Cyclic Phenomena Research Articles

Low cycle fatigue behavior and failure mechanism of 34CrNiMo6 steel used as connecting rod for diesel engine

Abstract In this paper, for the 34CrNiMo6 steel material used in diesel engine connecting rods, the low-cycle fatigue properties and failure mechanism were studied. The metallographic structure of 34CrNiMo6 has been investigated by using optical microscopes, scanning electron microscopes, and transmission electron microscopes. Tensile tests and low-cycle fatigue experiments were performed at different levels of strain amplitudes, and the microstructural changes were monitored. The examination indicates that the structure of 34CrNiMo6 steel consisted primarily of a ferrite base and small spherical and rod-shaped carbides, with a mean particle size measuring 2 μm. It had exceptional mechanical characteristics of high strength and moderate plasticity. The total strain amplitude (TSA) of 34CrNiMo6 steel affected the cycling behavior, which was stable at low TSA (0.2% ~ 0.3%). At high TSA (0.4% ~ 0.7%), a large number of dislocations were annihilated through the dynamic recovery process, showing a typical cyclic softening phenomenon. The low-cycle fatigue failure behavior was mainly a combined mode of quasi-cleavage fracture and cross-grain fracture.

Understanding the Role of Layered Minerals in the Emergence and Preservation of Proto-Proteins and Detection of Traces of Early Life.

ConspectusThe origin of life remains one of the most profound mysteries in science. Over millennia, theories have evolved, yet the question persists: How did life emerge from inanimate matter? At its core, the study of life's origin offers insights into our place in the universe and the nature of life itself. By delving into the chemical and geological processes that led to life's emergence, scientists gain a deeper understanding of the fundamental principles that govern living systems. This knowledge not only expands our scientific understanding but also has profound implications for fields ranging from astrobiology to synthetic biology.This research employs a multidisciplinary approach, combining a diverse array of techniques, from space missions to wet laboratory experiments to theoretical modeling. Investigations into the formation of the first proto-biomolecules are tailored to explore both the complex molecular processes that underpin life and the geological contexts in which these processes may have occurred. While laboratory experiments are aimed at mimicking the processes of early planets, not every process and sample is attainable. To this end, we demonstrate the use of molecular modeling techniques to complement experimental efforts and extraterrestrial missions. The simulations enable researchers to test hypotheses and explore scenarios that are difficult or impossible to replicate in the laboratory, bridging gaps in our understanding of prebiotic processes across vast time and space scales.Minerals, particularly layered structures like clays and hydrotalcites, play diverse and pivotal roles in the origin of life. They concentrate organic species, catalyze polymerization reactions (such as peptide formation), and provide protective environments for the molecules. Minerals have also been suggested to have acted as primitive genetic materials. Nevertheless, they may lack the ability for long-term information replication. Instead, we suggest that minerals may act as transcribers of information encoded in environmental cyclic phenomena, such as tidal or seasonal changes. We argue that extensive protection of the produced polymer will immobilize it, making it inactive for any further function. Therefore, in order to generate a functional polymer, it is essential that it remains mobile and chemically active. Furthermore, we suggest a route to the identification of pseudobiosignatures, a polymer that was polymerized on the same mineral surface and consequently retained through overprotection.This Account presents a comprehensive evaluation of the current understanding of the role of layered mineral surfaces on life's origin and biosignature preservation. It highlights the complexity of mineral-organic interactions and proposes pathways for proto-biomolecule emergence and methods for identifying and interpreting potential biosignatures. Ultimately, the quest to uncover the origin of life continues to drive scientific exploration and innovation, offering profound insights into the fundamental nature of existence and our place in the universe.

