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Imperfect determination of petroleum system processes coincidence, entrapment and charge timing, along with reservoir heterogeneity can considerably cause high risks throughout exploration and development phases of petroleum. Therefore, a complete subsurface visualization of the petroleum system nature, elements and processes, is badly required. To this end, we corroborated, in this study, static reservoir modeling with petroleum system analysis workflows, to better characterize the Cenomanian fluvio-marine reservoir, sandstones of Bahariya Formation, at Bed-2 Field, Abu Gharadig basin (Western Desert, Egypt). We used dataset of 2D seismic profiles and well logs of eight wells. The geometry and property of the reservoir were acquired performing static reservoir geocellular modeling approach. The geohistory, timing of charge, migration pathways, and accumulation sites were identified performing 1D and 2D basin modeling approaches. Combining both approaches was aimed at identifying new petroleum prospect areas, and estimating the hydrocarbon volumes, that are the need for such poorly-defined petroleum systems area. As indicated by the constructed, robust, reservoir and 1D-2D basin models, an additional hydrocarbon prospect, to the north central part of Bed-2 Field, is proposed to be drilled during the further oilfield development phases of the area. This prospect has all features that adequately lead to reliable inferences regarding the ultimate petroleum potential of the area.

Spatial management of fishing effort can be used to avoid catching undesirable size classes for target species, and improve yield-per-recruit for the exploited stock. Adaptive closure management has been proposed as a means to more effectively utilise spatial management, however these management provisions often lack quantitative evaluation which constrains the information available to inform decisions. We demonstrate the use of a spatially and size structured population dynamics model to evaluate the potential impact of spatial management on a multijurisdictional fishery for a highly migratory species (eastern king prawn, Penaeus [Melicertus] plebejus). Under current conditions in the fishery, the overall effect of closures on harvest was estimated to be comparatively minor, regardless of assumptions about how effort or fisher behavior are affected by spatial management. Alternative assumptions about the movement patterns of eastern king prawn had little influence on the impact of closures on overall harvest. However, when effort was increased to historic levels similar to those observed when the closures were implemented, a much greater impact on overall harvest was observed. The approach taken and simulation outcomes are discussed in the context of spatial management for both eastern king prawn, and penaeid fisheries more broadly.

The hydraulic fracturing technology has been widely utilized to extract tight resources. Hydraulic fracturing involves rock failures, complex fracture generation, proppant transport and fracture closure. All these behaviors affect the productivity of fractured wells. In this work, the advances and challenges in hydraulic fracturing development of tight reservoirs are summarized from following aspects: the hydraulic fracture propagation, the proppant transport and distribution in hydraulic fractures, the calculation of hydraulic fracture conductivity, and productivity and/or pressure analysis model of multi-stages fractured horizontal wells. Current fracture propagation simulation methods generate only limited propagation paths and cannot truly reflect the complexity of the propagation. The current proppant migration and distribution research is mainly focused on indoor experimental studies of proppant migration in a single fracture or branched fracture, and simulation studies on proppant migration and distribution in a small-scale single slab fracture. Whereas fractures formed after hydraulic fracturing in tight reservoirs are generally complicated. There is a lack of models for calculating complex fracture conductivity that take into consideration the effect of proppant placement and proppant distribution in fractures, fracture surface roughness and dissolution, diffusion, deposition, elastic embedding, and creep caused by stress. The productivity models of fractured horizontal wells are mostly conducted based on the original reservoir fluid saturation and pressure distribution. Most of the studies are focused only on one aspect of the fracturing process. Predications of well performance after fracturing based on these studies are often inconsistent with actual field data. The paper also discusses the future research directions of fracturing in tight reservoirs and the results may be used to promote the development of tight reservoirs.

The void closure model is urgently needed for the subsequent hot forming process of additive manufacturing (AM) products. The influence of temperature, Lode parameter, and hydrostatic integration (Gm) on void closure was studied by representative volume element (RVE) simulations. The results show that Gm and the Lode parameter significantly influence void closure, and the temperature effect is related to material properties. A new model accounting for Gm and Lode parameter in evaluating void closure was developed using linear regression with an average error of 2.1% in comparison to RVE simulations. X-ray computed tomography (CT) was carried out at different high reductions for the AM cylinder's hot forging experiments. The new and stress-triaxiality-based (STB) models were integrated into the ABAQUS and compared with the CT measurements. Results indicate that the model is more precise than the STB model, suggesting that the model can be appropriately applied to forecast void closure during the hot forging process for AM products.

Grouting is a typical HM (hydro-mechanical) coupling process between slurry and rock and widely used in underground engineering to reinforce the strength of fractured rock mass. In present work, based on numerical manifold method (NMM), an NMM-HM grouting model is proposed to investigate slurry flowing and analyze grouting efficiency. In this NMM-HM grouting model, the slurry flows in fractures and grouting pressure can cause fracture aperture variation and fracture propagation. Then, two numerical examples for central embedded crack and hydraulic fracturing are adopted to validate the presented model. Furthermore, grouting simulations are conducted on a multi-crack and a roadway with fracture networks. Results show that Grouting pressure in fractures can increase fracture aperture, which is beneficial for grouting efficiency. However, fluid pressure could also cause closure of neighboring fractures or even fracture propagation and failure of rock mass, which will weaken grouting effectiveness. Therefore, the coupled HM impacts on grouting efficiency and grouting pressure should be seriously considered and optimized to achieve the expected grouting performance in practice.

All products labeled as sterile are required to be free of microbial contamination throughout their shelf life (obligatory critical quality attribute). Container closure integrity (CCI) needs to be addressed with a holistic life cycle strategy comprising adequate primary packaging components selection and the assessment of critical unit operations and critical process parameters (CPPs) according to quality by design (QbD) principles. The helium leak method is currently the most sensitive CCI test method and preferably used for the initial container closure system (CCS) qualification and characterization studies. Currently, two different measuring principles are used in the pharmaceutical industry, and no data is available in the public domain for typical method performance parameters such as accuracy, precision, intermediate-precision, and limit of quantification of the method. Furthermore, the performance of different types and sizes of artificial leaks as well as certified helium leak standards have not yet been characterized across different test laboratories. In this multicompany study, we shared 17 artificially prepared leak samples using the most common types of artificial leaks in relevant nominal size ranges that are commercially available or can be easily prepared in a laboratory. Each participating company generated results according to their in-house methods, applying their established test parameters as the aim of the study was not to create a standard for helium leak measurements, but to compare real-world performance between different laboratories. Consequently, this study is not an interlaboratory study using the same test method across laboratories.

