Preferred Path Research Articles

Benchmarking conventional and machine learning segmentation techniques for digital rock physics analysis of fractured rocks

Image segmentation remains the most critical step in Digital Rock Physics (DRP) workflows, affecting the analysis of physical rock properties. Conventional segmentation techniques struggle with numerous image artifacts and user bias, which lead to considerable uncertainty. This study evaluates the advantages of using the random forest (RF) algorithm for the segmentation of fractured rocks. The segmentation quality is discussed and compared with two conventional image processing methods (thresholding-based and watershed algorithm) and an encoder–decoder network in the form of convolutional neural networks (CNNs). The segmented images of the RF method were used as the ground truth for CNN training. The images of two fractured rock samples are acquired by X-ray computed tomography scanning (XCT). The skeletonized 3D images are calculated, providing information about the mean mechanical aperture and roughness. The porosity, permeability, flow fields, and preferred flow paths of segmented images are analyzed by the DRP approach. Moreover, the breakthrough curves obtained from tracer injection experiments are used as ground truth to evaluate the segmentation quality of each method. The results show that the conventional methods overestimate the fracture aperture. Both machine learning approaches show promising segmentation results and handle all artifacts and complexities without any prior CT-image filtering. However, the RF implementation has superior inherent advantages over CNN. This method is resource-saving (e.g., quickly trained), does not need an extensive training dataset, and can provide the segmentation uncertainty as a measure for evaluating the segmentation quality. The considerable variation in computed rock properties highlights the importance of choosing an appropriate segmentation method.

Characterization of the CRTM process applicated to a door reinforcement

The automotive industry has benefited to some extent from composites for several decades, especially for non-primary structural applications. Technologies such as GMT, LFT or SMC are used to manufacture interior components, functional parts or body parts, with productivity standards and very competitive prices. But despite these successful applications, their expansion to more structural parts is not possible because of the limited properties of the materials and largely because the current manufacturing processes and facilities are not ready for mass manufacturing. When it is intended to manufacture pieces with high fiber contents and / or large pieces, the increase in fiber content decreases the permeability of the preform, necessitating longer filling times, and generating impregnation problems and high pore contents. In order to solve these drawbacks associated with conventional RTM, different alternatives have been explored: increasing the injection pressure, injecting through multiple entries or reducing the viscosity of the resin among others. One of the most promising is the combination of RTM and compression, called CRTM (Compression RTM). Comparing with conventional RTM, the mold remains partially open in the injection phase, generating a space not occupied by the fibers that exerts a preferred flow path for the resin without having to penetrate the preform. The objective of the project has been to characterize the CRTM process and apply this knowledge in the manufacture of a side door reinforcement.

Finite discrete-element modeling of multifracture propagation in fractured reservoirs

Abstract The topology of induced fractures by hydraulic fracturing is important for well performance in unconventional low-permeability reservoirs. Natural fractures are a common feature in geological formations and are preferred failure paths during hydraulic fracturing. Therefore, the interaction of hydraulic fractures and natural fractures is fundamental to the fracture growth in fractured reservoirs. Field observations of induced fracture systems show modeling fracture complexity to be needed for improving completion design and interpreting stimulated reservoir volume. In this study, a finite discrete-element model is presented to investigate multifracture propagation in fractured reservoirs. The numerical model captures the fracture complexity including branched, stranded, and kinked fractures, as well as offset crossing of natural fractures. The results show biased fracture growth in the fractured reservoir, which demonstrates the impacts of rock heterogeneity on multifracture propagation. This work also emphasizes the control of fluid partition at the wellbore and among the intersecting fractures. Fluid partition at the wellbore is found to be a major challenge to the completion design of tight cluster spacing, which has been shown to improve production in recent years.

Alcohol oxidation with high efficiency and selectivity by nickel phosphide phases

Ni12P5nanoparticles are used for electro-oxidation of various alcohols through a preferred reaction path, by O–H activation, that supresses futher oxidation to CO2and produces valuable chemicals.

