bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chronic pain: a long‐term sequela of epidermal necrolysis (Stevens–Johnson syndrome/toxic epidermal necrolysis) – prevalence, clinical characteristics and risk factors
Authors: Lefaucheur J.‐P. , Valeyrie‐Allanore L. , Ng Wing Tin S. , Abgrall G. , Colin A. , Hajj C. , de Prost N. , Wolkenstein P. , Ingen‐Housz‐Oro S. , Chosidow O. 
Published: August 2020

AbstractBackgroundStevens–Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are associated with various sequelae. Chronic pain, one of these sequelae, has never been systematically evaluated.Objectives and methodsTo assess the persistence of pain in a single‐centre cohort of 113 consecutive patients with SJS/TEN. From this cohort, 81 patients were interviewed more than 1 year after the initial episode and included in the study. Data were collected according to standardized questionnaires.ResultsFrom the 81 interviewed patients, 52 patients (64%) were painless and 29 patients (36%) were painful. Chronic pain syndrome was associated with a more severe initial acute phase of the disease (larger extent of detachment, higher SCORTEN, increased rate of admission in ICU and complications, and longer hospital stay). Pain was mainly located at the level of eyes (55%), mouth and lower limbs (38–41%), with a moderate daily intensity on average (4.7/10). The ‘affective’ descriptors prevailed over the ‘sensory’ descriptors, with the exception of burning and itching sensations. Finally, regarding provoked pain, mechanical allodynia (to brushing and pressure) was more marked than thermal allodynia.DiscussionThe persistence of chronic pain after SJS/TEN is a common phenomenon. Sensory descriptors are consistent with sensitization of both small‐diameter nerve fibres (burning and itching sensations) and large‐diameter nerve fibres (mechanical allodynia), but the affective‐emotional components of pain largely predominate.ConclusionsComplex mechanisms lead to persistent pain as long‐term sequela of SJS/TEN, among which mechanisms, psychological factors related to post‐traumatic stress disorder probably play a key role.
Challenges in Validating a Thermo-Hydrodynamic Gas Foil Bearing Model
Authors: Michel Hanns , Liebich Robert 
Published: August 2020

Abstract
Gas foil bearings (GFBs) are suitable for high speed and temperature applications where conventional lubricated bearing solution are not feasible. This requires the prediction of bearing temperatures and thus a thermal model considering the heat generation and heat flow paths in the bearing. The effects of two different bump foil stiffness (Iordanoff, I., 1999, “Analysis of an Aerodynamic Compliant Foil Thrust Bearing: Method for a Rapid Design,” ASME J. Tribol., 121(4), pp. 816–822; Le Lez, S., Arghir, M., and Frene, J., 2007, “A New Bump-Type Foil Bearing Structure Analytical Model,” ASME J. Eng. Gas Turbines Power, 129(4), pp. 1047–1057.) and heat transfer models (a simplified and a detailed one) are presented in respect to measured temperatures from literature (Radil, K., and Zeszotek, M., 2004, “An Experimental Investigation Into the Temperature Profile of a Compliant Foil Air Bearing,” Tribol. Trans., 47(4), pp. 470–479; Sim, K., and Kim, T. H., 2012, “Thermohydrodynamic Analysis of Bump-Type Gas Foil Bearings Using Bump Thermal Contact and Inlet Flow Mixing Models,” Tribol. Int., 48, pp. 137–148). The comparison is drawn over a wide range of operational conditions as well as measuring positions, which in such detail has not been shown before. While good agreement is found for some of the conditions and positions, only reasonable agreement is found for others. The deviations and difficulties in validating a thermal model against experiments are highlighted in a discussion about various temperature influencing parameters, especially concerning the change of clearance during operation. In conclusion, it is found that the models are able to predict temperatures reasonably well, but require delicate fine-tuning to achieve these results. Finally, the impact of temperature distribution on the maximum load capacity is evaluated by comparing predictions between an isothermal model and one including thermal effects.
Structured to Succeed? Strategy Dynamics in Engineering Systems Design and Their Effect on Collective Performance
Authors: Valencia-Romero Ambrosio , Grogan Paul T. 
Published: August 2020