Snapping shrimps close their special shaped claw to generate a cavitating water jet with high speed, and the pressure pulse can be generated by cavitating bubble bursting. The cavitating jet is produced by its pincers, with the characteristic of high energy focusing. Therefore, for the cavitation jet, it is of great significance to explore the law of cavitation and the focusing principle, which can inspire us to investigate the cavitation effects and develop the bionic cavitation device. In this paper, a bioinspired snapping-claw apparatus with ideal cavitation effect was obtained after a series of optimization designs. And a hypothesis on the principle of cavitation generated by the bioinspired apparatus was proposed. The general process is as follows: on the basis of the existing CT scan and geometric surface reconstruction of the actual shrimp, a 3D bionic model that preserves the basic geometric features was established. By solving the dynamic equation of the bubble, the critical conditions of cavitation, temperature and maximum pressure at the moment of bubble bursting are obtained. To explore the characteristics of pincers that have influences on energy focusing mechanism and cavitation effects, on the basis of the results obtained through CFD simulation, the optimized bionic structure and the influencing principle was obtained through continuous improvement of several groups of simulation. The typical parts of bionic structures that influence submerged cavitation jets were summarized as well. Furthermore, a series of corresponding control groups were set for the sizes of these typical parts of structures respectively, and the influences of these typical parts with different sizes on the cavitation effect were explored. Finally, combined with the surface morphology of real pincers of snapping shrimps, the qualitative hypothesis of cavitation mechanism during the closure of the snapper-claw was raised based on the simulation results finished.

This paper presents numerical studies on modeling of bubble induced turbulence at two significantly different scales. On the scale of a bubble swarm, direct numerical simulations are performed with a geometric volume-of-fluid method and the budget equation of liquid phase turbulence kinetic energy is analyzed. By a priori testing of models for the interfacial term in this equation, suitable closure relations are identified. On the scale of an industrial bubble column, simulations with a two-fluid model are performed with water and cumene as liquid phases under elevated pressures. Turbulence is taken into account by a mixture k – e model, considering two closure relations for the interfacial term identified from the DNS. For both liquids, an influence of the model for the interfacial term on turbulence kinetic energy and gas holdup is found, which is, however, small at elevated pressures. Numerical results for local and overall gas holdup are in reasonable agreement with measurements reported for this industrial pilot-scale bubble column. For the overall gas holdup, an empirical correlation from literature is identified which predicts the present numerical results reasonably well.

After the completion of multi-stage fracturing operation, the fluid pressure in artificial fracture network continues to decrease, resulting in the closure of fracture and the variation of local induced stress field. This process can also lead to the variation of fracture propagation pattern in the subsequent fracturing stages. To better guide fracturing design, the time effect of stress field was researched. A numerical method was used to solve the induced stress around a propped fracture, and analyze the influence of formation properties and treatment parameters on its change. Then, the characteristics of stress field with different closure times and its influence on subsequent fracture were investigated. Finally, the evolution of the stress field in two stimulated wells was analyzed using the instantaneous shut-in pressure. The results show that the original horizontal stress difference, fluid pressure in fracture, fracture length, fracture angle, and amount of proppant have significant effects on the variation of induced stress field. The stress field of formation with undeveloped natural fractures decreases quickly with the rapid closure of hydraulic fractures due to the rapid drop in fluid pressure, but the stress field remains relatively constant after the fracture is fully propped. For formation with developed low angle natural fractures, the stimulated stage promotes subsequent fracture propagation and improves fracturing efficiency. The fluid pressure declined slowly and is non-uniformly distributed during the closure of the complex fracture network. Therefore, the magnitude and scope of the induced stress vary unevenly with the closure time, and there is a reasonable treatment time to form complex fractures during hydraulic fracturing. This study provides new insights into fracturing operation.

Closures are a language feature supported by many mainstream languages, combining the ability to package up references to code blocks with the possibility of capturing state from the environment of the closure's declaration. Closures are powerful, but complicate understanding and formal reasoning, especially when closure invocations may mutate objects reachable from the captured state or from closure arguments. This paper presents a novel technique for the modular specification and verification of closure-manipulating code in Rust. Our technique combines Rust's type system guarantees and novel specification features to enable formal verification of rich functional properties. It encodes higher-order concerns into a first-order logic, which enables automation via SMT solvers. Our technique is implemented as an extension of the deductive verifier Prusti, with which we have successfully verified many common idioms of closure usage., Proceedings of the ACM on Programming Languages, 5 (OOPSLA), ISSN:2475-1421

In 2017 and 2019, injection testing was carried out in three zones in a vertical well in granite at the Frontier Observatory for Research in Geothermal Energy site near Milford, Utah, USA. In several injection cycles, flowback was implemented rather than shut-in. The goal was to explore an alternative to prolonged shut-in periods for inferring closure stress, formation compressibility, and formation permeability (permeability thickness product). The flowback procedures involved a cyclic flowback/shut-in, while pressure decreased. The flowback data are presented, and analyses are shown. The inferred closure stress(es) from flowback analyses are lower than for equivalent injection cycles that were strictly shut-in. Relatively high formation compressibility obtained from the flowback analyses indicates an extensive, fractured system. This study also includes numerical simulation of the flowback events. The numerical model shows that the rebound pressure is not necessarily the lower bound of the minimum principal stress. The signature of stiffness change can be identified as the process when the depletion mainly transitions from hydraulic fracture to natural fractures from numerical analysis. Overall, flowback potentially has advantages over shut-in because of the reduced time to closure.

We examine whether the local press is an effective monitor of corporate misconduct. Specifically, we study the effects of local newspaper closures on violations by local facilities of publicly listed firms. After a local newspaper closure, local facilities increase violations by 1.1% and penalties by 15.2%, indicating that the closures reduce firm monitoring by the press. This effect is not driven by the underlying economic conditions, the underlying local fraud environment, or the underlying firm conditions. Taken together, our findings indicate that local newspapers are an important monitor of firms’ misconduct.

