Separation Phenomena Research Articles

The mechanical behavior and deformation mode of multilayer composite structures based on triply periodic minimal surface elements

In this paper, the mechanical behavior and compression deformation mode of three types of composite multilayer structures based on triply periodic minimal surfaces (TPMS) were conducted through experiments and finite element analysis. The results indicate that the load-displacement curves under varying stain rates manifest a double-platform characteristic for all three structure types. The P-G four-layer structure and P-G six-layer structure have no discernible extrusion of the structural layers during compression, and the entirety of the structure displays an almost regular cubic configuration after compression. Nevertheless, local separation was observed in the extruded portion of the P-H six-layer structure after the structural deformation at higher strain rates. For the other conditions, the structure exhibited a bulge but did not display any local detachment or separation phenomena. During the deformation of the P-H six-layer structure, a dome-shaped region emerges in the first and fifth layers. The “crown” layer displays an inverted bell-shaped failure mode for the first layer structure, exhibiting downward extrusion. In contrast, the fifth layer structure displays an upward extrusion and exhibits a bell-shaped failure mode. The P-H 6-layer structure has the best energy absorption performance under quasistatic compression conditions for the P-G 4-layer, P-G 6-layer and P-H 6-layer structure. However, the energy absorption performance of the identical structure remains largely consistent across varying strain rate conditions.

Airfoil Design and Flow Analysis of a Multi-Blade Centrifugal Fan: An Experimental and Simulation Study

To overcome the technical challenges of the multi-blade centrifugal fan, such as low efficiency and insufficient total pressure, the blades of the fan were optimally designed in this study. The flow field of the multi-blade centrifugal fan with a single-arc blade and an airfoil blade was simulated and compared using Computational Fluid Dynamics (CFDs). Under steady-state conditions, the total pressure, velocity field distribution, and aerodynamic performance of a multi-blade centrifugal fan were analyzed. The numerical results showed that there were vortices, secondary flows, and boundary layer separation phenomena in the flow passage of the single-arc multi-blade centrifugal fan. Based on the lift-to-drag ratio theory of airfoil in aerodynamics, four different airfoil blades were designed for the multi-blade centrifugal fan. The study found that the lift-to-drag ratio of the airfoil blades was positively correlated with the fan efficiency; among them, the A-type airfoil exhibited the highest lift-to-drag ratio within the 0–10 degree angle of attack range. The three-dimensional simulation results indicated that, except for the initial operating point B, the A-type airfoil showed higher fan efficiency under other operating conditions, and its total pressure curve was the most stable. In addition, the use of airfoil blades effectively suppressed the aforementioned adverse flow phenomena and improved the flow within the blade passage. Experimental verification further confirmed the effect of airfoil blades on improving fan performance: compared to single-arc blades, the efficiency of the multi-blade centrifugal fan increased by 3–7% after using airfoil blades, and the upper limit of high-efficiency flow increased from 450 m3/h to 650 m3/h. Meanwhile, the total pressure and power of the airfoil fan were also significantly improved. The results of this work are significant for guiding the optimal design of the fan.

УНІВЕРСИТЕТСЬКА ОСВІТА В ІСТОРІОГРАФІЇ УКРАЇНСЬКОЇ ПЕДАГОГІЧНОЇ КОМПАРАТИВІСТИКИ: КРАЇНОЗНАВЧИЙ ВЕКТОР

The article deals with the analysis of the country studies vector of Ukrainian comparative studies on the development of higher and university education in order to identify the achievements, bottlenecks and prospects for the formation of historiography of this problem. It has been revealed the complexity, multidimensionality and interdisciplinary nature of Ukrainian historiography on the development of foreign higher and university education. Taking into account the territorial-spatial and thematic-content orientation of the research, its structure includes five conditional interrelated blocks of works that consider higher and university education: 1) as a global and regional education system; 2) in the context of the phenomena «Bologna Process/European Education Area - foreign countries – Ukraine»; 3) in certain regions (mainly European); 4) in different countries; 5) in terms of the main subject of the study. The paper identifies three stages of development of the historiographical process, which reflected the peculiarities, nature, and trends in the study of national systems of higher and university education in foreign countries: 1) the post-Soviet period (1991-2001), when their targeted study began in the mid-1990s; 2) pro-European (2002-2011/12), when the perspective of studying this problem moved to the context of understanding the process of integration of foreign countries into the European Higher Education Area; 3) country studies (since 2012), when scholars began to study foreign higher education systems as separate socio-cultural phenomena. It has been revealed a narrow country studies vector of Ukrainian comparative scholars, who focused on the study of mainly five to six national higher education systems. The author characterises the phenomenon of numerous studies that have the same subject matter: on the one hand, it is objectively determined by the research interests of the authors, on the other hand, it leads to duplication of factual material and theoretical provisions.

