One of the main objectives of technical diagnostics is identification the technical state of the machine. The technical state is described by the values of the object cardinal features. ...Unfortunately, during the operation process, some of the values of these features cannot be measured. It is proposed to estimate the values of the cardinal features based on their initial values and the influence of the forcing factors described by the time histories of the parameters of the operation process. Due to the limited knowledge of the correlation between operational parameters and forcing factors it was modelled in form of fuzzy Mamdani models. In the paper universal automatic method of the models generation was presented. Thanks to it, it was possible to generate the model of the technical state changes in automatic manner. The results of the usage of the generated model in case of real complex technical system can be found at the end of the paper.
With the improvement of living standards, food waste (FW) has become one of the most important organic solid wastes worldwide. Owing to the high moisture content of FW, hydrothermal carbonization ...(HTC) technology that can directly utilize the moisture in FW as the reaction medium, is widely used. Under mild reaction conditions and short treatment cycle, this technology can effectively and stably convert high-moisture FW into environmentally friendly hydrochar fuel. In view of the importance of this topic, this study comprehensively reviews the research progress of HTC of FW for biofuel synthesis, and critically summarizes the process parameters, carbonization mechanism, and clean applications. Physicochemical properties and micromorphological evolution of hydrochar, hydrothermal chemical reactions of each model component, and potential risks of hydrochar as a fuel are highlighted. Furthermore, carbonization mechanism of the HTC treatment process of FW and the granulation mechanism of hydrochar are systematically reviewed. Finally, potential risks and knowledge gaps in the synthesis of hydrochar from FW are presented and new coupling technologies are pointed out, highlighting the challenges and prospects of this study.
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•Review on effects of process parameters on HTC of food waste (FW) is presented.•Hydrothermal reaction of each model component and HTC mechanism of FW are revealed.•Combustion of hydrochar from FW and release of contaminant gases are investigated.•New coupling technologies are proposed in conjunction with hydrothermal processes.•Prospects and challenges for developing hydrochar applications are presented.
In recent times, smart manufacturing systems and materials are being utilized increasingly for producing parts with high strength-to-weight ratios. Consolidation of several assembly parts into a ...single and lightweight component plays a vital role in enhancing the mechanical properties of systems as well as effective energy conservation in several sectors, including aviation, maritime, and automotive industries. Additive Manufacturing (AM) has enabled the manufacturing of lightweight components by depositing materials only when needed and significantly reduce required assemblies. From the different AM technologies, Selective Laser Melting (SLM) is a prominent process used to fabricate near-net-shape and good surface quality parts using metal, ceramic, and polymer materials. The potential of realizing customized complex metallic structures with applications in the biomedical, transportation, and energy industries has piqued the interest of the scientific society in SLM. Although substantial progress has been achieved in comprehending the SLM process and fabricating different materials with this process, however, the industrial application is still restricted. Limitations related to printing of multi-materials, inadequate information on the efficient process parameters for different materials, and porosities on the printed parts are some of the main hurdles buried in this method that prevent it from manufacturing functional parts. Therefore, this review article provides a comprehensive and state-of-the-art study on the SLM process regarding the types of materials used, the printing of reflective material and multi-materials, the effect of several process parameters on thermo-mechanical properties of parts, printing of lattice structure, a novel support structure technique, types of post-processing methods, and basic information on simulation software used for SLM processes. Moreover, the article describes future prospects and suggests research directions for the SLM process.
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•The overall process of the Selective Laser Melting process was briefly summarized.•Printing of reflective and multi-materials techniques and machines are discussed.•The effect of process parameters on the thermo-mechanical properties are identified.•Brief information regarding laser-based simulation softwares are discussed.•Future research openings on the SLM process are highlighted.
•Critical applications require materials with superior surface characteristics.•High energy density and cooling rate make lasers suitable for such application.•Laser cladding and surface alloying may ...develop coating with high bonding strength.•Theoretical and experimental result suggest for better clad and surface properties.•Analysis of clad leads to defect free surface with wide industrial acceptance.
Laser cladding and surface alloying are surface modification techniques employed to fabricate thin coating/layer with improved surface properties or to refurbish surface defects by forming highly resistant gradient coatings/layers on the substrate. High energy density and cooling rates make these techniques suitable to process a wide range of materials. In recent years, due to the development of high power lasers, improved controlling and delivery mechanisms have attracted extensive research in laser surface treatment. Researchers have analyzed various process factors to improve process performance. The experimental and theoretical studies show that the performance of laser cladding and surface alloying techniques can be enhanced significantly by the proper selection of input process parameters. This paper summarizes various research works carried out so far in the area of laser cladding and surface alloying of different materials and their applications. It reports the research outcomes of experimental and theoretical studies conducted to improve the process performance. A brief introduction of various laser surface treatment processes is also included. Besides these various problems, their solutions and trend for future works have also been discussed.
