Flow Barriers Research Articles

Microsatellite and mitochondrial markers reveal strong gene flow barriers for Anopheles farauti in the Solomon Archipelago: implications for malaria vector control

Anopheles farauti is the primary malaria vector throughout the coastal regions of the Southwest Pacific. A shift in peak biting time from late to early in the night occurred following widespread indoor residue spraying of dichlorodiphenyltrichloro-ethane (DDT) and has persisted in some island populations despite the intervention ending decades ago. We used mitochondrial cytochrome oxidase I (COI) sequence data and 12 newly developed microsatellite markers to assess the population genetic structure of this malaria vector in the Solomon Archipelago. With geographically distinct differences in peak A. farauti night biting time observed in the Solomon Archipelago, we tested the hypothesis that strong barriers to gene flow exist in this region. Significant and often large fixation index (FST) values were found between different island populations for the mitochondrial and nuclear markers, suggesting highly restricted gene flow between islands. Some discordance in the location and strength of genetic breaks was observed between the mitochondrial and microsatellite markers. Since early night biting A. farauti individuals occur naturally in all populations, the strong gene flow barriers that we have identified in the Solomon Archipelago lend weight to the hypothesis that the shifts in peak biting time from late to early night have appeared independently in these disconnected island populations. For this reason, we suggest that insecticide impregnated bed nets and indoor residue spraying are unlikely to be effective as control tools against A. farauti occurring elsewhere, and if used, will probably result in peak biting time behavioural shifts similar to that observed in the Solomon Islands.

Asthenospheric Pacific‐Atlantic flow barriers and the West Scotia Ridge extinction

AbstractThe Drake Passage is considered a gateway for oceanic and asthenospheric flows since its opening, entailing widespread consequences for climate and plate tectonics, respectively. Both the surface and the 50 km upward continued Bouguer anomaly maps of the Scotia Sea and surrounding areas, based on Gravity Recovery and Climate Experiment gravity satellite data, improve our knowledge of deep lithospheric structures and the asthenosphere. We show that the West Scotia Sea is likely to be underlain by an anomalously low‐density upper mantle. Gravity data are compatible with variable lithospheric thicknesses related to asthenospheric currents. The new data suggest that the development of the Shackleton Fracture Zone since the middle Miocene was probably a main factor that determined the evolution of the eastward Pacific mantle flows and the extinction of the West Scotia Sea oceanic spreading around 6 Ma ago. Deep lithospheric roots are likely to divert asthenospheric currents around them, flowing eastward through Drake Passage.

Genetic diversity of an Azorean endemic and endangered plant species inferred from inter-simple sequence repeat markers.

Knowledge of the levels and distribution of genetic diversity is important for designing conservation strategies for threatened and endangered species so as to guarantee sustainable survival of populations and to preserve their evolutionary potential. Picconia azorica is a valuable Azorean endemic species recently classified as endangered. To contribute with information useful for the establishment of conservation programmes, the genetic variability and differentiation among 230 samples from 11 populations collected in three Azorean islands was accessed with eight inter-simple sequence repeat markers. A total of 64 polymorphic loci were detected. The majority of genetic variability was found within populations and no genetic structure was detected between populations and between islands. Also the coefficient of genetic differentiation and the level of gene flow indicate that geographical distances do not act as barriers for gene flow. In order to ensure the survival of populations in situ and ex situ management practices should be considered, including artificial propagation through the use of plant tissue culture techniques, not only for the restoration of habitat but also for the sustainable use of its valuable wood.