Investigation of transonic flows through an idealized ORC turbine vane using Delayed Detached Eddy simulations

An idealized transonic blade configuration is studied using Delayed Detached Eddy Simulations (DDES), with focus on the loss mechanisms associated with the base pressure and turbulent wake development. The working fluid is Novec649, which is commonly used in low temperature Organic Rankine Cycle (ORC) power plants. Due to the molecular complexity of the fluid, a lower pressure ratio and exit Mach number are achieved compared to an air flow through the same geometry, a phenomenon that becomes more pronounced when considering thermodynamic operating conditions that lead to stronger non-ideal gas behavior, and which is well captured by models of standard use in ORC design and analysis, such as Reynolds-Averaged Navier–Stokes (RANS) models. Overall, as the fluid isentropic exponent and the exit Mach number decrease, the losses tend to increase. When performing a breakdown of the losses, the wake region provides the dominant contribution. Unlike RANS models, the DDES resolves the largest turbulent scales in the wake region, allowing fine-detail analysis of the unsteady wake dynamics, namely vortex shedding, and its influence on the loss coefficients. In the low supersonic Mach number range considered (M2∼1–2), the vortex shedding exhibits a flapping motion in the reattachment region behind the trailing edge. The Strouhal number, classically formed with the diameter of the trailing edge, is found to increase with increasing outlet Mach number. However, when introducing a new scaling based on the neck width of the reattachment region, directly related to the shape of the recirculation bubble and the associated reattachment shocks, the Strouhal number collapses to a relatively constant value of about 0.3 in all cases. DDES also shows that, due to the large heat capacity of Novec649, temperature fluctuations in the wake are greatly reduced, leading to the suppression of the so-called energy separation phenomenon occurring in air flows. While RANS simulations capture satisfactorily the main features and global quantities of the flow, they fail in describing the flow around the trailing edge. This results in inaccurate estimates of the back pressure, which ultimately leads to an underestimation of the losses by about 20%. Unsteady RANS simulations can predict the wake unsteadiness, but do not capture the couplings between large coherent structures, the recirculation, and the shocks, also resulting in inaccurate performance predictions. Thus, the present result showcase the importance of using advanced scale-resolving simulations for improved analysis and design of ORC turbines.

Dynamic analysis in polar exploration: Fluid-structure interaction modeling of projectile colliding with floating ice during water entry

In polar resource exploration, the interaction between polar detectors and floating ice, as well as their water entry mechanisms, are crucial for ensuring effective detector operation and data collection. This study developed a fluid-structure interaction (FSI) model to simulate the water entry of the projectile in a multidegree motion state upon collision with the floating ice, and the numerical method was validated through experiments. This study analyzes the mechanisms of cavity evolution and the laws of cavity pinch-off. This analysis further explores the motion states and dynamic characteristics under the interaction between the projectile and the floating ice. Additionally, this study also considers the influence of structural parameters of the floating ice, including thickness (Lt), width (Lw), and collision position (Sd), on the water entry process. The study reveals that increasing the submergence depth of the floating ice enhances the stability between the floating ice and water, and can mitigate flow separation phenomena generated by passive motion under inertial effects. Variations in the floating ice thickness significantly affect the cavity evolution and the projectile's underwater motion state. Conversely, variations in the floating ice width notably affect the liquid level disturbances, the development of splash crowns, and the evolution of passive water entry cavities. In specific multidegree motion states, various collision positions do not alter the evolution form of water entry cavities, yet the variation in collision positions notably affects floating ice displacement. As the collision position shifts from the center to the side edge of the floating ice, both the hydrodynamic forces on the projectile and the stress on the floating ice gradually decrease, with the decrease in hydrodynamic forces being the most significant, reaching up to 58%. This study is important for enhancing multi-body fluid-structure interaction algorithms and advancing polar exploration engineering development.

