Manufacturing Engineering

Several 65 µm thick epitaxial diamond films prepared on (100) Ib substrates by high power, pulsed microwave plasma assisted chemical vapour deposition (HP-PMPCVD) are studied as a function of surface treatments by cathodoluminescence (CL) and photoluminescence (PL) spectroscopies. They are either as-grown, or polished, or etched by a microwave oxygen plasma, or after applying subsequently the two last processes. In CL spectra, bands due to defects occur at 2.3 eV, 3.07 eV, 3.6 eV and 4.7 eV, the last one being specific of polished surfaces, with nearly no contrast in the luminescence image, contrary to other CL images. A fundamental result consists in demonstrating that the defects induced by polishing can be removed by oxygen plasma etching. Additionally, in order to assess how luminescence spectra originate from a peculiar depth or not, a bevelled sample is studied. PL spectra are acquired on the sample side while CL spectra are measured at several points on the bevel top side till to the Ib substrate. Comparison of the two sets of result show that the H3 signal originates from the Ib substrate even if it is present in the CL spectra of the film. An analysis of the change in the intensity of the TO free exciton line, defect bands and H3 signal, along decreasing photon energies, as a function of the thickness of the remaining HP-PMPCVD film, is performed with the help of a model taking the diffusion of the unrecombined excitonic pairs and the re-excited photoluminescence into account. CL images recorded at specific wavelengths, which do not show inverted contrast, are also assessed. From these data, the exciton diffusion length is evaluated to 11 µm in the major part of the epitaxial layer except for the first 20 µm close to the Ib substrate where it decreases down to 2 µm. This study sheds light on the interpretation of luminescence spectra excited by an electron beam in undoped diamond layers. Defects bands due to damages induced by polishing and etching processes are also documented.

Schottky contacts on the (1 0 0) surface of homoepitaxial boron-doped diamond films are investigated. The potential barrier height of a metallic interface build in a ultra-high vacuum (UHV) chamber by the deposition of one monolayer of titanium, subsequently covered with a thick film of silver, is studied. From X-ray photoelectron spectroscopy spectra, a barrier height of 1.7 eV is derived. However, after annealing in air, the current-voltage characteristics analysed at several temperatures allow the plot of a Richardson's diagram, which yields a 3.4 eV barrier height, higher than half the diamond bandgap. Annealing of the Ti layer at 400 8C in UHV induces carbide formation, which ensures a good adhesion of the metallic coating. Comparison of the series resistance of diodes implemented either only on a moderately doped diamond layer (a few 10 cm ) or on pyp double 17 y3 q layer is done. In the former case, the 0.38 eV activation energy for boron acceptors ionisation is clearly identified while it decreases to 0.06 eV in the latter case, with an absolute value of the series resistance typically five orders of magnitude lower at ambient temperature. Consequences and applications of these findings are presented.

The electrical properties of Schottky contacts on the (100) surface of Boron doped diamond films epitaxially grown on Ib substrates are investigated in this work. The role of Boron doping concentration and extended defects detected by cathodoluminescence is correlated to current voltage characteristics, rectifying efficiency and high voltage performance of the diodes up to 1 kV and more. The influence of surface treatment prior to metal deposition is highlighted and the choice of metal for the Schottky contact is discussed. The paramount importance of using an oxidised diamond surface at the Schottky contacts and outside is demonstrated. Decreasing the series resistance of diodes is obtained with a stack of two layers, the upper one being lightly doped while the deeper one contains Boron concentrations close to the metallic conductivity threshold (4 × 10 20 B/cm 3 ). Several architectures are studied. The ohmic contact directly laid on the heavily doped layer permits forward current densities of 66 A/cm 2 under 4 V at room temperature and switching times in the nanosecond range. This set of results shows that p-type diamond is an adequate semiconductor for implementing high speed, high power and high voltage electronic rectifiers.

Despite their steady improvement over the last decades, the present UV detectors exhibit some limitations inherent to their silicon technology. Yet, the utmost spatial resolution, temporal cadence, sensitivity, and photometric accuracy will be decisive for the forthcoming space solar missions. The advent of novel diamond or nitride imagers would surmount many current weaknesses, thus opening up new prospects and making the instruments cheaper. As for projects like the Solar Probe of NASA, or the Solar Orbiter of ESA, the aspiration for diamond UV detectors is still more sensible for these spacecrafts will approach very near to the Sun where the heat and the radiation fluxes are tremendously high. This triggered the initiative of an original R&T programme entitled BOLD described in this paper. We depict motivations and intentions, and report on dedicated experiments with several devices under EUV synchrotron light, NUV laser, and micro-Raman spectroscopy.

