Output Power Level Research Articles

Effect of Workload and Pedalling Rate on Physiological Response for Male Worker

Until about two and half centuries ago, muscle power was the prime source of energy for performing all the physical activities on our earth, and much of this power had been from human muscles. Because of the socio-economic conditions of farmers in developing countries including India, human muscle power is going to contribute energy requirements for performing many farm activities for the next two decades. Pedalling is the most efficient way of utilising power from human muscles. Pedal power enables a person to drive devices at the same or higher rate as that achieved by hand cranking, but with far less effort and fatigue. However, the use of pedal power for occupational work such as stationary farm operations has got scant attention in the past. Keeping these points into consideration a study was planned for Effect of workload and pedalling rate on physiological response for male worker. Physiological responses of 20 male subjects were studied on a computerised bicycle ergometer at four levels of power output (60, 70, 80, 90 W) four levels of pedalling rates (40, 50, 60, 70 rev/min). Analysis of data indicated that physiological responses were significantly affected with power output as well as pedalling rate. Increases in physiological responses (heart rate and oxygen consumption rate) over rest were significantly higher when pedalling frequency was 50rev/min and above 60rev/min. There was no significant difference between physiological responses at 50 and 60 rev/min. Physiological responses increased linearly with power output and were significantly different at different power outputs. The average value of physiological responses at 60W power output at male agriculture worker at 50rev/min pedalling rate were within acceptable limits for continuous pedalling work.

Analysis of output characteristics of LD end-pumped 2.94 μm continuous-wave Er:YAG laser

Abstract Considering self-saturation effect and thermal effect, a detailed theoretical analysis of the output characteristics of the 2.94 μm continuous-wave (CW) Er:YAG laser with a 10 mm long 50 at.% Er:YAG crystal end-pumped by a 976 nm LD is carried out by solving transient rate equations and heat conduction equations. It is shown that there is a minimum pump power threshold of 0.27 W for the 2.94 μm CW Er:YAG laser. The main factor which limits the significant increase of pump power is the thermal damage risk of the crystal’s pump end-face coating. To minimize the risk, the CW operating temperature of the pump end-face coating is set to be no higher than 200 °C, and therefore the value of the pump beam waist radius is limited to 40 μm ⩽ w 0 ⩽ 490 μm. Within the range, a maximum 2.94 μm CW laser output power of 4.03 W is achieved with a pump beam waist radius of 100 μm. By bonding a 2.5 mm long YAG crystal at the pump-end of the Er:YAG crystal, the CW operating temperature of the pump end-face coating is reduced to the room temperature of 20 °C. Under this condition, the limiting factor for a substantial increase of pump power is the thermal damage risk induced by large interior thermal stress of the Er:YAG crystal. Assuming the interior thermal stress of the CW operating Er:YAG crystal is less than 341 MPa according to the material characteristics, the pump power can be increased by increasing the pump beam waist radius. When the beam waist radius is 430 μm, a maximum 2.94 μm CW laser output power of 38.7 W is obtained. Compared with the unbonded condition, the output power level of the 2.94 μm CW Er:YAG laser is promoted.

Power Sharing of Different Distributed Generator Sets in Microgrid Based on Consensus Control

ABSTRACTMicrogrids incorporate renewable energy sources, battery energy storage systems (BESS), and local loads to operate either with the main grid or independently. In microgrids, virtual synchronous generators (VSGs) and droop control are commonly used to regulate renewable energy sources, providing frequency and voltage control. The VSG and droop control adjust active power based on frequency deviation. However, their effectiveness depends on parameters and does not fully address power‐sharing issues. Traditionally, power sharing is handled by secondary control via the microgrid central controller (MGCC), introducing a centralized, hierarchical approach. To enhance decentralization in microgrids, this paper proposes a consensus based power sharing scheme and its corresponding control for the distributed generators (DGs). The output power levels of DG units are determined by their capacities, ensuring efficient operation. Unlike existing approaches using a hierarchical framework, this work integrates primary and secondary control into a unified distributed control framework. Building on VSG control for microgrid voltage regulation, consensus control is added to manage the distribution of active power. A rigorous theoretical analysis is conducted to validate the proposed method. The method is capable of ensuring active power sharing without relying on an MGCC, and the sharing is also based on the ratio of rated capacities. The controller proposed in this paper achieves the expected control performance, effectively distributing active power sharing in the microgrid. Finally, the effectiveness and performance of the proposed method are verified through comprehensive case studies.