A brief review on Ce and Zr-based phase-separated metallic glasses

AbstractPhase-separated metallic glasses (MGs) have attracted a lot of interest recently because they offer a unique opportunity to design composites or alloys with hierarchical microstructure at various length scales. Phase-separated MGs differ from other MGs in terms of their structure and physical properties. Though a lot of theoretical work has been done, there is still a lack of understanding regarding the mechanism underlying phase separation in MGs. In general, phase separation in many MG systems is explained on the basis of nucleation and growth or spinodal decomposition mechanisms. On the other hand, the phase separation in Ce-based MGs is examined based on changes in the electronic structure of Ce atoms. This opens up a new direction of research for delineating issues pertaining to phase separation in amorphous systems. The present brief review aims to provide a comprehensive overview of the phase separation phenomenon in Ce- and Zr-based MG systems. It is broadly divided into two sections: the first section gives a brief introduction into the phase separation in MG systems, mechanisms of phase separation, micro-structural and thermal characteristics, and advantages of phase separation. The second section discusses some of the recent work on Ce- and Zr-based phase-separated MGs with respect to their design and properties. Graphical Abstract

Computational Investigation of the Operating Mechanism of the Ranque–Hilsch Vortex Tube

Abstract The Ranque–Hilsch vortex tube is a device that splits an incoming flow into two outgoing streams, but with the peculiar property that one stream exits at a lower total temperature than the incoming flow and the other at a higher total temperature. This temperature separation is accomplished without any moving parts, electronics or external power supplied to the device. Despite the passage of nearly a century since discovery of the effect, there remains a dearth of understanding regarding the mechanism responsible for the phenomenon. In fact, the literature contains competing theories with little evidence providing support. A promising technique to discern the responsible mechanisms for the energy transfer from the ultimately cold stream to the ultimately hot stream is to define a stream tube in a computational simulation of the flow that propagates upstream from the exits such that the stream tube interface separates the hot flow from the cold flow. In this article, we apply this method to a three-dimensional, full-volume analysis of the flow within a vortex tube using a computational simulation that was thoroughly validated against experiments on a physical replica of the computational geometry. In this novel study, the integral form of the energy equation was used to quantify all forms of the energy transfer within the vortex tube. The results demonstrate that the phenomenon of temperature separation is attributable primarily to viscous work in the radial direction due to the circumferential flow, with a lesser contribution from heat transfer in the radial direction.

The Subjective Tendency of Separable Phenomenon of the Separable Words

The separation structure of separable words is a construction that functionally expresses the speaker’s subjective tendency, which is the inherent law governing the phenomenon of separation of separable words. With the deepening of linguistic research, people have also begun to recognize the importance of linguistics in communication. Language is not just about expressing propositions and narrating events, it has a deeper meaning: it can serve as the speaker’s emotions or attitude, and so on. The subjective characteristics of language are also becoming the most important aspect of verbal communication.

Investigation of bioethanol low-carbon fuel for diesel engines under idling conditions: Combustion, engine performance and emissions

In this study, the low idle operation is defined as the engine running at the lowest engine speed with a few slight loads. Idling is necessary for most vehicles, especially for buses and trucks that frequently travel long distances, as drivers often rest inside the vehicle. However, under idling conditions, weak air flow and low air-fuel ratio result in poor air to fuel mixture, ultimately causing incomplete combustion and the production of more harmful exhaust emissions. Bioethanol, as a low-carbon fuel, has great potential for application in diesel engines due to its unique properties. In this research, the influences of different diesel-bioethanol blends (BE0, BE5, BE10, BE15) on combustion and emissions of a diesel engine were investigated under idle conditions. The main results show that there was no phase separation phenomenon even up to 15% bioethanol was directly blended with diesel by volume. And adding bioethanol to diesel had no significant impact on combustion pressure peak, but it postponed the start of combustion (SOC). Surprisingly, the nitrogen oxide (NOx) and smoke were simultaneously decreased by over 52% and 78% with the intervention of bioethanol, respectively.

