Hasil untuk "Dynamic and structural geology"

Xuerui Wang, Guangyu Ren, Tianhong Dai et al.

Goal-conditioned reinforcement learning has shown considerable potential in robotic manipulation; however, existing approaches remain limited by their reliance on prioritizing collected experience, resulting in suboptimal performance across diverse tasks. Inspired by human learning behaviors, we propose a more comprehensive learning paradigm, ACDC, which integrates multidimensional Adaptive Curriculum (AC) Planning with Dynamic Contrastive (DC) Control to guide the agent along a well-designed learning trajectory. More specifically, at the planning level, the AC component schedules the learning curriculum by dynamically balancing diversity-driven exploration and quality-driven exploitation based on the agent's success rate and training progress. At the control level, the DC component implements the curriculum plan through norm-constrained contrastive learning, enabling magnitude-guided experience selection aligned with the current curriculum focus. Extensive experiments on challenging robotic manipulation tasks demonstrate that ACDC consistently outperforms the state-of-the-art baselines in both sample efficiency and final task success rate.

Tanguy Phulpin, Rym Boulahbel, Hafaliana Randrianjanaka et al.

Inductive Power Transfer (IPT) is evolving fast in many domains, but its efficiency, its extensive resource requirements, and its cost remain crucial problems for its development. Although the inverter is mainly responsible for its cost and material consumption, a considerable quantity of conductors is required for the coupling realization. Therefore, A drastic cost reduction is possible when comparing the traditional most efficient copper Litz wire with aluminum conductors for a similar volume and a lighter embedded system. However, alternative ribbon wire solutions are also characterized and seem promising as substitutes for such applications. First, standard electrical efficiency is evaluated for all cases, before the price and weight. To complement the results and as the alternative couplers imply different materials and production processes, a Life Cycle Assessment is performed. A comparison is carried out on copper and aluminum litz wires and copper and aluminum ribbons. Results demonstrate the promising interest in industrial application of such study, furthermore for systems requiring many couplers as Dynamic IPT (DIPT).

Yunlong Xue, Yinghan Gao, Xiaobo Peng

Carbonate fracture–cavity reservoirs are significant oil and gas reservoirs globally, and their efficient development is influenced by the connectivity between fracture–cavity units within the reservoir. These reservoirs primarily consist of large caves, dissolution holes, and natural fractures, which serve as the primary storage and flow spaces. The S91 unit of the Tarim Oilfield is a karstic fracture–cavity reservoir with shallow coverage. It exhibits significant heterogeneity in the fracture–cavity reservoirs and presents complex connectivity between the fracture–cavity bodies. The integration of static and dynamic data, including geology, well logging, seismic, and production dynamics, resulted in the development of a set of static and dynamic connectivity evaluation processes designed for highly heterogeneous fracture–cavity reservoirs. Methods include using structural gradient tensors and stratigraphic continuity attributes to delineate the boundaries of caves and holes; performing RGB fusion analysis of coherence, curvature, and variance attributes to characterize large-scale fault development features; applying ant-tracking algorithms and fracture simulation techniques to identify the distribution and density characteristics of fracture zones; utilizing 3D visualization technology to describe the spatial relationship between fracture–cavity units and large-scale faults and fracture development zones; and combining dynamic data to verify interwell connectivity. This process will provide a key geological basis for optimizing well network deployment, improving water and gas injection efficiency, predicting residual oil distribution, and formulating adjustment measures, thereby improving the development efficiency of such complex reservoirs.

Levin, Lev Yu., Semin, Mikhail A., Vshivkov, Aleksei N. et al.

The article involves the study of the freezing process of medium-grained sand saturated with aqueous NaCl solutions of various concentrations (0–104 g/l). The purpose of the study is to determine the influence of NaCl concentration on heat and mass transfer processes. Freezing was initiated from one end of the sample; the temperature field was recorded by eight thermocouples, while the moisture distribution was determined by weighing followed by drying. The results confirmed a linear decrease in the freezing point of pore water with increasing NaCl concentration, down to –7°C. It was found that in all tests, moisture redistribution occurred with its accumulation near the freezing front. In non-saline samples this effect was most pronounced, which can be attributed to the combined influence of thermodiffusion and phase pressure differences at the water–ice interface. With increasing salinity, this effect weakened, and the contrast in moisture content between frozen and unfrozen zones decreased. The obtained time-space distributions of temperature and moisture provide a basis for parameterizing mathematical models of heat and mass transfer in frozen media, as well as serve as a starting point for further studies of freezing processes in saline soils.