Analysis and Design of Low-Power Piezoelectric Energy Harvesting Circuit for Wearable Battery-Free Power Supply Devices

Improving microelectronic technologies has created various micro-power electronic devices with different practical applications, including wearable electronic modules and systems. Furthermore, the power sources for wearable electronic devices most often work with electrical energy obtained from the environment without using standard batteries. This paper presents the structure and electrical parameters of a circuit configuration realized as a prototype of a low-power AC-DC conversion circuit intended for use as a power supply device for signal processing systems that test various biomedical parameters of the human body. The proposed prototype has to work as a wearable self-powered system that transfers electrical energy obtained through mechanical vibrations in the piezoelectric generator. The obtained electrical energy is used to charge a single low-voltage supercapacitor, which is used as an energy storage element. The proposed circuit configuration is realized with discrete components consisting of a low-voltage bridge rectifier, a low-pass filter, a DC-DC step-down (buck) synchronous converter, a power-controlling system with an error amplifier, and a window detector that produces a “power-good” signal. The power-controlling system allows tuning the output voltage level to around 1.8 V, and the power dissipation for it is less than 0.03 mW. The coefficient of energy efficiency achieved up to 78% for output power levels up to 3.6 mW. Experimental testing was conducted to verify the proposed AC-DC conversion circuit’s effectiveness, as the results confirmed the preliminary theoretical analyses and the derived analytical expressions for the primary electrical parameters.

Comparison of Different Modulation Control Strategies for Wireless Power Transfer System

When designing a wireless power transfer system, overall system efficiency is one of the key parameters. The efficiency depends on several parameters, which also includes control modulation, used for excitation of the transmitter coil. However, how much the modulation technique impacts the efficiency is studied rarely. In this paper, we compare the three most popular control modulation techniques for transmitter voltage of a wireless power transfer system. First, the theory behind the methods is presented by highlighting the difference between them and their implementation. The methods are implemented, together with a linear PI control scheme, to evaluate the efficiency and performance of each of the methods. Finally, the practical tests were performed, under different output power levels, in order to evaluate the practical performance of each modulation strategy further.

Introducing Silencers on Micro Turboshafts Powering Unmanned Aerial Vehicles

The transition to alternative electrical energy solutions for drone propulsion systems presents several challenges, particularly in managing noise. This noise, compounded by that from the propellers, can produce spectra that are either unpleasant to humans or detrimental to mission objectives. This study explores potential solutions to mitigate noise produced by a micro turboshaft engine, focusing on the solutions’ impact on weight, power output, and acoustic level. We propose two modular, scalable designs—one for the intake and one for the exhaust—based on well-known applications in cold and hot flows. These designs aim to operate effectively across the audible frequency spectrum and incorporate various Helmholtz resonator geometries, including combinations of different lengths, perforated metal sheet parameters, and cavity-filling materials, to enhance bandwidth and noise reduction. Experimental results indicate that these designs can achieve tonal noise reductions of up to 40 dB. While the results are promising, further analysis is required to evaluate the practical applicability and comprehensive impact of these solutions on drone performance.

Разработка усилителя со скрещенными полями W-диапазона

The results of the development of a W-band crossed-field amplifier are presented. The optimal geometry of the slow-wave system was determined and its dispersion characteristics were calculated. Three-dimensional modeling using the large-particle method is performed, which demonstrates a gain of up to 15 dB and a maximum output power level of more than 1 kW.