Hierarchical curing mechanism in epoxy/bismaleimide composites: Enhancing mechanical properties without compromising thermal stabilities

It remains a considerable challenge to enhance mechanical properties without sacrifice of thermal properties in epoxy-based materials. In this study, epoxy/bismaleimide (EP/BMI) composites were synthesized via a melting blend technique using 4,4′-diaminodiphenylsulfone as the curing agent. It is found that there is a unique hierarchical curing mechanism in EP/BMI systems, including (i) respective curing of EP and BMI monomer, (ii) copolymerization between EP prepolymer and BMI monomer, (iii) homopolymerization of EP prepolymer and BMI oligomer. Via the hierarchical copolymerization, EP and BMI are compatible without phase separation phenomenon. The copolymerization concurrently improved the composites’ resistance to deformation under stress and restricted the thermal mobility of the polymer chains upon heat. Compared to pure EP resin, EP/BMI composite (4:1) shows a flexural strength of 133.6 MPa, tensile strength of 106.4 MPa and toughness of 3.6 MJ/m3 respectively, increased by 20.7 %, 36.4 % and 45.0 %. Meanwhile, Tg and Yc were also improved by 10.3 ℃ and 12.3 % in EP/BMI composite. Furthermore, the mechanical and thermal properties of the EP/BMI composites can be efficiently tailored by curing conditions and EP:BMI molar ratios. This discovery provides a significant benchmark for the design of composite material and to expand the application horizons for both EP and BMI materials.

Learning probability distributions of sensory inputs with Monte Carlo predictive coding.

It has been suggested that the brain employs probabilistic generative models to optimally interpret sensory information. This hypothesis has been formalised in distinct frameworks, focusing on explaining separate phenomena. On one hand, classic predictive coding theory proposed how the probabilistic models can be learned by networks of neurons employing local synaptic plasticity. On the other hand, neural sampling theories have demonstrated how stochastic dynamics enable neural circuits to represent the posterior distributions of latent states of the environment. These frameworks were brought together by variational filtering that introduced neural sampling to predictive coding. Here, we consider a variant of variational filtering for static inputs, to which we refer as Monte Carlo predictive coding (MCPC). We demonstrate that the integration of predictive coding with neural sampling results in a neural network that learns precise generative models using local computation and plasticity. The neural dynamics of MCPC infer the posterior distributions of the latent states in the presence of sensory inputs, and can generate likely inputs in their absence. Furthermore, MCPC captures the experimental observations on the variability of neural activity during perceptual tasks. By combining predictive coding and neural sampling, MCPC can account for both sets of neural data that previously had been explained by these individual frameworks.

Nutation-orbit resonances: The origin of the chaotic rotation of Hyperion and the barrel instability

While numerous planetary and asteroid satellites show evidence for non-trivial rotation states, none are as emblematic as Hyperion, which has long been held as the most striking example of chaotic spin-orbit evolution in the Solar System. Nevertheless, an analytically tractable theory of the full 3D spin-orbit dynamics of Hyperion has not been developed. We derive the Hamiltonian for a spinning axisymmetric satellite in the gravitational potential of a planet without assuming planar or principal axis rotation and without averaging over the spin period. Using this model, we demonstrate the emergence of resonances between the nutation and orbital frequencies that act as the primary drivers of the spin dynamics. This analysis reveals that, contrary to long-held belief, Hyperion is not tumbling chaotically. Instead, it lies near or in a nutation-orbit resonance that is first-order in eccentricity, allowing it to rotate quasi-regularly. The most reliable observations are consistent with either nonchaotic motion or chaos that is orders of magnitude smaller than originally claimed. A separate phenomenon, the so-called barrel instability, is shown to be related to a different set of nutation-orbit resonances that generalize the planar spin-orbit resonances. Finally, we show that changes in spin states over long timescales are best understood by considering chaotic diffusion of quasi-conserved quantities.