Appraisal of intra-reservoir barriers in the Permo-Triassic successions of the Central Persian Gulf

Owing to their tightness, intra reservoir barriers have the potential to prevent homogenization of reservoir fluids and so cause compartmentalization. Identification of these barriers is an important step during reservoir evaluation. In order to achieve this, three main approaches: i) detailed petrographic and core analysis, ii) petrophysical studies (flow unit concept) and iii) geochemical analysis (strontium residual salt analysis) were applied systematically in the Permo-Triassic carbonate reservoirs (Dalan and Kangan formations) of a supergiant gas reservoir located in the Central Persian Gulf. Integration of these approaches has led to a fullclarification of the intra reservoir barriers. Petrographic examinations revealed the potential stratigraphic barriers to fluids flow created by various depositional/ diagenetic characteristics. Petrophysical data such as poroperm values, pore throat size distribution and scanning electron microscopy (SEM) analysis were used to differentiate the reservoir flow units from non-reservoir rock. According to different trends in 87Sr/86Sr ratios of residual salts, the existence of flow barriers was evaluated and proved. Finally, by integrating these approaches, three intra reservoir barriers were introduced in the studied reservoir interval. These intra reservoir barriers are depositional and diagenetic in nature and are located in stratal positions with sequence stratigraphic significance. The possibility of reservoir compartmentalization was evaluated in the studied wells, and then their existence was predicted at the adjacent fields. As shown in this study, integration of petrographic examinations with flow unit determination in a sequence stratigraphic framework has the potential for recognizing intra reservoir barriers and predicting compartmentalization of the studied Permo-Triassic reservoirs.

INTROGRESSION IN THEDROSOPHILA SUBOBSCURA—D. MADEIRENSISSISTER SPECIES: EVIDENCE OF GENE FLOW IN NUCLEAR GENES DESPITE MITOCHONDRIAL DIFFERENTIATION

Species hybridization, and thus the potential for gene flow, was once viewed as reproductive mistake. However, recent analysis based on large datasets and newly developed models suggest that gene exchange is not as rare as originally suspected. To investigate the history and speciation of the closely related species Drosophila subobscura, D. madeirensis, and D. guanche, we obtained polymorphism and divergence data for 26 regions throughout the genome, including the Y chromosome and mitochondrial DNA. We found that the D. subobscura X/autosome ratio of silent nucleotide diversity is significantly smaller than the 0.75 expected under neutrality. This pattern, if held genomewide, may reflect a faster accumulation of beneficial mutations on the X chromosome than on autosomes. We also detected evidence of gene flow in autosomal regions, while sex chromosomes remain distinct. This is consistent with the large X effect on hybrid male sterility seen in this system and the presence of two X chromosome inversions fixed between species. Overall, our data conform to chromosomal speciation models in which rearrangements are proposed to serve as gene flow barriers. Contrary to other observations in Drosophila, the mitochondrial genome appears resilient to gene flow in the presence of nuclear exchange.

Syntectonic fluid-flow along thrust faults: Example of the South-Pyrenean fold-and-thrust belt

During compressive events, deformation in sedimentary basins is mainly accommodated by thrust faulting and related fold growth. Thrust faults are generally rooted in the basement and may act as conduits or barriers for crustal fluid flow. Most of recent studies suggest that fluid flow through such discontinuities is not apparent and depends on the structural levels of the thrust within the fold-and-thrust belt.In order to constrain the paleofluid flow through the Jaca thrust-sheet-top basin (Paleogene southwest-Pyrenean fold-and-thrust belt) this study compares on different thrust faults located at different structural levels. The microstructures in the different fault zones studied are similar and consist of pervasive cleavage, calcite shear veins (SV1), extension veins (EV1) and late dilatation veins (EV3). In order to constrain the nature and the source of fluids involved in fluid-rock interactions within fault zones, a geochemical approach, based on oxygen and carbon stable isotope and trace element compositions of calcite from different vein generations and host rocks was adopted. The results suggest a high complexity in the paleohydrological behaviors of thrust faults providing evidence for a fluid-flow compartmentalization within the basin. Previous studies in the southern part of the Axial Zone (North of the Jaca basin) indicates a circulation of deep metamorphic water, probably derived from the Paleozoic basement, along fault zones related to the major basement Gavarnie thrust. In contrast, in northern part of the Jaca basin, the Monte Perdido thrust fault is affected by a closed hydrological fluid system involving formation water during its activity. The Jaca and Cotiella thrust faults, in turn, both located more to the south in the basin, are characterized by a composite fluid flow system. Indeed, stable isotope and trace element compositions of the first generations of calcite veins suggest a relatively closed paleohydrological system, whereas the late calcite vein generations, which are probably associated with the late tectonic activity of the basin, support a contribution of both meteoric and marine waters. Based on these results, a schematic fluid-flow model is presented. This model allows visualization of three main fluid flow compartments along a N–S transect.

