Search

This study evaluated the freeze-thaw (F&T) resistance of 3D-printed concrete by analyzing the effects of air-entraining agent (AEA) concentrations, curing methods, and core orientations. Concrete specimens (600 × 600 × 150 mm) with 0%, 0.1%, 0.15%, and 0.2% AEA were cured and tested after 28 days. Cores were drilled horizontally and vertically and then subjected to 360 F&T cycles according to ASTM C666/Procedure B. Microstructural analyses (BET, MIP, SEM, XRD) evaluated changes in pore structure. Results showed 25% of the samples endured 300 cycles without significant damage. F&T damage occurred primarily at interlayer bonds. Horizontal cores showed greater durability due to reduced interlayer gaps. AEA at 0.1% significantly improved F&T resistance and increased dynamic modulus by 15%. BET and MIP analyses showed a 20% increase in average pore size, while SEM confirmed air voids. Optimized AEA levels and curing methods improved the durability of 3D-printed concrete in frost-prone conditions. [ABSTRACT FROM AUTHOR]

Coring is essential for understanding subsurface rock properties and optimizing reservoir characterization. This study explores the application of the Multi-Resolution Graph-Based Clustering (MRGC) method for efficient sample selection in coring programs. Through a detailed analysis of well logs and core data, focusing on mechanical properties like rock strength and elasticity, geomechanical units are identified using the MRGC method. By aligning selection criteria with program objectives and integrating various data sources, the MRGC method optimizes sample selection, offering a comprehensive insight into subsurface geomechanical properties while minimizing core sample requirements. The systematic and targeted sample selection facilitated by the MRGC method ensures that core samples accurately represent the geomechanical characteristics of different field layers. By incorporating petrophysical logs and geomechanical parameters, a model was developed for formations in Gachsaran, Asmari, and Pabdeh-Gorpi-Gadovan. Ultimately, 11 geomechanical units were distinguished from 12 coring wells based on 4 input parameters using the MRGC method. This method improves sample selection accuracy and efficiency, validates geomechanical unit definitions, and offers valuable insights into subsurface geomechanics. [ABSTRACT FROM AUTHOR]

The jackfruit is the largest edible fruit but remains underutilized due to challenges such as sticky latex, labor-intensive peeling/coring, and lack of mechanization. This study developed and evaluated a jackfruit peeling, coring, and cutting machine to enhance processing efficiency. Performance was modeled using response surface methodology (RSM) and artificial neural network (ANN). Three jackfruit sizes (small, medium, and large) and three machine speeds (90, 120, and 150 RPM) were evaluated for peeling time (26.1–50.3 s), peeling efficiency (71.6%–85.3%), coring time (15.5–29.9 s), coring efficiency (74.7%–96.0%), and bulb wastage (6.2%–17.6%). RSM showed high model adequacy (R² ≥ 0.97) and ANN confirmed prediction reliability (R² = 0.81–0.99; mean square error = 4.4–44.9). Increasing fruit size significantly increased peeling and coring times but decreased efficiencies. Machine speeds caused minor variations. Optimized conditions of 120 RPM fruit holder speed and 150 RPM corer speed gave maximum desirability (0.869). The machine had a payback period of 2 years and benefit–cost ratio of 2.32 versus 2.66 for manual peeling/coring. The mechanized jackfruit processing will promote enhanced utilization of this nutritious fruit.Practical applications The mechanized jackfruit peeling-coring-cutting machine developed in this study has significant practical utility. By enabling efficient and rapid processing of jackfruits, the machine can help tap the underutilized potential of this highly nutritious and functionally beneficial fruit. The optimized machine parameters allow jackfruit processing industries to achieve higher throughput with reduced wastage, thereby boosting productivity and profits. Additionally, the mechanization facilitates value-addition by enabling jackfruit utilization in various processed products like chips, flour, jam, etc. Further, the machine helps create livelihood opportunities in jackfruit value chains, as it reduces drudgery and enhances process efficiency as compared to manual methods. The simple fabrication and operation also enable adoption by farmer-producer organizations, self-help groups, and community-based jackfruit processing enterprises. Overall, the mechanized solution provides an impetus for sustainable utilization of jackfruit, while also addressing issues like food loss, nutrition security, income support, and women empowerment. The practical insights on machine performance modeling using response surface methodology and artificial neural network approaches further facilitate quality improvements in equipment design. [ABSTRACT FROM AUTHOR]

