Instability Processes Research Articles

MACROECONOMIC IMPACTS OF THE CIRCULAR TRANSITION: THE GREEN SWANS OF DECARBONIZATION ON THE PATH TO SUSTAINABILITY

The purpose of the article is to determine the prerequisites for a theoretical rethinking of the problem of price instability and inflation processes as such in the context of a managed green and circular transition as a consequence of the institutional legitimation of climate neutrality on the path to achieving sustainable development. The circular economy, as an important component of the ambitious concept of sustainable development, involves a change in the approach to natural resources, which entails the abandonment of traditional business models and the search for new investment solutions that cannot be fully achieved by attracting private capital. This places great responsibility on governments, which, on the one hand, set ambitious goals (green transition, energy transition, circular transition, sustainable development), and, on the other hand, are not able to respond in a timely manner to the consequences of climate change and to respond to the impacts created by these two factors (institutional pressure and market failures) negative spillover effects. Control of hydrocarbon emissions should be offset by the use of a wide range of green incentives (green quantitative easing policy, green guarantee policy, green subsidy policy) and by providing access to long-term loans as part of responsible government planning. Fiscal, monetary, exchange rate and industrial policies must ensure the sustainability of the green transition. Only in this case can the stability and efficiency of the financial system be guaranteed, as well as the technical re-equipment of the production sector, focused on new technologies, while maintaining its productivity indicators. It has been established that green inflation can occur: as a reaction to irresponsible management (where economic agents actively created such a reality in which environmental degradation and climate problems lead to food, raw material, energy and other crises, which reduces supply, and therefore provokes an increase in prices ); as a reaction to an attempt to implement large-scale projects aimed at decarbonization within a limited time frame (where economic agents and consumers become "victims" of monetary and fiscal policies of governments); as a reaction to the tightening of business standards, for which the end consumer will have to pay (the price of minerals needed for green technologies - from wind turbines and solar panels to electric cars - will require a "green premium" (or "greenium") as due to relatively higher demand on them with limited supply, as well as due to the fact that the extraction of minerals is usually associated with higher environmental costs, which will be "punished" by taxes).

Three-Dimensional Structure of Oceanic Mesoscale Eddies

Mesoscale eddies contribute to the global oceanic energy budget and cascade; they induce substantial mass and heat transport, thus playing a key role in the global climate system. The three-dimensional (3D) structures of mesoscale eddies should be studied in order to quantify their impact. In this paper, mesoscale eddies are reviewed from the perspective of their horizontal and vertical structures, temporal evolution, and fine structures. The universal 3D structure of mesoscale eddies is revealed via observations, and findings show that their tendency to achieve lowest-energy or minimum-dissipation states shapes their lowest-order coherent structure. Recent efforts also push forward to the higher-order structure of eddies: The understanding of horizontal structures is gradually evolving from symmetric to asymmetric, and the vertical structure based on separable variable assumption and vertical mode decomposition should further take the eddy vertical alignment and tilt into account. The temporal evolution of mesoscale eddies’ 3D structure is in a dynamical balance influenced by multiple competitive factors, such as eddies’ self-sustaining ability, background gradient and deformation, and generation of submesoscale fine structures. The submesoscale processes associated with mesoscale eddies have been intensively studied in recent years, and they should be considered as a fine-scale part of the 3D structure of eddies rather than separate instability processes. This review hopes to provide the readers with an enlightening, yet not thorough, review of the development of mesoscale eddies’ structures and brings up potential topics and unresolved difficulties for further research and development.

Оцінювання рівня конкурентоспроможності вітчизняних аграрних підприємств на внутрішньому ринку країни