Can Zhang, Hongme Guo, Dongming Wang et al.

We conducted a rapid seismic intensity assessment of a M 6.8 earthquake in Dingri, Xizang, using a ground motion parameter attenuation model based on the shortest fault distance combined with either an empirical equation for the surface rupture length or data on the aftershocks that occurred within 1.5 ​hr after the earthquake. The assessment showed that the empirical equation for the relationship between the surface rupture length and magnitude established by Wells et al. yielded a surface rupture length that was closer to the actual value, while the seismic intensity determined using a combination of the ground motion parameter attenuation model and the empirical equation for the surface rupture length was relatively in line with the intensity from the actual investigation. This study also demonstrated that manual intervention and screening are needed for aftershocks within 1.5 ​hr after the earthquake if this information is to be employed in the intensity assessment. In addition, if the death assessment model does not consider the seismic vulnerability of local buildings, significant errors can occur in practice. Nevertheless, the disaster assessment results were obtained within 5 ​min after the earthquake, thus providing important data support for the government emergency command and decision-making associated with the emergency rescue response.

Neha, Tarunpreet Bhatia

Intrusion Detection Systems (IDS) are critical components in safeguarding 5G/6G networks from both internal and external cyber threats. While traditional IDS approaches rely heavily on signature-based methods, they struggle to detect novel and evolving attacks. This paper presents an advanced IDS framework that leverages adversarial training and dynamic neural networks in 5G/6G networks to enhance network security by providing robust, real-time threat detection and response capabilities. Unlike conventional models, which require costly retraining to update knowledge, the proposed framework integrates incremental learning algorithms, reducing the need for frequent retraining. Adversarial training is used to fortify the IDS against poisoned data. By using fewer features and incorporating statistical properties, the system can efficiently detect potential threats. Extensive evaluations using the NSL- KDD dataset demonstrate that the proposed approach provides better accuracy of 82.33% for multiclass classification of various network attacks while resisting dataset poisoning. This research highlights the potential of adversarial-trained, dynamic neural networks for building resilient IDS solutions.

Erik Lørup

The overall goal of this thesis is to investigate the connection between the dynamics and structure of molecular glass formers, by testing different scaling laws for both. The inspiration for this work is the Isomorph theory because it predicts a connection between structure and dynamics. The fundamental prediction of the Isomorph Theory is that there exist lines in the phase diagram where both structure and dynamics are invariant when presented in reduced units. The prediction of constant dynamics has been tested and confirmed experimentally several times, but the structural prediction has never been confirmed experimentally. In this thesis, we have investigated the structural prediction for liquids where the prediction of constant dynamics has been shown experimentally.

Tao Bai, Ying Yu, Peng Li et al.

The Wyoming CarbonSAFE project is located at the Powder River Basin (PRB) in northeast Wyoming, which aims to safely store over 50 million metric tons of CO 2 for a period of 30 years at three stacked reservoirs including Lakota sandstone, Hulett sandstone, and Upper Minnelusa formation. Site-specific characterization data, including well logs, seismic data, core data, and field tests, are integrated into the dynamic model for initializing reservoir pressure and regional stress state and estimating petrophysical and rock mechanical properties. An integrated reservoir simulation and geomechanical modeling are then performed to estimate the well injectivity, storage capacity, surface displacement, integrity of reservoir and caprock, and fault stability. The presented workflow demonstrates how the stacked storage approach helps with large-scale geologic carbon sequestration within structurally complex reservoirs

Rongzhe Zhang, Jiarong Zhang, Tonglin Li et al.

The magnetotelluric (MT) inversion technology is crucial for quantitatively interpreting deep mineral resources, especially when combined with rock physics information, enhancing accuracy in assessing underground structural parameters and spatial distribution. However, the traditional fuzzy c-means (FCMs) clustering-constrained inversion method requires prior rock physics information for each geological unit, limiting their application scope. We propose a guided FCMs (GFCMs) clustering-constrained inversion method based on adaptive virtual rock physics information, referred to as XG-FCM-constrained MT inversion. This method breaks free from the constraints of traditional methods by not relying on prior rock physics information. In terms of extracting virtual rock physics information, we employ a local density clustering algorithm to dynamically extract resistivity model information from MT inversion iterations, automatically determining the number of clusters and cluster centers. Regarding the inversion strategy, we construct an integrated objective function that combines data fitting, smoothing constraint, and GFCM constraint, implementing a two-stage iterative solution strategy of “smoothing first, clustering second.” Model testing demonstrates that compared to traditional smoothing-constrained MT inversion, the XG-FCM-constrained method achieves a significant improvement in the resolution of resistivity model reconstruction, clearly delineating the boundaries of underground anomalies. Even in situations where rock physics information is insufficient or absent, this method can effectively reconstruct high-quality underground resistivity models, reducing the dependence on complete prior information. The application of actual field data further highlights the advantages of the XG-FCM-constrained MT inversion method, providing robust support for accurately delineating geological unit boundaries and precisely identifying potential ore deposit target areas.