With the depletion of shallow resources, the exploration of deep earth resources has become a global strategy. The study of the different patterns in the physical mechanical properties of rocks at different occurrence depths is the basis for exploring deep into the earth, with the core and premise being the acquisition and testing of deep in-situ core specimens. Based on the original idea of deep in-situ condition preserved coring (ICP-Coring) and testing, combined with theoretical modeling, numerical analysis, test platform development, indoor testing and engineering application, the principles and technologies of deep ICP-Coring are developed. This principle and technology consists of five parts: in-situ pressure-preserved coring (IPP-Coring), in-situ substance-preserved coring (ISP-Coring), in-situ temperature-preserved coring (ITP-Coring), in-situ light-preserved coring (ILP-Coring), and in-situ moisture-preserved coring (IMP-Coring). The theory and technology of temperature and pressure reconstruction at different occurrence depths and in different environments are proposed, and prototype trial production was completed by following the principle of displacement and tests based on the in-situ reconstructed environment. The notable advances are as follows: (1) Deep in-situ coring system: A pressure-preserved controller with an ultimate bearing capacity greater than 140 MPa, high-performance (temperature-resistant, pressure-resistant, and low thermally conductive) temperature-preserved materials, an active temperature control system, and high-barrier quality-preserved membrane materials were developed; a deep ICP-Coring capacity calibration platform was independently developed, a deep in-situ coring technology system was developed, and the acquisition of deep in-situ cores was realized. (2) In-situ storage displacement system: Following the dual-circuit hydraulic design idea, a single-drive source push-pull composite grabbing mechanism was designed; the design of the overall structure for the deep in-situ displacement storage system and ultrahigh pressure cabin structure was completed, which could realize docking the coring device and core displacement in the in-situ reconstructed environment. (3) Test analysis system: A noncontact acoustic-electric-magnetic test system was developed under the in-situ reconstructed environment, and the errors between the test results and traditional contact test results were mostly less than 10%; a detachable deep in-situ core true triaxial test system was developed, which could perform loading tests for deep in-situ cores. The relevant technological achievements were successfully applied to the exploration and development of deep resources, such as deep mines, deep-sea natural gas hydrates, and deep oil and gas. The research results provide technical and equipment support for the construction of a theoretical system for deep in-situ rock mechanics, the development of deep earth resources and energy, and the scientific exploration of different layers and occurrence depths (deep and ultradeep) of the Earth.

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A post‐mortem analysis is conducted after potential‐induced degradation (PID) of a commercial copper‐indium‐gallium‐selenide (CIGS) photovoltaic module. After PID, the conversion efficiency of the total module decreased by 62%. Electroluminescence images of the module show that the edges of the modules were much more affected by the PID than the middle part of the module. Coring samples were prepared of the different areas and chemical compositional information of the various areas was combined with electrical characterisation, cell modelling and luminescence data to obtain an overall perspective on the root cause of degradation in these modules during high voltage stress. Consistent with earlier studies on cell level, the module analysis shows the occurrence of alkali migration. From current–voltage modelling, it was concluded that the degradation of the most affected areas is due to an increase in bulk and CdS/CIGS interface defects, likely induced by ion migration. Further degradation on the same samples occurred when they are taken out of the argon‐filled glovebox and stored under ambient conditions. Remarkably, the PID‐degraded areas show stronger degradation when left in ambient atmosphere, as well as a stronger Na redistribution. These new results show that ion migration not only causes the immediate degradation but also strongly affects the longer‐term stability of the cells in ambient atmosphere. This indicates that PID degradation makes CIGS devices more vulnerable to hermeticity problems, which are most prominent at the module edges. [ABSTRACT FROM AUTHOR]

In order to effectively control the water flow from the overburden of the heading roadway, the method of drainage and depressurization combined with intermittent repeated grouting was adopted to transfrom the broken sandstone zone of the heading roadway. Through drilling long distance directional borehole above the roadway, the water-riched area can be drainaged. The layout of grouting boreholes on the plane and vertical was designed, and different grouting orifice devices are used for borehole with different water flow. Long distance directional boreholes were used for drainage grouting, and intermittent circular grouting was used for conventional borehole. The effect of fracture grouting in sandstone was verified by coring test and water inflow observation. It is illustrated by examples that the grouting effect of complete sandstone is poor, while the grouting effect of sandstone with developed fissures is good. The purpose of reducing water inflow of heading roadway and strengthening the broken surrounding rock can be realized by drainage water with borehole to reduce groundwater pressure in local area and sealing the fissures with grouting.

