Local Disturbances Research Articles

A Coordinated Voltage-Frequency Support Method for VSC-MTDC Integrated Offshore Wind Farms System

Voltage and frequency stability is one of the major concerns with the continuously increasing penetration of offshore wind farms (OWFs) integrated into onshore grid via VSC-MTDC system, and it is a challenge to coordinate its low voltage ride-through (LVRT) and frequency regulation (FR) control when a local fault or large disturbance occurs in onshore grid. To address this challenge, a coordinated voltage-frequency support (CVFS) method for the VSC-MTDC integrated OWFs system is proposed in three parts: 1) an adaptive maximum power point tracking (MPPT) strategy is developed for wind turbines (WTs) to satisfy the power demands for LVRT and FR; 2) an active and reactive power quantification strategy, which firstly considers the static load characteristics of nodes nearest the grid side VSC (GSVSC) stations, is proposed for GSVSC stations to support LVRT and FR respectively; 3) an adaptive power allocation strategy, which considers the capacity constraint and the coordination factor with deviation and rate of change of voltage and frequency of different GSVSC stations, is conducted to achieve differential power distribution between LVRT and FR. Extensive test results have validated the effectiveness and performance of the proposed CVFS method.

Paleomicrobiology: Tracking the past microbial life from single species to entire microbial communities.

By deciphering information encoded in degraded ancient DNA extracted from up to million-years-old samples, molecular paleomicrobiology enables to objectively retrace the temporal evolution of microbial species and communities. Assembly of full-length genomes of ancient pathogen lineages allows not only to follow historical epidemics in space and time but also to identify the acquisition of genetic features that represent landmarks in the evolution of the host-microbe interaction. Analysis of microbial community DNA extracted from essentially human paleo-artefacts (paleofeces, dental calculi) evaluates the relative contribution of diet, lifestyle and geography on the taxonomic and functional diversity of these guilds in which have been identified species that may have gone extinct in today's human microbiome. As for non-host-associated environmental samples, such as stratified sediment cores, analysis of their DNA illustrates how and at which pace microbial communities are affected by local or widespread environmental disturbance. Description of pre-disturbance microbial diversity patterns can aid in evaluating the relevance and effectiveness of remediation policies. We finally discuss how recent achievements in paleomicrobiology could contribute to microbial biotechnology in the fields of medical microbiology and food science to trace the domestication of microorganisms used in food processing or to illustrate the historic evolution of food processing microbial consortia.

On the uncertain intensity estimate of the 1859 Carrington storm

A study is made of the intensity of the Carrington magnetic storm of September 1859 as inferred from visual measurements of horizontal-component geomagnetic disturbance made at the Colaba observatory in India. Using data from modern observatories, a lognormal statistical model of storm intensity is developed, to characterize the maximum-negative value of the storm-time disturbance index (maximum –Dst) versus geomagnetic disturbance recorded at low-latitude observatories during magnetic storms. With this model and a recently published presentation of the Colaba data, the most likely maximum –Dst of the Carrington storm and its credibility interval are estimated. A related model is used to examine individual Colaba disturbance values reported for the Carrington storm. Results indicate that only about one in a million storms with maximum –Dst like the Carrington storm would result in local disturbance greater than that reported from Colaba. This indicates that either the Colaba data were affected by magnetospheric-ionospheric current systems in addition to the ring current, or there might be something wrong with the Colaba data. If the most extreme Colaba disturbance value is included in the analysis, then, of all hypothetical storms generating the hourly average disturbance recorded at Colaba during the Carrington storm, the median maximum –Dst = 964 nT, with a 68% credibility interval of [855,1087] nT. If the most extreme Colaba disturbance value is excluded from the analysis, then the median maximum –Dst = 866 nT, with a 68% credibility interval of [768,977] nT. The widths of these intervals indicate that estimates of the occurrence frequency of Carrington-class storms are very uncertain, as are related estimates of risk for modern technological systems.