Elucidating the role of hydrogen species originating from water vapor in the oxidation mechanism of cerium

The oxidation process of cerium in air (by oxygen and water vapor) is elucidated by combining structural and compositional analyses of the oxide with time. The oxide contains a high content of hydrogen, present mainly as hydroxyls in the upper part and hydride ions at the interface with the metal. The high content of hydroxyls on the oxide's surface leads to the formation of a thin hydroxide layer (Ce(OH)3) and to an increased oxidation rate. The observed anisotropy in oxidation rate (111) < (220) < (200) is consistent with the efficiency for H2O splitting and to the preferred paths for OH- diffusion.

University in an oil-dependent state economy: The future of Khuzestan higher education

Purpose of the study: The understanding of the complex world and the ability to imagine the futures is the basis for planning and decision-making. Therefore, in this research, the possible future of university in an Iranian oil-dependent economy is studied, and, the best direction for higher education in Khuzestan province is explored. — Methodology: A formative scenario writing research method is used in the current study. The participants were recruited from among Iranian higher education experts purposefully; a series of in-depth interviews including personal and focus group interviews have also been conducted to reach saturation. —Main findings: The results of the present research showed that two main factors affect Khuzestan higher education: dependency on the state economy and increasingly growing social expectation from the university. Khuzestan universities have better select one of these orientations: Conservative University, Enabler University, Adaptive University, and Developmental University. According to the findings of the study, developmental orientation is the preferred scenario for Khuzestan higher education. — Applications of this study: It is argued that the developmental university is the preferred scenario for the future of higher education in Khuzestan Province and a proposal suggests its actualization. — Novelty/originality of this study: The applied scenario-based innovative research attempts to reveal the socio-economic role of universities in societies having State-Economy such as Iran, shows all the possible main paths, and finally determines the preferred path for a specific period of time. The current probe can be directly used to lead higher education policymakers of the province and be indirectly employed to help individuals adopt general orientations in higher education, as well as students and researchers who are interested in higher education studies, especially in the field of Higher Education (HE) public policymaking. Finally identified and explained the developmental university that is compatible with Khuzestan higher education situations is another novelty of this research.&#x0D; Received: 29 March 2021Accepted: 21 June 2021

Informational interviews help undergraduate students at the mid-point of non-vocational STEM degrees confirm their career aspirations

Higher education institutions are expected to produce career-ready graduates who are equipped for the challenges of the 21st century. Employability experts argue that this can be achieved by integrating career development learning (CDL) into the curriculum. The informational interview helps students learn more about a career by interviewing a professional working in a field of interest, and helps students to make decisions regarding their career plans. The aims of the study were to determine students’: 1) preferred career paths and career identity at the midpoint of their non-vocational degree; 2) experiences and perceptions of an informational interview module. An informational interview module was embedded into a second-year human biosciences subject taken by students in undergraduate non-specialist health-related STEM degrees. Students indicated their preferred career, learned about informational interviews, and conducted an interview with a professional working in the field they wished to enter. After the interview, students completed reflection activities, responding to open-ended and Likert-scale questions. 91 student reflections were analysed to determine students’ career identity, and their experiences and perceptions of the module. Descriptive statistical analysis was conducted on Likert-scale answers and inductive thematic analysis was conducted on open-ended answers. Students’ career preferences were wide-ranging, with allied health the most popular. Career identity was reasonably well established in this cohort. The student experience was overall positive, and students’ thought the module was useful in supporting their career planning and career development. In conclusion, an informational interview assignment is an effective career development tool for human biosciences students.

Ethyl Lauroyl Arginate, an Inherently Multicomponent Surfactant System.