Research at the Selin Farm site in northeastern Honduras examined changing cultural landscapes in a region whose prehistory is poorly understood. Low-impact field methods and radiocarbon dates reveal how this cultural landscape changed in response to shifting priorities among its inhabitants from a.d. 300–1000. We found evidence for rapid accumulation of deposits beginning around a.d. 600, when the site nearly doubled in size over the span of just decades, before retracting again within a few centuries. Although it was caught up in some of the broader social and political changes that began around a.d. 600 throughout northern Honduras and southern Mesoamerica, the longevity of this site suggests stability of the cultural and ecological systems in which it was embedded until the final centuries of occupation. Well-preserved, long-term deposits make Selin Farm an ideal location in which to explore entangled processes of environmental and social change in the little-known small-scale societies of Central America. [ABSTRACT FROM AUTHOR]

Many patients with underlying medical conditions are treated with local anesthetics in dental clinics. Dental local anesthetic cartridges contain the vasoconstrictor adrenaline, which can affect the cardiovascular system. For this reason, the adrenaline in the cartridge (2% lidocaine + 1:80,000 adrenaline) is sometimes diluted in order to avoid hemodynamic changes in these patients. However, at the same time, considerations have to be made for coring. Coring is a process in which a piece of rubber is scraped off when a needle is inserted into a rubber stopper, and the rubber is mixed with the drug solution. Particles generated during the coring process contaminate local anesthetic solutions. In this study, we closely observed the puncture site of a 33G dental needle inside a cartridge to investigate a safe dilution method that considers coring. The puncture site was located within 1.50 ± 0.08 mm (mean ± SD) of the diameter from the center of the rubber stopper of the cartridge head. Punctures were made with a 0.75-mm outer diameter metal needle outside the 1.50-mm diameter range from the center of the rubber stopper to reduce the overlap between puncture sites and minimize the risk of coring. After discarding half of the cartridge, 2% lidocaine without adrenaline was injected by piercing the end of the rubber stopper at the cartridge head with a 22-27G metal needle (outer diameter approximately 0.4-0.7 mm). This method minimizes the risk of rubber displacement and coring while ensuring a safe and effective dilution process. Providing a safer method for adrenaline dilution reduces the risk of coring and contamination in dental anesthetic cartridges., Competing Interests: DECLARATIONS OF INTEREST: The authors declare no conflicts of interest regarding the publication of this letter., (Copyright © 2024 Journal of Dental Anesthesia and Pain Medicine.)

The present study aims to determine the Late Holocene palaeogeographic evolution of the coastal Lihoura plain located at the western part of Pteleos Gulf, in central-eastern Greece. The study area is a low-lying marsh, located at the mouth of an ephemeral stream. In order to determine the evolution of the plain, three cores (max. depth of 6 m) were drilled. Grain size analysis coupled with macro- and micro-palaeontological analyses were performed on sediment samples collected from the cores and six biosedimentary facies were identified corresponding to different depositional palaeoenvironments. The chronostratigraphy of the cores was established by 14C radiocarbon datings on three samples. Furthermore, detailed (at a scale 1:5000) geomorphological mapping was carried out, providing us with valuable information on the palaeogeographic evolution of the area. The results suggest that during the Mid-Holocene, the sea inundated the Lihoura Bay and created a transitional marine-brackish environment. The existence of an elongated (SW-NE) limestone peninsula along with the development of a sand bar shortly after 5027–5462 cal yrs BP, led to the formation of a protected lagoonal environment at the western part of the marshy plain, which at times was influenced by multiple terrestrial inputs induced by fluvial sediment supply. At the northern part of the marshy plain, a very recent high energy marine inundation event has been recorded in the sedimentary stratigraphy. Average rates of relative sea-level rise of 0.78 ± 0.24 mm/yr, 0.94 ± 0.24 mm/yr and 1.45 ± 0.77 mm/yr were estimated for the last 5244.5 ± 217.5 cal yrs BP, 5543 ± 196 cal yrs BP and 1901 ± 200 cal yrs BP respectively, which is in good agreement with previously published sea-level data for the broader area. [ABSTRACT FROM AUTHOR]

Palabiyik et al. (2018, AIChE Journal, 64, 1517-1527) studied the water-based purging of a range of fast moving consumer goods (FMCG) products from pipes wherein the flow initially displaced a core of material then eroded the annulus of residual material on the wall, They reported that the time to clean the pipe fitted a general dependency on wall shear stress when the wall shear stress was expressed as r* (the ratio between the yield stress and wall shear stress), with e > 1. The material is not expected to flow in this case, so erosive removal must involve other mechanisms, such as creep. This work reports a series of experimental and modelling investigations aimed at elucidating these observations. The Theology of a toothpaste, reflecting one of the groups of products studied by Palabiyik et al., was studied. Simple viscoplastic descriptions were unable to capture the observed behaviour. Purging, and particularly the initial breakthrough of water to form a 'core', was investigated using a syringe pump, monitoring the motion of the initial plug of toothpaste and the pressure drop across the plug. We show that a mass transfer model can reproduce the scaling proposed by Palabiyik et al. for laminar flows but a similar scaling did not describe their case where the water flow was turbulent. [ABSTRACT FROM AUTHOR]