Optimization of wind farm energy supply system costs through machine learning

At present, the energy crisis is becoming increasingly severe, and changing the energy structure and developing clean energy have gradually become the consensus of the world. Establishing a clean energy power supply system, using clean energy for power generation, and investing in real power supply are currently unresolved challenges. Based the current high cost of new energy power supply systems, this project proposes an optimization plan based on the wind power supply system, targeting the capacity of lithium battery energy storage equipment, and constructs an optimization model for wind power supply in electric vehicle systems. In addition, in order to use lithium-ion battery devices more efficiently and ensure the evaluation of the efficiency and battery life of lithium-ion battery energy storage devices, we predicted the cyclic aging phenomenon of lithium-ion battery energy storage devices through machine learning technology. This prediction can provide suggestions and references for the use of this lithium battery.

On the development of a constitutive model for steel subjected to fire and explosion

The behavior of steel under thermal and mechanical loading including high transient temperatures and strain rates (e.g., fire, creep or explosion) is extremely complex. To study this behavior, we propose a constitutive model accordance with the laws of thermodynamic, the principle of virtual power and experimental results. The thermodynamic framework considers the Clausius-Duhem inequality and maximum dissipation rate principle, as well as the theory of finite deformations, linear isotropic viscoelasticity, nonlinear isotropic and kinematic hardening, local and non-local viscoplasticity, local and non-local anisotropic viscodamage and parameters associated to material behavior dependent on loadings. The components of the thermodynamic conjugate forces are defined from the Helmholtz free energy function and the rate of energy dissipation, which are postulated considering the creep phenomenon, thermal-mechanical transient phenomenon, cyclic phenomenon and plastic wave propagation phenomenon. The balance of microforces is defined based on the principle of virtual power. A novel rule of non-associated thermo-viscoplastic flow of the Perzyna type and a novel rate dependent local and non-local damage evolution law are introduced from constitutive model. The verification of the model was carried out in two benchmark studies composed of fire tests. The predictions of the model have shown in according with the results of the experiments. A sensitivity study was also performed with a view to analysis the influence of the parameters in achieved results. From this study a simplified constitutive model is presented. Benchmark studies composed of explosion tests are part of future work.

VERIFICATION OF LAMINATE COMPOSITEPLATE SIMULATION UNDER COMBINED LOADINGS THERMALSTRESSES

This study deals with thermal cyclic loading phenomena of plates which were fabricated from composite materials (woven roving fiber glass + polyester) were exposed to (75 C°) temperature gradient thermal shock for ten times in different stage of conditioning times due to the effect of thermal fatigue using the method of Levy solution and compared these results with both results from experimental published work and (ANSYS Ver. 9) program. A composite laminate plate with fiber volume fraction (υf =25.076%) is selected in this study and applying the combined loadings like bending moment (Mo), and in-plane force (Nxx) beside the effect of thermal fatigue. It involves multi theoretical and finite element fields; but the theoretical one contains the derived equation of stresses distribution and evaluating the normal deflection of a middle point for dynamic analysis applying different boundary conditions for heating and cooling. The main present numerical results for a composite plate with (80%) fiber volume fraction claim that the relative reduction in normal deflection and dynamic load factor are (78.593%) and (9.421%) during cooling to (-15 respectively.

Enhancing ENSO predictions with self-attention ConvLSTM and temporal embeddings

El Niño-Southern Oscillation (ENSO), a cyclic climate phenomenon spanning interannual and decadal timescales, exerts substantial impacts on the global weather patterns and ecosystems. Recently, deep learning has brought considerable advances in the accurate prediction of ENSO occurrence. However, the current models are insufficient to characterize the evolutionary behavior of the ENSO, particularly lacking comprehensive modeling of local-range and longrange spatiotemporal interdependencies, and the incorporation of calendar monthly and seasonal properties. To make up this gap, we propose a Two-Stage SpatioTemporal (TSST) autoregressive model that couples the meteorological factor prediction with ENSO indicator prediction. The first stage predicts the meteorological time series by leveraging self-attention ConvLSTM network which captures both the local and the global spatial-temporal dependencies. The temporal embeddings of calendar months and seasonal information are further incorporated to preserves repeatedly-occurring-yet-hidden patterns in meteorological series. The second stage uses multiple layers to extract higher level of features from predicted meteorological factors progressively to generate ENSO indicators. The results demonstrate that our model outperforms the state-of-the-art ENSO prediction models, effectively predicting ENSO up to 24 months and mitigating the spring predictability barrier.

