Detachment Mode Research Articles

Detached Plasma Studies in GOL-NB with Extra Gas Injection

The magnetic system of an open trap usually includes expansion sections located between highfield magnetic mirrors and end surfaces that receive plasma. In the GOL-NB device, an arc plasma gun is located in one of the expanders, which creates a low-temperature starting plasma in the confinement area. The parameters of the surface plasma sheath affect the electrical connection of the confinement area with the walls and, thereby, affect the contribution of the line-tying effect to the plasma stability and the longitudinal energy losses from the trap. The experiments with additional hydrogen injection into the plasma gun were carried out at GOL-NB. We observed a radiating plasma formation detached from the surface, which visually corresponds to that in radiating divertors in tokamaks. In both standard and detached modes, decaying plasma existed near the receiving electrodes during the entire observation time after the discharge current was terminated. In the central trap of GOL-NB, some structures in the Fourier spectrogram of magnetic fluctuations manifest earlier in the detachment mode than in the standard mode and have lower frequencies. We associate these structures with the onset of interchange-like modes due to the loss of plasma stabilization by the line-tying to the conducting ends. The observed plasma response to the additional gas supply confirmed our understanding of the line-tying effect as the main factor stabilizing the plasma core in the initial phase of density accumulation in the central trap.

Effect of turbulence intensity on bubble-particle detachment mechanism in a confined vortex

Bubble-particle detachment induced by turbulence is the primary factor for the low recovery of coarse particles, which has attracted much attention in recent years. The prevailing centrifugal detachment theory has achieved broad consensus. However, due to the complexity of bubble-particle aggregate motion in the turbulent field, the influence of turbulence intensity on bubble-particle detachment mechanism remains unclear. In this study, a controlled rotating vortex was generated using a custom-made fluid channel to systematically investigate the effect of turbulence intensity on bubble-particle centrifugal detachment. Firstly, detachment behaviours of bubble-particle aggregates were captured using high-speed cameras, followed by flow field visualization of bubble-particle detachment processes using Computational Fluid Dynamics (CFD). Experimental results reveal three typical detachment modes of bubble-particle aggregates in the confined vortex: fluid shear, bubble oscillation, and particle centrifugal motion, with particle centrifugal detachment becoming dominant with increasing turbulence intensity. This shift is attributed to changes in turbulence intensity directly affecting the trajectories of bubble/aggregates and indirectly influencing the detachment mode of bubble-particle. Compared to low turbulence intensity, bubble-particle aggregates exhibit smaller rotational radii under high turbulence intensity, reducing the probability of fluid shear and bubble oscillation detachment by mitigating the influence of high-speed shear zones at the top of the cavity. Conversely, particles located at the edge of aggregates are more susceptible to acceleration by sidewall flow fields, favouring detachment through particle centrifugal motion. Moreover, unlike traditional centrifugal detachment theories, particles do not merely undergo independent circumferential motion on the bubble surface but participate as a whole with bubbles in centrifugal motion governed by vortices. These findings are expected to provide fundamental insights into the bubble-particle detachment mechanism in turbulent fields.

Compatibility of divertor detachment and ELM suppression in DIII-D high- βp plasmas with ITER-similar shape

Integration of transient and steady-state divertor heat fluxes control with a high-performance core is necessary for future fusion reactors. In recent DIII-D high- βp experiments, divertor detachment and simultaneous edge localized mode (ELM) suppression are demonstrated while the plasma confinement quality is maintained high in ITER-similar shape. By optimizing the neon injection in high- βp scenario with ITER-similar shape, deep detachment and ELM suppression are achieved with a high-performance core ( βN ∼ 2.8, βp ∼ 2.3) at q95 ∼ 7.5. Partial divertor detachment and suppression of large ELMs are achieved at q95 ∼ 6. The stability analyses suggest that with low neon injection, the density pedestal becomes higher and steeper and the Ti profile also increases, therefore the increased edge pressure and higher current density destabilize the Peeling-Ballooning mode (PBM), which would lead to a large ELM collapse. With strong neon gas puffing, the significantly reduced pedestal pressure and current density, due to the degraded Te pedestal, lead to the stabilization of PBM and ELMs are suppressed. For both cases, the coupling between the large radius internal transport barrier (ITB) and edge pedestal is the key reason for maintaining high global performance. The formation of large radius ITB compensates for pedestal degradation. Such results could provide an attractive scenario to well control the transient and steady-state heat flux onto the divertor plates while maintaining good plasma performance, which is an important step toward the steady-state operation of future fusion reactors.

