Abstract: A ventilated helmet is provided. The helmet includes a shell defining a cavity, the shell having a front section provided with an opening to allow the wearer to see. The helmet also includes a transparent shield adapted having an inner surface and being adapted to substantially close the opening. Finally, the helmet includes a ventilation system having an evacuation subsystem adapted to create an evacuation airflow to evacuate humid air within the cavity to a surrounding environment. The ventilation system further has a pressurizing subsystem adapted to admit a pressurizing airflow within the cavity to create a high-pressure zone and a low-pressure zone within the cavity, wherein when in use, the wearer exhales air within the low-pressure zone, and wherein the high-pressure zone prevents air within the cavity from travelling from the low-pressure zone to the high-pressure zone. A method of evacuating humid air from the cavity is also provided.

Abstract: Propulsion system (2) for a helicopter (1) comprising a main engine (9), a main rotor (3), a main gearbox (4) including an output mechanically connected to the main rotor (3), a reduction gearbox (13) mechanically coupled between the main engine (9) and a first input of the main gearbox (4), and an assistance device (10). The assistance device (10) comprises a first electric machine mechanically coupled to the reduction gearbox (13) and configured to operate as an electric generator to take off energy produced by the main engine (9), and a second electric machine mechanically coupled to a second input of the main gearbox (4), the second electric machine being supplied with electrical power by the first electric machine and configured to operate as an electric motor to deliver additional mechanical power to the main gearbox (4).

Abstract: A ventilated helmet is provided. The helmet includes a shell defining a cavity, the shell having a front section provided with an opening to allow the wearer to see. The helmet also includes a transparent shield adapted having an inner surface and being adapted to substantially close the opening. Finally, the helmet includes a ventilation system having an evacuation subsystem adapted to create an evacuation airflow to evacuate humid air within the cavity to a surrounding environment. The ventilation system further has a pressurizing subsystem adapted to admit a pressurizing airflow within the cavity to create a high-pressure zone and a low-pressure zone within the cavity, wherein when in use, the wearer exhales air within the low-pressure zone, and wherein the high-pressure zone prevents air within the cavity from travelling from the low-pressure zone to the high-pressure zone. A method of evacuating humid air from the cavity is also provided.

Abstract: A photonic millimeter-wave oscillator is based on a heterodyne beatnote of two continuous wave lasers and is configured to provide a narrow linewidth output when the frequency difference is disciplined with rotational spectroscopy of molecules using frequency modulation spectroscopy.

Abstract: Example ultra narrow linewidth Brillouin lasers are disclosed that are pumped by pump lasers that are controlled via optimal control schemes in order to stabilize the Brillouin laser output frequency and minimize the Brillouin output linewidth. The control schemes are based on feedback loops to match the pump laser frequency to the optimum Stokes shift on the one hand and to line-narrow the pump laser linewidth on the other hand via comparing the linewidth of the pump laser with the linewidth of the Brillouin laser. The feedback loops in the control schemes can be partially or fully replaced with feedforward control schemes, allowing for larger bandwidth control. Provision for simultaneous oscillation of the Brillouin lasers on two polarization modes allows for further line-narrowing of the Brillouin output.

Abstract: Disclosed is a fire-fighting device, which includes a casing that delimits an inner cavity in which at least one dispersible fire-extinguishing agent is deposited, and pyrotechnics suitable for generating an explosion causing the casing to rupture and the fire-extinguishing agent to be dispersed. The pyrotechnics include at least one explosive charge, generating the explosion, and a detonator for triggering the explosion of the at least one explosive charge. The detonator includes an ignition device designed to trigger, when in an active state, the explosion of the at least one explosive charge, and an impact sensor designed to detect a mechanical impact received by the device and to bring the ignition device to the active state upon detection of the mechanical impact.

Abstract: Hybrid turbomachine comprising an electric generator, a gas generator equipped with an air inlet and with an exhaust and an acoustic monitoring system comprising a control unit and a plurality of loudspeakers. At least a first loudspeaker is disposed on the electric generator, and/or at least a second loudspeaker is disposed on the air inlet of the gas generator, and/or at least a third loudspeaker is disposed on the exhaust of the gas generator. The control unit of the acoustic monitoring system is mounted on the electric generator and is configured to make an AC-DC electrical conversion of the electromotive force of the electric generator into an adjustable DC voltage intended to be distributed to loads or to energy storage means.

