Reproducing gravity through spinor fields

We show how to mimic gravitational processes described by general relativity using self-interacting spinor fields as the basic fundamental entities to describe gravity.     

Assisted history matching in the presence of frequent well intervention using generalize travel time inversion

In this paper we propose an efficient and novel technique that handles production discontinuities through a resampling of the production data, eliminating high frequency production details in a transformed domain. The technique also reduces non-monotonic behavior and results in a response more suitable for the GTTI based misfit calculations. Our proposed approach has been applied to an offshore turbidite reservoir with extensive well intervention resulting in highly detailed production responses. The static model contains more than three-hundred-thousand cells, complex sand depositional distribution combined with fault structures, four pairs of injector-producers, deviated producing wells and more than 8 years of production history. Previous history matching attempts using traditional approaches had difficulties matching production response at the individual well level. With our proposed modifications to the GTTI approach, a significant improvement was obtained on the well level match quality. Most importantly, by visualizing the streamlines and the dynamic adjustment of flow paths during history matching, we could easily identify the areas of inconsistency between the geologic model and the production data. The calibrated geologic model and streamline trajectories provided important insight about communication within sand channels, differences in flow paths and barriers that have not been included in the previous geologic and seismic interpretation.     

STL-free design and manufacturing paradigm for high-precision powder bed fusion

High-precision powder bed fusion (PBF), together with highly complex geometries necessitate a much more scalable representation of the geometry and an efficient computational pipeline. This paper presents a new digital design and manufacturing paradigm to solve the scalability and efficiency challenges by using the concept of STL-free workflow. It seamlessly integrates implicit solid modelling for design and direct slicing for manufacturing without any intermediate steps related to STL meshes. The presented paradigm has been validated by two case studies involving complex geometries filled with multiscale triply periodic minimal surfaces (TPMS), which are fabricated by PBF with laser beam size 25 µm.     

FAME Production and Fatty Acid Profiles from Moist Chlorella sp. and Nannochloropsis oculata Biomass

In the present study, we investigated the production of fatty acid methyl esters (FAME) from moist Chlorella sp. and Nannochloropsis oculata biomass using a hydrolysis–esterification process. Additionally, we evaluated for the first time the fatty acid profile before and after this process. Hydrolysis of the lipid fraction was performed on a moist biomass in the presence of differing amounts of an acid catalyst in both 50 and 100 % w/w water relative to the biomass. The esterification of the crude extracts of the free fatty acids (FFA) was then investigated. The experiments show that in the presence of 50 % w/w water relative to the biomass, the hydrolysis–esterification process results in higher FFA and FAME yields. The analysis of the fatty ester profiles did not reveal any degradation of the FFA from the microalgae biomass under the hydrolysis–esterification conditions. The results were compared with both extraction–transesterification and direct transesterification processes using dry biomass. The extraction–transesterification and hydrolysis–esterification processes resulted in similar FAME yields and similar profiles of the fatty esters from dry and moist biomass materials, respectively.     

Soft X‐ray Ptychographic Imaging and Morphological Quantification of Calcium Silicate Hydrates (C–S–H)

Morphological details of calcium silicate hydrate (C–S–H) stemming from the hydration process of Portland cement (PC) phases are crucial for understanding the PC‐based systems but are still only partially known. Here we introduce the first soft X‐ray ptychographic imaging of tricalcium silicate (C₃S) hydration products. The results are compared using both scanning transmission X‐ray and electron transmission microscopy data. The evidence shows that ptychography is a powerful method to visualize the details of outer and inner product C–S–H of fully hydrated C₃S, which have fibrillar and an interglobular structure with average void sizes of 20 nm, respectively. The high‐resolution ptychrography image enables us to perform morphological quantification of C–S–H, and, for the first time, to possibly distinguish the contributions of inner and outer product C–S–H to the small angle scattering of cement paste. The results indicate that the outer product C–S–H is mainly responsible for the q^?3 regime, whereas the inner product C–S–H transitions to a q^?2 regime. Various hypotheses are discussed to explain these regimes.     

