3D topology optimization for cost and time minimization in additive manufacturing

Structural and Multidisciplinary Optimization - As the frontier of modern-day engineering challenges pushes forward, the integration of multiple strategies to reduce manufacturing cost and increase...     

Application of hand-held mobility spectrometers as sensors in manufacturing industries

Ion mobility spectrometers (IMS) are small, lightweight, extremely robust devices with low power requirements, no moving parts, no absolute requirement for gases or vacuums, that can be operated at ambient temperatures and pressures, and yet are capable of measuring vapour phase concentrations of organic chemicals at very low levels (sub-μg/l). IMS are capable of analysing complex mixtures and producing a simple spectral output. Volatile components produce measurable negative and positive product ions in the spectrometer through chemical ionization. The spectra produced are essentially the vapour phase fingerprints of the target molecules/mixture. Quantitative data can be obtained provided instrument response is within the linear dynamic range of these instruments, but most practical applications of IMS have used the technology in a qualitative manner in situations which require just an above/below threshold or positive/ negative response.In the manufacturing industry there are many examples where the aroma/odour of raw materials has safety or product quality implications. IMS was not developed to replace traditional methods of analysis, e.g. GC/MS or sensory panels, but rather to provide a rapid, qualitative response complementary to more established methods. This paper reports on the use of a hand-held ion mobility spectrometer to characterize the vapours produced by volatile organic compounds,fresh herbs and retail spice mixtures at ambient temperature and pressure. The results show that by monitoring in both ion acquisition modes, ion mobility spectrometers are capable of discriminating between a wide range of products.     

Effect of ammonium chloride on leaching behavior of alkaline anion and sodium ion in bauxite residue

This study focused on leaching behavior of alkaline anion and sodium in bauxite residue through ammonium chloride treatment. The results showed that the pH of bauxite residue decreased from 10.49 to 8.93, total alkaline anion ( ${\text{HCO}}_3^{?},{\text{CO}}_3^{2?}$, OH^?, $\text{A}1{\text{O}}_2^{?}$) concentration reduced from 38.89 to 25.50 mmol/L, leaching rate of soluble sodium was 80.86% with ammonium chloride addition of 0.75%, liquid/solid (L/S) ratio of 3 (mL/g), temperature of 30 °C and reaction time of 18 h; L/S ratio was the main factor affecting the removal of alkaline anion and the leaching of sodium. Furthermore, ammonium chloride promoted the dissolution of diaspore and changed the micro/morphological characteristics with the increase of massive structure. The findings of this work will contribute to achieve soil-formation of bauxite residue.     

Theoretical fitting characteristics of typical soft contact lens designs

Purose

To calculate theoretical fitting success rates (SR) for a range of typical soft contact lens (SCL) designs using a mathematical model.

The hybrid-adjoint method: a semi-analytic gradient evaluation technique applied to composite cure cycle optimization

A method is presented for determining the optimal autoclave temperature history for pre-impregnated thermoset composites based on their failure performance. A coupled finite-element model that incorporates a thermochemical and incremental elastic analysis is used to predict the residual stress distribution at the edge of a thick composite beam. The optimal autoclave temperature is sought using a gradient-based optimization algorithm. The objective is designed to maximize the minimum failure load of the manufactured beam amongst a set of load cases, while the constraints are imposed to ensure that the composite is uniformly cured and does not sustain temperature damage during the manufacturing process. The hybrid-adjoint, a novel semi-analytic gradient evaluation technique is developed, that incorporates elements of both the adjoint and direct sensitivity methods. Results demonstrate that the method is highly accurate and competitive with a full adjoint approach for a moderate number of design variables.     

Carbon Nanotubes: Biocompatibility of Immobilized Aligned Carbon Nanotubes (Small 8/2011)

In vivo host responses to an electrode‐like array of aligned carbon nanotubes (ACNTs) embedded within a biopolymer sheet are reported. This biocompatibility study assesses the suitability of immobilized carbon nanotubes for bionic devices. Inflammatory responses and foreign‐body histiocytic reactions are not substantially elevated when compared to negative controls following 12 weeks implantation. A fibrous capsule isolates the implanted ACNTs from the surrounding muscle tissue. Filamentous nanotube fragments are engulfed by macrophages, and globular debris is incorporated into the fibrous capsule with no further reaction. Scattered leukocytes are observed, adherent to the ACNT surface. These data indicate that there is a minimal local foreign‐body response to immobilized ACNTs, that detached fragments are phagocytosed into an inert material, and that ACNTs do not attract high levels of surface fouling. Collectively, these results suggest that immobilized nanotube structures should be considered for further investigation as bionic components.     

The behaviour of non-ideal explosives in the Ballistic Mortar

Abstract

An analysis has been developed for the Ballistic Mortar test based on classical mechanics and a two stage chemical reaction rate model. Non-ideal behaviour of the composition was modelled by partial energy release during the detonation phase and secondary exothermic processes during the expansion phase. Erosive grain burning and time delayed reactions were both considered. Gas loss from the mortar cavity due to leakage was included. Predicted mortar performance of several ideal and non-ideal explosives were in good agreement with experimental values. The effects of slow and incomplete reaction of non-ideal compositions have been demonstrated, and it has been shown that measurement of mortar throw angle alone is insufficient to determine the performance of a composition. The model has been used to elucidate the reaction rate behaviour of Ammonium Nitrate and Aluminium in commercial explosives.     

Void size dependence of the steady detonation properties of emulsion explosives by

Abstract

Detonation velocity/cartridge diameter measurements have been made on a series of emulsion explosives containing three size fractions of sieved glass microballoons and at two composition density ranges. The data is analysed using a slightly divergent flow code. The results show the interaction between the kinetics and hydrodynamics of the detonation process.