Taking Shanyang tunnel of Dali to Ruili (DaRui) railway as background, the construction technology of micro bench cut method for weak rock tunnel with high in-situ stress is established by combining the full-fgenius tunnelling method and bench cut method. For weak rock tunnel with large deformation, corresponding construction control points and technical characteristics are discussed. The following results are achieved. (1) The horizontal convergence deformation of Shanyang tunnel is larger than that of the subsidence displacement of the vault. Feet-lock bolt, reinforced grouting of arch foot surrounding rock, and expand support measures for arch foot are equipped to increase the stability and resistance of the supporting steel frame. (2) The narrow working surface of a single-line tunnel can be effectively utilized and the rapid construction of tunnel is also realized. (3) The construction technology can realize the rapid closure of the initial support into a ring, ensure the tunnel safety of the IV and V grade surrounding rock, reduce the construction cost, and improve the construction efficiency. The construction methods and techniques proposed in the article can provide reference for similar projects.

Starting with L as an enriched cl-premonoid, in this paper, we explore some categorical connections between L-valued topological groups and Kent convergence groups, where it is shown that every L-valued topological group determines a well-known Kent convergence group, and conversely, every Kent convergence group induces an L-valued topological group. Considering an L-valued subgroup of a group, we show that the category of L-valued groups, L-GRP has initial structure. Furthermore, we consider a category L-CLS of L-valued closure spaces, obtaining its relation with L-valued Moore closure, and provide examples in relation to L-valued subgroups that produce Moore collection. Here we look at a category of L-valued closure groups, L-CLGRP proving that it is a topological category. Finally, we obtain a relationship between L-GRP and L-TransTOLGRP, the category of L-transitive tolerance groups besides adding some properties of L-valued closures of L-valued subgroups on L-valued topological groups.

Made available in DSpace on 2022-04-28T19:42:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-09-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Mining enterprises are, in essence, landscape modifiers and sources of long-term environmental degradation. The development of activities within the mines requires a complex logistical system for better functioning. It is common to have gas stations in the vicinity of mining areas as a support for supplying vehicles and machines. Inadequate operation and the absence of monitoring, as well as a planned closure of the activities of these stations, may impose risks of contamination of the geological environment. This work presents the efficiency of using electrical resistivity tomography (ERT) to map aged hydrocarbon in the subsurface in a former gas station area in a uranium mine. The presence and flow of hydrocarbons in the geological environment are also investigated through structural analysis of the area integrated with the geophysical results. The ERT results show a clear connection between the low-resistivity anomalies contained in the subsoil and the presence of the rock mass. Of particular interest, the ERT results made it possible to model the fractures contained in the subsoil and that condition a certain flow orientation between porous and fractured systems. The integrated analysis of geophysical and structural surveys proved to be essential in cases of fractured aquifer contamination. Department of Geology (DG) Geosciences and Exact Sciences Institute (IGCE) Universidade Estadual Paulista (UNESP), 24-A Avenue, 1515, Bela Vista Environment and Water Resources Department São Paulo College of Technology (FATEC) Geology Department Center for Natural and Health Sciences Espírito Santo Federal University (UFES) Post-graduation Program in Geosciences and Environmental Science Geosciences and Exact Sciences Institute (IGCE) Universidade Estadual Paulista (UNESP) Department of Geology (DG) Geosciences and Exact Sciences Institute (IGCE) Universidade Estadual Paulista (UNESP), 24-A Avenue, 1515, Bela Vista Post-graduation Program in Geosciences and Environmental Science Geosciences and Exact Sciences Institute (IGCE) Universidade Estadual Paulista (UNESP) FAPESP: 2018/14565-3

Objectives To investigate the relationship between the closure of "anchor businesses" - manufacturing plants and distribution centers employing >1,000 workers and the daily, county-level COVID-19 rate between March 1 and May 31, 2020. Methods We conducted a comparative, interrupted time series analysis of publicly available county-level data. Our main variable of interest was closure, indicating whether one or more of the anchor businesses within the county experienced a full or partial a closure of at least 22 days (main analysis) or at least one day (sensitivity analyses). Results Closure of an anchor business was associated with 142 fewer positive COVID-19 tests per 100,000 population over a 40-day period. Even short-term and partial closures were associated with reduced spread. Conclusions Temporary closure of anchor businesses appears to have slowed, but not completely contained, the spread of COVID-19.

Sludge recirculation mixing in anaerobic digesters is essential for the stable operation of the digestion process. While often neglected, the configuration of the sludge inlet has a substantial influence on the efficiency of the mixing process. The fluid is either injected directly into the enclosed fluid domain or splashes onto the free surface of the slurry flow. In this paper, the aim was to investigate the effect of the inlet configuration by means of computational fluid dynamics—using ANSYS Fluent. Single-phase and multi-phase models are applied for a submerged and splashing inlet, respectively. To reduce the high computational demand, we also develop surrogate single-phase models for the splashing inlet. The digester mixing is analyzed by comparing velocity contours, velocity profiles, mixing time and dead volume. The non-Newtonian characteristics of the sludge is considered, and a $$k-\varepsilon $$ k - ε model is employed for obtaining turbulence closure. Our method is validated by means of a previous study on the same geometry. Applying a submerged inlet configuration, the resulting dead volume in the tank is estimated around 80 times lower than for the case of a splashing inlet. Additionally, by emulating the multi-phase model for splashing inlet configurations with a single-phase one, the simulation clock time reduced to 15%.

This paper explores the variations of the temperatures of a black high-density polyethylene (HDPE) geomembrane (GMB) liner in a municipal solid waste landfill through the lens of a field case study. The geomembrane temperature was monitored from the start of the construction phase to the closure phase, a span of 7 years. Solar radiation had a significant effect on the temperature variations of the geomembrane while exposed to the atmosphere. The more significant impact was on the geomembrane on the side slope of the cell, where temperatures were much higher than on the cell floor. A white geotextile cushion did not insulate the geomembrane from solar radiation, which still experienced elevated temperatures. However, the placement of the drainage layer reduced the impact of solar radiation on the GMB and insulated it. The daily temperature variation of the geomembrane covered with a white geotextile varied from 12 °C to 38 °C at floor level but dropped to 20 °C after the placement of the drainage layer. Along the side slope, without the drainage layer, the daily temperature variation of the GMB fluctuated between 5 and 59 °C and dropped to 23 °C after the installation of the drainage layer.

