Detachment Distance Research Articles

Leveraging liminality: how the interim manager’s liminal position facilitates knowledge transfer to client organizations

Purpose With the rise of the gig economy, management positions are increasingly staffed with flexible labor, so-called interim managers. They plunge into organizations for a limited period, operating in a liminal position as partly insider, partly outsider. Although several contributions to their client organizations are acknowledged, it is unknown how the interim manager’s knowledge from previous assignments is made useful in the new context under these particular working conditions. Therefore, the purpose of this paper is to increase the understanding of how the interim manager’s knowledge is transferred to the client organization while operating from a liminal position. Design/methodology/approach This paper presents an interview-based multiple case study of six interim assignments where knowledge transfer is considered a social and context-dependent process. Findings The findings unveil the multifaceted nature of the liminal position, which consists of task orientation, time limitation, political detachment and cultural distance. These facets contribute to knowledge transfer in terms of new shared understandings and joint interests, which in turn might create new practices that augment continuous knowledge-sharing patterns. Originality/value The results contribute to the research on flexible work arrangements by shedding light on how the liminal position, predominantly depicted as an obstacle for the individual, might facilitate knowledge transfer. Through the process of knowledge generation, it is shown how a short-term engagement might enable the organization to increase its knowledge over time.

Extended Pantograph–Catenary Arc Modeling and an Analysis of the Vehicular-Grounding Electromagnetic Transients of Electric Multiple Units

As the operating speed of electric multiple units (EMUs) in high-speed railways increases, pantograph–catenary (PC) detachment arcing occurs frequently. The resulting vehicular-grounding electromagnetic transients are related to the dynamic characteristics of the arc length. During large detachment, the processes of arc extinction and arc reignition may occur, resulting in more severe train body (TB) over-voltages and adverse effects on some vehicular electronic devices. As an extension of the previous works, this paper aims to establish a suitable PC arc model to examine the TB transient voltages. To begin with, the arc length dynamic characteristics are reasonably analyzed to deduce the relationship between the detachment distance and the arc length via the chain arc model. Then, the dynamic characteristics of the arc length are introduced, and an arc modeling scheme is proposed to elaborate the vehicle-grid electric power model for EMUs encountering various arcing scenarios. Based on this, the transient over-voltages are analyzed, accounting for both the arc extinction and arc reignition, as well as the mutual influences of multiple detachments in a short time. The influential factors, including arc length characteristics, phase angle, excitation inductance, and grounding parameters, are also involved in the performed analyses.

Investigation on the oil bridge between air bubble and glass surface in water: Formation, deformation, mechanical force and implications for froth flotation

In froth flotation, the insoluble oil as a liquid bridge between an air bubble and a solid surface in water is a common and important interface phenomenon. This paper investigated the impact of the oil bridge between an air bubble and a glass plane from aspects of mechanical forces acting on complex interfaces. An air bubble was pulling towards an oil droplet anchored on a flat glass slide under water compulsively. In this process, the high-speed camera was applied to observe the deformation of the interfaces and the mechanical forces were measured using a micro-force sensor. It was found that the air-water-oil (A-W-O) three-phase contact line (TPL) can form, expand and become stable rapidly within 85.0 ms when the bubble is attached to the oil droplet. The expansion of the A-W-O TPL provides an extra adhesion force to the air bubble. The oil formed an oil bridge connecting the bubble and the solid surface which shortened the attachment distance and extended the detachment distance. The mechanical force resulting from the oil bridge acting on the air bubble is equivalent to an air bubble directly adhering to a hydrophobically modified surface. The capillary force and pressure force were calculated and were found to be the major components of the mechanical force in the detaching process. This mechanical force was directly influenced by the interfacial tension vectors, the interface curvatures, and the TPL radius. The deformation on the interface, especially the A-W interface, is significant to the detachment process and related mechanical forces.

Clinical Outcomes of Descemet's Membrane Endothelial Keratoplasty without Routine Prophylactic Peripheral Iridotomy.