In Situ Observation and Electrical Signal Analysis of Different Bubble Detachment Modes on Microelectrode Surface

The deactivation of the reaction surface caused by bubble covering is an important factor that causes the decrease in the efficiency of water electrolysis. By combining an electrochemical workstation with a high-speed camera, the evolutionary properties of hydrogen bubble and potential were obtained on a horizontal microelectrode with a diameter of 100 μm. During the electrolysis, individual bubbles evolved periodically on the electrode surface. Under the influence of electrode adsorption, the detachment diameter of the bubble is independent of current density, but with the increase of current density, the bubble detachment frequency increases. With the increase of ethylene glycol (EG) concentration, the bubble detachment frequency increased. When the concentration of EG is greater than 7.5 g l−1, the surface tension of the solution is lower than that of water, at which time the detachment mode of the bubble changes. Separating the resistance caused by the bubbles from the total resistance, it was found that the additional resistance caused by the bubbles rapidly became smaller as the EG concentration increased until the EG concentration reached 7.5 g l−1. The total resistance decreases first and then increases when the EG concentration is greater than 3 g l−1.

Electrolyte design for the manipulation of gas bubble detachment during hydrogen evolution reaction

During electrochemical gas evolution reactions, the continuous and vigorous formation of gas bubbles hugely impacts the efficiency of the underlying electrochemical processes. In particular, enhancing the detachment of gas bubbles from the electrode surface has emerged as an effective strategy to improve reaction efficiency. In this study, we demonstrate that the detachment of H2 gas bubbles can be controlled by the electrolyte composition, which can be optimized. We employ a well-defined Pt microelectrode and utilize electrochemical oscillation analysis to elucidate the features of H2 gas bubble detachment. Our investigation explores how the behaviour of H2 gas bubbles responds to variations in electrolyte composition and concentration. The coalescence efficiency of electrochemically generated microbubbles, a critical factor determining the mode of H2 gas bubble detachment (random detachment vs. single H2 gas bubble detachment), is profoundly influenced by the electrolyte composition. Specifically, coalescence efficiency follows the Hofmeister series concerning anions and coalescence is consistently inhibited in the presence of alkali metal cations. Furthermore, we establish a comprehensive model that accounts for both thermal and solutal Marangoni effects, allowing us to rationalize the trend of detachment size and period of single H2 gas bubbles under various conditions.

How Hydrothermal Cooling and Magmatic Sill Intrusions Control Flip‐Flop Faulting at Ultraslow‐Spreading Mid‐Ocean Ridges

Abstract“Flip‐flop” detachment mode represents an endmember type of lithosphere‐scale faulting observed at almost amagmatic sections of ultraslow‐spreading mid‐ocean ridges. Recent numerical experiments using an imposed steady temperature structure show that an axial temperature maximum is essential to trigger flip‐flop faults by focusing flexural strain in the footwall of the active fault. However, ridge segments without significant melt budget are more likely to be in a transient thermal state controlled, at least partly, by the faulting dynamics themselves. Therefore, we investigate which processes control the thermal structure of the lithosphere and how feedbacks with the deformation mechanisms can explain observed faulting patterns. We present results of 2‐D thermo‐mechanical numerical modeling including serpentinization reactions and dynamic grain size evolution. The model features a novel form of parametrized hydrothermal cooling along fault zones as well as the thermal and rheological effects of periodic sill intrusions. We find that the interplay of hydrothermal fault zone cooling and periodic sill intrusions in the footwall facilitates the flip‐flop detachment mode. Hydrothermal cooling of the fault zone pushes the temperature maximum into the footwall, while intrusions near the temperature maximum further weaken the rock and promote the formation of new faults with opposite polarity. Our model allows us to put constraints on the magnitude of two processes, and we obtain most reasonable melt budgets and hydrothermal heat fluxes if both are considered. Furthermore, we frequently observe two other faulting modes in our experiments complementing flip‐flop faulting to yield a potentially more robust alternative interpretation for existing observations.

