Power harvesting in a helicopter lag damper

In this paper a new power harvesting application is developed and simulated. Power harvesting is chosen within the European Clean Sky project as a solution to powering in-blade health monitoring systems as opposed to installing an elaborate electrical infrastructure to draw power from and transmit signals to the helicopter body. Local generation of power will allow for a ‘plug and play’ rotor blade and signals may be logged or transmitted wirelessly.\ud The lag damper is chosen to be modified as it provides a well defined loading due to the re-gressive damping characteristic. A piezo electric stack is installed inside the damper rod, effec-tively coupled in series with the damper. Due to the well defined peak force generated in the damper the stack geometry requires a very limited margin of safety. Typically the stack geometry must be chosen to prevent excessive voltage build-up as opposed to mechanical overload.\ud Development and simulation of the model is described starting with a simplified blade and piezo element model. Presuming specific flight conditions transient simulations are conducted using various power harvesting circuits and their performance is evaluated. The best performing circuit is further optimized to increase the specific power output. Optimization of the electrical and mechanical domains must be done simultaneously due to the high electro-mechanical cou-pling of the piezo stack. The non-linear electrical properties of the piezo material, most notably the capacitance which may have a large influence, are not yet considered in this study.\ud The power harvesting lag damper provides sufficient power for extensive health monitoring systems within the blade while retaining the functionality and safety of the standard component. For the 8.15m blade radius and 130 knots flight speed under consideration simulations show 7.5 watts of power is generated from a single damper

Power harvesting using piezomaterial in a helicopter rotor blade

Current power harvesting research has focused on bending beams and determining power output under a given excitation. For the European CleanSky – Green Rotor Craft project a tool is being developed which optimizes the piezoelectric material and placement thereof for power harvesting. It focuses on beam-like structures exhibiting more complex dynamics where the optimum configuration is not evident. In particular helicopter rotor blades are considered where strains are high and frequencies low, stepping away from typical high frequency / low strain harvesting applications. This application will allow for smart rotor blades, alleviate rotor induced vibrations, subsequently increasing comfort and possibly airframe longevity. First an uncoupled model was developed, using an airfoil shape and vibration input from industry. The blade surface is covered with piezo electric patches of which the strain during one cycle is calculated. Materials, either ceramic or piezo polymer, are selected based on a peak strain criterion and the energy of each patch is then evaluated using a specified harvesting circuit. Optimum locations are determined using a minimum desired efficiency relative to the best performing patch. For aircraft application the main performance indicator is clearly the power to weight ratio. Experiments have also been conducted which confirm the piezo polymer performance up in\ud the percentage strain range where piezo ceramics fail. The harvesting performance of ceramic patches has also been evaluated. Measurements will be conducted on a complex beam shape to confirm the theoretical results as well when the theoretical model is completed. Future development encompasses dynamic coupling since the behaviour may be influenced as more energy is extracted. An iteration algorithm will need to be selected for the optimization process. Lastly electrical models will be included as this directly determines the harvesting efficiency. The final tool will be applicable on any slender structure which exhibits complex harmonic loading

Genetically Engineered iPSC-Derived FTDP-17 MAPT Neurons Display Mutation-Specific Neurodegenerative and Neurodevelopmental Phenotypes

Tauopathies such as frontotemporal dementia (FTD) remain incurable to date, partially due to the lack of translational in vitro disease models. The MAPT gene, encoding the microtubule-associated protein tau, has been shown to play an important role in FTD pathogenesis. Therefore, we used zinc finger nucleases to introduce two MAPT mutations into healthy donor induced pluripotent stem cells (iPSCs). The IVS10+16 mutation increases the expression of 4R tau, while the P301S mutation is pro-aggregant. Whole-transcriptome analysis of MAPT IVS10+16 neurons reveals neuronal subtype differences, reduced neural progenitor proliferation potential, and aberrant WNT/SHH signaling. Notably, these neurodevelopmental phenotypes could be recapitulated in neurons from patients carrying the MAPT IVS10+16 mutation. Moreover, the additional pro-aggregant P301S mutation revealed additional phenotypes, such as an increased calcium burst frequency, reduced lysosomal acidity, tau oligomerization, and neurodegeneration. This series of iPSCs could serve as a platform to unravel a potential link between pathogenic 4R tau and FTD

Power harvesting in a helicopter rotor using a piezo stack in the lag damper

A piezoelectrically augmented helicopter lag damper has been simulated for the purpose of harvesting electrical energy within the rotor of the aircraft. This energy can then be consumed locally for sensing, processing and transmission of data to the cockpit. An 8.15m radius rotor is considered and in-plane rigid lagging motion forms the prime excitation of the damper. The piezoelectric stack is installed within the rod of the damper in such a manner that the stack is submitted to all damper loads. MATLAB and Simulink are used to simulate a simplified blade model. A number of electrical harvesting circuits are investigated and the piezo stack is optimized for each circuit. Also the effect of nonlinear capacitance of the piezo material is investigated revealing a profound effect. Important design parameters are identified and optimized resulting in a power output of 5.1W for a steady 130 knots forward flight profile

BDES3020 'inside' <VanKhanh, Phan>

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Essential role for TRPV1 in stress-induced (mast cell-dependent) colonic hypersensitivity in maternally separated rats

Irritable bowel syndrome is in part characterized by an increased sensitivity to colonic distension. Stress is an important trigger factor for symptom generation. We hypothesized that stress induces visceral hypersensitivity via mast cell degranulation and transient receptor ion channel 1 (TRPV1) modulation. We used the rat model of neonatal maternal separation (MS) to investigate this hypothesis. The visceromotor response to colonic distention was assessed in adult MS and non-handled (NH) rats before and after acute water avoidance (WA) stress. We evaluated the effect of the mast cell stabilizer doxantrazole, neutralizing antiserum against the mast cell mediator nerve growth factor (NGF) and two different TRPV1 antagonists; capsazepine (non-specific) and SB-705498 (TRPV1-specific). Immunohistochemistry was used to assess post-WA TRPV1 expression in dorsal root ganglia and the presence of immunocytes in proximal and distal colon. Retrograde labelled and microdissected dorsal root ganglia sensory neurons were used to evaluate TRPV1 gene transcription. Results showed that acute stress induces colonic hypersensitivity in MS but not in NH rats. Hypersensitivity was prevented by prestress administration of doxantrazole and anti-NGF. Capsazepine inhibited and SB-705498 reversed poststress hypersensitivity. In MS rats, acute stress induced a slight increase in colonic mast cell numbers without further signs of inflammation. Post-WA TRPV1 transcription and expression was not higher in MS than NH rats. In conclusion, the present data on stress-induced visceral hypersensitivity confirm earlier reports on the essential role of mast cells and NGF. Moreover, the results also suggest that TRPV1 modulation (in the absence of overt inflammation) is involved in this response. Thus, mast cells and TRPV1 are potential targets to treat stress-induced visceral hypersensitivit