Ethyl lauroyl arginate (LAE) is an amino acid-based cationic surfactant with low toxicity and antimicrobial activity. It is widely used as a food preservative and component for food packaging. When stored, LAE decomposes by hydrolysis into surface-active components Nα-lauroyl–l-arginine (LAS) or dodecanoic (lauric) acid. There are only a limited number of reports considering the mechanism of surface activity of LAE. Thus, we analysed the surface tension isotherm of LAE with analytical standard purity in relation to LAE after prolonged storage. We used quantum mechanical density functional theory (DFT) computations to determine the preferred hydrolysis path and discuss the possibility of forming highly surface-active heterodimers, LAE-dodecanoate anion, or LAE-LAS. Applying molecular dynamics simulations, we determined the stability of those dimers linked by electrostatic interactions and hydrogen bonds. We used the adsorption model of surfactant mixtures to successfully describe the experimental surface tension isotherms. The real part surface dilational modulus determined by the oscillation drop method follows a diffusional transport mechanism. However, the nonlinear response of the surface tension could be observed for LAE concentration close to and above Critical Micelle Concentration (CMC). Nonlinearity originates from the presence of micelles and the reorganisation of the interfacial layer.

Frank-van der Merwe growth in bilayer graphene

Frank-van der Merwe growth in bilayer graphene

A revised narrative of the May 18, 1980 Plinian eruption of Mount St. Helens: Changes in the conduit and magma supply

This compilation re-visits the May 18, 1980 Plinian eruption sequence of Mount St. Helens and correlates new and existing observations and measurements for a revised narrative of when and how eruption behavior changes occurred. It presents new observations of vesicle textures in white pumice and analyses of lithic materials that are correlated with observed eruption behavior. These and the compositional and seismic research by others provide constraints to a proposed process of how the conduit system was modified during the Plinian sequence. The eruption sequence is sub-divided into 3 periods interpreted to represent changes in magma supply and transport as a result of conduit changes. Based on observed pumice textures and composition, the microlite-free, white pumice in the earliest Plinian tephra is interpreted to have been emplaced in a poorly-interconnected, conduit system on or about May 16. The Morning period began with the landslide and lateral blast and initial conduit decompression. The early Plinian column then discharged conduit-resident, white pumice through an effective conduit of ≥20 m radius that produced small, irregular tephra clasts with abundant, small tubular vesicles. Small pyroclastic flows observed about 1010 h started the Transition period and the discharge of small batches of magma from the magma reservoir. Increasingly larger pumice clasts and large, coalesced vesicle textures are attributed to the increased ascent path from the magma reservoir and increased, average ascent rates that increased the rates and extent of bubble growth and coalescence. The eruption intensity that occurred at 1215 h is attributed to an increased magma supply through a modestly, improved conduit. The Afternoon period started at 1300 h as the vertical, eruption column dissipated. Episodic pyroclastic flows from collapsed fountains increased in volume until climax, as a preferred path in the complex, lower conduit was established. Lithic fragments comprise about 40% of deposits of the Pumice Plain and about 70% of the glass was lost as very-fine ash during emplacement. It is proposed that syn-eruptive conduit modification incrementally consolidated adjacent dikes and fractures, improved local interconnections among conduit segments, and removed the lithic debris, so that the conduit configuration was simplified and the effective conduit radius enlarged to ≥43 m during the Climactic phase. The Climactic phase after 1500 h resulted from full conduit interconnection, and magma supply and transport from deeper parts of the reservoir.

Integrating rock physics, PP-PS joint inversion and time-shifts to improve quantitative interpretation of time-lapse fluid and pressure changes

