Energy and raw material consumption analysis of powder bed fusion: case study: CNC machining and laser additive manufacturing

Laser additive manufacturing (LAM), known also as 3D printing, is a powder bed fusion (PBF) type of additive manufacturing (AM) technology used to manufacture metal parts layer by layer by assist of laser beam. The development of the technology from building just prototype parts to functional parts is due to design flexibility. And also possibility to manufacture tailored and optimised components in terms of performance and strength to weight ratio of final parts. The study of energy and raw material consumption in LAM is essential as it might facilitate the adoption and usage of the technique in manufacturing industries. The objective this thesis was find the impact of LAM on environmental and economic aspects and to conduct life cycle inventory of CNC machining and LAM in terms of energy and raw material consumption at production phases. Literature overview in this thesis include sustainability issues in manufacturing industries with focus on environmental and economic aspects. Also life cycle assessment and its applicability in manufacturing industry were studied. UPLCI-CO2PE! Initiative was identified as mostly applied exiting methodology to conduct LCI analysis in discrete manufacturing process like LAM. Many of the reviewed literature had focused to PBF of polymeric material and only few had considered metallic materials. The studies that had included metallic materials had only measured input and output energy or materials of the process and compared to different AM systems without comparing to any competitive process. Neither did any include effect of process variation when building metallic parts with LAM. Experimental testing were carried out to make dissimilar samples with CNC machining and LAM in this thesis. Test samples were designed to include part complexity and weight reductions. PUMA 2500Y lathe machine was used in the CNC machining whereas a modified research machine representing EOSINT M-series was used for the LAM. The raw material used for making the test pieces were stainless steel 316L bar (CNC machined parts) and stainless steel 316L powder (LAM built parts). An analysis of power, time, and the energy consumed in each of the manufacturing processes on production phase showed that LAM utilises more energy than CNC machining. The high energy consumption was as result of duration of production. Energy consumption profiles in CNC machining showed fluctuations with high and low power ranges. LAM energy usage within specific mode (standby, heating, process, sawing) remained relatively constant through the production. CNC machining was limited in terms of manufacturing freedom as it was not possible to manufacture all the designed sample by machining. And the one which was possible was aided with large amount of material removed as waste. Planning phase in LAM was shorter than in CNC machining as the latter required many preparation steps. Specific energy consumption (SEC) were estimated in LAM based on the practical results and assumed platform utilisation. The estimated platform utilisation showed SEC could reduce when more parts were placed in one build than it was in with the empirical results in this thesis (six parts).

Early detection of metabolic and energy disorders by thermal time series stochastic complexity analysis

Maintenance of thermal homeostasis in rats fed a high-fat diet (HFD) is associated with changes in their thermal balance. The thermodynamic relationship between heat dissipation and energy storage is altered by the ingestion of high-energy diet content. Observation of thermal registers of core temperature behavior, in humans and rodents, permits identification of some characteristics of time series, such as autoreference and stationarity that fit adequately to a stochastic analysis. To identify this change, we used, for the first time, a stochastic autoregressive model, the concepts of which match those associated with physiological systems involved and applied in male HFD rats compared with their appropriate standard food intake age-matched male controls (n=7 per group). By analyzing a recorded temperature time series, we were able to identify when thermal homeostasis would be affected by a new diet. The autoregressive time series model (AR model) was used to predict the occurrence of thermal homeostasis, and this model proved to be very effective in distinguishing such a physiological disorder. Thus, we infer from the results of our study that maximum entropy distribution as a means for stochastic characterization of temperature time series registers may be established as an important and early tool to aid in the diagnosis and prevention of metabolic diseases due to their ability to detect small variations in thermal profile.

Relations entre l'excès de poids, la qualité de l'alimentation et l'insécurité alimentaire chez les Premières Nations vivant sur les réserves de la Colombie-Britannique, Canada

