CSimMDMV: A parallel program for stochastic characterization of multi-dimensional, multi-variant, and multi-scale distribution of heterogeneous reservoir rock properties from well log data

We present CSimMDMV, a software package to simulate two- and three-dimensional, multi-variant heterogeneous reservoir models from well logs at different characteristic scales. Based on multi-variant conditional stochastic simulation, this software is able to parameterize multi-dimensional heterogeneities and to construct heterogeneous reservoir models with multiple rock properties. The models match the well logs at borehole locations, simulate heterogeneities at the level of detail provided by well logging data elsewhere in the model space, and simultaneously honor the correlations present in various rock properties. It provides a versatile environment in which a variety of geophysical experiments can be performed. This includes the estimation of petrophysical properties and the study of geophysical response to the heterogeneities. This paper describes the theoretical basis of the approach and provides the details of the parallel implementation on a Linux cluster. A case study on the assessment of natural gas hydrate amount in Northwest Territories, Canada is provided. We show that the combination of rock physics theory with multiple realizations of three-dimensional and three-variant (3D-3V) gas hydrate reservoir petrophysical models enable us to estimate the average amount of gas hydrate and associated uncertainties using Monte Carlo method.     

The epistemology of conceptual clustering: KBG,an implementation

This paper analyzes differences between a numeric and symbolic approach to inductive inference. It shows the importance of existing structures in the acquisition of further knowledge, including statistical confirmation. We present a new way of looking at Hempel's paradox, in which both existing structures and statistical confirmation play a role in order to decrease the harm it does to learning. We point out some of the most important structures, and we illustrate how uncertainty does blur but does not destroy these structures. We conclude that pure symbolic as well as pure statistical learning is not realistic, but the integration of the two points of view is the key to future progress, but it is far from trivial. Our system KBG is a first-order logic conceptual clustering system; thus it builds knowledge structures out of unrelated examples. We describe the choices done in KBG in order to build these structures, using both numeric and symbolic types of knowledge. Our argument gives us firm grounds to contradict Carnap's view that induction is nothing but uncertain deduction, and to propose a refinement to Popper's purely deductive view of the growth of science. In our view, progressive organization of knowledge plays an essential role in the growth of new (inductive) scientific theories, that will be confirmed later, quite in the Popperian way.     

Static and Dynamic Program Compilation by Interpreter Specialization

Interpretation and run-time compilation techniques are increasingly important because they can support heterogeneous architectures, evolving programming languages, and dynamically-loaded code. Interpretation is simple to implement, but yields poor performance. Run-time compilation yields better performance, but is costly to implement. One way to preserve simplicity but obtain good performance is to apply program specialization to an interpreter in order to generate an efficient implementation of the program automatically. Such specialization can be carried out at both compile time and run time.Recent advances in program-specialization technology have significantly improved the performance of specialized interpreters. This paper presents and assesses experiments applying program specialization to both bytecode and structured-language interpreters. The results show that for some general-purpose bytecode languages, specialization of an interpreter can yield speedups of up to a factor of four, while specializing certain structured-language interpreters can yield performance comparable to that of an implementation in a general-purpose language, compiled using an optimizing compiler.     

Balancing the transverse cutting force during inclined milling and effect on tool wear: application to Ti6Al4V

The present article studies the effect on cutter wear of balancing transverse cutting forces during inclined milling applied to a titanium alloy (Ti6Al4V). Indeed, this method is advantageous as it helps reduce vibrations as also the amplitude of such forces thanks to balancing. These observations provide the means to enhance cutting conditions and thus boost productivity when roughing. The method was first validated on Ti6Al4V titanium alloy. A model was then proposed to estimate the maximum axial cutting force at angular positions 0 and p. A wear test was then conducted and notching, flaking and flank types of wear were observed as being most representative. Roughness measurements were made throughout the wear test as also measurements of cutting forces with a new cutter and the worn cutter to provide a comparison. The cutting forces remained acceptable and the roughness values measured remained below the criteria generally retained for roughing. The improvements obtained in terms of extended tool life when using this method were extremely significant since under the same cutting conditions flat milling gave a lifetime of 2.03 min while when machining with balancing of the transverse cutting forces this was extended to 23.6 min.     

Study of the early growth and branching of Streptomyces tendae by means of an image processing system

A method is described for directly observing submerged growth of streptomycetes, which can be easily adapted for investigations of filamentously growing fungi. The use of an image processing system allowed a fast and accurate calculation of important morphological parameters. Most of the images can be analysed on-line. Some results are presented for early growth and branching of Streptomyces tendae. It seems that mechanisms for growth of streptomycetes were the same for both solid and liquid media.     