Currently, a great deal of controversy exists regarding the real forces generated in drawbeads during sheet metal forming processes. The present work focuses on the analysis of the uplift force. First, a detailed literature review is carried out to analyse previous experimental procedures used to measure uplift forces. It is found that previous setups do not perfectly replicate the real geometry of industrial drawbeads. In order to obtain reliable forces, an experimental drawbead tester capable of adequately replicating industrial drawbeads is developed. Later, a variety of steels ranging from mild steels to 3rd-generation ultra-high-strength steels are tested and reliable uplift and also restraining force values are obtained. The main purpose of the work is to share with the research community reliable experimental data that allows precise evaluation of the accuracy of current drawbead models and that supports the generation of new numerical and equivalent drawbead models. In parallel to the experimental procedure, a step forward in the understanding of the drawbead closing phenomena is also achieved through a 2D numerical model. The main purpose of the model is to identify the variables that greatly affect uplift force. Going beyond previous studies, in which some variables were analysed, the present work covers, in a holistic manner, the impact that material properties, the geometry of drawbeads and contact behaviour between sheet and drawbead have on the uplift force. It is determined that surprisingly minor geometrical deviations in the drawbead nominal geometry have a large impact on the uplift force.

A technique for setting boundary conditions on solid surfaces based on the method of near-wall functions is presented. The technique is based on solving the Reynolds-averaged Navier-Stokes equations with the Spalart-Allmaras (SA) closure model in the boundary layer approximation. The obtained solution is used to formulate flow boundary conditions that compensate the insufficient mesh resolution of the boundary layers. For a simplified system of equations, discretization is performed and a solution algorithm is constructed. A parallel software implementation of the method is carried out in a finite-volume computational code. Based on the test cases, which are canonical turbulent flows, a series of calculations are carried out to demonstrate the capabilities of the developed technique. Recommendations and limitations related to the practical application of the proposed technique are developed.

We perform a comparison study of different subgrid scale closures in large-eddy simulations (LES) of the non-stationary boundary layer dynamics during the evening transition. In particular, we consider LES models supplemented with the dynamic procedure, which allows the variation of subgrid closure parameters (Smagorinsky coefficient and subgrid Prandtl number) in space and time and a recently proposed model based on the minimum dissipation approach. As a reference we present the results for the classical Smagorinsky subgrid model. We address the grid sensitivity of results and computational performance of LES models on different CPU architectures, including Intel Xeon, AMD EPYC, and ARM-based Kunpeng processors.

Accurate simulation of meteorological variables is a prerequisite for numerous downstream applications such as air quality modeling and weather forecasting. Weather Research and Forecasting (WRF) model is widely utilized to simulate various prognostic meteorological variables across multiple spatial scales. The suitability of the WRF-v3.9 model in simulation of surface meteorological variables and vertical thermodynamic profile is tested with available in situ surface and radiosonde observations collected from the locations representing rural, semi-urban, and urban environments of the central Indian region. Nested domains with 12 and 4 km grid spacing having 28 vertical layers are set up during the fair weather days of January and March 2018. The model sensitivity is tested by varying two non-local (Yonsei University, YSU and Asymmetric Convective Model, ACM2) and one local (Mellor-Yamada Eta, MY-E) closure Planetary Boundary Layer (PBL) schemes. Results indicate that no particular PBL scheme simulates best for all meteorological variables at different land uses. Overall, thermodynamic variables (temperature and relative humidity) are more accurately simulated than the dynamic variables (wind speed and direction). YSU and MY-E schemes have relatively better accuracy in simulating surface temperature in rural and semi-urban locations, while ACM2 performed better in the urban location. MY-E is relatively better in simulating relative humidity and wind speed in rural and semi-urban locations, while it poorly performed in the urban location. The vertical thermodynamic profile is perfectly correlated with radiosonde observations over the urban location during January and with a reasonably good fit during March. The study provides a comprehensive evaluation of boundary-layer meteorological variables simulated by the WRF model in Central India.

The safe construction of transverse channel was the premise to ensure the smooth construction of the shallow-buried excavated metro station. Based on the construction of the transverse channel of Shikui Road station of Dalian Metro Line 5, the surface settlement, the stress of the support structure and the removal length of the primary lining were analyzed by using the field monitoring data and numerical simulation. The results showed that the excavation of shaft caused disturbance to the rock at the beginning of the transverse channel, and it was necessary to adopt advanced grouting bolt to reinforce the surrounding rock before the excavation of transverse channel, so as to make up for the stratum loss. The biggest disturbance to the ground surface and rock mass was the construction of the first and second pilot tunnels on the left side of the transverse channel, and the surface settlement caused by this stage accounted for 58% of the total settlement. The area affected by the construction of the transverse channel was within 4 times the diameter of the pilot tunnel from the center line of the transverse channel. The rapid closure of the primary lining at the top of the transverse channel could effectively reduce the disturbance to rock mass and ground surface caused by the excavation of large section of the lower pilot tunnels. Based on the numerical simulation results, the removal length of the primary lining was determined to be 12 m, and its rationality was verified effectively in the actual construction. The research results could provide reference for the design and construction of similar projects.

The study of artificial ground freezing temperature field is a necessary means to grasp the development status of frozen walls. The effective freezing radius of the frozen soil column is usually calculated by the measured data of the temperature measuring hole, and then the intersecting time of the frozen walls is predicted. The location of the temperature measuring holes is random and the number of designs is small. The weak points in the blind area of the monitoring cannot be grasped in time, resulting in the consequence that local observation replaces the overall temperature field of the frozen walls. In order to accurately judge the closed condition of the frozen wall, the longitudinal temperature measurement was carried out for the frozen apparatuses. According to the heat conduction of the frozen soil column, a mathematical model for calculating the transient temperature rise of a single hole frozen soil column after short-term cooling stop is established. It used the Maple mathematical calculation software to digitize and graph the formula, which reveals the relationship between the temperature distribution of the frozen soil column and the radius and time. According to the relationship between the above parameters, the minimum frozen column radius is determined to locate the weak position of the frozen wall. Finally, taking the Xipang air shaft of Dongpang Mine in China as an engineering case, theoretical calculation and analysis of the longitudinal temperature data of all freezing apparatuses are carried out. The results show that the 18# ~ 22# and 8 # ~ 10 # freezing holes are the weak points of the frozen wall, and the groundwater flow scours the frozen wall, resulting in a “gap” at these positions. The study effectively solved the problem that the abnormal groundwater flow affected the closure of the freezing wall, and provided a theoretical basis for the treatment of water inrush accident of the frozen wall.

