, and 0.23 g/min, respectively. The maximum combustion temperature of 480 °C at 35 min, 375.9 °C at 45 min, and 487 °C coal at 140 min was observed during the combustion test of densified coffee pulp biochar, coconut briquette, and coal, respectively.

The innovation of agricultural equipment influences an increase in crop production. The process of planting vegetables is still a problem for the farmers, so it needs to be solved by designing tools in agriculture. This paper discusses the design and operation system of a small robot for planting spinach water. This study aims to design a small robot that can be used to plant spinach water seedlings quickly and with minimal labor. The planting operations for the spinach water seedlings include making holes, inserting seeds, and closing holes again. The mechanism for planting spinach water seeds is modeled as a robot that has a frame, electrical components, seed shelter, and soil hole punch. The design results of this robot can be the planting process approach of 25 kg of seed load. The operation of robot was tested using a control system on a Bluetooth-enabled cell phone. The robot control system operates on a standard electrical voltage range of 5–12 V and has a system performance of 16 min. With this workload, the robot can plant seeds on a 12 m × 0.5 m plot of soil.

Air conditioning (AC) systems are the main energy-significant services in hotel buildings. There is, therefore, remarkable potential to increase energy efficiency use of the hotel AC systems by optimization of both their system selection and operational characteristics. This paper presents an inclusive evaluation of commercial AC systems that can be appropriately functional for a case study star hotel. The hotel considered consists of resorts and villas of cooling load as high as 2400 tons of refrigeration. Site investigation, AC-specified characteristic review, and numerical approach were applied. The evaluation involved operational characteristics, coefficient of performance, and power and energy use per year. The evaluation results showed, for hotel building application, the central AC systems which generally have better diversity factor, could provide flexibility in installed system capacity. The results also showed that the water-cooled chiller system could perform with higher COP compared to the other AC systems. Additionally, the annual energy efficiency of the water-cooled chiller system was also found very superior with energy savings more than 50%. After central water-cooled chiller system, it was found that a modular water-cooled chiller system could also provide an excellent energy performance. Finally, the evaluation results can provide the most suitable AC system alternatives, specifically in hot climate country applications, to hotel facility consultants, hotel building contractors, and hotel owners.

Isolation rooms for patients with infectious diseases in particular have a very high risk of being contaminated with various diseases such as Covid-19. Covid-19 is a severe respiratory disease caused by the coronavirus family that has become a worldwide pandemic. This type of disease spreads very quickly through the air. Isolation rooms for patients with infectious diseases must be prepared to prevent the spread of disease through the air. The air supply in the isolation room greatly affects the temperature and humidity of the air. This study aims to determine the air supply to the distribution of temperature and humidity in the isolation room. The research scheme was carried out in two conditions: Firstly, the isolation room was in normal condition without any air entering or leaving (diffuser–exhaust Off) and secondly, the condition of the isolation room being supplied with air (diffuser On–exhaust Off). The results of the first scheme show that there are slight differences between each of the measurement points (T1, T2, T3, and T4). The maximum temperature at point T1 is 27.85 °C, at positions X = 0.2 and Y = 1.9, while in other positions, there are no significant differences. This is because the positions X = 0.2 and Y = 1.9 are the locations of the measurement point on the patient’s bed. The results of the second scheme in the diffuser area show that there is a significant change in temperature, recorded at the measurement point T1. The minimum temperature reaches 21.18 °C, while for the measurement points T2, T3 and T4, the minimum temperatures are 19.73 °C, 19.68 °C, and 19.63 °C, respectively. Other areas also experienced changes in temperature, and the highest temperature occurred at the measurement locations X = 0.2 and Y = 1.9, where these locations were at the top of the patient's bed and far from the diffuser position. Thus, the measurement results of each condition can be the initial basis for continuing further research.