Small Signal Stability Analysis of Kalimantan 500 KV Electricity System

Small signal stability refers to the ability of a system to return to equilibrium after experiencing a small disturbance. In this research, the Kalimantan electricity system will be analyzed for the stability of its small signal. Analysis of the stability of small signals in electrical systems including local disturbances and inter-area disturbances. The Kalimantan system will be analyzed using Power Factory software. System analysis was carried out by evaluating the eigenvalues ​​(real part and imaginary part), oscillation frequency (damped frequency and frequency ratio) produced in the Kalimantan 500 KV electricity analysis. In the analysis results, the Kalimantan system is categorized as stable as indicated by the real part and imaginary part values ​​located on the negative side of the Cartesian coordinate curve. Then, analyzing small signals, there are 117 modes categorized as local mode and 4 modes categorized as inter area mode.

Myocardial strain changes over a 1-month follow-up in Takotsubo syndrome: a case report

Among various diagnostic methods, echocardiography (EchoCG) is most often used to identify Takotsubo syndrome. Left ventricular apical ballooning and the absence of permanent local contractility disturbances makes it possible to confirm the diagnosis. Currently, the available literature provides insufficient data on longitudinal strain (LS) of various cardiac chambers in this condition. The current case report demonstrates complete restoration of left heart LS within 1 month with its initial significant decrease.

A two-stage exacerbated hypoxia nanoengineering strategy induced amplifying activation of tirapazamine for microwave hyperthermia-chemotherapy of breast cancer

Microwave hyperthermia (MH) is an emerging treatment for solid tumors, such as breast cancer, due to its advantages of minimally invasive and deep tissue penetration. However, MH induced tumor hypoxia is still an obstacle to breast tumor treatment failure. Therefore, an original nanoengineering strategy was proposed to exacerbate hypoxia in two stages, thereby amplifying the efficiency of activating tirapazamine (TPZ). And a novel microwave-sensitized nanomaterial (GdEuMOF@TPZ, GEMT) is designed. GdEuMOF (GEM) nanoparticles are certified excellent microwave (MW) sensitization performance, thus improving tumor selectivity to achieve MH. Meanwhile MW can aggravate the generation of thrombus and caused local circulatory disturbance of tumor, resulting in the Stage I exacerbated hypoxia environment passively. Due to tumor heterogeneity and uneven hypoxia, GEMT nanoparticles under microwave could actively deplete residual oxygen through the chemical reaction, exacerbating hypoxia level more evenly, thus forming the Stage II of exacerbated hypoxia environment. Consequently, a two-stage exacerbated hypoxia GEMT nanoparticles realize amplifying activation of TPZ, significantly enhance the efficacy of microwave hyperthermia and chemotherapy, and effectively inhibit breast cancer. This research provides insights into the development of progressive nanoengineering strategies for effective breast tumor therapy.

Advances in Numerical Data Visualization of Flow around a Square Cylinder

In this work, we present a grid study oriented to capture 3D flow simulations around smooth and wrinkled cylinders that could have practical applications in various engineering areas. The study considers three Reynolds numbers, namely, a benchmark Re =2.14×104 and two orders of magnitude above and below it. The main contributions of the paper relate to the optimization of the computational mesh for the spanwise direction of the wind flow that results from the computational-mathematical framework employed, in addition to a novel visualization technique that unfolds features in the recording data that could otherwise be hidden when using traditional plots. We compare our benchmark results with those reported by other authors to conclude that the intermediate resolution grids employed with the widest spanwise provide acceptable results. Furthermore, the new visualization technique offers significant advantages compared to traditional pressure maps, regarding clarity for observing and interpreting local flow disturbances, making variations with Re clearer, and by enabling the detection of asymmetries.