CONCEPT OF CRISIS IN SCIENTIFIC DISCOURSE

The article examines the main approaches to the concept and content of crisis in scientific literature. The main trends in the development of the crisis and its contradictions are analyzed. It is emphasized that most crises and their understanding are the result of a combination of human errors, institutional «failures» and constant changes in the sphere of functioning of society and states. The main stages of the development of theoretical approaches regarding the concept and content of the crisis and its main derivatives are considered. It has been proven that he does not have a clear understanding of the concept and essence of the crisis; there are three main approaches to understanding the concept and content of crisis; there are several stages of development and formation of the concept and content of the crisis; for the most part, researchers give this phenomenon a positive or negative character. This is explained by the complex nature of these phenomena and insufficient attention for a long time. It is indicated that analyzing the existing definitions of the concept of «crisis», we can talk about three main approaches: a crisis is a stage of the life cycle of any system, that is, a form of its development; crisis is a turning point in the functioning of the system, which provokes any changes, regardless of the result; a crisis is a deterioration of one or more parameters of the system's functioning, which can even lead to its final disappearance. It is emphasized that the crisis is not a separate phenomenon, but a process unfolding as various factors and forces interact in an unpredictable manner; disruption of the usual daily rhythm of life; the emergence and increase of anxiety and stress in the population; potential and real threats to basic values and structural social systems. It has been proven that all views on the concept and meaning of «crisis» and related concepts are determined by the established framework of their interpretation, as well as by the theoretical and spatiotemporal relationship in which they are interpreted. The conducted research shows that in modern scientific literature there are many approaches to understanding the concepts of crisis and risk, sometimes they are even opposite to each other. In this regard, it is appropriate to generalize the existing approaches to these concepts. This will provide an opportunity to more comprehensively reveal the essence of the concepts and will help during the formation of crisis and risk management policy. The modern world is quite complex and dynamic, which leads to the appearance of an increasing number of various crises and risks. Only a thorough understanding and perception of the crisis will allow, if not to avoid them, then to get out of them with the least losses.

DISSOCIATION, SPLITTING AND COMPARTMENTALIZATION IN TRAUMA-RELATED DISORDERS

The article is devoted to the analysis of actual scientific views and theoretical research on the participation of the phenomena of dissociation, splitting, and compartmentalization in disorders associated with mental trauma, in particular, PTSD and addictions. It is shown that the understanding of the concepts of dissociation and splitting developed in parallel and that both concepts emerged from research on trauma. Empirical studies show a clear correlation between dissociation, splitting, and compartmentalization with trauma-related disorders. However, there is considerable confusion in the differentiation of these concepts: some authors use them as synonyms, other authors consider dissociation to be a more basic process underlying splitting, and some distinguish two separate types of dissociation - separation, and compartmentalization. In this article, the concept of dissociation and splitting into separate independent phenomena is chosen, where dissociation is defined as the separation of mental processes or mental systems from consciousness, and splitting is defined as the division of consciousness itself into several independent centers of self-consciousness, with the phenomenon of compartmentalization referring to a shallow level of splitting. Both dissociation and splitting can exist in the spectrum from normal to deep pathology of the (sub)psychotic level. The article analyzes how dissociation and splitting can participate in the formation of trauma-related disorders such as PTSD and addiction. In the formation of PTSD, a part of the human psyche system associated with traumatic experiences is detached from consciousness as a result of protection from unbearable experiences (dissociation). Further, due to unsuccessful attempts to integrate the trauma, a negative self-concept with feelings of shame/guilt is formed, which splits off from the core self (splitting). As a result, a triadic structure is formed: the normative Ego-state, the split traumatic Ego-state, and the dissociated traumatic Self-state. When addiction is formed based on early trauma, a dissociated self-state exists since childhood, but while using psychoactive substances, it is integrated with a state of altered consciousness, which is why a person is experiencing a state of high, similar to a miracle. In this case, a system is formed of a normative Ego state, a dissociated traumatic Self-state, and a detached addictive Ego state, which is activated exclusively in a state of altered consciousness, and during activation, integration with the dissociated Self-state occurs. This addictive integration is the real motive for the use of this group of addictive drugs. The proposed concept can be used in the psychotherapy of trauma-related disorders as a conceptualization of cases and conceptualization of loci of therapeutic contact. Keywords: dissociation, splitting, compartmentalization, mental trauma, PTSD, addiction

Atomic cluster expansion interatomic potential for defects and thermodynamics of Cu–W system

