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This study presents a new method to generate random fiber arrangements in a representative volume element model, which remains applicable at high fiber volume fractions. First of all, the fibers are arranged regularly to ensure accurate fiber volume fraction. Afterwards, disturbances are applied to all fibers to generate random arrangements. The image recognition technique and statistical analysis are used to quantitatively evaluate the randomness of the disturbed fiber arrangement. Eventually, the high efficiency of the method is verified by analyzing the consumption time of modeling, and its validity is also confirmed by comparing the calculated results with the tested results. [ABSTRACT FROM AUTHOR]

This paper presents a robust controller design for a discrete linear system, dealing with internal and external disturbances. The main focus is to reduce chattering, minimize undesirable oscillations, and enhance robustness against disturbances using a new discrete sliding mode control. The novel approach involves replacing the classical Gao's reaching law with a fractional order reaching law based on the Grunwald–Letnikov definition, leading to advantages like a simplified algorithm and improved performance against disturbances. The performances of the suggested method are evaluated through two simulation examples. [ABSTRACT FROM AUTHOR]

Social‐ecological memory (SEM) may be a key source of resilience in social‐ecological systems (SES), allowing for renewal and reorganisation after disturbances. This study provides an overview of the genesis and evolution of the SEM concept, its research trends and gaps, and its potential applicability to geographical thought. Combining systematic review and bibliometric analysis, we collected 219 records published in the last two decades, which were reduced to 87 relevant records after applying the inclusion/exclusion criterion. The results indicate that interest in SEM research is growing, but wide acceptance and concordance around terminology are still lagging. The concept has substantially evolved and expanded over the last decade but remains mostly abstract and conceptual. Research has focused predominantly on European countries, rural contexts, and westernised societies, identified multiple disturbances and ecosystem services as driving the maintenance and evolution of SEM, and highlighted an unequal interest between social and ecological memory carriers. Our review underlines the strong pertinence of the SEM concept for the study and management of social‐ecological systems, which would benefit from the development of application strategies and tools. In the future, researchers should seek to expand the idea of social‐ecological memory into an applied field having clearer links and boundaries with more established concepts important in geography, among them traditional ecological knowledge. [ABSTRACT FROM AUTHOR]

Arc devices are among the receivers with the highest power connected to power systems. Due to dynamic load changes, these receivers generate a number of disturbances that affect the quality of electric power. The most important disturbances include voltage fluctuations. It is also worth mentioning the asymmetry and deformation of the supply voltage curve. This article discusses the mutual interaction of receivers operating in parallel, operating stably, and devices with dynamic current consumption. Calculations based on model tests and the results of parameters characterizing the quality of energy, which were recorded in the line supplying the steelworks, are presented. The power supply conditions (power of the short-circuit network) were assessed to influence the degree of suppression of voltage fluctuations by loads with stable current consumption. [ABSTRACT FROM AUTHOR]

Summary: Quadrotor transportation systems have been widely utilized in both commercial and civilian fields. However, challenges arise due to the variable payload mass and unpredictable wind disturbances during cargo transport, potentially leading to excessive payload swinging and system instability. To tackle this issue, this article proposes an adaptive sliding mode control approach that concurrently achieves trajectory tracking for the quadrotor and mitigates payload swinging. In the outer loop subsystem, the quadrotor dynamics model is partitioned into two components that is, actuated and underactuated components. Sliding surfaces are designed based on this divided system model, and two adaptive laws are designed to compensate for payload mass uncertainty and unknown wind disturbances. The system's asymptotic stability is assured through the application of the Lyapunov theorem. In the inner loop subsystem, a disturbance rejection controller is formulated. Comparative simulation results conclusively demonstrate the outstanding performance of the proposed method in terms of trajectory tracking and robustness. [ABSTRACT FROM AUTHOR]

This work presents a methodology for controlling a quadrotor vehicle in both regulation and trajectory tracking tasks when the system is affected by endogenous and exogenous disturbances. In the proposed approach, the quadrotor is driven by a second-order variable-gain sliding mode controller (VG-SMC), which includes a state-dependent variable-gain that allows enhancing the controller performance against disturbances. Besides, the proposed controller achieves finite-time convergence of the position and orientation error signals and their time derivatives. The performance of the closed-loop system is assessed by comparing it with a standard sliding mode controller whose control objective is to track two optimal smooth reference signals. The comparison between both controllers considers the undisturbed and the perturbed cases. Numerical simulations and experimental results demonstrate that the proposed VG-SMC controller provides better overall closed-loop results than those obtained by a fixed-gain sliding mode controller, despite the presence of disturbances. [ABSTRACT FROM AUTHOR]