Competitiveness implies enterprises’ high efficiency and ability to adapt to constantly changing environmental conditions. The high variability of the environment, the difficulty of identifying numerous and closely interacting factors, risks, and dangers, and the entropy of connections and relationships pose urgent tasks for businesses to form competitiveness as a system of measures and technologies to maintain market share, financial stability, and the client base while forming long-term development directions agricultural enterprises. Agricultural production is one of the riskiest types of business activity. Agrarian reforms and the formation of market relations, changes in forms of ownership, and forms of management significantly increase the degree of uncertainty of socio-economic processes in agriculture and, accordingly, increase the impact of risks on agrarian business. The impact of macroeconomic decisions on the activity and competitiveness of each agricultural producer is increasing. Competitiveness is formed, as a rule, at the production stage since the most critical factors that determine the competitiveness of an enterprise are the high quality of its products and the technical level of production. Today, the competitiveness of enterprises is no less important than the efficiency and effectiveness of economic activity, and the problems of achieving and increasing competitiveness are now considered critical issues in managing an organization. Insufficient attention of enterprises to competitiveness issues leads to instability in economic processes and mechanisms, weakening of market positions, and increased dependence on crises. In the conditions of the modern economy and the problems existing in it, the most urgent issue is the improvement of the competitiveness of domestic agricultural enterprises, which is caused by a severe threat to the country’s food security. It was noted that when developing six directions for increasing the competitiveness of agricultural sector products on the domestic and foreign markets, it is necessary to consider the specific features of the state and development of the internal environment due to the complex political situation in the country, which significantly reduced competition within the country. Keywords: competitiveness, agrarian sphere, food security, market conditions, competition.

Влияние кислых сульфатных вод на загрязнение почв террикона в Карабашском рудном районе

Introduction. Technogenic mineral formations are one of the potential sources of pollutants, including heavy metals. On the territory of the Karabash ore district as a result of copper and cobalt ore mining, waste rock heaps are formed and stored. As a result, under the influence of acidic precipitation, oxidation of the surface part of the spoil heap occurs, and the formed products, among which there are heavy metals, are transported by water and aeolian streams to the adjacent landscapes. Methods and materials of research. In the course of work investigated the spoil heap formed by wastes of the mine «Tsentralnaya» in Karabash, Chelyabinsk region. Sampling from the surface of the spoil heap, as well as soil samples with distance from it. The mineralogical composition was determined in the rocks of the heap by X-ray diffraction with Cu-Kα-radiation and crystal mono chromator. Quantitative content of heavy metals was carried out by X-ray spectral method. The reaction of the medium and carbon content of organic matter, as well as the gross content of mobile and water-soluble forms of heavy metals were determined by inversion voltammetry method. According to the results of quantitative analysis of heavy metals in soils, the coefficient of total pollution - Zc was calculated. Research results and discussion. As a result of laboratory analyses, the lithological composition of the main rocks of the spoil heap was determined, which is represented by the main two types: 1) altered quartz-chlorite-sericite schist; 2) highly transformed rocks with no discernible primary mineral composition. The first type contains mainly quartz, feldspars, mica, chlorite and pyrite. The mineralogical composition of the second group is represented by silicates and alumina silicates with gypsum, hydro-arosite and calcium sulphate. Oxidation and limonitization of spoil heap rocks is going on everywhere. In the chemical composition of spoil heaps, predominant are macro-elements Fe, Ca, Mg, K, Na, P, their concentration ranges from 0.13 to 20.38 %, also present in high concentrations of S 0.27-12.31 %, As 0.007-0.11 % and Zn 0.026-0.087 %. All other elements are less than 0.01 %. As a result of rock oxidation such heavy metals as Zn, Cd, Pb, Cu migrate from dumps in the form of sulphates, which is promoted by lowering the pH of the environment. It is revealed that soils located in the depression, on the way of hydro-genic flows, are geochemical barriers for heavy metals. The gross content of heavy metals in soils varies within high limits. Maximum concentrations were recorded in 0-10 cm layer in organogenic and grey humus horizons:Zn - 2890 mg/kg; Cd - 32 mg/kg; Pb - 1270 mg/kg; Cu - 3060 mg/kg. In the vicinity of the spoil heap, relatively high content of mobile forms of heavy metals was recorded inside the soil profile, in the surface layers of soils, with distance from the spoil heap. With distance from the heap, the share of mobile forms decreases in 2 - 2.5 times. The content of water-soluble forms of heavy metals increases with depth in the most remote soils from the spoil heap. In the course of calculations of the total coefficient of soil pollution, it follows that the soils have excessively dangerous and hazardous level of pollution. Conclusion. Thus, in the course of studies of the spoil heap of the mine «Tsentralnaya» of the Karabash ore district, the direct influence of the dumping mass on the contamination of soils of the surrounding areas by migration of heavy metals from the surface of the spoil heap by hydro-genic runoff was established. As a result, rock heterogeneities, less soluble, partially restrain the oxidation rate, forming reducing conditions. The elemental composition of the rocks showed a high content of heavy metals, making this waste rock a source of heavy metals to the surrounding environment. Resume. The instability and heterogeneity of the ongoing geochemical processes in the waste rock mass of the slag heap has been revealed, which leads to leaching of the rock mass slowly over time. Spreading of products of destruction of mineral mass of the spoil heap can be traced in soils up to 800 metres away. As a result of hydro-genic flows from the spoil heap, the soils, have a dangerous and extremely dangerous degree of contamination. As suggestions for practical application and direction of future research, the importance of this work can be noted, which can serve as a foundation for the study of such technogenic mineral formations with a view to their secondary utilization, as well as for determining the most appropriate methods of remediation of contaminated soils.