Abstract
Strategy dynamics are hypothesized to be a structural factor of interactive multi-actor design problems that influence collective performance and behaviors of design actors. Using a bi-level model of collective decision processes based on design optimization and strategy selection, we formulate a series of two-actor parameter design tasks that exhibit four strategy dynamics (harmony, coexistence, bistability, and defection) associated with low and high levels of structural fear and greed. In these tasks, design actor pairs work collectively to maximize their individual values while managing the trade-offs between aligning with or deviating from a mutually beneficial collective strategy. Results from a human subject design experiment indicate cognizant actors generally follow normative predictions for some strategy dynamics (harmony and coexistence) but not strictly for others (bistability and defection). Cumulative link model regression analysis shows that a greed factor contributing to strategy dynamics has a stronger effect on collective efficiency and equality of individual outcomes compared to a fear factor. Results of this study provide an initial description of strategy dynamics in engineering design and help to frame future work to mitigate potential unfavorable effects of their underlying strategy dynamics through social constructs or mechanism design.
Optimizing Architecture Transitions Using Decision Networks
Authors: Siddiqi Afreen , Rebentisch Eric , Dorchuck Samuel , Imanishi Yuto , Tanimichi Taisetsu 
Published: August 2020

Abstract
Architecture selection for systems undergoing rapid technological and market change is challenging. It is desirable to select architectures that can provide cost-effective possibilities for future changes and avoid architecture lock-in. However, optimal architectures for prevailing conditions may not be changeable for future adaptation. This tension between objectives for system (product) development for both short-term and long-term competitiveness has been an enduring challenge for system architects. Here, we use time-expanded decision networks (TDNs) with time-varying costs and demands to systematically explore future architecture transition pathways and strategically identify useful designs. We demonstrate a new application for autonomous driving (AD) systems, a nascent technology, where the design and capabilities of constituent components (such as sensors, processors, and data communication links) are still evolving and significant market and regulatory uncertainties persist. In this case, we model technology costs with time-based factors to explicitly include future trends. The results show that as cost differences between architectures increase and demand for new functionality changes with time, the approach is able to identify potential transition points between architecture choices that optimize the net present value (NPV) of the system. For some of the specific scenarios analyzed in this study, the NPV with optimal architecture transitions is at least 10–20% larger as compared with fixed cases. Overall, this work presents a case for planning and partly constructing architecture transition roadmaps for new systems wherein dominant architectures have not emerged.
An Assessment of the Drag Models in the Case of a Shock Interacting With a Fixed Bed of Point Particles
Authors: Koneru Rahul Babu , Balachandar S. 
Published: August 2020

Abstract
In this work, three-dimensional Euler–Lagrange (EL) point-particle simulations of a shock wave interacting with a fixed bed of particles are carried out. The results from the particle-resolved (PR) simulations are used to assess the performance of the point-particle drag models during short time scales. We demonstrate that in a one-way coupled regime, the point-particle simulations recover the dominant gas dynamic features of the flow and are in a good agreement with the exact Riemann solution of a shock traveling through a sudden area contraction. Although the PR simulations are inviscid, we show that a dissipative drag is necessary to predict the mean behavior of the gas. As a model for the inviscid shock-induced (SI) drag two different models are presented in lieu of the quasi-steady drag. Finally, two-way coupled simulations are performed at four different particle volume fractions {0.10, 0.15, 0.20, 0.25} and three different incident shock Mach numbers {1.22, 1.66, 3.0} and compared against the data from PR inviscid simulations. At a lower Mach number (1.22), averaged flow quantities from the two-way coupled simulations agree well with the PR simulations. As the Mach number increases, we observe that the discrepancies between the point-particle and the PR simulations grow. A sensitivity analysis of the drag models involved reveals a strong influence of the inviscid-unsteady force on the gas quantities especially in the case of a strong shock interacting with a dense bed of particles. The use of Mach correlation beyond the subcritical regime coupled with the model for volume fraction correction is identified as a probable cause for the additional drag.
Numerical and Theoretical Study on the Varying Speed Impact of Wedge Bodies on a Water Surface
Authors: Wen Xueliang , Liu Peiqing , Qu Qiulin , Hu Tianxiang 
Published: August 2020