Simultaneous etching of NID, lightly boron-doped, phosphorus-doped homoepitaxial CVD films and Ib HPHT crystal was achieved at RT in a home-made reactor producing O ECR plasma which was homogeneous on approximately 200 cm . Etching y2 2 rates varying from 60 (at y30 V) to 40 or 120 nmymin (at y140 V) are obtained with n-or p-type-doped samples, respectively. These etching rates are higher than those with O RF plasma, and those with previous inhomogeneous O ECR plasma with 2 2 samples at 100 8C.

Defects involving hole traps in diamond are investigated with Fourier Transform Deep Level Transient and Isothermal Spectroscopies in several Boron doped diamond films epitaxially grown on Ib substrates in our own reactor, either with or without oxygen in the gas mixture. It is shown that both pre-and post-treatments can stabilize a continuous distribution of traps which was not necessarily present initially. The ionization energy and capture cross section of each trap is determined and compared to previous experimental and theoretical data. From deep trap profiling, it is shown that concentrations are all decreasing below 10 15 cm -3 beyond about 250 nm below the interface with the Schottky metal. All these traps do not exist in epilayers prepared with oxygen in the gas mixture. This set of properties strongly suggests that hydrogen is involved in traps, probably associated with either structural defects or Boron.

The article presents the combined use of three design methodologies applied to design of a textile product. Article methodologies: axiomatic design, the morphologic features and FAST diagram are used to design a technological fabric treated for issuing infrared radiation.

This study was conducted a small textile industry and aims to assess and investigate the practices used in the implementation of quality management systems and tools to ensure process improvement. The purpose, therefore, is to implement the quality system and also analyze the management practices and tools used to ensure quality, comparing practices and showing the results in productivity and product quality. The research was conducted through a case study, we intend to analyze the reality of the organization in making the visit on-site observation. A case study can thus elucidate a number of issues on the development of quality in the textile industry of small, checking possible kinds of inefficiency or improvement points unexplored. To verify that the controls of the company to support the implementation of quality management system were conducted evaluation, analysis, testing and monitoring in all sectors.

Modeling as a technique for preparing the deployment of a system of quality management in a small business in the textile sector, the methodology of BPM was used as support for implementation of quality management system. The BPM was used to identify the actions needed to improve the system and the communication of those involved. Trying to comprehend, perceive and understand the existing operations in the process of knitting textile production. The study shows the documentation, verification and analysis of the process of knitting. The technique allowed the collection of sufficient data to analyze the critical points for the preparation of the implementation of quality management system. The results presented in the mapping of business processes have made possible the flow analysis, the sequence of activities, documentation and implementation of quality indicators.

Within the framework of recycling and reusing carbon fibre, this study focused on the fabrication of a thermoelectric composite encompassing recycled carbon fibre and two thermoelectric fillers (i) bismuth telluride and (ii) bismuth sulphide. This study investigated the effect of the concentration of bismuth telluride and bismuth sulphide fillers respectively on the thermoelectric, morphology, structural and thermal stability of the recycled carbon fibre thermoelectric composites. The optimum thermoelectric filler concentration is 45 wt% for both fillers, which resulted in a power factor of 0.194 ± 9.70×10 -3 µWK -2 m -1 and 0.0941 ± 4.71×10 -3 µWK -2 m -1 for recycled carbon fibre-bismuth telluride and recycled carbon fibrebismuth sulphide composites respectively. This study exhibited the energy harvesting M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT capabilities of recycled carbon fibre composites from low grade waste heat when coated with thermoelectric materials.