Effect of Asymmetry on the Contact Time of Droplet Impact on Superhydrophobic Cylindrical Surfaces.

Reducing the contact time during the droplet impact on the surface is crucial for anti-icing, self-cleaning, and heat transfer optimization applications. This study aims to minimize the contact time by modifying the surface curvature to create an asymmetric impact process. Our experiments showed that the increase in Weber numbers (We) and the decrease in the ratio of surface diameter to droplet diameter (D*) intensify the asymmetry of the impact process, yielding four distinct rebound modes. Low asymmetry observes the liquid retract toward the central point (Rebound Modes 1 and 2), whereas high asymmetry yields a wing-like rebound (Rebound Modes 3 and 4). In Rebound Mode 1, increased asymmetry would lead to more extended contact due to the prolonged waiting period. Conversely, the reduction in contact time in Rebound Mode 2 occurs due to increased asymmetry with no waiting period. For Rebound Modes 3 and 4, the retraction time could be divided into three stages, generated by two liquid detachment modes from the surface. Analysis reveals that an increased asymmetry would reduce the retraction time during the first stage but prolong it during the third stage, with no significant effects on the second. Four correlations, each pertaining to a distinct impact mode, are proposed based on these analyses to describe the contact time concerning We and D* for droplets impacting a superhydrophobic cylindrical surface.

Detachment, hesitation, indifference: An anthropology of the religious being

In this article, the author attempts to retrace his various explorations of religious experience: rituals in Belgium, Catholic parishes in France, and his own experiences of belief. A common theme emerges: a negation that is found in the modes of human presence and that has various expressions. During rituals, it primarily concerns modes of detachment and distraction; during parish meetings, it involves modes of oscillation to deal with the obscurity of religious statements. It also includes a sort of reserve or hesitation, which the author has observed in his own belief. The article hypothesizes that these modes of hesitation originate from the very first act of believing, which may date back 100,000 years. Specifically, the author identifies that moment as the starting point of a mode of human presence that is characterized by presence-absence and indifference. A section of this article consists of a critical debate between the author’s own concepts and the ontological turn in anthropology.

The porous structure induced heterogeneous and localized failure of the biofilm in microfluidic channels.

Understanding the mechanism of biofilm distribution and detachment is very important to effectively improve water treatment and prevent blockage in porous media. The existing research is more related to the local biofilm evolving around one or few microposts and the lack of the integral biofilm evolution in a micropost array for a longer growth period. This study combines microfluidic experiments and mathematical simulations to study the distribution and detachment of biofilm in porous media. Microfluidic chips with an array of microposts with different sizes are designed to simulate the physical pore structure of soil. The research shows that the initial formation and distribution of biofilm are influenced by bacterial transport velocity gradients within the pore space. Bacteria prefer to aggregate areas with smaller microposts, leading to the development of biofilm in those regions. Consequently, impermeable blockage structures form in this area. By analyzing experimental images of biofilm structures at the later stages, as well as coupling fluid flow and porous medium, and the finite element simulation, we find that the biofilm detachment is correlated with the morphology and permeability (kb) (from 10-15 to 10-9 m2) of the biofilm. The simulations show that there are two modes of biofilm detachment, such as internal detachment and external erosion.