The non-homogeneity of in-situ concrete is owing to the intrinsic variability of the material mixture, the workmanship, the construction technology, and the environmental conditions. There is the reason for varying compressive strength of existing reinforced concrete (RC) structures that lead to spatial variabilities of a measurement. In this study, an experimental program on a new existing 25-story RC building has been conducted in order to assess the spatial variability of compressive strength of the laboratory-tested specimens and the on-site cores, coincidentally to find the distribution of these results based on statistical analysis. The spatial variability of compressive strength is identified from 315 cast specimens on-site and 312 specimens collected from the existing structures by the core drilling method. More specifically, the concrete strength variability obtained in RC structural components on-site was investigated through small-scale variability within a single member, large-scale, and global-scale variability between different members made of the same concrete. The casting-in-place cube is the most convenient specimen to ensure that the used concrete complies with the requirements of the design project through the variation of compressive strength in a set of three specimens per batch. According to the analyses presented in this study, there has been a correlation between the spatial variability obtained from cubic specimens and the small-scale spatial variability as found in the core specimens. However, there is a considerable difference between the global and local spatial variability of on-site concrete compressive strength. [ABSTRACT FROM AUTHOR]

The ever‐increasing instalment capacity of Cu (In, Ga)(Se, S)2‐based photovoltaics calls for a better understanding and control of their reliability. In this paper, we show how using a coring‐based method, small samples can be extracted from full size commercial modules, and prepared for lab‐scale analysis. The method is applied to a Cu (In, Ga)(Se, S)2 (CIGS) module where a non‐reversible, propagating ('wormlike') defect has been created in a controlled partial shading experiment. Through current–voltage, photoluminescence and illuminated lock‐in thermography analyses on an undamaged part of the module, the method used is shown to yield fully functional, undamaged active cells, with a photovoltaic conversion efficiency above the full module efficiency. Where the wormlike defects were present, a typical strong shunting behaviour is observed, as well as an increased sulphur content near the edge of the wormtrails. Furthermore, the wormlike defect propagation is shown to be strongly influenced by the present of specific features near the interconnects, which could be the result of manufacturing. These results demonstrate the potential of coring to analyse module failure with all the laboratory tools available. They also shed some light on how wormlike defects, which are a rare but serious hazard for CIGS modules reliability, can form and propagate in commercial, monolithically interconnected modules. [ABSTRACT FROM AUTHOR]

Particles due to fragmentation present a clear risk to the patient. Reported fragmentation rates vary, and an insertion angle at 45°, as opposed to 90°, has been proposed as a mitigation strategy. So, this study evaluated the fragmentation rates induced by single-use hypodermic needles using different angled penetration techniques.

Contemporary cultural geographies have increasingly addressed subterranean and deep spaces through questions of access to earthly materials and the politics of resource extraction. This article engages with these themes through an investigation into the ‘doings’ or practices of seabed access. It does so by following the embodied and material experiences of two human geographers, an artist, a scientific coordinator and a microbiologist, who together undertook a day trip to learn shallow sediment coring in the Wadden Sea mudflats of Northern Germany. Stemming from a research project concerned with the accessibility of the seabed in international waters (how society can access its ‘common heritage’), we examine how taking samples from even the most accessible type of seabed – a shallow coastal mudflat within national waters that is not covered by seawater during low tide – presents a myriad of considerations, challenges and complications. We argue these are vital in examining the cultures of access – the embodied and material limits that define and shape participation in environments in which you and I have rights. These considerations, challenges and complications ranged from physical strength and balance requirements to an understanding of tidal movements, access to simple but specific equipment, appropriate clothing and private transport. We use ethnographic reflections and our photographic engagements to consider sedimentary relations: how we can and do relate to the seabed. [ABSTRACT FROM AUTHOR]

