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Today, most of the essential energy needs of humans and production are met by fossil fuels that are expected to be exhausted in the next century. Furthermore, fossil fuels are not renewable and sensitive to the environment. In particular, there is growing concerned about the negative impact of internal combustion engine emissions on climate change and global environmental pollution. Fuel and alcohol-based additives are being considered as good candidates for sustainable alternative fuels used on compression ignition engines. In this review, the different key production pathways and properties of each of the five alcohol additive candidates were discussed. Besides, their effects on the emission characteristics of diesel engines when alcohol additives are added to diesel fuel are also carefully considered. Five candidates including methanol, ethanol, propanol, butanol, and pentanol have been shown to control pollutants from combustion engines while using alcohol-based additives. This is of great significance in the strategy of coping with the threats of pollution and climate change caused by the operation of transport vehicles

The oil spillage and maritime pollution due to spilled oil have been affecting human life and the environment in the long term seriously. The methods and techniques presently used to recover oil sp...

Agricultural and agro-industrial residues are ordinary wastes in the forestry industry and their valorization is an important issue.Cocoa (Theobroma cacao) pods waste was chosen as an activated act...

The development and modernization of the industry are known to bring many benefits for the human life, to diversify the production process and to create the abundant products originated from differ...

Biodiesel has been emerging as a potential and promising biofuel for the strategy of reducing toxic emissions and improving engine performance. Computational methods aiming to offer numerical solutions were inevitable as a study methodology which was sometimes considered the only practical method. Artificial neural networks (ANN) were data-processing systems, which were used to tackle many issues in engineering and science, especially in some fields where there was a failure of the conventional modeling approaches. Thus, it was believed that the best choice was the development of a novel approach like the ANN model to anticipate engine performance and exhaust emissions with high accuracy. In this review paper, the structure and applicability of the ANN model were comprehensively evaluated. More importantly, the use of ANN with trained, tested, and validated data was introduced to determine the performance and emission characteristics of a diesel engine fueled with biodiesel-based fuel. In general, the ANN model could supply a relatively high determination coefficient as compared between predicted results and experimental data, showing that the ANN model could have a good ability to predict the engine behaviors with an accuracy higher than 95%.

In this paper, the results of an overview of the formation of carbon permeability when using a number of different permeable gases are presented. The most common permeable gases are “endo” gas and methanol. However, with conditions in Vietnam with an extremely abundant gas source, the use of imported gases will cause enormous waste. Therefore, in this study, we introduce the formation of the permeability medium of two “endo” and methanol gases. In addition, the authors also presented an analysis of the formation of seepage environments from Vietnamese gas sources. Research results show that the formation of permeability medium is suitable for imported gases. Experimental results show that the use of Vietnamese gas for permeability is of the same quality as imported gases.

Laser is considered one of the most influential inventions in the twentieth century and laser technology has been contributing in many areas of life. Today, in any field of manufacturing, laser technology also presents value and brings a range of specific benefits to the field such as machine manufacturing and mechanical tools. Thanks to the cutting edge cleaning ability, delicate welding lines, strong etching strokes, high power operation, accurate distance measurement capability, laser technology has gradually conquered and dominated the mechanical market, especially in the field of material handling, metal parts. Using lasers to cut metal creates highly detailed and continuous details, lines, shapes, patterns ... that open new avenues for the mechanical and machine-building industry. Using laser engraving machines, it will process complex and sophisticated details, saving time and manpower costs. High processing speed, smooth cutting surface and easy programming are the advantages that laser cutting technology offers to this industry. Lasers can be cut on different sheet metal or tubular surfaces at extremely fast speeds on tools, machine parts and even small-sized cutting workpieces. This paper will present an overview of laser technology and its common applications in the mechanical and machine-building industry. The analysis and evaluation in this paper will provide an update on the level of development of laser technology in the current industry age 4.0. In addition, it is a common picture and achievements of the machine manufacturing industry achieved with the support of "Light Amplification by Stimulated Emission of Radiation".