A pore-level screening study on miscible/immiscible displacements in heterogeneous models

Abstract A comprehensive understanding of the role of reservoir heterogeneities induced by flow barriers and connate water on sweep efficiency of different EOR scenarios is rarely attended in the available literature. In this work, different miscible/immiscible EOR processes were conducted on various one-quarter five-spot glass micromodels incorporating small-scale flow barriers. Microscopic and macroscopic observations revealed the reduction of sweep efficiency, premature breakthrough of displacing fluids, the severity of fingering at displacement front which leaves a large amount of oil behind the flow barriers untouched, and significant increasing trend of oil recovery after breakthrough in the presence of flow barriers. For the range of experiments performed here, the higher oil recovery is attained by polymer, hydrocarbon solvent, surfactant and water flooding. Flow around the shale streaks is strongly influenced by capillary forces during immiscible floods. Shales on the small-scale affect oil recovery by reducing effective permeability and increasing residual oil saturation. The effect of convection is much more profound than diffusion transport mechanism during oil displacements by hydrocarbon solvent in shaly models; as well, pore-level visualizations disclosed that the presence of connate water in solvent injection process improves the recovery efficiency specifically at higher water saturations, but it acts conversely for the case of immiscible floods. The obtained results provide opportunities for possible quantifying the impact of discontinuous impermeable barriers on sweep efficiency, and identifying bypassed oil zones for future infill drilling in heterogeneous heavy oil systems.

Using landscape epidemiological models to understand the distribution of chronic wasting disease in the Midwestern USA

Animal movement across the landscape plays a critical role in the ecology of infectious wildlife diseases. Dispersing animals can spread pathogens between infected areas and naive populations. While tracking free-ranging animals over the geographic scales relevant to landscape-level disease management is challenging, landscape features that influence gene flow among wildlife populations may also influence the contact rates and disease spread between populations. We used spatial diffusion and barriers to white-tailed deer gene flow, identified through landscape genetics, to model the distribution of chronic wasting disease (CWD) in the infected region of southern Wisconsin and northern Illinois, USA. Our generalized linear model showed that risk of CWD infection declined exponentially with distance from current outbreaks, and inclusion of gene flow barriers dramatically improved fit and predictive power of the model. Our results indicate that CWD is spreading across the Midwestern landscape from these two endemic foci, but spread is strongly influenced by highways and rivers that also reduce deer gene flow. We used our model to plot a risk map, providing important information for CWD management by identifying likely routes of disease spread and providing a tool for prioritizing disease monitoring and containment efforts. The current analysis may serve as a framework for modeling future disease risk drawing on genetic information to investigate barriers to spread and extending management and monitoring beyond currently affected regions.

Local differentiation amidst extensive allele sharing in Oryza nivara and O. rufipogon.

Genetic variation patterns within and between species may change along geographic gradients and at different spatial scales. This was revealed by microsatellite data at 29 loci obtained from 119 accessions of three Oryza series Sativae species in Asia Pacific: Oryza nivara Sharma and Shastry, O. rufipogon Griff., and O. meridionalis Ng. Genetic similarities between O. nivara and O. rufipogon across their distribution are evident in the clustering and ordination results and in the large proportion of shared alleles between these taxa. However, local-level species separation is recognized by Bayesian clustering and neighbor-joining analyses. At the regional scale, the two species seem more differentiated in South Asia than in Southeast Asia as revealed by FST analysis. The presence of strong gene flow barriers in smaller spatial units is also suggested in the analysis of molecular variance (AMOVA) results where 64% of the genetic variation is contained among populations (as compared to 26% within populations and 10% among species). Oryza nivara (HE = 0.67) exhibits slightly lower diversity and greater population differentiation than O. rufipogon (HE = 0.70). Bayesian inference identified four, and at a finer structural level eight, genetically distinct population groups that correspond to geographic populations within the three taxa. Oryza meridionalis and the Nepalese O. nivara seemed diverged from all the population groups of the series, whereas the Australasian O. rufipogon appeared distinct from the rest of the species.