An extensive post‐mortem analysis was conducted on a commercial copper‐(indium‐gallium)‐diselenide (CIGS) photovoltaic module that degraded after exposure to the high voltage stress of a standardized potential induced degradation (PID) test. We employed a custom‐developed coring technique to extract samples from the full‐size field module, which showed degraded and nondegraded areas (regarded as reference) in electroluminescence after the PID test. The resulting solar cell samples were compared based on their electrical properties and sodium profiles using a wide range of laboratory‐based analysis techniques including photoluminescence and lock‐in thermography imaging, current–voltage measurements, and glow discharge optical emission spectroscopy. The samples that were extracted from the degraded areas of the module showed lower photoluminescence intensity and had significantly lower open‐circuit voltage V(oc) and fill factor (FF) values in comparison with reference samples. An increased content of sodium within the absorber layer was also observed for these samples, linking sodium migration to PID. These observations at the module level are consistent with earlier reports on PID‐stressed CIGS cells and mini‐modules. This is to our knowledge the first reported study of a microscopic investigation on a real‐life full‐scale CIGS module after PID. [ABSTRACT FROM AUTHOR]

Modern roadways provide road users with a comfortable and safe ride to their destinations. Due to increasing traffic demands and maximum allowable loads, road authorities should also pay attention to the structural soundness of road pavements while seeking cost-effective and timely maintenance or minor rehabilitation activities. This means that a sustainable pavement preservation strategy is needed that includes an optimal pavement condition assessment to support the appropriate decision-making processes. To address this need, this research study proposes an approach to integrate Non-Destructive Testing (NDT) data and ground truth data to predict the long-term performance of flexible pavements. Appropriate mechanistic models that take into account the nature of Asphalt Concrete (AC) materials are used for the analysis to increase the accuracy of the results when it comes to protecting and extending pavement life. The results indicated that examining viscoelastic behavior for AC appears to be a more conservative approach for the response analysis, as well as the fatigue performance analysis, compared to the most conventional assumptions for linear elastic materials. In accordance with common sense, AC temperature was considered as a critical factor for the related investigation. Overall, it may not be a good and reliable practice to continue the process of pavement management and maintenance decisions based on the approach of only one analysis type. [ABSTRACT FROM AUTHOR]

We show an extensive multimethod geophysical study of focusing on some enigmatic subsurface structures found at Ancient Aigeira (N Peloponnes, Greece) that could be interpreted either as prehistoric chamber tombs or complex weathering patterns of the local marl–conglomerate rock sequences. It turns out that the nonseismic methods do not allow to distinguish between an archaeological and a geological origin of the observed patterns with certainty. In contrast, we demonstrate how shear‐wave seismics and full‐waveform inversion (FWI) can be used in archaeological prospection for distinguishing between these alternative essentially different interpretational models that are not distinguishable through nonseismic prospection data. The example site Aigeira is strategically well located on a hill on the Northern Peloponnese overlooking the Corinthian Gulf and has been inhabited with occupational gaps since Middle Neolithic times until the 12th to early 14th century ce. Magnetics, ground‐penetrating radar (GPR) and electrical resistivity tomography (ERT) reveal a honeycomb‐shaped anomaly pattern that could have been interpreted as a system of prehistoric chamber tombs. The time‐domain SH‐FWI strategy based on a sequential inversion of low‐pass and band‐pass filtered data results in subsurface models for shear‐wave velocity and density that accurately fits the complicated seismic data set. A highly heterogeneous subsurface is revealed that is characterized by linear cracks on a decimetre scale. The seismic FWI results are compared in detail with GPR, ERT and among each other. It turns out that the FWI result is consistent with each of these other geophysical methods but provides a more comprehensive subsurface characterization that it is supported by corings in addition. With the help of the seismic survey, we can reject the interpretation hypothesis of a prehistoric cemetery with chamber tombs and confirm that the enigmatic geophysical patterns represent a geological weathering structure that could be addressed as a reincised fan delta draped by reddish palaeosols. [ABSTRACT FROM AUTHOR]

