Materials Engineering

The overall objective is to present a procedure based on a Couette analogy to quantitavely analyse torque/rotor speed data in order to extract viscosity/ shear-rate curves using non-conventional geometry. Diphasic flows of energetic concentrated suspensions of melt-cast insensitive explosives exhibit particular rheology properties. Characterization of these complex fluids may be a challenging task when conventional rheometers are used. Placing these dense suspensions in a classic cylindrical geometry may occur in a partial destruction of internal structure. To avoid that, Mixer-Type rheometry, consisting of a mixing device with more complex geometry rotating in a fluid contained in cylindrical tank, is investigate. To evaluate the rheological parameters of our mixing rheometer, we used five Newtonian fluids. After the calibration of the apparatus, rheological characterizations and destruction tests are carried out on five XF13333 formulations. The unique parameter which changes in these formulations is the batch’s origin of a secondary explosive: the 3-nitro-1,2,4-triazole-5-one (called NTO). Determination of Ostwald’s parameters and viscosity evaluation during a resting time make it possible to apprehend the flow quality of our energetic formulations. Evolutions of consistency and flow indexes with maximum packing density (calculated with De Larrard model) are shown to explain the rheological behaviour evolution.

Statistical design of experiments was used to investigate the effect the process parameters on electrophoretic deposition (EPD) of alumina onto steel substrates from its suspension in iso-propanol. The process parameters considered were (i) concentration of particles in the suspension (solid loading), (ii) electrode separation, (iii) applied potential, and (iv) deposition time on the quantity of ceramic particles electrophoretically deposited. A 2^4 full factorial matrix, with four repetitions of the center point, was used to develop the predictive regression equation for deposition of alumina per unit area of the electrode in the design space. The results show that particle concentration has the most dominant effect with more than 50% contribution to the deposited amount. A good correlation was obtained between predicted and experimental values suggesting that the model can predict data accurately in the experimental matrix.

We challenged the educational community. The Brits responded.

A number of papers were presented supporting the notion of inducting the racing ethic into academia. A Chair and Research Center, along with a Journal of Record were recommended.

This presentation to the Motorsports Engineering Conference of SAE was well-received, but not, apparently, noticed by those academics not in contact with such sessions.

It is up to us concerned with exploiting the racing work ethic in academia, to convince the 'unwashed' that there are great benefits to be reaped.

Racers are not noted for self-promotion. A great deal of work must be done to create a taxonomy of motorsports, and rationalize those human values demonstrated in the sport, so that they can be readily understood, and employed in education.

Subsequent papers have pointed to the same issues. Posting them to academia.edu may result in creating a wider constituency and enhance the prospects for adoption of the racing work ethic into academia.

It is now recognized that model predictive control (MPC) is an interesting alternative for real-time control of industrial processes. In the meantime, some problems do still remain in progress: for theoretical aspects, the a priori guarantee of the stability and for the practical aspects, the guarantee of sufficient time to solve to optimization problem at each sampled time positions. In this paper, we propose a global method that aims to reduce the on-line calculation time due to the PDE model based optimization task resolution. It is addressed for a particular class of systems not very often studied in this context: systems described by partial differential equations (PDEs) which are, in the present case, nonlinear and parabolic. In order to decrease the computational burden, the nonlinear PDE system is solved off-line. Then, a linearized PDE model around the previous off-line behavior is used to find the optimal variations for the on-line predictive control. The real-time control application given is concerned with a infrared drying process of painting film.

In emulsion polymerization processes, the surfactant concentration plays an impor- tant role in the latex stability, reaction kinetics and particle size distribution (PSD). Controlling the free surfactant concentration in the aqueous phase ensures the stability of the latex and the control of the micellar nucleation rate. The PSD is determined by particle nucleation, growth and stability which are highly nonlinear behaviors. The PSD affects the polymer rheology, adhesion, optical properties and mechanical strength. This work deals with the model predictive control (MPC) of free surfactant concentration using the surfactant feed rate as a control variable. The used strategy is a global method that aims to reduce the on-line calculation time due to the partial differential equations (PDE) model based optimization task resolution. In order to decrease the computational burden, the nonlinear PDE system is solved off-line. Then, a linearized PDE model around the previous off-line behavior is used to find the optimal variations for the on-line predictive control.