Gap-active electrical discharge machining (GA-EDM) is a novel approach which provides a gap-sensible and auto-adjustable electrode-retraction system. This mechanism is conceptualized from the principle of 'parallelplate capacitor having two dielectric mediums' where the inter-electrode surfaces are acted as the parallel plates. The kerosene is used as a fundamental dielectric substance, and a relatively denser and viscous layer of bio-oil is treated as secondary dielectric material. Besides this, a servo-controlled tool arrangement is employed, which is auto-sensible and synchronized with the flushing system. This multi-dielectric enhances the equivalent capacitance of the plasma-column and can dissipate huge energy during the discharging phase. The extensive heat melts most of the solidification defects and reforms the entire texture, which is far better than the surface developed with normal EDM. Moreover, the viscous layer of the secondary fluid (above the workpiece) provides an adhesive grip and slow heat dissipation procedure, which can check the formation of micro-cracks, develop due to residual effect of rapid quenching. Besides these, the flushing sensible electrode retraction system ensures an adequate passage for flushing, which helps in proper debris-expelling and controlled heat dissipations. Therefore, the adopted gap-active (GA) mechanism can facilitate better textual features with negligible indentation, solidified-agglomerates, and cracks. It is observed that the secondary dielectric enriches the carbon containments in the texture and forms a 10-14 % harder surface than the normal-EDM.

Laser marking is an elegant, clean, fast and non-contact permanent marking method with high durability. The present paper deals with the analysis of laser marking process parameters like lamp current, laser scanning speed, pulse frequency, average and peak power of laser beam using Nd: YAG laser on various laser marking characteristics like the mark width, mark depth and mark contrast are studied during pulsed Nd: YAG laser marking on zirconia ceramic material. Analysis based on optical photographs has also been performed. The present study shows that high pulse frequency and lamp current with low scanning speed has more effect to achieve the minimum mark width, maximum mark depth and mark contrast. In addition to it, a multi objective optimisation has also been performed.

Electrochemical Discharge Machining (ECDM) process has great potential to machine electrically non-conducting engineering ceramics and can be applied for micro-machining operation. This research paper includes the experimental investigation to study the range of the parametric setting for micro-machining operation as well as the effect of various process parameters such as applied voltage, electrolyte concentration and inter-electrode gap on Material Removal Rate (MRR), Radial Over-Cut (ROC) and Heat Affected Zone (HAZ) thickness during micro-drilling of non-conducting engineering ceramic materials such as Aluminium Oxide and Zirconium Oxide. The experiments have been performed using electrolyte of KOH and NaOH salt solution. In this paper, an experimental investigation has been made to find out the optimum value of ECDM process parametric conditions for higher MRR, lower overcut and also lower HAZ thickness during micro-drilling on ceramics. The quality of the hole during micro-drilling greatly depends on the applied voltage and electrolyte concentration.

The advent of technological development and integration of many fields including digital, physical and biological systems are key to the success of the Fourth Industrial Revolution, (FIR). Embracing of industry 4.0 by organizations is the key to global competitiveness and on the contrary, failure to adopt FIR may cause countries to lag behind in terms of economic development. The current studies have not fully covered on the use as well as levels of industry 4.0 implementation within developing countries. Most developed countries have put in place public policies that focus on implementing industry 4.0 in their respective countries. This means that it becomes critical, if not imperative, that developing countries like Zimbabwe also take steps to adapt industry 4.0 so as to remain relevant and competitive in the global economy as well as not be adversely affected by these technologies if not adopted. Zimbabwe, like most developing countries encounters a lot of problems in its endeavor to fully implement FIR technologies such as lack of commitment, infrastructure and lack of skilled workers. The objective of this study is to assess the implementation levels of industry 4.0 in Zimbabwean Manufacturing Industries, identify and discuss the challenges as well as issues faced by the organizations as well as coming up with recommendations in the implementation of industry 4.0 framework.

Efficient and versatile charging solutions are essential for modern applications requiring portable energy systems. This paper presents a novel portable charger powered by an isolated split-core current clamp, enabling direct charging from power lines. The system utilizes inductive coupling to draw AC current from these lines, which is then regulated to a precise voltage for battery replenishment. The proposed design features an interleaved resonant topology with a semi-active rectifier, achieving high efficiency and adaptability to a wide range of input voltages. This architecture supports a variable DC bus voltage, enabling the resonant converter to operate optimally near its resonant frequency for maximum performance. To ensure a lightweight and efficient design, the converter eliminates traditional transformers, incorporating a capacitive element within the resonant network for galvanic isolation. A cascaded dual-control strategy in the interleaved structure ensures precise voltage regulation. Designed to be compatible with 1-6 cell Li-Ion batteries, the charger offers extensive versatility. Experimental results from a 2.5-200 W prototype, with an output voltage range of 4.2-25.2 V, demonstrate a peak efficiency of 94%, validating the effectiveness of the proposed charger for gridconnected applications.