La prévalence de l’excès de poids (EP) est en pleine croissance à travers le monde. Au Canada, elle serait de 59,1% dans la population générale, dont 23,1% d’obésité et 36,0% d’embonpoint. Ces pourcentages sont encore plus élevés dans la population autochtone, en plus d’une forte prévalence d’insécurité alimentaire (IA) et une alimentation en transition vers de moins en moins de nourritures traditionnelles, et de plus en plus de nourritures commerciales de faible densité nutritionnelle. L’Organisation mondiale de la santé (OMS) recommande des initiatives pour documenter le statut sanitaire de cette population afin d’orienter les actions pouvant prévenir les conséquences négatives sur la santé. Notre étude visait donc à décrire les phénomènes de l’EP et de l’IA chez les Premières Nations (PN) adultes de 19 ans et plus, vivant sur les réserves en Colombie-Britannique (CB). Cet échantillon est en effet le premier d’un projet de 10 ans dénommé « First Nations Food, Nutrition and Environment Study » ou (FNFNES), visant à documenter l’état nutritionnel et l’exposition à certains contaminants chez les PN vivant au sud du 60ème parallèle au Canada. Plus particulièrement, cette thèse cherche à associer trois dimensions de la santé, soit l’EP, la qualité de l’alimentation (QA) et l’IA. Nous avons voulu en effet vérifier dans le contexte des PN de la CB: 1) si une QA inadéquate serait associée à un risque plus élevé d’EP; 2) si l’IA des ménages serait associée à une qualité inadéquate de l’alimentation; et 3) si la QA et l’IA expliqueraient ensemble la présence d’EP. A l’issue des analyses (univariées, bivariées, MANOVA et régressions logistiques) de nos données transversales colligées en 2008/2009, les prévalences respectives chez les femmes (n = 493) et les hommes (n = 356) adultes étaient de 44,8% et 35,4% pour l’obésité, de 31,6% et 41,3% pour l’embonpoint, soit un total de 76,4% et 76,7% d’EP. Elles étaient de 39,3% et de 34,8% pour l’IA. Seuls 42,4% des femmes et 43,8% des hommes avaient un accès suffisant aux aliments traditionnels. Après ajustement pour les variables sociodémographiques et du mode de vie, les résultats des analyses multivariées ont montré ii que bien que les prévalences d’EP et d’IA soient assez similaires dans les deux sexes, les processus reliant l’EP, la QA et l’IA seraient différents. En effet, chez les femmes, l’EP serait expliqué par une QA compromise par des apports énergétiques relativement élevés (RC = 2,26; IC: 1,13 - 4,52), la consommation fréquente des boissons gazeuses (pour l’embonpoint, RC = 2,70; IC: 1,11 - 6,56 et pour l’obésité, RC = 2,53; IC: 1,05 - 6,09), en synergie avec l’inactivité physique (RC = 0,52; IC: 0,28 – 0,98 pour le groupe à activité modérée, et RC = 0,36; IC: 0,18 – 0,72 pour le groupe le plus actif), tandis que les produits céréaliers (RC = 0,35; IC: 0,16 - 0,75) et le lait et substituts (RC = 0,40; IC: 0,16 - 0,95) joueraient un rôle protecteur contre l’EP. D’autre part, l’IA des ménages influencerait la QA (à travers les gras saturés, p = 0,02) mais lorsque les trois variables sont étudiées ensemble, seules des dimensions de la QA apparaissent associées à l’EP. Par contre chez les hommes, le seul facteur alimentaire associé à l’EP est le pain blanc mais dans un rôle protecteur (pour l’embonpoint, RC = 0,38; IC: 0,18 - 0,76 et pour l’obésité, RC = 0,36; IC: 0,16 - 0,80); de même, lorsque les trois variables sont étudiées ensemble, l’IA joue un rôle protecteur de l’EP, dans un contexte de tabagisme relativement élevé et également protecteur, ce qui n’expliquerait pas la forte prévalence d’EP observée chez les hommes PN vivant sur les réserves de la CB. Des études plus approfondies et sur des échantillons plus grands seraient nécessaires pour mieux cerner la nature des relations mais d’ores et déjà, notre travail suggère que des effets positifs sur l’EP peuvent être attendus des politiques et programmes visant à réduire la consommation des boissons gazeuses et l’inactivité physique, et à encourager la consommation des produits céréaliers et de lait et substituts chez les femmes. Quant aux hommes, les conclusions de notre étude ne nous permettent pas encore de formuler des recommandations précises. Alors, les comportements santé recommandés aux femmes devraient être généralisés aux hommes en attendant les conclusions d’autres études.

