Institut National de Recherche et de Sécurité

Adjusting the assistive torque of upper limb occupational exoskeletons is essential to optimize their effectiveness and user acceptance in companies. This adjustment enables a balance to be struck between the expected benefits and potential undesirable effects associated with their use, particularly for the shoulder joint, which is sensitive to the balance of forces. Despite this, no study has yet evaluated these assistive torques in static and dynamic conditions representative of work situations. The aim of this article is therefore to evaluate these assistive torques under these two conditions, using an isokinetic dynamometer. Angular velocities ranging from 0 to 240°/s and four levels of assistance were investigated. The results showed that the maximum assistive torques in flexion (energy restitution phase) were lower than those in extension (tensioning phase) by 20 to 36% and were median in static conditions. It was also observed that the level of assistance and the exoskeleton opening angles had a strong impact on the assistive torques, unlike the angular velocity in dynamic conditions, which had a minimal effect. Quantifying these assistive torques is crucial for assessing their biomechanical impact and adjusting the exoskeleton’s assistance to the operator and the task performed.

Hazardous pollutant containment zones should be maintained at a pressure lower than the outdoor atmospheric pressure to prevent pollutants from escaping to the outdoor environment. However, atmospheric wind conditions can cause breaching of the containment zone that is established through mechanical ventilation. This paper combines external wind pressure (Pe) time series on an internally depressurized building with a carefully designed ventilation network to analyze indoor pressure (Pi) and containment breach duration. The Pe data are obtained by wind-tunnel (WT) tests and computational fluid dynamics (CFD) simulations of large-eddy simulation (LES) and scale-adaptive simulation (SAS). The objectives of the paper are (1) comparing Pe results by WT and CFD; (2) assessing the impact of Pe uncertainties in CFD on the resulting Pi and breach duration; and (3) estimating Pi and breach duration for an initial case study with indoor depressurization of -40 Pa and reference wind speed (Uref) of 12.65 m/s at building height. The results are discussed in terms of dimensionless pressure coefficients (Cpe and Cpi). It is shown that LES and especially SAS Cpe data deviate substantially from the WT values but that the impact of these CFD uncertainties on Cpi and breach duration remains fairly limited. Deviations for Cpi statistics fall within the experimental uncertainty, and the CFD breach duration deviates generally less than 10% from the WT result. Estimated breach durations for Uref = 12.65 m/s, however, can go up to 80% in spite of the −40 Pa depressurization, stressing the importance of this type of studies.

Enniatins (ENNs) and beauvericin (BEA) are cyclic hexadepsipeptide fungal metabolites which have demonstrated antibiotic, antimycotic, and insecticidal activities. The substantial toxic potentials of these mycotoxins are associated with their ionophoric molecular properties and relatively high lipophilicities. ENNs occur extensively in grain and grain-derived products and are considered a food safety issue by the European Food Safety Authority (EFSA). The tolerable daily intake and maximum levels for ENNs in humans and animals remain unestablished due to key toxicological and toxicokinetic data gaps, preventing full risk assessment. Aiming to find critical data gaps impeding hazard characterization and risk evaluation, this review presents a comprehensive summary of the existing information from in vitro and in vivo studies on toxicokinetic characteristics and cytotoxic, genotoxic, immunotoxic, endocrine, reproductive and developmental effects of the most prevalent ENN analogues (ENN A, A1, B, B1) and BEA. The missing information identified showed that additional studies on ENNs and BEA have to be performed before sufficient data for an in-depth hazard characterisation of these mycotoxins become available.