K. Kotríková, Ľ. Lovásová, M. Kurejová Stojkovová et al.

<p>In recent years, the impacts of climate change have become increasingly apparent; Slovakia has witnessed a rise in extreme weather conditions caused by climate change. To address these challenges, we analyze and prepare documents focused on monitoring and issuing drought warnings. These documents, including Slovakia's water resource balance, serve as fundamental materials for water management planning. The water resource balance assesses the relationship between water demands and available resources in the past year, identifying areas and times where water demands exceed supply. Additionally, our analysis provides a detailed map of surface and groundwater abstractions across Slovakia, categorizing total and individual abstractions by sector (e.g., public water supply systems, agriculture, and industry). We present surface and groundwater abstraction averages for the period of the last decade 2013–2022, along with its spatial distribution in Slovak districts. This comprehensive approach enables us to better understand and manage our water resources effectively.</p>

I. Farahbakhsh, C. T. Bauch, M. Anand

<p>Mathematical models that couple human behavior to environmental processes can offer valuable insights into how human behavior affects various types of ecological, climate, and epidemiological systems. This review focuses on human drivers of tipping events in coupled human–environment systems where changes to the human system can abruptly lead to desirable or undesirable new human–environment states. We use snowball sampling from relevant search terms to review the modeling of social processes – such as social norms and rates of social change – that are shown to drive tipping events, finding that many affect the coupled system depending on the system type and initial conditions. For example, tipping points can manifest very differently in human extraction versus human emission systems. Some potential interventions, such as reducing costs associated with sustainable behavior, have intuitive results. However, their beneficial outcomes via less obvious tipping events are highlighted. Of the models reviewed, we found that greater structural complexity can be associated with increased potential for tipping events. We review generic and state-of-the-art techniques in early warning signals of tipping events and identify significant opportunities to utilize digital social data to look for such signals. We conclude with an outline of challenges and promising future directions specific to furthering our understanding and informing policy that promotes sustainability within coupled human–environment systems. </p> <p><strong>Non-technical summary.</strong> Mathematical models that include interactions between humans and the environment can provide valuable information to further our understanding of tipping points. Many social processes such as social norms and rates of social change can affect these tipping points in ways that are often specific to the system being modeled. Higher complexity of social structure can increase the likelihood of these transitions. We discuss how data are used to predict tipping events across many coupled systems.</p>

Guy Salomon, Theron Finley, Edwin Nissen et al.

The advent of sub-meter resolution topographic surveying has revolutionized active fault mapping. Light detection and ranging (lidar) collected using crewed airborne laser scanning (ALS) can provide ground coverage of entire fault systems but is expensive, while Structure-from-Motion (SfM) photogrammetry from uncrewed aerial vehicles (UAVs) is popular for mapping smaller sites but cannot image beneath vegetation. Here, we present a new UAV laser scanning (ULS) system which overcomes these limitations to survey fault-related topography cost-effectively, at desirable spatial resolutions, and even beneath dense vegetation. In describing our system, data acquisition and processing workflows, we provide a practical guide for other researchers interested in developing their own ULS capabilities. We showcase ULS data collected over faults from a variety of terrain and vegetation types across the Canadian Cordillera and compare them to conventional ALS and SfM data. Due to the lower, slower UAV flights, ULS offers improved ground return density (~260 points/m2 for the capture of a paleoseismic trenching site and ~10–72 points/m2 for larger, multi-kilometer fault surveys) over conventional ALS (~3–9 points/m2) as well as better vegetation penetration than both ALS and SfM. The resulting ~20–50 cm-resolution ULS terrain models reveal fine-scale tectonic landforms that would otherwise be challenging to image.