Elucidating the climate feedback due to forest cover loss is critical for a comprehensive understanding of the role of forests in mitigating climate change. Current research studies predominantly focus on the impacts of permanent forest conversion, often overlooking the effects of recurrent disturbances such as fire and harvest. This study addresses this gap by examining the impact of forest cover loss caused by two distinct drivers in China over the period 2003–2020. Our analysis revealed that fire‐induced forest cover loss accounted for approximately 10% of total forest cover loss in China. The immediate (i.e., 1 year after disturbance) changes in land surface temperature (ΔLST) due to fire were higher (ΔLST = 0.11°C, interquartile range (IQR): [−0.02°C–0.23°C]) compared to those caused by harvest (ΔLST = 0.04°C, IQR: [−0.01°C–0.09°C]). This finding highlights the immediate warming effect of fire‐induced forest cover loss, was about triple as large as that caused by harvest. Our analysis also found that the warming effect post‐fire gradually lessened but still maintained approximately 0.02°C 5 years later. Change in evapotranspiration is a primary factor influencing surface temperature changes following forest disturbances. Our study provides comprehensive insights into the differential and persistent effects of LST responses to fire and harvest, underscoring the importance of understanding the climate feedback from forest dynamics from different drivers. Plain Language Summary: This study quantified the biophysical effects attributable to recurrent forest cover loss caused by fire and harvest using a space‐for‐time approach. Previous reports have primarily explored the temperature impacts of either permanent or gradual disturbances. However, the gaps of biophysical effects from recurrent disturbances should not be overlooked. In this paper, we quantified forest cover loss due to fire and harvest and compared surface temperature following these changes. We then identified the dominant biophysical processes governing the LST response to forest cover loss. What we find is a much more pronounced warming effect and a longer recovery period with increasing proportions of fire‐affected areas than that under harvest, with ET being the primary factor driving these LST changes. Our comparable results from different recurrent disturbances provide valuable insights for future research. Key Points: Surface temperature warming effects resulting from forest cover loss under different recurrent disturbances should be widely acknowledgedTemperature feedbacks caused by fire‐induced forest cover loss was higher than those caused by harvestEvapotranspiration is a primary factor influencing surface temperature changes following forest disturbances in temperate forests in China [ABSTRACT FROM AUTHOR]

Restoration involves the recovery and repair of environments because environmental damage is not always irreversible, and communities are not infinitely resilient to such harm. When restoration projects are applied to nature, either directly or indirectly these may take the form of ecological, forestry or hydrological restoration, for example. In the current scenario of global climate change and increasing intensity of disturbances the importance of restoration in all types of ecosystems in order to adapt to the new conditions (so called prestoration) is evident. Whatever the objective of the restoration initiative, there is a lack of consensus as regards common indicators to evaluate the success or failure of the different initiatives implemented. In this study, we have carried out an extensive meta-analysis review of scientific papers aiming to evaluate the outcomes of restoration projects. We have done a review and selected 95 studies implemented in Europe. We explored the main pre-restoration land cover in which restoration initiatives have been implemented, the main causes of degradation, the objective of the restoration action and the indicators selected to analyze the success or failure of the action. We identified a total of 84 indicators in the analyzed papers and compared with the ones proposed for forest in the recent Nature Restoration Law. The analysis revealed five indicators commonly used for the evaluation of restoration initiatives (abundance, coverage, density, Ellenberg indicator, and richness), even where the initial objective has not yet been achieved. Our findings underscore both the benefits and challenges associated with a specific set of harmonized indicators for evaluating the success or failure of restoration initiatives. [ABSTRACT FROM AUTHOR]

Questions: Maintaining forest species diversity, regenerative function and ecosystem resilience begins with successful seedling establishment. Despite their critical role, seedlings face the highest mortality risks among plant life‐history stages. Our research aims to answer the following questions: In a tropical forest disturbed by typhoons, what is the median survival time for seedlings, to what extent do light levels contribute to mortality risks and what are the crucial mortality risks across seedling age groups? Location: A tropical mountain zonal foothill evergreen broad‐leaved forest in Nanjenshan Nature Reserve, Taiwan, frequently visited by typhoons. Methods: We investigated woody seedlings in 75 quadrats (each 1 m × 1 m) every 3 months from October 2009 to January 2018, spanning 8.3 years with 34 censuses. We used the Kaplan–Meier method to estimate seedlings' median survival time and Generalized Linear Models to identify mortality risk factors for all seedlings and those that persisted beyond the median survival time. Results: The median survival time for all seedlings was 0.5 years, ranging from 0.25 years for shade‐intolerant species to 1.25 years for shade‐tolerant species. Seedlings germinated in high‐light microhabitats and high conspecific seedling density exhibited higher mortality probabilities, regardless of age. Conclusions: This study reveals the short survival time and key mortality risks of seedlings in a typhoon‐disturbed forest. The negative impact of light levels on seedling survival highlights the potential consequences of increased light levels resulting from typhoon disturbances in the study region. [ABSTRACT FROM AUTHOR]

This paper studies state observation for a heterogeneous quasilinear traffic flow system with disturbances at the inlet of a considered road section. Based on the backstepping method, an observer is designed for the quasilinear traffic flow system with only the boundary measurements at the inlet of the considered road section. The observer is constructed by duplicating the quasilinear system and adding the output injection terms to the partial differential equations and boundary conditions. Making use of the backstepping transformation, the injection gains of the observer system are derived by the computation of kernel equations, which are obtained by mapping the error system into an integral input-to-state stable target system. The applicability of the observer for the design of an output feedback controller stabilizing the quasilinear system is discussed. Finally the assumptions of the design of the observer are numerically checked on a realistic congested traffic scenario. [ABSTRACT FROM AUTHOR]

Anthropogenic and environmental stressors damage the structure and function of coral reefs. Monitoring data is important because it allows scientists to detect changes that are of interest for managers and policymakers. This study aims to examine the benthic component (abiotic and biotic) and determine coral life-history composition at different reef types (atoll and fringing) and regions (Wangi-Wangi and Kaledupa) in the Wakatobi National Park (WNP), Southeast Sulawesi, Indonesia. We examine the data using life-history traits in regard to group species and describe community composition. Kaledupa fringing reef had 46% hard coral cover, which was the highest hard coral cover in our study. There was no significant difference in hard coral and soft coral cover between regions within WNP. Reef type, however, showed significant differences in hard coral and soft coral cover, as well as sand, rubble, and rock. The families Acroporidae and Poritidae were the most dominant across all sites and reef types in WNP. The life-history classification showed competitive and stress-tolerant coral covers were greatest on fringing reefs. Our findings provide information regarding coral reef benthic community composition and distribution across regions and reef types in WNP, which can aid in coral reef conservation. [ABSTRACT FROM AUTHOR]