Microstructured optical fibres (MOFs) are an important new technology exhibiting unique and tunable optical properties. While fibre optics generally exploit silica glass, the use of fluoride glasses yields particular advantages including theoretical low losses and a wide wavelength range of transmission. A fluoride glass MOF combines the unique properties of both technologies in a novel fiber. Widespread adoption of the technology has been limited in part by high experimental attenuations due to extrinsic factors such as sidewall scattering. Estimating the loss due to sidewall scattering requires accurate determination of sidewall roughness, which has not yet been reported for fluorine glass MOFs. Here we report the use of AFM to characterise the roughness of the inside surface of a hole in both a ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) and AZYRN (AlF3-ZrF4-YF4-CaF2-MgF2-SrF2-BaF2-NaCl) MOF. RMS roughness values of 7Å and 76Å for the respective ZBLAN and AZYRN fibres were obtained.

Techniques for producing needle-shaped specimens suitable for atom probe analysis from a bulk material via electropolishing and ion beam milling were investigated. A 7020 Aluminium alloy of composition Al-4.8%Zn-1.3%Mg (%wt, as cast), an Aluminium alloy of composition Al-1.1%Cu-0.5%Mg (%wt, as cast), and a spinodal Fe-Ni-Mn-Al alloy of composition 30%Fe-20%Ni-25%Mn-25%Al (%wt, as cast and treated for 1 hour at 1005˚C then air cooled) were explored. Procedures were characterised in detail using a CCD camera and SEM microscopy and parameters for the most efficient preparation methods were deduced. Extensive atom probe data was obtained from the 7020 specimen.

The effect of metallurgical parameters on the Brinell hardness of heat-treated 319 type alloys was investigated, to quantify the effects of alloying elements (Mg, Fe, Mn, Sr) and aging parameters on the hardness of heat-treated 319 alloys containing alpha-Fe or beta-Fe intermetallics. The corresponding alloy melts (at 750°C +/- 5°C) were cast into preheated graphite-coated metallic molds to prepare samples for hardness measurements. These samples were heat treated (solution treatment: 8h@495°C; quenching in warm water (65°C); aging at 155°, 180°, 200° and 220°C for 4h). Different aging times (2, 4, 6 and 8h) were also studied for the 180° and 220°C aging temperatures. Hardness measurements were made using a Brinell hardness tester (10 mm diameter ball and 500 kgf). Experimental correlations between the metallurgical and heat treatment parameters and the hardness values obtained were analyzed using factorial analysis (2k factorial design). For this, two levels of Mg (0.1 and 0.28 wt%), Fe-intermetallics (2% and 5%), Sr (0 and 200 ppm - non-modified and modified conditions), and two aging temperatures (180° and 220°C) and times (2h and 8h) were selected. The results obtained are in agreement with the experimental findings for these aging times and temperatures. It is found that the hardness increases with increasing Mg content and volume fraction of -Fe intermetallics, but decreases with Sr modification and with increasing aging temperature and time.

The crystal structures of co-crystals of two systems of chiral carboxylic acids, optically active and racemic 2-phenylpropionic acid and 2-phenylbutyric acid, with isonicotinamide are reported to investigate the effects of the chirality of the chiral carboxylic acids on the melting point of the co-crystal complexes. It was found that the racemic co-crystal has a higher melting point than the optically active co-crystal, which correlates with the denser packing arrangement inherent in centrosymmetric space groups.

Three inorganic–organic layered perovskite-type hybrids of the general formula [(CnH2n + 1NH3)2PbI4], n = 4, 5 and 6, display a number of reversible first-order phase transitions in the temperature range from 256 to 393 K. [(C4H9NH3)2PbI4] has a single phase transition, [(C5H11NH3)2PbI4] has two phase transitions and [(C6H13NH3)2PbI4] has three phase transitions. In all three cases, the lowest-temperature phase transition is thermochromic and the crystals change colour from yellow in their lowest-temperature phase to orange in their higher-temperature phase for [(C4H9NH3)2PbI4] and [(C6H13NH3)2PbI4], and from orange to red for [(C5H11NH3)2PbI4]. The structural details associated with this phase transition have been investigated via single-crystal X-Ray diffraction, SC-XRD, for all three compounds.

