Characteristics Of Disturbances Research Articles

Diagnosis of unsteady disturbance characteristics induced by the tip leakage vortex in a compressor based on data-driven modal decomposition methods

The structural information about the tip leakage vortex at the design point remains largely unknown. Here, the dynamic mode decomposition method is utilized to visualize the main coherent structures corresponding to unsteady disturbance frequencies induced by the tip leakage vortex of an isolated rotor at the design point. The results show that the tip clearance size has a significant impact on unsteady disturbance characteristics at the blade tip region. The flow field within the blade tip region can be categorized into four distinct regions: the formation region of the main tip leakage vortex (MTLV), the formation region of the secondary tip leakage vortex (STLV), the merging zone where the MLTV and the STLV interact, and the vortex shedding zone induced by the leakage vortex breakdown. The disturbance peak in the frequency domain decreases from 121.3 RF to 70.96 RF as the tip clearance size increases from 1.5% blade height to 2%, resulting in a reduction of 41.36%. The increase in the tip clearance size amplifies unsteady disturbances caused by the MTLV and STLV. The STLV exhibits more pronounced oscillatory characteristics than the MTLV. The unsteady disturbance induced by the MLTV mainly occurs at around 0.5 blade passing frequency (BPF). In contrast, high-frequency unsteady disturbances (>1 BPF) in the flow field are caused by vortex shedding resulting from the interaction and collision between the STLV and the MTLV. A better understanding of the unsteady disturbance characteristics induced by leakage vortex benefits the study of stall warning technology.

An autonomous and high-accuracy gravity disturbance compensation scheme for rotary inertial navigation system

Abstract With the increasing demands for long-endurance and high-accuracy inertial navigation system (INS), gravity disturbance has been identified as one of the major error sources with decisive effects on the performance of INS. To address the problem, this paper proposes an autonomous and high-accuracy gravity disturbance compensation scheme for rotary INS (RINS). The high-accuracy velocity measured by the laser Doppler velocimeter is fused with the angular velocity measured by the gyroscope to obtain navigation parameters, such as velocity, position and attitude, that are not affected by gravity disturbance. The navigation parameters independent of gravity disturbance are matched with the gravity disturbance-related navigation parameters output by RINS, and a measurement model containing gravity disturbance information is obtained. Besides, the intrinsic coupling relationship between gravity disturbance, gravity disturbance rate and gravity disturbance gradient is revealed, and a state-space model is established to accurately reflect the time-varying characteristics of gravity disturbance. Furthermore, the gravity disturbance is estimated and compensated in real-time through the optimal estimation algorithm. The results of vehicle experiments indicate that the gravity disturbance estimation precision of the proposed scheme is better than 2.15 mGal (1σ), and its horizontal position accuracy is better than 50 m at a driving distance of 80 km.

An intelligent complex power quality disturbance recognition method based on two dimension encoding conversion and machine vison

This study proposes an intelligent methodology for accurate identification of complex power quality disturbance (PQD) based on 2D encoding conversion and machine vision. Firstly, a 2D image encoding method as improved Markov transition field (IMTF) is proposed to convert 1D PQD signals to 2D images, which can realize the enhancement of disturbance feature display. It can solve the information loss and duplication problems of traditional Markov transition field (MTF). Then, a new classification method AFF-ResNetXt50 is proposed to realize the PQD accurate recognition. It can address the problem that traditional ResNetXt50 is susceptible to the interference from irrelevant information and thus severely degrades the classification accuracy. Compared with other popular methods, this proposed method can obtain higher accuracy as 98.5 % for PQD signals recognition. Finally, PQD experimental platform is established, and IEEE PES dataset is also used to certify the proposed method has the excellent performances and robustness.