Clinical characterisation of women with persistent genital arousal disorder: the iPGAD-study

Persistent Genital Arousal Disorder (PGAD) is a rare condition—mostly in women—where patients perceive prolonged genital arousal without any sexual desire or stimulation. Etiopathological considerations reach from peripheral to central issues over local disturbance of the pudendal nerve to neuropathy, psychosocial, and pharmacological theories. Since well controlled clinical studies about PGAD in conjunction with a mental and somatic health status are missing, this study is a detailed clinical investigation of PGAD patients compared to healthy controls. 26 women who fulfilled diagnostic criteria for PGAD were compared to 26 age matched healthy controls. Investigations included comparison of vegetative, gynaecological and sexual history, psychiatric features as well as a (neuro-)radiological, neurophysiological and gynaecological examination. Moreover, a detailed clinical characterisation of PGAD symptoms was performed. PGAD symptoms were mostly characterised as tingling or prickling and were permanently present. In over 80%, PGAD symptoms were located in the clitoris. Almost 70% reported radiations to other regions of the body. Most frequent trigger factors were tight clothes, mental stress, driving a car/bus/bicycle and sexual intercourse. Relieving factors were mainly distraction, relaxation, physical exercise, masturbation and swimming. In group comparisons, PGAD presented with significant higher rates of sexual dysfunctions, spontaneous orgasms, swelling of the genitals, extraordinary lubrication as well as higher rates in depression, agoraphobia, generalized anxiety disorder and lifetime panic disorder. Significantly more PGAD patients were diagnosed with restless legs symptoms. In contrast childhood traumatization, somatization disorder, suicidality, gynaecological as well as neurophysiological examination of the pudendal nerve were not different between the groups. MRI of the brain, pelvis and spinal cord was unsuspicious and incidental findings - including Tarlov cysts or pelvic venous congestion - were equally distributed among the groups. In summary, our study provides a careful characterization of women with PGAD highlighting a serious mental burden, most probably as a consequence of PGAD. With the current set of clinical investigations there was no evidence of a clear causal relationship to a specific clinical finding as it has been previously discussed. Future studies and additional techniques will have to further explore where and how in the peripheral or central nervous systems PGAD develops.

Disturbance frequency directs microbial community succession in marine biofilms exposed to shear.

Disturbances are major drivers of community succession in many microbial systems; however, relatively little is known about marine biofilm community succession, especially under antifouling disturbance. Antifouling technologies exert strong local disturbances on marine biofilms, and resulting biomass losses can be accompanied by shifts in biofilm community composition and succession. We address this gap in knowledge by bridging microbial ecology with antifouling technology development. We show that disturbance by shear can strongly alter marine biofilm community succession, acting as a selective filter influenced by frequency of exposure. Examining marine biofilm succession patterns with and without shear revealed stable associations between key prokaryotic and eukaryotic taxa, highlighting the importance of cross-domain assessment in future marine biofilm research. Describing how compounded top-down and bottom-up disturbances shape the succession of marine biofilms is valuable for understanding the assembly and stability of these complex microbial communities and predicting species invasiveness.

How landscape traits affect boreal mammal responses to anthropogenic disturbance

Understanding mammalian responses to anthropogenic disturbance is challenging, as ecological processes and the patterns arising therefrom notoriously change across spatial and temporal scales, and among different landscape contexts. Responses to local scale disturbances are likely influenced by landscape context (e.g., overall landscape-level disturbance, landscape-level productivity). Hierarchical approaches considering small-scale sampling sites as nested holons within larger-scale landscapes, which constrain processes in lower-level holons, can potentially explain differences in ecological processes between multiple locations. We tested hypotheses about mammal responses to disturbance and interactions among holons using collected images from 957 camera sites across 9 landscapes in Alberta from 2007 to 2020 and examined occurrence for 11 mammal species using generalized linear mixed models. White-tailed deer occurred more in higher disturbed sites within lower disturbed landscapes (β = −0.30 [−0.4 to −0.15]), whereas occurrence was greater in highly disturbed sites within highly disturbed landscapes for moose (β = 0.20 [0.09–0.31]), coyote (β = 0.20 [0.08–0.26]), and lynx (β = 0.20 [0.07–0.26]). High disturbance sites in high productivity landscapes had higher occurrence of black bears (β = −0.20 [−0.46 to −0.01]), lynx (β = −0.70 [−0.97 to −0.34]), and wolves (β = −0.50 [−0.73 to −0.21]). Conversely, we found higher probability of occurrence in low productivity landscapes with increasing site disturbance for mule deer (β = 0.80 [0.39–1.14]), and white-tailed deer (β = 0.20 [0.01–0.47]). We found the ecological context created by aggregate sums (high overall landscape disturbance), and by subcontinental hydrogeological processes in which that landscape is embedded (high landscape productivity), alter mammalian responses to anthropogenic disturbance at local scales. These responses also vary by species, which has implications for large-scale conservation planning. Management interventions must consider large-scale geoclimatic processes and geographic location of a landscape when assessing wildlife responses to disturbance.