Resilience is commonly addressed when dealing with the sustainable planning and management of social–ecological systems, but we lack a unified framework for its quantitative assessment and application. We present an operational resilience framework (ORF) based on recognizing and relating several elements: system variables (e.g., ecosystem services), disturbances and stressors acting at given spatiotemporal scales, a reference state, and metrics comparing the observed system variables to the reference state. These elements fit into a rationale aimed at identifying resilience predictors suitable to be managed and co-drivers which describe non-manageable context, reflecting the mechanisms involved in resilience. By a systematic search of the presence of the ORF concepts in 453 empirical studies assessing resilience, we corroborate that ORF can be applied to studies on forest social–ecological systems. This literature survey shows that ORF elements are commonly recognized, although the logical narrative relating them is not always explicit, particularly in socioeconomic-focused studies. We advocate that the proposed ORF allows to standardize the terminology and to frame and measure resilience, allowing sounder comparisons and better-supported recommendations for the improvement of resilience in social–ecological systems, particularly in forest systems. [ABSTRACT FROM AUTHOR]

Conventional L1 adaptive controller utilizes high adaptation gain to quickly adapt time varying uncertainties and disturbances. However, it contaminates the control signal with high frequency components. To eliminate this high frequency signal, it uses a low pass filter with fixed structure. Yet, the main problem with this fixed structured filter is that it may cancel the estimated values of uncertainties and disturbances along with the high frequencies. To overcome this problem, in this research work, an adaptive fuzzy low pass filter is proposed in place of the fixed structured filter of the L1 adaptive controller. In this proposed research work, the filter changes its structure according to the time varying uncertainties and disturbances. Hence, the contributory part of this work is that the proposed adaptive fuzzy filter efficiently cancels out high frequency components without nullifying the estimated values of uncertainties and disturbances from the control signal. The stability of the proposed adaptive fuzzy filter-based L1 adaptive controller is guaranteed analytically. The proposed method is employed on an electromechanical actuator, viz., DC motor experimental setup to validate its effectiveness. Adequate cancellation of high frequency signal incurs smooth control signal which in turn provides lower control energy. [ABSTRACT FROM AUTHOR]

Phyllanthus emblica is a well-known medicinal and non-timber forest product species, widely distributed in the Indian subcontinent. Multiple disturbances like intensive fruit harvest, the spread of invasive species such as Lantana camara and Taxillus tomentosus, and other anthropogenic disturbances threaten population viability by altering ecological and genetic processes. Studying the genetic diversity and population structure of species harvested intensively and subjected to anthropogenic disturbances is crucial for evaluating their ability to survive under future environmental changes and for establishing conservation strategies. The genetic diversity and population structure of twelve populations of P. emblica that are harvested across three protected areas of the Western Ghats, the world’s most densely populated biodiversity hotspot was evaluated. Three hundred sixty samples were genotyped with nine simple sequence repeat markers. The changes in genetic diversity and genetic structure were assessed between generations by analyzing adults, seedlings, and juvenile samples. Despite intensive harvesting, the results found high genetic diversity in all the populations (mean/pop: Ho = 0.626; Hs = 0.722). However, genetic differentiation was significant between the study regions as well as between adult and seedling populations. The study also indicated a clear clustering of the twelve populations into three distinct genetic clusters. Neighbor-joining tree and hierarchical clustering analysis also showed the same pattern. The genetic data from the study provide information on how local disturbances including harvesting affect the population's genetic diversity and structure, which can provide a basis for implementing programs for conserving and sustainable utilization of P. emblica genetic resources in the future. [ABSTRACT FROM AUTHOR]

Southeastern Patagonia's (49° S) post‐glacial history inferred from high Andean lake sediments provides new insights regarding Late Pleistocene and Holocene vegetation dynamics at the eastern margin of the Southern Patagonian Icefield. The fossil records of pollen, charcoal and geochemical data from tephra layers from Laguna Chiquita and Laguna Gemelas Este were analysed to reveal past landscape dynamics related to vegetation changes, fire and volcanic events from ca. 15 200 cal a bp to the present. Nothofagus forest expanded over shrubland communities sometime between 15 200 and 4600 cal a bp, along with at least three disturbance sources related to the volcanic eruptions of Lautaro, Aguilera and Hudson, important local fire episodes, and neoglacial advances. Major charcoal deposition reveals moderate fire activity during the Late Pleistocene related to an open landscape characterised by a grass/shrub steppe. Local glacier advances may have affected the Laguna Gemelas Este sedimentation. Tephra deposition events do not correlate to vegetation changes inferred from the Laguna Gemelas Este and Laguna Chiquita pollen records. Late Holocene eastern Andean forest changes and fire activity at 49° S match other southern palaeoenvironmental records (50–52° S) suggesting that changes in the Southern Westerly Wind latitudinal position and intensity drove major palaeovegetation and fire dynamics before the European settlement. In the last centuries, fire and vegetation changes have been closely related to an increase in local ignition sources and the introduction of alien species. [ABSTRACT FROM AUTHOR]