Interface‐Driven Spontaneous Differentiation‐Repulsion Behavior in Isochemical Droplet Populations

AbstractAn important exercise for understanding the emergent behavior in biology is to study it using minimal synthetic systems. Current biomimetic systems involving directed motion and collective migration require at least three components: two immiscible solvents to form an emulsion, and external agent(s), usually surfactants, to give rise to asymmetric interactions and induce transient non‐equilibrium conditions. Here, the most minimal system thinkable, consisting of only two components, is presented, in the form of micron‐sized oil (1‐decanol) droplets dispersed in a finite water reservoir. Spontaneous emergent dynamics within chemically identical droplet populations is reported, in the form of physical differentiation of droplets in a stochastic manner leading to an immediate repulsive behavior amongst their neighbors. Using a microfluidic production platform, fluorescence microscopy experiments, and modelling, it is showed that this cyclic phenomenon of differentiation‐repulsion results from oil droplets entering the air‐water interface leading to Marangoni flows and their coupling with evaporative flux of decanol. The potential of this platform is illustrated by demonstrating control over the event frequency, its use as Marangoni tweezers to trap droplet clusters, and proof‐of‐principle reorganization of multi‐component assemblies. The presented collective behavior with exceptional chemical simplicity makes it amenable for potentially developing self‐assembled biomimetic and bioengineered structures.

Effects of Episodic Food Insecurity on Psychological and Physiological Responses in African American Women With Obesity (RESPONSES): Protocol for a Longitudinal Observational Cohort Study.

Food insecurity is a risk factor for multiple chronic diseases, including obesity. Importantly, both food insecurity and obesity are more prevalent in African American women than in other groups. Furthermore, food insecurity is considered a cyclic phenomenon, with episodes of food adequacy (ie, enough food to eat) and food shortage (ie, not enough food to eat). More research is needed to better understand why food insecurity is linked to obesity, including acknowledging the episodic nature of food insecurity as a stressor and identifying underlying mechanisms. The objective of this study is to investigate the episodic nature of food insecurity as a stressor via responses in body weight and psychological and physiological parameters longitudinally and do so in a health-disparate population-African American women. We enrolled 60 African American women (food-insecure cohort: n=30, 50%; food-secure cohort: n=30, 50%) aged 18-65 years with obesity (BMI 30-50 kg/m2) to measure (1) daily body weight remotely over 22 weeks and (2) psychological and physiological parameters via clinic assessments at the beginning and end of the 22-week study. Furthermore, we are assessing episodes of food insecurity, stress, hedonic eating, and appetite on a weekly basis. We hypothesize that food-insecure African American women with obesity will demonstrate increased body weight and changes in psychological and physiological end points, whereas food-secure African American women with obesity will not. We are also examining associations between changes in psychological and physiological parameters and changes in body weight and performing a mediation analysis on the psychological parameters assessed at the study midpoint. Psychological questionnaires are used to assess stress; executive function, decision-making, and motivation; and affect and nonhomeostatic eating. Physiological measurements are used to evaluate the levels of cortisol, dehydroepiandrosterone-sulfate (DHEA-S), C-reactive protein, thyroid hormones, blood glucose, glycated hemoglobin, and insulin, as well as allostatic load. This study has completed participant recruitment (n=60). At the time of study enrollment, the mean age of the participants was almost 47 (SD 10.8) years, and they had a mean BMI of 39.6 (SD 5.31) kg/m2. All data are anticipated to be collected by the end of 2023. We believe that this is the first study to examine changes in body weight and psychological and physiological factors in food-insecure African American women with obesity. This study has significant public health implications because it addresses the cyclic nature of food insecurity to identify underlying mechanisms that can be targeted to mitigate the adverse relationship between food insecurity and obesity and reduce health disparities in minority populations. ClinicalTrials.gov NCT05076487; https://clinicaltrials.gov/study/NCT05076487. DERR1-10.2196/52193.