A sound, mechanics-based approach has been developed to allow conventional creep data to be obtained from impression creep test data; the reference stress method was used, to analyse the results of axisymmetric finite calculations, for this purpose. The equivalent uniaxial stress was found to be 0.296 times the mean indenter pressure and the effective gauge length was found to be about 0.755 times the indenter diameter. These values correspond closely with those which have been obtained by fitting indenter creep data to conventional uniaxial creep data.

The demand for a focus on nature-oriented design education and the improvement of 21st century teaching skills has grown exponentially in recent years. Biomimicry addresses these needs but the lack of scientific research on didactic methodologies leaves teachers and students utilizing examples with little knowledge on how to start efficiently within the design process. This research structurally assesses how biomimicry is currently taught and learned, which difficulties arise and which applications are most useful, so that effective educational strategies are developed, evaluated and implemented. This ultimately increases the number of successful sustainable, circular designs produced by multi-disciplinary student teams.

Urbanization is the most important aspect of societal advancement, particularly in densely populated capitals like the city of Dhaka in Bangladesh. There have been numerous mega projects incorporated within the city, but there is still a lack of proper planning mechanisms for further expansion. As the city continues to evolve, efficient planning becomes imperative to sustain growth and enhance living standards. With the help of Voronoi diagrams, this research offers a systemic approach to expanding Dhaka's urban landscape, which, to our knowledge, is a unique approach to solving the problem of representing Dhaka city. Through a fusion of Voronoi tessellation and Delaunay triangulation, the key map zones of the city are mapped, identifying optimal expansion sites and the shortest destination points for future infrastructure project routes. By addressing Sustainable Development Goal 11 (Sustainable Cities and Communities), the methodology aims to foster sustainable urban growth, enhance livelihoods, and mitigate congestion. Through empirical analysis and spatial modeling, the findings in the research provide actionable insights for policymakers, urban planners, and stakeholders, facilitating informed decision-making for Dhaka's sustainable development trajectory.

Adsorption processes of 1,4-phenylene diisothiocyanate (PDITC) on two new platforms of the type graphene oxide (GO) sheets and GO layers functionalization with polydiphenylamine (PDPA) are studied by Raman scattering and photoluminescence (PL). An interaction in solid state phase of the two constituents, i.e. PDITC and GO sheets, and a deposition of PDITC onto the PDPA functionalized GO layers, respectively, by the drop casting method, were performed. In the first case, it is shown that interaction in solid state phase of GO with PDITC leads to an intercalation of the organic compound between GO sheets simultaneously with the appearance of the o-thiocarbamate groups, that induces: (i) an enhancement of the PDITC Raman lines situated in the 400-800 and 1000-1300 cm -1 spectral ranges, (ii) a change in the ratio between the relative intensities of the two Raman lines peaked at 1585 and 1602 cm -1 accompanied by an up-shift in the case of the second line and (iii) a down-shift of the PDTIC PL band from 502 to 491 nm. Using cyclic voltammetry, an electrochemical functionalization of the GO layers with PDPA doped with H 3 pMo 12 o 40 heteropolyanions takes place, as demonstrated by Raman scattering and FTIR spectroscopy. The presence of the amine groups in the molecular structure of the doped PDPA functionalized GO layers induces a chemical adsorption of PDITC on this platform, when the thiourea groups appear simultaneously with o-thiocarbamate groups. A chemical mechanism is proposed to take place at the interface of the GO sheets and the doped PDPA functionalized GO layers, respectively, with PDITC.

Environment-related issues have become a global concern due to which firms are considering sustainability. A key to achieving long-term development is understanding these issues. This research seeks to illuminate the effects of green supply chain management practices on firms' environmental performance and the impact that the relationship of the two has on competitive advantage. However, the study draws on the Resource-Based View (RBV) and Natural-Resource-Based View (NBV) theories to understand the interplay between the factors affecting the scope for improvement of internal environmental management practices. For this study data was collected from 200 respondents through the convenience sampling method and quantitatively analyzed. The results imply that green supply chain management strategies should be adopted to promote internal environmental management. Firms implement effective GSCM practices to improve environmental performance to develop a competitive advantage in the marketplace. This study adds to understanding how such green practices can be integrated into an organization's core operation and emphasizes the importance of green practices in enhancing organizational growth as well as environmental sustainability. These practices enable firms to face environmental challenges in terms that will lead to long-term success and contribute to sustainable development.