The title compound, [NH3C6H4NH3][ZnI4] . 2H2O, crystallizes as an organic-inorganic hybrid. The ionic layer consists of isolated ZnI4 tetrahedra. The hydrocarbon layer has two symmetry independant para-phenylenediammonium cations that link to the ionic layer via hydrogen bonding. Two waters of hydration lie between the ZnI4 and the two cations.

The crystal stucture of p-nitroaniline hydrobromide,(O2NC6H4NH3)+.Br- exhibits ionic layers separated by hydrocarbon layers. The hydrocarbon layer stacks head-to-tail but no pi-pi interactions are observed. In the inorganic layer, the ammonium group, bromide anion and nitro group interact to form a three dimensional hydrogen-bonded network. The structure is compared to the related material (O2NC6H4NH3)+.Cl-.

There have been increased interests in the research on mechanical and control system of underwater vehicles in the recent past. These ongoing research efforts are motivated by more pervasive applications of such vehicles including seabed oil and gas explorations, scientific deep ocean surveys, military purposes, ecological and waters environmental studies, and also for entertainments. However, the performance of underwater vehicles with screw type propellers is not prospective in terms of its efficiency and maneuverability. The main weaknesses of this kind of propellers are the production of vortices and sudden generation of thrust forces which make the control of the position and motion difficult.
On the other hand, fishes and other aquatic animals are efficient swimmers, posses high maneuverability, are able to follow trajectories, can efficiently stabilize themselves in currents and surges, create less wakes than currently used underwater vehicle, and also have a noiseless propulsion. The fish’s locomotion mechanism is mainly controlled by its caudal fin and paired pectoral fins part. They are classified into BCF (Body and/or Caudal Fin) and MPF (Median and/or paired Pectoral Fins). The study of highly efficient swimming mechanisms of fish can inspire a better underwater vehicles thruster design and its mechanism.
There have not been many studies on underwater vehicles or fish robots using paired pectoral fins as thruster. The work presented in this paper represents a contribution in this area covering study, design and implementation of locomotion mechanisms of paired pectoral fins in a fish robot. The performance and viability of the biomimetic method for underwater vehicles are highlighted through in-water experiment of a robotic fish.

The formulations of existing free dendritic growth models were compared, and an extended model was proposed that employs a subregular solution model to compute the driving force for dendritic growth without Henrian restrictions. These models were also applied to a Ag-15 mass pct Cu alloy to numerically compare their predictions. Models that address only the thermal, solutal, and curvature supercoolings do not properly account for the interface kinetics, even with modifications with the kinetic partition coefficient and liquidus slope. It is only in models that account for the interfacial driving force, −ΔG*, that the kinetic supercooling is properly addressed. All of the models in comparison yield numerically similar predictions for the solutal growth regime, but models that employ the kinetic partition coefficient and liquidus slope, but do not address the interfacial driving force, fail to correctly describe the thermal control regime. The solutal-to-thermal transition is characterized by a rapid increase of interfacial driving force, which causes the tip temperature T* to increase with increasing growth rate V. The criterion for the transition stage is given as dln(−ΔG*)/dlnV>1.

The synthesis, electrochemical and spectroscopic properties of a series of thiophene-substituted 1,3-dithiole-2-ones is described. The derivatives Th-3,3, Th-2,2, Th-2,3, Th-3,3(2,2′-Me), and Th3,3-(2,5,2′,5′-Me), have been successfully polymerized by cyclic voltammetry. From the UV−visible spectra of the neutral films, it was determined that PTh-3,3, PTh-2,2 and PTh-2,3 have a bandgap of 2.04, 2.30, and 2.18 eV, respectively. The voltammetric response of Th-3,3(2,2′-Me) was noticeably different from the other polymers. The SNIFTIRS data suggested that Th-3,3(2,2′-Me) was formed by bonding via the β-positions of the thiophene ring, resulting in a poorly conductive polymer. The in situ solid-state modification of PTh-3,3 to produce a new TTF-derivatized polythiophene was carried out. The cyclic voltammetry of the modified polymer confirmed the inclusion of TTF into the backbone of the film.