The unique properties exhibited in immiscible metals, such as excellent strength, hardness, and radiation-damage tolerance, have stimulated the interest of many researchers. As a typical immiscible metal system, the Cu–W nano-multilayers combine the plasticity of copper and the strength of tungsten, making it a suitable candidate for applications in aerospace, nuclear fusion engineering, and electronic packaging, etc. To understand the atomistic origin of the defects (e.g., vacancies, free surfaces, grain boundaries, and stacking faults and thermodynamical properties), we developed an accurate machine learning interatomic potential for Cu–W based on the atomic cluster expansion (ACE) method. The Cu–W ACE potential can faithfully reproduce the fundamental properties of Cu and W predicted by density functional theory (DFT) calculations. Moreover, the thermodynamical properties, such as the melting point, coefficient of thermal expansion, diffusion coefficient, and equation of the state curve of the Cu–W solid solution, are calculated and compared against DFT and experiments. Monte Carlo molecular dynamics simulations performed with the Cu–W ACE potential predict the experimentally observed phase separation and uphill diffusion phenomena. Our findings not only provide an accurate ACE potential for describing the Cu–W immiscible system but also shed light on understanding the atomistic mechanism during the Cu–W nano-multilayers formation process.

Numerical investigation on the impact of aerodynamic braking plates positioned at streamlined sections on the slipstream and wake flow of the high-speed train based on train-fixed reference frame

This paper studies the aerodynamic characteristics of high-speed trains (HSTs) featuring aerodynamic braking plates installed on the streamlined sections, employing the improved delayed detached eddy simulation (IDDES) method at Re = 5.0 × 105. The precision of the numerical simulation methodology has been validated through reduced-scale wind tunnel experiments. A comparative analysis has been conducted on the characteristics of slipstream, wake flow, and upper flow between the original configuration (OC) and the braking configuration (BC) of the HSTs. The findings reveal that the application of braking plates promotes significant separation phenomena around the HSTs, enhancing the slipstream velocity distribution. In the BC, compared to the OC, the maximum value of the time-averaged slipstream velocity has increased by approximately 134.9% and 76.8% at the trackside and platform positions, respectively. Additionally, the TSI value of the slipstream velocity shows increases of around 100.4% and 210.4% at the trackside and platform positions, respectively. Meanwhile, the turbulence fluctuations within the wake region have been enhanced, with the formation of a longitudinal vortex alongside the railway subgrade, whose core nearly covers the TSI positions. Notably, obvious shifts occur within the upper flow field, which significantly strengthens both flow turbulence and slipstream velocity, potentially influencing components on the upper surface of HSTs, such as the pantograph. The deployment of braking plates contributes to a significant increase in overall vehicle pressure drag, thereby enhancing the train's aerodynamic drag. Relative to the OC, the aerodynamic drag of the HST has increased by approximately 235.4% in the BC.

Investigation on dynamic characteristics of droplet impact on surfaces with different rough microstructures based on lattice Boltzmann method

Constructing microstructures on smooth surfaces is significant for 3D printing technology and surface self-cleaning effects in engineering applications. This paper uses the lattice Boltzmann method (LBM) to study the droplet impact behavior on different microstructured surfaces: right-triangle, semicircular, and rectangular microstructures. The formulas for calculating the surface wetting characteristics of different microstructures are derived theoretically, the difference between simulation results and those from theoretical analyses is less than 5 %. The increase of the microstructure column height h may eventually lead to the disappearance of the Wenzel mode. The droplet impact on the microstructured hydrophilic surface can accelerate the droplet to the stable stage and reduce the excessive impact effect. The droplet impacts on the superhydrophobic microstructured surface can accelerate the rebound separation and shorten the time to reach the stable stage. When droplets impact the superhydrophobic surface of the right-triangle microstructure, a secondary separation phenomenon will occur, resulting in the maximum rebound height and the maximum reduction of the near-wall density. The superhydrophobic right-triangle microstructured surface can more effectively promote self-cleaning.