Solar radiation is a varied source of energy, and the mismatch between the availability of these sources and domestic energy demand is a major challenge that must be faced. Energy storage system can be considered as effective solution to overcome the challenge in solar energy utilization. In this work, a thermal box was prepared as energy storage testing apparatus by using a 5W lamp as the heat source located at the center of the box. In the middle of thermal box, the sample of phase change material (PCM) was placed and monitored in order to find out the charging and discharging characteristics. The purpose of this study was to investigate the charging and discharging performance of NaCl–KCl eutectic salt at various ratios. The specific heat capacity and density of all PCM samples were also tested during this investigation. The changes in temperature were observed through type-k thermocouple sensors equipped with data logger. In general, it can be concluded that reducing KCl portion in PCM slightly decreases the specific heat capacity. Experiment results showed that PCM-1 (eutectic salt with 30 wt% NaCl–70 wt% KCl) has the highest specific heat capacity, i.e., 6.93 J/g˚C. The highest rate of charging and discharging was exhibited by PCM-1, highlighting a positive effect of KCl content in eutectic salt.

Crankshaft is one of the main components of a combustion engine, and it is designed to be used for continuous rotation. Therefore, this study aims to analyze the crankshaft failure of a jeep with a four-cylinder diesel engine which was used to transport 4 tons of logs on rough terrain and uneven roads for 12 months. The process involved modeling the crankshaft with the initial defect followed by the application of the finite element method to determine the value and distribution of stresses occurring on the crankshaft and around the location of the initial defect. The stress values obtained were later used to calculate the stress intensity factor (KI), and the value obtained was compared with the fracture toughness (KIC) value. The simulation results and stress intensity factor (KI) calculated showed a concentration of stress in the area of the initial defect as indicated by the average value of the stress intensity factor recorded to be 293.13944 MPa √m from the simulation, while the fracture toughness of the material is 91.73 ± 3.34 MPa √m. This means KI > KIC at the crack tip, and this causes further propagation starting from the initial defect. The results simply showed that the crack propagation due to loading and the value of stress concentration at the crack tip area is the cause of the crankshaft failure. This is associated with the repeated loading characterized by beach mark patterns on the fractured surface.

In this study, there has been a failure of the crankshaft on a pick up vehicle using a diesel engine. After 3 months of use, the crankshaft broke on the crank arm. The purpose of this study was to determine the cause of crankshaft failure in a diesel engine pick up numerically. The crankshaft is modeled by using CAD to locate the initial defects in the crank web, then applying the finite element method to obtain the value and distribution of stresses that occur in the crankshaft and around the location of the initial defects. The results of the stress values obtained are then applied to calculate the stress intensity factor (KI) which will be compared with the fracture toughness value (KIC). From the simulation results and the calculation of the stress intensity factor (KI), it can be observed that there is a concentration of stress in the area of the initial defect. The amount of stress that occurs at the input in the value of the stress intensity factor is 91.827 MPa √m, while the fracture toughness of the material is 32.8934 MPa √m. The ratio of KI >  KIC at the crack tip causes crack propagation starting at the initial defect. Based on the results obtained, crack propagation due to loading and the concentration value at the crack tip area is the cause of failure of the crankshaft.

Wind energy is one of the energy sources that began to be developed to convert mechanical energy into an electrical need for the community. Indonesia is considered very worth developing wind turbines as power plants. The potential of wind energy in Indonesia reaches 9286 MW at an average wind speed of 5 m/s, based on data from the Indonesia Energy Outlook and Statistics 2004. In this study, what was discussed was related to the influence of the number of horizontal axis wind turbine blades on the rotation of the shaft. The model of the turbine used is a propeller-type wind turbine with variations in the number of blades 3, 4, 5, 6, and 7 made of meranti wood material (Shorea multiflora). Data collection on a wind turbine is carried out without using the load from the generator, then the data taken on measurements is only in the form of data on wind speed (m/s) and rotational speed (rpm). Data collection for 10 days, in the test of the wind turbine, was measured at an average wind speed of 1–6 m/s. The more blades on the wind turbine, the more rotation of the shaft will increase due to a large amount of wind that crosses the cross-sectional area of the blade. Horizontal axis wind turbine the number of 3–7 blades, getting the optimal number of blades, namely at the number of 5 blades produces a maximum shaft rotation of 1751 rpm when the wind speed is 6 m/s. In the wind turbine, the number of 5 blades obtained the optimal characteristic value of the wind turbine with a tip speed ratio of 6, and the power of the wind turbine (P $$\lambda$$ λ out) is 166.78 watts.