DEVELOPMENT OF A MATHEMATICAL MODEL OF THE THERMAL FIELD OF AN INTEGRAL STRUCTURE IN THE IMPLEMENTATION OF SENSORS FOR BIOMEDICAL RESEARCH

The paper deals with the implementation of a complex technique for electrothermal modeling of measuring transducers of thermal flow sensors, which combines the synthesis of the impulse temperature relaxation substitution circuit and the method of forming the I-V converters in the mode of their self-heating by the supply current. The issue of assessing the instability of iteration processes in the analysis of I/V measuring converters with negative differential resistance, which is caused by self-heating of these converters, is considered. An express method for determining the limits in which correct electrothermal DC analysis is provided for use in biomedical devices and systems has been developed.

Hyperbranched polymer nanocomposite as a potential shale stabilizer in water-based drilling fluids for improving wellbore stability

Shale hydration has been a frequent and challenging technical problem causing wellbore instability in oil and gas drilling processes. The aim of this study is to design a novel hyperbranched polymer nanocomposite (HBPN) based on a synergistic strategy of physical plugging and chemical inhibition to improve wellbore stability. The inhibitive property of HBPN was comprehensively evaluated through the sodium montmorillonite (Na-MMT) plates immersion test, capillary suction time (CST) test, and shale hot-rolling recovery test. Results implied that HBPN presented better inhibition performance. The shale hydration rate was reduced to 0.03 in the presence of HBPN. Particularly, the shale hot-rolling recovery rate reached 80.54 % at 150 °C and presented long-term shale inhibition durability. It demonstrated excellent plugging performance in the artificial low permeability filter cakes plugging test, reaching a plugging efficiency of 42.45 % with the addition of 2.0 w/v% HBPN. The potential mechanism of action of HBPN was proposed through particle size distribution (PSD) measurement, Zeta (ζ) potential measurement, Fourier transform infrared spectroscopy (FTIR) analysis, X-ray diffraction (XRD) analysis, and scanning electron microscope (SEM) analysis. The coordination of electrostatic interaction and hydrogen bonding impelled a decrease in the ζ potential and interlayer spacing of Na-MMT. Meanwhile, HBPN could embed into formation pores and fractures to establish a tight plugging zone. This approach outlined herein might provide an avenue to strengthen wellbore stability for the drilling industry.

Potential triggers and development processes of submarine landslides in the Xisha Trough Basin, South China Sea

Both submarine landslides and submarine canyons can transfer large amounts of terrigenous quantities from the continental shelf to the deep sea. In some cases, they can have a close relationship to their spatial distribution, formation and evolution. Submarine landslides on the shelf–slope can provide early depressions for submarine canyons, representing the early stage of submarine canyons. The continuous downcutting process during the evolution of submarine canyons can steepen the gradient of the canyon sidewalls, which can lead to the occurrence of submarine landslides. However, the role of submarine canyons in the initiation of slope failure has been overlooked. In this study, high-resolution multibeam bathymetry data, submarine image data and 2-D seismic data were used to investigate two adjacent submarine landslides developed on the northern slope of the Xisha Trough and the spatiotemporal relationship of these landslides to the Central Canyon. We identified a steep downslope between the submarine landslides and the Central Canyon. The Central Canyon formation age was much earlier than those of the submarine landslides. The Central Canyon is filled with modern submarine landslide deposits. The characteristics of the multiple failure scarps indicate retrogressive failure of the submarine landslides. We suggest that the submarine landslides developed on the northern slope of the Xisha Trough Basin have finally been captured by the Central Canyon. We determined that the emptying of sediments at the end of the northern slope of the Xisha Trough Basin caused by the development of the Central Canyon caused the end of the northern slope of the Xisha Trough Basin to lose support, which may have affected the slope stability and could have even played a role in the initiation of submarine landslides. Consequently, the slope area along the Central Canyon may be susceptible to slope instability and slope failure processes.