In this study, an equation for adjusting the parameters affecting the flare of the weld on the welding product was established. Based on the empirical research results, the factors affecting welding flux after using bending machines have been studied. It has showed that the factors like the press force, the welding mode, the welding current, and the welding time were the main factors afftecting directly the flaration of the weld. For the standard of the flare of the weld of 3.3 mm, the welding current was 22A, the welding time was 5 deci-seconds, and the press force was 2.78 Kg/cm2. The results showed that the automatic steel-wire welding after improving the welding machine and mode had a productivity of 5.8 times higher and reduced 20% of energy consumption compared to traditional welding methods. Compared with unmodified automatic welding, the productivity increased by 5.8%, energy decreased by 7%, and the weld quality was more stable.

The utilization of renewable lignocellulosic biomasses for bioenergy synthesis is believed to facilitate competitive commercialization and realize affordable clean energy sources in the future. Among the pathways for biomass pretreatment methods that enhance the efficiency of the whole biofuel production process, the combined microwave irradiation and physicochemical approach is found to provide many economic and environmental benefits. Several studies on microwave-based pretreatment technologies for biomass conversion have been conducted in recent years. Although some reviews are available, most did not comprehensively analyze microwave– physicochemical pretreatment techniques for biomass conversion. The study of these techniques is crucial for sustainable biofuel generation. Therefore, the biomass pretreatment process that combines the physicochemical method with microwave-assisted irradiation is reviewed in this paper. The effects of this pretreatment process on lignocellulosic structure and the ratio of achieved components were also discussed in detail. Pretreatment processes for biomass conversion were substantially affected by temperature, irradiation time, initial feedstock components, catalyst loading, and microwave power. Consequently, neoteric technologies utilizing high efficiency-based green and sustainable solutions should receive further focus. In addition, methodologies for quantifying and evaluating effects and relevant trade-offs should be develop to facilitate the take-off of the biofuel industry with clean and sustainable goals.

Selecting and optimizing propulsion architecture is one of the most practical goals and the most difficult decisions in designing modern commercial ships. That process faces several challenges, namely greenhouse gas emissions from the consumption of fossil fuels, IMO's strict international legal system on environmental pollution prevention, and new energy efficiency standards for design and management of commercial fleets. With the integration of electrical systems and power supply equipment in maritime transport in the past several decades, the availability of electric propulsion systems have brought several benefits to ship owners, including improved ability to comply with international laws, increased flexibility and reliability, reduced operating costs, and enhanced access to advanced automation capabilities. However, the introduced benefits of electrical and hybrid electric propulsion system architectures in recent years have put considerable pressure on ship owners and designers when optimizing the vessel’s propulsion and power system and their control strategies. This paper presents a comprehensive review of conventional and advanced electrical propulsion systems on current commercial vessels and future smart ships. By highlighting the characteristics of the propulsion system configuration, electric power source, and propulsors the authors present a detailed comparison and analysis in optimizing the choice of electric or hybrid powertrain systems for commercial fleets. Taking into account the increasingly stringent standards related to energy efficiency and emissions regulated by IMO, this paper also addresses strategies for the development of sustainable maritime transport by proposing the efficient use of renewable energy sources and electrical energy storage system.

In this study, an experimental investigation of the development of a thermoforming apparatus and the thickness uniformity of its samples was performed based on the axiomatic design theory in conjunction with the Taguchi method. Thermoforming is a powerful tool for both consumer product needs and packaging industry. Such traditional technology has been investigated in many aspects for a long time ago. However, there are still needs for the development and characterization of thermoforming devices aiming at shorter construction time and less cost involved. Therefore, an experimental analysis was performed to systematically realize all the functional structures of the device using axiomatic design theory. The combination of orthogonal array (OA) and analysis of variance revealed the influences of the relatival processing factors, showing that the thickness of the plastic sheet and areal draw ratio had crucial roles to play. Furthermore, an optimization process using the Taguchi method was utilized to determine all accurate and optimum processing parameters. The outcomes obviously verified that the present combination method can overcome the current development and optimization method’s limitation and also conclusively give accurate optimal outcomes without using complicated algorithms and software solutions. Therefore, it promises a simple and powerful tool for engineers on-site in medium or small scale manufactories.

