Melamine integrated metal phosphates as non-halogenated flame retardants: Synergism with aluminium phosphinate for flame retardancy in glass fiber reinforced polyamide 66

An integrated multicomponent molecule, Melamine-poly(aluminium phosphate) (Safire^®200), its zinc and magnesium analogues namely Safire^®400 and Safire^®600 respectively were used as flame retardants for glass fiber reinforced polyamide 66 in combination with aluminium phosphinate. Characterisation, thermal stability, combustion properties, glow-wire flammability index and glow-wire ignition temperature and cone calorimetry results are reported. Lower threshold of loading of flame retardants that pass V0 rating in UL-94 vertical burning test have been determined. Effect of Zinc borate (Firebrake^®500 grade) in these formulations was investigated. Influence of additives on endothermic and exothermic transitions of polyamide 66 in these formulations were studied by differential scanning calorimetry. The formulations were evaluated against the properties and fire performances of classical commercial combination of aluminium phosphinate and melamine polyphosphate. All the new formulations down to 15% of additives loading achieve V0 rating according to UL-94 protocol. This synergistic combination of additives significantly reduces the peak of heat release rate (pHRR) and total heat release (THR) in formulations exhibiting various degrees of intumescence.     

Compressive sensing: a strategy for fluttering target discrimination employed by bats emitting broadband calls

When foraging, so-called FM-bats emit sequences of frequency modulated (FM) calls in order to detect, identify, and localize edible prey. Once a potential target has been detected, various call and call sequence parameters, such as frequency sweep, pulse duration, and inter pulse interval (IPI) vary. In this paper, the possible functions of the variation of the IPI are studied. In particular, it is conjectured that the IPI patterns are an adaptive behavior that optimizes the signal design parameters in order to improve information retrieval. Such an irregular sampling strategy would be useful whenever bats need to characterize signal modulation (e.g., the wing beat of an insect) using a call emission rate lower than the signal modulation of interest. This problem can be recast as extracting features, in this case the joint acoustic and modulation frequency representation, from signals sampled at frequencies well below the Nyquist cut-off frequency. To study the possibility of such target classification using a sub-Nyquist sampling scheme, results derived in the context of compressive sensing are used. Processing echoes collected from both rotating computer fans and fluttering locusts, it is shown that such a strategy would allow FM-bats to discriminate between targets based on their different fluttering rates.     

Competitive Salt Precipitation/Dissolution During Free‐Water Reduction in Water‐in‐Salt Electrolyte

Water‐in‐salt electrolytes based on highly concentrated bis(trifluoromethyl)sulfonimide (TFSI) promise aqueous electrolytes with stabilities nearing 3 V. However, especially with an electrode approaching the cathodic (reductive) stability, cycling stability is insufficient. While stability critically relies on a solid electrolyte interphase (SEI), the mechanism behind the cathodic stability limit remains unclear. Now, two distinct reduction potentials are revealed for the chemical environments of free and bound water and that both contribute to SEI formation. Free water is reduced about 1 V above bound water in a hydrogen evolution reaction (HER) and is responsible for SEI formation via reactive intermediates of the HER; concurrent LiTFSI precipitation/dissolution establishes a dynamic interface. The free‐water population emerges, therefore, as the handle to extend the cathodic limit of aqueous electrolytes and the battery cycling stability.     

Lateral Waveguiding Properties of VCSELs for Integrated Optical Monitoring

We have investigated experimentally the optical behaviour of a Vertical-Cavity Surface-Emitting Lasers (VCSEL) when it is used as a lateral waveguide. This provides a better understanding of the mechanisms involved in VCSEL optical power monitoring by integrated lateral detection. The lateral optical spectra as well as the waveguide transmission spectrum have been measured. Their analysis and comparison demonstrate that the lateral signal is mostly coming from the spontaneous emission escaping laterally from the VCSEL and that light is filtered during the propagation and detection processes. This allows us to explain previous results obtained in two different configurations of lateral detection. These results are useful to optimize the lateral detection performances for concrete applications in monitoring or telemetry systems.     

High repetition rate spiker-sustainer XeCl laser

An X-ray preionized spiker-sustainer XeCl-excimer laser operating at high repetition frequency (1000 Hz) and 220 W of average laser power is demonstrated. The pulse energy and the pulse duration (160 ns) are virtually independent of the repetition frequency. Comparison with aC-L-C circuit shows superior properties of spiker-sustainer excitation for high-frequency operation. Furthermore, a variation of the overshoot mode is proposed.     

Measurement of np and pp asymmetry with an accelerated polarized deuteron beam from 725 to 1000 MeV per nucleon

The accelerated polarized deuteron beam of Saturn II was used to measure the analyzing power for np elastic scattering at five energies. The left-right asymmetries ε = (L + R)/(L + R) for np and for pp elastic scattering were measured simultaneously by CH₂? carbon subtraction using one of the beam-line polarimeters. The analyzing power A_00n0(np) is given by the ratio ε_np^d/ε_pp^d multiplied by the known analyzing power for pp elastic scattering. Experimental evidence is consistent with the underlying assumption that in the kinetmatic region of the experiment the ratio of the np to pp analyzing powers for scattering of quasifree nucleons in deuterons is the same as for scattering of free neutrons and protons, respectively.     

An experimental study of a broadband active attenuator for cancellation of random noise in ducts

A broadband active attenuator for cancellation of plane wave duct noise has been demonstrated. Reductions of 16–20 dB RMS were achieved with random noise over the bandwidth 30–650 Hz, and 20 dB with transient noise. A two-microphone and two-loudspeaker unidirectional coupler arrangement was employed in the attenuator, with loudspeaker motional feedback, and a transversal filter which corrected residual amplitude and phase errors.     

Contribution to the development of atmospheric radioxenon monitoring

Within the frame of Comprehensive Nuclear-Test Ban Treaty (CTBT), this paper deals with the development of the new techniques necessary for the xenon monitoring requested by the CTBT. An automatic system called SPALAX™, devoted to the on-site sampling and measurement was developed by French atomic energy commission (CEA). Analytical methods and equipments have been studied at our laboratory, using dual X-γ-spectrometry in order to get independent means with better sensitivity within a robust quality assurance program. In the case of a wide number of potential existing sources and depending on meteorological conditions, several solutions can be arrived at.