Field Cores Research Articles

Waves in Earth's core and geomagnetic field forecast

We use advanced numerical geodynamo series to derive a reduced stochastic model of the dynamics at the surface of Earth's core. Considering order 3 autoregressive (AR-3) processes allows to replicate the simulated spatiotemporal spectrum over a broad range of time-scales, spanning millennia to a fraction of year, including the cut-off found for periods shorter than approximately 2 years and associated with magnetic dissipation. We show how to derive such a forward model from a variety of input simulation series, and present its implementation into the pygeodyn data assimilation algorithm, based on a sequential ensemble method. The updated scheme is applied to perform magnetic field hindcasts and core flow reanalyses. For all observable length-scales, the rate of change of the observed magnetic field is most of the time accounted for within the spread of the forward model trajectories. AR-3 predictions on average supersede by about 35 % linear extrapolations on short (2 yr) time-scales, reducing high-frequency spurious variations in reanalysed flow motions. This improvement is reduced to ≈10% for 5 yr increments, with a large variability from one epoch to the other depending on the overall curvature of the magnetic field evolution. We perform a reanalysis over the period 1880–2023 covered by observatory and satellite records. We find enhanced kinetic energy in three period ranges around 12.5, 6.5 and 3.5 years. At all three periods, fluid motions share geometrical properties compatible with quasi-geostrophic magneto-Coriolis waves: equatorial symmetry, larger amplitude near the equator, flow dominated by low azimuthal wave number and modulated in longitude, phase speed much faster than the fluid velocity and decreasing with the period. At 6.5 yr period we trace back to the mid-1990's the patterns previously detected from satellite data. We also find in the 1960–70's a similar wave-train, possibly in link with the 1969 geomagnetic jerk. The AR-3 model, in conjunction with early satellite records, likely helps isolate such coherent features on interannual time-scales. Similar wave-like motions also show up at 3.5 yr period around 1970 and during the past decades. At periods around 12.5 yr we detect recurrent patterns starting as far back as 1920, and modulated over decadal time-scales. Our results show growing evidence for core dynamics governed by the presence of hydro-magnetic waves over a wide range of periods. This may allow deterministic and/or empirical descriptions of the signal that may help sound deep Earth's properties, and improve predictions of the magnetic field evolution.

MODERN METHODS OF GEOLOGICAL EXPLORATION: TECHNOLOGICAL ACHIEVEMENTS AND INNOVATIONS

Modern geological exploration has undergone significant transformations due to advancements in technology. Traditional methods, such as field surveys, core sampling, and basic geophysical techniques, are being supplemented or replaced by cutting-edge innovations that improve precision, efficiency, and environmental sustainability. This article examines these technological achievements, highlighting key developments such as 3D seismic imaging, electromagnetic surveys, and remote sensing via drones and satellite imagery.

Multiscale Characterization of Fractures and Analysis of Key Controlling Factors for Fracture Development in Tight Sandstone Reservoirs of the Yanchang Formation, SW Ordos Basin, China

Tight sandstone reservoirs, despite their low porosity and permeability, present considerable exploration potential as unconventional hydrocarbon resources. Natural fractures play a crucial role in hydrocarbon migration, accumulation, and present engineering challenges such as late-stage reformation in these reservoirs. This study examines fractures in the seventh member of the Triassic Yanchang Formation’s tight sandstone within the Ordos Basin using a range of methods, including field outcrops, core samples, imaging and conventional logging, thin sections, and scanning electron microscopy. The study clarifies the characteristics of fracture development and evaluates the relationship between dynamic and static rock mechanics parameters, including the calculation of the brittleness index. Primary factors influencing fracture development were quantitatively assessed through a combination of outcrop, core, and mechanical test data. Findings reveal that high-angle structural fractures are predominant, with some bedding and diagenetic fractures also present. Acoustic, spontaneous potential, and caliper logging, in conjunction with imaging data, enabled the development of a comprehensive probabilistic index for fracture identification, which produced favorable results. The analysis identifies four key factors influencing fracture development: stratum thickness, brittleness index, lithology, and rock mechanical stratigraphy. Among these factors, stratum thickness is negatively correlated with fracture development. Conversely, the brittleness index positively correlates with fracture development and significantly influences fracture length, aperture, and linear density. Fractures are most prevalent in siltstone and fine sandstone, with minimal development in mudstone. Different rock mechanics layer types also impact fracture development. These insights into fracture characteristics and controlling factors are anticipated to enhance exploration efforts and contribute to the study of similar unconventional reservoirs.