In this research, with the installation of Sigfox's antenna in our university, we installed IoT equipment that makes use of the Sigfox network. As an example of an IoT device, we tried installing it on a water meter to acquire data, such as water usage fee, via internet. Also, using the system outline, we constructed it as an educational system.

CNTs) are known to be excellent electron field emitters. However, the fundamental factors that contribute to the emission stability have not been well studied. Here, we found that stability of emission current from CNTs is related to their graphitic orders. We have tested various types of CNTs grown by thermal chemical vapor deposition (CVD) and plasma enhanced CVD (PECVD). Our samples were grown in a circular area of 0.385cm 2 on low resistance Si substrates. Field emission measurements were conducted in a planar diode configuration, with a pair of electrodes separated with a gap of 1000 ± 10 µm. The vacuum level during the measurement is ∼2.0 X 10 -7 mbar. We found that the emission currents from PECVD grown CNTs degraded by as much as 70% within a period of 20 hours. In contrast, random CNTs grown by thermal CVD exhibit stable emission current for at least 20 hours. These CNTs also have relatively lower threshold electric field of field emission. Since all samples are tested in a same condition, the detected results are thus related to the structural order of the CNTs. Transmission electron microscopy and Raman spectroscopy confirmed that field emission stability is depends on the graphitic structures of these CNTs.

The dual motor drives fed by a single inverter are purposely designed to reduce size and cost with respect to single motor drives fed by a single inverter. This paper presents the speed responses behavior of Dual Permanent Magnet Synchronous Motor (PMSM) driven by Mean and Differential Torque Control technique. The drive is simulated by using Hysteresis Current Controller. MATLAB/Simulink is chosen as the simulation tools. The performance of speed, current and torque responses for Dual Motor PMSM fed by a single inverter is presented. The applied technique shows satisfactory speed regulation for a wide range of speed either with load, no load or variation of load.

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The three­dimensional weld pool top surface shape provides important informa­ tion about the state of weld penetration during welding. In this study, a method was developed to quantitatively relate weld pool surface height to the reversed electrode image (REI) on the weld pool surface. This new feature was extracted from the weld pool image using a passive vision­based monitoring system during gas tungsten arc welding (GTAW). Due to the specular reflection of the weld pool top surface, the REI is visible on the weld pool surface during GTAW. The position of the REI was determined with a robust image processing algorithm. Based on the principle of light reflection, the distance between the electrode tip and the REI (DERI) was related to the weld pool surface height. By assuming the weld pool surface was a spherical mir­ ror, a reflection model was established to calculate the surface height (SH) index based on the measurement of the DERI, arc length, and weld pool geometry. The pro­ ...

The properties of high-quality soap is determined by its cleansing, foam formation, surface tension, emulsion capacity, pH, etc. To produce a generally better product, soap manufacturing companies take these properties into account during production which necessitated the physical assessment properties of some selected made-in-Nigeria synthetic surfactant for surface activity. The samples were evaluated based on tests for saponins, foam formation and stability, emulsion formation/capacity, surface tension, and pH at different concentrations. The percentage of each of the synthetic surfactants (Ariel=DA, Bonus=DB, Good mama=DG, Sunlight=DS and Zip=DZ) concerning foam formation at five minutes and stability after 30 minutes were as follows; DZ(6.7) > DS(6.3) > DG(5.3) > DA(4.2) > DB(4.1) and DZ(2.6) > DG(1.9) > DA(1.1)/DS(1.1) > DB(1.0) in cm, respectively. The study of the emulsion formation/capacity of the different samples at different concentrations in terms of creamy behaviour was observed as DS > DZ > DA > DG > DB. All the samples studied showed a good reduction in surface tension. At 2g and 10g of the different samples, the following results were obtained: DS(2.87), DZ(20.25), DB(21.55), DA(21.65), DG(21.85) Nm-1 and DS(22.45), DZ(22.25), DB(22.45), DA(26.65), DG(22.65) N/m, respectively. The result of the pH values of the different samples varied within the range of 10.80 to 10.91 as moderately weak base with an increase in concentration. Detergents studied conform to the minimum quality examinations but regular assessment check should be carried out by enforcement/regulatory agencies to ensure quality of detergents produced in the country meets the minimum required standard.