Study on Instability Change Law of Surrounding Rock of Tunnel Crossing Fault Fracture Zone Based on Cusp Point Mutation Theory

The instability process of surrounding rock is a nonlinear mutation. To truly reflect the nonlinear mutation in the failure of surrounding rock and grasp the opportunity of instability of surrounding rock, it is necessary to study the stability of surrounding rock by combining the existing methods with nonlinear scientific theory. Based on the numerical simulation results of a tunnel project crossing the fault fracture zone, the mutation theory is introduced to study the instability law of surrounding rock during tunnel excavation. The dynamic excavation process of surrounding rock tunnel in fault fracture zone is simulated by the finite difference software FLAC3D. Based on the cusp point mutation theory, the deformation law of each excavation step to the working face under different dip angles, strike angles and thicknesses of fault fracture zone is studied. Combined with the dichotomy method, curve fitting is used to analyze the instability threshold of surrounding rock and predict the opportunity of surrounding rock instability. The results indicate that (1) As the dip angle and strike angle of the fault gradually increase, the settlement of the surrounding rock arch first decreases and then increases, while as the thickness of the fault increases, the vertical displacement of the surrounding rock gradually increases. (2) When the dip angle of the fault is less than 90°, the sudden instability of the surrounding rock is advanced, while when it is greater than 90°, the time for sudden instability is delayed. (3) As the strike angle and thickness of the fault gradually increase, the excavation step for the tunnel to undergo sudden instability is gradually advanced. The research conclusion can provide theoretical guidance and suggestions for similar engineering construction in the future.

Injection-induced fault slip and associated seismicity in the lab: Insights from source mechanisms, local stress states and fault geometry

Probing source mechanisms of natural and induced earthquakes is a powerful tool to unveil associated rupture kinematics. The source processes of failure and slip instability driven by stress loading are affected by fault geometry, but the source ruptures of injection-induced seismicity in relation to fault structures and local stress states remain poorly understood. We have conducted a series of fault reactivation and slip experiments on sandstone samples containing faults with different surface roughness (smooth saw-cut fault and fractured rough fault). We impose progressive fluid injection to induce fault slip, and simultaneously monitor the associated acoustic emission (AE) activity. Using high-resolution AE recordings, we perform full moment tensor inversion of all located AE sources, and investigate the changes of AE source characteristics associated with induced fault slip and their relation to fault roughness. For the complex and rough fault, we observe significant non-double-couple components of AE sources and a high degree of focal mechanism heterogeneity. The temporal changes of AE mechanisms associated with injection-induced fault slip on the smooth fault reveal increasing proportions of double-couple components and decreasing variability of AE focal mechanisms when approaching the onset of slip events. The observed inconsistency between the nodal planes of AE sources and the macroscopic fault plane orientation is attributed to the development of secondary fracture networks surrounding the principal slip surface. We analyze changes in the magnitude-frequency characteristics and source mechanisms of AEs with fault-normal distance, showing that for the smooth (mature) fault, Gutenberg–Richter b-value of on-fault seismicity is lower and focal mechanisms are less heterogeneous, compared to off-fault seismicity. Our results emphasize the important role of roughness-related changes in local fault geometry and associated stress heterogeneity for source mechanisms and rupture kinematics of injection-induced seismicity.