This study was conducted to determine the stress in sports car camshaft using the finite element method. The simulation was based on three conditions which include flawless, wear defects, and wear with initial defects such as early cracks. The results showed that the maximum normal stress in the model without defects was 7.8 MPa at the fillet area, while the stress in the worn model was 22 MPa. These values were below the material permit limit of 29.8 MPa. Meanwhile, the worn model with initial defects such as cracks had 252 MPa, and this exceeds the limit. It was also observed that the stress intensity factor at the crack tip was 17.9 MPa m1/2, and this indicates a propagation crack. Therefore, it was concluded that camshafts without defects or with wear and tear are safe to use, while those worn with defects such as cracks are not.

A failure in leaf spring usually causes a critical accident because of its importance in transport vehicles such as Dump Trucks. Therefore, this research aims to determine the cause of failure in the leaf spring of the Dump Truck suspension system using experimental and finite element methods. The experimental tests included visual observation of the fracture surface to determine the possibility of fracture or material failure based on the condition of the spring and an SEM test to observe the fracture surface condition of fractography. A hardness test was also carried out to adjust the properties of the spring material according to its standards, chemical composition test to determine the properties of steel, as well as microstructure test, which shows the structure contained in leaf springs. The stress and strain analyses were carried out by modeling components using Autodesk Inventor software. The finite element method analysis used FEMAP 2021.2 software on the maximum stress and strain received by the leaf spring. This was followed by calculating the stress intensity factor (KI) at several points at each end of the fracture. The average KI value obtained from the finite element method analysis was 101.3220059 MPa.m1/2, while the KIC value was 22 MPam1/2. This value met the requirements for fracture mechanics, namely KI ≥ KIC.

The helical gear in a off-road 4 × 4 gearbox was found to have failed on the surface. Therefore, this study aims to determine the factors causing this failure through the application of visual observation, hardness test, chemical composition test, microstructure observation, Scanning Electron Microscope (SEM) observation, and stress analysis. The chemical composition test showed that the gear material is classified as high carbon steel with AISI 1080 standard, the average hardness value was recorded to be 95.49 HRB which is slightly lower than AISI 1080, and the microstructure is pearlite and cementite. Moreover, the observation of the fracture surface showed some initial defects propagated to a brittle fracture, while the shear stress value was found to be 286.13 MPa which exceeds the allowable shear stress limit of 253.47 MPa. It was concluded that the helical gear failed due to the initial defects in the form of fine cracks and the fact that the shear stress value exceeds the allowable limit.

The efficiency of using fossil fuels for transportation is continuously improving. Increasing vehicle efficiency can be done by better internal combustion engine technology or a method of driving the vehicle itself. Eco-riding is a method of operating a vehicle with better fuel efficiency. This paper discusses how to go with eco-riding and compares it to regular driving. The vehicle being tested is a motorcycle with an eco-riding indicator onboard, and the test is carried out with a travel route within the city of Banda Aceh, Indonesia. The trial took ten days of testing with two different traffic options. The first trip is during rush hour, and the second trip is under regular traffic conditions. From the driving test on rush hour trips, the driving system following eco-riding got a 10.62% fuel reduction, while fuel use was 10.93% more efficient for trips in regular traffic. The driving pattern in this study has been demonstrated to reduce fuel consumption significantly.