Abstract
The varying speed impact of wedge bodies on a water surface is studied numerically and theoretically to provide a fast and accurate prediction of the pressure on the wedge surface and the motion of wedge bodies during the free impact, which can be a two-dimensional (2D) model for the strip theory or 2D + t strategy. The fluid is assumed to be incompressible, inviscid, with negligible gravity effect and surface tension effect. The computational fluid dynamics (CFD) method is based on the volume of fluid (VOF) method and global moving mesh (GMM) method. Various cases of a varying speed impact are shown for the CFD method, and a linear relationship between the pressure coefficient Cp and a dimensionless variable K is observed. To clearly explain the linear relationship between Cp and K, we follow the potential theory to derive the Cp expression based on several assumptions on the free surface drawn from the CFD results. The Cp expression and the motion of wedge bodies for a free impact derived from it are considered as an approximate solution for a varying speed impact. The approximate solution is compared with the existing analytical models and the published experimental data. The approximate solution can work well for different deadrise angles, while the existing analytical models can only be used for small deadrise angles. Good agreement is also obtained between the approximate solution and the experimental test results, including the time history of wedge acceleration and the pressure on the wedge surface.
Transition and Turbulence Modeling for the Prediction of Cavitating Tip Vortices
Authors: Liebrand Rens , Klapwijk Maarten , Lloyd Thomas , Vaz Guilherme 
Published: August 2020

Abstract
This study evaluates the influence of transition and turbulence modeling on the prediction of wetted and cavitating tip vortices for an elliptical wing, while investigating the numerical errors. Transition modeling increases the quality of numerical predictions since the assumption of a fully turbulent boundary layer, commonly found in literature, contributes to underprediction of the tip vortex cavity size. By applying the local correlation-based transition model (LCTM) and controlling the boundary layer thickness using different turbulent inflow conditions, the pressure in the vortex was found to reduce by 20% for an Angle of Attack (AoA) of 5 deg. The consequent increase in cavity size was found to be of a similar order of magnitude. At 9 deg AoA, transition always occurs just downstream of the leading edge, making this AoA more suitable to investigate the effect of different turbulence modeling approaches. Azimuthal and axial velocity fields are validated against stereographic-particle image velocimetry (S-PIV) measurements. The time-averaged velocity profiles predicted by delayed detached-eddy simulation (DDES) and improved delayed detached-eddy simulation (IDDES) are close to the experiments; however, no velocity fluctuations and vortex dynamics are observed around the vortex. A comparison of wetted and cavitating simulations shows that the cavity leads to a change in the balance between production and destruction of turbulence kinetic energy, which reduces the turbulent diffusion in and around the cavity compared to wetted flow conditions. Consequently, the vapor flow exhibits the characteristics of a potential flow. Whether this is physically plausible remains to be investigated.
Numerical Framework and Design Optimization of an Intrinsically Compliant 3-DOF Parallel Robot
Authors: Hussain Shahid , Jamwal Prashant K. , Kapsalyamov Akim , Ghayesh Mergen H. 
Published: August 2020

Abstract
Parallel robots are multiple degrees of freedom (DOFs) systems that are typically used in applications characterized by enhanced accuracy, rigidity, and large force requirements within a compact workspace. In the present research, an intrinsically compliant parallel robot with 3-DOFs, actuated using four pneumatic muscle actuators (PMA), is conceptualized, developed, and analyzed. Despite many benefits, parallel robots also offer certain challenges that arise from the highly coupled and nonlinear motion of their actuators. The small workspace of parallel robots has many singularities and solving a closed-form forward kinematics (FK) for its end-effector motion is complicated. The PMAs can provide intrinsically compliant robotic motions, however, since they are flexible, their unilateral actuation also poses constraints on the achievable DOFs. The present research focuses on analyzing kinematics and dynamics of the developed parallel robot incorporating the stiffness together with force closure analyses besides suggesting design improvements as a consequence of the singularity analysis. Design synthesis and multi-criteria optimization have been performed to obtain a robot design which may provide higher accuracies (near unity condition number), quick response to external wrench (stiffness and rigidity), and reduced actuator force requirements. SPEA2 (Improved Strength Pareto Evolutionary Algorithm) has been implemented to carry out the simultaneous optimization of design objectives and provide Pareto optimal design solutions.
Comparative Assessment of Liquid Sodium and Gallium as Emergency Coolants in Nuclear Energy Applications
Authors: Zamora Blas 
Published: August 2020