Clinical and hematological characteristics of complicated and intact otitis media

Purpose: to evaluate clinical and hematological features and identify patterns in hematological indices in patients with complicated and uncomplicated forms of otitis media.
 Materials and methods: The study included 30 patients with otitis media aged from 18 to 70 years: 24 patients (80%) had an uncomplicated course, 6 (20%) had a complicated course (cholesteatomas, mastoiditis). The diagnosis was established taking into account the clinical recommendations of the Russian Ministry of Health (2022) on the basis of a comprehensive clinical and laboratory examination, otoscopy, and audiological studies.
 Clinical, anamnestic and statistical methods were used. Calculation of hematological indices was carried out using a computer program. Statistical analysis was carried out using the Statistica 10 package. The critical level of statistical significance when testing scientific hypotheses was p 0.05.
 Results and conclusions. In the group of patients with complicated otitis media, a more vivid clinical picture and more pronounced changes in hematological parameters were observed. Noteworthy are the features of disturbances in the state of immune homeostasis: with complicated otitis, the ISLE indicator increased 3 times more often, which indicates the predominance of an immediate type reaction in the development of complications. The macrophage system index (MSI) was changed in uncomplicated otitis compared to complicated patients, which indicates a violation of cellular phagocytic protection in otitis media. In all cases, a violation of the effector and affector links of immunity (IAM) was revealed, with a predominance of the effector pathway. In 80% of cases of otitis, disturbances in the interaction of humoral and cellular immunity (LI) were observed.
 The multidirectionality of the results obtained requires their further study in order to develop an algorithm for personalized diagnosis of patients with otitis media.

Quantitative Representation of Disturbance Waveform for Microgrid Connected PCC Voltages Using Improved Atomic Decomposition

The fluctuation of microgrid power flow leads to serious voltage problems at the point of common coupling (PCC). The quantitative representation of the disturbance parameters of the voltage waveform at the PCC is necessary for evaluating and controlling the impact of distributed generation in the microgrid on the power system. An improved atomic decomposition (IAD) method is proposed to represent the disturbance parameters quantitatively and efficiently. Based on the disturbance characteristics of the PCC voltage, a coherent atom dictionary composed of four subdictionaries is constructed to improve the decomposition efficiency. To further improve the computational efficiency, an improved matching pursuits algorithm is proposed by alternating the search way to extract the disturbance components in the atomic decomposition. Meanwhile, simulation results show that the proposed IAD method has better antinoise and disturbance parameters quantization ability than wavelet transform.

Turtles for the ancestors: A zooarchaeological study of ritual deposits on Fakahina, Tuamotu archipelago (French Polynesia)

AbstractRituals and feasting ceremonies at Polynesian marae depict culturally complex relationships between humans and animals that cannot be explained by subsistence alone. In Central‐East Polynesia, this topic still requires the elaboration of a “ritual zooarchaeology” framework. Using sea turtle assemblages from three sacred sites on Fakahina atoll (Tuamotu), this study offers a preliminary approach to faunal deposits from ritual contexts. Following systematic excavations of marae on Fakahina, analysis aimed to determine whether faunal deposits could be linked with intentional feasting and offering behaviours. To detect how ritual actions were organised through space, skeletal and taphonomic variables were examined for both overall sites and “sub‐assemblages” within sites based on the spatial associations of fauna with site features.At certain site features, derived quantitative units such as %MAU and recovery rate could identify potential offering behaviours through the intentional sorting of culturally significant body parts. The taphonomic signatures of site features could also identify open or closed deposition environments, assisting with the identification of disturbed features as either exposed platforms or enclosed cists. In addition to highlighting previously undocumented complexity in the use of site features, an overall comparison of turtle remains from the three sites shows the potential of these methods to explore variation in ritual practices.

