Physical market determinants of the price of crude oil and the market premium

We analyze the determinants of the real price of crude oil by means of an equilibrium correction model over the last two decades where we focus on the aspects of the physical market that impact on the clearing price. We find that two cointegrating relations affect the changes in prices: one refers to OPEC's behavior, attempting to control prices using its market power and quotas; the other to the coverage rate of OECD expected future demand using inventory behaviors. We derive a forecasting equation for the change in oil prices which we use to assess the speculative elements of the price increases of the period 2000–05. We show that worries alien to the physical markets were the causes of the increase in oil prices and we quantify their overall impact.     

Co(II)(l-proline)2(H2O)2 solid complex: Characterization,magnetic properties,and DFT computations. Preliminary studies of its use as oxygen scavenger in packaging films

A solid Co^II complex with l-proline as ligand was synthesized and fully characterized using spectroscopic studies, magnetic data, and DFT calculations. Dioxygen scavenging properties were investigated by UV/Vis spectroscopy and oxymetry techniques. The Co-proline system presented very interesting properties in matter of oxygen absorption capacity both in solution and incorporated in a polymer matrix.     

Temporal Regionalization of 7-Day Low Flows in the St. Lawrence Watershed in Quebec (Canada)

Winter and summer 7-day low flows of eighteen natural rivers in the St. Lawrence River watershed of Quebec were analyzed over the period from 1934 to 2000. The rivers were first subdivided into three modes using principal component analysis. Two of these modes are located on the south shore of the St. Lawrence River, respectively south (Southeast mode) and north (East mode) of the 47°N, and the third (Southwest mode) is located on the north shore. The Southeast mode shows a significant increase in 7-day low flows in winter and summer due to increasing summer and fall precipitation, whereas the Southwest mode shows a significant decrease in summer 7-day low flows due to an increase in evapotranspiration. No significant change in winter and summer 7-day low flows is observed in the East mode. Results show that the variability of 7-day low flows and their link with climate indices are mainly seasonally dependent. The North Atlantic Oscillation (NAO) is the only index which is correlated to 7-day low flows in all three modes. This correlation is positive for north shore rivers and negative for south shore rivers. Furthermore, only north shore rivers are correlated to NAO in both winter and summer.     

Communicating (nature‐based) flood‐mitigation schemes using flood‐excess volume

As interest mounts in nature‐based solutions (NBS) for flood mitigation as complementary options to civil‐engineering measures, possible flood‐protection strategies have become more diverse and hence complicated to assess. We offer a straightforward and educational protocol targeted for effectiveness analysis and decision making involving stakeholder participation. It is based on the concept of flood‐excess volume (FEV), the volume exceeding a threshold and generating flood damage, and explores what fraction of FEV is reduced, and at what cost, by particular flood‐mitigation measures. Quantification and interpretation of cost scenarios are facilitated using a graphical display that is easy to understand and encapsulates concepts of flood magnitude, FEV and protection‐measures efficacy. It is exemplified for two recent extreme‐flood events on the River Calder in Mytholmroyd (Yorkshire, United Kingdom) and the River Brague in Biot (Alpes‐Maritimes, France). Each case has different flood‐mitigation measures such as natural water‐retention measures, tree planting, river‐bed widening, or use of reservoirs and floods walls. Our straightforward protocol enables fast, quantifiable and easy‐to‐understand exploration of protection strategies using multiple measures, and in doing so highlights the issue of NBS scalability.     

Sintering Behavior and Optical Properties of Yttria

Sintering in air of a pure yttria powder was investigated on green samples shaped by slip casting. The "relative density/grain size" trajectory has been drawn and hypotheses concerning the mechanisms controlling grain growth and densification were formulated. Samples were fully densified by an additional hot isostatic pressing step on pre-sintered samples. After optimal polishing, optical properties were measured in the UV, visible, and infrared ranges.     