Structural control on the alteration and fluid flow in the lithocap of the Allumiere-Tolfa epithermal system

Zones of advanced argillic alteration with general low permeability (i.e., lithocaps) are common place in the shallow parts of porphyry and epithermal ore deposits and active geothermal systems. The study of structural control on alteration distributions is of paramount importance for exploitation purposes as it really influences the caprock efficiency. We present the results of a structural-mineralogical study carried out in the lithocap of the Allumiere-Tolfa epithermal system (Northern Apennines). We characterized the composition, textures and physical properties (i.e., in-situ permeability; relative rock strength) of alteration facies. We then integrated field structural analysis with analysis of a virtual outcrop model to reconstruct the geometry of principal fluid-corridors. It resulted that advanced argillic alteration was promoted by circulation of highly reactive fluid(s) along a complex network of NE- and NW-striking faults and fractures dissecting the acidic volcanic dome. Such structures likely developed in response to a local disturbance of the regional stress field due to the extrusion of the Tolfa dome, which controlled the syn-extensional mineralization of the Allumiere-Tolfa area.

Atrial fibrosis heterogeneity is a risk for atrial fibrillation in pigs with ischaemic heart failure.

Atrial fibrillation (AF) is the most common arrhythmia and is associated with considerable morbidity and mortality. Ischaemic heart failure (IHF) remains one of the most common causes of AF in clinical practice. However, ischaemia-mediated mechanisms leading to AF are still incompletely understood, and thus, current treatment approaches are limited. To improve our understanding of the pathophysiology, we studied a porcine IHF model. In pigs, IHF was induced by balloon occlusion of the left anterior descending artery for 90 min. After 30 days of reperfusion, invasive haemodynamic measurements and electrophysiological studies were performed. Masson trichrome and immunofluorescence staining were conducted to assess interstitial fibrosis and myofibroblast activation in different heart regions. After 30 days of reperfusion, heart failure with significantly reduced ejection fraction (left anterior obique 30°, 34.78 ± 3.29% [IHF] vs. 62.03 ± 2.36% [control], p < .001; anterior-posterior 0°, 29.16 ± 3.61% vs. 59.54 ± 1.09%, p < .01) was observed. These pigs showed a significantly higher susceptibility to AF (33.90% [IHF] vs. 12.98% [control], p < .05). Histological assessment revealed aggravated fibrosis in atrial appendages but not in atrial free walls in IHF pigs (11.13 ± 1.44% vs. 5.99 ± .86%, p < .01 [LAA], 8.28 ± .56% vs. 6.01 ± .35%, p < .01 [RAA]), which was paralleled by enhanced myofibroblast activation (12.09 ± .65% vs. 9.00 ± .94%, p < .05 [LAA], 14.37 ± .60% vs. 10.30 ± 1.41%, p < .05 [RAA]). Correlation analysis indicated that not fibrosis per se but its cross-regional heterogeneous distribution across the left atrium was associated with AF susceptibility (r = .6344, p < .01). Our results suggest that left atrial cross-regional fibrosis difference rather than overall fibrosis level is associated with IHF-related AF susceptibility, presumably by establishing local conduction disturbances and heterogeneity.