The Clinician/Health Educator Team and Counseling for Long-Acting, Reversible Contraception

The popularity of long-acting reversible contraception (LARC) is increasing in the USA, but national surveys show that women at highest risk for unintended pregnancy still face barriers to access. This session will present findings on provider LARC knowledge and practice, and tools and resources for patient counseling on LARC from the University of California, San Francisco and Planned Parenthood National Trial of Contraceptive Acceptability. This cluster randomized trial tested the impact of a clinic-wide training at 40 Planned Parenthood health centers across the US. This study is the first to examine the role of health educators in the provision of LARC. The impact of the clinic-wide training on LARC knowledge and practice, including the use of evidence-based criteria for determining client eligibility will be examined. Also, concordance of knowledge between health educators and clinicians, and how it impacts overall clinic practices will be explored. Finally, the presenters will facilitate an interactive session on skills and tools for counseling that is tailored to the concerns of the audience, including selected tools for overcoming clinic flow, billing and counseling barriers.

Simulating the Chemical Interaction of Injected CO2 and Carbonic Acid

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper IPTC 16703, ’Simulation of the Chemical Interaction of Injected CO2 and Carbonic Acid Based on Laboratory Tests in 3D Coupled-Geomechanical Modeling,’ by Rahim Masoudi, SPE, and Mohd Azran Abd Jalil, Petronas; Chee Phuat Tan, SPE, David Press, SPE, John Keller, and Leo Anis, SPE, Schlumberger; and Nasir Darman and Mohamad Othman, SPE, Petronas, prepared for the 2013 International Petroleum Technology Conference, Beijing, 26-28 March. The paper has not been peer reviewed. The M4-field reservoir is approximately 2000 m below sea level in a water depth of approximately 120 m. A carbon dioxide (CO2) geological-storage study was carried out to determine the feasibility of injecting and storing CO2 in the depleted M4 carbonate gas reservoir. The study used 3D coupled-geomechanical modeling. The water level in the reservoir has risen close to the caprock, which implies a strong aquifer. Laboratory tests were carried out on core samples before and after injecting CO2-saturated brine solution, and the results were used to determine material-strength and elastic-property degradation caused by acid/carbonate interaction. Introduction Controlling the trapping of CO2 in the subsurface is fundamental for safe geological storage of CO2. Rock formations can be impervious enough to act as flow barriers to CO2 over geological periods of time. Delineating such a seal, safeguarding its integrity under operational conditions, and verifying its isolation effectiveness are key objectives in achieving a successful CO2-storage project. During CO2 injection, the increasing fluid pressure, temperature variation, and chemical reactions between the gas and rock will inherently affect the stress state of the reservoir and its surroundings. Also, the rock mechanical properties may be altered by exposure to CO2 or by pressure and stress changes. Further, rock mechanical properties, pore pressure, in-situ stresses, and the stress evolution under injection conditions control reactivation of a fault and, therefore, risk of fault-seal breach. The effect of the resulting stress and pressure change, the associated caprock deformation, and the fault-seal integrity must be assessed to manage containment performance and leakage-related risks properly. To address these issues, a good understanding of the flow dynamics, in-situ stresses, pore pressure, and rock mechanical properties in the field is necessary. The fracture initiation, propagation, and containment in the injection zones, and caprock and fault-seal integrity, are related to the in-situ stresses and the coupled pressure/thermal behavior while injecting. Rock-Property Tests A comprehensive program of mechanical- and petrophysical-property tests was conducted on selected overburden-shale and reservoir-limestone cores from Well A-2. The tests evaluated potential interaction between injected CO2 and the reservoir rock and caprock that could result in a change in mechanical properties of the rock materials and affect CO2 storage and containment. Shale samples from two core depths and limestone samples from three core depths were tested. The study consisted of comprehensive evaluation of near-identical sets of samples from each core depth. One set of samples was tested without being treated with CO2, while the other set of samples was tested after CO2 injection to simulate reservoir-injection conditions. A standardized CO2-injection procedure was used in an effort to quantify the potential effect that CO2 injection has on shale and limestone properties under controlled test conditions.