Accurate classification of power quality disturbance based on 3D visualized spiral curve and hybrid ER-MVCNN model

This work proposes a new method for accurate power quality disturbance (PQD) classification. Firstly, 3D-visualized spiral curve (3D-VSC) is innovatively proposed to convert 1D PQD signal into 3D spiral curve. It can display time-frequency information in multi-dimensional perspectives and the disturbance characteristics more intuitively in image visual sense, which can realize PQD features enhancement. Secondly, efficient channel attention-ResNet multi-view convolution neural network (ER-MVCNN) hybrid model is creatively proposed by introducing ECA-ResNet as feature extraction module. It can solve limitations of multi-view convolution neural network (MVCNN) in single-view feature extraction and defects of multi-view feature fusion in the weighting problem, which can effectively achieve classification accuracy to 99.68 %. Comparison experiments with MVCNN, AlexNet-MVCNN, VGGNet-MVCNN, ResNet18-MVCNN, and SENet-ResNet-MVCNN show that ER-MVCNN has higher accuracy by 12.4 %, 6.79 %, 6.14 %, 3.86 %, and 0.88 % respectively. Finally, through establishing PQD experiment platform and IEEE PES datasets to verify high accuracy and robustness of proposed method.

Characteristics of ionospheric disturbances during the 2021 Typhoon Chanthu based on GPS and GLONASS

Severe typhoons often result in substantial economic and human losses. Therefore, near-real-time monitoring and forecasting of severe typhoons have a significant importance. In this paper, characteristics of ionospheric disturbances during the 2021 Typhoon Chanthu are estimated and investigated from GPS and GLONASS measurements. We calculate high-precision de-trended and filtered ionospheric vertical total electron content (VTEC) data based on GPS and GLONASS data from intensive Global Navigation Satellite System (GNSS) observations at 30-second intervals in Taiwan. Based on the VTEC values, we analyze the characteristics of ionospheric disturbances caused by Typhoon Chanthu, such as the time of appearance of ionospheric disturbances, changes in the magnitude of these disturbances, alterations in two-dimensional disturbances, fluctuations in the speed of disturbance propagation, and shifts in the frequency spectrum. The results reveal that both GPS-TEC and GLONASS-TEC exhibit noticeable disturbances during the specified timeframe. These disturbances are accompanied by the occurrence of “N”-type anomalies in TEC. Notably, at the occurrence of the disturbance, the elevation angle of GPS PRN32 and GLONASS PRN1 satellites is approximately 50°-55°, and their respective distances from the typhoon eye are roughly 350 km and 150 km. The propagation velocity and center frequency of the ionospheric disturbances are located in the range of gravity waves. Specifically, the disturbances propagation speeds of GPS PRN32 and GLONASS PRN1 are approximately 129.36 m/s and 128.33 m/s, respectively, while the center frequencies are about 1.17 mHz and 1.43 mHz. The ionospheric perturbations observed by GPS and GLONASS exhibit certain similarities, which provide valuable insights into the relationship between typhoons and ionospheric disturbances.

Migration mechanisms of 90Sr and 137Cs on terraces

In order to investigate the impact of environmental conditions on the distribution and migration of 90Sr in the Longji terrace environment, the activity concentrations of 90Sr and 137Cs were determined. The activity concentration ranges of 90Sr and 137Cs in surface soil were 0.15–1.04 Bq/kg and 2.16–6.94 Bq/kg, respectively. These results showed that there was a similar trend between the activity concentration of 90Sr and 137Cs in the surface soil along the runoff path and their activity concentration were influenced by the slope of the terraced terrain. On the other hand, the activity ranges of 90Sr and 137Cs in soil cores were 0.01–2.74 Bq/kg and 0.43–7.19 Bq/kg, respectively. These results indicate that the migration mechanism of 90Sr is different from that of 137Cs. As compared with 137Cs, 90Sr is significantly influenced by the moisture content. In addition, high span of 137Cs/90Sr activity ratios were found in this study, which were attributed to the characteristics of cultivated land and frequent artificial disturbances that intensified the migration of 90Sr.