In this work we propose a method for mini-frac analysis via the direct numerical modeling for permeability and closure stress determination. The idea is to adjust the model parameters to match the simulated and field pressure curves by the virtue of the optimization algorithm to automatize the routine. To this end, the Planar 3D hydraulic fracturing model is improved to take into account the wellbore storage, fracture initiation and pumping through a finite perforation interval. The reservoir mechanical behavior is based on Biot’s equations naturally coupled with the mass conservation law and force balance in the fracture and wellbore. This model is capable to describe all the pressure curve features from the fracture initiation up to the after closure filtration. The optimization workflow is based on Levenberg–Marquardt algorithm with Jacobi matrix calculated via a direct differentiation method. The numerical stability and performance of the inverse problem solution is verified. The pressure curve sensitivity analysis is conducted and the impact of the parameters’ uncertainties on the pressure change is calculated. The proposed method is applied to a field case and compared with classical mini-frac methods. We demonstrate that the wellbore storage impact governs the pressure increase during the fracture initiation and prevents the steep pressure decline after closure. We also show that the shortening of the perforation length generates additional pressure support at the end of and after the fracture closure. The recovered permeability and closure stress appears to be stable in presence of uncertainties in Young’s modulus and Biot’s coefficient.

In this study, flowback-assisted minifrac tests were conducted in low-permeability shale and salt formations to measure the in situ stress. An injection/flowback testing protocol was implemented in each test to achieve accuracy and efficiency. Accurate and efficient injection/flowback testing is very important, given the impermeable nature of these formations and the need to complete each test as quickly as possible. Each flowback cycle yields a distinct and repeatable fracture closure signature, simplifying the interpretation of the fracture closure pressure. The objective of this paper is to share our field experience and to present a numerical analysis of the flowback test pressure responses, fracture closure behaviors, and fracture closure diagnostic methods. Examples from open-hole and cased-hole minifrac tests are used to demonstrate site operation procedures. Then, two numerical models are presented for simulating the fracture closure behavior during a flowback test. Field evidence is provided to demonstrate that the fracture closure pressures from the flowback tests are identical to those from tests without flowback. The fracture closure diagnostic methods for flowback tests are discussed, and it is found that the G-function diagnostic method yields a distinct fracture closure signal during the flowback tests. This study is intended to provide additional insights regarding flowback tests by sharing our successes, experience, and knowledge, thereby benefiting the industry.

A synchronous optimization model for rehabilitation of existing two-way two-lane (TWTL) highways is proposed in this paper considering geometric modification and existing pavement rehabilitation. The rehabilitation process of existing roadways is categorized into geometric design modifications and pavement repairs. These two types of modification apply separately in roadway life-cycle because of the difference in nature of these repairs, which impose an extra cost and time of closure to road users and owners. This paper aims to address the modification of existing highways by a new approach linking the existing pavement condition and geometric configuration changes of the developed roadway to provide the optimum vertical alignment. The proposed procedure depends on various parameters of existing pavement condition, cross-section configuration, traffic volume and composition, and current alignment composure. In the first step, all these dependencies are explained and quantified with separate cost models. For each solution, the overall cost is calculated with a life-cycle cost analysis approach. Finally, a particle swarm optimization (PSO) based model is developed to find the optimum solution. The developed model was applied in two case studies with good and adverse geometric conditions. The results show that there is a critical condition in the roadway segments which have all these conditions: (1) the grade is more than three percent, (2) the grade is following with reverse grade, and (3) decommissioning of the asphalt concrete (or extended to lower layers) exist. The optimum solution in these critical conditions suggests the modification of the geometric configuration before the pavement rehabilitation in order to reduce the overall cost. In the absence of these conditions, the optimum alignment is more analogous with the existing alignment of the highway.

Stability is the main problem in underground excavations that can result in rock-related accidents or closure of mines. This is often controlled by the geological condition of the rockmass and the in situ stress field where excavation is being carried out. Over the years, conventional support systems such as bolts, shotcrete and mesh have been the standard support systems used in difficult ground conditions to maintain stability of underground openings. The novel Thin Spray Liner (TSL) is a technology with an improvement in terms of support capabilities for difficult geological conditions. This technology is predicted to replace conventional support systems, as it offers a significant yielding capacity that is better than that of the traditional techniques of controlling strata. The performance of the TSL lies between that of shotcrete and wire mesh. The TSL has numerous advantages regarding rock reinforcement such as rapid curing period, fast application, high tensile strength, high adhesion properties that prevent movement of rock keyblocks, improved cycle times, reduction in material-handling compared to shotcrete, and a significant ability to penetrate joints. These advantages increase the allowance for mechanisation and improvement of safety in excavations. Despite various benefits of TSLs, there are shortcomings which make end-users to be sceptical about the technology. This study provides a detailed review of the mechanism, properties, composition and types, as well as the general and mining applications of TSLs. It also describes the challenges faced by the mining industry and other end-users in accepting the technology as a solution for stability issues in underground openings. In addition, some insightful suggestions are made as recommendations for future work on the development of suitable, effective and efficient thin surface rock support technology within limitations/constraints.

Accurate prediction of the wall temperature downstream of the trailing-edge slot is crucial to designing turbine blades that can withstand the harsh aerothermal environment in a modern gas turbine. Because of their computational efficiency, industry relies on low-fidelity tools like RANS for momentum and thermal field calculations, despite their known underprediction of wall temperature. In this paper, a novel framework using a branch of machine learning, geneexpression programming (GEP) [Zhao et al. 2020, J. Comp. Physics, 411:109413] is used to develop closures for the turbulent heat-flux to improve upon this underprediction. In the original use of GEP (“frozen” approach), the turbulent heat-flux from a high-fidelity database was used to evaluate the fitness of the candidate closures during the symbolic regression, however, the resulting closure had no information of the temperature field during the optimisation process. In this work, the regression process of the GEP instead incorporates RANS calculations to evaluate the fitness of the candidate closures. This allows the inclusion of the temperature field from RANS to advance the iterative regression, leading to a more integrated heat-flux closure development, and consequently more accurate and robust models. The GEP-based CFD-driven framework is demonstrated on a trailing edge slot configuration with three blowing ratios. Full a posteriori predictions from the new closures are compared to high-fidelity reference data and both conventional RANS closures and closures obtained from the “frozen” approach.