Landscape heterogeneity predicts gene flow in a widespread polymorphic bumble bee, Bombus bifarius (Hymenoptera: Apidae)

Bombus bifarius is a widespread bumble bee that occurs in montane regions of western North America. This species has several major color pattern polymorphisms and shows evidence of genetic structuring among regional populations, and the taxonomic status of regional populations has repeatedly been debated. We test whether observed structure is evidence for discrete gene flow barriers that might indicate isolation or instead reflects clinal variation associated with spatially limited dispersal in a complex landscape. We first consider color pattern variation and identify geographical patterns of B. bifarius color variation using cluster analysis. We then use climate data and a comprehensive set of B. bifarius natural history records with an existing genetic data set to model the distribution of environmentally suitable habitat in western North America and predict pathways of potential gene flow using circuit theory. Resistance distances among populations that incorporate environmental suitability information predict patterns of genetic structure much better than geographic distance or Bayesian clustering alone. Results suggest that there may not be barriers to gene flow warranting further taxonomic considerations, but rather that the arrangement of suitable habitat at broad scales limits dispersal sufficiently to explain observed levels of population differentiation in B. bifarius.

A systematic study of the sharp-switching Z2-FET device: From mechanism to modeling and compact memory applications

This paper presents a systematic study of a sharp-switching device built in fully-depleted silicon-on-insulator (FD-SOI) that we have called Z2-FET, as it features zero subthreshold swing (<1mV/decade of current) and zero impact ionization. The Z2-FET is a compact device with a single front gate that experimentally demonstrates a current ION/IOFF ratio >108 at low supply voltage, as well as gate-controlled hysteresis. The operating principle of the sharp switching involves the positive feedback between carrier flow and gate-controlled injection barriers, as confirmed by TCAD simulations. We discuss the impact of bias and device dimensions on the experimental performance and simulate the Z2-FET’s ultimate scaling capability to <50nm channel length. We present a simplified compact model of the Z2-FET. With good reliability and relative insusceptibility to temperature variation, the envisioned applications of the Z2-FET include compact, high-speed one transistor DRAM (1T-DRAM), one-transistor SRAM, fast logic and electrostatic discharge (ESD) protection circuits.

Effect of small scale flow barriers heterogeneities and connate water on displacement efficiency of polymer floods to heavy oil reservoirs

AbstractThis work concerns a fundamental understanding of how heterogeneities induced by flow barriers and connate water affect the displacement efficiency of polymer floods, which has rarely been studied in the available literature. Here, a series of water/polymer injection experiments to heavy oil performed on five‐spot glass micromodels containing randomly distributed shale structures is presented. It has been found that macroscopic efficiency of polymer flooding majorly depends on flow barriers distribution/configuration; shale content and geometrical characteristics; presence of connate water and wettability of medium. Microscopic pictures revealed that the main parts of connate water were trapped in some pores/throats near and especially behind the shale streaks; also, presence of connate water causes a reduction of sweep efficiency due to premature breakthrough of displacing fluid in an oil‐wet media. In absence of connate water, polymer solution could linger and stick to the pore walls to delay the time for a polymer to channel to the production site. Results of this work disclose requirements for a detailed geologic study of barrier size and distribution for successful design of EOR processes in heterogeneous reservoirs.