Analysis of fecal microbiota and related clinical indicators in ICU patients with sepsis

BackgroundTo analyze the characteristics of fecal microbiota disturbance in the intensive care unit (ICU) patients with sepsis and the correlation with related clinical indicators. MethodsThis study included 31 patients with sepsis admitted to the emergency ICU ward between September 2019 and December 2021. They were divided into Group without septic shock (ND_NS group, 7 cases) and Group with septic shock (ND_S group, 24 cases) according to the presence or absence of septic shock. Furthermore, we divided these 31 sepsis patients into Clinical Improvement group (21 cases) and Death or DAMA group (10 cases) based on clinical outcome, 15 cases of Physical Examiner recruited in the same period were included as control group: ND_HC group (15 cases). The fecal samples of the patients with sepsis within 24 h of admission and random fecal samples of the control group were collected and analyzed by 16S rDNA gene sequencing used for the analysis of fecal microbiota. At the same time, the relevant clinical data of these patients with sepsis were also collected for analysis. ResultsThere were 15 cases with drug-resistant bacteria in the ND_S group and only 2 cases in the ND_NS group (P = 0.015). There were significant differences in APACHE II score, length of ICU stay, lactate level, and oxygenation index of patients between the Death or DAMA group and Clinical Improvement group (all P < 0.05). For phylum level, the abundance of Firmicutes, Actinobacteria, and Bacteroidetes decreased in the ND group compared with the ND_HC group, while the abundance of Proteobacteria increased (P < 0.05). For genus level, the relative abundance of Escherichia-Shigella and Klebsiella were significantly increased in the ND group compared with the ND_HC group (P < 0.05). The top six genera in relative abundance in the ND_S group were Escherichia-Shigella, Enterococcus, Bifidobacterium, Lactobacillus, Akkermansia, and Klebsiella. Compared with the Clinical Improvement group, the relative abundance of Escherichia-Shigella and Klebsiella in the Death or DAMA group showed an increasing trend with no significant significance, while the relative abundance of Enterococcus and Faecalibacterium decreased in the Death or DAMA group (P < 0.05). Alpha diversity analysis showed that compared with the ND_HC group, the alpha diversity of the fecal microbiota in the ND group decreased. There were significant differences in the Observed_species index, Chao1 index, and ACE index of patients between the ND_HC group and ND group (all P < 0.05). Moreover, compared with the ND_NS group, the Alpha diversity of the ND_S group was more abundant. PCoA analysis showed significant differences in microbial community structure between the ND group and ND_HC group (P = 0.001). There also were significant differences in microbial community structure between the ND_S group and ND_NS group (P = 0.008). LEfSe analysis showed that compared with the ND_HC group, there were significant differences in the species of the ND group, including Enterobacteriaceae, Escherichia-Shigella, Enterococcus, Elizabethkingia, and Family_XIII_AD3011_group. ConclusionsICU patients with sepsis suffered intestinal microecological disturbances with significantly decreased abundance of fecal microbiota, diversity, and beneficial symbiotic bacteria. For these patients, the ratio of pathogenic bacteria, including Escherichia-Shigella and Klebsiella increased and became the main bacterial genus in some samples. Moreover, the increasing trend of these two pathogenic bacteria may be correlated with the development of septic shock and the risk of death in patients with sepsis.

Novel coarse and fine stage parallel vibration isolation pointing platform for space optics payload

A coarse and fine parallel vibration isolation pointing platform (CFPP) is proposed, which can realize a wide range of motion and active vibration isolation for space optical payload. First the coarse and fine parallel connection scheme is designed based on the Stewart generalized configuration. Kinematic and constraint analyses are performed to determine the two operation modes of the platform. The platform is then structurally designed. System dynamics model is established based on the Lagrange method, and the dynamic disturbance characteristics are analyzed. Next, the active vibration isolation control algorithm based on H∞ loop shaping is designed. The stability of the control system is analyzed. Finally, the prototype is constructed, and the three-axis pointing range test and active vibration isolation experiments in four attitudes are carried out, and the experimental results show that the designed pointing vibration isolation system with coarse and fine stages in parallel can achieve a 7° movement range of the three axes, and it has a maximum vibration isolation capacity of 20 dB for the disturbance in the frequency band of 2–20 Hz. It has great application prospects in the direction of miniaturization and integration of space optical payload in the future.