This paper discusses the experimental analysis of the sound absorption coefficient and transmission loss of hybrid panels made of a multi-perforated panel (MPP) backed by a honeycomb structure with different material elasticities. The panels are created using 3D printing and made of thermoplastic polyurethane (TPU) filament, which is more flexible than the second material, polylactic acid (PLA) filament. This study aims to compare the effect of material flexibility on the panel’s acoustic properties. The acoustics are measured using a four-channel impedance tube following ASTM E2611-19. The panels have various panel thicknesses, honeycomb wall and MPP thicknesses, and MPP hole densities. The study indicates that as panel thickness increases, the peak of the sound absorption coefficient is shifted to a lower frequency, resulting in enhanced sound insulation. When MPP hole density decreases, the number of MPP holes decreases, and the absorption coefficient and sound insulation increase. Furthermore, TPU panels have a lower sound absorption frequency than PLA and slightly higher insulation than PLA. As a result, material flexibility does not significantly affect the maximum sound absorption coefficient and sound transmission loss; more flexible panel material shifts the sound absorption coefficient peak to a lower frequency.

Cellulose nanocrystals, a class of fascinating bio-based nanoscale materials, have received a tremendous amount of interest both in industry and academia owing to their unique structural features and impressive physicochemical. This nanomaterial is a promising candidate for applications in fields such as biomedical, pharmaceuticals, electronics, barrier films, nanocomposites, membranes, supercapacitors. Nanocellulose has the disadvantage of being hydrophilic. The purpose of this study was to characterize nanocellulose from Pennisetum Purpureum fiber that had been given silane treatment. The isolation and characterization of nanocellulose from Pennisetum Purpureum were carried out. Chemical pretreatment has included alkali treatment which used 10% NaOH for 35 min and 60 °C temperature. Bleaching process with 12% NaOCL for 24 h and acid hydrolysis with H2SO4, 45 °C, 60 min will disperse amorphous part of cellulose. The silane treatment was carried out by soaking and heating the fibers at a temperature of 50 °C for 2 h using APTES (3-aminopropyl-triethoxy) and methanol with a ratio of 9:1. The mixture was centrifuged until neutral pH was obtained. The obtained suspension was sonicated (Branson Sonifier 450) for 5 min with an 800 W and freeze-dried to solid NCC. Based on the fiber characterization, alkali and bleaching pretreatment conditions showed that the surface impurities on the fiber were removed, and peak at 1058 cm−1 for C–O–C pyranose ring vibrations indicates the extensive cellulose exposure. The most significant finding from moisture content on dried samples after dialysis showed that nanocellulose only contains ± 1% moisture. These results indicate that Pennisetum Purpureum could become a viable source of commercially valuable nanocellulose.

Compact-type heat exchangers are widely used in industry because of their small dimensions and lightweight with high heat transfer rates. This study aims to examine the effect of straight-section length on a serpentine tube heat exchanger with sharp turns. The heat exchanger used is made of galvanized pipe with an inner diameter of 20 mm and an outer diameter of 22 mm. The total length of the heat exchanger is 6 m with variations in the length of the straight section, namely 60, 45, 30, and 15 cm. Water with a temperature of 80 ℃ is flowed into the heat exchanger using a pump that is integrated with the heater. The flow of water entering the heat exchanger is 0.4 L/s. Water at room temperature is used as a cooling medium for the heat exchanger. The inlet and outlet temperatures of the heat exchanger were measured using a thermocouple, and the cooling water temperature was also measured using a thermocouple. The results showed that a heat exchanger with a straight-section length of 30 cm had the highest heat transfer rate and heat transfer coefficient compared to other heat exchangers. The rate of heat transfer in a heat exchanger with a straight-section length of 30 cm is 15.9% higher than that of a heat exchanger with a straight-section length of 15 cm, 56% higher than the heat exchanger with a straight-section length of 45 cm, and 78.5% higher than the heat exchanger with a straight-section length of 60 cm. The highest convection heat transfer coefficient is obtained in a heat exchanger with a straight-section length of 30 cm, and the average heat transfer coefficient is 1168.5 kW/m2·K.