In this study, we show how to overcome the challenges of reliably estimating subtle 4D elastic property changes from seismic acquisitions just one year apart. We show that this is possible thanks to: 1) availability of highly repeatable seismic data and permanent reservoir monitoring (PRM); 2) the methodology for building 4D rock physics models that quantify 4D uncertainties related to seismic repeatability, 3) improving the quality of time-lapse estimates, especially at impedance S, due to the application of the 4D PP-PS joint inversion. This article summarizes the work of quantitative 4D interpretation by reporting how to build 4D rock physics models, how to estimate 4D elastic attributes (joint inversion of PP-PS data) and how the integrated interpretation of these results is performed. To validate the 4D interpretation, the results were compared to the production data from the injector and producer wells and to the outputs of the flow simulator. The integrated analysis shows how injection and production operations affect the reservoir properties, indicating preferred paths for water flow, the role of faults in reservoir hydraulic connectivity, regions where hydrocarbon production caused depletion, areas pressurized by water injection, and even the effect of the salinity contrast between the injection water and the brine. The application of this methodology allows updates to the simulation model that will affect future decisions.

A cost-minimizing approach to eliminating the primary sources of greenhouse gas emissions at institutions of higher education

PurposeMany institutions of higher education have committed to carbon neutrality. Given this goal, the main economic issue is minimizing cost. As for society as a whole, dominant decarbonization strategies are renewable electricity generation, electrification of end uses and energy efficiency. The purpose of this paper is to describe the optimum combination of strategies.Design/methodology/approachThere are four questions for eliminating the primary institutional greenhouse gas emissions: how much renewable electricity to produce on-site; where and at what price to purchase the balance of renewable electricity required; how to heat and cool buildings without fossil fuels; and how much to invest in energy efficiency. A method is presented to minimize decarbonization costs by equating marginal costs of the alternates.FindingsThe estimated cost of grid-purchased carbon-free energy is the most important benchmark, determining both the optimal level of campus-produced renewable energy and the optimum efficiency investment. In the context of complete decarbonization, greater efficiency investments may be justified than when individual measures are judged only by fossil-fuel savings.Practical implicationsThis paper discusses a theoretically ideal plan and implementation issues such as purchasing carbon-free electricity, calculating marginal costs of conserved energy, nonmarginal cost changes, uncertainty about achieving efficiency targets, and dynamic pricing. The principles described in this study can be used to craft a cost-minimizing decarbonization strategy.Originality/valueWhile previous studies discuss decarbonization strategies, there is little economic guidance on which strategies are optimal, on how to combine strategies to minimize cost or how to identify a preferred path to decarbonization.

PIV measurement of complex flow characteristics in open-cell metal foam replica

Time-resolved 2-D particle image velocimetry was used to study on turbulent flow characteristics inside an open-cell metal foam under the laminar and turbulent inlet conditions. A study on the effect of Reynolds number was conducted with different three channel Reynolds numbers, 1000, 5000 and 10000. Uniform upstream flow is divided by the pore network of metal foam and it is found that there are flow disturbances induced by metal foam structure even at a laminar inlet condition. It is confirmed that there is a similarity of the preferred flow path flows take regardless of Reynolds number.

Evidence of room-temperature ferromagnetism in vertically aligned Bi–Co co-doped ZnO nanowires

We are the first to report Bi–Co co-doped zinc oxide nanowires (ZnO NWs) to investigate theoretically and experimentally the alignment of relative spin and the location of Bi3+ and Co2+ as the primary cause of magnetism. In the present study, we carefully performed theoretical and experimental studies of ZnO NWs prepared by the hydrothermal method and obtained exciting outcomes. The x-ray diffraction findings show that the NWs have a wurtzite crystal structure and high intensity at the (002) peak, indicating that most of the reflection comes from the hexagonal surface of the NWs. This means that the extended NWs are mainly aligned along the c-axis. The field-emission scanning electron microscope results show that, due to its anisotropic crystal existence, the grown NWs have a preferred path along the c-axis in the (001) direction. X-ray photoelectron spectroscopy studies established the presence of both Bi and Co in all the Bi–Co co-doped samples. They also showed that OH− groups exist on the surface of ZnO NWs, and increasing Co content tends to increase the O-deficient region in the ZnO matrix. UV–vis analysis showed a decreased optical band gap upon doping, which is probably due to the sp-d exchange interaction between localized d-electron bands of dopants. Optical studies also suggested that the doping induced an increase in electron concentration. The Raman results indicate that the ZnO NWs contain crystallization with few defects after Bi–Co-doping. From the magnetic studies, it was observed that the ferromagnetism probably originates from the defect-rich regions, i.e. NW surface and Bi and Co sit at ZnO’s substitutional site. In contrast, the core of the NWs remains under the other magnetic state. Our density functional theory studies are in line with the experimental results.