Quantum-inspired distributed policy-value optimization learning with advanced environmental forecasting for real-time generation control in novel power systems

With the increasing weight of wind and photovoltaic power (WPP) in grids, the uncertainty of WPP has an increasing impact on power systems. The access to WPP raises the difficulty of controlling the grid frequency. The existing automatic generation controllers have difficulty in reducing the impact of a high proportion of WPP integration on grid frequency, difficulty in autonomously adjusting power balance in different areas of distributed novel power systems, and slow system operation speed. To address instability, weak adaptability, and slow processing rate caused by large-scale WPP access to novel power systems, this study proposes the quantum-inspired distributed policy-value optimization learning methods for power generation control in distributed systems and adopts the advanced environmental forecasting method into the multi-temporal distance forecasting-distributed Grover policy-value optimization (MF-DGPVO) methods. In this study, the MF-DGPVO methods combine quantum thought with the training process of value optimization and policy optimization to reduce data operations and improve network operation speed. In this study, the MF-DGPVO methods are simulated in the two- and four-area novel power grids. Compared to proportional-integral-derivative, Q learning (QL), state-action-reward-state-action (SARSA), sliding mode control, and fuzzy logic control, the MF-DGPVO methods are more than 30% smaller in frequency deviations and more than 50% smaller in control errors. Besides, the proposed MF-DGPVO approaches obtain greater flexibility than QL and SARSA.

Sliding behaviors of the trapezoidal roof rock block under a lateral dynamic disturbance

The surrounding rock of underground space is always affected by external dynamic disturbance from the side position, such as blasting vibration from a stope at the same level or seismic waves from adjacent strata. A series of laboratory tests, numerical simulations and theoretical analyses were carried out in this study to disclose the sliding mechanism of roof rock blocks under lateral disturbance. Firstly, the experiments on trapezoidal key block under various clamping loads and disturbance were conducted, followed by numerical simulations using the fast Lagrangian analysis of continua (FLAC3D). Then, based on the conventional wave propagation model and the classical shear-slip constitutive model, a theoretical model was proposed to capture the relative displacement between blocks and the sliding displacement of the key block. The results indicate that the sliding displacement of the key block increased linearly with the disturbance energy and decreased exponentially with the clamping load when the key block was disturbed to slide (without instability). Meanwhile, when the key block was disturbed to fall, two types of instability process may appear as immediate type or delayed type. In addition, the propagation of stress waves in the block system exhibited obvious low-velocity and low-frequency characteristics, resulting in the friction reduction effect appearing at the contact interface, which is the essential reason for the sliding of rock blocks. The results can be applied to practical underground engineering and provide valuable guidance for the early detection and prevention of rock-falling disasters.

Study on Instability Process of Slag Landfills: Example of the Subgrade Landslide on Fuxin Nanhuan Road in Liaoning, China

Study on Instability Process of Slag Landfills: Example of the Subgrade Landslide on Fuxin Nanhuan Road in Liaoning, China

Investigation on the disaster mechanism and dynamic evolution of a dump slope using experimental and numerical methods: Case study, Kunyang phosphate mine, China

Dump slope is mainly attributed to the deep excavation of a mine. In the present work, the dump in Kunyang phosphate mine located in Sanjia Village was investigated. The geographic and geologic settings were first studied according to the field investigation. Aiming at the actual dump scenario, a rainfall system was designed to simulate the process of dump instability induced by rainfall. The novelty lies in conducting comprehensive tests on fundamental parameters, including water content, particle size, compactness, and engineering mechanical properties, through analogous simulation experiments. In addition, the SLIDE software was adopted to analyse the dumps in each mining area and subsequently determine the sliding disaster mode of the dumps in Kunyang phosphate mine. The comparative analysis of the dumps in these different mining areas showed that the dump in No. 6 mining area has a greater factor of safety (FS) and better stability (instability will not occur). Secondly, the stability of the dumps in No. 2, No. 3 and No. 4 is better than that in No. 5, but they have not reached the ultimate equilibrium state (instability will not occur). Nevertheless, the FS of the dump in No. 1 mining area approached or even fell below 1. Thus, it is predicted that a small‐scale landslide disaster may have occurred (instability). Moreover, the dynamic evolution characteristics of dump disasters with different accumulation densities were revealed by model device tests. Finally, the obvious tube surge phenomenon before sliding was observed.