Institutional, tertiary care eye hospital. All patients who underwent DMEK or DMEK combined with phacoemulsification (DMEK triple) for Fuchs endothelial dystrophy, using a standardized protocol between August 2016 and July 2021, were included. Previous glaucoma surgery, laser PI, aphakia, or complicated pseudophakia were excluded. Primary outcomes: Incidence of pupillary block (PB). Graft detachment (GD), rebubbling rates, uncorrected (UCDVA) and best corrected logMAR distance visual acuity (BCDVA), and endothelial cell loss (ECL) at six months. Data were analyzed using the chi-square test and stepwise backward regression analysis. Results: 104 eyes of 72 patients were included. Four eyes (3.8%) developed PB; in two of these cases, standard protocol was not followed. Overall minor GD occurred in 43.2% (n = 45); significant GD was present only in 7 eyes (6.6%). Overall slit lamp rebubbling rate was 30% (n = 35), though only four patients were rebubbled in theatre (3.8%). PB, GD, and rebubbling rates did not vary with the surgeon, surgery, or tamponade (air or SF6 gas). UCDVA, BCDVA, and ECL at 6 months were 0.29 ± 0.31, 0.20 ± 0.28, and 40.46 ± 20.36%, respectively. Conclusions: Compared to previously reported outcomes of DMEK with PI, our results of PI less DMEK using a standardized protocol have a similar incidence of pupillary block, graft detachment, and rebubbling, with comparable visual acuity and endothelial cell loss.

Computational simulation of stent thrombosis induced by various degrees of stent malapposition.

Percutaneous coronary intervention with stent implantation is one of the most commonly used approaches to treat coronary artery stenosis. Stent malapposition (SM) can increase the incidence of stent thrombosis, but the quantitative association between SM distance and stent thrombosis is poorly clarified. The objective of this study is to determine the biomechanical reaction mechanisms underlying stent thrombosis induced by SM and to quantify the effect of different SM severity grades on thrombosis. The thrombus simulation was performed in a continuous model based on the diffusion-convection response of blood substance transport. Simulated models included well-apposed stents and malapposed stents with various severities where the detachment distances ranged from 0 to 400μm. The abnormal shear stress induced by SM was considered a critical contributor affecting stent thrombosis, which was dependent on changing SM distances in the simulation. The results illustrate that the proportion of thrombus volume was 1.88% at a SM distance of 75μm (mild), 3.46% at 150μm, and 3.93% at 400μm (severe), but that a slight drop (3.18%) appeared at the detachment distance of 225μm (intermediate). The results indicate that when the SM distance was less than 150μm, the thrombus rose notably as the gap distance increased, whereas the progression of thrombogenicity weakened when it exceeded 150μm. Therefore, more attention should be paid when SM is present at a gap distance of 150μm. Moreover, when the SM length of stents are the same, thrombus tends to accumulate downstream towards the distal end of the stent as the SM distance increases.

Computational analysis of experiments on shock detachment in hypersonic flow of nitrogen and carbon dioxide over a wedge

One of the most dramatic effects of vibrational and chemical non-equilibrium in hypersonic flows occurs in the bow-shock detachment process in flow over a wedge. This was shown theoretically and in reflected shock tunnel experiments by Hornung & Smith (J. Fluid Mech., vol. 93, 1979, pp. 225–239). In the present work, the effect is first demonstrated by computation of two-dimensional non-equilibrium flows. The effect of the finite transverse extent of the wedge is then studied by three-dimensional computations of non-relaxing flows. An analytical formula is obtained that gives the shock detachment distance of a finite wedge for ideal-gas and equilibrium flows. In the experiment, the finite transverse extent of the wedge competes with the non-equilibrium effects, as each introduces a new length scale. The carbon dioxide and nitrogen flows of the experiment are therefore computed in three dimensions and with two-temperature chemistry accounting for vibrational and chemical non-equilibrium. In the case of nitrogen flow, the agreement between experiment and computation is not good, the experimental detachment distance being larger. A number of possible reasons are quantitatively examined. A conclusive resolution of the discrepancy is considered to require a repeat of the experiment with more accurately characterized conditions. In the case of the carbon dioxide experiments, the computed results agree remarkably well with experiment. This is partially due to the fact that the condition is very close to equilibrium, where the sensitivity of the detachment process to relaxation effects is small. The analytical expression for the dimensionless detachment distance agrees very well with all the three-dimensional computations of non-relaxing flows.