The development of wireless and microelectronics technology has led to wearable devices where power can be supplied by batteries as well as energy harvesting devices. Despite the advancements made by low-power microdevice technology, the power requirements to apply them are still difficult to find. For this reason, developing new energy harvesting techniques is necessary to maintain self-powered systems. Energy harvesters are also needed as an economically practical alternative to battery charging and reducing greenhouse gas emissions and preserving the environment. One of them is by using piezoelectric-based energy harvester techniques by utilizing rotation. The purpose of this study is to examine the influence of magnetic force direction on the voltage and efficiency produced by piezoelectric-based energy harvester mechanisms using magnetic lighters. In this study, there are two variations of magnetic circuits, the first is that the magnetic circuit is regulated to repel each other (Type A), and the second is the magnetic circuit is regulated by mutual attraction and repulsion (Type B). Data collection is carried out on an energy harvesting mechanism whose piezoelectricity amounts to 4 pieces with a variation of 1000 rpm. The efficiency produced by the Type A magnetic circuit is 0.278% with a resistance of 9780 ohms. The resulting efficiency of the Type B magnetic circuit is 0.460% with a resistance of 9760 rpm. The application of piezoelectric-based energy harvesting mechanisms is more effective when using Type B magnetic circuits.

Temiki (Melastoma Candidum) is one of the unutilized wild plants observed to be turning pests on plantations. It has only been used for medicine and not for engineering purposes. Therefore, this study aims to identify and analyze Temiki’s chemical compounds, which are useful as corrosion inhibitors. The plant was washed, dried, then blended until it became a fine powder, and was further extracted by employing the maceration method with ethanol as solvent. The extracted compounds were also analyzed using Gas Chromatography-Mass Spectrophotometry (GC–MS) and the results obtained include, 2-Furancarboxaldehyde (CAS) Furfural, 1,2,3-Propanetriol (CAS) Glycerol, Acetic acid,1-(2-methyltetrazole-5-yl) etheny, 4H-Pyran-4one,2,3-dihydro-3,5-dihydroxy, 5-Hydroxymethylfurfural, cis-dimethylmorpholine, 3-penten-1-ol,2,2,4-trimethyl-(CAS)2,2,4, 2-AMINO-9-(3,4-DIHYDROXY-5-HYDORO, D-Allose, beta-D-Glucopyranoside, methyl, Hexadecanoic acid, methyl ester, 9,12,15-Octadecatrienoic acid, methyl ester. In conclusion, these chemical compounds were useful as corrosion inhibitors.

Welding is one of the oldest joining processes to combine two materials. One of the commonly used welding processes is the tungsten inert gas (TIG) welding. In this study, Aluminum Alloy 5083 H116 is joined using TIG welding. Aluminum Alloy 5083 H116 is chosen because it is a popular material widely used in the industry, thanks to its properties such as good corrosion resistance, resistance in extreme environments, and high impact strength. The welding process of Aluminum Alloy 5083 H116 was performed under several speed variations, which are 1.8, 2 mm/s, and 2.2 m/s. We studied the effect of the welding speed on the mechanical strength and microstructure of the welded joint. The results are that the maximum tensile and bending strength were observed at a speed variation of 1.8 mm/s with a value of 286.75 and 485.19 MPa, respectively, and that the smallest tensile and bending strength values were obtained at a speed variation of 2.2 mm/s with a value of 204.65 MPa and 366.70 MPa, respectively. A good microstructure was attained in the weld joint for a speed variation of 1.8 mm/s.