Single Cell Whole Genome Measurement of Genomic Heterogeneity and Clonal Evolution in Multiple Myeloma

Background: Sequencing studies have advanced our understanding of the genomic underpinnings of Multiple Myeloma (MM). While whole genome sequencing (WGS) has emerged as a comprehensive approach for profiling the genomic landscape of MM, WGS has limited sensitivity in defining the intrapatient genomic heterogeneity. Single cell RNA approaches can capture phenotypic heterogeneity but fail to recover most of the key genomic drivers. To overcome these historical limitations, we utilized a newer single cell whole genome direct library preparation (scWGS DLP+; Lacks et al. Cell 2019) sequencing technology able to detect early changes and study clonal population dynamics, providing a more precise understanding of the emergence and clinical impact of genomic events during MM evolution. Methods: scWGS DLP+ was applied to CD138 + Plasma Cells (PC) isolated from bone marrow samples of MM patients. Using newly developed computational approaches, we characterized the Single Nucleotide Variants (SNVs), copy number changes and complex Structural Variants (SVs) at a single cell level and use this information to reconstruct the evolutionary histories of each patient's myeloma. Results: We applied DLP to 7 MM patients obtaining 800-1600 single cell whole genomes per patient. All canonical IgH translocations identified by FISH were recovered in the scWGS data. Single cell copy number heterogeneity was observed in all but 1 patient, including heterogeneity affecting known drivers. The number of subclones ranged from 1 to 15, with an average of 6 subclones detected per patient (≥10 cells, ≥5MB distinct segmental difference). This is in striking contrast with bulk WGS where we are usually able to define no more than one or two subclones. Gain of 1q (3 copies) was observed in all patients but was either rare (1-3%, 3 patients) or clonal (>99%, 4 patients), with two clonal 1q patients exhibiting convergent subclonal 1q amplification (>3 copies). Loss of previously gained chromosomes was observed including loss of ancestrally gained chromosome 15 in hypodiploid Patient 2, and sporadic loss of 1q in patients with ubiquitous 1q gain. For 3 of 7 patients, hypodiploidy (HRD) had arisen before the most recent clonal expansion. HRD clones continued to diversify, accruing multiple additional events on HRD chromosomes including large or focal gains, or deletions subsequent to a gain. Interestingly, one case had 1 small hypodiploid clone co-existing with a completely different major clone with 1q and t(14;20) IgH translocation, suggesting the existence of two distinct clonal plasma cell populations (one malignant and one likely bening). Two of the 7 patients harbored both small (<20 cells) whole genome doubled (WGD) subclones, and small numbers of highly aneuploid likely produced by multi-polar cell division post WGD. We explored two patient's evolutionary histories in detail, highlighting the unique resolution of scWGS DLP+ to detect CNV but also SNV, mutational signatures and SVs. Patient 3 exhibited 4 distinct subclones with distant evolutionary origin as evidenced by the relatively small number of shared SNV. APOBEC signature mutations were detected in all 4 subclones suggesting APOBEC mutagenesis was still ongoing across the cell populations in this patient. In Patient 1, a complex SV on chromosome 17 resulted in loss of most of 17q and an amplification of 17q segments. The heterogeneous structure of chromosome 17 across clones suggests a late onset of this complex event and ongoing instability. Chromosome 16 exhibited a pattern of cell specific arm loss likely resulting from telomere loss. Interestingly, a minor clone showed complex amplification of 16p affecting TNFRSF17, suggesting that chromosome 16 is at an earlier stage of a process of instability that starts with cell specific arm loss, and ends with clonal expansion of a complex amplification SV targeting a gene with fitness benefit. Discussion: Applied to Multiple Myeloma, scWGS shows higher clonal heterogeneity than previously described with multiple clones exhibiting diverse genetic alterations. The findings underscore the genomic complexity and dynamic nature of MM, highlighting the need for sensitive techniques like scWGS to capture the full spectrum and chronological order of genomic events.