Hydrodynamic study of the oil flow in a protective relay coupled to a power transformer: CFD simulation and experimental validation

The present study aimed at performing a hydrodynamic analysis of the safety device's behavior in a gas relay, using computational fluid dynamics techniques and experimental data validation obtained in a protective relay pilot unit (PRP) using different safety flaps geometries for fault detection within high-power transformers. The proposed methodology was carried out in four stages: (i) development of computational meshes from the three-dimensional geometry of the protective relay and safety flaps; (ii) specification of the physical properties of fluids, boundary conditions, and fluid dynamic models; (iii) obtaining speed profiles, flap angle, oil flow and system pressure difference; and (iv) comparison of simulated and experimental data. The devices installed in the relay showed satisfactory performance for failures caused by the oil volumetric expansion. It was observed that from the flap 10° tilt, the orifice ceases to be the preferred path oil, reducing detection sensitivity of the flow. Using the CFD (computational fluid dynamics) computational tool, it was possible to understand the flow behavior within the relay, allowing to detect quickly and efficiently cases of failure with oil expansion.

A neurobiologically inspired mapping and navigating framework for mobile robots

To improve the cognitive ability of the mobile robot in an unknown environment, this paper proposes an episodic memory based self-organizing learning (EM-SOL) framework for robotic experiences learning, cognitive map building and navigation. This EM-SOL framework uses the spatial cells in the hippocampus and entorhinal cortex to path integrate the robotic kinesthetic cues for dead reckoning, and meanwhile extracts the visual cues to activate state neurons for state recognition. By updating the state neurons network, this framework constructs the robotic episodic memory to store these particular experiences created along the exploration process, and achieves the robotic self-organizing learning. The framework based map building method can optimize the cumulative error by introducing the spatial cells phase reset mechanism, and build an episodic-cognitive map that describes not only the topology relationship but also the cognition relationship between these particular experiences in the environment. Furthermore, a combined topological and metric vector navigation method is presented, which can locate the robot relative to its previous experiences in the memory space, anticipate a preferred global path to the target, and guide the mobile robot to navigate to the target accurately. Finally, the proposed EM-SOL framework based methods are evaluated in both the physical environments and the standard KITTI dataset. The results show that the mobile robot can keep on learning to adapt to the changes in an unknown environment, construct valid episodic memory to store these particular learned experiences, build an episodic-cognitive map and execute the target navigation task with high efficiency and accuracy.

Influence of alternated drying and wetting on the characteristics of soil preferential flow formation in Honghe Arid Valley.

To clarify the effects of alternation of drying and wetting on the formation of soil preferential flow in arid valley, taking the wasteland in the arid valley of Honghe River as the research object, we analyzed the soil preferential flow characteristics before and after the simulation of drying and wetting alternation based on dyeing tracer method, water breakthrough curve, and image processing technology. The results showed that, under the simulated alternation of drying and wetting, the matrix flow occurred in the 0-10 cm soil layer, the dyeing depth reached 35 cm, the horizontal width of the preferred path was only 3-10 cm, and the dyeing area curve fluctuated little. Simulated alternation of drying and wetting led to significant increases in the steady effluent, macropores number, and macroporosity. In the 0-20 cm soil layer, the steady effluent after alternation of drying and wetting was about 0.27 cm3·s-1 higher than that non-alternation of drying and wetting, macropores number in dyeing area was about 1.4 times higher, and the macroporosity was 13.4% higher. The macropores number was positively correlated with stable flow rate. After simulated alternation of drying and wetting, the number of macropores from large to small was 0.6-0.8 mm＞0.8-1.0 mm＞1.0-1.5 mm＞1.5-2.0 mm＞2.0-3.7 mm, while under non-alternation of drying and wetting, it was 0.8-1.0 mm＞0.6-0.8 mm＞1.0-1.5 mm＞2.0-3.7 mm＞1.5-2.0 mm. The macropores number in each pore size range was significantly correlated with the dyeing area ratio. After simulated alternation of drying and wetting, the correlation increased, and the dominant factor affecting the occurrence of preferential flow changed from the macropores number in the pore size range of 1.5-2.0 mm to that of 0.8-1.0 mm. Therefore, the alternation of drying and wetting would affect the characteristics of macropores, which caused the soil to be more prone to preferential flow and with higher magnitude.