Abstract
The influence of the thermophysical variable properties on the buoyancy-driven flows of liquid sodium and gallium established in a cylindrical cavity is numerically investigated, for the entire range of Rayleigh number corresponding to practical applications. Axisymmetric turbulent simulations (initially steady) are obtained, considering appropriate boundary and reference conditions for simulating the emergency cooling of a nuclear reactor. The results obtained for different heating intensities are analyzed and compared. In the case of sodium, the expected decay in the heat transfer coefficients is less relevant than that previously obtained for airflows. In turn, strong differences in the gallium thermal behavior are encountered. In fact, a trend opposite to that of sodium is detected for wide ranges of Rayleigh number and heating parameter. Additional transient simulations are carried out to complete a comparative assessment of the performance of both liquid sodium and gallium as cooling agents.
Experimental Study on the Effect of Localized Blockages on the Friction Factor of a 61-Pin Wire-Wrapped Bundle
Authors: Childs Mason , Muyshondt Robert , Vaghetto Rodolfo , Nguyen Duy Thien , Hassan Yassin 
Published: August 2020

Abstract
The thermal-hydraulic behavior of the flow in rod bundles has motivated numerous experimental and computational investigations. Previous studies have identified potential for accumulation of debris within the small subchannels of typical wire-wrapped assemblies with subsequent total or partial blockage of subchannel coolant flow. A test campaign was conducted to study the effects of localized blockages on the bundle averaged friction factor of a tightly packed wire-wrapped rod bundle. Blockages were installed within the bundle, and fluid pressure drop was measured across one wire pitch for a Reynolds number range of 500–17,200. The Darcy–Weisbach friction factor of the perturbed rod bundle geometry was compared with that of the unblocked bundle, as well as with the predictions of a well-established friction factor correlation. Differing effects based on blockage size and location for various flow regimes were studied. A number of conclusions can be made about the effects of the blockages on the friction factor, such as an increasing effect of the blockage on friction factor with an increase in Reynolds number, a change in flow behavior in the turbulent transition flow regime near Reynolds number 3000, differences in effect on friction factor for different types of subchannel blockage, and a nonlinear trend in friction factor variation with flow area impeded for edge subchannels. To this end, all data and quantified uncertainty produced in this study are made available for comparison and validation of advanced computational tools.
Pressure and Flow Rate Fluctuations in Single- and Two-Blade Pumps
Authors: Pesch Andreas , Melzer Steffen , Schepeler Stephan , Kalkkuhl Tobias , Skoda Romuald 
Published: August 2020

Abstract
A comparative study on the highly unsteady flow field in single- and two-blade pumps is performed. Stationary pump characteristics, as well as pressure and flow rate fluctuations, are presented. Wall pressure fluctuations were measured in the suction and pressure pipe as well as at several locations within the volute casing by piezoresistive transducers. Flow rate fluctuations were evaluated by a recently presented measurement system based on an electromagnetic flowmeter (Melzer et al. 2020, “A System for Time-Fluctuating Flow Rate Measurements in a Single-Blade Pump Circuit,” Flow Meas. Instrum., 71, p. 101675). Measurements were accompanied by three-dimensional (3D) flow simulations with the open-source cfd software foam-extend. A thorough grid study and validation of the simulation were performed. By a complementary analysis of measurement and simulation results, distinctive differences between both pump types were observed, e.g., flow rate and pressure fluctuation magnitudes are significantly higher in the single-blade pump. In relation to the respective mean values, flow rate fluctuation magnitudes are one order lower than pressure fluctuation magnitudes for both pumps. For the two-blade pump, fluctuations attenuate toward overload irrespective of the particular pump circuit, while they rise for the single-blade pump. 3D simulation results yield detailed insight into the spatially and temporally resolved impeller–volute interaction and reveal that the single-blade impeller pushes a high-pressure flow region forward in a way as a positive displacement pump, resulting in an inherently fluctuating velocity and pressure distribution within the volute.
A Comparison of Static and Rotordynamic Characteristics for Two Types of Liquid Annular Seals With Parallelly Grooved Stator/Rotor
Authors: Li Zhigang , Fang Zhi , Li Jun 
Published: August 2020

