Assessing the broadband absorption properties of micro-capillary plates through modelling and experimental studies

The 179th Meeting of the Acoustical Society of America, 7-11 December 2020, on-line Noise: Paper 1aNSa3 12 páginas, 10 figuras, 1 tablaHelmholtz-type resonance absorbers constitute noise control devices widely used in many areas that have attracted attention in the last years due to the advancement of acoustic metamaterials. Micro-perforated panels placed over a backing cavity work on the same principle at low frequencies. They can provide important absorption values but confined in a narrow frequency band. To overcome this limitation, unbacked configurations have been considered, but care has to be taken for a proper selection of their constitutive parameters. In this work, freestanding micro-perforated plates with holes diameters down to 10 micrometers and high perforation ratio are shown to be good candidates as wideband low-frequency sound absorbers. Several micro-capillary plates, classified as a function of the Knudsen number, are studied analytically and experimentally. Most of the porous microsystems that use gases work in slip-flow regime whose properties differ considerably from the classical continuum regime. Results showed that unbacked micro-capillary plates can achieve absorption values greater than 0.7 up to 7 kHz with an absorption plateau above 0.85 up to 4 kHz under normal incidence. Dependence of their performance to the backing load is analyzed. They could be used as low-frequency noise dissipation devices with applications as calibrated anechoic terminations.This study was funded in Spain by the Ministerio de Economía y Competitividad project TRA2017- 87978-R, AEI/FEDER, UE, and the mobility program ILINK+2018. It was supported in France by the ANR VIRTECH (ANR-17-CE10-0012-01).Peer reviewe

Model for active control of flow-induced noise transmitted through double partitions

The results are presented of a study concerned with the prediction of the airflow noise transmitted through an element of the fuselage structure: a doublepanel of finite extent that consists of a pair of thin elastic plates containing a light insulating material separated from the inner skin by an air gap. This configuration is representative of typical compound sidewalls in large commercial aircraft. A solution based on modal coupling is obtained and validated by comparisons with other solutions on various test cases. A physical interpretation is given for the calculated vibroacoustic response of a double partition system excited by a turbulent boundary layer, and the effect of an air gap between the insulation facing bag and the trim panel is analyzed. It is shown that the levels of the inwardly radiated sound power are mainly determined by the contribution of the first skin panel-controlled mode, and the added damping effect due to the insulating material has little effect below this resonance. To achieve sound reduction in the very low-frequency domain, the performance of various active control strategies are examined and compared. It is found that the most efficient strategy is the suppression of the low-order skin panel structural modes. However, we note that significant reductions in the sound power radiated can also be achieved by the active suppression of the low-order structural modes of the trim panel

Cost-efficient characterization of the aeroacoustic performance of micro-perforated wall-treatments in a wind tunnel

179th Meeting of the Acoustical Society of America, 7-11 December 2020, on-line. Noise: Paper 1aNSa4 12 páginas, 18 figuras, 1 tablaMitigating the propagation of low frequency noise in ducted flows represents a challenging task since wall treatments have often limited dimensions. Micro-perforated panels have been successfully used backed by a cavity constituting a bulk-reacting resonator or in combination with honeycomb for a locally-reacting system. In this work, a cost-efficient methodology for the study and characterization of the aero-acoustic properties of flush-mounted micro-perforated resonators has been developed. Although Laser Doppler Ve- locimetry is a non-intrusive technique, it requires delicate instrumentation to obtain an estimation of the acoustic velocity and pressure fluctuations at several points over a wall liner. Here, the attenuation has been estimated from sound pressure level measurements performed with two nosecone microphones positioned along a vertical line centered on the resonator axis. Experiments have been performed in a wind tunnel in presence of a low-speed turbulent boundary layer of air fully developed over different samples made up of micro-perforated sheets or porous materials with surface roughness. The micro-perforates have been flush- mounted over a cylindrical cavity of depth 30 mm situated on the floor of the test section. The ability of bulk-reacting resonators for reducing the acoustic or flow-induced noise has been assessed in comparison with locally-reacting treatmentsThis study was funded in Spain by the Ministerio de Economía y Competitividad project TRA2017- 87978-R, AEI/FEDER, UE, and the mobility program ILINK+2018. It was supported in France by the programme A*MIDEX Excellence Initiative of Aix-Marseille University in the framework of the LabeX Mechanics and Complexity AAP2 and by the ANR VIRTECH (ANR-CE10-0012-01). The authors would like to thank A. Ouaked (Master student) for the source-induced measurements.Peer reviewe