Assessing cracking resistance and threshold limits of bituminous mixtures with IDEAL-CT and predictive modeling techniques

This paper presents a comprehensive study to establish the threshold limit of CTIndex for the Marshall mixes. The study also aims to assess the impact of different design factors on the cracking resistance of bituminous mixtures using the Indirect Tensile Asphalt Cracking Test (IDEAL-CT) test. This study considers 2 different aggregate sources, 2 different gradations, 5 different types of Design Aggregate Gradation (DAG), 3 binder types, and 5 levels of compactive effort. The test results show that higher cracking resistance can be achieved using a smaller nominal maximum size of the aggregate (NMAS), finer gradation, modified binder, and decreased compactive effort with aggregates having low abrasion and absorptive characteristics. This study also comprehends the influence of volumetric parameters of the bituminous mixes on fracture resistance. It was found that at a particular Optimum Binder Content (OBC), higher bulk specific gravity of the compacted specimen (Gmb) and voids filled with asphalt (VFA) result in reduced CTIndex, specifying poor cracking performance. While higher air voids (AV) and voids in mineral aggregate (VMA) lead to increased CTIndex, indicating better-cracking resistance. Statistical analysis tools were used to evaluate the significance of the influential factors that are affecting the cracking potential of the mix. Different Machine learning models were also developed to predict CTIndex based on the design factors considered in the study. The random forest (RFR) model showed strong accuracy, reflected by low Mean Absolute Error (MAE=3.16), Mean Absolute Percentage Error (MAPE=9.57), Root Mean Square Error (RMSE=4.23), and a high coefficient of determination (R²=0.95) value, notifying a precise fit and reliable predictions. Additionally, a GUI has been also developed to enhance the practical usability of the model for wider usage. Further, the present study proposes the threshold value of CTIndex for the selection of crack-resistant bituminous mixtures. Moreover, the study investigated the correlation between laboratory and field compaction methods and validated the initial threshold specification of CTIndex for the Marshall mixes. Despite of the variations in different compaction methodologies and specimen thickness, a strong positive correlation (R² > 0.76) between laboratory and field cores of BC-1 and DBM-2 indicates that the performance criteria are adequate and justified.

Laboratory and Field Performance Evaluation of NMAS 9.5, 8.0, and 5.6 mm SMA Mixtures for Sustainable Pavement

This study evaluates the laboratory and field performance of stone mastic asphalt (SMA) mixtures with nominal maximum aggregate sizes (NMAS) of 9.5, 8.0, and 5.6 mm. Aggregates and fine aggregates of these sizes were produced using an impact crusher and a polyurethane screen. Mix designs for SMA overlays on aged concrete pavement were developed. Laboratory tests assessed rutting performance using full-scale accelerated pavement testing (APT) equipment and reflective cracking resistance using an asphalt mixture performance tester (AMPT). Field evaluations included noise reduction using CPX equipment, skid resistance using SN equipment, and bond strength using field cores. Results showed that for 8.0 mm SMA mixtures to achieve the same rutting performance as 9.5 mm SMA, PG76-22 grade binder was required, whereas 5.6 mm SMA required PG82-22. The 8.0 and 5.6 mm SMA mixtures showed 22.2% and 25% reduced crack progression, respectively, compared with the 9.5 mm SMA mixtures. Field evaluations indicated that 8.0 mm and 5.6 mm SMA pavements reduced tire–pavement noise by 1.7 and 0.8 dB, increased skid resistance by 8.5% and 2.0%, and enhanced shear bond strength by 150%, compared with 9.5 mm SMA. Overall, the 8.0 mm SMA mixture on aged concrete pavement demonstrated superior durability and functionality toward sustainable pavement systems.