Marine pollution due to spilled oil has become a major issue in the aquatic environment protection over the past decades. Externally, the spilled oil can penetrate animal feathers and fur resulting in decreasing the movement ability and the control ability of the body temperature of animals. When ingested, the spilled oil can also seriously affect the balance of the metabolism, the water retention. As a result, many kinds of animals were found to be killed by oil spills. Finding the effective methods for oil spill treatment is extremely urgent aiming to respond to incidents related to oil spill-recovery strategy. Among as-used methods including physical-, chemical-, biological-, thermal- and mechanical techniques, mechanical equipment showed the highest efficiency and rate of oil spill recovery. In this work, a type of mechanical equipment such as oleophilic skimmers was reviewed on the basis of the published study. The classification and the issues regarding technical parameters were introduced. Finally, impact factors such as weather conditions were mentioned.

In this work, the mechanical properties of AISI 1018 low carbon steel after been treated by different quenching media (water, boiling water, boiling salt water, ice water, ice salt water) were evaluated. The microstructure of the specimen was examined by using optical microscopy (OM), while the mechanical properties were evaluated by using tensile test and hardness test. The results of this investigation showed that improving in mechanical properties such as yield strength about 580 MPa, ultimate tensile strength about 680MPa and Vickers hardness about 263.03Hv for the specimen quenching by ice water, and the hardness for ice salt water 290.8 Hv. For ice salt water quenching media, the formation of martensite phase more than another quenching media, this is revealed obviously by microstructure examination. Also retained austenite exists in as a secondary phase as a result of very fast cooling for ice salt water quenching media.

In recent years, the development of world shipbuilding and shipbuilding technology has set new requirements for Vietnam Shipbuilding industry, which must be gradually developed on a par with the region and the world. This requires the domestic shipping industry to quickly apply advanced technologies, shorten construction time. At the same time, the training team of highly qualified technicians and workers can be trained to proficiently use new technological equipment. The study of modern specialized equipment for construction and assembly and centering on repair of the shaft system - the main engine of cargo ships is very important.. This article examines the features, specifications, usage of laser generator- Microgage 2D to effectively apply to the process of centering and assembling main engines and axles on ships. At the same time, research and design suitable jigs for microgage 2D applications in teaching practice at Shipyard engineers.

The search for technical solutions to optimize the combustion chamber size as well as improve the combustion efficiency of the scramjet engine has gained many benefits from optimizing the air-fuel supersonic mixing. Indeed, the technique of increasing the mixture through optimizing the flow of air-fuel mixture by applying cavity technology is the outstanding solution. This present work reports of a passive enhancement technique of supersonic mixing of air-fuel through amplification of cavity-induced flow field oscillations. In this study, with the controlling-edge profile changes to assess the changing properties of an unstable flow on a shallow cavity at the controlling-edge. This controlling-edge modification is used to augment the stimulating way in a shear surface, and that may lead to the amplification of cavity-induced flow field oscillations. The ‘reactingFoam’ solver within the OpenFOAM was used to simulate the supersonic cavity induced air-fuel mixing. The pressure changes over time with time and mixing indices at various positions of cavity are analyzed. Changing the leading-edge profile of the combustion chamber has an important impact on the pressure variation as well as the efficiency of the mixing process.