The predominant part of the innovations is the implementation of the achievements of modern information technologies in business organizations. The main problem for investors is that they cannot determine the exact moment to do so, because the industry is directly related to the technological revolution in microelectronics. New IT products are constantly coming to market, and the price of existing ones is collapsing under Moore’s Law. This article answers the question, when to invest in new technology, if the price of the investment is reducing about 2 times for a period of a year and a half.

The manufacturing chain is usually made of several processes, to create the final surface with regard to design specifications. Manufacturing processes are composed by a complex database, which contains the operating parameters and their settings combinations that impact on the surface parameters. This database may be composed by measured values and it is important to determine the non-measured values through modelling methods to master the final result. This paper aims at establishing a protocol to determine the laser polishing operating parameters for milled and additive lasermanufactured primary surfaces. Several experiments enable to propose models coming from polynomial regression calculus. The proposed models are 88-99% correlated with experiments and the laser polishing parameter enables to bring the initial surface roughness down to 99%. Finally, experiments and models are integrated into a global database to select the laser polishing process parameters regarding both initial milled and additive laser-manufactured surfaces.

Additive manufacturing is an innovative way to produce complex parts. Nowadays, knowledge about mechanical properties and production costs are well known. Many studies found in the literature present comparisons between different additive manufacturing technologies based on technical or economical criterions. However, the environmental analysis of the phenomena that occur during the manufacturing step is still limited. To ensure the development of these processes it seems important to get predictive models of the environmental impacts, allowing to evaluate the product from a technical, economic and environmental point of view. This paper presents a new methodology for the environmental impact evaluation, combined with a technical and economical assessment. This methodology is applied on multiple additive manufacturing processes and will help manufacturers like a decision-making tool to make a choice of manufacturing process based on multiple criterion.

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Additive manufacturing (AM) is a high-valued production application for the manufacture of functional parts. Despite significant advances in the AM field, numerous challenges remain regarding the integration of AM processes into a complete, generic, and adaptive digital thread based on standards. These challenges hinder the adoption of AM in traditional manufacturing companies. In this context, this study proposes a methodology for the development of a new AM digital chain model, named the Hierarchical Object-Oriented Model (HOOM). The HOOM is based entirely on object-oriented modeling that uses a collection of objects containing stored values of the instance variables found within an object. It comprises seven levels from the product design stage to postproduction and validation stages. In order to assess the HOOM, it was implemented and tested through the manufacture of two test parts in a complete high-level digital chain based on the Standard for the Exchange of Product model data compliant Numerical Control. Results from the application of the HOOM unique data structure demonstrated enhanced transparency, standardization, interoperability, scalability, and modularity of AM project data. Moreover, the HOOM was shown to enable bi-directional data flow and to support cloud manufacturing.

Substantial progress and development in additive manufacturing (AM) technologies have been realised during the last decade but have hardly been implemented on AM systems due to old numerical solutions still used by the AM digital thread, for instance STL (1987) and G-code (ISO 6963, 1982). In this field, more traditional processes like machining have challenged this issue by adopting the Standard for the Exchange of Product model data compliant Numerical Control (STEP-NC) standard that enables advanced and intelligent manufacturing by taking advantage of the full computing performance of numerical controllers in manufacturing machines. This standard integrates the whole digital chain (CAD-CAM-CAPP-CNC-CMM) in a unique file with information on design and manufacturing and enables manufacturing of high-value products directly without numerical data conversion or post-processing. This study presents a new STEP-NC data model for AM technologies developed with the ISO TC184/SC1/WG7 committee. A STEP-NC platform initially developed for machining processes has been adapted to implement and validate the AM data model. It enables AM directly from a STEP-NC file, as well as hybrid manufacturing (AM and machining), and allows integration of several optimisation and simulation modules that extend the possibility of advanced and intelligent AM, for instance inprocess manufacturing optimisation.