Genetic diversity of natural Miscanthus sinensis populations in China revealed by ISSR markers

Abstract Miscanthus sinensis is a typical perennial C4 grass in Asia. In the present study, ISSR markers were used to evaluate the genetic variation within and among grass populations that were sampled from the Zhejiang and Guangdong Provinces of China. Based on nine ISSR primers, 206 clear and reproducible DNA fragments were generated. Relatively low levels of genetic diversity were determined among the populations. The coefficient of genetic differentiation among the populations was 0.52, which indicates that 52.3% of the total molecular variance exists among the populations. Such a high level of divergence present among the populations might be caused by the complex topography and variable climatic conditions present in the two provinces. AMOVA revealed that the majority of the genetic variation was within the populations (50.6%). The application of a novel method, which combines geographical coordinates and genetic differentiation to detect barriers for gene flow, allowed us to identify two zones of lowered gene flow.

First Application of Progressing Cavity Pumps for Appraisal Well Testing in the Ugandan Albertine Graben Basin

Summary Over 28 production well tests and two interference tests have been conducted in the Albertine Graben basin in Uganda since the first oil discovery in 2006. The Uganda crude is moderately viscous, and low-gas/oil ratio (GOR), and later discoveries were mostly in shallow lower-energy systems. In addition, Uganda crude has relatively high pour points and wax appearance temperatures (WATs), which result in flow-assurance challenges during production testing operations. Production challenges brought about by the low energy scenario are offset by high formation permeability (mostly in the multi-Darcy range). Field X was discovered in 2008 by Well X-1, and subsequently appraised by several wells. Zone 1 of Well X-1 was production tested under natural flow without a rig. Although hydrocarbons were brought to surface successfully during the testing operation, the maximum flow rate achieved was approximately 262 BOPD, and a stable flow rate could not be sustained. Fluid-segregation effects distorted the early-time data. In addition, flow-assurance challenges prevented acquisition of late-time response from the pressure buildup (PBU). Therefore, important dynamic information, particularly in regard to flow barriers, was not obtained. A change in completion philosophy was proposed after detailed analysis of the test results. Well X-1 was retested with a new completion design incorporating real-time surface-readout (SRO) pressure and temperature monitoring capability, a hydraulically controlled inflow control valve (ICV), a progressing cavity pump (PCP), and a surface-controlled electrical heat trace system. High-quality well-test data was acquired, and the real-time data was used extensively throughout operations to optimize flow and buildup periods and well operating envelopes. Several challenges were faced during the first completion run, leading to the use of the contingent insert PCP system to retest Zone 1. This paper highlights the first application of a PCP completion in Uganda and describes the challenges faced during the completion and well-testing operation. The experience from Well X-1 has demonstrated that high-quality exploration and appraisal well-test data can be acquired using a PCP completion. Similar well-completion designs will be used in Uganda for appraisal of other discoveries.

Population genetic structure of Picea engelmannii, P. glauca and their previously unrecognized hybrids in the central Rocky Mountains

Areas of geographic overlap between potentially hybridizing species provide the opportunity to study interspecific gene flow and reproductive barriers. Here we identified hybrids between Picea engelmannii and P. glauca by their genetic composition at 17 microsatellite markers, and determined the broad-scale geographic distribution of hybrids in the central Rocky Mountains of North America, a geographic region where hybrids and isolation between species had not previously been studied. Parameter estimates from admixture models revealed considerable variation in ancestry within and among collection sites, suggesting that within this area of geographic overlap, the interaction of the two species varies extensively. The results document a previously unrecognized patchy distribution of hybrids between P. engelmannii and P. glauca, including locations where hybrids were not known or expected to exist. Further, the ancestry of many hybrids was consistent with multiple generations of hybridization, with probable directional backcrossing to P. engelmannii, suggesting a relatively porous species boundary. The identification and characterization of hybridization between these spruce in this region raises the question of what factors maintain barriers to gene flow in these long-lived forest trees. The current research lays the groundwork for future study of the ecological and evolutionary contexts of their hybridization, as well as of differential introgression and permeability of species boundaries.