Negative life events and sleep disturbance among adolescents: Intolerance of uncertainty as mediator and moderator

BackgroundWhile negative life events (NLEs) have been linked to an increased risk of sleep disturbance among adolescents, the mechanisms of this impact still lack further examination. The current study aimed to explore whether intolerance of uncertainty (IU), a dispositional transdiagnostic vulnerability factor for psychopathology, could act as a mediator and/or moderator in the link from NLEs to sleep disturbance. MethodsA longitudinal nested subsample of 54,240 Chinese adolescents (aged 9–19) were surveyed at baseline (Timepoint 1) and six months later (Timepoint 2). They completed questionnaires to assess their IU, NLEs, sleep disturbance and sociodemographic characteristics. Mediation and moderation analyses were conducted to test our hypotheses. ResultsUpon adjusting for covariates, IU was found to mediate the relationship between NLEs and residual changes in sleep disturbance over a six-month period, with the mediation effect accounting for 31.8%. Additionally, the moderating role of IU in this relationship was also identified, suggesting that a high level of IU exacerbated the effect of NLEs on sleep disturbance. ConclusionsIn conclusion, our findings shed light on the dual roles of IU in the link from NLEs to sleep disturbance, holding significant practical implications for preventing and intervening in sleep disturbance among adolescents. To mitigate the risk of sleep disturbance among adolescents experiencing NLEs, timely assessments of IU and tailored interventions to enhance uncertainty tolerance are necessary.

Menstrual abnormalities effects on clinical features and in vitro fertilization pregnancy outcomes in women with polycystic ovarian syndrome

The diagnostic criteria and phenotypes in polycystic ovary syndrome are heterogeneous. Currently, it is unclear how to assess a patient's prognosis based on the onset time of menstruation disturbance. Evidence on this topic is scarce and has mainly focused on menstrual patterns. This study aimed to assess the association between the onset time of menstrual disturbance and clinical features and in vitro fertilization pregnancy outcomes in patients with polycystic ovary syndrome. Our study was a secondary analysis of data collected as part of a randomized controlled trial conducted to compare live birth rates between fresh embryo transfer and frozen embryo transfer in 1508 individuals with polycystic ovary syndrome. Here, 1500 participants were classified into 2 groups according to the onset time of menstrual disturbance: immediately after menarche (early group) and after at least 1 year of regular menstruation (late group). We compared the prepregnancy clinical features, variables of ovarian stimulation, pregnancy outcomes after the initial cycle of embryo transfer, and perinatal and neonatal complications in the 2 groups. Compared with the late group, the early group had more antral follicles (32.00 [range, 27.25-39.50] vs 28.00 [range, 24.00-36.00]; P<.001), an elevated level of antimüllerian hormone (7.02 ng/mL [range, 3.60-11.47] vs 5.66 ng/mL [range, 3.65-8.92]; P=.024), a higher level of baseline luteinizing hormone (10.01±5.93 vs 8.51±5.53 IU/l; P<.001) and luteinizing hormone-to-follicle-stimulating hormone ratio (1.51 [range, 1.00-2.32] vs 1.45 [range, 0.92-2.13]; P<.001), lower levels of fasting glucose (5.47 mmol/L [range, 5.11-5.73] vs 5.50 mmol/L [range, 5.17-5.76]; P<.001), and insulin at 2 hours after 75-g oral glucose tolerance test (56.85 µU/mL [range, 34.63-94.54] vs 59.82 µU/mL [range, 33.56-94.67]; P=.027), a higher level of high-density lipoprotein (1.26 mmol/L [range, 1.04-1.37] vs 1.21 mmol/L [range, 1.07-1.45]; P=.006). During in vitro fertilization, the early group had a higher level of peak estradiol (4596.50 pg/mL [range, 2639.25-6321.00] vs 3954.00 pg/mL [range, 2378.75-6113.50]; P=.013), and luteinizing hormone (2.52 IU/L [range, 1.40-4.21] vs 1.93 IU/L [range, 0.91-3.32]; P=.010) on the day of human chorionic gonadotropin trigger. There was no statistically significant difference observed in the number of oocytes and embryos, the rates of pregnancy and live birth, and the risks of obstetrical and neonatal between the 2 groups. An early onset of menstrual disturbance in patients with polycystic ovary syndrome may be associated with slightly more severe reproductive features and slightly milder metabolic features. Nonetheless, the outcomes of in vitro fertilization and the initial cycle of embryo transfer were comparable between the 2 groups.