"At the end of their service life, wood-based panels become eventually waste wood. Deploying in landfills is no longer considered as an acceptable solution for their handling due to the high organic load included. The recycling of this waste to be employed as raw material for the wood panel industry, which traditionally makes use of wood processing residues, has hence gained more importance and been examined from earlier times.
Technical problems and the lack of enforcing legislative regulations have delayed, however, the industrial implementation of the new technologies proposed. Recent research efforts
enabled the development of a new process for the recycling of end-use wood panels into new marketable fibreboards. This patent pending process is based on the refiner technique and
allows the use of mixtures of fresh wood and waste panel chips as a raw material for dry process fibreboard production. The process is applicable in existing fibreboard plants with only minor operation modifications and therefore, there is no need of major capital investment in additional equipment to effect the recycling. At the refining stage, chemical agents are employed and the process enables the use of significant amounts of waste
material replacing over 20% of the wood feed and providing significant savings. The aim of the present work was to validate the industrial applicability of the new process in the recycling of waste medium-density fibreboards. The new fibreboards obtained during the industrial scale tests were of acceptable quality, and the testing results revealed that under
conventional gluing and pressing conditions, the process effectively recycles the waste boards into new ones at least at 25% wood substitution level. Further validation and
optimisation work is underway in the direction of using other waste panel types and also increasing the level of waste in the feed material."

A statistical model for prediction of the maximum extent of the swelling of wood in organic liquids is proposed in this work. Solvent basicity, solvent molecular volume, and density of wood appeared to be the most important parameters in the proposed model. The addition of the hydrogen bonding capability parameter did not significantly improve the model.

"The rate and maximum swelling of several North American wood species in water have been obtained with a computer interfaced linear variable displacement transformer. Since wood swells extremely fast in water even at room temperature, this apparatus made it possible for the first time, to obtain accurate rate data on the swelling of wood in water. The strict linear dependence of swelling on the temperature suggests a chemical mechanism.
The activation energies obtained from Arrhenius plots ranged from 32.2 KJ/ mole for sitka spruce to 47.6 KJ/ mole for sugar maple. Although the two hardwoods exhibited greater maximum tangential swelling compared with the two softwoods, the maximum swelling appears to be correlated with the wood density. Generally both the rate and maximum swelling of the woods were increased by removal of extractives and the activation energies were reduced."

The structural, optical, and electrical transformations induced by hydrogen absorption and/or desorption in Mg-Ti thin films prepared by co-sputtering of Mg and Ti are investigated. Highly reflective in the metallic state, the films become highly absorbing upon H absorption. The reflector-to-absorber transition is fast, robust, and reversible over many cycles. Such a highly absorbing state hints at the coexistence of a metallic and a semiconducting phase. It is, however, not simply a composite material consisting of independent MgH2 and TiH2 grains. By continuously monitoring the structure during H uptake, we obtain data that are compatible with a coherent structure. The average structure resembles rutile MgH2 at high Mg content and is fluorite otherwise. Of crucial importance in preserving the reversibility and the coherence of the system upon hydrogen cycling is the accidental equality of the molar volume of Mg and TiH2. The present results point toward a rich and unexpected chemistry of Mg-Ti-H compounds.

The project discussed in this paper has been conducted as part of the Autonomatic research cluster based at University College Falmouth. The cluster is focused on research projects that explore the use of digital production technologies within the context of designer maker and craft practice.

My project is concerned with developing more direct control of processes that are typically automated by CAD software and CAM tools. I believe the use of these standardised tools limit the ability of the maker to create unique visual vocabularies.

It is possible to view the aesthetic qualities emerging in the new genre of ‘digital craft’ - such as the use of triangulation and the quality of line produced by generic pre-set machine parameters - as a temporary phase in the digital craft timeline. As more makers adopt digital technologies, we may discover that these visual aesthetic qualities are more attributable to the technology than the maker rather than being understood as unique. The author believes it is therefore important for makers wishing to further their practice in this field to seek ways in which they can gain greater control over the processes and tools they are using.

This paper presents research that explores ways in which programmed mathematical elements in 3D CAD can be deconstructed and manipulated throughout the design and production phases. Employing an iterative designing and making process I have used this ‘hand’ manipulated CAD data to drive CNC machine tools in highly specified ways. This has lead to an in depth understanding of the inter-relationship between CAD and CAM as intrinsic to the development of unique aesthetic qualities. The development of a dialogue between CAD code and CNC tooling has resulted in a greater level of control enabling the realisation of complex and completely controlled patterning on 3D forms that go beyond the restrictions of standard toolsets.