The robust control problem of permanent magnet synchronous motor (PMSM) is discussed in this paper. Both iron loss and voltage saturation are considered in the analysis process in order to close to the actual projects. A controller design method, which is called the Hamiltonian-based method, is proposed for the PMSM control system. The responses of each current component and speed are analyzed when load torque disturbance exists. The proposed controller enables the closed-loop system to have robust performance criteria without violating saturation. It is worth noting that a more general truncation-inequality technique is used to deal with saturation, which reduces the conservatism of parameter selection. In addition, the corresponding results are given for two special cases. When there is no saturation and no load torque disturbance, the system is asymptotically stable at the equilibrium point. Simulation results and experimental study show that the proposed method has good load disturbance suppression ability and can ensure the robust performance of the PMSM in EV driving systems. [ABSTRACT FROM AUTHOR]

Hemeroby and naturalness are indicators of ecosystem health and can be used to assess the state of aquatic macrophyte communities in floodplain landscapes under anthropogenic pressure. This article verifies the hypothesis that hemeroby and naturalness are distinguished by specific spatial patterns. Hemeroby is sensitive to changes in the level of anthropogenic pressure under conditions of a high level of ecosystem transformation. Naturalness is capable of responding to environmental disturbances of both natural and anthropogenic origin and is sensitive to changes in the state of ecosystems as they approach natural conditions. The variability of the naturalness of aquatic macrophyte communities does not depend on the direction of spatial patterns. Accounting for the directionality of spatial patterns provides a better explanation for the small-scale component of community hemeroby variability. [ABSTRACT FROM AUTHOR]

This paper investigates the one-bit function perturbation (OBFP) impact on the robust set stability of Boolean networks with disturbances (DBNs). Firstly, the dynamics of these networks are converted into the algebraic forms utilizing the semi-tensor product (STP) method. Secondly, OBFP's impact on the robust set stability of DBNs is divided into two situations. Then, by constructing a state set and defining an index vector, several necessary and sufficient conditions to guarantee that a DBN under OBFP can stay robust set stable unchanged are provided. Finally, a biological example is proposed to demonstrate the effectiveness of the obtained theoretical results. [ABSTRACT FROM AUTHOR]

Questions: Herbivory and fire are the main disturbance drivers in open ecosystems. The aim of this study was to evaluate the effects of fire, cattle grazing, and their interaction on structural traits and the Normalized Difference Vegetation Index (NDVI) of the tussock grass Saccharum angustifolium, and its temporal dynamics in a subhumid grassland. Location: Grasslands of the Eastern Hills, Uruguay. Methods: We set three blocks (four plots of 300 m2 each) in a homogeneous grazed area dominated by S. angustifolium within a protected area. Each block presented the combinations that emerged from the two levels of cattle grazing (grazed/ungrazed) and burning (burned/unburned) factors. The experimental burning was carried out in the spring. Clump volume, number of flowering culms, NDVI of S. angustifolium, and soil variables were measured for 2 years. Results: Burning efficiency (plant biomass burned of the total available) was 82%, burn intensity ranged from 178–610 kW m−1, and the soil temperature increased 40% compared with pre‐fire measurements. The volume of S. angustifolium clumps decreased with fire, and the difference between burned–unburned plots decreased with time. The burned–ungrazed treatment increased the number of S. angustifolium flowering culms. NDVI of S. angustifolium clumps increased 50% with fire, and then decreased with time. Soil temperature was higher in burned treatments, and moisture was higher in unburned treatments on some dates. Bulk density, for the 0–5‐cm depth, was 9% higher in burned than in unburned plots irrespective of grazing. Conclusions: Our results provide new data in favor of the management practice carried out by ranchers in Uruguayan grasslands dominated by S. angustifolium. Our data complement the evidence that a fire–grazing interaction can maintain grasslands in different phases of a stable state. Our results constitute a useful contribution for the managers/authorities of the protected area, and can be extrapolated to other tussock grass‐dominated grassland areas. [ABSTRACT FROM AUTHOR]

Questions: Marine rocky outcrops are model systems of community assembly under harsh conditions. The prevailing environmental conditions that determine a coast–inland gradient of stress and disturbance impose a strong environmental filter on community assembly. However, the Atlantic rocky outcrops of Uruguay challenge this assumption as they exhibit high plant diversity at small spatial scales. We investigated this study system to answer: (1) which environmental factors determine diversity at the local scale; (2) and how does the regional pool influence species composition along the coast–inland gradient? Methods: We analyzed the local and regional determinants of plant community assembly in four rocky sites along the Uruguayan coast. Through a random sampling approach stratified by distance to the coast, we recorded species occurrences and microenvironmental conditions. Observed taxa were assigned into different species assemblages according to their typical vegetation type. Generalized Linear Model (GLM)–Poisson regression, quantile regressions and hierarchical cluster analyses were used to identify the factors underlying local richness and the spatial vegetation structure. Results: Nine different vegetation types generate a mass effect that enhances local diversity. Unexpectedly, 56% of the species are from non‐marine environments — e.g. grasslands or hydrophilous herblands. Species assemblages were spatially clustered, with a turnover of these clusters along the coast–inland gradient. Elevation, distance to the coast and vegetation cover promoted richness, likely due to an attenuation of marine filters. Meanwhile, substrate availability reduced richness, likely due to competitive exclusion as a result of more resources and homogeneous microenvironmental conditions. Conclusions: The high local diversity along the marine rocky outcrops of Uruguay is best explained by a functionally diverse regional species pool, which interacts with local heterogeneity, and by conditions that enhance or attenuate the effect of marine stress. Effective conservation and management strategies are key to minimize the detrimental effects of urbanization, fragmentation, and non‐native plant invasions on these diverse habitats. [ABSTRACT FROM AUTHOR]