Improved Metaheuristic-Driven Energy-Aware Cluster-Based Routing Scheme for IoT-Assisted Wireless Sensor Networks

The Internet of Things (IoT) is a network of numerous devices that are consistent with one another via the internet. Wireless sensor networks (WSN) play an integral part in the IoT, which helps to produce seamless data that highly influence the network’s lifetime. Despite the significant applications of the IoT, several challenging issues such as security, energy, load balancing, and storage exist. Energy efficiency is considered to be a vital part of the design of IoT-assisted WSN; this is accomplished by clustering and multi-hop routing techniques. In view of this, we introduce an improved metaheuristic-driven energy-aware cluster-based routing (IMD-EACBR) scheme for IoT-assisted WSN. The proposed IMD-EACBR model intends to achieve maximum energy utilization and lifetime in the network. In order to attain this, the IMD-EACBR model primarily designs an improved Archimedes optimization algorithm-based clustering (IAOAC) technique for cluster head (CH) election and cluster organization. In addition, the IAOAC algorithm computes a suitability purpose that connects multiple structures specifically for energy efficiency, detachment, node degree, and inter-cluster distance. Moreover, teaching–learning-based optimization (TLBO) algorithm-based multi-hop routing (TLBO-MHR) technique is applied for optimum selection of routes to destinations. Furthermore, the TLBO-MHR method originates a suitability purpose using energy and distance metrics. The performance of the IMD-EACBR model has been examined in several aspects. Simulation outcomes demonstrated enhancements of the IMD-EACBR model over recent state-of-the-art approaches. IMD-EACBR is a model that has been proposed for the transmission of emergency data, and the TLBO-MHR technique is one that is based on the requirements for hop count and distance. In the end, the proposed network is subjected to rigorous testing using NS-3.26’s full simulation capabilities. The results of the simulation reveal improvements in performance in terms of the proportion of dead nodes, the lifetime of the network, the amount of energy consumed, the packet delivery ratio (PDR), and the latency.

Elucidation of Adhesive Interaction between the Epoxy Molding Compound and Cu Lead Frames.

Clarification of adhesive interactions in semiconductor packages can improve reliability of power electronics. In this study, the adhesion interfaces between the epoxy molding compound and Cu-based lead frames were analyzed using the density functional theory. A resin fragment was prepared based on the polymer framework formed in the curing reaction of epoxy cresol novolac (ECN) and phenol novolac (PN), which are typical molding materials. The resin fragment was optimized on the surfaces of Cu and Cu2O. We calculated the charge density differences for adhesion structures and discussed the origin of adhesive interactions. The ECN–PN fragment’s adhesion to the Cu surface relied mainly on dispersion forces, whereas in the case of Cu2O, the resin bonded chemically to the surface via (1) σ-bonds formed between the ECN–PN’s OH group oxygen and coordinatively unsaturated copper (CuCUS) and (2) hydrogen bonds between resin’s OH groups and coordinatively unsaturated oxygen (OCUS) located close to to CuCUS, resulting in a stable adhesive structure. The energy required to detach the resin fragment from the optimized structure was determined using the nudged elastic band method in each model of the adhesive interface. Morse potential curve was used to approximate the obtained energy, and the energy differentiation by detachment distance yielded the theoretical adhesive force. The maximum adhesive stress was 1.6 and 2.2 GPa for the Cu and Cu2O surfaces, respectively. The extent to which the ECN–PN fragment bonded to the Cu2O surface stabilized was 0.5 eV higher than in the case of the Cu surface.