In a flow including a free surface, an interaction relationship between objects and the free surface is seen in many cases. In recent years, research on environmental change and protection has become active, so analyzing a flow field including the free surface is one of the major issues in river engineering and marine engineering. However, in most of the previous researches, the flow field was limited to the reproduction of the simple flow field. In this study, we dealt with the flow field including the free surface around a moving object with a complicated shape. So, in order to show the change of the shape of the free surface caused by the moving object, the Interface Tracking method was adopted. In this method, in order to express how the interface moves, it is necessary to move and deform the computational grid. Therefore, the calculation method was constructed based on the Unstructured Moving-Grid Finite-Volume method, which strictly satisfies the geometric conservation law and the physical conservation law. The NACA0012 blade was placed under the free surface, and the relationship between the blade's movement and the free surface was investigated. As a result, it was confirmed that the detail change of the free surface caused by the movement of the blade. Thus, it could be shown the promising feature of the computation.

Besides the model of farming on traditional natural land, with the goal of producing both specific products, high quality and high standards. Especially opening up opportunities to access the most advanced technologies in the world, the trend of investing in specialized trading houses for agricultural crop production is attracting investment for research and development. Greenhouse is one of the effective models in agricultural production in the direction of high technology. The cost of installing greenhouses is still quite high compared to the income of farmers, but the greenhouse is suitable for requirements for sustainable agricultural development. It allows full and strict control of most production process parameters such as temperature, light, humidity, carbon dioxide, oxygen, … It is necessary to optimize and homogenize the environmental conditions in plant factories. We installed sensors to observe the environmental factors in a plant factory and evaluated lettuce growth. We found that the integrated quantity of PPFD (Photosynthetic Photon Flux Density) is correlated with fresh weight of harvested leaf lettuces and that lettuce density also affects growth. There is the relationship between adjacent and central stocks.The authors are retracting this article because the methods, designs, and conclusions were copied from a previously published article [1]. The authors understand that taking credit for work that is not your own is a serious violation of publication ethics and the AIP Conference Proceeding’s policy. The authors apologize for any inconvenience this has caused.

Turbulent bubble flow applications for fluid engineering are becoming increasingly common. The horizontal movement of turbulent bubble flow in the vertical shear flow is considered to be the most important. With the goal of clarifying the mechanism of action of the turbulence on the lateral movement of an emerging bubble, a simulation model is proposed in this study to describe the motion properties of spherical bubbles in a homogeneous mixture under the influence of vertical shear forces. With the assumption that light solid particles are treated as surfactants, it may be those that cause the bubble to be contaminated. In this study, the submerged boundary method is used to represent a spherical bubble. At the same time, the authors have built a numerical model to directly simulate the motion of finite size bubbles to assess the effect of homogeneous shear disturbances on the horizontal movement of bubbles. The analysis of the numerical model shows that the finite-sized clean bubbles have the direction of horizontal traversal reversal in uniform shear motion. Comparing the results with those for contaminated bubbles, it is found that the transverse migration in the reversed direction is more pronounced for clean bubbles.

The development of the CNC machine and its advantages led to the constantly developing fields for this system, which are CAD (Computer-Aided Design) and CAM (Computer-Aided Manufacturing). However, surface issues were rarely mentioned in these studies, but mainly on tool path calculations or cutting modes. Reasonable selection of cutting tools, optimal tooling strategy for surfaces, and cutting mode parameters impact productivity and form quality of details containing complex surfaces. This study evaluates free surface based on Gaussian curvature and mean curvature, thereby providing a suitable instrument selection for the evaluated free surface areas. In this paper, the authors analyze and select tools and tool paths when machining freedom faces on 3-axis CNC machines to satisfy surface shaping accuracy requirements and reduce machining time related to the traditional freedom-face machining method. Before doing experimental research, the authors designed experimental samples on CATIA V5R20, simulating the machining process to verify the theoretical calculation. Empirical models for machining on 3-axis CNC milling machines were built and measured the parameters on 3-coordinate measuring machines to evaluate the effect of tool selection and tool paths in the machining of freedom surface areas. Experimental results show that the tool path when machining freedom surfaces dramatically affects the quality of freedom surface shaping. Moreover, the experimental results also show that when processing saddle-face samples, the one direction tooling path should be selected.