Changes in Coupled Vibration Frequencies and Modes of Wall-Cavity Systems Induced by Stiffness Variation in the Structure

Problems of fluid structure interactions are governed by a set of fundamental parameters. This work aims at showing through simple examples the changes in natural vibration frequencies and mode shapes for wall-cavity systems when the structural rigidity is modified. Numerical results are constructed using ANSYS software with triangular finite elements for both the fluid （2D acoustic elements） and the solid （plane stress） domains. These former results are compared to proposed analytical expressions, showing an alternative benchmark tool for the analyst. Very rigid wall structures imply in frequencies and mode shapes almost identical to those achieved for an acoustic cavity with Neumann boundary condition at the interface. In this case, the wall behaves as rigid and fluid-structure system mode shapes are similar to those achieved for the uncoupled reservoir case.     

Stresses Analysis on a Rail Part

The EFVM （Vitoria Minas Railroad） is one of the main railways in Brazil. It transports freight trains of ore, 220 wagons each. These wagons have 2 boogies of 2 axles each and 32 metric tons on metre gauge. Elastic strains were measured on a special part of this railway due to these trains. The main load to evaluate stresses and strains was a G 16 Locomotive, a C-C kind from Vale, a Brazilian Company. The measurements were obtained by dynamic deflectometer installed on a main line of this railway, near Ipatinga, a city from Minas Gerais, one of Brazil states. This track was equipped to obtain stresses under an equal repeated static load A simulation of the stresses was made under critical strain by Ferrovia 1.0 software. It was also made an evaluation of unequal results from neighbor sleepers taking in comparison two equipped parts of this railway, one with compacted ballast and no compaction to the other. The results were strain limited, avoiding breakage or damage to the studied rails. This work analyses these measurements focusing on the improvement of track quality.     

Troubleshooting in geoelectrical prospecting using real‐coded genetic algorithm with chromosomal extrapolation

This work presents a genetic operator developed from mathematical methods of curve extrapolation applied in solving problems in geoelectrical prospection. This operator will assist the production of fitter individuals in the population of a genetic algorithm in which inherent patterns of the best individuals of each generation are recognized. The proposed operator in conjunction with a real‐coded genetic algorithm is compared to five alternative optimization techniques known and used in the application to problems in geoelectrical prospection. Copyright © 2014 John Wiley & Sons, Ltd.     

A linear programming model for cash flow management in the Brazilian construction industry

A linear programming model has been developed for optimal cash flow management addressing specific cash flow issues related to the construction industry. These include typical financial transactions, possible delays on payments, use of available credit lines, effect of changing interest rates, and budget constraints that often occur in the construction industry. A small size project from the Brazilian construction industry is provided as a case study, aiming at evaluating the potential benefits from using the model. Different changes to the basic structure of the model allow and establish the consistency of the results. Alternative formulations are suggested to deal with uncertainties, longer planning horizons, and multiple subcontractors and suppliers. In addition to the tangible financial earnings derived from the optimization process, the simple structure of the model, as a network flow and corresponding equations, provides much visual insight concerning the relationships between the external inputs and the variables of the problem. Optimal results have yet to be achieved in a real life situation, but a better view of whole cash flow management is provided when using the model.     

Territorial development in the Cape Verde archipelago under the Estado Novo dictatorship (1953–1974)

Despite Portugal's neutrality in the Second World War (1939–1945), the subsequent new world order meant that the Portuguese Government felt obliged to revise its overseas policies. A new regional awareness could be seen in the Six-Year National Development Plans launched by Estado Novo from 1953 until the revolution of 1974. The territory and its strategic potential were emphasized in the context of national policies of overseas urbanization. Interventions in Cape Verde are visible particularly in the First Development Plan, which was based on equipping the province's public facilities. The methodology of intervention involved setting up missions aimed at planning a set of specific public works which were essential to the development of existing settlements. A sharp increase in the development of the territory through the work of specialized brigades took place in the Third Development Plan, when a set of public works on road, hydraulic and electricity networks was undertaken. The planning of infrastructures that was undertaken in these years was essential to the development of the archipelago and the resulting regional and urban land-use planning of the various islands.