Smith Chart-Based Design of High-Frequency Broadband Power Amplifiers

This paper presents a comprehensive study on the design and performance of a high-power amplifier (PA) covering a broad frequency band from 0.1 to 4.8 GHz. Leveraging a 10 W GaN device, the amplifier achieves output power levels surpassing 10 W across the entire frequency band. Furthermore, the power-added efficiency (PAE) of the amplifier ranges from 47% to 59%, indicating its energy-efficient operation. With consistent gain characteristics varying between 7 and 15 dB, the design ensures reliable signal amplification for diverse applications. Notably, the approach introduces a simplified output matching network based on an LC network, prioritizing practicality without sacrificing performance. Additionally, comprehensive guidance is provided on utilizing the Smith chart for streamlined amplifier design, enabling engineers with an accessible methodology. Through a meticulous analysis, this work contributes to advancing the field of high-power amplification, offering enhanced performance and usability for next-generation wireless communication systems.

Study on the Performance of a Novel Double-Section Full-Open Absorption Heat Pump for Flue Gas Waste Heat Recovery

Open absorption heat pumps are considered one of the most promising methods for efficiently utilizing low-grade waste heat, reducing energy consumption, and lowering greenhouse gas emissions. However, traditional heat pumps have significant limitations in the range of flue gas temperatures they can recover, and their relatively low system performance further restricts practical applications. In this study, we propose a novel double-section full-open absorption heat pump driven by flue gas from the desulfurization tower. By designing the absorber with a double-layer structure, the system can recover more latent and sensible heat from the flue gas, significantly enhancing its thermal recovery capability. Additionally, replacing the traditional LiBr/H2O working pair with LiCl/H2O significantly reduces the risks of solution crystallization and equipment corrosion. Through comprehensive research, the strengths and weaknesses of the system were explored. The results indicate that this system effectively recovers flue gas waste heat within the temperature range of 30–70 °C. Specifically, at a flue gas temperature of 70 °C and a flow rate of 3 kg/s, the system achieves a COP of 1.838, along with a heating capacity of 158.83 kW and a ROI of 34.1%. These metrics demonstrate that the system not only delivers high performance but also exhibits excellent economic viability. Additionally, when the solution temperature is lowered to 10 °C, the system’s maximum COP reaches 1.96, reflecting a significant 30.67% improvement over traditional heat pumps. These findings highlight the system’s potential for application in coal-fired power plants, where varying levels of power output can benefit from enhanced thermal recovery and efficiency.

Class iCGF–1 Mode Power Amplifier for Enhancing the Linearity of the Traditional Continuous Class F–1 Mode

ABSTRACTIn this paper, the iCGF−1 mode is proposed to compensate the amplitude‐to‐amplitude modulation (AM/AM) distortion of the traditional continuous class F−1 mode while maintaining the high efficiency. The AM/AM profile of the iCGF−1 mode is mathematically expressed simultaneously as a function of the input nonlinearity parameter and conduction angle , which makes the iCGF−1 mode more flexible in controlling the AM/AM profile. The first inflection point of the AM/AM profile can be moved to a higher output power level through theoretical deduction by adjusting the second harmonic source impedance and gate bias voltage to increase the values of and . This flattens the AM/AM profile while the efficiency profile remains almost the same as that of the traditional continuous class F−1 mode. The performance of the iCGF−1 mode is verified through simulation and experimental measurements. The iCGF−1 PA is fabricated with CGH40010F and has a frequency range of 2–2.6 GHz. The drain efficiency is 70.1%–77.9%, and the output power is 41.1–41.7 dBm. The linearity is tested with a 100 MHz 5G NR signal (the peak average power ratio (PAPR) is 8.5 dB) at 2.3 GHz. The worst adjacent channel power ratio (ACPR) is −32.3 dBc without digital predistortion (DPD) and −52.1 dBc with DPD. The results show that the iCGF−1 mode has successfully compensated the AM/AM distortion of the traditional continuous class F mode and maintaining high efficiency.