Active control of the flow-induced noise transmitted through a panel

Active control of sound transmitted through an elastic panel when excited by a turbulent boundary layer is investigated. The motivation is the control within an aircraft cabin of the flow-induced noise due to the wall-pressure fluctuations over the fuselage. The excitation is random and so the plate velocity and the radiated sound pressure must be described by spectral densities. These quantities can be obtained from an analysis of the response of the system to a harmonic deterministic excitation and a statistical model for the turbulent boundary layer. Criteria are discussed under which the cross-modal coupling of the structural modes can be neglected when excited by a turbulent boundary layer. When considering subsonic turbulent flows, parametric studies show that each structural mode radiates sound independently. Hence, a suitable strategy for the active structural acoustic control of the sound power transmitted through the panel would be independent feedback control of each structural mode of the system in the low-frequency domain. The performance of this active control strategy is compared to that obtained by controlling the radiation modes of the panel for different numbers of control channels

Frontline Consolidation with Blinatumomab for High-Risk Philadelphia-Negative Acute Lymphoblastic Adult Patients. Early Results from the Graall-2014-QUEST Phase 2

International audienceIntroduction: Philadelphia chromosome (Ph)-negative acute lymphoblastic leukemia (ALL) with high-risk genetics and/or measurable residual disease (MRD) are at high-risk of disease recurrence. In the previous GRAALL-2005 study, we identified KMT2A rearrangements (KMT2A-r), IKZF1 intragenic deletion (IKZF1del) and post-induction (TP1, week 6) MRD ≥ 0.01% as independent factors to predict relapse in Ph-negative B-cell precursor (BCP) ALL (Beldjord K, Blood 2014). In the GRAALL-2014 trial, high-risk (HR) patients were thus defined by the presence of at least one of these three factors. Among them, only those with higher MRD levels defined as TP1-MRD ≥ 0.1% and/or week 12 (TP2) MRD ≥ 0.01% were considered at very high risk (VHR) and proposed allogeneic hematopoietic stem cell transplant (alloSCT) in first remission (Dhedin et al., Blood 2015). Since October 2018, all these patients were eligible to be included in the GRAALL-2014-QUEST phase 2 study to receive blinatumomab as part of consolidation and maintenance phases or as a bridge to transplant. Methods: From October 2018 to December 2020, 95 patients with high-risk Ph-negative BCP-ALL without central nervous system involvement at diagnosis and in continuous complete remission after induction and consolidation 1, were prospectively included to start blinatumomab at week 12. One patient was excluded because of T-ALL phenotype (with CD19 aberrant expression). Patients with alloSCT indication and a stem cell source received blinatumomab 28 microg/d administered by continuous intravenous infusion (cIV) until transplant. A minimum of 4 weeks blinatumomab was recommended before proceeding to transplantation. All other patients received 5 cycles of blinatumomab 28 microg/day cIV (for 28 days), during consolidation 2 and 3 and at months 1/3/5 of the maintenance phase respectively. The primary objective was disease-free survival (DFS). Secondary objectives included post-blinatumomab MRD response at TP3 (after consolidation 2 or before alloSCT), overall survival (OS), and safety. Early results