Abstract: An aircraft with an electrical network including electrical subnetworks; a turbo generator including a gas turbine, an electricity generator with permanent magnets having phase groups respectively connected to the electrical subnetworks, and, for each phase group, an isolation device; and a control device designed to detect a short circuit in at least one of the phase groups, each phase group in which a short circuit is detected being described as defective and each other phase group being described as healthy and, in response to the detection of the short circuit, to disconnect this defective phase group from its associated electrical subnetwork and to command the shutdown of the gas turbine. The control device is also designed, in response to the detection of the short circuit, to keep each healthy phase group connected to its electrical subnetwork.

Abstract: A propulsion system (1) for a helicopter, comprising a turboshaft engine (2) with a linked turbine and an electric machine (3) capable of operating as an electric motor, the turboshaft engine (2) and the electric machine (3) being capable of driving in rotation at least one main rotor (5) intended to be coupled to a rotating wing (6) characterised in that it comprises means of coupling and decoupling (14) in rotation between a rotor (3a) of the electric machine (3) and a rotor (2a) of the turboshaft engine (2), the means of coupling and decoupling (14) being capable of allowing the rotor (2a) of the turboshaft engine (2) to be driven in rotation with the aid of the electric machine (3), in a first state of the propulsion system (1), and capable of allowing the rotor (2a) of the turboshaft engine (2) and the rotor (3a) of the electric machine (3) to be decoupled in rotation, in a second state of the propulsion system (1).

Abstract: A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter.

Abstract: Systems and methods for precision control of microresonator (MR) based frequency combs can implement optimized MR actuators or MR modulators to control long-term locking of carrier envelope offset frequency, repetition rate, or resonance offset frequency of the MR. MR modulators can also be used for amplitude noise control. MR parameters can be locked to external reference frequencies such as a continuous wave laser or a microwave reference. MR parameters can be selected to reduce cross talk between the MR parameters, facilitating long-term locking. The MR can be locked to an external two wavelength delayed self-heterodyne interferometer for low noise microwave generation. An MR-based frequency comb can be tuned by a substantial fraction or more of the free spectral range (FSR) via a feedback control system. Scanning MR frequency combs can be applied to dead-zone free spectroscopy, multi-wavelength LIDAR, high precision optical clocks, or low phase noise microwave sources.

Abstract: A tunable millimeter-wave signal oscillator includes two phase coherent optical oscillators, a fiber-ring cavity configured to generate two Stokes waves, and a photosensitive element converting the frequency difference of two optical oscillator into a millimeter-wave radiation. A chip-scale form factor millimeter-wave oscillator includes two continuous wave lasers, a plurality of micro-optical-resonators, an optical frequency division mechanism, two optical tunable bandpass filters, and a photosensitive element converting the pulse train of a frequency comb into a millimeter-wave radiation. A millimeter-wave phase noise analyzer includes an optical interferometer, two photosensitive elements, and a fundamental millimeter-wave frequency mixer. A millimeter-wave frequency counter includes an electro-optic optical frequency comb generator, a microwave voltage controlled oscillator, and an optoelectronic phase locked loop.

Abstract: A hybrid propulsion system for a vertical take-off and landing aircraft comprising at least one combustion engine driving an electricity generator, at least one electrical energy storage assembly associated with each electricity generator and defining, with each electricity generator, an energy branch, a plurality of electric motors actuating a same plurality of rotors providing together the propulsion and/or the lift of the aircraft, and an electrical power and distribution unit supplying power to the plurality of electric motors from the electricity generator and/or from the electrical energy storage assembly according to a pre-established flight phase, the system including at least two energy branches having an asymmetric configuration and each supplying power selectively, by means of the electrical power and distribution unit, all or part of the plurality of electric motors, and in that the electricity generators of the combustion engines have between them a power ratio comprised between