With the advantage of reducing the damage of bending stress up to 10%, the straight-toothed bevel gears (STBG) with a shoulder-bearing are being used in many industries automobiles, trains, mining, space, machinery technology and aviation equipment. With the working characteristics of straight-tooth bevel gear, the manufacturing quality assessments are usually conducted through micro-dimensional values, surface gloss, and internal surfaces' contact ability in the transmission. Recently, research and application of gear machining methods on 3-axis CNC milling machines are gradually becoming more popular. Therefore, the study of the affection of technology parameters on the quality of shaping the STBG surface by evaluating the output factors (surface undulation, micro-geometry parameters and trace contact size) in the finishing step is very urgent. First of all, the paper goes into detail in building design solutions to create input data for the machining of STBG on CNC milling machines by profile attachment method. Moreover, the study also built the process of evaluating the machining quality of the STBG utilizing microgeometry and the contact size. The paper focuses on developing experimental equations that show the relationship between technological parameters (S, F, Z) and roughness (Ra), deviation of tooth profile shape (f f ), and trace contact size (bc, hc) of the Z11-16 m8 STBG transmission. From that, the optimal technology solution was identified to ensure the contact accuracy when processing the Z16-11 m8 STBG transmission on a 3-axis CNC milling machine.

Today, humans are dealing with two urgent issues: energy security and environmental pollution and finding sources to replace traditional fuels such as gasoline and diesel that are part of human interest. Lignocellulose biomass can be obtained through a variety of basic chemicals or intermediates that generate energy, such as ethanol, butanol, and dimethylfuran. 2.5-dimethylfuran (DMF) is considered a potential alternative fuel because it is a water-insoluble substance used as an additive mixed with gasoline fuel. Formerly, there have been many studies on combustion engines and emissions properties using the DMF-gasoline blend, especially SI engines. However, there has been no published research about the optimal ignition timing advance of SI engines when using these blends. This paper present how to determine the optimal ignition timing advance of SI engines using DMF-gasoline combinations with AVL-Boost simulation software. The simulation conditions were set up at 50% load, and speed at 2500 and 3000 rpm using blends are DMF20, DMF30, and DMF40 (corresponding with the DMF ratio in DMF-gasoline blends is 20%, 30%, and 40% in volume). The simulation result shows that the optimal ignition timing advance of SI engines using DMF-gasoline blends at a 2500 and 3500 rpm speed corresponding with 23 and 31 crank angle degrees (CAD) (reduce 2CAD compare to when using pure gasoline). At these optimal ignition timing advances, the power engine, torque, and thermal efficiency (BTE) reach its maximum value, while the fuel consumption rate is also lowest.

This paper investigates a high electrical conductivity and high strength of alloys based on Cu-Ni-Si system It proclaimed the results of the effect of tin (Sn) component on the mechanical properties and microstructure of Cu-Ni-Sn alloy. The conditions for processing the Cu-Ni-Si alloy were presented, the analysis of microstructure and mechanical properties after heat treatment was examined by X-ray, SEM, EDS and specialized machines. The results showed that with 3% mass of Sn added into the Cu-Ni-Sn alloy along with heat treatment and deformation, the hardness value reached the range of 221-240HV, the tensile strength and elastic limit reached around 1060MPa and 903MPa respectively. However, after heat treatment and deformation for the Cu-Ni-Sn alloy based on 6% mass of Sn, the hardness value reached the range of 221-318HV, the tensile strength and elastic limit were respectively 222MPa and 263MPa higher than those of the Cu-Ni-Sn alloy with 3% mass of Sn. The result from X-ray analysis showed the deflection of peaks. Nonetheless, the new phases were not observed in SEM and EDS, contrariwise, generated modular structure was considered as the proof of the Spinodal cluster. This fact might be explained by two mechanisms: deformation mechanism and Spinodal decomposition.