Evolution of heat transfer at the stagnation point during the detached bow shock establishment

The diffraction of a shock wave over a stationary body is a problem of interest associated with the starting of shock tubes and expansion tubes which are well suited to studies of hypersonic flows. However, these facilities are characterized by very short test times. The transient parameters during the establishment of the detached bow shock in such impulsive facilities are important for both data processing and experimental design. In the present study, numerical simulations are conducted to investigate the diffraction of a normal shock wave over a sphere and the subsequent transient phenomena in a viscous perfect-gas flow field. The incident shock Mach number ranges from 3 to 5 with a specific heat ratio of 1.4. Based on the theoretical description of the reflected shock position during bow shock formation, approximate solutions for the time histories of the stagnation-point heat flux are also derived. The analytical and numerical results agree well. The results show that the stagnation-point pressure and heat flux approach their steady-state values much more rapidly than the shock detachment distance does.

Spread characteristics of hydrogen vapor cloud for liquid hydrogen spill under different source conditions

During the storage and transportation processes of liquid hydrogen, the accidental spill could cause great damage. Mixture multiphase model and Realizable k-ε model are adopted to predict the spread of hydrogen cloud in liquid hydrogen spill. Effects of source parameters on spread characteristics of hydrogen cloud, including spill rate and liquid mass fraction, are analyzed. For the spill with various spill rates, the cases of fixed spill amount or spill time are considered in view of emergency response strategy to the spill source. The results show that the spreads of hydrogen vapor cloud in downwind and vertical directions can be both promoted by increasing the spill rate. When the total spill amount is fixed, the volume ratio of detonation cloud to flammable cloud at the spill termination instant increases firstly and then decreases with spill rate, due to the combined effects of near-source turbulence and mixing time with air. When the source is terminated after a fixed spill period, the detachment distances of flammable vapor cloud keep almost constant for the spill rates below 9.52 kg/s, while the cloud is more lifted if further increasing the spill rate, during which the role of the near-source turbulence overweighs that of the spill amount. The upward movement of flammable vapor cloud is promoted by increasing liquid mass fraction, with increased height and reduced detachment distance. The work provides a guidance to risk assessment and safe handling of liquid hydrogen.

Microbubble characteristic in a T-junction microchannel in microfluidic chip

ABSTRACTFormation characteristic of microbubble in a T-junction microchannel in polydimethylsiloxane (PDMS) microfluidic chip is investigated. Microbubble formation experiments are carried out to investigate the effects of liquid flow rate, gas pressure and gas channel width on the detachment volume and formation time of microbubble. The growth process of the bubble is described by the form of force analysis, and the definition of the bubble detachment distance is introduced. The equivalent spherical theoretical model of bubble detachment diameter prediction is established, and the numerical solution of the model is obtained by the fourth-order Runge–Kutta method. The prediction results of theoretical model correlate well with the experimental data.

Numerical investigation on the effects of dike around liquid hydrogen source on vapor cloud dispersion

Safety is one of the most important concerns in handling liquid hydrogen. Mixture model and Realizable k-ε model are adopted to simulate the spills of liquid hydrogen in the present work. Effects of a dike around the liquid hydrogen source on vapor cloud dispersion are numerically investigated. The dike increases the hydrogen concentration near the source, and promotes the upward movement of flammable cloud thanks to the enhanced mixing with air, reducing the cloud detachment distance. The time needed for the hydrogen vapor cloud to be diluted out of hazards is largely influenced by dike size, and introducing the dike does not necessarily increase the overall hazard duration. Increasing the height to length ratio of the dike makes the near-source region exposed to high hydrogen concentration for longer hazard duration, while detachment distance reduces with the increment in dike height.