Three‐dimensional numerical simulation of upflow bubbling fluidized bed in opaque tube under high flux solar heating

Solid particles can be used as a heat transfer medium in concentrated solar power plants to operate at higher temperature and achieve higher heat conversion efficiency than using the current solar heat transfer fluids that only work below 600°C. Among various particle circulation concepts, the dense particle suspension (DPS) flow in tubes, also called upflow bubbling fluidized bed (UBFB), was studied in the frame of the CSP2 FP7 European project. The DPS capacity to extract heat from a tube absorber exposed to concentrated solar radiation was demonstrated and the first values of the tube wall‐to‐DPS heat transfer coefficient were measured. A stable outlet temperature of 750°C was reached with a metallic tube, and a particle reflux in the near tube wall region was evidenced. In this article, the UBFB behavior is studied using the multiphase flow code NEPTUNE_CFD. Hydrodynamics of SiC Geldart A‐type particles and heat transfer imposed by a thermal flux at the wall are coupled in two‐dimensional unsteady numerical simulations. The convective/diffusive heat transfer between the gas and dispersed phase, and the inter‐particle radiative transfer (Rosseland approximation) are accounted for. Simulations and experiments are compared here and the temperature influence on the DPS flow is analyzed. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3857–3867, 2018     

A Stress‐Free and Textured GaP Template on Silicon for Solar Water Splitting

This work shows that a large‐scale textured GaP template monolithically integrated on Si can be developed by using surface energy engineering, for water‐splitting applications. The stability of (114)A facets is first shown, based on scanning tunneling microscopy images, transmission electron microscopy, and atomic force microscopy. These observations are then discussed in terms of thermodynamics through density functional theory calculations. A stress‐free nanopatterned surface is obtained by molecular beam epitaxy, composed of a regular array of GaP (114)A facets over a 2 in. vicinal Si substrate. The advantages of such textured (114)A GaP/Si template in terms of surface gain, band lineups, and ohmic contacts for water‐splitting applications are finally discussed.     

Aromatic Polyketide GTRI‐02 is a Previously Unidentified Product of the act Gene Cluster in Streptomyces coelicolor A3(2)

The biosynthesis of aromatic polyketides derived from type II polyketide synthases (PKSs) is complex, and it is not uncommon that highly similar gene clusters give rise to diverse structural architectures. The act biosynthetic gene cluster (BGC) of the model actinomycete Streptomyces coelicolor A3(2) is an archetypal type II PKS. Here we show that the act BGC also specifies the aromatic polyketide GTRI‐02 ( 1 ) and propose a mechanism for the biogenesis of its 3,4‐dihydronaphthalen‐1(2H)‐one backbone. Polyketide 1 was also produced by Streptomyces sp. MBT76 after activation of the act‐like qin gene cluster by overexpression of the pathway‐specific activator. Mining of this strain also identified dehydroxy‐GTRI‐02 ( 2 ), which most likely originated from dehydration of 1 during the isolation process. This work shows that even extensively studied model gene clusters such as act of S. coelicolor can still produce new chemistry, offering new perspectives for drug discovery.     

A Comparative Study of Single-Phase Modulated AC Choppers

With the increased availability of power MOSFET's and GTO's, a new generation of simple choppers for small and medium ac loads is foreseen. These new power semiconductors ease the use of forced commutation to improve the supply power factor even with highly reactive loads. Asymmetrically-and symmetrically modulated ac choppers designed to operate with reactive loads are described. The ability of the asymmetric chopper to hold a unity power displacement factor for a large range of reactive loads presents interest for induction machine controllers. On the other hand, the supply current produced by the symmetrical chopper has a less objectionable harmonic content than the asymmetrical chopper over a large range of operating conditions. Both choppers are compared to the common ac phase controller, with or without freewheeling switch. Experimental results confirm the analytical analysis. The practical limits of operation for the new choppers are also discussed.     

Alleviation of a transient stability crisis using shunt braking resistors and series capacitors

As a result of a severe disturbance, a bulk electric power system may be perturbed into an emergency state condition, whereby transient stability is not maintained and machine synchronous operation is lost. A generic methodology is presented that uses physical control means to alleviate such a transient stability crisis. Series braking capacitors and shunt braking resistors are the primary control means for such an event because of their speed of operation. The paper presents a simple control model formulated in an observation decoupled Thévenin equilibrium frame as a control space. This approach requires only locally available measurements. The minimum angle optimal aiming strategy is used to decide on necessary control action, which is then implementable through direct and inverse influence mappings presented for the two control means considered. Experimental results are also included to indicate the practical usefulness of these techniques.