Summary: The problem of interval parity relations design for systems described by linear and nonlinear models under the external disturbances is considered. The problem is solved based on the reduced‐order model of the original system. The relations allowing designing interval parity relations insensitive or having minimal sensitivity to the disturbances are obtained. The obtained interval parity relations are used to solve the problem of fault diagnosis. Theoretical results are illustrated by example. [ABSTRACT FROM AUTHOR]

Tropical ecosystems face escalating global change. These shifts can disrupt tropical forests' carbon (C) balance and impact root dynamics. Since roots perform essential functions such as resource acquisition and tissue protection, root responses can inform about the strategies and vulnerabilities of ecosystems facing present and future global changes. However, root trait dynamics are poorly understood, especially in tropical ecosystems. We analyzed existing research on tropical root responses to key global change drivers: warming, drought, flooding, cyclones, nitrogen (N) deposition, elevated (e) CO2, and fires. Based on tree species‐ and community‐level literature, we obtained 266 root trait observations from 93 studies across 24 tropical countries. We found differences in the proportion of root responsiveness to global change among different global change drivers but not among root categories. In particular, we observed that tropical root systems responded to warming and eCO2 by increasing root biomass in species‐scale studies. Drought increased the root: shoot ratio with no change in root biomass, indicating a decline in aboveground biomass. Despite N deposition being the most studied global change driver, it had some of the most variable effects on root characteristics, with few predictable responses. Episodic disturbances such as cyclones, fires, and flooding consistently resulted in a change in root trait expressions, with cyclones and fires increasing root production, potentially due to shifts in plant community and nutrient inputs, while flooding changed plant regulatory metabolisms due to low oxygen conditions. The data available to date clearly show that tropical forest root characteristics and dynamics are responding to global change, although in ways that are not always predictable. This synthesis indicates the need for replicated studies across root characteristics at species and community scales under different global change factors. [ABSTRACT FROM AUTHOR]

Climate change, changes in the natural environment, changing markets, price volatility, etc. pose tension and threats to the future of European Union farms. The uncertain future of family farms requires farm resilience—the ability to survive, adapt, and grow in the face of turbulent change. The limited resilience of family farms has become an important concern for rural and agricultural policy. The main goal of this work is to identify disturbances affecting Lithuanian family farms, assess their influence, investigate the general resilience of Lithuanian family farms, propose measures to reduce the vulnerability of farms, and increase the general resilience and sustainability. We used a combination of qualitative and quantitative research methods to conduct the research. Survey research was conducted using a semi-structured expert interview in which various types of variables were collected. The survey questionnaire, consisting of 38 groups of questions, was sent by email to 500 randomly selected family farmers in January 2024 and collected in the same month. The statistical analysis of the data from the 205 duly filled-out questionnaires was carried out using correlation analysis. In this article, we apply the concept of general resilience of the family farm in the direction of robustness, adaptability, and transformability. We identify the main factors influencing the general resilience of the family farm and study the main attributes of the resilience of family farms. We find some links between family farm characteristics, vulnerability factors, and general resilience capabilities, and we make several proposals to increase family farms' resilience. The obtained results prove that higher education, larger farm sizes, higher agricultural sales, and employment of permanent workers are associated with better resilience. Furthermore, increasing environmentally friendly practices positively impacts resilience. Older farms and farmers, longer durations of farming activity, and risk-averse behaviors tend to decrease resilience. Due to local and global circumstances, economic and social changes have occurred very quickly in recent years, so the results obtained in the study may not be valid in the long term. Similar surveys after several years will be necessary to study the resilience of Lithuanian farms, including deeper economic analyses that evaluate factors such as price sensitivity, the level of farm debt, and market access. [ABSTRACT FROM AUTHOR]

There are growing concerns about the effect of solar flares on the ionosphere, mainly due to possible deterioration or damage to our communication and navigation satellite systems. On 3 July 2021, and 28 October 2021, there were solar flares (SFs) classified as X1.59 and X1.0, respectively. These two SFs were the only ones of X‐class that occurred during the last low solar activity (LSA:2018–2021). Data from magnetometers and Global Positioning System (GPS)—Total Electron Content (TEC) are used to investigate the spatial‐temporal electrodynamics of the ionosphere from pole‐to‐pole in the American sector. Employing ∆H and vertical TEC, along with the ROT (rate of change of VTEC) parameter. Rapidly ∆H disturbances closely follow the X‐ray variation and the ∆H valleys and peaks are well‐synchronized during the SFs, indicating that they are linked. Major disturbances in the ∆H are noticed in the mid‐low‐equatorial latitudes. However, minor disturbances were seen at high latitudes. Also, |ROT| is a good indicator of the electron density changes during the SFs, especially when the X‐ray intensity rises to the peak. Plain Language Summary: There are growing concerns about the effect of solar flares on the ionosphere, mainly due to possible deterioration or damage to our communication and navigation satellite systems. This kind of space weather event known as solar flare, releases energy in the form of radiation in the entire electromagnetic spectrum. However, the UV, EUV, and X‐ray radiation burst penetrates deeper into the Earth's atmosphere and is absorbed in the D and E regions (lower ionosphere) and F‐region. In this investigation the ionospheric disturbances are investigated, from pole‐to‐pole, using a magnetometer and GPS‐TEC networks. Key Points: The primary objective of this paper is to investigate the ionospheric response to solar flares across the entire latitudinal rangeThe ∆H exhibited synchronized peaks and valleys, during SF. The ROT is the most effective parameter to study electron density disturbancesThe methodology employed in this study involves the calculation and analysis of ∆H, VTEC, and ROT (Rate of TEC change) [ABSTRACT FROM AUTHOR]