Transducer module apodization to reduce bone heating during focused ultrasound uterine fibroid ablation with phased arrays: A numerical study.

During magnetic resonance-guided focused ultrasound (MRgFUS) surgery for uterine fibroids, ablation of fibrous tissues in proximity to the hips and spine is challenging due to heating within the bone that can cause patients to experience pain and potentially damage nerves. This far-field bone heating limits the volume of fibroid tissue that is treatable viaMRgFUS. To investigate transducer module apodization for improving the ratio of focal-to-bone heating ( ) when targeting fibroid tissue close to the hips and spine, to enable MRgFUS treatments closer to thebone. Acoustic and thermal simulations were performed using 3D magnetic resonance imaging (MRI)-derived anatomies of ten patients who underwent MRgFUS ablation for uterine fibroids using a low-frequency ( ) 6144-element flat fully-populated modular phased array system (Arrayus Technologies Inc., Burlington, Canada) at our institution as part of a larger clinical trial (NCT03323905). Transducer modules ( per module) whose beams intersected with no-pass zones delineated within the field were identified, their output power levels were reduced by varying blocking percentage levels, and the resulting temperature field distributions were evaluated across multiple sonications near the hip and spine bones in each patient. Acoustic and thermal simulations took approximately ( ) and ( ) to run for a single near-spine (near-hip) target,respectively. For all simulated sonications, transducer module blocking improved compared to the no blocking case. In just over half of sonications, full module blocking maximized (increase of 82% 38% in 50% of hip targets and 49% 30% in 62% of spine targets vs. no blocking; mean±SD), at the cost of more diffuse focusing (focal heating volumes increased by 13%±13% for hip targets and 39%±27% for spine targets) and thus requiring elevated total (hip: 6%±17%, spine: 37%±17%) and peak module-wise (hip: 65%±36%, spine: 101%±56%) acoustic power levels to achieve equivalent focal heating as the no blocking control case. In the remaining sonications, partial module blocking provided further improvements in both (increased by 29%±25% in the hip and 15%±12% in the spine) and focal heating volume (decrease of 20%±10% in the hip and 34%±17% in the spine) relative to the full blocking case. The optimal blocking percentage value was dependent on the specific patient geometry and target location of interest. Although not all individual target locations saw the benefit, element-wise phase aberration corrections improved the average compared to the no correction case (increase of 52%±47% in the hip, 35%±24% in the spine) and impacted the optimal blocking percentage value. Transducer module blocking enabled ablative treatments to be carried out closer to both hip and spine without overheating or damaging the bone (no blocking: / , full blocking: / , optimal partial blocking: / for hip/spine). The proposed transducer apodization scheme shows promise for improving MRgFUS treatments of uterine fibroids, and may ultimately increase the effective treatment envelope of MRgFUS surgery in the body by enabling tissue ablation closer to bonystructures.

Numerical Analysis of Hydrogen-Enriched Natural Gas on Combustion and Emission Characteristics

AbstractThe integration of hydrogen into natural gas infrastructure presents a viable strategy for mitigating greenhouse gas emissions and advancing toward carbon neutrality. This study investigates the combustion characteristics and emissions profiles of hydrogen-enriched natural gas mixtures, specifically focusing on the composition of Russian pipeline natural gas. A comprehensive mathematical model was developed to predict emission concentrations and simulate fuel mixture combustion using MATLAB Simulink software. This versatile model facilitates further analysis within the MATLAB ecosystem. The simulation results demonstrate a significant correlation between the hydrogen content in the natural gas mixture and the resulting heat power output. With a constant fuel consumption rate, a notable decrease in heat power was observed as the hydrogen concentration increased, reaching a maximum reduction of 44.9% at a 45% hydrogen content. These findings underscore the feasibility of partially substituting natural gas with hydrogen, while also highlighting the necessity for increased fuel flow rates to maintain equivalent power output levels. This poses additional challenges for natural gas grid operators, necessitating infrastructure adaptations to accommodate higher fuel demands. The insights gained from this research contribute to the growing body of knowledge surrounding hydrogen integration in the energy sector, offering valuable implications for decarbonization strategies and the optimization of natural gas infrastructure.

