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Energy-saving and emission reduction are crucial since shipping activity due to the global maritime trade has increased exponentially. Several agreements have been engaged to optimize ship energy efficiency composed of ship design and shipping operation planning. However, most up-to-date studies focused on speed and route optimization. The interaction analysis between speed and route efficiency below varied environmental conditions is limited. To attain energy and cost efficiency, a study of cavitation on the propeller that considers the ocean environmental condition will be discussed in this work. Although researchers have previously observed cavitation phenomena, the predictability of simulations is not yet such that problems can be eliminated. Since the multiphase flow of water and vapor is sensitive to environmental conditions, it leads to varying observation accuracy. Thus, the current paper proposes a new performance indicator of the ship propeller under cavitation predicted by computational fluid dynamics (CFD). CFD-based simulation to observe the propeller cavitation was used to model the Zwart cavitation and Kunz cavitation models under two turbulence models of K−ε at different flow conditions and operating environments. Initial validation tests between experimental and numerical simulation show good agreement with a mean error of 4.7% in the Zwart model and 3.7% in the Kunz model, where the k−ε turbulence model provides an almost higher relative error. It is revealed from the result that the increase in temperature causes the rise in the cavitation problem. It is revealed from the result that the increase of temperature causes the increase in cavitation problem.

This paper presents a numerical procedure based on the finite element (FE) method using ANSYS Workbench software to analyse fatigue phenomena in ship structures. Fatigue failure prediction is used as a stress–life approach, when the stress is still in a linear area. This condition is frequently referred as high-cycle fatigue. Five geometric shapes taken from midship points on the structure of a ship are sampled. There are four types of materials: HSLA SAE 950X, medium-carbon steel, SAE 316L, and SAE 304L. The types of loading imposed on each sample include three conditions: zero-based, zero mean, and ratio. Mesh convergence analysis is conducted to determine the most effective mesh shape and size for analysing the structure. The results showed that the configuration of the geometric shapes, materials used, loading schemes, and mean stress theory affect the fatigue characteristics of the structure.

The development of the global economy has led to a rise in ship traffic. As a result, the risk of accidents, such as collisions between ships and grounding, has also increased. Different failure criteria to capture these accidents have been introduced by researchers. Therefore, the purpose of this study was to determine the essential distinction between these failure criteria. The simulations suggest that failure criteria based on the maximum stress result in a slightly higher rupture strain value, greater crack propagation, and higher internal energy than those based on the maximum strain. Furthermore, using a larger mesh size compared with the size of the test specimen appears to greatly affect the validity of the simulation results.

The shape of the projectile seems to determine the effect of a ballistic impact and failure mechanism. In this study, the numerical analysis of ballistic impact with different projectile shapes, i.e., ogive, blunt, conical, and hemispherical is performed. The target is a circular sandwich plate with an outer diameter of 315 mm, which is composed of three layers with a thickness of 1 mm for each layer. These layers will be filled with different materials such as 1100-H12 aluminum alloy, ZK61m magnesium alloy, and 6061-T651 aluminum alloy. The target plate in the numerical analysis consists of two parts: the inner and outer zones. In the inner zone, the selected element size is set to fine, while in the outer zone, it is set to be coarser, and the size will increase along with the direction and the diameter of the circle. This numerical simulation uses the Johnson–Cook material model and is applied to ABAQUS/Explicit software. The simulation configurations are validated based on previous experiments by comparing the residual velocity values after the projectile has penetrated the target plate. The simulation results will obtain energy absorption values for each variation of the target plate. The energy absorption values are affected by stress and strain in radial, circumferential, axial, and shear deformation. The energy absorption value determines the strength of each variation of the target plate. Then the target plate will compare which arrangement is the strongest when receiving ballistic loads.

Background The problem of ballast water is caused by microorganisms. The solution to solve this problem is ballast water disinfection. Until the recent day, there have not been many practical solutions. Usually, ozone, chlorine, and UV treatments were used for disinfection. However, these methods still have many weaknesses in treating ballast water. Methods The ferrate(vi) system proposed in this paper is liquid ferrate(vi) produced on-site using a slow-released system and combined with ultrasound. This paper investigated the optimum time to produce liquid ferrate(vi), pH, and temperature. Results The optimum synthesis time has been observed to be 10 min with the produced ferrate(vi) of 42,000 ppm. The optimal pH and temperature to make ballast water harmless have been observed to be the neutral pH condition at 25°C, respectively. The design of ballast water treatment using ferrate(vi) combined with ultrasound has also been proposed in this paper. Conclusions Ferrate(vi), as the primary material in ballast water treatment, has been successfully synthesized. The process of ballast water treatment using ferrate(vi) combined with ultrasound can be performed automatically using a time sensor and a mass sensor. With the proposed design, it can be a promising solution to solve the problems related to ballast water.