This paper studies the stable degree for profile of networked evolutionary games (NEGs) with disturbances by the semi-tensor product of matrices. Firstly, the algebraic formulation of an NEG with disturbances is established. Secondly, on the basis of algebraic formulation, some concepts about stable profile with disturbances are proposed, including strong k-degree stable and weak k-degree stable, and the corresponding criteria to detect the stable degree are presented. Thirdly, two algorithms for designing controls are given to make the stable profile achieves strong k-degree stable or weak k-degree stable. Finally, an example is given to illustrate the validity of the results. [ABSTRACT FROM AUTHOR]

This paper presents a novel robust adaptive control approach for nonlinear uncertain vehicle suspension system with time delayed actuation and bounded disturbances. The uncertainty and disturbance as well as the input delay on the system are all limited and unknown. This paper explores a control-oriented nonlinear model to accurately describe the dynamics of the vehicle suspension which incorporates uncertainty, disturbance and actuator delay. The controller is designed based on robust and adaptive approaches, which along with guaranteeing general goals for the suspension system is able to assure the stability of the closed-loop system in the Lyapunov concept. Also, due to the use of smooth functions in the robust controller structure, sudden changes in the behavior of system states are prevented. The simulation and comparison results in MATLAB environment show the efficiency of the proposed robust adaptive method in covering the effects of uncertainty, disturbance and time-variant actuator delay.

Restoration involves the recovery and repair of environments because environmental damage is not always irreversible, and communities are not infinitely resilient to such harm. When restoration projects are applied to nature, either directly or indirectly these may take the form of ecological, forestry or hydrological restoration, for example. In the current scenario of global climate change and increasing intensity of disturbances the importance of restoration in all types of ecosystems in order to adapt to the new conditions (so called prestoration) is evident. Whatever the objective of the restoration initiative, there is a lack of consensus as regards common indicators to evaluate the success or failure of the different initiatives implemented. In this study, we have carried out an extensive meta-analysis review of scientific papers aiming to evaluate the outcomes of restoration projects. We have done a review and selected 95 studies implemented in Europe. We explored the main pre-restoration land cover in which restoration initiatives have been implemented, the main causes of degradation, the objective of the restoration action and the indicators selected to analyze the success or failure of the action. We identified a total of 84 indicators in the analyzed papers and compared with the ones proposed for forest in the recent Nature Restoration Law. The analysis revealed five indicators commonly used for the evaluation of restoration initiatives (abundance, coverage, density, Ellenberg indicator, and richness), even where the initial objective has not yet been achieved. Our findings underscore both the benefits and challenges associated with a specific set of harmonized indicators for evaluating the success or failure of restoration initiatives.

The primary objective of this paper was to compare the nutrient content (N, Ca, S, K, P, Mg) of bilberry biomass, both aboveground and underground, growing in different habitats along the altitudinal gradient. The research was conducted in protected areas of the High Tatras National Park (Slovakia). Two different habitats subjected to study, namely spruce forest stands affected by disturbances (D - disturbed forest stands) and stands unaffected by disturbances (U - undisturbed forest stands), were located at different altitudes: 1 100 m a.s.l., 1 250 m a.s.l., and 1 400 m a.s.l. We found significant differences in the soil nutrient content along the altitudinal gradient. The highest content of nutrients was detected mostly at the highest altitudes in both habitats. The minimum reached 0.01 g.kg-1 (phosphorus), while the maximum was 8.33 g.kg-1 (nitrogen). In the case of the bilberry biomass, we found statistically non-significant differences in the content of nutrients among the altitudes within both habitats (D vs. U). The principal component analysis (PCA) showed that the aboveground biomass of bilberry had a significantly higher nutrient content compared to the underground biomass. Nutrient content in aboveground and underground biomass ranged from 1.00 g.kg-1 (phosphorus) to 13.49 g.kg-1 (nitrogen) and from 0.38 g.kg-1 (magnesium) to 7.55 g.kg-1 (nitrogen), respectively. The biological absorption coefficient (element content in dry biomass/element content in soil) reached the highest values mostly at the lowest altitude for both aboveground and underground biomass.

Accurate evaluation of terrestrial carbon balance is essential for designing climate change mitigation policies, and capabilities of remote sensing techniques in monitoring carbon fluxes are widely recognized for their great contributions to regional and global carbon budget accounting. In this review, we synthesized satellite-based data and methodologies to estimate the main flux components of terrestrial carbon balance and their uncertainties over the past two decades. The global gross primary production (GPP) during the period 2001–2022 is 134 ± 14 PgC yr−1, and nearly half of them occurs in tropical forest regions such as South America and Africa. Less than 2% of global GPP is converted into a net carbon sink of 2.28 ± 1.12 PgC yr−1 using satellite-based atmospheric inversion during 2015–2020, and this sink is comparable to the stock change-based estimate (2.49 PgC yr−1) but twice as large as model-based estimate (1.08 ± 0.78 PgC yr−1). By decomposing satellite-derived net carbon balance into different terms including satellite-derived carbon emissions from land-use change and wildfires (3.55 PgC yr−1), we inferred that ~ 43% of global GPP would be respired through soil microbes (57.1 PgC yr−1), but which is higher than the previous bottom-up estimate (39–46 PgC yr−1). We then propose that an accurate remote sensing of terrestrial carbon balance requires to enhance representations of photosynthetic responses to rising CO2 and disturbances, develop satellite-constrained belowground carbon dynamics and separate natural fluxes from anthropogenic CO2 emissions, by integrating multi-source satellite sensors in orbit, revolutionized remote sensing capabilities with focused field campaigns in data-scarce regions.