The additive laser manufacturing (ALM) technique is an additive manufacturing process which enables the rapid manufacturing of complex metallic parts and the creation of thin parts so as, for example, to decrease parts weight for biomechanical or aeronautic applications. Furthermore, compared with selective laser sintering technology, the ALM process allows creating more huge parts and material gradient. However, for aesthetic or tribological functions, the ALM surfaces need an additional finishing operation, such as the polishing operation. Polishing processes are usually based on abrasive or chemical techniques. These conventional processes are composed by many drawbacks such as accessibility of complex shape, environmental impact, high time consumption and cost, and health risks for operators. In order to solve these problems and to improve surface quality, the laser polishing (LP) process is investigated. Based on melting material by laser, laser polishing process enables the sm...

Nowadays, due to rapid prototyping processes improvements, a functional metal part can be built directly by Additive Manufacturing. It is now accepted that these new processes can increase productivity while enabling a mass and cost reduction and an increase of the parts functionality. However, the physical phenomena that occur during these processes have a strong impact on the quality of the produced parts. Especially, because the man-

Rapid manufacturing techniques are typically either material addition or material subtraction processes. Direct metal laser sintering (DMLS) is a material addition process that enables the rapid creation of complex parts via laser sintering (or electron beam melting) whereby layers of powder are deposited and then partially or totally melted using a laser. This technique is directly challenging other more rapid, but subtractive manufacturing processes like high-speed milling (HSM) and electro-erosion. In terms of machining, the capacity of rapid tooling to quickly manufacture complex shapes, like conformal cooling channels, is an advantage (Boillat in

The droplet formation during melting of a 400 mm diameter electrode is simulated with a 3D multiphase-MHD approach. The computational model includes a layer of slag and a layer of liquid steel. A VOF approach is used for the interface tracking and a potential formulation is used for the electric and the magnetic field. The Lorentz force and the Joule heating are recalculated at each time step in function of the phase distribution. The first results provided by this model are presented.

The green synthesis of metallic nanoparticles (NPs) has attracted tremendous attention in recent years because these protocols are low cost and more environmentally friendly than standard methods of synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver NPs using an aqueous solution of Pulicaria glutinosa plant extract as a bioreductant. The as-prepared silver NPs were characterized using ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. Moreover, the effects of the concentration of the reductant (plant extract) and precursor solution (silver nitrate), the temperature on the morphology, and the kinetics of reaction were investigated. The results indicate that the size of the silver NPs varied as the plant extract concentration increased. The as-synthesized silver NPs were phase pure and well crystalline with a face-centered cubic structure. Further, Fourier-transform infrared spectroscopy analysis confirmed that the plant extract not only acted as a bioreductant but also functionalized the NPs' surfaces to act as a capping ligand to stabilize them in the solvent. The developed eco-friendly method for the synthesis of NPs could prove a better substitute for the physical and chemical methods currently used to prepare metallic NPs commonly used in cosmetics, foods, and medicines.

This work investigates how the input parameters (pulse current, polarity, pulse on time, and duty time) in EDM of machining titanium alloy Ti-6Al-4V with graphite electrodes effect on surface integrity and material removal rate. The approach employed involves the design of experiments (DOE) method. The results showed that better surface finish is achieved by using positive polarity on the electrode, however this condition leads to lower material removal rate. The white layer thickness is mainly influenced by the pulse on time and it increases as the pulse on time increases.

In recent years, agro-industrial residues are focusing attention worldwide as a new source of pozzolans; in Brazil one of the wastes generated from agro-industrial activities comes from elephant grass that is cultivated as biomass for energy cogeneration. The goal of this paper is to analyze the influence of elephant grass, once activated at 700 C for 1 h in electric furnace, on the evolution of the hydration reaction as well as physical and mechanical properties in blended cement elaborated with 20% of elephant grass ash. For the present study, different instrumental techniques of characterization and methodologies (XRF, XRD, TG/DTG, mercury porosimetry, isothermal calorimetry and mechanical strength) were used. The results obtained in the present work show, that due to its high pozzolanic activity, the elephant grass ash activated at 700 C can be used as an alternative pozzolan in the blended cement manufacture. Additions of 20% of ash confirm the formation of CSH gels and hexagonal C 4 AH 13 as main products from hydration as well as pozzolanic reaction. The 20% ash blended cement showed lower heat evolution than OPC and similar to the 20% silica fume blended cement, a 12% of reduction of compressive strength and an important reduction of pore sizes below 50 nm.