Lake Avernus Has Turned Red: Bioindicator Monitoring Unveils the Secrets of "Gates of Hades".

Lake Avernus is a volcanic lake located in southern Italy. Since ancient times, it has inspired numerous myths and legends due to the occurrence of singular phenomena, such as coloring events. Only recently has an explanation been found for them, i.e., the recurring color change over time is due to the alternation of cyanobacterial blooms that are a consequence of natural nutrient inputs as well as pollution resulting from human activities. This current report specifically describes the red coloring event that occurred on Lake Avernus in March 2022, the springtime season in this region of Italy. Our innovative multidisciplinary approach, the 'Fast Detection Strategy' (FDS), was devised to monitor cyanobacterial blooms and their toxins. It integrates remote sensing data from satellites and drones, on-site sampling, and analytical/bioinformatics analyses into a cohesive information flow. Thanks to FDS, we determined that the red color was attributable to a bloom of Planktothrix rubescens, a toxin-producing cyanobacterium. Here, we report the detection and identification of 14 anabenopeptins from this P. rubescens strain, seven of which are known and seven are newly reported herein. Moreover, we explored the mechanisms and causes behind this cyclic phenomenon, confirming cyanobacteria's role as reliable indicators of environmental changes. This investigation further validates FDS's effectiveness in detecting and characterizing cyanobacterial blooms and their associated toxins, expanding its potential applications.

Numerical study of the unsteady blade root aerodynamics of a 2 MW wind turbine equipped with vortex generators

Abstract. In order to design vortex generators for modern multi-megawatt wind turbines accurately, the 3D behaviour of the boundary layer has to be considered. Due to the rotation of the blade, the lift-enhancing rotational augmentation has a considerable impact, especially in the inner blade sections. To investigate the interaction of vortex generators and rotational augmentation, high-fidelity computational flow simulations by means of unsteady Reynolds-averaged Navier–Stokes methods are presented for a rotating blade of a generic 2 MW horizontal-axis wind turbine. The inner blade section is analysed with and without vortex generators for two different pitch settings, including one causing largely separated flow. Two ways of placing the vortex generators on the blade with different radial starting positions are investigated in order to find out if the coexistence of the two lift-enhancement methods (i.e. rotational augmentation and vortex generators) is beneficial. All simulations are performed with the flow solver FLOWer, and the vortex generators are modelled by the introduction of source terms into the computational domain through a so-called BAY (Bender–Anderson–Yagle)-type model. For the case without vortex generators, it is found that the strength of rotational augmentation largely depends on the effective angles of attack (i.e. the pitch setting). For the case with lower effective angles of attack, rotational augmentation is a cyclic phenomenon, whereas for the case with higher effective angles of attack, it generates large loads in the inner root section due to a constant centrifugal pumping mechanism in time. The results from the cases with vortex generators display a rather destructive interaction of vortex generators and rotational augmentation on the torque. For low effective angles of attack and thus attached flow conditions, vortex generators exhibit slight losses compared to the case without vortex generators, as they inhibit spanwise flow through rotational augmentation. For high effective angles of attack, the vortex generators placed over 30 % of the blade produce an increase of 3.28 % in torque compared to the case without vortex generators and high centrifugal pumping.

Promotion and growth diagrams for fans of Dyck paths and vacillating tableaux

We construct an injection from the set of r-fans of Dyck paths (resp. vacillating tableaux) of length n into the set of chord diagrams on [n] that intertwines promotion and rotation. This is done in two different ways, namely as fillings of promotion matrices and in terms of Fomin growth diagrams. Our analysis uses the fact that r-fans of Dyck paths and vacillating tableaux can be viewed as highest weight elements of weight zero in crystals of type Br and Cr, respectively, which in turn can be analyzed using virtual crystals. On the level of Fomin growth diagrams, the virtualization process corresponds to the Roby–Krattenthaler blow up construction. One of the motivations for finding rotation invariant diagrammatic bases such as chord diagrams is the cyclic sieving phenomenon. Indeed, we give a cyclic sieving phenomenon on r-fans of Dyck paths and vacillating tableaux using the promotion action.