This paper investigates the problem of sliding mode control for a class of hybrid switched systems with matching disturbances. Firstly, a sliding mode surface is designed, and the corresponding sliding mode equation for the switched system is derived. Then, we analyzed the stability of the sliding mode equation using the Lyapunov function and average dwell time. Moreover, a sliding mode control law is designed with the approach law method to drive the system state to a bounded sliding mode region and then maintain it there subsequently. Finally, an illustrative example is given to demonstrate the efficiency of the approach. [ABSTRACT FROM AUTHOR]

This paper presents a robust optimal control approach for the wheel mobile robot system, which considers the effects of external disturbances, uncertainties, and wheel slipping. The proposed method utilizes an adaptive dynamic programming (ADP) technique in conjunction with a disturbance observer. Initially, the system's state space model is formulated through the utilization of kinematic and dynamic models. Subsequently, the ADP method is employed to establish an online adaptive optimal controller, which solely relies on a single neural network for the purpose of function approximation. The utilization of the disturbance observer in conjunction with the compensation controller serves to alleviate the effects of disturbances. The Lyapunov theorem establishes the stability of the complete closed-loop system and the convergence of the weights of the neural network. The proposed approach has been shown to be effective through simulation under the effect of the disturbances and the change of the desired trajectory. [ABSTRACT FROM AUTHOR]

Cycles of disturbance and recovery govern the temporal dynamics of living coral cover on coral reefs. Monitoring the state of the Great Barrier Reef at regional and individual reef scales has been ongoing by the Long-Term Monitoring Program at the Australian Institute of Marine Science since 1986. After a period of relative stability between 1986 and 2010, the latest decade of surveys recorded increased frequency of intense, large-scale disturbance events and coral cover has reached unprecedented lows and highs in each region. Following the consecutive bleaching events in 2016 and 2017, widespread recovery occurred on the northern and central Great Barrier Reef between 2017 and 2022, which was halted in 2023. An examination of the effects of the 2022 bleaching event revealed that the direct and indirect impacts of this event, along with ongoing crown-of-thorns starfish outbreaks, notable incidences of coral disease, and the passage of a tropical cyclone all contributed to the most recent coral cover changes across the Great Barrier Reef. The prognosis for future disturbances suggests increasing and longer-lasting marine heatwaves, continuing severe tropical cyclones and the ongoing risk of outbreaks of crown-of-thorns starfish. Although the observed capacity for recovery is a cause for cautious optimism for the overall state of the Great Barrier Reef, there is increasing concern for its ability to continue to bounce back in the face of escalating climatic pressure. [ABSTRACT FROM AUTHOR]

In this study, a new fixed-time sliding mode control approach for trajectory tracking control of robotic manipulator systems is devised, which provides fixed-time convergence, robust stabilization, and high precision. A novel fixed-time non-singular fast terminal sliding mode surface (FNFTSMS) with fixed-time convergence is provided, and with settling time independent of the initial condition of the system and can be pre-determined using design parameters. Furthermore, using adaptive disturbance observer and the suggested FNFTSMS, a new composite robust control approach is developed. The adaptive disturbance observer is intended to boost control performance and compensate for unpredictably occurring disturbances. The Lyapunov stability theory is used to establish the fixed-time stability of sliding surface and system states under the suggested composite control strategy. Finally, numerical simulations are carried out using PUMA560 robot in order to demonstrate the effectiveness and efficacy of the proposed control method in terms of accuracy of tracking, fast response, and convergent speed. [ABSTRACT FROM AUTHOR]

In a manufacturing environment the effectiveness of internal problem solving is a key success factor in the service level performance offered to the customers. Broken internal processes need to be fixed immediately or at least in a very short time, in order to fulfill the committed delivery dates. There are several methodologies applied for internal problem solving used by different companies. This article presents a solution worked out for a plant operating in a high-mix low-volume (HMLV) production environment prone to both internal and external disruptions and disturbances. Principles, architecture and information flow in our digitized disruption handling -- so-called escalation -- system will be shortly discussed. Lessons learned in a six-year's period of using the system will also be summarized. The recorded data confirm that with the introduction of the escalation system the capability of the plant to adapt to changing circumstances and disruptions greatly improved. [ABSTRACT FROM AUTHOR]

This paper is focused on asymptotic tracking control of electro-hydraulic actuator (EHA) systems subject to matched and mismatched time-varying disturbances. To counteract the matched disturbance, a novel extended state observer (ESO) is proposed to achieve asymptotic convergence of the estimation error, by incorporating the strictly positive real (SPR) Lyapunov design method and a Nussbaum function. To further suppress the mismatched disturbance, an adaptive robust integral of the sign of the error (RISE) controller is formulated in the backstepping framework based on the proposed ESO. Asymptotic tracking performance is theoretically achieved via closed-loop system stability analysis. The efficacy of the proposed control scheme is verified through comparative experiments executed on an EHA test rig. In this study, a priori bounds of the disturbances and their higher-order derivatives are no longer needed, and only one auxiliary error signal is introduced. This approach loosens the restrictions on the disturbances and reduces the design conservativeness, thus making it promising in practice. [ABSTRACT FROM AUTHOR]