Evaluating dynamic modulus of cold in-place recycling mixture with foamed bitumen using field core samples

This study evaluates the dynamic modulus of Cold In-Place Recycling with Foamed Bitumen (FB-CIR) pavements, focusing on the influence of various recycled materials—reclaimed asphalt pavement (RAP), reclaimed inorganic binder stabilized aggregate (RAI), and their combination (RAP+RAI). Core samples from three representative FB-CIR projects in China were tested using the MTS-130 system across temperatures of −10°C, 5°C, 20°C, 35°C, and 50°C, and frequencies ranging from 25 Hz to 0.1 Hz. Statistical analysis and the Sigmoidal model were employed to analyze the viscoelastic behavior and establish the master curve for the FB-CIR dynamic modulus. The dynamic modulus of the three FB-CIR mixtures showed pronounced frequency-dependence, decreasing with reduced frequencies, and exhibited temperature sensitivity, with lower values at elevated temperatures. FB-RAI consistently demonstrated higher modulus values due to the hydration of previously unhydrated cement particles, while FB-RAP and FB-RAP+RAI displayed lower values, as RAP behaves similarly to unbound granular material. The construction of the master curve, based on the time-temperature superposition principle, enhanced our understanding of FB-CIR mixtures' mechanical behavior and enabled accurate extrapolation of dynamic modulus values across diverse conditions. Furthermore, FB-RAI's narrow phase angle variation indicates its superior mechanical stability and reduced sensitivity to external changes, making it ideal for areas with extreme climate fluctuations or heavy traffic. The study also identified three distinct phase angle variation patterns in FB-CIR mixtures, underscoring the importance of nuanced pavement design strategies that consider temperature, frequency, and material composition to optimize the performance and durability of FB-CIR pavements.

Structural detachment influences the shale gas preservation in the Wufeng-Longmaxi Formation, Northern Guizhou Province

Abstract In order to reveal the restriction in shale gas enrichment of the Wufeng-Longmaxi Formation in the northern Guizhou province, the influence model of detachment layer was established through field geological investigation, core observation, logging, sample analysis, and geological background data. The response relationship between the detachment layer and the shale gas enrichment model in different structural formats was analyzed. The results show that the thickness of the Wufeng-Longmaxi Formation’s detachment layer is influenced by the conditions near the fault zones and mineralogical characteristics. The lithofacies of the detachment layer shows mainly a combination of clay-rich shale facies. This indicates that lithofacies type is one of the main factors influencing the variation in slip layer thickness. The detachment layer exhibits distinct well logging response characteristics and is influenced by nitrogen enrichment. The development of detachment fractures allows atmospheric nitrogen to infiltrate shale gas. It leads to poor gas saturation in the shale gas. In addition, the overall tectonic deformation in the northern Guizhou province was found to gradually intensify from Northwest to Southeast, and there were two tectonic models: a slot-shift tape transition belt and a spacer type deformation belt. The influence of decollements on shale gas preservation was barely found in the northern Guizhou province. It is mainly controlled by buried depth of the target layer, conditions of the cover layer, structural type, and deformation intensity.

Early Planet Formation in Embedded Disks (eDisk). XV. Influence of Magnetic Field Morphology in Dense Cores on Sizes of Protostellar Disks

The magnetic field of a molecular cloud core may play a role in the formation of circumstellar disks in the core. We present magnetic field morphologies in protostellar cores of 16 targets in the Atacama Large Millimeter/submillimeter Array large program “Early Planet Formation in Embedded Disks (eDisk),” which resolved their disks with 7 au resolutions. The 0.1 pc scale magnetic field morphologies were inferred from the James Clerk Maxwell Telescope POL-2 observations. The mean orientations and angular dispersions of the magnetic fields in the dense cores are measured and compared with the radii of the 1.3 mm continuum disks and the dynamically determined protostellar masses from the eDisk program. We observe a significant correlation between the disk radii and the stellar masses. We do not find any statistically significant dependence of the disk radii on the projected misalignment angles between the rotational axes of the disks and the magnetic fields in the dense cores, nor on the angular dispersions of the magnetic fields within these cores. However, when considering the projection effect, we cannot rule out a positive correlation between disk radii and misalignment angles in three-dimensional space. Our results suggest that the morphologies of magnetic fields in dense cores do not play a dominant role in the disk formation process. Instead, the sizes of protostellar disks may be more strongly affected by the amount of mass that has been accreted onto star+disk systems, and possibly other parameters, for example, magnetic field strength, core rotation, and magnetic diffusivity.