Spark Plasma Sintering of fine alpha-silicon nitride ceramics with LAS for spatial applications

Many space systems such as satellite mirrors and their supporting structures require to be made from very low-thermal expansion materials combining both high hydrostability and relatively high mechanical properties. In this study, we have applied the “composite concept” in order to explore the possibility of fabricating near zero thermal expansion silicon nitride based ceramics. Consequently, a negative thermal expansion material belonged to the lithium aluminosilicate family (LAS powder crystallized under de β-eucryptite structure) was introduced in an alpha-silicon nitride fine powder (5 and 20 vol% of LAS) and the resulting composite system was sintered by Spark Plasma Sintering (SPS) at 1400 and 1500 °C. In the case of 20 vol% LAS compositions, relatively well-densified ceramics (94.4% of the theoretical density) were produced without adding any further sintering additive. The addition of yttria and alumina oxides allowed enhancing the densification level up to 98.2% (20 vol% LAS compositions) or from 62.3% up to 96.7% of the theoretical density in 5 vol% LAS materials. Nevertheless, it was impossible to full consolidate silicon nitride/LAS composite ceramics at temperatures lower than the temperature at which β-eucryptite melts, even by using SPS technology. Moreover, because of the relatively low temperatures involved in SPS, the α to β-Si₃N₄ transformation was avoided, resulting in microstructures composed of fine equiaxed α-Si₃N₄ grains (<200 nm) and of a glassy phase. Even if the effect of having a very large negative thermal expansion material was lost during the sintering step (because of the β-eucryptite melting), ceramics containing only 20 vol% of LAS-based phase exhibited very interesting values as regards of mechanical properties (strength, hardness, toughness, and Young's modulus), thermal conductivity and thermal expansion coefficient. We discuss in this work why we are so interested in developing dense silicon nitride/LAS ceramics sintered without any further additive addition, even though β-eucryptite is melted during the process and the transformation to the β phase is avoided.     

A novel statistical generative model dedicated to face recognition

In this paper, a novel statistical generative model to describe a face is presented, and is applied to the face authentication task. Classical generative models used so far in face recognition, such as Gaussian Mixture Models (GMMs) and Hidden Markov Models (HMMs) for instance, are making strong assumptions on the observations derived from a face image. Indeed, such models usually assume that local observations are independent, which is obviously not the case in a face. The presented model hence proposes to encode relationships between salient facial features by using a static Bayesian Network. Since robustness against imprecisely located faces is of great concern in a real-world scenario, authentication results are presented using automatically localised faces. Experiments conducted on the XM2VTS and the BANCA databases showed that the proposed approach is suitable for this task, since it reaches state-of-the-art results. We compare our model to baseline appearance-based systems (Eigenfaces and Fisherfaces) but also to classical generative models, namely GMM, HMM and pseudo-2DHMM.     

Temperature stability of a pure metakaolin based K-geopolymer: Part 2. Variations in the mesoporous network and its rehydration stability

The thermal behavior of a model MK-based K-geopolymer was investigated between room temperature and 1400°C in order to evaluate its potentiality for high-temperature applications. The purpose of our study was to monitor the behavior of a geopolymer during a temperature rise in order to better understand its variations with respect to temperature. The works from the present paper focus only changes in the porous network; it follows a first part devoted to variations in the mineral matrix. The results obtained here show that the geopolymer material preserves its porous integrity up to 800°C, while maintaining the reversibility of water exchanges corresponding to about 25 weight percent. Together with the results of part 1, the findings of this study allow us to affirm that geopolymer materials are only very little affected by temperatures up to 800°C, or even 900°C (keeping its mesoporous amorphous structure).     

Reconstruction of the Grenfell Tower fire – Part 4: Contribution to the understanding of fire propagation and behaviour during horizontal fire spread

The tragic events at Grenfell Tower in 2017, involving a combustible façade system, have raised concerns regarding the fire risk that these systems pose. In this series of articles, so far published, fire development inside the initial apartment has been investigated using an appropriate computational fluid dynamics (CFD) model. Several scenarios including different fire sources and ventilation conditions were addressed. Fire propagation through the window to the external façade and to higher apartments was modelled. This model was validated by comparing the numerical results with the visual observations reported in the Grenfell Inquiry. A CFD model of the complete east face of the Grenfell Tower was then created. This paper details CFD modelling of the complete Grenfell Tower façade during the late horizontal phase of fire spread. As the physics of lateral flame spread is different from that for upward flame spread, it is important to assess the validity of the model, thus far developed, for this configuration. Fire propagation over the whole façade is modelled and compared with observations from the real disaster. This provides a better understanding of its fire behaviour and of the contribution of architectural details and their impact on fire spread.