Sensors and actuators frequently encounter unexpected deviations from their optimal operating conditions, making their reliability an essential topic in many electric motor drives. In this paper, a comparison of structured residual synthesis methods for actuator and sensor additive fault detection and isolation (FDI) in a permanent magnet (PM) DC motor, applying two different approaches to the design of primary residuals, is presented. The first method involves a standard approach and is based on system transfer matrix synthesis. The second, more convenient approach involves the synthesis of primary residuals based on the analysis of subsystems that describe the observed system. Both methods are applicable for linear and time-invariant (LTI) systems but were successfully applied to a laboratory system that shows nonlinear behavior, time-variant properties, and is affected by a constant disturbance, thanks to the proposed technique of residual translation with the previous design of internal residuals. With the proposed method, all important performance characteristics of the residual generators such as fault sensitivity, reaction speed, and robustness are achieved. The technique can be applied to all mechatronic systems in general, whose behavior can be with satisfactory accuracy described by an LTI model. Given the transfer functions and state-space model of the system in the presence of faults in the Z domain with reduced order, presented technique is computationally efficient for embedded systems. Also, in addition to fault detection and isolation, the system can identify faults by analyzing fault sensitivities, nominal faults, and stationary residual values, making it superior for most FDI applications. A real-time experiment performed on a laboratory setup, which consists of a DC motor, an amplifier designed in the form of a linear electronic circuit, and a Compact RIO 9075 real-time processor is used to develop the FDI system, to generate residuals and confirm advantages of the proposed FDI technique. [ABSTRACT FROM AUTHOR]

Nature‐based climate solutions (NCS) are championed as a primary tool to mitigate climate change, especially in forested regions capable of storing and sequestering vast amounts of carbon. New England is one of the most heavily forested regions in the United States (>75% forested by land area), and forest carbon is a significant component of climate mitigation policies. Large infrequent disturbances, such as hurricanes, are a major source of uncertainty and risk for policies relying on forest carbon for climate mitigation, especially as climate change is projected to alter the intensity and extent of hurricanes. To date, most research into disturbance impacts on forest carbon stocks has focused on fire. Here, we show that a single hurricane in the region can down between 121 and 250 MMTCO2e or 4.6%–9.4% of the total aboveground forest carbon, much greater than the carbon sequestered annually by New England's forests (16 MMTCO2e year−1). However, emissions from hurricanes are not instantaneous; it takes approximately 19 years for downed carbon to become a net emission and 100 years for 90% of the downed carbon to be emitted. Reconstructing hurricanes with the HURRECON and EXPOS models across a range of historical and projected wind speeds, we find that an 8% and 16% increase in hurricane wind speeds leads to a 10.7‐ and 24.8‐fold increase in the extent of high‐severity damaged areas (widespread tree mortality). Increased wind speed also leads to unprecedented geographical shifts in damage, both inland and northward, into heavily forested regions traditionally less affected by hurricanes. Given that a single hurricane can emit the equivalent of 10+ years of carbon sequestered by forests in New England, the status of these forests as a durable carbon sink is uncertain. Understanding the risks to forest carbon stocks from disturbances is necessary for decision‐makers relying on forests as a NCS. [ABSTRACT FROM AUTHOR]

The path tracking performance of autonomous vehicles is degraded by common disturbances, especially those that affect the safety of autonomous vehicles (AVs) in obstacle avoidance conditions. To improve autonomous vehicle tracking performances and their computational efficiency when subjected to common disturbances, this paper proposes a tube linear model predictive controller (MPC) framework for autonomous vehicles. A bicycle vehicle dynamics model is developed and employed in the tube MPC control design in the proposed framework. A robust invariant set is calculated with an efficient linear programming (LP) method, and it is used to guarantee that the constraints are satisfied under common disturbance conditions. The results show that the computational cost of robust positively invariant sets that are constructed by the LP method is much less than that obtained by the traditional method. In addition, all the trajectories of the tube linear MPC successfully avoided obstacles when under disturbance conditions, but only about 80% of the trajectories obtained with the traditional MPC successfully avoided obstacles under disturbance conditions. The proposed framework is effective. [ABSTRACT FROM AUTHOR]

The primary objective of this paper was to compare the nutrient content (N, Ca, S, K, P, Mg) of bilberry biomass, both aboveground and underground, growing in different habitats along the altitudinal gradient. The research was conducted in protected areas of the High Tatras National Park (Slovakia). Two different habitats subjected to study, namely spruce forest stands affected by disturbances (D - disturbed forest stands) and stands unaffected by disturbances (U - undisturbed forest stands), were located at different altitudes: 1 100 m a.s.l., 1 250 m a.s.l., and 1 400 m a.s.l. We found significant differences in the soil nutrient content along the altitudinal gradient. The highest content of nutrients was detected mostly at the highest altitudes in both habitats. The minimum reached 0.01 g·kg-1 (phosphorus), while the maximum was 8.33 g·kg-1 (nitrogen). In the case of the bilberry biomass, we found statistically non-significant differences in the content of nutrients among the altitudes within both habitats (D vs. U). The principal component analysis (PCA) showed that the aboveground biomass of bilberry had a significantly higher nutrient content compared to the underground biomass. Nutrient content in aboveground and underground biomass ranged from 1.00 g·kg-1 (phosphorus) to 13.49 g·kg-1 (nitrogen) and from 0.38 g·kg-1 (magnesium) to 7.55 g·kg-1 (nitrogen), respectively. The biological absorption coefficient (element content in dry biomass/element content in soil) reached the highest values mostly at the lowest altitude for both aboveground and underground biomass. [ABSTRACT FROM AUTHOR]