Modelling of CO2 Injection in Fluvial Sedimentary Heterogeneous Reservoirs to Assess the Impact of Geological Heterogeneities on CO2 Storage Capacity and Performance

The integration of sedimentary heterogeneity in flow simulations is still a challenging issue in reservoir engineering modelling. Yet in the CCS context, the discussion on how the heterogeneities may impact the flow performances is at the beginning. Fluvial reservoirs consist of complex heterogeneous sedimentary bodies with varying connectivity, controlled by the sedimentary history of the system. The main difficulty is to handle two different scales when evaluating the storage capacity performance of such reservoirs: (i) large scale of the pressure footprint (∼10km) and (ii) small scale of the sedimentary heterogeneity (∼m). This induces the generation of reservoir grids containing several 100 000 of gridblocks making the dynamic flow simulation difficult to handle. In addition to that, the high level of uncertainty requires the generation of several models to cover a large spectrum of equi-probable solution. The present work focuses on fluvial reservoir performances using a stochastic algorithm to reproduce deterministically realistic architectural models with high resolution heterogeneities. Each geological model is split into two identical architectural models that differ in their sedimentary fill. One considers the reservoir bodies (fluvial belts) as homogeneous stacked point bar sand bodies (1st order heterogeneity, Model B), while the second type contains also flow barriers (shale oxbow lakes; 2nd order heterogeneity, Model A). To perform the CO2 injection two codes were used: TOUGH2-MP (integrated finite volume approach with massive parallel implementation) and 3DSL (streamline black oil simulator on a single processor). Two sets of 50 realizations were assessed (Models A and B). The streamline simulations enable quick ranking of dynamic capacity estimate at the scale of the geological model while only eight models could be conducted in a reasonable CPU time framework with TOUGH2-MP. This is explained by the high detailed characterisation of the fluid properties coupled with the flow which lowers substantially the speed of calculations.The study reveals that heterogeneities affect the storage capacity as well as the injectivity of the well. For a reservoir formation with a typical size of 23km x 25 km x 60m, the capacities vary between 2.5 and 11Mt. The presence of oxbow lakes induces a loss of capacity that varies between 1.2Mt (23%) and 1Mt (12%) after 10 years, and 30 years, respectively.

Enhanced polymer filling and uniform shrinkage of polymer and mold in a hot embossing process

AbstractLow filling efficiency and large thermal stress are two important problems that limit the wide use of hot embossing especially in fabricating high aspect ratio patterns. Two types of flow barriers, the first being an accessorial slot on the mold (SFB), the other was a block on the hot embossing machine (BFB), were designed to enhance polymer filling and their performances were simulated with the finite element method. The numerical simulation results show that two kinds of flow barriers can also accelerate the polymer filling speed and improve filling efficiency. The BFB has a better promoting effect and can be easily used as a quasi close‐die embossing process. The shrinkage of the polymer and mold is made uniform with a designed polymer grip holder to minimize the thermal stress. The polymer was clipped at a temperature in a cooling step and its deformation was fixed; thus, the shrinkage of the polymer can be equal to the mold at a special temperature. An improved hot embossing machine was designed and the hot embossing process was modified to satisfy these requirements. At last successful fabrication of the light guide plate verified the improvements. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Lagrangian Coherent Structures for Design Analysis of Revolving Doors.

Room air flow and air exchange are important aspects for the design of energy-efficient buildings. As a result, simulations are increasingly used prior to construction to achieve an energy-efficient design. We present a visual analysis of air flow generated at building entrances, which uses a combination of revolving doors and air curtains. The resulting flow pattern is challenging because of two interacting flow patterns: On the one hand, the revolving door acts as a pump, on the other hand, the air curtain creates a layer of uniformly moving warm air between the interior of the building and the revolving door. Lagrangian coherent structures (LCS), which by definition are flow barriers, are the method of choice for visualizing the separation and recirculation behavior of warm and cold air flow. The extraction of LCS is based on the finite-time Lyapunov exponent (FTLE) and makes use of a ridge definition which is consistent with the concept of weak LCS. Both FTLE computation and ridge extraction are done in a robust and efficient way by making use of the fast Fourier transform for computing scale-space derivatives.