Multicell Thin-walled Method for Solid Multimaterial Beams

In this paper we developed the Multicell Thin-walled Method for Solid Multimaterial Beams, which combines structural idealization used in aircraft components, thin-walled beam theory and homogenization techniques from composite materials applied to discrete models, to obtain the cross-section stress fields of solid beams made of multiple orthotropic and isotropic materials. This method idealizes a solid multimaterial cross-section as a multicell thin-walled section to accurately obtain complex stress fields while significantly reducing the solution time, as well as the computational cost, when compared to classical 3D finite element analyses. This method was implemented in a computer program and three examples were analyzed to validate results with the finite element method. Both methods show almost identical results in regions not affected by local disturbances.

Improving ductility of multilayer TWIP/Maraging steel through shear band delocalization and periodic multiple necking controlled by layer thickness

Layer thickness is a crucial parameter for enhancing the strengthening-toughening effects of multilayer steels. In this work, the tensile behaviors of multilayer TWIP/Maraging steels reveal a notable size effect dependent on layer thickness. The fracture elongation and work hardening gradually increase with the decrease of layer thickness, which is attributed to the gradual increase of micro shear bands and periodic multiple necking during the tensile deformation. These intertwined phenomena effectively dissipate the deleterious impacts of localized strains and promote strain delocalization. The multilayer with a thinner layer possesses enhanced tensile strength, mainly attributed to the refined elongated grains. The observed phenomena, along with the corresponding evolution processes of the shear band and periodic necking, are also simulated using finite element analysis based on local disturbance theory. This work further clarifies the effect of layer thickness on the synergistic deformation behavior and the toughening mechanism of heterogeneous multilayer steel.

Estimating the spatial amplification of damage caused by degradation in the Amazon.

The Amazon rainforests have been undergoing unprecedented levels of human-induced disturbances. In addition to local impacts, such changes are likely to cascade following the eastern-western atmospheric flow generated by trade winds. We propose a model of spatial and temporal interactions created by this flow to estimate the spread of effects from local disturbances to downwind locations along atmospheric trajectories. The spatial component captures cascading effects propagated by neighboring regions, while the temporal component captures the persistence of local disturbances. Importantly, all these network effects can be described by a single matrix, acting as a spatial multiplier that amplifies local forest disturbances. This matrix holds practical implications for policymakers as they can use it to easily map where the damage of an initial forest disturbance is amplified and propagated to. We identify regions that are likely to cause the largest impact throughout the basin and those that are the most vulnerable to shocks caused by remote deforestation. On average, the presence of cascading effects mediated by winds in the Amazon doubles the impact of an initial damage. However, there is heterogeneity in this impact. While damage in some regions does not propagate, in others, amplification can reach 250%. Since we only account for spillovers mediated by winds, our multiplier of 2 should be seen as a lower bound.

Bridge Acceleration Data Cleaning Based on Two-Stage Classification Model with Multiple Feature Fusion

Over the past few decades, rapid economic development has led to the establishment of numerous monitoring systems, resulting in the accumulation of vast amounts of monitoring data. Among these data, dynamic acceleration data stand out prominently. However, the quality of collected acceleration data is often compromised due to factors such as challenging operational environments and sensor malfunctions. This severely hampers the value extracted from the data. Although manual identification and classification of data anomalies are more reliable, they are time consuming and labor intensive. To address the challenge of identifying and classifying anomalies in massive acceleration data, this paper proposes a two-stage model for intelligent data cleaning. Firstly, raw acceleration data are transformed into IPDF and PSD features, and a one-dimensional convolutional neural network is trained to preliminarily identify and classify acceleration data anomalies. Subsequently, the RPV indicator is extracted from the original data of the normal and outlier categories to achieve precise classification based on threshold values. The proposed method is successfully validated using acceleration monitoring data from a large-span arch bridge, achieving an accuracy of over 99%. Furthermore, compared to directly employing a one-dimensional CNN classification model, the approach significantly enhances the model’s perception of local significant disturbances.