The research has carried out to introduce Six-Sigma philosophy in Bangladesh, especially in Manufacturing Industry. To show the technical pathway of implementing this technique in our industries for improving the productivity and quality was the main concern of this paper. Present Sigma Level is calculated as a part of the framework and total factors, which are directly related with the process, are taken under calculation. At the same time all the process related to production are clearly observe. As a whole, the total improvements of production system by implementing the Six-Sigma tools were our research goal. A Fan Manufacturing Company was our research area where it has possible to analyzed and implemented. In the thorough procedure, DMAIC is used as technical tools for developing the process. Finally, by changing the traditional layout to balanced layout model as per DMAIC approach, remarkable improvements have been achieved.

The research has carried out to introduce Six-Sigma philosophy in Bangladesh, especially in Manufacturing Industry. To show the technical pathway of implementing this technique in our industries for improving the productivity and quality was the main concern of this paper. Present Sigma Level is calculated as a part of the framework and total factors, which are directly related with the process, are taken under calculation. At the same time all the process related to production are clearly observe. As a whole, the total improvements of production system by implementing the Six-Sigma tools were our research goal. A Fan Manufacturing Company was our research area where it has possible to analyzed and implemented. In the thorough procedure, DMAIC is used as technical tools for developing the process. Finally, by changing the traditional layout to balanced layout model as per DMAIC approach, remarkable improvements have been achieved

Reverse Logistics (RL) activities are practiced by most Brazilian industries, including the automotive one. However, a relevant problem is to identify how different RL programs can affect corporate performance indicators. Analytic Hierarchy Process (AHP) is one of the analytical tools, which can be used to handle a multi-criteria decision-making problem and the Analytic Network Process (ANP) is a similar technique, but can capture the interdependencies between the criteria under consideration. Both approaches were adopted here to study the influence of RL practices in automotive corporate performance. Preliminary results indicated that both methods can be used, being AHP the most efficient, because it requires a smaller number of judgment, and ANP the most reliable, because it considers element dependencies, which is more compatible to the reality of the Brazilian automotive sector.

One of the most conventional approaches of quality control in metal weldments is the evaluation of residual stresses and distortion. Constraining the structure during welding, is the significant key parameter for optimizing the residual stress. In this research, an attempt was made to obtain the best welding constraint of 5XXX Al alloy lap joints during double pass GTAW. A 3-Dimentional finite element simulation was utilized for determining the effect of three different types of local U-shape Fixture (LUF) on residual stresses distributions and distortion. Considering sequentially coupled thermal-mechanical strategy, double ellipsoidal modelling of heat source and element death and birth technique were used in simulation. Thermocouple and LVDT’s set up were applied to validate thermal and mechanical results, respectively. Results provided by simulation show acceptable agreement with experimental values. According to results obtained from simulation, suitable LUFs selected based on o...

The ultrashort pulse laser in material processing of micro/nanoscale has emerged as a useful application due to its capability of high precision control on heating and heat affected zone. The non-Fourier effect in heat conduction becomes more predominant as the duration of heating becomes extremely small which is the case of ultrashort pulse laser. To analyze the heat transfer process by an ultrashort pulse laser, a three dimensional finite element based numerical model is developed assuming finite speed of thermal wave propagation with two phase lags. The present work also describes the finite element formulation using phase lag boundary conditions. The numerical model is developed indigenously using an Intel FORTRAN compiler. The transient heating and cooling phenomena are analyzed for the effect of two relaxation times, variation of pulse width, and multiple pulses. The model results are validated with ultrashort pulse laser heating of a thin gold film. The accuracy of the computed results shows promising application of the developed numerical model for differential influence of process parameters in micro/nano scale heat transport by ultrashort pulse laser processing. V

The biomass supply chain constitutes a system that is highly dynamic and stochastic. The developed and proposed systems architectures for the management of the supply chains of typical industrial products do not directly apply to the case of the biomass supply chain. Nevertheless, it is imperative that a dedicated framework is needed according to the industrial standards. In this paper, a framework for the biomass Supply Chain Event Management (SCEM) supporting the efficient management of inter-organizational events within the examined supply chain is proposed and analyzed. The conceptual model includes the identification and specification of events and the preparation of necessary notification based on information needs.