Ali Mohaghar, Mohammad Hasan Maleki, mohammad khakzadeh

Before the coronavirus pandemic, higher education centers and companies paid little attention to e-learning. The outbreak of the pandemic and the development of digital technologies have caused companies to pay much attention to e-learning. Therefore, companies are looking for the effective use of e-learning tools. The current research seeks to provide a framework to improve the effectiveness of the e-learning system in Hyper Famili chain stores. The current research is applied in terms of orientation and has a quantitative nature in terms of methodology. This study used two Fuzzy Delphi and Marcos methods for data analysis. The theoretical population of the research was managers, experts, and consultants in the field of education in Hyper Famili. Sampling was done as a judgment based on the expertise of experts in eLearning. The sample size was equal to 10 people. Interviews and questionnaires were used to collect data. The questionnaires used in this research were expert and priority questionnaires. In the first stage, 32 factors were obtained through literature review and interviews with eLearning experts. As a next step, these factors were screened by the distribution of expert questionnaires and the fuzzy Delphi method. Ten factors were selected for final prioritization with Marcos. The screened factors were prioritized by distributing priority questionnaires and Marcos. According to the scores, the most important factors have been found. Practical research proposals were developed based on the most prioritized factors. Some practical suggestions of the research were holding a training workshop on the benefits and applications of e-learning for senior managers, considering the appropriate budget for purchasing and preparing the necessary infrastructure in the field of e-learning, preparing strategic and operational documents based on future developments of new technologies in Iran and the world and the use of instructors with electronic teaching skills.

Mohammed Sultan Alshayef, A. P. Pradeepkumar

M. Ben-Asher, F. Magnin, S. Westermann et al.

<p>Water takes part in most physical processes that shape mountainous periglacial landscapes and initiation of mass-wasting processes. An observed increase in rockfall activity in high mountain regions was previously linked to permafrost degradation, and water that infiltrates into rock fractures is one of the likely drivers of processes related to thawing and destabilization. However, there is very little knowledge of the quantity and timing of water availability for infiltration into steep rock slopes. This knowledge gap originates from the complex meteorological, hydrological, and thermal processes that control snowmelt, as well as challenging access and data acquisition in extreme alpine environments. Here we use field measurements and numerical modeling to simulate the energy balance and hydrological fluxes on a steep high-elevation permafrost-affected rock slope at Aiguille du Midi (3842 m a.s.l, France), in the Mont Blanc massif. Our results provide new information about water balance at the surface of steep rock slopes. Model results suggest that only <span class="inline-formula">∼</span> 25 % of the snowfall accumulates in our study site; the remaining <span class="inline-formula">∼</span> 75 % is likely transported downslope by wind and gravity. The snowpack thickness was found to decrease with surface slopes between 40 and 70<span class="inline-formula">^∘</span>. We found that among all water fluxes, sublimation is the main process of snowpack mass loss at our study site. Snowmelt occurs between spring and late summer, but most of it may not reach the rock surface due to refreezing and the formation of an impermeable ice layer at the base of the snowpack, which was observed at the field site. The annual snowmelt that is available for infiltration (i.e., effective snowmelt) is highly variable in the simulated years 1959–2021, and its onset occurs mostly between May and August and ends before October. By applying the model to a range of altitudes, we show that effective snowmelt is the main source of water for infiltration above 3600 m a.s.l.; below, direct rainfall on the snow-free surface is the dominant source. This change from snowmelt- to rainfall-dominated water input leads to an abrupt, nonlinear increase in water availability at altitudes below 3600 m a.s.l and may point to higher sensitivity of permafrost-affected rock slopes to climate change at these altitudes.</p>

Leilei Shi, Donghong Xia

Based on the structural viscoelastic boundary theory, considering the geological changes of the soil layer and depth of tunnel crossing, the dynamic time course analysis is carried out for the defective lined tube sheet structure under non-uniform seismic excitation, to obtain the force and deformation law of the whole tunnel structure as well as the defective section. Analyze the dynamic response of shield tunnel structure under non-consistent seismic excitation under the influence of tube sheet misalignment factors, summarize the intrinsic mechanism of the dynamic response of defective tunnel tube lining structure, identify the phenomena affecting lining junction damage, and refine the seismic safety evaluation method of defective lining structure.

