Picanol (Belgium)

ABSTRACT Air‐jet weaving relies on high‐speed air flow to propel the weft yarns through the machine, achieving high insertion rates but at the cost of a significant energy demand. Capturing the interactions between the air jets and the weft yarns, which often have a fuzzy surface structure, is therefore vital in improving the air‐jet weaving process. To achieve this, this work introduces a cost‐efficient method to represent fuzzy staple‐fibre yarns in Computational Fluid Dynamics (CFD) simulations by adapting the Actuator Line Method (ALM). The methodology addresses the drag‐dominated aerodynamic forces acting on the yarn by introducing an upstream velocity sampling procedure. These forces are then introduced in the flow domain in a smooth and continuous manner using the actuator curve embedding principle, allowing relatively coarse mesh resolutions while still providing a correct prediction of the aerodynamic forces. The method is validated numerically through comparison with high‐fidelity fibre‐resolved simulations in uniform flow. Results show maximal errors in the force prediction of approximately in cross flow with narrow force regularization kernels and a force distribution error below while reducing the cell count by two orders of magnitude. Additionally, the methodology was also validated experimentally in non‐uniform flow and the simulations of these jet flow experiments show excellent agreement with the measured aerodynamic forces on the yarns for various orientations and supply pressures. This actuator line approach significantly reduces the computational cost by bypassing the need for microscale flow resolution around fuzzy yarn surfaces. For this reason, it opens the door to large‐scale coupled fluid‐structure interaction (FSI) simulations of the yarn insertion process in air‐jet weaving.

<bold>Objective:</bold> Obstructive sleep apnea (OSA) is treated with continuous positive airway pressure (CPAP). Some patients have residual excessive daytime sleepiness (EDS) under CPAP. Pitolisant reduce significantly EDS. A meta-analysis assessed efficacy and safety of pitolisant (P) vs placebo (pl) to treat EDS in OSA patients using CPAP. <bold>Method:</bold> An individual patient meta-analytical approach was used to analyse to CPAP-treated patients in pivotal Pitolisant trials; a 2-level (study-patient) hierarchical model assuming a random treatment effect was used. Epworth Sleepiness Scale (ESS) and Oxford Sleep Resistance test (OSLER) were co-primary endpoints. Secondary endpoints included EDS-Z scores, fatigue, clinical global impression, and quality of life (QoL). <bold>Results:</bold> 3 randomized controlled trials were identified. Individual patient data came from 423 CPAP-treated patients (pl n=120, P20mg n=183, P40mg n=120). Treatment effects on ESS were -3.20 (95% CI: -4.37, -2.00; P<0.001) and ‑3.57 (95% CI: -4.87, -2.80); P<0.001) for 20mg and 40mg doses. Treatment effects (minutes) for OSLER were 1.24 (95% CI: 0.60, 1.10); P=0.001) and 1.21 (95% CI: 0.06, 1.38); P=0.006). Efficacy was homogeneous across subgroups; P40mg was superior to P20mg for older age (≥50 years) and higher baseline apnea-hypopnea index values (≥15). No significant differences were observed between the two doses across various safety parameters. <bold>Conclusion:</bold> Pitolisant 20 mg and 40 mg were significantly therapeutically superior to placebo in treating residual EDS in patients with OSA who received CPAP on the outcomes for ESS, OSLER, and QoL.

In air-jet weaving looms the yarn is initially accelerated by the main nozzle. To obtain a high yarn velocity a high air velocity is required which results in complex flow patterns. Consequently, predicting the influence of a change in geometry or inlet pressure on the yarn velocity is not straightforward. In this research a fast time-dependent fluid-structure interaction framework is used to model the acceleration of a yarn during launch. Initially, the performance of the framework is assessed by considering a smooth monofilament yarn. A suggestion is also madeand tested to deal with the surface texture of hairy/multifilament yarns.

This paper describes a new method for collision handling of particle based systems moving on sharp edges using intermediate points and correction methods for particles passing these edges. It aims at facilitating the simulation of physically realistic movement of the particles in contact with surfaces, even if those surfaces contain sharp edges. The method was developed in order to increase the range of surfaces that allow valid simulations. The method has for the moment only been applied to the simulation of yarn, which is represented as a one-dimensional system of particles connected by springs and dampers. This could be extended however to two-dimensional systems such as cloth, although the technique is developed for explicit integration schemes. Validation has been done by comparing with surfaces with smoothed edges as well as by comparing with actual high speed camera results. From the results, it was shown that physically realistic movement of yarn over a sharp edge can now successfully be simulated.

How firms scan and interpret their environments has implications for the flexibility strategy that they choose, as well as for the performance of that strategy. We extend Daft and Weick’s (Acad Manage Rev 9(2):284–295, 1984) model of firms as interpretation systems into a theoretical model of flexibility performance through extended iterations between observations of a failed flexibility initiative and relevant literature. We test the model using well-known teaching cases. We argue that the use of an iterative process that involves cases and theory both stimulates creativity in integrating theory and lays an initial foundation for evidence-based practice.

The design and optimization of a high-speed low-voltage CMOS flash analog-to-digital converter (ADC) are presented. The optimization procedures used during the design give the needed specifications of the different building blocks. Also, an extensive description of the implemented digital error correction technique is described. The used analog power supply is only 1.8 V. The maximum sampling speed is 1.3 GHz. The signal-to-noise-plus-distortion ratio (SNDR) at 133 kHz is 33.2 dB, and the SNDR at 500 MHz is 32 dB. The total power consumption of the converter at full speed is 600 mW and the total active area is only 0.13 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The ADC is implemented in a 0.25-μm pure digital CMOS technology.