Evaluating nanocrystallite size distributions in doped and undoped nanocrystalline ceramics by X-ray diffractometry

Analytical expressions are formulated that enable the lognormal distribution of nanocrystallite sizes and the mean-squared crystal lattice microstrain in both doped and undoped nanocrystalline ceramics to be routinely determined by X-ray diffractometry. Importantly, these expressions, which are also applicable to most well-annealed nanocrystalline metals/alloys, are developed under the consideration that both the experimental and instrumental X-ray diffraction peaks are modeled by split Voigt functions to account for the (hitherto widely ignored) intrinsic peak asymmetry. The general analytical expressions of this new single-peak line-broadening method are then particularized to the case of small nanocrystallites with uniform composition for which a reasonable simplification (i.e., symmetrization of the experimental peak) can be made without compromising the accuracy of the results. Next, as an example of application the method developed is applied to the characterization of a nanocrystalline ceramic powder, and the nanocrystallite sizes so-determined are validated by transmission electron microscopy. The more complete and reliable microstructural information offered by this single-peak line-broadening method could contribute towards the accurate characterization of both doped and undoped nanocrystalline ceramics, and of most well-annealed nanocrystalline metals/alloys as well, a topic of particular research interest today.     

Effect of different compatibilizers on environmentally friendly composites from poly(lactic acid) and diatomaceous earth

Environmentally friendly composites from poly(lactic acid) (PLA) and diatomaceous earth (DE) were successfully manufactured by extrusion, followed by injection moulding. DE was used as a filler; several compatibilizer/coupling agents, namely (3‐glycidyloxypropyl)trimethoxysilane, epoxy styrene acrylic oligomer and maleinized linseed oil, were used to improve polymer–filler interactions. Mechanical characterization was carried out by standard tensile, impact and hardness tests while morphological characterization of the fractured surfaces was conducted by field emission scanning electron microscopy. The effect of DE was evaluated by differential scanning calorimetry and dynamic mechanical thermal behaviour. The results show that the addition of DE provides an improved tensile modulus and induces more brittle composites due to stress concentration phenomena. The addition of compatibilizers in PLA‐DE positively contributes to improve ductile properties, thus leading to high environmental efficiency materials with balanced mechanical properties. Specifically, the compatibility improvement between the PLA and DE was good with maleinized linseed oil and contributed to improving the impact strength, which is a key factor in PLA‐based composites due to the intrinsic brittleness of neat PLA. © 2019 Society of Chemical Industry     

Technology Acceptance Model for the Use of Tablet PCs

Tablet personal computers (tablet PCs) are popular electronic devices worldwide. They influence many aspects of our social lives. Compared with laptop computers, tablet PCs feature characteristics including enhanced portability and display quality. The purposes of this study were to examine users’ attitudes toward tablet personal computers and identify the effects of external factors. This study extended the technology acceptance model and used perceived mobility and viewing experience as the external variables in the proposed model. This study used a web-based survey of 511 participants and found that perceived usefulness and perceived ease of use were key determinants of attitude toward tablet personal computers. Also, the perceived ease of use and usefulness of tablet PCs were significantly enhanced by perceived mobility and viewing experience. In addition, all traditional relationships from the origin technology acceptance model were supported. Lastly, both implications of the study and areas of future research are discussed.     

A variance-constrained proportional—integral feedback controller that tunes itself

Proportional-Integral (PI) feedback controllers have been shown to provide a very robust process adjustment strategy. Recent work by Box and Luceno [1-3] provides PI controller settings that trade-off the variance of the quality characteristic versus the variance of the adjustments, an important concern in manufacturing. A Quality Engineer may desire a particular maximum adjustment variability, perhaps because of safety considerations or because the resolution of the manufacturing equipment. The graphs and tables provided by these authors were developed by minimizing a weighted sum of adjustment and output variance and will not always provide enough information to guarantee a specific maximum adjustment variance. Specifying a constraint on the adjustment variance is much more natural for a Quality Engineer than specifying the value of the relative weight that satisfies the adjustment constraint, and easier than choosing from a list of possible controller designs. In order to obtain a specific adjustment variance, parameter estimates of the process are needed. Moreover, to allow for rapid control after startup and to minimize scrap, it is desirable that on-line estimation occurs during closed-loop operation. This paper presents a PI controller that tunes its parameters on-line during closed-loop operation for a first order process under the assumption that no prior process information is known before starting the control session. Under these conditions, the proposed PI controller provides the minimum output variance for a specified upper bound in the adjustment variance; the value of the Lagrange multiplier associated with the constraint, similar to the relative weight in Box and Luceno's procedure, is computed internally by the controller and there is no need to specify it a-priori. An analysis of the performance of the controller is presented. It is shown that the proposed controller converges rapidly to the desired configuration without sacrificing the performance during the transient phase. g in Operations     