The aim of this research is to investigate the polarization behavior of corrosion on the SA-179 material, which is commonly used in heat exchanger equipment. The existence of tube components as a conduit for cooling fluid such as water or other solutions is the most significant feature of the temperature control of the heat exchanger. The cooling media is frequently a corrosive solution, which may degrade the heat exchanger material's performance. Furthermore, the corrosion process could be accelerated by residual stress generated by the shape of the heat exchanger tube formed by the cold working procedure. The SA-179 Carbon Steel Material, which has been manufactured to represent a heat exchanger tube, metallographic observations, polarization measurements, and macro-observations on the surface of the corroded area have been carried out in this work. To produce the strain and residual stress conditions seen in the elongation and compression segments, the SA-179 material was loaded using the U-Bend method. To generate a corrosion polarization curve that describes corrosion behavior under the conditions of plastic strain and residual stress, the potentiostatic measurement has been applied. Plastic deformation has an effect on grain boundary conditions in the SA-179 material, according to the average grain size discovered in this work. The polarization behavior is also influenced by this circumstance. The corrosion potential value is − 0.766 V at a current of 1.9 × 10–7. A in the absence of strain and residual stress. Furthermore, the corrosion potential is demonstrated to be − 0.823 V at a current of 6.8 × 10–7. A under conditions with U-Bend deformation. According to this phenomenon, plastic deformation has a bigger Nobel effect on SA-179 material in a corrosive environment, but has a higher corrosion rate if the corrosion process has already occurred.

This paper experiments with stainless-steel AISI 316L substrate pre-treatment techniques in preparation for hydroxyapatite (HAp) flame spray coating. The mechanical, chemical, and combination pre-treatments were compared for the coating thickness and layer adhesion of the HAp to understand the influence of roughness on the layer adhesion of the flame-sprayed HAp layer on the flat substrate. The heat treatment at 800 °C for 1 h with 160 °C/h heating and cooling rate was conducted after spraying. Phase identification by XRD analysis shows that the substrates were partially coated with amorphous HAp. All pre-treated specimens have coating thickness that complies with medical requirements. Sandblasting creates the best hydroxyapatite layer coverage due to the highest surface roughness. On the other hand, the acidic immersion with sulfuric acid lowered the roughness value and caused the hydroxyapatite layer to have poor adhesion.

To ensure infrastructure resilience, regular assessment of infrastructure damage must be carried out. To assess hidden corrosion in reinforced concrete structure, inverse analysis can be employed. Inverse analysis combines partial field data and computational analysis, including machine learning. In this paper, Bayesian optimization was used for inverse analysis to find hidden corrosion in a reinforced concrete corrosion. A simple case study was presented where the hidden corrosion location was known. The partial data on the surface of the concrete was known and used for the inverse analysis. The Bayesian optimization was successfully used to find the location of the hidden corrosion. The Max Expected Improvement acquisition function performs better than Max Probability Improvement one.

Recently, natural and synthetic fiber reinforced composites may find application in nearly every sector of engineering. In this study, an experimental analysis of the dynamic features of jute fiber reinforced polymer composites (JFRPC) and glass fiber reinforced polymer composites (GFRPC) for the purpose of estimating Young's modulus is presented. The natural frequency value of composite plates made by JFRPC and GFRPC was measured using impulse excitation technique (IET) experiments. The tensile test, however, was carried out to verify the IET test's results. The findings indicate that the strength of a composite made of glass fibers is noticeably better than that of a composite made of jute fibers. However, the mechanical properties of woven jute composite are equivalent to those of glass fiber composite. This is especially true in regard to its Young's modulus, which is almost identical to that of the glass fiber composite. It is anticipated that this method will be able to predict the mechanical characteristics of other materials and that it will have potential as a non-destructive examination method.

Leaf springs are a type of spring designed to dampen vibrations caused by loading such as lateral loads, shock loads, and torsion. Due to the main role of this component makes its failure can directly cause a serious accident. This study aims to determine the cause of leaf spring failure in the 110 PS dump truck vehicle suspension system carried out by numerical and fracture mechanic approach. Numerically, leaf springs with initial defects were modeled using the finite element method software called FEMAP to find the value and the stress distribution that occurs in the leaf spring around the location of the initial defect. By fracture mechanics approaching, the stress results obtained are used to calculate the value of the stress intensity factor (KI) which is then compared with the value of crack toughness (KIC). Based on the results of stress simulation and calculation of stress intensity factor (KI), it was found that the stress that occurs is below the yield stress of the material and (KI) ≈ (KIC). From the results obtained, the study found that crack propagation was the cause of the leaf spring failure that occurred from the location of the initial defect. This failure occurs by the fatigue mechanism caused by repeated loading.