The fault detection and diagnosis (FDD) of centrifugal chillers is always a complex difficulty in HVAC systems. This paper develops an online fault detection and diagnosis strategy based on non-linear radial basis function (RBF) to online detect and diagnose the fault of centrifugal chillers. The RBF is adopted to develop the reference feature parameter (FP) models. Exponentially-weighted moving average (EWMA) residual control charts of FP is used to detect the faults. A rule-based diagnostor is developed to online identify the fault. Seven common faults are taken in account for typical centrifugal chillers. The FDD strategy proposed was validated by using the experimental data from the ASHRAE RP-1043 project and the operating data of a centrifugal chiller in an office building of Hong Kong. The test results show that the RBF-EWMA method has achieved significant improvements in accuracy and reliability by comparing with the previous method with SVR-EWMA. The proposed RBF-EWMA method is robust for fault detection and diagnosis in centrifugal chiller systems.

In this paper, theoretical expressions of the mean crushing force of the three different square multi-cell tubes were derived by applying the Simplified Super Folding Element (SSFE) theory. The profiles of three square multi-cell tubes were divided into several basic angle elements: right corner, T-shape, 3-panel, criss-cross, and 4-panel angle element. Numerical simulations and multi-objective crashworthiness optimization were also performed for the three tubes. A Pareto sets were obtained by the linear weighted average method. Deb and Gupta method was utilized to find out knee points from the Pareto frontiers for multi-cell tubes. The simulation results showed that the multi-cell tube type I with right corner, T-shape and criss-cross angle elements was the best one among the three tubes in the aspect of specific energy absorption (SEA). For all the tubes, the stable and progressive folding deformation patterns were developed. Finally, the theoretical predictions well coincided with the numerical results, and also validated the efficiency of the numerical optimization design method.

Multi-cell square tubes under dynamic oblique impact loading were studied in our work. The theoretical predictions of mean crushing force, mean horizontal force, and mean bending moment were proposed by dividing the profile into basic angle elements based on a Simplified Super Folding Element (SSFE) theory. The formulas of an oblique impacting coefficient ( λ ) with a load angle of 15 ° were proposed based on the geometric parameters, the inertia effect and the oblique loading angle by taking the effect of oblique loading and dynamic crushing into account for aluminum alloy tubes. A new method was proposed to find out a “knee point” from Pareto set with maximizing the reflex angle. The optimal configurations of multi-cell tubes were analyzed under axial and more than one oblique impact loadings. The results showed that the FE numerical results agreed well with the theoretical predictions.

Currently, Vietnam ranks second about the coffee export in the world. To match that position, the use of coffee harvesting tools/machines according to the automatic trend is essential. However, the most common forms of coffee harvesting in Vietnam are manual, improved manual-coffee picking machines that are imported from foreign countries. The above harvesting forms have low productivity and have some disadvantages such as labor cost, labor hiring, high labor cost, and long harvesting time, low harvesting, and post-harvesting quality. Studies of scientists around the world have applied the principle of vibration to produce the picking force for coffee fruits, and the picking force is known to be different from many factors in every region of the world growing coffee. The paper presents the method of design and manufacturing an automatic coffee harvesting machine based on the evaluation of picking force for coffee in Vietnam. The influences of eccentric ball mass and vibrating frequency on the magnitude of the picking force are carefully calculated. On that basis, the experimental programming is applied to find the optimal working point of the picking machine for coffee. The results showed that the eccentric ball mass of 8.5 kg, the rotation speed of the eccentric ball from 480 to 574 rpm would produce the picking force by the coffee fruit of Vietnam.

Reliability-based design optimization (RBDO) involves evaluation of probabilistic constraints which can be time-consuming in engineering structural design problems. In this paper, an efficient approach combined sequential optimization with approximate models is suggested for RBDO. The radial basis functions and Latin hypercube sampling are used to construct approximate models of the probabilistic constraints. Then, a sequential optimization with approximate models is carried out by the sequential optimization and reliability assessment method which includes a serial of cycles of deterministic optimization and reliability assessment. Three numerical examples are presented to demonstrate the efficiency of the proposed approach.