Strategies to improve metal-organic frameworks and their derived oxides as lithium storage anode materials

Lithium-ion batteries (LIBs) are widely used as energy storage technology in emerging markets such as electric vehicles. The development of anode materials that can replace graphite materials is a hotspot of current research. Metal-organic frameworks (MOFs), as a kind of important porous inorganic organic hybrid crystals, have been developed and used as anode materials for LIBs. MOFs can be used as precursors for transition metal oxides (TMOs) with nanostructures based on unique properties such as their unique structure and morphological characteristic, and controllable skeleton composition. In this review, the application and recent progress of MOFs and their derived TMOs in anode materials for LIBs are reviewed. Attention is also paid to their electrochemical mechanisms and the mechanism of the cyclic capacity enhancement phenomenon. Finally, the challenges of MOFs and their derived TMOs as LIBs anode materials are discussed, and modification strategies to improve their electrochemical performance are analyzed and summarized.

Free Action and Cyclic Sieving on Skew Semi-standard Young Tableaux

In this note, we provide a short proof of Theorem 4.3 in the paper titled Crystals, semistandard tableaux and cyclic sieving phenomenon, by Y.-T. Oh and E. Park, which concerns a cyclic sieving phenomenon on semi-standard Young tableaux. We also extend their result to skew shapes.

Fish Carboxyl Esterase Activity as a Possible Hypoxia Biomarker

Physiology and biochemistry adaptations studied in fish are important to comprehend how they endure the challenges of living in aquatic environments. Oxygen variations are a frequent natural and cyclic phenomenon that occurs in the Pantanal and Amazon watersheds and it is the limiting factor to survival of the aerobic species. The growing of pollution in these water basins threaten many species as anthropic hypoxia intensifies the production of reactive oxygen species (ROS) and lipid peroxidation inside the cells, leading organisms to a condition known as oxidative stress. Our research group, studying the effects of the oxygen variations on the carboxyl esterase (CarbE) enzyme of pacu, a typical fish from Pantanal, observed that CarbE activity diminished by half in pacus exposed to 42 hours of hypoxia. Based on this finding, we decided to investigate this phenomenon in other fish species, including hypoxia-tolerant fishes. CarbE activities were determined using p-nitrophenyl acetate (p-NPA) as a substrate. All five species of fish studied had both serum and liver CarbE activity significantly decreased. Pacus had its serum and liver activities decreased by approximately 50% under severe hypoxia.

Effect of cyclic loading phenomenon on the crush resistance of different proppants: an experimental investigation

Effect of cyclic loading phenomenon on the crush resistance of different proppants: an experimental investigation

Effect of cyclic loading phenomenon on the crush resistance of different proppants: an experimental investigation

Effect of cyclic loading phenomenon on the crush resistance of different proppants: an experimental investigation

Numerical simulation study on the mechanism of releasing ultra-deep water shallow gas by drilling pilot holes