Abstract: Systems and methods for precision control of microresonator (MR) based frequency combs can implement optimized MR actuators or MR modulators to control long-term locking of carrier envelope offset frequency, repetition rate, or resonance offset frequency of the MR. MR modulators can also be used for amplitude noise control. MR parameters can be locked to external reference frequencies such as a continuous wave laser or a microwave reference. MR parameters can be selected to reduce cross talk between the MR parameters, facilitating long-term locking. The MR can be locked to an external two wavelength delayed self-heterodyne interferometer for low noise microwave generation. An MR-based frequency comb can be tuned by a substantial fraction or more of the free spectral range (FSR) via a feedback control system. Scanning MR frequency combs can be applied to dead-zone free spectroscopy, multi-wavelength LIDAR, high precision optical clocks, or low phase noise microwave sources.

Abstract: Examples of compact control electronics for precision frequency combs are disclosed. Application of digital control architecture in conjunction with compact and configurable analog electronics provides precision control of phase locked loops with reduced or minimal latency, low residual phase noise, and/or high stability and accuracy, in a small form factor.

Abstract: A downhole borehole cleaning apparatus (10) for recirculating drill cuttings contained in a downhole borehole is provided and has a body (10) having an outer surface for contacting downhole fluid containing said drill cuttings, the downhole fluid comprising a certain pressure within the downhole borehole (16). The body (10) has a pair of bearing surfaces (30U; 30D) spaced apart along the longitudinal axis of the body (10), and the pair of bearing surfaces (30U; 30D) comprise substantially the same maximum outer diameter (d1) which is greater than the maximum outer diameter of the rest (14) of the body (10). Each of the pair of bearing surfaces (30U; 30D) comprises a substantially constant and un-interrupted diameter (d1) around its whole outer circumference for at least a portion of its longitudinal length; this forces all of the drilling fluid to pass around that maximum outer diameter.

Abstract: Examples of compact control electronics for precision frequency combs are disclosed. Application of digital control architecture in conjunction with compact and configurable analog electronics provides precision control of phase locked loops with reduced or minimal latency, low residual phase noise, and/or high stability and accuracy, in a small form factor.

Abstract: Examples of systems and methods for integrated photonic broadband microwave transceivers are disclosed based on integrated coherent dual optical frequency combs. In some cases, when the system is configured as a transmitter, multiple radio frequency (RF) carriers can be generated, which can either be encoded independently, or used for broadcasting the same information into different bands. In some cases, when the system is configured as a receiver, the spectrum of the input signal can be sliced into several spectral segments for low-bandwidth detection and analysis. In some systems, the optics-related functionalities can be achieved via integrated optic technology, for example based on silicon photonics, providing tremendous possibilities for mass-production with significantly reduced system footprint.

Abstract: Examples of systems and methods for integrated photonic broadband microwave transceivers are disclosed based on integrated coherent dual optical frequency combs. In some cases, when the system is configured as a transmitter, multiple radio frequency (RF) carriers can be generated, which can either be encoded independently, or used for broadcasting the same information into different bands. In some cases, when the system is configured as a receiver, the spectrum of the input signal can be sliced into several spectral segments for low-bandwidth detection and analysis. In some systems, the optics-related functionalities can be achieved via integrated optic technology, for example based on silicon photonics, providing tremendous possibilities for mass-production with significantly reduced system footprint.

Abstract: Systems and methods for precision phase noise measurements of radio frequency (RF) oscillators are provided. An RF signal under test can be modulated on a continuous wave (cw) laser carrier frequency via generation of modulation sidebands using an appropriate modulator. A photonic delay line can be implemented as a self-heterodyne detection system for the phase noise, allowing for photonic down-conversion of the phase noise measurement to direct current (DC). The self-heterodyne detection system allows detection outside of any 1/f noise issues. Ultra-low phase noise detection for RF frequencies in a range from below 1 GHz to beyond 100 GHz is enabled with a low noise floor in the whole frequency range. Higher-order modulation sidebands can further reduce the noise floor of the system. Ultra-low noise RF (microwave) output can be generated. The RF signal under test can be generated by a dielectric resonance oscillator or opto-electronic oscillator.