Rim wheel testing through the SAE standard is necessary for driving safety. This study focused on rim wheel tests carried out using the dynamic radial fatigue test method, which has been included in the SAE standard using Fusion360 for the design and ANSYS for the simulation. With different parameters for the rim wheel type, only some parameters of the tested rim wheels were able to pass the standardization by SAE; 16 rim wheels passed the test, while the other 11 rim wheels did not pass. Simulation results suggested that variations in the thickness, geometry, and material affected the displacement of the safety factor, which was inversely proportional. In addition, the variation in the rim wheel produced a change in the safety factor due to changes in its mass and cost, which were directly proportional. The results of this study will aid in rim wheel design, not only in terms of achieving the best performance but also with regard to cost efficiency.

In this article, the load resistance and energy absorptions of thin-walled structures on the square tube were numerically evaluated by the finite element method. This structure can be widely used in automotive industries, industrial buildings, ships, offshore platforms, and airplanes. In the finite element method, thin-walled structures on square tubes were examined with different wall thicknesses and materials. The materials used are mild steel, SAE 1045 steel, and SAE 1008 steel. Using the numerical results, the thickness of the wall influences the strength of the structure. Moreover, SAE 1045 steel material also seems to increase the strength of the tube under axial loading compared to the mild steel and SAE 1008 steel material. It is also important to remember that the finite element solution depends on defining your mesh size and boundary conditions. The mesh size is also compared and assessed.

Purpose This article aims to investigate the structural behavior of beam–column joints subjected to axial force. The geometry used is the addition of a number of beam connections to the column, and the differences in the numbers of beams used are 1, 2, 4, and 4, denoted as V1, V2, V3, and V4, respectively. Design/methodology/approach In this work, the analysis was performed using the numerical finite element method with ABAQUS software. A benchmarking analysis was also conducted to validate the numerical results. Findings Several numerical simulations showed that of the variations tested, the V2 model demonstrated the highest force value among the four test models, at 130.883 kN. The displacement caused by the force was 227.32 mm, which was the lowest value among the four test models. On the other hand, the V3 model received the smallest force value among the four test models, at 24.576 kN, with a displacement of 227.49 mm. The displacement value was greater than that for the V2 model, further indicating that the V2 model was the stiffest of the four models tested. Originality/value This study shows that the influence of beam–column joint geometry is not limited to double-extended end-plate bolted connections.

The use of technology in everyday life is unavoidable, considering that technological advancement occurs very quickly. The current era is also known as industry 4.0. In the industry 4.0 era, there is a convergence between the industrial world and information technology. The use of modern machines in the industry makes it possible for business actors to digitize their production facilities and open up new business opportunities. One of the developments in information technology that is being widely used in its implementation is machine learning (ML) technology and its branches such as computer vision and image recognition. In this work, we propose a customized convolutional neural network-based ML model to perform image classification technique for Indonesian herb image dataset, along with the detailed review and discussion of the methods and results. In this work, we use the transfer learning method to adopt the opensource pre-trained model, namely, Xception, developed by Google.

Thin-walled structures, which generally consist of unstiffened and stiffened plates, are widely used in engineering as one of the core features of any product or construction. Due to environmental conditions and working operation, the components of the structure unavoidably become subject to various types of loading. Deformation patterns and overall behaviour are expected to be varied, as different materials are considered in the structures. In this situation, assessments are required to quantify the responses and determine the relationships between the structural behaviour and structural parameters. In this work, we attempt to obtain the behaviour data of unstiffened and stiffened plates as components of thin-walled structures. The material class – i.e. low- and medium-carbon steels – and loading parameters (i.e. type and angle) are taken as the main inputs in the finite element analysis. A geometrical design is adopted based on the side hull structure of a medium-sized tanker, for which two plate types, unstiffened and stiffened, are used. The results indicate that increasing the loading angle reduces the force experienced by the plate, while the greater the loading direction angle is, the greater the total displacement value will be. In terms of the plate design, the stiffener is observed to reduce the force expansion during the loading of the stiffened plate.