Probabilistic seismic hazard assessments are primarily based on instrumentally recorded and historically documented earthquakes. For the northern part of the European Alpine Arc, slow crustal deformation results in low earthquake recurrence rates and brings up the necessity to extend our perspective beyond the existing earthquake catalog. The overdeepened basin of Lake Constance (Austria, Germany, and Switzerland), located within the North-Alpine Molasse Basin, is investigated as an ideal (neo-) tectonic archive. The lake is surrounded by major tectonic structures and constrained via the North Alpine Front in the South, the Jura fold-and-thrust belt in the West, and the Hegau-Lake Constance Graben System in the North. Several fault zones reach Lake Constance such as the St. Gallen Fault Zone, a reactivated basement-rooted normal fault, active during several phases from the Permo-Carboniferous to the Mesozoic. To extend the catalog of potentially active fault zones, we compiled an extensive 445 km of multi-channel reflection seismic data in 2017, complementing a moderate-size GI-airgun survey from 2016. The two datasets reveal the complete overdeepened Quaternary trough and its sedimentary infill and the upper part of the Miocene Molasse bedrock. They additionally complement existing seismic vintages that investigated the mass-transport deposit chronology and Mesozoic fault structures. The compilation of 2D seismic data allowed investigating the seismic stratigraphy of the Quaternary infill and its underlying bedrock of Lake Constance, shaped by multiple glaciations. The 2D seismic sections revealed 154 fault indications in the Obersee Basin and 39 fault indications in the Untersee Basin. Their interpretative linkage results in 23 and five major fault planes, respectively. One of the major fault planes, traceable to Cenozoic bedrock, is associated with a prominent offset of the lake bottom on the multibeam bathymetric map. Across this area, high-resolution single channel data was acquired and a transect of five short cores was retrieved displaying significant sediment thickness changes across the seismically mapped fault trace with a surface-rupture related turbidite, all indicating repeated activity of a likely seismogenic strike-slip fault with a normal faulting component. We interpret this fault as northward continuation of the St. Gallen Fault Zone, previously described onshore on 3D seismic data.

In coring operations, core jamming is a permanent concern, taking place when the rock core sample becomes stuck within the inner core barrel, thus preventing further acquisition. This is undesirable in hard formations, for it stops the penetration of the drill bit and results in waste of time and money, especially if it occurs at the beginning of the core run. In unconsolidated formations, there are even more disadvantages, as the jammed sample may rotate along with the core bit, leading the formation to be flushed instead of acquired. This phenomenon is unnoticeable on the surface, and, as a result, the drillers are given no indication of it, thus hindering them from making the decision to pull out of the hole prematurely. Consequently, the characterization of the reservoir rock will be permanently incomplete due to the unrecovered material that was flushed. Despite its importance, the topic of core jamming has not been studied at length. This paper presents an analytical and experimental study in order to contribute for the understanding of jamming processes in unconsolidated or poorly consolidated formations. The study comprises the development of an analytical model, experiments and numerical analysis of the problem. Results are presented and implications for field applications are discussed. [ABSTRACT FROM AUTHOR]

Centre filling of a cylindrical silo results in a peaked grain pile with a high concentration of fines in the bulk core restricting airflow. Fines are also known to have higher mycotoxin levels than whole grain. Coring is recommended to minimise fines and to increase localised airflow through the top grain regions. However, the proportion of coring is not a generalised factor when silo dimensions and fan capacities are considered. Also, the coring proportion used should be minimised to maximise storage capacity and provide good economic returns. A study of sequential coring was conducted using a computational fluid dynamics method to predict the optimised coring volume for a 1000 t silo fitted with 3 kW and 5 kW fans. Each configuration following coring was validated using airflow data measured on the top grain surface of the 12.8 m diameter on-farm silo. Results showed that the model predicted standard errors of 0.0009–0.0024 m s−1 for 16 t, 32 t, 48 t, 80 t, and 158 t coring cases. When fully loaded, around 9% (80 t) of the total mass was required to be unloaded to exhibit the desired airflow in the top-grain region using a 3 kW fan. However, the unloaded mass decreased to 2% (16 t) for the same effect with a 5 kW fan. Thus, a 5 kW fan was recommended as it decreased the proportion of dead zones in the lower bulk region by 65% in a typical 1000 t silo. • Large-scale sequential coring was implemented in a 1000 t On-farm silo. • Optimum storage with coring was evaluated with 3 kW and 5 kW fan power. • CFD model showed negligible prediction error with different coring options. • 9% of fully loaded silo should be cored with 3 kW fan but only 2% with 5 kW fan. • Doubling airflow decreased dead zones by 65% at lower bulk with V-shape duct system. [ABSTRACT FROM AUTHOR]

Pavement analysis encompasses the use of different assumptions for material assessment that can in turn induce variations in the predicted pavement critical strains and affect the outcome of pavement evaluation. This research deals with the incorporation of mechanistic principles into asphalt pavements structural assessment, considering variable mechanical behavior (elastic and viscoelastic) for the Asphalt Concrete (AC) materials. A field experiment along a new asphalt pavement structure was performed including Non-Destructive Testing (NDT) and coring. The study focused on the tensile strains within the AC layers that usually trigger rehabilitation actions. For strain calculations, the standard practice of Multi-Layered Elastic Theory (MLET) and the rheological Huet-Sayegh model were both implemented into the analysis. Results indicated statistically significant discrepancies between elastic and viscoelastic calculations that may become considerable in terms of decision-making. Thus, pavement engineers should not proceed with the decision-making process based solely on a unique approach. In addition, the issue of performing a new pavement's evaluation based on the design assumptions was discussed. A substantial material differentiation pinpointed the need to extract cores in order to perform viscoelastic material characterization. Moving forward with a regression analysis, a practical approach was developed for viscoelastic strains prediction from NDT data in order to avoid extensive coring. Overall, the implementation of the framework at a new structure is grounded on that the methodology followed for pavement evaluation throughout its service life can predefine the way of decision-making in terms of consistently interpreting the analysis output and assessing future maintenance needs. [ABSTRACT FROM AUTHOR]