This research has resulted in a range of 3D aluminium sample pieces that I have used to create a visual knowledge bank which documents the relationship between software input, machine parameters and their effects on the visual form. This knowledge has been applied to my working digital design practice enabling me to create aluminium platters and beakers that counter the affects of automation.

This paper aims to offer other makers methods which allow the potential for 'hacking' into code in order to expand the possibilities for control and creative engagement with digital tools and thereby offering more unique opportunities for developing visual vocabularies than using standard toolsets alone.

High-κ dielectrics have become a necessity for CMOS scaling. Various dielectrics have been tried as a replacement to SiO2. Hf-based dielectrics, which have been used with some success, have their own set of problems and are only a short term solution. In this scenario, the rareearth lanthanide metal oxides, principally La2O3, are being studied as a potential SiO2-substitute. This paper reviews the issues with SiO2 and other high-κ dielectrics, and discusses the properties of rare-earth oxides as favourable gatedielectrics, and describes the various fabrication techniques employed to obtain rare-earth oxide thin films. Fig. 3. C-V data for a [Al/PrOx/n-Si] MOS capacitor structure grown by ALD using Pr[N(SiMe3)2]3.Figure reproduced from [11].

The effect of the cooling rate on hardness and thermal conductivity in a metallurgical Jominy bar made of AISI 1018 steel, by means of a water end-quenched heat treatment process without diffusion-controlled case depth, is studied with photothermal radiometry (PTR). It is concluded that our two PTR techniques, common-mode rejection demodulation (CMRD) and conventional 50% duty-cycle square-wave frequency scan, are sensitive to low hardness values and gradients, unlike the high values all previous photothermal studies have dealt with to-date. Both PTR methods have yielded an anti-correlation between thermal conductivity and microhardness in this case as in previous cases with heat-treated and diffusion-controlled case depth profiles. It is shown that the cooling rate strongly affects both hardness and thermal conductivity in the Jominy-bar heat-treating process. © EDP Sciences.

We describe the synthesis of an end-functionalized copolymer of N-(2-hydroxypropyl)methacrylamide (HPMA) and N-hydroxysuccinimide methacrylate (NMS) by reversible addition-fragmentation chain transfer (RAFT) polymerization. To control the polymer composition, the faster reacting monomer (NMS) was added slowly to the reaction mixture beginning 30 min after initating the polymerization (ca. 16% HPMA conversion). One RAFT agent, based on azocyanopentanoic acid, introduced a -COOH group to the chain at one end. Use of a different RAFT agent containing a 4-amino-1,8-naphthalimide dye introduced a UV-vis absorbing and fluorescent group at this chain end. The polymers obtained had molecular weights of 30 000 and 20 000, respectively, and contained about 30 mol% NMS active ester groups.

As many practitiones know, compressed streams are very sensitive the transmission errors. Even a single error can have devastating effects and compromise all the data downstream . In fact, the non-resilience of adaptive data compression has been a practical drawback of its use in many applications. Joint source-channel coding [4, 1] has emerged as a possible solution to this problem. Usually, joint source-channel coding trades source bits for channel bits or vice versa, and more than often requires some adjustments in source coding and channel coding parts.

ANALYSIS of the deformation field consistent with a Prandtl stress distribution travelling with an advancing plane-strain crack reveals the functional form of the near tip crack profile in an elastic-plastic solid. The crack opening 6 is shown to have the form 6 N r In (const./r) at a distance r from the tip. This observation coupled with data generated from finite element investigations of growing cracks in small-scale yielding permits the construction of a relation characterizing the deformation at an extending crack tip. A ductile crack-growth criterion consisting of the attainment of a critical opening at a small characteristic material distance from the tip is adopted. Predictions of the stability of a growing crack for both small-scale yielding specimens and those subject to general yielding are discussed.

THIS PAPER is a study of the theoretical foundations of constitutive relations at finite strain for a class of solids exhibiting inelasticity as a consequence of specific structural rearrangements, on the microscale, of constituent elements of material. Metals deforming plastically through dislocation motion are of this class and form the primary application of the theory. The development is in terms of a general internal-variabIe thermodynamic formalism for description of the microstructural rearrangements, and it is shown how metal plasticity may be so characterized.