Evolution mechanism and interaction of the muzzle combustion-gas jets field of underwater dual-barrel synchronized launch

Despite a certain amount of research that has been done on the muzzle combustion–gas jet field of underwater launching in recent years, there are still few reports on the evolution mechanism and interaction of underwater dual-barrel synchronised launch flow fields. To fill this gap, this study aimed to numerically analyse the effects of different barrel intervals on the transient jet field evolution characteristics of the dual-barrel launch. The three-dimensional unsteady multi-phase mathematical model was created and compared with an underwater sealed emission experiment of data for verification. The volume of fluid multi-phase flow model is used to describe the gas–liquid two-phase flow process, and the k–ε turbulence model simulates the turbulent mixing phenomenon in the jet field. On this basis, the user-defined function coupling internal ballistics process was used to determine the transient jet field of a double-barrelled, 30 mm (d = 30) underwater artillery numerically at the barrel intervals of 3d, 4d and 5d. The calculation results indicate that the closer the interval is, the more chaotic the pressure field is, and the Mach disc structure forms later. When the barrel interval is 3d, the Mach disc formation time is ∼ 0.2 ms, while it forms at ∼ 0.15 ms when the barrel interval is 5d. The movement law of projectiles in water is consistent with the change of Mach disc displacement with time, and both satisfy the exponential growth law. The velocity field core is elliptical, and the vortices on both sides of the muzzle continue to grow within 0.4 ms when the launch interval is 3d. As the barrel interval increases, the core of the velocity field is bottle-shaped, the vortex on both sides of the muzzle increases first and then decreases within 0.4 ms, and the maximum temperature of the flow field increases by 15 %.

Evaluation of Fatigue Behavior of Asphalt Field Cores Using Discrete Element Modeling.

Fatigue cracking is one of the primary distresses of asphalt pavements, which significantly affects the asphalt pavement performance. The fatigue behavior of the asphalt mixture observed in the laboratory test can vary depending on the type of fatigue test and the dimension and shape of the test specimen. The variations can make it difficult to accurately evaluate the fatigue properties of the field asphalt concrete. Accordingly, this study proposed a reliable method to evaluate the fatigue behavior of the asphalt field cores based on discrete element modeling (DEM). The mesoscopic geometric model was built using discrete element software PFC (Particle Flow Code) and CT scan images of the asphalt field cores. The virtual fatigue test was simulated in accordance with the semi-circular bending (SCB) test. The mesoscopic parameters of the contacting model in the virtual test were determined through the uniaxial compression dynamic modulus test and SCB test. Based on the virtual SCB test, the displacement, contact forces, and crack growth were analyzed. The test results show that the fatigue life simulated in the virtual test was consistent with that of the SCB fatigue test. The fatigue cracks in the asphalt mixture were observed in three stages, i.e., crack initiation, crack propagation, and failure. It was found that the crack propagation stage consumes a significant portion of the fatigue life since the tensile contact forces mainly increase in this stage.

Development of a micro-infrared thermometry method for surface temperature distribution and variation of millimeter particle during high-temperature reaction

Temperature strongly affects the conversion efficiency, local reactivity, and particle stabilization of the reactions, particularly at high temperature. This study integrated infrared thermography with a high-temperature hot stage reactor to develop a methodology of continuous temperature measurement for a single particle reaction at high temperatures. The external optical transmission transmittance and temperature field core were corrected, and the relationship between the measured temperature (Tr) and true temperature (T0) was obtained by adjusting the sample emissivity. Sample temperature with known emissivity at elevated temperature was measured with 1% deviation. The instantaneous temperature measurement for the gasification process was carried out and the overall emissivities of coal particles were corrected. Temperature distribution and variation on the coal particle surface during the gasification process were further obtained and consistent with the previous research results. The proposed online temperature measurement method provides a new approach for gaining insights into particle reaction states.