Erasing anthropogenic disturbance: Natural revegetation of linear features following wildfire, and the implications for woodland caribou (Rangifer tarandus caribou) habitat management.

The federal recovery strategy for woodland caribou identifies wildfires within the last 40 years and anthropogenic disturbance visible at a scale of 1:50,000, including a 500-m buffer, as disturbed. Long-term vegetation recovery on linear features post-fire has not yet been documented. We examined vegetation recovery including stem density and height, hiding cover, and reindeer lichen cover along 40+ year-old legacy linear features in Northern Saskatchewan, in both uplands and lowlands 1–41 years post-fire. We compared these results with burned areas off-lines and unburned lines. On unburned lines in uplands there was minimal recovery, while there was significant recovery of stem count, height and hiding cover on burned lines and burned off-lines. Reindeer lichen cover and thickness remained significantly lower on burned lines and burned off-lines than on unburned lines until the 41-year age group, where there was no longer a significant difference. In lowlands, the stem density and stem height were initially significantly higher on unburned lines than on either burned lines or burned off-lines. After 27–32 years post-fire there was no longer a significant difference in stem densities. Our findings show that fires substantially accelerate natural revegetation and instigate a recovery that is similar on and off disturbance features in both uplands and lowlands. These findings can inform management decisions on restoration planning and calculation of range disturbance metrics. We suggest that the anthropogenic 500-m buffer should be removed post fire, as anthropogenic disturbance is reset, and anthropogenic disturbance should be classified as naturally recovering.

The complex unsteady flow exploration of a contra-rotating rotor under inlet distortion

This article explores the relationship between stall types and speed ratios in contra-rotating boost stages, discovering stationary circumferential stall cells and dual stall cell phenomena, and examines the relationship between stall characteristics and inlet distortions. These stall characteristics of counter-rotating boost stages are markedly different from the single stall patterns of traditional compressor rotor-stator structures, highlighting the complexity of the flow field in counter-rotating stages. The study uses the experimental methods to investigate different speed ratios under both uniform and distorted inlet conditions, conducting both accelerating and decelerating stall tests, with each stall condition analyzed using data from 25 s. The main focus is on the stall types, frequencies, and development patterns under different distortion conditions at various speed ratios, filling a research gap in counter-rotating boost stages. It explores the unstable flow characteristics of counter-rotating boost stages under distorted conditions, particularly the stall disturbance characteristics and pressure fluctuation patterns at the blade tip during stall entry and recovery under distortions. Comparing distortions with uniform inlet conditions provides an intuitive understanding of the influence of various types of distortions on wall pressure and stall in the flow field. Researchers can use this knowledge to design casings or blowing devices to suppress stall disturbances, thereby achieving stall prevention and enhancing stability.

Impact of Climate Change on the Distribution of Three Rare Salamanders (Liua shihi, Pseudohynobius jinfo, and Tylototriton wenxianensis) in Chongqing, China, and Their Conservation Implications.