This study proposed an operation mode that actively releases shallow gas from an ultra-deep water shallow gas reservoir by drilling pilot holes. This operation mode can help discharge underground shallow gas in advance and better guarantee the security of the subsequent drilling operation. The flow law of shallow gas in the release process was simulate according to the field data of the Shenhu area in the South China Sea to study the mechanism and feasibility of actively releasing shallow gas in ultra-deep water area. The findings of the study revealed that shallow gas and seawater driving each other behavior (DEO behavior) in the shallow gas reservoir and borehole zones (underground zone: refers to the zone comprising the borehole and shallow gas zones) existed in the early release process, and the DEO behavior exhibited an obvious cyclic phenomenon. Simultaneously, the morphological development of the shallow gas spewing into the static seawater and real seawater zones was studied to obtain a clearer understanding of the gas morphological development in seawater. Based on the above findings, further investigations revealed that the operation that released shallow gas with 8-3/8″, 9-5/8″, and 12-1/4″ pilot holes in the target field did not affect the buoyancy of the seawater or sink the platform; there was almost no fluctuation to the sea surface. This study examined and compared the shallow gas flow law and remaining shallow gas volume in the reservoir with time under the application of 8-3/8″, 9-5/8″ and 12-1/4″ pilot holes. Consequently, it found that under the condition of target field larger hole sizes exhibited lower collapsing and dispersing heights (the distance between the last shaped shallow gas bubble about to burst and the mud line) and faster shallow gas release velocity. Furthermore, a numerical simulation study on the operation mode of releasing shallow gas from an ultra-deep-water shallow gas reservoir by drilling pilot holes can provide theoretical support for subsequent shallow gas treatment decisions in ultra-deep-water drilling construction.

Molecular dynamics simulation on creep-ratcheting behavior of columnar nanocrystalline aluminum

Creep-ratcheting deformation behavior of columnar nanocrystalline (NC) Al varying in grain sizes have been studied using molecular dynamics simulations at three different temperatures (300 K, 467 K, and 653 K). The underlying deformation mechanisms of columnar NC Al for two stress ratios of ratcheting are also evaluated in this study. The highest strain accumulation and rapid hysteresis loop proliferation are attained at 653 K. The dislocation density is low at 653 K in contrast to the other two deformation temperatures. The perfect dislocations support the creep-deformation process followed by Shockley partial dislocations. It is observed that the cyclic hardening phenomenon at 300 K and the cyclic softening phenomenon at 653 K dominate during creep-ratcheting loading. The specimen fails earlier at higher temperatures owing to the change in the shape of hysteresis loops. The predominant grain boundary-based deformation mechanisms of columnar NC Al specimens are grain boundary (GB) migration, GB diffusion, GB widening, GB sliding, and GBs merging for all the deformation temperatures. The variation in the extent of deformation with respect to temperatures depends on strain accumulation in the plastic region under creep-ratcheting loading.

The Effectiveness of Telecounseling on Anxiety and Self-Care Dysmenorrhea in Young Women

Background: The menstrual period is a cyclic physiological phenomenon where several problems can arise, including irregular cycles, excessive bleeding and dysmenorrhea. Dysmenorrhea is the most common gynecological problem experienced by adolescents and one of several causes of pelvic pain that harms the quality of life and restrictions on adolescent activities. One of the preventive interventions that have been successfully implemented by health promotion programs for individuals is telecounseling. This study aims to analyze the effectiveness of telecounseling on anxiety and self-care dysmenorrhea in adolescent girls at MA Darul Ulum, Palangka Raya City.Methods: Quasi Experimental Research with pretest-posttest with control group design. The study was conducted on 42 respondents in the intervention group and 42 respondents in the control group in MA Darul Ulum, Palangka Raya City.Results: There are a significant difference in anxiety scores (p value = 0.000) and self care scores (p value = 0.044) between the intervention group and the control group. Then the decrease in anxiety score (6.71) in the intervention group was higher than the anxiety score (1.19) in the control group. The increase in self-care scores (47.85) in the intervention group was higher than the self-care scores in the control group (37.15).Conclusions: Telecounseling is effective in reducing anxiety scores and increasing self-care scores for girls with dysmenorrhea.

Skew Schur Polynomials and Cyclic Sieving Phenomenon

Let $k$ and $m$ be positive integers and $\lambda/\mu$ a skew partition. We compute the principal specialization of the skew Schur polynomials $s_{\lambda /\mu}(x_1, \ldots, x_{k})$ modulo $q^m-1$ under suitable conditions. We interpret the results thus obtained from the viewpoint of the cyclic sieving phenomenon on semistandard Young skew tableaux of shape $\lambda/\mu$. As an application, we deal with evaluations of the principal specialization of the skew Schur polynomials at roots of unity.