Powder Bed Fusion (PBF) techniques constitute a family of Additive Manufacturing (AM) processes, which are characterised by high design flexibility and no tooling requirement. This makes PBF ...techniques attractive to many modern manufacturing sectors (e.g. aerospace, defence, energy and automotive) where some materials, such as Nickel-based superalloys, cannot be easily processed using conventional subtractive techniques. Nickel-based superalloys are crucial materials in modern engineering and underpin the performance of many advanced mechanical systems. Their physical properties (high mechanical integrity at high temperature) make them difficult to process via traditional techniques. Consequently, manufacture of nickel-based superalloys using PBF platforms has attracted significant attention. To permit a wider application, a deep understanding of their mechanical behaviour and relation to process needs to be achieved. The motivation for this paper is to provide a comprehensive review of the mechanical properties of PBF nickel-based superalloys and how process parameters affect these, and to aid practitioners in identifying the shortcomings and the opportunities in this field. Therefore, this paper aims to review research contributions regarding the microstructure and mechanical properties of nickel-based superalloys, manufactured using the two principle PBF techniques: Laser Powder Bed Fusion (LPBF) and Electron Beam Melting (EBM). The ‘target’ microstructures are introduced alongside the characteristics of those produced by PBF process, followed by an overview of the most used building processes, as well as build quality inspection techniques. A comprehensive evaluation of the mechanical properties, including tensile strength, hardness, shear strength, fatigue resistance, creep resistance and fracture toughness of PBF nickel-based superalloys are analysed. This work concludes with summary tables for data published on these properties serving as a quick reference to scholars. Characteristic process factors influencing functional performance are also discussed and compared throughout for the purpose of identifying research opportunities and directing the research community toward the end goal of achieving part integrity that extends beyond static components only.
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•Review of academic and industrial contributions over the last 25 years.•Practice and evaluation methodologies are explored.•The capabilities of PBF processes and the resulting material properties are linked.•Opportunities for further research are stated to help direct the research community.•A benchmark of mechanical properties obtained to date for PBF are provided.
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Lignocelluloses’ pretreatment is targeted for the improvement of hydrolysis of their carbohydrates, i.e., cellulose and hemicelluloses. Modification of the hardheaded structure of ...lignocelluloses is a fundamental stair in biofuels and biochemicals production. The high crystalline configurations of cellulose embed with hemicelluloses and lignin, give rise to recalcitrance structure. Second-generation biofuel production processes, using lignocellulosic biomass as a feedstock, is based on a three-stage process, including pretreatment, enzymatic hydrolysis, and fermentation. The pretreatment stage is the most critical, influencing, costly stage. The perfect pretreatment process is designated to provide minimum cellulosic crystallinity with remarkable low lignin content as well as inhibitory compounds through a sustainable economical process. In the present review, advances in lignocellulosic pretreatment technologies for biofuels production are reviewed and critically discussed. The article further discusses the pros and cons of the various pretreatment methodologies as well as addresses the role and impact of different process parameters associated with the pretreatment process.
The valorisation of the plant biopolymer lignin is now recognised as essential to enabling the economic viability of the lignocellulosic biorefining industry. In this context, the "lignin-first" ...biorefining approach, in which lignin valorisation is considered in the design phase, has demonstrated the fullest utilisation of lignocellulose. We define lignin-first methods as active stabilisation approaches that solubilise lignin from native lignocellulosic biomass while avoiding condensation reactions that lead to more recalcitrant lignin polymers. This active stabilisation can be accomplished by solvolysis and catalytic conversion of reactive intermediates to stable products or by protection-group chemistry of lignin oligomers or reactive monomers. Across the growing body of literature in this field, there are disparate approaches to report and analyse the results from lignin-first approaches, thus making quantitative comparisons between studies challenging. To that end, we present herein a set of guidelines for analysing critical data from lignin-first approaches, including feedstock analysis and process parameters, with the ambition of uniting the lignin-first research community around a common set of reportable metrics. These guidelines comprise standards and best practices or minimum requirements for feedstock analysis, stressing reporting of the fractionation efficiency, product yields, solvent mass balances, catalyst efficiency, and the requirements for additional reagents such as reducing, oxidising, or capping agents. Our goal is to establish best practices for the research community at large primarily to enable direct comparisons between studies from different laboratories. The use of these guidelines will be helpful for the newcomers to this field and pivotal for further progress in this exciting research area.
With these guidelines, we aim to unite the lignin-first biorefining research field around best practices for performing or reporting feedstock analysis, reactor design, catalyst performance, and product yields.
•Statistical design of experiment approach and the energy density model were correlated for SLM of AlSi10Mg alloy.•The mechanical properties were assessed, including the high temperature creep ...properties.•The energy threshold for processing AlSi10Mg alloy are within the range 60–75J/mm3.
The influence of selective laser melting (SLM) process parameters (laser power, scan speed, scan spacing, and island size using a Concept Laser M2 system) on the porosity development in AlSi10Mg alloy builds has been investigated, using statistical design of experimental approach, correlated with the energy density model. A two-factor interaction model showed that the laser power, scan speed, and the interaction between the scan speed and scan spacing have the major influence on the porosity development in the builds. By driving the statistical method to minimise the porosity fraction, optimum process parameters were obtained. The optimum build parameters were validated, and subsequently used to build rod-shaped samples to assess the room temperature and high temperature (creep) mechanical properties. The samples produced using SLM showed better strength and elongation properties, compared to die cast Al-alloys of similar composition. Creep results showed better rupture life than cast alloy, with a good agreement with the Larson–Miller literature data for this alloy composition.
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