Hypersonic flow past a spherically blunted nose cone: A computational study

The present study investigates the aerodynamic characteristics of spherically blunted nose cone at a hypersonic Mach number of 5.8, numerically. The studies are conducted for different combinations of bluntness ratios and semi-cone angles, at zero angle of attack, in order to ascertain the nose cone parameters which provide minimum aerodynamic drag coefficient. The velocity vector shows the flow deceleration near the nose, re-acceleration through the sides as well the formation of recirculation zones. The structure of bow shock formed ahead of the nose as well as shock detachment distance is depicted by the Mach number contours. It is observed that the shock detachment distance follows linearly increasing behaviour with increase in bluntness ratios for all semi-cone angles studied. An empirical expression is developed for the shock detachment distance using the regression analysis, which reveals that it is mainly a function of bluntness ratio. It is observed that the aerodynamics drag coefficient attains a minimum value for smaller, bluntness ratios and semi-angle. Further, the aerodynamic drag coefficient is observed to be a strong function of bluntness ratios for smaller semi-cone angles.

Extended Black-Box Model of Pantograph-Catenary Detachment Arc Considering Pantograph-Catenary Dynamics in Electrified Railway

With the increase of the train speed, the pantograph-catenary (PC) detachment becomes more frequent, which results in more serious PC detachment arc. In order to analyze the influence of PC detachment arc on the train system, several arc models are established. However, these models do not consider the actual PC detachment process. In this paper, an extended black-box model of PC arc is proposed, which considers the dynamic detachment process of PC based on the PC dynamics. First, the Habedank arc model is presented and the relationship of the PC detachment distance with the arc voltage and arc dissipated power is established. Next, the dynamic detachment trajectory is obtained from the dynamic simulation of the PC structure model. Then, by introducing the dynamic PC detachment trajectory model into the arc model, the dynamic arc model is built. Finally, the performance of the arc current and arc voltage is analyzed and the effectiveness of the dynamic arc model is verified.

A novel method for automatic retinal detachment detection and estimation using ocular ultrasound image

This paper presents a novel method for automated detection of retinal detachment from ocular ultrasound image using digital image processing and computational techniques. Retinal detachment (RD) is an ocular emergency in which retina gets detached from the tissues lying underneath it and often requires immediate intervention to prevent rapid, irreversible vision loss. Direct fundoscopy and visual field testing are most common methods for the detection of RD. These methods are difficult to perform and they do not completely rule out retinal detachment. Generally, Ophthalmologists use ocular ultrasound to enhance their clinical acumen in detecting RD. Sometimes it is difficult to extract diagnostic features from ultrasound (USG) images due to its poor quality. Also, noise present in the image would cause misinterpretation during visual inspection;this demands development of intelligent and automated techniques for detection of retinal detachment. Further, the paper proposes a novel frame work for accurate and automatic retinal detachment using image processing techniques and mathematical analysis of detached area contour detected within the ocular globe. Furthermore, the estimation of diagnostic parameters, indicative of retinal detachment is also computed. Based on the mathematical analysis, three such parameters, percentage area of detached retina (PADR) compared to the ocular globe, angular width of detachment (α) and maximum radial distance of detachment to choroid layer beneath it (β), are calculated. These estimated parameters are very useful in determining the exact location and extent of retinal detachment. Results obtained through the proposed retinal detachment detection scheme are validated by the radiologist.

Nanoscale compositional mapping of cells, tissues, and polymers with ringing mode of atomic force microscopy

Recently developed sub-resonance tapping modes (such as Digital Pulse, Peak Force Tapping, HybriD, etc.) of atomic force microscopy (AFM) allow imaging of compositional contrast of (bio)materials and biological cells down to the nanoscale. Here we report on a powerful extension of those modes, “ringing” mode, which more than doubles the number of non-trivial physical channels that can be collected with a regular sub-resonance tapping. It can simultaneously record five new additional compositional parameters related to adhesive and viscoelastic properties of the sample surface: the restored (averaged) adhesion, adhesion height, pull-off neck height, detachment distance, and detachment energy losses. Ringing mode can be up to 20 times faster and showing fewer artifacts compared to the existing sub-resonance tapping modes. Ringing mode is based on an analysis of ringing signal of the AFM cantilever after detaching the AFM probe from the sample surface (this signal is currently treated as noise, and typically filtered out in the existing modes). We demonstrate that this new mode allows recording robust and unique information on fixed human epithelial cells, corneocyte skin flakes, and polymers used for bioimplants.