Water hammer is a principal cause of pipeline and equipment failure in pumping systems. The numerical method and experiments are used to investigate the dynamic interaction between the valve-closure water hammer wave and pump, to study the pressure variation and fluid-induced force on the pump components. The impeller-volute interaction and impeller position are taken into consideration. Results show that the valve-closure water hammer wave generates a substantial fluid-induced force on the pump and leads to a pressure surge in the pipeline. Meanwhile, the impeller-volute interaction also causes pressure and force variation in the pipeline and pump. The force amplitude caused by this factor in the axial direction is similar to that caused by the water hammer wave but is much smaller in the radial direction. The different interaction position of the water hammer wave on the blades can weaken the force, by 13.11% and 13.18% for the impeller and volute when the blades are under the most optimal position, respectively.

The pre-swirl system is of great importance for temperature drop and cooling air supply. This study aims to investigate the influencing mechanism of heat transfer, nonuniform thermodynamic characteristics, and cooling air supply sensitivity in a pre-swirl system by the application of the flow control method of the pre-swirl nozzle. A novel test rig was proposed to actively control the supplied cooling air mass flow rate by three adjustable pre-swirl nozzles. Then, the transient problem of the pre-swirl system was numerically conducted by comparison with 60°, 120°, and 180° rotating disk cavity cases, which were verified with the experiment results. Results show that the partial nozzle closure will aggravate the fluctuation of air supply mass flow rate and temperature. When three parts of nozzles are closed evenly at 120° in the circumferential direction, the maximum value of the nonuniformity coefficient of air supply mass flow rate changes to 3.1% and that of temperature changes to 0.25%. When six parts of nozzles are closed evenly at 60° in the circumferential direction, the maximum nonuniformity coefficient of air supply mass flow rate changes to 1.4% and that of temperature changes to 0.20%. However, different partial nozzle closure modes have little effect on the average air supply parameters. Closing 14.3% of the nozzle area will reduce the air supply mass flow rate by 9.9% and the average air supply temperature by about 1 K.

International audience; An original dynamic model for substrate uptake under transient conditions is established and used to simulate a variety of biological responses to external perturbations. The actual uptake and growth rates, treated as cell properties, are part of the model variables as well as the substrate concentration at the cell-liquid interface. Several regulatory loops inspired by the structure of the glycolytic chain are considered to establish a set of ordinary differential equations. The uptake rate evolves so as to reach an equilibrium between the cell demand and the environmental supply. This model does not contain any of the usual algebraic closure laws relating to the instantaneous uptake, growth rates, and the substrate concentration, nor does it enforce the continuity of mass fluxes at the liquid-cell interface. However, these relationships are found in the steady-state solution. Previously unexplained experimental observations are well reproduced by this model. Also, the model structure is suitable for further coupling with flux-based metabolic models and fluid-flow equations.

A computational fluid dynamics (CFD) compatible and fully local transition closure model is proposed for three-dimensional hypersonic boundary layers considering crossflow effects. The transition m...

In the current paper, numerical simulations of the combustion of turbulent CH4-H2 are presented employing the standard k-epsilon and the RNG k-epsilon for turbulence closure. The Fr-ED concept is carried out to account for chemistry/ turbulence interaction. The hydrogen content is varied in the fuel stream from 0% to 100%. The numerical solutions are validated by comparison with corresponding experimental data from the Combustion Laboratory of the University of Milan. The flow is directed radially outward. This method of fuel injection has been already been explored experimentally. The results show that the structure of the flame is described reasonably and both standard k-ɛ and RNG k- ɛ models can predict the flame shape. The general aspect of the temperature profiles is well predicted. The temperature profiles are indicating a different trend between CH4 and CH4/H2 fuel mixtures.

The undesired and unexpected closure of valves in pipelines is the most frequent failure that causes interruptions in the transport of natural gas. This work aims at the detection of valve closures...

A recent analysis (Lipatnikov et al., 2020) of complex-chemistry direct numerical simulation (DNS) data obtained from lean hydrogen-air flames associated with corrugated-flame (case A), thin-reaction-zone (case B), and broken-reaction-zone (case C) regimes of turbulent burning has shown that the flamelet concept (i) can predict mean concentrations of various species in those flames if the probability density function (PDF) for the fuel-based combustion progress variable c is extracted from the DNS data, but (ii) poorly performs for the mean rate W¯c of product creation. These results suggest applying the concept to evaluation of mean species concentration (but not the mean rate) in combination with another closure relation for W¯c whose predictive capabilities are better. This proposal is developed in the present paper whose focus is placed on studying a new flamelet-based presumed PDF P(c) for predictions of mean concentration of radicals in engineering computational fluid dynamics (CFD) applications. Analysis of the DNS data shows that (i) the flamelet PDF performs well at intermediate values of c in cases A and B, but should be truncated at small and large c, (ii) modeling P(c) in the radical recombination zone (i.e., at large c) is of importance for predicting mean concentrations of H,O, and OH. Accordingly, the flamelet PDF is truncated and combined with a uniform P(c) at large c. Moreover, the mean rate W¯c extracted from the DNS data is used to calibrate the PDF (the rate is considered to be given by another model). Assessment of the approach against the DNS data shows that it well predicts mean density, temperature, and concentrations of reactants, product, and the aforementioned radicals in cases A and B. In case C, the approach performs worse for OandOH at large c¯ and moderately underestimates the mean concentration of H in the entire flame brush.

A paradigm shift in the government’s energy policy was reflected in its declaration of early closure of old nuclear plants as well as cancellation of plans for the construction of new plants. To this end, unit 1 of Kori Nuclear Power Plant was permanently shut down and is set for decommission. Based on these changes, the off-site transport of spent fuels from nuclear power plants has become a critical issue. The purpose of this study is to develop an optimized method for transportation of spent fuels from Kori Nuclear Power Plant’s units 1, 2, 3, and 4 to an assumed interim storage facility by simulating the scenarios using the Flexsim software, which is widely used in logistics and manufacturing applications. The results of the simulation suggest that the optimized transport methods may contribute to the development of delivery schedule of spent fuels in the near future. Furthermore, these methods can be applied to decommissioning plan of nuclear power plants.