Magneto Axisymmetric Vibration of FG-GPLs Reinforced Annular Sandwich Plates with an FG Porous Core Using DQM and a New Shear Deformation Theory

Based on the differential quadrature procedure (DQP), the vibrational response of functionally graded (FG) sandwich annular plates enhanced with graphene platelets (GPLs) and with an FG porous core is illustrated in this paper. The current annular plate is assumed to deform axisymmetrically and expose to a radial magnetic field. The Lorentz magnetic body force is deduced via Maxwell’s relations. The effective physical properties of the upper and lower layers of the sandwich plate are obtained by employing the Halpin–Tsai model. Our technique depends on a new four-unknown shear deformation theory to depict the displacements. In addition, the motion equations are established via Hamilton’s principle. The motion equations are solved by employing the DQP. In order to study the convergence of the DQ method, the minimum number of grid points needed for a converged solution is ascertained. In addition, the current theory’s outcomes are compared with those of previous higher-order theories. The effects of the porosity distribution type, porosity factor, GPLs distribution pattern, GPLs weight fraction, inner-to-outer radius ratio, outer radius-to-thickness ratio, magnetic field parameters, core thickness, and elastic substrate parameters on the nondimensional vibration frequencies are discussed.

Development of Macrotexture Test Method for Dense-Graded Asphalt Mixtures

The design and construction of pavements necessitate careful consideration of longevity, cost-effectiveness, sustainability, and safety, with a focus on enhancing the durability and lifespan of dense-graded asphalt (DGA) surface mixtures. This paper discusses a research project the Federal Highway Administration (FHWA) initiated to assess the macrotexture characteristics of DGA mixture pavement—particularly concerning safety at higher speeds. The project aims to develop an efficient testing procedure for measuring macrotexture during mixture design and field-testing processes, striking a balance between longevity, cost-effectiveness, sustainability, and safety in pavement design and construction. The study began with a comprehensive review of existing practices, leading to the selection and testing of a unique laser texture scanner capable of noncontact macrotexture measurement. The subsequent phase involved validating the suggested macrotexture measurement system through data collected from State-sponsored projects under the FHWA Mobile Asphalt Technology Center program. Macrotexture measurements were collected from field cores and laboratory-compacted specimens from various State departments of transportation projects and analyzed. Preliminary analysis of the limited dataset to date revealed a positive correlation between average macrotexture measurements from gyratory specimens’ top surface and field core macrotexture measurements. The FHWA developed a draft test method for measuring macrotexture on laboratory specimens and field cores, thereby aiming to reduce procedural variability. Interlaboratory macrotexture test results demonstrated good reproducibility, with an average coefficient of variation of approximately 20%. Overall, this research project seeks to advance the understanding and measurement of macrotexture in DGA mixture pavements and thereby contribute to the development of safe pavements.

Provenance signature and tectono–sedimentary setting of the Permian Shihezi formation (Ordos basin, China): Insights from geochemistry and detrital zircon U–Pb dating

During the depositional period of the Permian Shihezi Formation, the southern margin of the Ordos Basin was a key location for studying the tectonic movement of the North China Craton (NCC) and South China Blocks. The sedimentary environment was the first period of complete transition from marine to continental. However, the distribution of sediments controlled by a multi–provenance supply and the response of deposition to tectonics remain ambiguous, and the restoration of paleogeography remains in the qualitative stage, restricting the study of larger-scale tectono–sedimentary patterns. Based on field profiles and core observations, the paleocurrent direction, lithic fragments, heavy mineral assemblages, rare earth element distribution patterns, 11 detrital zircon U–Pb age datasets, and discrimination diagram of major and trace elements, the provenance signature and tectono–sedimentary setting were revealed. The results indicated that there are three main provenances in the southern margin of the Ordos Basin: North Qilian and western and eastern sections of the North Qinling Orogenic Belt. The tectonic setting of the North Qilian was a continental island arc, and the North Qinling was transformed from a passive to an active continental margin. Owing to the continued intense tectonic activities of the North Qilian, a braided river delta with a large sedimentary range developed in the west, and it was mixed with detrital sediments from the western section of the North Qinling with weak tectonic activity in the central. Affected by the uplift of the southern North China Craton, the sedimentary environment in the eastern range was unstable, and the thickness distribution of sandy sediments in the braided river delta was uneven. Refinement of provenance and deposition has important implications for the study of basin–mountain coupling relationships and paleogeographic reconstruction in the southern Ordos Basin and provides a basis for the study of collision evolution of the North and South China Blocks in the Permian.