Underwater wet welding (UWW) is widely used in repair of offshore constructions and underwater pipelines by the shielded metal arc welding (SMAW) method. They are subjected the dynamic load due to sea water flow. In this condition, they can experience the fatigue failure. This study was aimed to determine the effect of water flow speed (0 m/s, 1 m/s, and 2 m/s) and water depth (2.5 m and 5 m) on the crack growth rate of underwater wet welded low carbon steel SS400. Underwater wet welding processes were conducted using E6013 electrode (RB26) with a diameter of 4 mm, type of negative electrode polarity and constant electric current and welding speed of 90 A and 1.5 mm/s respectively. In air welding process was also conducted for comparison. Compared to in air welded joint, underwater wet welded joints have more weld defects including porosity, incomplete penetration and irregular surface. Fatigue crack growth rate of underwater wet welded joints will decrease as water depth increases and water flow rate decreases. It is represented by Paris's constant, where specimens in air welding, 2.5 m and 5 m water depth have average Paris's constant of 8.16, 7.54 and 5.56 respectively. The increasing water depth will cause the formation of Acicular Ferrite structure which has high fatigue crack resistance. The higher the water flow rate, the higher the welding defects, thereby reducing the fatigue crack resistance.

In the field of logistics, containers are indispensable for shipments of large quantities of goods, particularly for exports and imports distributed by land, sea, or air. Therefore, a container must be able to withstand external loads so that goods can safely reach their destination. In this study, seven different models of container skins were developed: general honeycomb, cross honeycomb, square honeycomb, corrugated wall, flat, flat with a single stiffener, and flat with a cross stiffener. Testing was performed using the finite element method. In the static simulation, the best results were obtained by the model with corrugated walls. As the main element and the content of the sandwich panel structure, the core plays a role in increasing the ability of the structure to absorb force, thereby increasing the strength of the material. In the thermal simulation, the best results were obtained by the general honeycomb walls. Vibration simulations also showed that the square honeycomb design was better at absorbing vibration than the other models. Finally, the corrugated model had the best critical load value in the buckling simulation.

The assessment of a ship's ability to withstand environmental loads is very crucial. This research focuses on the strength assessment of 600 TEU container ship hulls against hydrostatic and hydrodynamic loads using finite element-based software. Parameter changes in the material types, hull thickness, and ship drafts were performed to compare the structural responses using deformation, strain, and von Mises stress criteria. All of the materials tested were acceptable, where the ASTM A131 Grade AH36 and ASTM A131 Grade AH32 materials have the lowest deformation values and strains. The simulation results regarding plate thickness variation, deformation, strain, and von Mises stress values were smaller as the thickness of the ship structure increased. Moreover, from the draft variation, the structural response due to environmental load was better as the draft of the ship increased.

This work aims to investigate the mechanical behavior of steel-plated structures under a raking incident and to quantify the effect of the mesh size in nonlinear finite element (NLFE) analysis. To conveniently comprehend nonlinear phenomena, i.e., the grounding which takes place in this work, a series of theoretical contact formulations was defined. In the main analysis, raking, which is a part of the grounding scenario, was strictly assumed as contact between a tanker, which was assumed to have thin-walled steel, and a seabed rock in the form of a solid obstruction. Designed raking scenarios were calculated using the FE method by using the nonlinear phenomena of the material behavior in the calculation. The findings of this work indicated that the possibility of expanding the recommended mesh size in FE simulation should be evaluated by quantifying the behavior of structural responses, such as energy, the force damage pattern, and acceleration, subjected to a variety of applied meshing techniques. The results concluded that a notable difference occurred when the mesh size was more than 132 mm (ratio 11 based on the plate dimension in this work), and this size is strictly recommended to be used for calculation of the element length-to-thickness (ELT) ratio. Assessment in time simulation showed that applying larger mesh sizes will reduce the simulation time but increase the maximum values of the crashworthiness parameters, i.e., energy, force, acceleration, and displacement.

This study aimed to compare the graphical method (GM) and standard deviation method (SDM), based on analyses and efficient Weibull parameters by estimating future wind energy potential in the coastline region of Dar es Salaam, Tanzania. Hence, the conclusion from the numerical method comparisons will also determine suitable wind turbines that are cost-effective for the study location. The wind speed data for this study were collected by the Tanzania Meteorological Authority Dar es Salaam station over the period of 2017 to 2019. The two numerical methods introduced in this study were both found to be appropriate for Weibull distribution parameter estimation in the study area. However, the SDM gave a higher value of the Weibull parameter estimation than the GM. Furthermore, the five selected commercial wind turbine models that were simulated in terms of performance were based on a capacity factor using the SDM and were both over 25% the recommended capacity factor value. The Polaris P50-500 commercial wind turbine is recommend as a suitable wind turbine to be installed in the study area due to its maximum annual capacity factor value over 3 years.