Qualitative conditionals of the form “If A, then usually B” are often used to model nonmonotonic inference relations. Evaluating conditionals as three valued logical objects, allows for a classification of all conditionals over a given propositional signature. These classes of conditionals and their properties in terms of nonmonotonic inference are useful for the task of calculating the closures of concrete nonmonotonic inference relations. In this paper, we present a rigorous classification of conditionals in terms of semantic properties. We also present and evaluate an approach for calculating closures of inference relations by exploiting our classification of conditionals. We discuss the usefulness of the availability of the complete closure of inference relations by using the results of our approach to systematically evaluate several inference relations with respect to postulates proposed for nonmonotonic inference relations.

Investigations of void distributions and formation mechanisms of proppant particles in closure fractures have extremely major significance for improving the production of coalbed methane. In this study, a numerical method was developed to simulate compaction processes of a proppant-filled fracture under different closure stresses. The particle trajectories, force chains and coordination numbers of proppants were extracted to analyze and investigate void ratio distributions and associated formation mechanisms. The results showed that during fracture closures from the top to bottom, some particles in the top layer of the proppant-filled fracture moved into the middle layer, which made the middle layer particles formed solid force-bearing structures. The greatest force was transmitted between particles in the middle layer. This was followed by particles in the top layer and finally, the bottom layer. In addition, the proportions of large coordination numbers, and average coordination numbers of the middle layer were the largest, followed by those of the top and bottom layers, which reflected that the particles of the middle layer were denser than those of the other two layers. The above factors caused the void ratios of the middle layer to be the lowest, followed by those of the top and bottom layer, respectively.

A computational model is established to investigate the effects of a periodic gust flow on the wake structure of ventilated supercavities. The effectiveness of the computational model is validated by comparing with available experimental data. Benefited from this numerical model, the vertical velocity characteristics in the entire flow field can be easily monitored and analyzed under the action of a gust generator; further, the unsteady evolution of the flow parameters of the closed region of the supercavity can be captured in any location. To avoid the adverse effects of mounting struts in the experiments and to obtain more realistic results, the wake structure of a ventilated supercavity without mounting struts is investigated. Unsteady changes in the wake morphology and vorticity distribution pattern of the ventilated supercavity are determined. The results demonstrate that the periodic swing of the gust generator can generate a gust flow and, therefore, generate a periodic variation of the ventilated cavitation number σ. At the peak σ, a re-entrant jet closure appears in the wake of the ventilated supercavity. At the valley σ, a twin-vortex closure appears in the wake of the ventilated supercavity. For the forward facing model, the twin vortex appears as a pair of centrally rolled-up vortices, due to the closure of vortex is affected by the structure. For the backward facing model, however, the twin vortex appears alternately as a pair of centrally rolled-up vortices and a pair of centrally rolled-down vortices, against the periodic gust flow.

Commercial space transportation is becoming more affordable and accessible. Consequently, we expect to see significant expansion of commercial space launch activities in the coming decade. As space vehicles travel through airspace during the launch and re-entry stages, they potentially disrupt the regular operations of traditional users. This paper estimates the potential economic and operational impacts of commercial space horizontal launch activities on airlines under various launch scenarios using predictive fast-time simulation modeling, focusing on Cecil Air and Space Port in Jacksonville (Florida) and the rules governing the national airspace system (NAS) in the United States. Our results indicate that the existing 4-hour airspace closure rule impacts a significant number of flights, resulting in flight time delays, additional flight distance and fuel burn, as well as other direct operating costs. Safely reducing the duration of airspace closures could serve as a simple solution to mitigate the impacts on airlines and other traditional NAS users. More importantly, treating our studied launch vehicle as an aircraft and opening its departure/arrival corridor to air traffic during a horizontal launch and return would potentially reduce the impacts on airlines significantly, depending on the location of the spaceport, planned flight paths and the trajectory of the launch.

This paper takes advantage of a natural experiment involving subway station closures to examine how subway ridership is associated with the impact of robbery victimization within spatial network buffers immediately surrounding subway stations in Bronx (County), New York. The New York City subway system is the busiest in the USA, with an annual ridership estimated at 1.8 billion people. Key findings of this research include noteworthy relationships between robbery hot spots and subway stations, as well as substantial reductions in robbery frequency during temporary subway station closures, with larger reductions occurring in closer proximities to the subway stations. There was also a significant robbery pattern “normalization process” that occurred after the closed subway stations were reopened where robbery frequency returned to historically “normal” pre-closure levels. These notable decreases of crime in and around subway stations during the station closure time periods, as well as the prominent increases in robbery when subway stations reopened, should be taken into consideration when planning transit maintenance, conducting crime prevention initiatives, and scheduling crime control strategies.

Earthen manure storage (EMS) facilities no longer in operation present a risk to the environment, and there is limited guidance to support the planning and implementation of EMS closures. A combined dairy and feedlot in southern Alberta, Canada, had an EMS in operation for about 55 yr. The dairy portion ceased operation in 2015, and the EMS was emptied; however, no specific steps for permanent closure to minimize possible contamination were followed. The objective of this study was to document changes in shallow groundwater quality following an EMS closure. This EMS was already instrumented to assess its effect on the groundwater quality as part of a long-term study prior to closure. Eight groundwater monitoring wells were installed 2-38 m from the EMS in up- and downgradient positions in 2010 and 2011. Groundwater samples were collected about three times annually prior to and for 4 yr after the EMS closure and were analyzed for NO3 -N, NH3 -N, and Cl- . Wells screened at more than 8 m deep were not affected by the EMS prior to or after closure. However, in shallower wells, groundwater NO3 -N concentration increased to a maximum 3 yr after closure (in 2018) and then decreased afterward. In a shallow well 40 m downgradient from the EMS, the NO3 -N concentrations decreased from 31 mg L-1 in 2015 to 5 mg L-1 in 2019, and the Cl- concentration decreased from 64 to 53 mg L-1 , suggesting the contamination plume had dispersed. However, the EMS was still a source of contamination because high concentrations of NO3 -N (0.05-40 mg L-1 ) and Cl- (43-862 mg L-1 ) were present in wells adjacent to the EMS 4 yr after closure.