An in-fiber Mach–Zehnder strain sensor for studying multimode interference of light

Multimode interference of light is an optical interference phenomenon based on waveguides, which has broad applications in optical communication, lasers, and optical fiber sensing. Since optical fiber has become the most widely used optical waveguide in modern society, multimode interference in optical fibers is an ideal candidate for projects in university teaching laboratories. Here, we implement an in-fiber Mach–Zehnder strain sensor-based experiment to study multimode interference in optical fibers. The sensor is fabricated by fusion splicing a piece of thin core fiber between two single mode fibers. One end of the thin core fiber is spliced without a core offset, while the other end is spliced with a core offset. Due to the mode field diameter mismatch and core offset, cladding modes are excited and interfere with the core mode in thin core fiber. Students can observe the sensor fabrication demonstration and perform a strain test with an optical spectrum analyzer. The wavelength spectra captured by the optical spectrum analyzer under different strains are analyzed with the signal processing tools of fast Fourier transform and fast Fourier transform filter. Students then find characteristics of the multimode interference in the sensor from the analysis. The experiment extends undergraduates' knowledge of light interference and is an instructive exercise for them in modern coherence theory.

Effects of ambient temperature and compaction delay time on the performance of cement-stabilised sand–gravel and the determination of allowable construction delay time

ABSTRACT Compaction delay time (t d) refers to the period from the mixing of inorganic binder–stabilised materials to the completion of compaction; this process is affected by ambient temperature (T a). To characterise the effects of T a and t d on the performance of cement-stabilised sand–gravel (CSG) during construction, the reliability of the vertical vibration compaction method (VVCM) is evaluated and the effects of T a and t d on the mechanical strength and freeze–thaw resistance of CSG are investigated. Next, a predictive model for the allowable construction delay time is developed based on a non-loss principle with respect to pavement performance. The results show that the correlation between the mechanical strength of CSG laboratory specimens subjected to VVCM and field core samples can reach ∼90%. Higher T a and longer t d significantly reduce the mechanical strength and freeze-thaw resistance of CSG. Notably, when t d exceeds the initial setting time of cement, the average reductions in compressive strength, splitting strength, and freeze-thaw resistance of CSG are ∼29.3%, 31.3%, and 20.4%, respectively. The allowable construction delay time decreases linearly with increasing T a, showing a correlation of up to 99%. The predictive model can effectively determine the allowable construction delay time at any temperature.

Model for Evaluating Cracking Performance of Asphalt Pavements with Field Aging Based on IDEAL-CT Parameters

This paper develops a simple asphalt pavement field aging model using IDEAL-CT data from 24 field sections from seven field projects that were monitored for 1–4 years each. Field distress surveys were conducted, and field cores were procured and tested in the laboratory approximately every 12 months for each field section. The model predicts IDEAL-CT parameter l75/ m75 (mm2/kN) from the post-peak load–displacement curve. An R2 of 0.91 was achieved when comparing predicted values to measured values indicating that this ratio behaves predictably with field aging. A good correlation is also seen between this ratio and measured field cracking data, making it an excellent candidate for evaluating pavement cracking performance with field aging. This simple model has promising potential use cases including as a tool for mix design, pavement monitoring, and pavement forensics.