Formation Characteristics of microbubble in a co-flowing liquid in microfluidic chip

Microbubble formation under the surroundings of co-flowing liquid (CFL) in a specially designed microfluidic chip was investigated. A new microfluidic chip utilizing several capillary tubes was fabricated to provide the co-axial flowing conditions. An experiment platform based on high-speed microscopic camera system (HSMCS) was designed and set up. The influences of nitrogen pressure and liquid flow rate on detachment distance and volume variation of target microbubble were studied experimentally. Experimental data and analysis results indicated that the detachment distance of target microbubble decreases substantially as the rate of CFL increases while it is almost independent of nitrogen pressure. Additionally, the volume growth rate of target microbubble almost keeps constant under fixed nitrogen pressure. The present study provides empirical references for studies in microbubble formation in microfluidic chips which contributes to realize the accurate controllability in diameter and size distribution of microbubble.

Numerical analysis on shock-cylinder interaction using immersed boundary method

The problem of shock interaction with a rigid circular cylinder has been investigated using a compressible immersed boundary method coupled with high-order weighted-essentially non-oscillatory (WENO) scheme. First, the accuracy of the developed code is validated. Then, influences of the incident shock Mach number on the flow-field structure and dynamic drag coefficient, as well as time evolution of the flow field are studied. For different shock Mach number, the flow structure shows very different features. At a given dimensionless time, both the normalized shock detachment distance and the normalized vertical distance from the highest point of the primary reflected shock to the centerline of the cylinder decreases with increasing shock Mach number. However, location of the upper triple point varies non-monotonically with shock Mach number. For a case with given shock Mach number, the trajectory of the upper triple point and the time evolution of the normalized vertical distance from the highest point of the primary reflected shock to the centerline of the cylinder can both be predicted by linear correlation. Nevertheless, the time evolution of the normalized shock detachment distance is biased to be non-linear. Meanwhile, time evolution of force exerted on the cylinder is quite unsteady for a case with given shock Mach number and given cylinder diameter. For small shock Mach number, there exists a negative valley, and it disappears when the incident shock Mach number increases to a large value, e.g., 1.7. Furthermore, correlations to predict the occurrence of the peak drag and its value under different shock Mach numbers have been proposed.

Microbubble Formation in a Co‐flowing Liquid in a Microfluidic Chip

AbstractMicrobubble formation from a capillary tube surrounded by a co‐flowing liquid (CFL) in a mechanically assembled microfluidic chip is investigated. The influences of gas pressure and liquid flow rate on the growth and detachment of the target microbubble are studied both experimentally and theoretically. A phenomenological theoretical model which consists of an expansion stage and a detachment stage is proposed based on a previous study to predict the detachment volume and formation time of microbubbles. The detachment distance is investigated experimentally in detail and later applied to the theoretical model. A MATLAB/Simulink simulation model is built for the solution of the proposed theoretical model. Model predictions correlate well with the experimental data in the present study.

Quantifying the effect of electric current on cell adhesion studied by single-cell force spectroscopy

This study presents the effect of external electric current on the cell adhesive and mechanical properties of the C2C12 mouse myoblast cell line. Changes in cell morphology, viability, cytoskeleton, and focal adhesion structure were studied by standard staining protocols, while single-cell force spectroscopy based on the fluidic force microscopy technology provided a rapid, serial quantification and detailed analysis of cell adhesion and its dynamics. The setup allowed measurements of adhesion forces up to the μN range, and total detachment distances over 40 μm. Force-distance curves have been fitted with a simple elastic model including a cell detachment protocol in order to estimate the Young's modulus of the cells, as well as to reveal changes in the dynamic properties as functions of the applied current dose. While the cell spreading area decreased monotonously with increasing current doses, small current doses resulted only in differences related to cell elasticity. Current doses above 11 As/m(2), however, initiated more drastic changes in cell morphology, viability, cellular structure, as well as in properties related to cell adhesion. The observed differences, eventually leading to cell death toward higher doses, might originate from both the decrease in pH and the generation of reactive oxygen species.