The Ex-Timing trial: evaluating morning, afternoon, and evening exercise on the circadian clock in individuals with type 2 diabetes and overweight/obesity—a randomized crossover study protocol

BackgroundExercise is known to provide multiple metabolic benefits such as improved insulin sensitivity and glucose control in individuals with type 2 diabetes mellitus (T2DM) and those at risk. Beyond the traditional exercise dose, exercise timing is perceived as a contemporary hot topic, especially in the field of T2DM; however, the number of intervention studies assessing exercise timing and glucose metabolism is scarce. Our aim is to test the effect of exercise timing (i.e., morning, afternoon, or evening) on the inter-individual response variability in glycemic control and related metabolic health parameters in individuals with T2DM and those at risk during a 12-week intervention.MethodsA randomized crossover exercise intervention will be conducted involving two groups: group 1, individuals with T2DM; group 2, age-matched older adults with overweight/obesity. The intervention will consist of three 2-week blocks of supervised post-prandial exercise using high-intensity interval training (HIIT). Between each training block, a 2-week washout period, where participants avoid structured exercise, will take place. Assessments will be conducted in both groups before and after each exercise block. The primary outcomes include the 24-h area under the curve continuous glucose monitoring-based glucose. The secondary outcomes include body composition, resting energy expenditure, insulin response to a meal tolerance test, maximal aerobic capacity, peak power output, physical activity, sleep quality, and insulin and glucose levels. All primary and secondary outcomes will be measured at each assessment point.DiscussionOutcomes from this trial will provide us additional insight into the role of exercise timing on the inter-individual response variability in glycemic control and other related metabolic parameters in two distinct populations, thus contributing to the development of more effective exercise prescription guidelines for individuals with T2DM and those at risk.Trial registrationClinicalTrials.gov NCT06136013. Registered on November 18, 2023.

Features of building millimeter-wave power combiners with an increased output power level

The problems of designing output power amplifiers of radio transmitting systems based on the summation of the power of individual monolithic integrated circuits are considered. An analysis of well-known solutions for the construction of multichannel power summation devices in the millimeter wave range is carried out. On its basis, proposals have been developed for the construction of multi-channel summation devices with an increased level of output power. The developed devices make it possible to increase the density of amplifier cells and the level of output power while maintaining the permissible thermal regime. Individual amplifier cells can also be replaced. The developed recommendations for the construction of multi-channel millimeter-wave power summation devices can be used in the creation and improvement of output power amplifiers of radio transmitting systems.

Response surface methodology optimization of characteristics of biodiesel powered diesel engine and its effective integration to autonomous microgrid

An optimum diesel engine load condition with higher thermal efficiency and energy management has been the foremost challenge in the renewable energy research field. Modern trends involve nano additives for obtaining high performing biodiesel blends. Considering the above-mentioned factors, an experimental study along with statistical analysis has been performed with variation of compression ratio (16, 17.5 & 18), ZrO2 nano additive (50, 100 & 150 ppm) and load (50, 75 & 100 %). The optimization was accomplished by diminishing the BSFC, NOx, HC, CO, and increasing the BTE, CO2 using the approach of desirability. From the obtained results, the optimum operating conditions of the engine were found to be 75 % load, 18:1 compression ratio, and 150 ppm ZrO2 nano additive. The actual values at optimized conditions are obtained as BSFC (0.27 kg/kWh), BTE (33.37 %), CO (0.71 %), CO2 (8.69 %), NOx (1270 ppm), HC (62 %) and Smoke (25.20 %) with error less than 5 %. It has been observed that the BSFC of the proposed biodiesel-diesel blend is lower than that of pure diesel in all levels of power output. The biodiesel fuelled diesel engine is integrated as backup power in autonomous microgrid with main power as solar PV system operated at MPPT mode. A hybrid power system based on solar PV and biodiesel generator set up is the better alternative to emission-intensive fossil fuel and intermittent renewable.