Femtosecond imaging-mode laser-induced breakdown spectroscopy

Many nonlinear optical microscopy techniques based on the high-intensity nonlinear phenomena were developed recent years. A new technique based on the minimal-invasive in-situ analysis of the specific bound elements in biological samples is described in the present work. The imaging-mode Laser-Induced Breakdown Spectroscopy (LIBS) is proposed as a combination of LIBS, femtosecond laser material processing and microscopy. The Calcium distribution in the peripheral cell wall of the sunflower seedling (Helianthus Annuus L.) stem is studied as a first application of the imaging-mode LIBS. At first, several nonlinear optical microscopy techniques are overviewed. The spatial resolution of the imaging-mode LIBS microscope is discussed basing on the Point-Spread Function (PSF) concept. The primary processes of the Laser-Induced Breakdown (LIB) are overviewed. We consider ionization, breakdown, plasma formation and ablation processes. Water with defined Calcium salt concentration is used as a model of the biological object in the preliminary experiments. The transient LIB spectra are measured and analysed for both nanosecond and femtosecond laser excitation. The experiment on the local Calcium concentration measurements in the peripheral cell wall of the sunflower seedling stem employing nanosecond LIBS shows, that nanosecond laser is not a suitable excitation source for the biological applications. In case of the nanosecond laser the ablation craters have random shape and depth over 20 µm. The analysis of the femtosecond laser ablation craters shows the reproducible circle form. At 3.5 µJ laser pulse energy the diameter of the crater is 4 µm and depth 140 nm for single laser pulse, which results in 1 femtoliter analytical volume. The experimental result of the 2 dimensional and surface sectioning of the bound Calcium concentrations is presented in the work.

Alternatives to linear analysis of energy balance data from lactating dairy cows

The current energy requirements system used in the United Kingdom for lactating dairy cows utilizes key parameters such as metabolizable energy intake (MEI) at maintenance (MEm), the efficiency of utilization of MEI for 1) maintenance, 2) milk production (k(l)), 3) growth (k(g)), and the efficiency of utilization of body stores for milk production (k(t)). Traditionally, these have been determined using linear regression methods to analyze energy balance data from calorimetry experiments. Many studies have highlighted a number of concerns over current energy feeding systems particularly in relation to these key parameters, and the linear models used for analyzing. Therefore, a database containing 652 dairy cow observations was assembled from calorimetry studies in the United Kingdom. Five functions for analyzing energy balance data were considered: straight line, two diminishing returns functions, (the Mitscherlich and the rectangular hyperbola), and two sigmoidal functions (the logistic and the Gompertz). Meta-analysis of the data was conducted to estimate k(g) and k(t). Values of 0.83 to 0.86 and 0.66 to 0.69 were obtained for k(g) and k(t) using all the functions (with standard errors of 0.028 and 0.027), respectively, which were considerably different from previous reports of 0.60 to 0.75 for k(g) and 0.82 to 0.84 for k(t). Using the estimated values of k(g) and k(t), the data were corrected to allow for body tissue changes. Based on the definition of k(l) as the derivative of the ratio of milk energy derived from MEI to MEI directed towards milk production, MEm and k(l) were determined. Meta-analysis of the pooled data showed that the average k(l) ranged from 0.50 to 0.58 and MEm ranged between 0.34 and 0.64 MJ/kg of BW0.75 per day. Although the constrained Mitscherlich fitted the data as good as the straight line, more observations at high energy intakes (above 2.4 MJ/kg of BW0.75 per day) are required to determine conclusively whether milk energy is related to MEI linearly or not.

Resolving the energy paradox of chaperone/usher-mediated fibre assembly

Periplasmic chaperone/usher machineries are used for assembly of filamentous adhesion organelles of Gram-negative pathogens in a process that has been suggested to be driven by folding energy. Structures of mutant chaperone-subunit complexes revealed a final folding transition (condensation of the subunit hydrophobic core) on the release of organelle subunit from the chaperone-subunit pre-assembly complex and incorporation into the final fibre structure. However, in view of the large interface between chaperone and subunit in the pre-assembly complex and the reported stability of this complex, it is difficult to understand how final folding could release sufficient energy to drive assembly. In the present paper, we show the X-ray structure for a native chaperone-fibre complex that, together with thermodynamic data, shows that the final folding step is indeed an essential component of the assembly process. We show that completion of the hydrophobic core and incorporation into the fibre results in an exceptionally stable module, whereas the chaperone-subunit preassembly complex is greatly destabilized by the high-energy conformation of the bound subunit. This difference in stabilities creates a free energy potential that drives fibre formation.

Structure and biogenesis of the capsular F1 antigen from Yersinia pestis: Preserved folding energy drives fiber formation

Most gram-negative pathogens express fibrous adhesive virulence organelles that mediate targeting to the sites of infection. The F1 capsular antigen from the plague pathogen Yersinia pestis consists of linear fibers of a single subunit (Caf1) and serves as a prototype for nonpilus organelles assembled via the chaperone/usher pathway. Genetic data together with high-resolution X-ray structures corresponding to snapshots of the assembly process reveal the structural basis of fiber formation. Comparison of chaperone bound Caf1 subunit with the subunit in the fiber reveals a novel type of conformational change involving the entire hydrophobic core of the protein. The observed conformational change suggests that the chaperone traps a high-energy folding intermediate of Caf1. A model is proposed in which release of the subunit allows folding to be completed, driving fiber formation.