Background Octylisothiazolinone (OIT; CAS 26530–20‐1) is used as a biocide in leather products. Objectives To report several cases of allergic contact dermatitis (ACD) from the use of headphones containing OIT, and to highlight the strong allergic potential of this preservative. Patients and Methods Four patients with ACD from headphones were patched tested using the European baseline, cosmetic, rubber, plastics/glues and acrylates series. Patients were also tested to different parts of their own headphones (‘as is’). Chemical analyses of the headphones was additionally performed with Ultra Performance Liquid Chromatography—tandem mass spectrometry (UPLC‐MS/MS). Results All patients had developed localised ACD to the contact sites of the headphones, except for one patient who developed ‘angioedema‐like’ dermatitis. All patients were shown to have been primarily sensitised to OIT. UPLC‐MS/MS analysis confirmed OIT in the leather ear pads of the headphones. Conclusions OIT is a relevant and strong sensitizer in leather, and may cause severe ACD. Safer use concentrations (limits) of OIT, as well as product labelling in the leather industry, may be required to ensure a better protection of consumers.

Recording speech is often a matter of proper experimental design to obtain the best signal quality. This notably includes appropriate microphone positioning and gain adjustment. However, some radio communication devices require that the microphone be placed in a very close proximity to the mouth, therefore capturing the respiratory airflow, as well as the air bursts from plosive consonants. In this paper, we assess an objective evaluation method for the quality of speech signals captured in such adverse conditions. It employs an artificial mouth coupled with a steady airflow to compute the Speech Transmission Index (STI). We apply this method to the evaluation of four commercially available pop filters. The addition of a 30~L/min airflow reduces the STI with the microphone alone from excellent to fair. With soft fabric filters, we gain back the original STI, while it remains very slightly degraded with a metal mesh filter. The objective metric is finally confronted with a listening test. The perceived quality of simulated samples with the added airflow is similar to the STI results. However, no significant difference between the filters is found with real speech samples containing plosive consonants and no respiration noise.

Although urban combat is nothing new, recent conflicts have shed light on Western armies' difficulties when operating in such environments. Thus, new surveillance and hazard detection challenges in complex environments are addressed. A new decision aid tool for acoustic sensor positioning has been developed to improve reconnaissance performance. The software's sensor location optimization kernel is based on a genetic algorithm developed by our partners from FKIE. It resolves successive localization problems using pre-computed Times Of Arrival (TOA) between an impulsive acoustic source and various surveillance microphones. The present study discusses the pertinence of the Time-Domain Finite-Element Method (TD-FEM) to simulate wave propagation within an urban area to obtain TOA and resolve localization problems. The approach is compared to experimental measurements in an urban area, and the pros and cons of the TD-FEM for this configuration are discussed.

Bone conduction microphone (BCM) which records speech that travels through at least one human tissue, demonstrates a significant advantage in capturing voice in noisy environments. The ergonomic design and versatile placement options of BCMs further enhance their utility, allowing integration with various head equipment such as earplugs, glasses, helmets, or NRBC masks. Despite these advantages, ensuring the quality and intelligibility of recorded speech remains a challenge. Past efforts have involved various post-treatments uniformly applied to all signals, to address these drawbacks, with limited success. In this paper, we introduce a novel approach aimed at enhancing BC speech quality by implementing a select number of filters grounded in speech production principles. In this study, treatments both dependent and independent of phonemes are applied. Subjective tests are conducted to assess the efficacy of these filters and compare their effects.

The performances of Hearing Protection Devices (HPD) facing high-level impulse noises is limited by the transmission through the protector. This transmission can be evaluated by measuring the earplug's displacement along the ear canal axis. Previous measurements highlighted a displacement proportional to the peak acoustic pressure in the protected ear canal. To better understand the consequences on the HPD performances, this evaluation requires to be extended. Thus, various configurations are studied with Acoustic Test Fixture (ATF) external ears and earplugs of low and medium hardness. The earplug's peak displacements have been measured with a laser-vibrometer and the acoustic pressure with the ATF microphone. The impulse waves employed to excite the earplugs ranged from 150 dB to 180 dB peak. A medium hardness earplug inserted in a low hardness ear led to the worst performances with a plug displacement of 200 µm and a peak noise reduction of 17.8 dB(SPL) for an impulse noise of 177 dB(SPL). For the best case, a maximum displacement of 66 µm and peak noise reduction of 28.8 dB(SPL) have been measured. These results suggest new perspectives to improve the HPDs but also their evaluation through the choice of judicious ATF materials that conform to biological tissues.