Deep Learning-based Intelligent Fault Diagnosis for Power Distribution Networks

Power distribution networks with distributed generation (DG) face challenges in fault diagnosis due to the high uncertainty, randomness, and complexity introduced by DG integration. This study proposes a two-stage approach for fault location and identification in distribution networks with DG. First, an improved bald eagle search algorithm combined with the Dijkstra algorithm (D-IBES) is developed for fault location. Second, a fusion deep residual shrinkage network (FDRSN) is integrated with IBES and support vector machine (SVM) to form the FDRSN-IBS-SVM model for fault identification. Experimental results showed that the D-IBES algorithm achieved a CPU loss rate of 0.54% and an average time consumption of 1.70 seconds in complex scenarios, outperforming the original IBES algorithm. The FDRSN-IBS-SVM model attained high fault identification accuracy (99.05% and 98.54%) under different DG output power levels and maintained robustness (97.89% accuracy and 97.54% recall) under 5% Gaussian white noise. The proposed approach demonstrates superior performance compared to existing methods and provides a promising solution for intelligent fault diagnosis in modern distribution networks.

Effects of mild hypercapnia on myocardial injury after out-of-hospital cardiac arrest. A sub-study of the TAME trial

PurposeMild hypercapnia did not improve neurological outcomes for resuscitated out-of-hospital cardiac arrest (OHCA) patients in the Targeted Therapeutic Mild Hypercapnia After Resuscitated Cardiac Arrest (TAME) trial. However, the effects of hypercapnic acidosis on myocardial injury in patients with cardiac arrest is unexplored.We investigated whether mild hypercapnia compared to normocapnia, following emergency coronary intervention, increased myocardial injury in comatose OHCA-patients with AMI. MethodsSingle-centre, prospective, pre-planned sub-study of the TAME trial. Patients were randomised to targeted mild hypercapnia (PaCO2 = 6.7–7.3 kPa) or normocapnia (PaCO2 = 4.7–6.0 kPa) for 24 h. Myocardial injury was assessed with high-sensitive cardiac troponin T (hs-cTnT) measured at baseline, 24, 48 and 72 h. Haemodynamics were assessed with right heart catheterisation and blood-gas analyses every 4th hour for 48 h. ResultsWe included 125 OHCA-patients. 57 (46%) had an AMI, with 31 and 26 patients randomised to hypercapnia and normocapnia, respectively. Median peak hs-cTnT in AMI-patients was 58% lower in the hypercapnia-group: 2136 (IQR: 861–4462) versus 5165 ng/L (IQR: 2773–7519), p = 0.007. Lower average area under the hs-cTnT curve was observed in the hypercapnia-group: 2353 (95% CI 1388–3319) versus 4953 ng/L (95% CI 3566–6341), P-group = 0.002. Hypercapnia was associated with increased cardiac power output (CPO) and lower lactate levels in patients with AMI (P-group < 0.05). hs-cTnT, lactate and CPO were not significantly different between intervention groups in OHCA-patients without AMI (p > 0.05). ConclusionsMild hypercapnia was not associated with increased myocardial injury in resuscitated OHCA-patients. In AMI-patients, mild hypercapnia was associated with lower hs-cTnT and lactate, and improved cardiac performance.Trial registration number: NCT03114033.