Numerical analysis of field aging in asphalt pavements via coupling of diffusion process and kinetics aging model

The asphalt aging model is a crucial module in the Mechanistic-Empirical (ME) pavement design programme for asphalt pavement performance prediction. In this study, an analytical aging model that couples diffusion and kinetics aging model (CDKAM) is improved to analyze and predict the field aging of asphalt pavements. The complex modulus (E*) of field cores was used as the aging property to illustrate the derivation of explicit expressions of time-averaged thermal source term ( TST ¯ ( t ) ) and time-averaged diffusion coefficient ( D ¯ ( t ) ). The value of the material-related parameter (M) in TST ¯ ( t ) model differs among different mixtures, which could assess the mixture’s susceptibility to thermal oxidation. The CDKAM with TST ¯ ( t ) and D ¯ ( t ) was used to predict E* of field aging for asphalt pavements in Texas after 22-month service life. The calibrated CDKAM could reasonably quantify the aging extent over time and the aging gradient over depth for studied asphalt pavements.

Projects as a speciation and aggregation mechanism in transitions: Bridging project management and transitions research in the digitalization of UK architecture, engineering, and construction industry.

Sociotechnical transitions are mostly seen in the literature as processes where actors and technologies in small niches peripheral to an organizational field, accumulate momentum, scale up, aggregate, and eventually bring about large-scale regime change. Foundational examples include the British transition from sailing ships to steamships and the American transition from traditional factories to mass production. Herein lies a paradox, transitions concern large scale system change for example transition to electric cars or renewable energy, but large-scale options for technological change driven by incumbents have received less attention in transitions research. This is an important opportunity for transition research to draw on the literature of project management research on large-scale projects. We bridge transitions research and project management research by exploring speciation and aggregation from both perspectives. We illustrate how this bridge may be instantiated drawing on published research and interviews on six megaprojects that have been instrumental in the digital transformation of UK construction: (i) the Channel Tunnel Rail Link, (ii) Heathrow Terminal 5, (iii) London Olympics, (iv) Crossrail, (v) Thames Tideway and (vi) High Speed Two. The speciation of digital technology seeds the process of aggregation and UK industry transition which is driven by incumbents at the organizational field core and ripples outward to its periphery. This is a reverse process to the one mostly considered in transition research where change initiates in small niches peripheral to an organizational field and propagates until it eventually brings about large-scale change to its core.

Comparative Analysis of Shale Gas Enrichment and High Yield Geological Conditions of Wufeng–Longmaxi Formation and Qiongzhusi Formation in Southern Sichuan Basin

Wufeng–Longmaxi Formation and Qiongzhusi Formation are the significant shale gas exploration strata in China. The former has made a major breakthrough, and the exploration of the latter is restricted. At present, it shows good exploration potential in the Qiongzhusi Formation. Based on the field outcrop and core logging data, the production data from drilled shale gas wells and previous research results combined with the determination of organic matter content, laser Raman spectroscopy of organic matter, X‐ray diffraction experiments, and field emission scanning electron microscopy observations. This study compares the geological conditions and control factors of shale gas enrichment and high yield in the Wufeng–Longmaxi Formation and Qiongzhusi Formation and clarifies the enrichment mode of two sets of shale gas reservoirs. The results show that the organic geochemical conditions of two sets of shale reservoirs are similar, about 0.5%~4.5%. The quartz content of Wufeng–Longmaxi Formation shale (42.5%) is more than that of Qiongzhusi Formation (34.1%~40.2%), and the feldspar content (6.4%) is less than that of Qiongzhusi Formation (20.5~27.3%). The inorganic pores of the Qiongzhusi Formation are more developed than those of the Wufeng–Longmaxi Formation, and the pore size of inorganic pores can reach 100 nm~1 μm. Both of them have good preservation conditions. The enrichment of shale gas in the Wufeng–Longmaxi Formation is controlled by hydrocarbon generation reservoir‐preservation conditions, and the enrichment of shale gas in the Qiongzhusi Formation is mainly controlled by geological structure. It is of great significance to clarify the enrichment control factors of the Qiongzhusi Formation for effectively guiding the continuous exploration and development of the Qiongzhusi Formation. Shale gas exploration in the Qiongzhusi Formation has a very large prospect, which is expected to exceed the Longmaxi Formation.