Distinct Element macro-crack networks for expedited discontinuum seismic analysis of large-scale URM structures

Discontinuum analysis is a powerful tool for the detailed seismic assessment of unreinforced masonry (URM) structures, whose widespread use is however still mostly limited to small-scale assemblies or isolated components. Despite their unique capabilities, including the explicit simulation of separation phenomena, collapses and out-of-plane (OOP) failures that are hardly replicable using traditional continuum solutions, the high computational cost entailed by micro-to-meso-scale discontinuum modelling strategies, which are the standard approaches in applied research, presently prevent their employment for building-scale problems. The few available macro-scale discontinuum models specifically conceived for URM, on the other hand, rely on complex geometrical discretization processes that require costly manual work, as well as on less efficient deformable block formulations. In this paper, a new simplified discontinuum macro-model is presented and validated against full-scale laboratory test outcomes on walls, pier-spandrel systems and building specimens, in addition to various meso-scale numerical results, under either in-plane (IP) or OOP actions, and considering quasi-static (monotonic, cyclic) or dynamic loadings. The proposed simulation technique, implemented in a robust Distinct Element Method (DEM) framework, leverages a semi-automated Equivalent Frame discretization algorithm that idealizes masonry piers, spandrels and nodes as an assembly of interlocked rigid macro-blocks connected by a network of zero-thickness interface springs. The latter are herein demonstrated to effectively replicate URM damage at the component-level through fracture energy contact laws, providing macro-scale yet representative failure patterns, as well as adequate predictions of overall strength and deformation capacities. Results obtained show a good agreement between macro- and more sophisticated meso-scale predictions, as well as with experimental outcomes, albeit dissimilarities among measured and computed force-displacement responses – similarly to other simplified strategies – were detected as vertical overburden increases. Notably, for analogous levels of accuracy, the analysis time required by our new macro-models is up to 150 times lower than its meso-counterparts. The use of the proposed simplified strategy also enabled the satisfactory simulation of the quasi-static cyclic and seismic responses of full-scale building-scale specimens, prohibitive tasks using traditional detailed DEM models, while also being up to 10 times faster than previous deformable macro-models.

Predicting p53-dependent cell transitions from thermodynamic models.

A cell's fate involves transitions among its various states, each defined by a distinct gene expression profile governed by the topology of gene regulatory networks, which are affected by 3D genome organization. Here, we develop thermodynamic models to determine the fate of a malignant cell as governed by the tumor suppressor p53 signaling network, taking into account long-range chromatin interactions in the mean-field approximation. The tumor suppressor p53 responds to stress by selectively triggering one of the potential transcription programs that influence many layers of cell signaling. These range from p53 phosphorylation to modulation of its DNA binding affinity, phase separation phenomena, and internal connectivity among cell fate genes. We use the minimum free energy of the system as a fundamental property of biological networks that influences the connection between the gene network topology and the state of the cell. We constructed models based on network topology and equilibrium thermodynamics. Our modeling shows that the binding of phosphorylated p53 to promoters of target genes can have properties of a first order phase transition. We apply our model to cancer cell lines ranging from breast cancer (MCF-7), colon cancer (HCT116), and leukemia (K562), with each one characterized by a specific network topology that determines the cell fate. Our results clarify the biological relevance of these mechanisms and suggest that they represent flexible network designs for switching between developmental decisions.

Optimization Design of Bionic Leading-edge Protuberances on Horizontal Axis Wind Turbine Blades

Abstract The complex operating environments of horizontal axis wind turbines has made the phenomenon of blade flow separation more obvious. As a passive flow control method, the bionic humpback whale leading-edge protuberances have been shown to effectively enhance the performance of the wind turbine. This study employs a multi-objective genetic algorithm and Computational Fluid Dynamics method to analyse the impact of leading-edge protuberances on the aerodynamic performance and flow characteristics of the blades. The results indicate a significant improvement in blade performance after optimization in the wind turbine’s output power. The streamwise vortices generated by the bionic protuberances not only reduce the suction surface pressure, but also suppress the spanwise flow over the blade surface. The length of the flow separation Region is reduced from 0.410 to 0.368 radius. In the process of wind speed change, the tangential forces on the bionic blade exhibit a wave-like variation. The bionic protuberance alters the pressure coefficient of the position. Compared with the original blade, the pressure coefficient of the trough sections on both sides of the bionic blade protuberance is improved. In this study, the bionic protuberance applied to the leading-edge of horizontal-axis wind turbine blades is proposed for the first time, and holds practical value for guiding practical applications.