Multi objectives optimization of wind turbines’ power and fatigue loads using perturbation free extremum seeking control

This manuscript introduces a perturbation-free extremum-seeking control strategy specifically designed to enhance the operational performance of wind turbines under optimal conditions. The strategy employed utilizes a perturbation-free extremum-seeking approach to ensure the wind turbine farm operates at maximum power efficiency while also reducing power output fluctuations. By employing this control system, the wind turbine generators are maintained at their optimal power output level, effectively navigating through disturbances such as tower shadow, wind shear, and the erratic nature of wind speeds without introducing external perturbations.The algorithm is adept at managing the blade pitch angles and the turbines’ rotational speed, ensuring a controlled and efficient operation. Furthermore, this paper outlines a perturbation-free method to optimize energy production and decrease fatigue loads, thereby extending the operational lifespan of a wind turbine. The superior operational efficiency of the wind turbine array generators achieved through this approach underscores its effectiveness.The robustness and effectiveness of this perturbation-free control system are validated through comprehensive simulation tests on an array comprising four wind turbine generators. The outcomes of these simulations solidly back the extremum-seeking control system’s proficiency in reaching maximum power output without relying on perturbative methods, highlighting its innovative contribution to wind turbine efficiency optimization.

Research on Hybrid Vibration Sensor for Measuring Downhole Drilling Tool Vibrational Frequencies

The vibration parameters during drilling play a critical role in enhancing drilling speed and ensuring safety. However, traditional downhole vibration sensors face limitations in their power supply methods, hindering widespread adoption. To address this challenge, our research introduces a novel solution: a hybrid downhole vibration sensor (HDV-TENG) utilizing triboelectric nanogenerators. This sensor not only enables the measurement of low- to medium–high-frequency vibrations using self-power but also serves to energize other downhole devices. We utilized a self-constructed vibration simulator to replicate downhole drilling tool vibrations and conducted a comprehensive series of sensor tests. The test results indicate that the frequency measurement bandwidth of the HDV-TENG spans from 0 to 200 kHz. Especially, the measurement errors for vibrations within the low-frequency range of 0 to 10 Hz and the high-frequency range of 10 to 200 k Hz are less than 5% and 8%, respectively. Additionally, the experimental findings regarding load matching demonstrate that the HDV-TENG achieves an output power level in the milliwatt range, representing a significant improvement over the output power of traditional triboelectric nanogenerators. Unlike traditional downhole vibration measurement sensors, HDV-TENG operates without requiring any external power supply, thereby conserving downhole space and significantly enhancing drilling efficiency. Furthermore, HDV-TENG not only offers a broad measurement range but also amplifies output power through the synergy of a triboelectric nanogenerator (TENG), piezoelectric nanogenerator (PENG), and electromagnetic power generator (EMG). This capability enables its utilization as an emergency power source for other micropower equipment downhole. The introduction of HDV-TENG also holds considerable implications for the development of self-powered underground sensors with high-frequency measurement capabilities.

Optimal performance and preliminary parameter matching for hydrogen fuel cell powertrain system of electric aircraft

Fuel cells are true net-zero carbon emission power sources for aircraft, which is highly sensitive to weight. In the initial phase of adapting hydrogen fuel cell systems for aircraft powertrains, preliminary design parameter matching remains premature. An explicit method for the performance optimization of aircraft hydrogen fuel cell powertrain systems and a process of preliminary parameter matching are proposed to address this problem. Performance and weight models of the fuel cell stack and its auxiliaries, the cathode air compressor subsystem, and the cooling subsystem are designed, and system performance at various altitudes and power output levels is calculated. The aircraft flight mission performance is synthesized and considered in the optimization process. The optimization result of system performance and the corresponding design parameters are then graphically illustrated as tern plots. Unlike the traditional iterative preliminary system parameter matching and optimization method, which explores the design space non-directionally and converges to a single local optimal point, the proposed explicit method sweeps the design space globally and obtains a group of design points with acceptable optimality. The system design process is boosted by a compact iterative loop. In the optimization practice, the cruise powertrain specific energy is improved by 6.5%. The relationship between specific system design parameters and system performance is displayed globally by the resulting tern plots. Multiple design guidelines are observed and proposed, and design scenarios are directly obtained from the graphs for further engineering processes.