Chinese checkers is a game played on a hexagonal grid. This regular hexagonal tesselation is an artifact of Euclidean geometry that provides a fair playing eld only for games of two, three, four or six players. Hyperbolic geometry allows tessallations of the plane by regular polygons with any number of sides. Hyperbolic versions of the chinese checkers board permit fair games with ve, seven and even more players.

We describe a technique for addressing individual nanoscale wires with microscale control wires without using lithographic-scale processing to define nanoscale dimensions. Such a scheme is necessary to exploit sublithographic nanoscale storage and computational devices. Our technique uses modulation doping to address individual nanowires and self-assembly to organize them into nanoscale-pitch decoder arrays. We show that if coded nanowires are chosen at random from a sufficiently large population, we can ensure that a large fraction of the selected nanowires have unique addresses. For example, we show that lines can be uniquely addressesd over 99% of the time using no more than 2 2 log 2 ( ) + 11 address wires. We further show a hybrid decoder scheme that only needs to address = ( litho pitch nano pitch ) wires at a time through this stochastic scheme; as a result, the number of unique codes required for the nanowires does not grow with decoder size. We give an

Replacing parametrization of a domain with polyhedral approximations we give an optimal extension of the Divergence Theorem. Permitted domains of integration, called chainlets, range from smooth submanifolds to structures that may not be locally Euclidean and have no tangent vectors defined anywhere. One may still calculate divergence over the domain, and flux through its boundary which itself may have no normal vectors defined anywhere.

Cet article analyse la possibilité d’utiliser les nanocornets de carbone (ou nanohorns) comme solution au problème du stockage massif d’hydrogène. Alors qu’une quantité non négligeable d’hydrogène peut être adsorbée par les nanotubes de carbone mono-feuillets (SWNT) sous une pression de 100 bars et à une température de 10 K, il s’avère que pratiquement toute cette quantité s’échappe du matériau lorsque celui-ci est remis dans les conditions ambiantes, et seulement une infime partie est réadsorbée lorsque la température est redescendue à 10 K. Les nanocornets de carbone mono-feuillets (SWNH), structures graphitiques se présentant sous l’aspect de fleurs de dahlia et se formant par agrégation de structures nanotubulaires, apparaissent a priori plus prometteurs puisque le processus d’adsorption semble réversible et la plupart de l’hydrogène libéré à température ambiante est réadsorbé quand la température est à nouveau abaissée. En plus, leurs performances peuvent encore être améliorées en jouant sur la pression, ou en décorant la surface avec des nanoparticules métalliques. Les travaux présentés ici se limitent aux matériaux bruts. Les aspects microscopiques de l’adsorption d’hydrogène dans les nanostructures de carbone sont discutés à partir d’expériences de diffusion de neutrons. Le comportement de l’hydrogène adsorbé dans les SWNT est comparé à celui dans les SWNH en utilisant d’une part l’analyse de la transition rotationnelle para-ortho qui donne accès à des informations sur l’interaction entre les molécules d’hydrogène et la matrice carbonée, et en étudiant d’autre part le pic quasi-élastique dont la largeur dépend de la mobilité translationnelle de l’hydrogène et permet de discriminer les fractions d'hydrogène mobile et immobile.

Despite limited literature discussing the global implications of molecular manufacturing (MM), the seeds for certain key debates are starting to be sown. They essentially mirror those
presented for current and near-term nanotechnology: 1. for what purposes will the technology be developed and used, by whom will it be created and owned, what is the nature of the risks it will bring, and what kind of impact will it have upon the global economy and developing world?

The realisation of MM’s central goals would undoubtedly lead to the most concentrated technological tsunami ever witnessed. The unpredictable nature of such a revolution makes answering the previous questions all the more difficult.

However, just as biotechnology is commonly used as a yardstick for nanotechnology evaluations (given the continuity of many social concerns and the relationship between existing biotechnology capabilities and the potential to develop nanotechnology), I argue here that the best way to set up the MM debate, in terms of its impact on developing countries, may be to look at developments and trends in nanotechnology. Central to such analysis is addressing the ways in which nanotechnology creates new possibilities for developing countries in terms of access to technology, potential benefits, risks, and shifting views of science and technology, as well as the imposing of new demands in terms of infrastructure and approaches to science.