Nonlinear CZM-based predictive analysis of damage in single-lap composite joints: An exploration of the FGM concept in Fiber–Matrix coupling

This study introduces an innovative numerical approach, validated through experiments, to incorporate functional graded materials (FGMs) volume fractions into mixing laws for fiber–matrix unidirectional composites. Nonlinear techniques address adhesive ductility, with the cohesive zone modelling (CZM) model integrated into finite element analysis using the ABAQUS code. The CZM model encompasses shear and detachment modes, characterized by adhesive stress increase in a trapezoidal shape. Proposed strategies introduce layer-specific fiber presence; concepts like C-1 exhibit denser fibers toward the middle, while C-2 and C-3 position them nearer to the plate edge. Stiffness from attached plates significantly governs overall responses, particularly under mixed loading conditions. The results have shown that the proposed grading concept C-2 provides an over-resistance capacity compared to other concepts. Additionally, using a special mesh in the composite grading, the results indicate that the adhesive formulation used in this analysis and the approach followed are primarily based on experimental results, demonstrating good agreement with the numerical model employed.

Le détachement paradoxal en la Présence de l’Infini

The Presence of the Infinite in human existence may be considered as mystery. If so, then believers endorse three a priori. Firstly, human person, as finite, has the intuition of the Infinite that opens the way to an existential positioning in front of the Infinite. Secondly, the intuition of the Infinite gives birth to an idea of the Infinite, and eventually to the desire of the Infinite (the desire to be United with such Infinite). Thirdly, the idea of the Infinite allows believers to develop a fragmentary understanding of the ultimate ground for being and existence. The Infinite is thus unknowable by human (finite) beings. Being in the Presence of the Infinite then becomes a paradox that requires detachment. Being detached is being absolutely centered on God rather than any other existential concern. It requires two basic modes of detachment : the detachment from language and conceptual knowledge, on one hand, and the detachment of the self in relation with the Infinite, on the other hand. Being attached is considering God as a being who is alongside innumerable beings. Detachment rather allows believers to avoid the interpretative trap of the objectification of God.

Experimental verification of the additivity between the barrel droplet's drag force and the fiber number

AbstractResearch on the single fiber scale has an essential application value in the coalescence field. The study of the droplets' behavior on the fiber junctions can provide support data for optimizing the coalescer's drainage performance on the macroscopic scale. However, relevant research focusing on the force change of droplets during the transition from a single fiber to multifiber is relatively scarce. The droplet migration platform was built using the Lavision particle image velocimetry system, which can observe the behavior of droplets on fibers. The force and fiber number relationship were analyzed when the droplets were separated from the fiber junctions. Two detachment modes were observed during separation. Furthermore, the drag force satisfied the additivity theorem by increasing the number of fibers under the same detachment mode. In addition, the minimum Reynolds number prediction model was established under two separation forms, which had good prediction compared to the experimental data.

Mechanisms of detachment in fibrillar adhesive systems

Several creatures can climb on smooth surfaces with the help of hairy adhesive pads on their legs. A rapid change from strong attachment to effortless detachment of the leg is enabled by the asymmetric geometry of the tarsal hairs. In this study, we propose mechanisms by which the hairy pad can be easily detached, even when the hairs possess no asymmetry. Here, we examine the possible function of the tibia-tarsus leg joint and the claws. Based on a spring-based model, we consider three modes of detachment: vertically pulling the pad while maintaining either a (1) fixed or a (2) free joint, or by (3) flexing the pad about the claw. We show that in all cases, the adhesion force can be significantly reduced due to elastic forces when the hairs deform non-uniformly across the array. Our proposed model illustrates the design advantage of such fibrillar adhesive systems, that not only provide strong adhesion, but also allow easy detachment, making them suitable as organs for fast locomotion and reliable hold. The presented approaches can be potentially used to switch the adhesion state in bio-inspired fibrillar adhesives, by incorporating artificial joints and claws into their design, without the need of asymmetric or stimuli-responsive fibrillar structures.