Maxime Vassaux

Collagen type I is well-known for its outstanding mechanical properties which it inherits from its hierarchical structure. Collagen type I fibrils may be viewed as an heterogeneous material made of protein, macromolecules (such as glycosaminoglycans and proteoglycans) and water. Water content modulates the properties of these heterofibrils. Yet, the properties of water and the fine interactions of water with the protein constituent of these nanocomposites have only received limited attention. Here, we propose to model collagen type I fibrils as an hydrated structure made of tropocollagen molecules assembled in a microfibril crystal. We perform large-scale all-atom molecular dynamics simulations of the hydration of collagen fibrils beyond the onset of disassembly. We found that the structural and dynamic properties of water vary strongly with the level of hydration of the microfibril. More importantly, we found that the properties vary spatially within the 67 nm D-spacing periodic structure. Alteration of the structural and dynamical properties of the collagen microfibril occur first in the gap region. Overall, we identify that the change in the role of water molecules from glue to lubricant between tropocollagen molecules arises around 100% hydration while the microfibril begins to disassemble beyond 130% water content. Our findings are supported by a decrease in hydrogen bonding, recovery of bulk water properties and amorphisation of the tropocollagen molecules packing. Our simulations reveal the structure and dynamics of hydrated collagen fibrils with unprecedented spatial resolution from physiological conditions to disassembly. Beyond the process of self-assembly and the emergence of mechanical properties of collagen type I fibrils, our results may also provide new insights in mineralization of collagen fibrils.

William Baldwin, Xia Liang, Johan Klarbring et al.

Metal halide perovskites are multifunctional semiconductors with tunable structures and properties. They are highly dynamic crystals with complex octahedral tilting patterns and strongly anharmonic atomic behaviour. In the higher temperature, higher symmetry phases of these materials, several complex structural features have been observed. The local structure can differ greatly from the average structure and there is evidence that dynamic two-dimensional structures of correlated octahedral motion form. An understanding of the underlying complex atomistic dynamics is, however, still lacking. In this work, the local structure of the inorganic perovskite CsPbI$_3$ is investigated using a new machine learning force field based on the atomic cluster expansion framework. Through analysis of the temporal and spatial correlation observed during large-scale simulations, we reveal that the low frequency motion of octahedral tilts implies a double-well effective potential landscape, even well into the cubic phase. Moreover, dynamic local regions of lower symmetry are present within both higher symmetry phases. These regions are planar and we report the length and timescales of the motion. Finally, we investigate and visualise the spatial arrangement of these features and their interactions, providing a comprehensive picture of local structure in the higher symmetry phases.

Alberto Toffano, J. Russo, M. Rescigno et al.

We model, via classical molecular dynamics simulations, the plastic phase of ice VII across a wide range of the phase diagram of interest for planetary investigations. Although structural and dynamical properties of plastic ice VII are mostly independent on the thermodynamic conditions, the hydrogen bond network (HBN) acquires a diverse spectrum of topologies distinctly different from that of liquid water and of ice VII simulated at the same pressure. We observe that the HBN topology of plastic ice carries some degree of similarity with the crystal phase, stronger at thermodynamic conditions proximal to ice VII, and gradually lessening when approaching the liquid state. Our results enrich our understanding of the properties of water at high pressure and high temperature and may help in rationalizing the geology of water-rich planets.

Yue-Hong Feng, Ming Mei, Guojing Zhang

For unipolar hydrodynamic model of semiconductor device represented by Euler-Poisson equations, when the doping profile is supersonic, the existence of steady transonic shock solutions and C-smooth steady transonic solutions for Euler-Poisson Equations were established in [27] and [41], respectively. In this paper we further study the nonlinear structural stability and the linear dynamic instability of these steady transonic solutions. When the C^1-smooth transonic steady-states pass through the sonic line, they produce singularities for the system, and cause some essential difficulty in the proof of structural stability. For any relaxation time, by means of elaborate singularity analysis, we first investigate the structural stability of the C^1-smooth transonic steady-states, once the perturbations of the initial data and the doping profiles are small enough. Moreover, when the relaxation time is large enough, under the condition that the electric field is positive at the shock location, we prove that the transonic shock steady-states are structurally stable with respect to small perturbations of the supersonic doping profile. Furthermore, we show the linearly dynamic instability for these transonic shock steady-states provided that the electric field is suitable negative. The proofs for the structural stability results are based on singularity analysis, a monotonicity argument on the shock position and the downstream density, and the stability analysis of supersonic and subsonic solutions. The linear dynamic instability of the steady transonic shock for Euler-Poisson equations can be transformed to the ill-posedness of a free boundary problem for the Klein-Gordon equation. By using a nontrivial transformation and the shooting method, we prove that the linearized problem has a transonic shock solution with exponential growths. These results enrich and develop the existing studies.