While significant increase in turbulent burning rate in lean premixed flames of hydrogen or hydrogen-containing fuel blends is well documented in various experiments and can be explained by highlighting local diffusional-thermal effects, capabilities of the vast majority of available models of turbulent combustion for predicting this increase have not yet been documented in numerical simulations. To fill this knowledge gap, a well-validated Turbulent Flame Closure (TFC) model of the influence of turbulence on premixed combustion, which, however, does not address the diffusional-thermal effects, is combined with the leading point concept, which highlights strongly perturbed leading flame kernels whose local structure and burning rate are significantly affected by the diffusional-thermal effects. More specifically, within the framework of the leading point concept, local con sumption velocity is computed in extremely strained laminar flames by adopting detailed combustion chemistry and, subsequently, the computed velocity is used as an input parameter of the TFC model. The combined model is tested in RANS simulations of highly turbulent, lean syngas-air flames that were experimentally investigated at Georgia Tech. The tests are performed for four different values of the inlet rms turbulent velocities, different turbulence length scales, normal and elevated (up to 10 atm) pressures, various H2/CO ratios ranging from 30/70 to 90/10, and various equivalence ratios ranging from 0.40 to 0.80. All in all, the performed 33 tests indicate that the studied combination of the leading point concept and the TFC model can predict well-pronounced diffusional-thermal effects in lean highly turbulent syngas-air flames, with these results being obtained using the same value of a single constant of the combined model in all cases. In particular, the model well predicts a significant increase in the bulk turbulent consumption velocity when increasing the H2/CO ratio but retaining the same value of the laminar flame speed.

In this paper, neural network (NN)-based models are generated to replace flamelet tables for sub-grid modeling in large-eddy simulations of a single-injector liquid-propellant rocket engine. In the most accurate case, separate NNs for each of the flame variables are designed and tested by comparing the NN output values with the corresponding values in the table. The gas constant, internal flame energy, and flame heat capacity ratio are estimated with 0.0506%, 0.0852%, and 0.0778% error, respectively. Flame temperature, thermal conductivity, and the coefficient of heat capacity ratio are estimated with 0.63%, 0.68%, and 0.86% error, respectively. The progress variable reaction rate is also estimated with 3.59% error. The errors are calculated based on mean square error over all points in the table. The developed NNs are successfully implemented within the CFD simulation, replacing the flamelet table entirely. The NN-based CFD is validated through comparison of its results with the table-based CFD., Comment: This paper is accepted for publication in the AIAA Journal

In numerical simulations of deep convection at kilometer-scale horizontal resolutions, in-cloud subgrid-scale (SGS) turbulence plays an important role in the transport of heat, moisture, and other scalars. By coarse graining a 50 m high-resolution large-eddy simulation (LES) of an idealized supercell storm to kilometer-scale grid spacings ranging from 250 m to 4 km, the SGS fluxes of heat, moisture, cloud, and precipitating water contents are diagnosed a priori. The kilometer-scale simulations are shown to be within the “gray zone” as in-cloud SGS turbulent fluxes are comparable in magnitude to the resolved fluxes at 4 km spacing, and do not become negligible until ~500 m spacing. Vertical and horizontal SGS fluxes are of comparable magnitudes; both exhibit nonlocal characteristics associated with deep convection as opposed to local gradient-diffusion type of turbulent mixing. As such, they are poorly parameterized by eddy-diffusivity-based closures. To improve the SGS representation of turbulent fluxes in deep convective storms, a scale-similarity LES closure is adapted to kilometer-scale simulations. The model exhibits good correlations with LES-diagnosed SGS fluxes, and is capable of representing countergradient fluxes. In a posteriori tests, supercell storms simulated with the refined similarity closure model at kilometer-scale resolutions show better agreement with the LES benchmark in terms of SGS fluxes than those with a turbulent-kinetic-energy-based gradient-diffusion scheme. However, it underestimates the strength of updrafts, which is suggested to be a consequence of the model effective resolution being lower than the native grid resolution.

An approach for the optimization of turbulent flow in diffusers is presented. A methodology is developed to integrate a finite volume-based computational fluid dynamics (CFD) model and an optimization tool uses micro-genetic algorithms (u GA). The CFD model is based on the Reynolds-averaged Navier-Stokes equations, with the standard k-e closure turbulence model. This methodology is tested on two cases. The first is the estimation of the conical diffuser length, which gives the maximum pressure recovery coefficient, for a given diffuser area ratio. Good agreement between the computational and experimental results is obtained. The second case is the optimization through wall contouring of a given two-dimensional diffuser area ratio and length ratio. The results indicate that the diffuser performance can be improved by this method.

Acid-fracturing operations are applied to improve the productivity of carbonate reservoirs by creating rough fracture surfaces that remain conductive for reservoir fluids after the fracture closure...

In this paper, we investigated a pyramidal hopper with extended discharge at the exit to make a bag of particles to a designated weight. Any feedback control strategy cannot be applied because the exit gate does not have any encoders to check its size, the gate size cannot be adjusted precisely during the closing motion, and the speed of the closing gate is relatively slow compared to the discharge rate of the particles. By only processing the weighing scale measurement in real time, we need to find the best point of time to start the exit gate closure of the pyramidal hopper to fill precise amount of particles into the bag. We developed and compared two control methods to determine appropriate point to initiate gate closure. First, we developed a control method by applying an empirical model describing the correlation between the gate size and the particle discharge rate, which is established by thorough experiments. Second, we developed a control method using curve fitting to predict the discharge rate of particles during gate closing motion without experiment. Both control methods were demonstrated using real time experiments, and the first one with an empirical model showed better result for final weight. This method can be directly applied to weight control of bag filling hopper without modifying the hardware system.

Mentoring programs are a popular approach to preventing problem behavior and promoting positive youth development. However, mentoring relationships that end prematurely may have negative consequences for youth. Previous research has investigated match-level indicators of premature match closure, highlighting possible individual mentor- or mentee-level characteristics that might influence the match staying together. However, less work has investigated the importance of program-level variables in match retention. Mentor training and support may be one key modifiable program-level feature that could curtail the risk of premature match closure. In this study, we used data from a national survey of youth mentoring programs (N = 1451) to examine training and other potential predictors of premature match closures (Garringer et al. 2017). We used a Bayesian Additive Regression Trees (BART) model to predict program-reported premature match closure rates from a set of four training-related variables and 26 other covariates (e.g., program size, budget, demographic composition). Findings indicate that the set of predictors explained about one-fifth of the variation in reported rate of premature match closure (cumulative pseudo R2 = .21), and the strongest, and only statistically significant, predictor of premature match closure was the frequency of ongoing training and support contacts per month. Overall, findings indicate that there is substantial noise in predicting program-reported premature match closure, but program-reported provision of ongoing training and support seems to emerge as a relatively stable signal in the noise.