Shale gas loss by leakage directly affects the accurate measurement of shale gas content during drilling and coring. To accurately calculate shale gas loss, in combination with the actual situation of the shale coring, considering the influence factors of the main occurrence state of shale gas (free state and adsorption state), by means of treating the three stages of the shale well core removal, ground exposure, and water bath heating and desorption as a process of desorption that changes with confining pressure, an indoor shale gas loss simulation experiment method was independently designed to determine shale gas loss. Two sets of samples with large differences in physical properties in eastern Sichuan were selected for the shale gas loss simulation experiment. We proposed to use the error reduction rate of shale gas loss (the percentage of the difference between the shale gas loss obtained by the simulation experiment method and the rate obtained by the improved USBM method and curve fitting method and the amount of gas loss of core injected) to verify the accuracy of the simulation experiment method. The results show that compared with the improved USBM method, the average error reduction rate of cores by the experiment method were: 8.64%. Compared with the curve fitting method, the average error reduction rate of cores by the experiment method were 25.11%, which proved that the shale gas loss simulation experiment method had higher accuracy.

Modern roadways provide road users with a comfortable and safe ride to their destinations. Due to increasing traffic demands and maximum allowable loads, road authorities should also pay attention to the structural soundness of road pavements while seeking cost-effective and timely maintenance or minor rehabilitation activities. This means that a sustainable pavement preservation strategy is needed that includes an optimal pavement condition assessment to support the appropriate decision-making processes. To address this need, this research study proposes an approach to integrate Non-Destructive Testing (NDT) data and ground truth data to predict the long-term performance of flexible pavements. Appropriate mechanistic models that take into account the nature of Asphalt Concrete (AC) materials are used for the analysis to increase the accuracy of the results when it comes to protecting and extending pavement life. The results indicated that examining viscoelastic behavior for AC appears to be a more conservative approach for the response analysis, as well as the fatigue performance analysis, compared to the most conventional assumptions for linear elastic materials. In accordance with common sense, AC temperature was considered as a critical factor for the related investigation. Overall, it may not be a good and reliable practice to continue the process of pavement management and maintenance decisions based on the approach of only one analysis type.

Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Single and multielement archaeological geochemistry has been applied to research and rescue projects for many decades to enhance our understanding of the past use of space. Often applied on one contextual plane, this ignores the complex palimpsest resulting from past occupation and soil processes. Furthermore, many important sites are now heavily truncated by plowing, leaving little more than negative features below the homogenized topsoil. These challenges require new approaches to archaeological geochemistry to gather information before these sites are lost to modern land use. The research presented here applied coring as a sampling method on a truncated site, the sample locations guided by high‐resolution ground‐penetrating radar data and excavation, before using portable X‐ray fluorescence directly on the core samples to understand the phase by phase composition of the deposits and thus past human occupation. The results suggest that even in truncated and secondary contexts, such as the case study of the Viking Age trade settlement of Heimdalsjordet, Norway, archaeological geochemistry can give insight into the chronological and spatial development of the site, and is especially relevant for detecting nonferrous metalworking activity. [ABSTRACT FROM AUTHOR]

The continuous direct extrusion is an economic and efficient process to manufacture high-quality aluminium profiles. However, because of multiple billets processing, transient defects (coring and charge welds) can be generated affecting portions of the profiles and deteriorating their mechanical properties. In case of structural applications, the reliable prediction of the onset and extend of these portions is therefore mandatory in order to be scrapped by the commercialized length. In this context, the present work has been aimed at examining the dynamic evolution of the coring and charge weld defects in the direct extrusion of an industrial solid profile. Both experimental and numerical activities have been performed and results evaluated in terms of coring and charge welds defect evolution achieving a good agreement for both phenomena. Results have been also compared with the outcomes of the analytical models available in literature. For the charge weld extension, the analytical model returned a poor predictably while a very good match with numerical data was obtained for the coring defect. [ABSTRACT FROM AUTHOR]