The Wushan Salamander (Liua shihi), Jinfo Salamander (Pseudohynobius jinfo), and Wenxian Knobby Salamander (Tylototriton wenxianensis) are rare national Class II protected wild animals in China. We performed MaxEnt modeling to predict and analyze the potential distribution and trends of these species in Chongqing under current and future climate conditions. Species distribution data were primarily obtained from field surveys, supplemented by museum collections and the existing literature. These efforts yielded 636 records, including 43 for P. jinfo, 23 for T. wenxianensis, and 570 for L. shihi. Duplicate records within the same 100 m × 100 m grid cell were removed using ENMTools, resulting in 10, 12, and 58 valid distribution points for P. jinfo, T. wenxianensis, and L. shihi, respectively. The optimization of feature class parameters (FC) and the regularization multiplier (RM) were applied using R package "ENMeval 2.0" to establish the optimal model with MaxEnt. The refined models were applied to simulate the suitable distribution areas for the three species. The results indicate that the current suitable habitat area for L. shihi accounted for 9.72% of the whole region of the Chongqing municipality. It is projected that, by 2050, the proportion of suitable habitat will increase to 12.54% but will decrease to 11.98% by 2070 and further decline to 8.80% by 2090. The current suitable habitat area for P. jinfo accounted for 1.08% of the whole region of the Chongqing municipality, which is expected to decrease to 0.31%% by 2050, 0.20% by 2070, and 0.07% by 2090. The current suitable habitat area for T. wenxianensis accounted for 0.81% of the whole region of the Chongqing municipality, which is anticipated to decrease to 0.37% by 2050, 0.21% by 2070, and 0.06% by 2090. Human disturbance, climate variables, and habitat characteristics are the primary factors influencing the distribution of three salamander species in Chongqing. The proximity to roads significantly impacts L. shihi, while climate conditions mainly affect P. jinfo, and the distance to water sources is crucial for T. wenxianensis. The following suggestions were made based on key variables identified for each species: (1) For L. shihi, it is imperative to minimize human disturbances and preserve areas without roads and the existing vegetation within nature reserves to ensure their continued existence. (2) For P. jinfo, the conservation of high-altitude habitats is of utmost importance, along with the reduction in disturbances caused by roads to maintain the species' ecological niche. (3) For T. wenxianensis, the protection of aquatic habitats is crucial. Additionally, efforts to mitigate the impacts of road construction and enhance public awareness are essential for the preservation of this species and the connectivity of its habitats.

Forbush decreases and geomagnetic disturbances: 2. Comparison of solar cycles 23–24 and events with sudden and gradual onset

Statistical relationships between the values of geomagnetic indices and the characteristics of cosmic rays and interplanetary disturbances are studied for Forbush decreases with sudden and gradual onset associated with different types of solar sources: a) coronal mass ejections from active regions accompanied by solar flares; b) filament eruptions outside active regions; c) high-speed streams from coronal holes; d) several sources. Using statistical methods, the dependence of geomagnetic indices on cosmic ray and solar wind parameters for Forbush decreases in solar cycles 23 and 24 is also compared. The results obtained showed: a) interplanetary disturbances associated with coronal mass ejections from active regions cause mainly magnetic storms with a sudden onset; b) interplanetary disturbances associated with high-speed streams from coronal holes cause mainly storms with a gradual onset; c) interplanetary disturbances associated with filament eruptions outside active regions cause equally probable storms with a sudden and gradual onset. For sporadic Forbush decreases the values of cosmic ray and geomagnetic activity parameters are, on average, higher for events with a sudden onset; for recurrent Forbush decreases, the nature of the event onset does not affect the value of these parameters. For all types of solar sources the parameters of the disturbed solar wind are, on average, higher in events with a sudden onset. The geoefficiency of interplanetary disturbances is much higher in the 23rd cycle for events associated with ejections from active regions; for other types of disturbances, the difference between the cycles is weak.