Associations between recent land use history and urban forest composition

More than half of the world’s population lives in urban areas. Sustaining healthy urban forests is increasingly relevant to this population given the wide range of economic, ecological, and social benefits that urban forests provide. Yet forests in cities grow in sites that are fragmented, with frequent disturbance, altered soils, and complex land use history, which can lead to the degradation of forest conditions and the benefits they provide. We measured forest composition and structure in 1124 plots across 53 parks in New York City’s (NYC) 2,497-ha natural area forests and uplands. To better understand the factors responsible for their current condition, we documented historical land use in each plot using aerial imagery going back 90 years, quantified edge effects using remote sensing, and field-measured contemporary disturbances, soil characteristics and light. In the last 90 years, the majority of contemporary natural areas in NYC have recolonized from farmland, built, landscaped lawn, and open field cover-types to forests (from a mean of 37% to 76% forest cover). Areas previously documented as having human land use (e.g. arable agriculture), now have double the amount of invasive species cover compared to sites that were forested or natural areas in the last 90 years. Contemporary measures of forest edge, light, and soil pH have a stronger association with native species basal area, species richness, and invasive species cover, but have an additive effect with measures of historical land cover and local site-level disturbances. We find that a history of non-forest cover, in combination with high soil pH and edge adjacency, was associated with the most invaded contemporary forests. Overall, it appears that a non-forest land use history may be a precursor to altered environmental conditions, making it an important lens upon which to understand forest succession more broadly in complex human-dominated forests, like those in New York City.

Artificial light at night: a global disruptor of the night-time environment.

Light pollution is the alteration of the natural levels of darkness by an increased concentration of light particles in the night-time environment, resulting from human activity. Light pollution is profoundly changing the night-time environmental conditions across wide areas of the planet, and is a relevant stressor whose effects on life are being unveiled by a compelling body of research. In this paper, we briefly review the basic aspects of artificial light at night as a pollutant, describing its character, magnitude and extent, its worldwide distribution, its temporal and spectral change trends, as well as its dependence on current light production technologies and prevailing social uses of light. It is shown that the overall effects of light pollution are not restricted to local disturbances, but give rise to a global, multiscale disruption of the night-time environment. This article is part of the theme issue 'Light pollution in complex ecological systems'.

Feasibility of the assessment of longitudinal systolic deformation of the left ventricle in transesophageal atrial pacing stress echocardiography. Clinical case

The article describes a clinical case of registration of longitudinal systolic deformation of the left ventricle using speckle-t racking technology during stress- echocardiography with transesophageal atrial pacing in a patient with coronary heart disease. A feature of the clinical case is the identification of changes in the longitudinal deformation of the left ventricular not only in the zone of visible local disturbances of myocardial contractility, but also in other zones, followed by the identification of hemodynamically significant stenoses of the coronary arteries, which supply the zones with defective longitudinal deformation of left ventricular, but without visible local disturbances of myocardial contractility. The presented case shows the prospects of using the evaluation of left ventricular deformation indicators during stress echocardiography with transesophageal atrial pacing.

Self-correction of the ectopic eruption of the maxillary first permanent molar and its predictive factors: A systematic review.

Ectopic eruption of the maxillary first permanent molar is a local disturbance that affects the development of the occlusion. To evaluate the occurrence of self-correction of maxillary first permanent molar's ectopic eruption and its predictive factors. Five electronic databases and part of the gray literature were investigated. The risk of bias was assessed using the Newcastle-Ottawa scale and the certainty of evidence using the GRADE tool. Four studies were selected: Three had a low risk of bias, and one, moderate. Evidence with a moderate level of certainty was generated, indicating a possibility of 47%-78% of spontaneous correction up to 7 years of age. Supporting the prognosis, whether reversible or irreversible, there was a positive correlation between the severity of the atypical distal resorption of the second primary molar, a higher magnitude of impaction, a larger eruption angle, and a bilateral occurrence with the irreversibility of the cases. Spontaneous correction of the ectopic eruption of the maxillary first permanent molar is feasible and dependent on the severity of predictive factors. Early intervention is mandatory in irreversible cases.