Geophysical constraints on the deep structure beneath the Xiong'an New Area geothermal field, North China

The region known as the Xiong'an New Area serves as a testing and validation research laboratory for the development and utilization of geothermal energy in China. To better understand the lithospheric structure and associated geothermal features in the region, a comprehensive approach was employed, combining deep seismic reflection and an overlapping magnetotelluric sounding (MT) profile analysis. The analysis reveals arched reflections, coinciding with a relatively high-resistivity anomaly, demonstrating concentric patterns that indicate the presence of lithospheric gneiss domes beneath the Rongcheng and Niutuozhen structural highs. Additionally, the seismic image reveals a marked transparent zone characterised by low-resistivity beneath the Niubei slope. These dome-like features are interpreted as plutons and/or intrusive bodies that were formed by upwelling of the asthenosphere during the early Paleogene era. These relatively deep-rooted plutons are highly likely to be the primary heat sources in this geothermal region. Deep-seated faults beneath the Niubei slope act as channels, allowing the flow of fluids and the transfer of heat from the source to shallower levels. Isotope data supports that the notion that near-surface water flows through a shallow network of fractures, ultimately reaching the geothermal reservoir. The interpreted geometry suggests that the gneiss domes likely resulted from a Rayleigh-Taylor instability process. This process involves diapiric flow induced by density inversion, leading to an upwelling of the asthenosphere. These dynamics, superimposed onto a melted layered structure, generate the distinctive arcuate seismic reflectors found at the core of these domes. Surface geology analysis indicates that the initiation and final emplacement of these domes most likely occurred during the late Mesozoic period.

Impact of pump pulse duration on modulation instability Kerr frequency combs in fiber Fabry-Pérot resonators.

We report an experimental investigation on the impact of the pump pulse duration on the modulation instability process in fiber Fabry-Pérot resonators. We demonstrate that cross-phase modulation between the forward and the backward waves alters significantly the modulation instability process. By varying the pump pulse duration, we show the modification of the modulation instability threshold and frequency. These experimental observations are in excellent agreement with theoretical predictions.

Interaction and breakdown induced by multiple optimal disturbances in hypersonic boundary layer

The present paper finds that the coexistence of multiple primary instability waves may cause a non-trivial nonlinear interaction and breakdown process, which has not been reported before. In the considered Mach 6 flat-plate boundary layer, a global resolvent analysis reports three optimal disturbances (local maxima): a high-frequency planar wave, a low-frequency oblique wave and a stationary streak. For the dominant planar and oblique waves, a parabolised stability equation analysis identifies the initial non-modal transient growth and downstream modal growth. Initiated by these two optimal disturbances jointly, the complete linear and nonlinear instability processes until breakdown to turbulence are shown with direct numerical simulation. Owing to the transient growth, the oblique wave may be more significant than the planar wave in the breakdown. The oblique wave and scales of nonlinear interactions are pronounced in the outer layer, whose significance may not be comprehensively characterised by the wall pressure measurement. Fourier modes characterising the oblique-wave oblique breakdown, the planar-wave fundamental resonance, the planar-wave subharmonic resonance and the combination resonance related to a detuned mode are observed successively. The detuned mode seems to dominate the near-wall dynamics in the late nonlinear stage, characterised by $\varLambda$ -like structures. Meanwhile, the existence of this detuned mode is independent of the initial amplitude ratio and the absolute amplitude of the oblique and planar waves. Weakly nonlinear stability analyses demonstrate that the detuned mode is mainly a consequence of the secondary instability under the combination of planar and oblique primary waves. Wave vector plots reveal the resonant state of multiple triads. Energy budget and amplitude-correction analyses provide a clear physical image of energy transfer.

Transient Stability of Paralleled Virtual Synchronous Generator and Grid-Following Inverter

The majority of inverter-based resources (IBRs) currently operate as grid-following inverters (GFLIs). However, these inverters exhibit certain stability issues when integrated in low-strength areas of the grid. To enhance the grid strength in a GFLI-dominant area, virtual synchronous generators (VSGs) can be installed. If the VSG and the GFLI are investigated as a paralleled system, despite the benefits brought by the VSG, in some cases, the transient angle instability process, caused by a voltage sag, is accelerated, making the whole system more prone to instability. Therefore, this paper aims to study the transient angle stability of a paralleled VSG-GFLI system via investigating the voltage at a common bus between the two IBRs. Subsequently, a stable region of the voltage angles of the two IBRs is determined. Based on this stable region, the stability margin of the paralleled system can be determined and used to quantitatively evaluate the system stability. Moreover, an additional control loop is proposed to improve the transient stability of the paralleled system in this paper. The proposed controller can adaptively reduce the power set-point of the VSG to avoid a complete failure of the VSG even when no stable equilibrium point exists during a voltage sag. The stability investigation and performance evaluation of the proposed method are conducted in PSCAD/EMTDC and experimentally validated.