Synergistic effects of anthropogenic disturbances on giant pandas

AbstractLivestock grazing and the collection of bamboo shoots are the main threats to giant panda (Ailuropoda melanoleuca) habitat in the Liangshan Mountains in China. It is important to clarify the effect of these disturbances to the giant panda to formulate targeted management policies. Based on species distribution models and daily activity models, we investigated the effects of livestock grazing and bamboo shoot collection on giant pandas from May 2021 to July 2022. Our results indicated the giant panda's suitable habitat in the reserve covered 51.83 km2 (15.02% of the reserve area). Grazing and bamboo shoot collection led to losses of 19.08 km2 and 7.68 km2 of suitable habitat, respectively. Together, the 2 activities resulted in a loss of 28.35 km2 of suitable habitat, which was more than half of the area of panda habitat. The areas of suitable habitat for giant pandas significantly overlapped with the areas affected by both disturbances. Giant pandas did not show significant differences in daily activity rhythms under a single disturbance, but the daily activity rhythms of giant pandas differed when we compared the area combining the 2 disturbances with the undisturbed area. Our study reveals that the anthropogenic disturbances in the reserve have varying effects on the suitable habitat range and daily activity rhythm of giant pandas and evidence of a synergistic effect. Therefore, when formulating relevant conservation policies, it is important to fully evaluate the extent and characteristics of anthropogenic disturbances in shaping the population distribution and habitat preferences of the giant panda and other wildlife to enhance the efficacy of conservation management practices.

Structural and socioeconomic features of cities predict migratory bird species richness

Cities are aggregates of human activities where our decisions shape the environment creating heterogeneity across urban centers that can have significant ecological effects on wildlife. Many bird species are found in cities during the breeding season, which implies they find sufficient resources in cities to support them during this energetically costly time. As populations of many migratory bird species are declining, knowledge of how they are affected by urbanization is needed. Yet, we know little about how the species richness of migratory birds varies across different types of cities. Here we ask if cities' structural and socioeconomic features can predict the species richness of migratory birds that generally select different breeding habitats during the breeding season. We used eBird data from census‐designated urban areas in the US to model the relationship between features of cities (housing density, median income, city age, and commuting time), environmental disturbance (measured by the human footprint index) and species richness by fitting generalized linear models to data. We show that commuting time was the most important factor determining species richness across cities and the rest of the city features were weakly associated with species richness. Overall species were responding to city variation in similar ways. While we expected that cities with more disturbance would have lower species richness, our results indicate that some species are able to tolerate even highly disturbed cities and that cities in certain regions may act as a refuge to birds. This knowledge is important for our general understanding of cities as habitat for birds and how migratory birds respond to across‐city variation during the breeding season.

Simulation of Draught Reduction Performance of Subsoiling with Upcutting Belt Motion Using Discrete Element Method

Conventional subsoiling has the problem of excessive draught resistance, which has long been a major concern. A great reduction in draught is urgently required to make better use of the subsoiling technique with many agronomic benefits. In this study, an attempt was made to test the draught reduction performance of a series of tools with continuous belt motions. Comparative simulations between regular tools and belt tools were carried out using the discrete element method (DEM) to investigate the effects of belt motion on tool force, soil disturbance characteristics, particle velocity distribution, and soil deformation and movement patterns. The results indicated that the belt motion reduced the draught force by 13.18%, 25.21%, 37.98%, and 44.64% for the rake angles of 30°, 45°, 60°, and 75°, respectively, and caused acceptable increases in downward vertical force. The changes in soil disturbance, particle velocity distribution, and soil deformation and movement patterns contributed to the reduction in draught force. Negative effects on soil disturbance were acceptable considering the 13.18% to 44.64% reductions in draught force. The present study suggests that the belt motion has a great application potential for draught reduction in subsoiling. Also, this can serve as a theoretical foundation for future studies.