Consumer awareness of the adverse biological effects of synthetic dyes makes the demand for commercial foods and drinks with natural ingredients increase. The use of natural dyes is increasing and is in demand by consumers in the industrial world. Natural dyes have been used in several sectors such as food, clothing, arts, coatings, and energy. The low stability and brightness of the natural red color are affected by exposure to light, temperature, pH and etc. The co-pigmentation process makes the stability and brightness of natural dyes. The copigmentation method is known that there are two type, liquid and powder. In addition, the combination of copigmentation additives and the correct configuration of the spray dryer process can increase quality color fastness and stability.

Hip joint is an important human joints system. The damaged hip joints need to be replaced with artificial hip joints. The Study of the hip joint is very costly therefore another calculation method is demanded to produce good result in acceptable time and cost. Considering this problem, a series of study to assess hip joint performance is conducted using numerical approach. Important parameter for example applied materials are used in the modelling by idealizing Ti-6Al-4V compared to SS 316 L, and stemlengthwas chosen to be 128 mm. ANSYS software was used to analyze models, and designed element size variations were set to be in range 1 to 2.5 mm. The magnitude of force was placed on the femoral head with an angle of 16 ∘ C from the vertical axis. Results showed that SS 316 L material has smaller deformation than Ti material. Whereas Central Processing (CP) time decreases in increasing element size for both materials. In addition, more variations in mesh size are needed to get more accurate convergent results.

Remarkable consequences of maritime accident can be various, including structural damage, loss of life and marine pollution. During an accidental phenomenon, such as ship grounding, the amount of oil spillage indicates casualties’ extent of surrounding sea water. Effort to provide protection for sea environment against such event has been conducted actively by developing navigational instruments, and passively using structural development and assessment. The accidental grounding is, however, a very complicated process with high sensitivity to given factors during its occurrence. Variety in ship type, location, obstruction etc. affected by advance improvement in naval technology, invites sustainable analysis for structural crashworthiness and failure to produce evaluation data. This work aims to perform an assessment on double hull tanker subjected accidental grounding with oceanic seabed as the obstruction. Fundamental concept of bottom raking is used to design grounding scenario using numerical experiment. Non-Linear Finite Element Method (NLFEM) is deployed to idealise tanker structure and obstruction geometry. The selected crashworthiness criteria in grounding are summarised to provide structural prediction in moment double hull members are experiencing crushing process. Influence of geometrical parameters’ variation to progressive failure is presented with contribution of double bottom members to structural behaviour in final part. Result data of the current work can be a reasonable reference to understanding double bottom performance in grounding, especially in raking case. Insight of such accidental phenomenon is very useful in further effort to minimise grounding consequences.

During ship collision, hull crashworthiness is an important data which needs to be assessed as rapid development of hull structure has taken into consideration since several notable dangerous events. After catastrophic accidents cause both tragic loss of life and destruction of maritime environment, double skin system is applied for almost all ships, including RoRo passengers. This work aimed to assess effects of selected internal parameters to crashworthiness criteria, considering a passenger vessel as the target of a series of impact loads. A set of collision scenario was numerically designed using finite element (FE) method by involving single and double skin structures, target location and material grade to obtained estimation of hull crashworthiness. Assessment was focussed on the energy absorption, crushing force, stress level and failure strain of the target ship after experiencing side collisions. It was obtained from the analyses regarding role of the inner skin on tendency of the energy absorption. Failure progress on the proposed structures was successfully quantified based on stress expansion. Minimum value of material strength was concluded in final discussion to reduce more massive failure.

The main goal of the present paper was to study the physical response of a double side skin (DSS) structure under impact load in a collision event between two ships. Collision energy and damage extent (size and location) during the collision process were observed together with damage patterns on side structure. The ships were modeled after a Ro-Ro passenger ship and cargo reefer which were involved in a ship collision on the Sunda Strait while the analyseswere performed using non-linear simulations FEMto produce virtual simulation data. Several caseswere proposed to be investigated in this work with involvement of parameters i.e. penetration location and ship materials which were embedded on the structure model. A series of material experiments and testing was conducted to obtain detailed material properties which were to be deployed in simulation. It was shown that, after penetration at the transition location, the striking ship was successfully deforming and forming tears to the inner skin. On the other hand, with identical structure and identical mass of construction, the use of high-strength low-alloy (HSLA) steel as the repair material offered considerably better capacity in absorbing the impact load than plain-carbon steel.