Abstract
Liquid annular seals with parallelly grooved stator or rotor are used as replacements for smooth plain seals in centrifugal pumps to reduce leakage and break up contaminants within the working fluid. Parallelly grooved liquid annular seals have advantages of less leakage and smaller possibility of abrasion when the seal rotor–stator rubs in comparison to smooth plain seals. This paper deals with the static and rotordynamic characteristics of parallelly grooved liquid annular seals, which are limited in the literature. Numerical results of leakage flow rates, drag powers, and rotordynamic force coefficients were presented and compared for a grooved-stator/smooth-rotor (GS-SR) liquid annular seal and a smooth-stator/grooved-rotor (SS-GR) liquid annular seal, utilizing a modified transient computational fluid dynamics-based perturbation approach based on the multiple-frequency elliptical-orbit rotor whirling model. Both liquid annular seals have identical seal axial length, rotor diameter, sealing clearance, groove number, and geometry. The present transient computational fluid dynamics-based perturbation method was adequately validated based on the published experiment data of leakage flow rates and frequency-independent rotordynamic force coefficients for the GS-SR and SS-GR liquid annular seals at various pressure drops with differential inlet preswirl ratios. Simulations were performed at three pressure drops (4.14 bar, 6.21 bar, and 8.27 bar), three rotational speeds (2 krpm, 4 krpm, and 6 krpm) and three inlet preswirl ratios (0, 0.5, and 1.0), applying a wide rotor whirling frequency range up to 200 Hz, to analyze and compare the influences of operation conditions on the static and rotordynamic characteristics for both the GS-SR and SS-GR liquid annular seals. Results show that the present two liquid annular seals possess similar sealing capability, and the SS-GR seal produces a slightly larger (∼2–10%) drag power loss than the GS-SR seal. For small rotor whirling motion around a centered position, both seals have the identical direct force coefficients and the equal-magnitude opposite-sign cross-coupling force coefficients in the orthogonal directions x and y. For all operation conditions, both the GS-SR and SS-GR liquid annular seals possess negative direct stiffness K and positive direct damping C. The GS-SR seal produces purely positive Ceff throughout the whirling frequency range for all operation conditions, while Ceff for the SS-GR seal shows a significant decrease and transitions to negative value at the crossover frequency fco with increasing rotational speed and inlet preswirl. From a rotordynamic viewpoint, the GS-SR liquid annular seal is a better seal concept for pumps.
Damage Severity Estimation of Timber Poles Using Stress Wave Propagation and Wavelet Entropy Evolution
Authors: Bandara S. , Rajeev P. , Gad E. , Sriskantharajah B. 
Published: August 2020

AbstractTimber poles are widely used in electricity transmission and telecommunication sectors throughout the world. The stress wave propagation for the condition assessment of timber poles is identified as a promising non-destructive testing (NDT) technique due to its simplicity and cost-effectiveness compared to other traditional methods. In this paper, a novel damage severity evaluation criterion for timber poles is proposed on the basis of short-time wavelet entropy of the reflected stress waves. The stress waves are generated by transverse impacts close to the ground level of the pole. The reflected stress waves are recorded and processed in the time frequency domain using the discrete wavelet transform. The decomposed signal components using discrete wavelet analysis are used to determine the wavelet entropy. The wavelet entropies of intact and damaged poles are compared to obtain the relative wavelet entropy (RWE) for damage severity estimation. Further, a numerical model for an in situ pole system is developed to simulate the transverse stress wave propagation and to evaluate the capability of the proposed defect severity estimation method. The developed numerical model is validated with experimental data from controlled testing and the data from field tests. The validated numerical model is then used to simulate different defect scenarios. The wavelet entropy is sensitive to the damage severity in timber poles and can be used as an effective tool to evaluate the severity of damages.