Mushroom-Shaped Micropillar With a Maximum Pull-Off Force

Abstract The bioinspired structure of the mushroom-shaped micropillar has been considered a blueprint of functionalized adhesives due to its prominent dry adhesive performance. Among the design strategies, the geometrical parameters of the stalk and tip are of significance for improving their adhesion performance. In this study, mushroom-shaped micropillars in different diameters of the stalk and tip are fabricated by a new fabrication approach, and the adhesion measurements are performed to study the influences of loading conditions and geometrical parameters on the pull-off force. The experimental and numerical results suggest that the stalk and tip diameters strongly affect the interfacial detachment behavior and the pull-off force. Two detachment modes are distinguished by the positions of the crack initiation. Finite elemental analyses reveal the detachment mechanisms by the interfacial stress distribution and damage evolution. According to the detachment mechanisms, a structure design strategy for mushroom-shaped micropillar with maximum pull-off force is proposed. The present studies provide a fresh insight into the adhesion behaviors of mushroom-shaped micropillars and contribute to the future adhesive design.

A comparison of modal analyses of foil-air bearing rotor systems using two alternative linearisation methods

When applied to the free vibration (modal) analysis of foil-air bearing rotor systems, the classical linear force coefficients method (LFCM) can be regarded as an indirect form of linearisation that eliminates the air film and foil state variables. Research into its accuracy has been limited to its predictive ability for the instability onset speed compared against the low amplitude response of the nonlinear system. Two recent studies highlighted issues that artificially inflated the method discrepancies reported previously. This paper verifies the LFCM on a series of cases and identifies indisputable ones where it gives misleading results. A novel robust procedure is devised for the LFCM computation of Campbell diagrams and modal stability plots. A first-ever study of the accuracy of the LFCM’s modal analysis capability is carried out using as benchmark the recently developed direct linearisation method. In contradiction to a recent study, the LFCM results did not exhibit a systematic error as the foil compliance increases, though it is not excluded that such an error may occur in other situations. The two cases identified where the LFCM gave misleading predictions relate to pad flutter with top foil detachment and half engine order whirl modes attributed to the air film.

Ice adhesion of PDMS surfaces with balanced elastic and water-repellent properties

HypothesisIce adhesion to rigid materials is reduced with low energy surfaces of high receding contact angles. However, their adhesion strength values are above the threshold value to be considered as icephobic materials. Surface deformability is a promising route to further reduce ice adhesion. ExperimentsIn this work, we prepared elastomer surfaces with a wide range of elastic moduli and hydrophobicity degree and we measured their ice adhesion strength. Moreover, we also explored the deicing performance of oil-infused elastomeric surfaces. The ice adhesion was characterized by two detachment modes: tensile and shear. FindingsThe variety of elastomeric surfaces allowed us to simultaneously analyze the ice adhesion dependence with deformability and contact angle hysteresis. We found that the impact of these properties depends on the detachment mode, being deformability more important in shear mode and hydrophobicity more relevant in tensile mode. In addition, oil infusion further reduces ice adhesion due to the interfacial slippage. From an optimal balance between deformability and hydrophobicity, we were able to identify surfaces with super-low ice adhesion.

Stick–slip phenomena and Schallamach waves captured using reversible cohesive elements

Reversibility is of paramount importance in the correct representation of surface peeling in various physical settings, ranging from motility in nature, to gripping devices in robotic applications, and even to sliding of tectonic plates. Modeling the detachment–reattachment sequence, known as stick–slip, imposes several challenges in a continuum framework. Here we exploit customized reversible cohesive elements in a hybrid finite element model that can handle occurrence of snap-through instabilities. The simulations capture various peeling phenomena that emerge in experimental observations, where layers are pulled from a flat, rigid substrate in the direction parallel to the surface. For long layers, periodicity in reattachment is shown to develop and is linked to the concept of Schallamach waves. Further, the connection between surface properties and stick–slip behavior is investigated: we find that stick–slip is linked to the propensity of the interface to localize deformation and damage. Beyond elucidating the various peeling behaviors and the detachment modes, the computational framework developed here provides a straightforward approach for investigation of complex delamination processes, which can guide the development of future applications across different scales and in various settings.