Fine roots and above‐ground litterfall play a pivotal role in carbon dynamics in forests. Nonetheless, direct estimation of stocks of fine roots remains methodologically challenging. Models are thus widely used to estimate these stocks and help elucidate drivers of fine root growth and turnover, at a range of scales.We updated a database of fine root biomass, necromass and production derived from 454 plots across European forests. We then compared fine root biomass and production to estimates obtained from 19 different models. Typical input variables used for the models included climate, net primary production, foliage and above‐ground biomass, leaf area index (LAI), latitude and/or land cover type. We tested whether performance could be improved by fitting new multiple regression models, and explored effects of species composition and sampling method on estimated fine root biomass.Average fine root biomass was 332 g/m2, and necromass 379 g/m2, for European forests where the average fine root production was 250 g m−2 year−1. Carbon fraction in fine roots averaged 48.4%, and was 1.5% greater in broadleaved species than conifers.Available models were poor predictors of fine root biomass and production. The best performing models assumed proportionality between above‐ and below‐ground compartments, and used remotely sensed LAI or foliage biomass as key inputs. Model performance was improved by use of multiple regressions, which revealed consistently greater biomass and production in stands dominated by broadleaved species as well as in mixed stands even after accounting for climatic differences.Synthesis. We assessed the potential of existing models to estimate fine root biomass and production in European forests. We show that recalibration reduces by about 40% errors in estimates currently produced by the best available models, and increases three‐fold explained variation. Our results underline the quantitative significance of fine roots (live and dead) to the global carbon cycle. [ABSTRACT FROM AUTHOR]

Temperature is the primary factor affecting the law of coal gas desorption. When the core method is used to measure the coal seam gas content (CSGS), the temperature of the coal core sample (CCS) will increase. The heat generated by the core bit cutting and rubbing the coal during coring is transferred to the CCS through the core tube, resulting in the temperature rising of the CCS. Because the CCS entering the core tube during coring is a dynamic process, the temperature of CCS is difficult to measure. To solve this problem, the temperatures of the core tube wall during coring in the Jiulishan coal mine (JLS), Guhanshan coal mine (GHS) and Zhaogu coal mine (ZG) at the core depth of 20 m were measured by the self-designed temperature measuring device. The thermodynamic models of the core bit and the core tube during coring were established. The reliability of the model was verified by comparing the numerical simulation results with the field measurement results. The verified model was used to predict the temperature changes of the core tube wall during coring in different strength coal seams and different core depths. The results show that the temperature change of the core tube wall was divided into a slowly temperature rising stage Ⅰ, a fast temperature rising stage Ⅱ and a slowly temperature rising and slowly temperature falling stage Ⅲ, which correspond to the process of pushing the core tube, drilling the CCS and early stage and later stage of withdrawing the core tube, respectively. The maximum temperature of the core tube wall appears in the first 3 min of withdrawing the core tube, and increases with the core depth increasing. The temperature of the measuring point at the end of drilling the CCS and the maximum temperature during coring linearly increase with the core depth. The temperature heating rate of the core tube is negatively linear, with the coal seam strength during pushing the core tube wall process. However, the temperature heating rate of the core tube wall is positively linear with the coal seam strength during drilling the CCS process. This study can provide a basis for further research on the dynamic distribution characteristics of temperature in the CCS during coring, which is of profound significance to calculate the gas loss amount and CSGC.

Maintenance interventions and rehabilitation actions in airfield pavements are time-consuming and adversely affect pavements’ serviceability (i.e., airport closures), with a profound impact on the airport economics. Once a pavement is constructed, a robust asset management prerequisites systematic and accurate knowledge of pavement condition throughout its service life. Evaluating a pavement’s structural capacity in the field involves the integration of multiple Non-Destructive Testing (NDT) systems, with the Falling Weight Deflectometer (FWD) being the most indicative NDT system for pavement evaluation. The purpose of the present study is to develop a methodology for the assessment of airfield concrete pavements. A new and non-trafficked Jointed Plain Concrete Pavement (JPCP), facing early-life cracks shortly after a runway’s expansion activities, was utilized for the investigation. Multiple types of data collected in the field, including deflections, load transfer efficiency at joints and cracks, concrete thickness through coring as well as data retrieved in the laboratory (concrete’s flexural strength), helped to define the pavement’s performance and assess its damage potential. Overall, the integration of such data can provide the related airport authorities the necessary information in order to make a rational asset management and enhance the efficiency of airfield infrastructures. The methodology is applicable for both new and in-service pavements.