Study of the fabrication of infrared-transparent dielectric aspheric deposits by continuous-wave laser deposition

The fabrication of dielectric aspheric deposits with optical refractive functionality by a continuous-wave laser deposition technique is reported for the particular case of an amorphous As-S alloy. The influence of both the laser power and fabrication times in the deposit thickness profile is studied from the measurements performed by a mechanical profilometer. The use of press-powder tablets as starting material have been found to have a significant effect in the deposition efficiency, and indications of a transition from a discrete to a continuous nature of the target, have also been observed. A notable reproducibility has been found both in the material stoichiometry and thickness profiles. The optical function of the fabricated refractive aspheric deposits has been measured to be similar to one performed by axicon lenses.     

Anodic coloring of titanium and its alloy for jewels production

Anodized titanium with its interference colors, its appearances and its light, is undoubtedly of great appeal to the field of architecture and to all ramifications of design, to visual communication and to the world of fashion. On its surface, it is possible to create a visionary world of colors, perfectly controlled by the imposition of determined anodizing parameters and surface conditions. This article presents one of the applications of anodized titanium, which most earns general interest nowadays in the designers' world, that is, the production of colored titanium jewels. Since titanium is considered a seminoble metal, its use is mainly directed to small series production: therefore, a good know‐how giving high reliability of the anodic coloring process is required. The chosen procedure will be described, together with a full characterization of the obtained interference colors. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012     

A comparative activity study of a new ultra-dispersed catalyst system for a hydrocracking/hydrotreating technology using vacuum residue oil: Merey/Mesa

Ultra-dispersed catalysts give an improvement over the main reactions activity by having a low deactivation rate. They provide as well other advantages like a diminution in the catalysts metal concentration, a reduction in contaminants and also these catalysts can be used in almost every area where heterogeneous catalysts are used. Catalysts synthesis optimization is important to improve process recovery, especially in hydrocracking/hydrotreating processes, where feedstock is vacuum residue. Here, we have evaluated the catalytic performance of two molybdenum–nickel catalysts prepared using different emulsion formulation, named E-T (base catalyst) and AT-48 (new catalyst). Our results showed that, the percentage of converted products for VR 500 °C⁺, asphaltenes and microcarbon are comparable for both E-T and AT-48 catalysts, despite the fact that for the latter a lower molybdenum concentration was used. In addition, post-catalytic particles analyses using SEM and TEM techniques demonstrated that AT-48 catalyst showed a non-aggregated and homogeneous narrower distribution of metallic particles than E-T one. The lower average particle size distribution is related to the improvement of the liquid product yields for the hydroconversion of Mery/Mesa VR using the AT-48 catalyst.     

Effects of tiger nut (Cyperus esculentus) milk liquid co‐products on the quality of pork burgers

Co‐products from the tiger nut milk industry can be given added value if they are used in the manufacturing process of other food products. The aim of this study was to analyse the effect of using tiger nut milk liquid co‐product as a substitute for the water added to pork burger formulations. The results showed that its use in pork burger delayed lipid oxidation and improved cooking properties (less shrinkage), while no significant changes in nutritional value were observed. Pork burgers containing tiger nut liquid co‐product were perceived to be juicier and less fatty than the control, contributing to higher scores for overall liking.     

Investigation of relationships between bulk properties and fraction properties of crude oils by application of the intercriteria analysis

Data from assays of 244 crude oils (condensates, extra light, light, intermediate, and heavy crudes) were processed by the InterCriteria Analysis with the aim to investigate the relationships between bulk properties and fraction properties of the crude oils and the degree of similarity between them. It was found that except the crude bulk properties sulfur, Conradson carbon, and metals content all other studied crude bulk properties exhibited lack of statistically meaningful relations or presence of weak statistically meaningful relations with the crude fraction properties. The use of the InterCriteria Analysis showed that crudes with very similar properties could be identified when a large crude database is available. In this way based on a previous experience in oil refining a selection of potentially beneficial new crudes for processing in a refinery could be made.     

Biomedical sample transportation in the province of Quebec: a case study

Biomedical sample management plays a central role in an efficient health care system and requires important resources. Based on our collaboration with the Quebec’s Ministère de la Santé et des Services sociaux (Ministry of Health and Social Services), this article describes the challenging context of biomedical sample transportation in the Canadian province of Quebec. It is modelled on a variant of the multi-trip vehicle routing problem with time windows where routes need to be planned from a laboratory to satisfy the multiple pick-up requests of each sample collection centre under some practical constraints. We propose and evaluate two alternative mathematical formulations, as well as fast heuristics, to minimise total transportation distances. The performance of the proposed methods is assessed over a large case study based on the network of laboratories in the province of Quebec.