Theistic and Non-Theistic Modes of Detachment from the Presence of the Infinite

In this article, we will describe two theistic modes of “paradoxical detachment” from the Presence of the Infinite, implying the coexistence of attachment and detachment. We will analyze two forms of Christianity-based paradoxical detachment: (a) being dependent on the Ground of soul, while being detached from the representations of the Infinite (Master Eckhart); (b) being absolutely dependent on the Infinite, while being detached from any religious morality (Friedrich Schleiermacher). The nontheistic mode of detachment from the Presence of the Infinite requires an absolute detachment. We will examine two forms of absolute detachment towards the Presence of the Infinite: on one hand, the all-encompassing emptiness in the Kagyü and Gelug lineages of Tibetan Buddhism; on the other hand, the Heideggerian notion of “groundless abyss.” In the Kagyü and Gelug lineages of Tibetan Buddhism, being absolutely detached is searching for the Enlightenment, while being detached from all concepts. Heideggerian notions of “groundless abyss” and “de-hominization” allow us to reach absolute detachment, while remaining in a non-theistic way of thinking.

Vegan attendance: reading Gibbons’s animals

When we encounter the work of Grinling Gibbons, we find ourselves in the presence of multiple non-human animals. However, it is unclear how one should address these presences. On the one hand, for ecofeminist scholars such as Josephine Donovan, the aestheticization of animal death is to be vehemently resisted and the embodied presence of animals recovered by looking beyond the surface: a mode of looking that Donovan terms ‘attentive love’. On the other hand, a re-reading of the philosophical ideas of Simone Weil, upon which Donovan premises her argument, suggests that attention to others requires a mode of radical detachment. These two positions speak in important ways to the dilemmas faced by a vegan spectator. Drawing on Jason Edwards’s previous work on ‘the vegan viewer’, this article seeks to reconcile a vegan resistance to Gibbons’s depictions of animal death, in their spontaneous falling under human dominion, with the aesthetic pleasure generated by Gibbons’s craftmanship. I therefore propose ‘vegan camp’ as a means of reconciling oneself to insufficiency and complicity in systems of violence without renouncing pleasure. Vegan camp is detailed as an aesthetics that acknowledges the violence of humanity and one’s inescapable place within it, dissolving the subjective idea of the beautiful vegan soul to pay attention to the pervasive presence of an anthropocentrism that, in the case of Gibbons, decoratively adorns the sites at which animals might be eaten, worn, or offered up for sacrifice.

Disruption of biofilm formation by fractions from book gills and carapace of horseshoe crab Tachypleus gigas

ABSTRACT Horseshoe crabs have survived for a long period due to their myriad defence mechanism. Thorough studies were conducted on their adaptive defence mechanisms but few highlighted their primary innate defence. This study aimed to determine the antifouling properties of the methanolic crude extracts and fractions obtained from the book gills and carapace of the Tachypleus gigas and to characterize their bioactive metabolites, using the detachment and preventive measurements. The active fractions recovered from the recycling HPLC were further analysed using GC-MS and major active constituents were identified. The results obtained indicated that the extract and fractions of T. gigas had significant detachment mode of actions for antifouling activities. Chemical interactions such as synergistic effects were observed in both the book gills and the carapace. Chemical profiles indicated the presence of organic acids such as amino acid, simple sugars and fatty acids. The observed activities might be caused by nutrient-induced biofilm dispersion mechanisms. These findings may provide new insight into the defence mechanism of the horseshoe crabs against biofilm formation. The isolated active fractions and the identified molecules from the horseshoe crab T. gigas may be applied as a dispersal antifouling agents. Further studies are needed to confirm these prospective potential applications.