An excellent example of plant-based fiber used for noise reduction is Calotropis gigantean (CG). This research aimed to determine the sound absorption coefficient (SAC) value and sound reduction ability of the CG fiber. The fiber was coated with 0.3 mm thick aluminum and perforated with 1, 1.5, and 2.5 mm diameters. Furthermore, Bruel & Kjaer’s Type 4206 impedance tube with a diameter of 100 mm and a thickness of 10 mm was used as the model for the test sample. The sample, which weighed 50 g, was hot pressed in a mold for 10 min at 200 °C, and the test was conducted following the ISO 10534–2 transfer function method using an impedance tube at a frequency of 1/1 octave. The results showed that the test sample without aluminum coating can reduce the SAC by 0.05–0.1 (5–10%) compared to those coated with perforated aluminum. This is because the aluminum surface area is larger than the total hole area that transmits sound to the test sample, so more sound is reflected. Lastly, the uncoated sample’s noise reduction coefficient (NRC) value was larger than that of the coated sample and reduced the overall noise by 28%. This proved that the aluminum hole's diameter affects the noise reduction coefficient. The coated sample can be categorized into two classes, class D for uncoated samples and class E for aluminum coated.

The rear leaf spring of the light truck diesel vehicle tends to experience failure when passing through a potholed road carrying a load of 11,000 kg. Therefore, it is necessary to determine the factors responsible for these failures using experimental and numerical studies to prevent the reoccurrence of similar cases. The experimental study includes visual inspection to determine the factors responsible for the breakdown based on the surface condition of the broken spring. This is in addition to using SEM observation to observe the fracture surface condition of fractography and the hardness test to evaluate the hardness value of leaf spring. To visualize the structure, a chemical composition test is employed to analyze the steel standard and microstructure observation. Meanwhile, the numerical study includes leaf spring modeling using Autodesk Inventor software, FEMAP 2022.1, and stress analysis. The chemical composition test showed that the leaf spring material complies with the AISI 5160 standard. The visual inspection consists of an initial crack, which is then observed on the SEM. The average hardness of the horizontal and vertical directions is 114.05 and 113.40 HRB, while for the outer surface, it is 114.36 HRB. Based on the observation, the structure of the pearlite phase is less than the ferrite, indicating that the leaf spring has more ductile properties. The stress intensity and toughness factors are 77.99 and 22 MPa m1/2, respectively. Therefore, the calculation results have fulfilled the equation (KI ≥ KIC).

Material science has shaped the development according to the civilization since the mankind has survived. Composite materials are being used nowadays where less weight, high mechanical performances, resistant to fire, water and chemical resistant, excellent damping, fatigue and other properties are essential. The role of composite materials is significant in more promising areas like aerospace, automotive, constructions even if they have some disadvantages like high cost, high density and huge weight. In this work, a hybrid composite is prepared using bio-based fibres such as ramie, areca and sisal as these bio-reinforcements are eco-friendly, renewable and excellent strength. Mechanical parameters like tensile, compressive, flexural and impact strength are measured to check its suitability to replace the conventional materials.

The effect of welding parameters on the mechanical properties of weld joints of dissimilar metals (dissimilar metals) between Armour steel and ASS 304L stainless steel greatly affects the quality of the welds. This research was carried out by the GTAW process with a variation of the welding current at 100, 110, and 120 A. Mechanical properties of welded joints were analysed including tensile testing and hardness testing, to determine the strength of the welded joint and the distribution of hardness in the heat-affected area (HAZ). The highest hardness test value was found in the 110 A specimen, which is 527.6 HV in the HAZ Armour area, and there is a correlation to the tensile test results that the fracture occurs in the area of low hardness. The results of the highest tensile strength test were found in the 110 A current specimen at 626,154 MPa with a yield strength of 406.779 MPa. The fractures for all specimens occurred in the fusion line region towards ASS 304L. The welding parameters appropriate for welding dissimilar steel between Armour steel and ASS 304L can be used as a reference for welding military transformation tools and reducing production costs.