Maximizing the synergistic effect of PdAu catalysts on TiO2(1 0 1) for robust CO2 reduction: A DFT study

To provide insight into how to realize maximization of the synergistic effect of supported PdAu catalysts, we have performed first-principles calculations for CO2 reduction over PdAu/TiO2(1 0 1). The results indicate that introducing a secondary metal (Au) to supported Pd catalyst and controlling Au concentration can affect the binding energy of reactants and also alter the dominant reaction pathway. The energetically preferred path for CO2 reduction on Pd8-xAux/TiO2 changes from the formate pathway (referred to as the “CO2 HYD” pathway) (x = 0–3) to the reverse water-gas shift and CO hydrogenation (“RWGS + CO HYD”) pathway (x = 4–6). Notably, the CO2 reduction activity shows a volcano trend as a function of the binding energy of the initial reactant CO2* in the “CO2 HYD” pathway or the adsorption energy difference between CHO* and CO* in the “RWGS + CO HYD” pathway. In addition, there is a component-dependent relationship between the water-promotion-effect and the nanoalloy structure. This work proposes fundamental insights into the effect of nanoalloy composition and water promotion in maximizing the synergy of PdAu catalysts for CO2 reduction, providing facile descriptors for the activity of reaction pathways, and offering important guidance for rational design of supported nanoalloy catalysts.

Response to select comments on the proposed paradigm shifts in running

Background: Six experts in the field of running-related research have critically addressed a proposal to abandon the paradigms of ‘impact force’ and ‘pronation control’ when investigating running shoes, running injury, and running performance. Further, these experts have commented on the suggestion of the new paradigms of ‘muscle tuning’ and the ‘preferred movement path’ that can be used to investigate questions related to running injuries and performance as well running shoe design and comfort. This publication synthesizes and addresses the main criticisms of the experts and describes future directions to further develop the ‘muscle tuning and ‘preferred movement’ paradigms.

Bridging microstructure and crystallography with the micromechanics of cleavage fracture in a lamellar pearlitic steel

The present paper focuses on the microstructure-based cleavage crack propagation in a Charpy impact tested fully pearlitic steel by correlating microstructure and crystallography with the overall fracture behavior. The importance of pearlite lamellae orientation in providing preferred fracture paths is discussed, encompassing the mechanism of interface decohesion and stepwise crack propagation through a mathematical model simulation. While the {100} cleavage cracking is well familiar in pearlitic steels, crack propagation along the {110} crystallographic planes can also prevail in some pearlite colonies or nodules. This is related to suppressing the crack tip dislocation emissions due to restricted slip transferability across the lamellae interfaces. Besides, the strain incompatibility due to large elastic modulus or Schmid factor mismatch across the pearlite nodule boundaries is responsible for triggering internodular cracking in the steel. Connecting the framework of fracture mechanics with the experimental observations, the mechanisms pertaining to different types of tear ridges formed within a pearlite colony are proposed. This certainly illuminates the role of lamellae orientation in the process of crystal bending and shearing at the tear ridges formed within the colonies or at the twist nodule boundaries.