The technical implementation of a single-input multiple-output (SIMO) active near-field noise control (ANC) system designed for global low-frequency noise control is presented. The SIMO control strategy is motivated by noise control simulations based on a direct boundary element method (BEM) ansatz formulated in this paper. The suitability of the chosen BEM formulation and SIMO control strategy is accompanied and confirmed by extensive experiments and comparison to analytical calculations based on isotropic sources. The influence of parameters such as the positioning of the error microphone, the membrane velocity required for optimal global reduction, the effects of phase inaccuracies and the number of actuators on global reduction are investigated. The real-time control of the SIMO system is technically implemented on field programmable gate array (FPGA) hardware using a frequency domain block FxLMS algorithm. The iterative algorithm converges in less than 0.1 s for the examined frequency range from 100 Hz to 1000 Hz. Measurements using various circular SIMO array configurations showed reductions in sound power of up to 85\%, aligning closely with the numerical results.

Occupational exoskeletons hold promise in preventing musculoskeletal disorders, but their effectiveness relies on their long-term use by workers. This study aims to characterize the adoption process of occupational exoskeletons by analyzing the experiences of 25 operators. Using a mixed-methods approach, both quantitative and qualitative data were collected before and during a four-week familiarization period. We primarily focused on users’ expectations, subjective assessments over time, and initial experiences. Findings elucidate shifts in operators’ perceptions of the devices over time. Through their narratives, we highlight how exoskeleton use impact operators’ movements and the subsequent adaptations. Operators demonstrated diverse exploratory behaviors, indicating their efforts to get to grips with the effects of exoskeletons in their own ways. This study offers insights into the initial stages of occupational exoskeleton adoption, thus enriching our comprehension of rejection patterns and pathways toward their widespread acceptance.

Advancements in indoor pollutant sensor networks have revolutionized spatio-temporal cartography, making it an essential tool for evaluating and preventing pollution exposure risks in occupational environments. In this study, we introduce a new spatio-temporal cartography technique that leverages the inherent smoothness of gas diffusion concentrations in both space and time. Our approach explicitly accounts for the temporal coherence and non-negativity of pollutant concentration maps, resulting in more interpretable estimates. We demonstrate the efficacy of our approach using real carbon dioxide (CO2) data collected during experiments at the Institut National de Recherche et Sécurité (INRS) in Nancy.

Considered to be the next-generation (NextG) Internet, the Metaverse faces various security risks inherited from its predecessor and new specialized threats. It is even more challenging to mitigate these issues in a large-scale setting with numerous wearable devices such as augmented, virtual reality (AR/VR) headsets. In this article, we aim to analyze the security aspect of the Metaverse thoroughly, focusing on blockchain and machine learning (ML) solutions. Firstly, we present a 4-layer architecture of the Metaverse and discuss potential solutions for Metaverse security based on blockchain and ML. Next, we develop a decentralized collaborative intrusion detection system (CIDS) based on blockchain and federated learning (FL) that allows such the Metaverse users to collaboratively protect this digital world. This helps solving the scalability and single-point-of-failure (SPoF) issues of traditional security approaches. Finally, we outline some key challenges and discuss future research directions for Metaverse security.

In this paper, a first demonstration of the optical triggering of a 10 kV 4H-SiC Bipolar Junction Transistor is reported. A laser emitting UV (349 nm) has been used for the generation electron-hole pairs within the device. A current density of about 20 A.cm⁻² has been obtained. This low value in comparison with 100 A.cm⁻² for “conventional” BJT is due to the narrow pulse width (5 ns). The current waveform shows the effect of the carrier lifetime in the base and collector regions. From these measurements, we have extracted the IC (VCE) characteristics for different laser optical power and the switch-on time which is about 1 µs.