are reported here. Results: Median age was 35 years old (range, 18-60). Median white blood cell count (WBC) at diagnosis was 12 G/L (range, 1-449). Oncogenetic analyses allowed classifying ALL as Ph-like (18%), KMT2A-r (17%), DUX4/ERGdel (13%), ZNF384-r (11%), low hypodiploidy/near triploidy (7%), B-other (26%) or unknown (9%). An IKZF1del was found in 37/93 (40%). A TP1-MRD ≥ 0.01% was found in 46/94 patients (49%). Final risk group was HR for 45 patients and VHR for 49 patients. Last pre-blinatumomab MRD was <0.01% in 49/88 (56%) of evaluable patients. A total of 40 patients (42%) received an alloSCT. The median number of blinatumomab cycles received in patients not proceeding to alloSCT was 4 cycles (range, 1-5). Thirty-nine severe adverse events (SAEs) were reported: 1 CRS (grade 2), 8 neurotoxicities (1 grade 2, 3 grade 3, 3 grade 4, 1 grade 5), 19 infections, and 11 others. The only grade 5 SAE occurred after alloSCT (seizures). After blinatumomab, a complete MRD response (with at least 0.01% sensitivity) was achieved in 61/82 (74%) evaluable patients and in evaluable patients with pre-blinatumomab detectable MRD. MRD response to blinatumomab was lower in patients with high pre-blinatumomab MRD level, while not impacted by age, WBC, or oncogenic subgroup. With a median follow-up of 20 months, 18-month DFS and OS was 78.8% (95% CI [66.9-86.8]) and 92.1% (95% CI [83.2-96.4]) respectively (Figure 1). Patients with VHR diseases had a worse DFS (68.8%, 95% CI [51.1-81.2]) as compared to other patients (90.6%, 95% CI [72.1-97.1]); p=0.018). This difference of DFS was abrogated by censoring patients at transplant (VHR 88.1%, 95% CI [65.5-96.3] versus others 90.6%, 95% CI [72.1-97.1%], p=0.10). Other factors significantly associated with better DFS were DUX4/ERGdel subgroup, low pre-blinatumomab MRD, and complete MRD response after blinatumomab. Conclusion. In patients wih high-risk BCP-ALL, blinatumomab added to consolidation is safe and gives promising results. A comparison to similar patients treated in the same GRAALL-2014 study before October 2018 is planned with a longer follow-up. Figure 1 Figure 1. Disclosures Boissel: Novartis: Consultancy, Honoraria, Research Funding; Incyte: Honoraria; Amgen: Consultancy, Honoraria, Research Funding; SANOFI: Honoraria; Servier: Consultancy, Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; CELGENE: Honoraria; JAZZ Pharma: Honoraria, Research Funding; PFIZER: Consultancy, Honoraria. Huguet: Novartis: Other: Advisor; Jazz Pharmaceuticals: Other: Advisor; Celgene: Other: Advisor; BMS: Other: Advisor; Amgen: Other: Advisor; Pfizer: Other: Advisor. Rousselot: Incyte, Pfizer: Consultancy, Research Funding. Chalandon: Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Amgen: Other: Advisory Board; Incyte: Speakers Bureau; Incyte, BMS, Pfizer, Abbie, MSD, Roche, Novartis, Gilead, Amgen, Jazz, Astra Zenec: Other: Travel EXpenses, Accomodation. Delabesse: Astellas: Consultancy; Novartis: Consultancy. Dombret: Abbvie: Honoraria; Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; NOVARTIS: Research Funding; pfizer: Honoraria, Research Funding; servier: Research Funding; BMS-Celgene: Honoraria; Daiichi Sankyo: Honoraria. OffLabel Disclosure: Blinatumomab in frontline high-risk acute lymphoblastic leukemi

Blinatumomab during Consolidation in High-Risk Philadelphia Chromosome (Ph)-Negative B-Cell Precursor (BCP) Acute Lymphoblastic Leukemia (ALL) Adult Patients: A Two-Cohort Comparison within the Graall-2014/B Study

International audienc