АНАЛІТИЧНЕ ЗАБЕЗПЕЧЕННЯ ФІНАНСОВОЇ СТРАТЕГІЇ БЕЗПЕКООРІЄНТОВАНОГО УПРАВЛІННЯ

In today's conditions, an integral element of the enterprise management system and a strategic task of financial policy is to determine the level and implementation of measures and actions to ensure financial security. This is substantiated by the rapid globalization and integration processes of business activity, variability and instability of the market space, and force majeure. The priority in developing a financial strategy is its substantiation, which is possible through a comprehensive analysis of financial and economic activity. The purpose of the article is to study the main approaches to strategy development, methods and models of analytical support for the management process of forming a financial security strategy for enterprises. The study used general scientific, special, economic and mathematical methods of cognition of the studied processes and phenomena. Comparison, generalization, analysis, synthesis and systematization are used to understand the strategy, strategic management, and financial security. Structural-logical, tabular, graphical methods, elements of economic and mathematical analysis are used to determine the criteria that influence the formation of a financial strategy for security-oriented management. Analysis is a comprehensive component to substantiate all stages and processes of forming a security-oriented management strategy and implementing a financial security strategy, the main stages of which are: preliminary analysis of the generation of a financial security strategy; analysis at the stage of implementation and implementation of the financial security strategy of enterprises; analysis at the stage of monitoring the implementation of the financial security strategy, the effectiveness of its implementation and adjustment, if necessary. When analyzing and formulating a financial security strategy, it is necessary to use methods of quantitative and qualitative analysis. The most effective are models using economic and mathematical methods and modeling, elements of which are used in the study. The article examines the role of analysis and proposes a model of analytical support for the financial security strategy of enterprises. A systematic hierarchy of indicator ratios has been formed, which are the criteria of financial security and are grouped into groups of indicators: liquidity, financial stability, business activity and profitability. The potential function of an integrated assessment of the level of financial condition of an enterprise made it possible to rank the criteria and prioritize the factors and risks affecting financial security, which minimizes their impact when formulating a strategy in security-oriented management. A detailed analysis of strategic options for ensuring the financial security of the enterprise with criterion justification and a system of measures will be the subject of further investigations.

Single-Photon Level Dispersive Fourier Transform: Ultrasensitive Characterization of Noise-Driven Nonlinear Dynamics.

Dispersive Fourier transform is a characterization technique that allows directly extracting an optical spectrum from a time domain signal, thus providing access to real-time characterization of the signal spectrum. However, these techniques suffer from sensitivity and dynamic range limitations, hampering their use for special applications in, e.g., high-contrast characterizations and sensing. Here, we report on a novel approach to dispersive Fourier transform-based characterization using single-photon detectors. In particular, we experimentally develop this approach by leveraging mutual information analysis for signal processing and hold a performance comparison with standard dispersive Fourier transform detection and statistical tools. We apply the comparison to the analysis of noise-driven nonlinear dynamics arising from well-known modulation instability processes. We demonstrate that with this dispersive Fourier transform approach, mutual information metrics allow for successfully gaining insight into the fluctuations associated with modulation instability-induced spectral broadening, providing qualitatively similar signatures compared to ultrafast photodetector-based dispersive Fourier transform but with improved signal quality and spectral resolution (down to 53 pm). The technique presents an intrinsically unlimited dynamic range and is extremely sensitive, with a sensitivity reaching below the femtowatt (typically 4 orders of magnitude better than ultrafast dispersive Fourier transform detection). We show that this method can not only be implemented to gain insight into noise-driven (spontaneous) frequency conversion processes but also be leveraged to characterize incoherent dynamics seeded by weak coherent optical fields.