‘Nudging’ energy users: regulatory measures to address the risk of aggregate peak demand in European electricity markets

For decades regulators in the energy sector have focused on facilitating the maximisation of energy supply in order to meet demand through liberalisation and removal of market barriers. The debate on climate change has emphasised a new type of risk in the balance between energy demand and supply: excessively high energy demand brings about significantly negative environmental and economic impacts. This is because if a vast number of users is consuming electricity at the same time, energy suppliers have to activate dirty old power plants with higher greenhouse gas emissions and higher system costs. The creation of a Europe-wide electricity market requires a systematic investigation into the risk of aggregate peak demand. This paper draws on the e-Living Time-Use Survey database to assess the risk of aggregate peak residential electricity demand for European energy markets. Findings highlight in which countries and for what activities the risk of aggregate peak demand is greater. The discussion highlights which approaches energy regulators have started considering to convince users about the risks of consuming too much energy during peak times. These include ‘nudging’ approaches such as the roll-out of smart meters, incentives for shifting the timing of energy consumption, differentiated time-of-use tariffs, regulatory financial incentives and consumption data sharing at the community level.

Thermoelectric materials: a new rapid synthesis process for non-toxic and high-performance tetrahedrite compounds

The feasibility to synthesize, in large quantity, pure and non-toxic tetrahedrite compounds using high-energy mechanical-alloying from only elemental precursors is reported in the present paper for the first time. Our processing technique allows a better control of the final product composition and leads to high thermoelectric performances (ZT of 0.75 at 700 K), comparable to that reported on sealed tube synthesis samples. Combined with spark plasma sintering, the production of highly pure and dense samples is achieved in a very short time, at least 8 times shorter than in conventional liquid-solid-vapor synthesis process. The process described in this paper is a promising way to produce high performance tetrahedrite materials for cost-effective and large-scale thermoelectric applications.

Particle acceleration and magnetic field structure in PKS 2155-304: optical polarimetric observations

In this paper, we present multiband optical polarimetric observations of the very-high energy blazar PKS 2155-304 made simultaneously with a HESS/Fermi high-energy campaign in 2008, when the source was found to be in a low state. The intense daily coverage of the data set allowed us to study in detail the temporal evolution of the emission, and we found that the particle acceleration time-scales are decoupled from the changes in the polarimetric properties of the source. We present a model in which the optical polarimetric emission originates at the polarized mm-wave core and propose an explanation for the lack of correlation between the photometric and polarimetric fluxes. The optical emission is consistent with an inhomogeneous synchrotron source in which the large-scale field is locally organized by a shock in which particle acceleration takes place. Finally, we use these optical polarimetric observations of PKS 2155-304 at a low state to propose an origin for the quiescent gamma-ray flux of the object, in an attempt to provide clues for the source of its recently established persistent TeV emission.

Upper limit on the cosmic-ray photon flux above 10(19) eV using the surface detector of the Pierre Auger Observatory

A method is developed to search for air showers initiated by photons using data recorded by the surface detector of the Auger Observatory. The approach is based on observables sensitive to the longitudinal shower development, the signal risetime and the curvature of the shower front. Applying this method to the data, tipper limits on the flux of photons of 3.8 x 10(-3), 2.5 x 10(-3), and 2.2 x 10(-3) km(-2) sr(-1) yr(-1) above 10(19) eV, 2 x 10(19) eV, and 4 x 10(19) eV are derived, with corresponding limits on the fraction of photons being 2.0%, 5.1%, and 31% (all limits at 95% c.l.). These photon limits disfavor certain exotic models of sources of cosmic rays. The results also show that the approach adopted by the Auger Observatory to calibrate the shower energy is not strongly biased by a contamination from photons. (C) 2008 Elsevier B.V. All rights reserved.

Observation of an Antimatter Hypernucleus

Nuclear collisions recreate conditions in the universe microseconds after the Big Bang. Only a very small fraction of the emitted fragments are light nuclei, but these states are of fundamental interest. We report the observation of antihypertritons-comprising an antiproton, an antineutron, and an antilambda hyperon-produced by colliding gold nuclei at high energy. Our analysis yields 70 +/- 17 antihypertritons (3/Lambda(H) over bar) and 157 +/- 30 hypertritons ((3)(Lambda)H). The measured yields of (3)(Lambda)H (3/Lambda(H) over bar) and (3)He ((3)(He) over bar) are similar, suggesting an equilibrium in coordinate and momentum space populations of up, down, and strange quarks and antiquarks, unlike the pattern observed at lower collision energies. The production and properties of antinuclei, and of nuclei containing strange quarks, have implications spanning nuclear and particle physics, astrophysics, and cosmology.