Search Results (80)

Under severe flight conditions such as high Mach number and large angle of attack, the aerodynamic environment of guided rockets exhibits highly nonlinear and strongly coupled characteristics. Significant dynamic coupling effects exist among the pitch, yaw, and roll channels, and aerodynamic parameters are subject to considerable uncertainties due to shocks, flow separation, and other factors. These issues collectively pose serious challenges to traditional control design methods based on linearized models. To address these challenges, this paper proposes a variable-gain adaptive decoupling control method. First, based on the classical feedforward decoupling concept, a decoupling controller is designed to preliminarily suppress inter-channel coupling effects. To further cope with aerodynamic parameter perturbations and model uncertainties, a model reference adaptive control framework is introduced, and an online parameter compensation mechanism is constructed to adjust controller parameters in real time according to changes in the aerodynamic environment. Additionally, by defining and estimating a system coupling degree in real time, a variable-gain adaptive law based on coupling degree is designed. This allows the decoupling effort to be dynamically adjusted according to the coupling degree, ensuring effective decoupling while avoiding performance degradation due to over-compensation. Simulation experiments conducted under typical high-dynamic flight scenarios demonstrate that, compared to traditional methods, the proposed approach effectively suppresses inter-channel coupling disturbances and significantly enhances system stability and robustness under parameter uncertainties and external disturbances. This provides a feasible technical solution for controlling guided rockets under extreme aerodynamic conditions. Full article

Pitch control is the standard approach to regulating the rotational speed of large wind energy systems when the wind speed goes over its rated value. However, the pitch control system can also be used to reduce blade loads. In this last case, it is necessary to extend the classic collective pitch control system by including a complicated mechanism, which involves a Coleman or a Clarke transformation. This extension is known as the individual pitch control (IPC). While the performance of the IPC is satisfactory regarding the load alleviation, its dynamics remain insufficiently comprehended, especially due to the previously mentioned embedded transformations. Hence, the tuning of the IPC is sometimes challenging, and the controller can exhibit unexpected behaviours. The idea of this work is to formulate the IPC as a multivariable controller in the input/output representation such that the classic tools for the analysis and control of linear systems can be applied. As a result, some lesser-known properties as well as limitations are disclosed. Specifically, the approach makes apparent the existence of proportional-resonant controllers, which are crucial for dynamical behaviour. This additional knowledge can assist in the design of control systems and the tuning of controllers. A simulation study completes the presentation, including qualitative and quantitative analysis. Full article

Background/Objectives: The goal of the study was to identify the peculiarities of attention deficit hyperactivity disorder (ADHD) on the base of the behavioral characteristics and acoustic features of speech of children with ADHD and ADHD with comorbidity—ADHD and autism spectrum disorders (ASD) and ADHD and intellectual disabilities (ID)—within the framework of one test task. Behavioral characteristics were selected using DSM-V criteria; acoustic features of speech were considered by researchers as speech markers of ASD and ID detected for different languages. Methods: The study includes 92 children aged 5–13 years with ADHD, ADHD and ID, ADHD and ASD, and control groups of children diagnosed with ASD, ID and typically developing (TD) children. The children were tested using the test task “co-op play”. Video and audio recordings of children performing the test task were collected. We used a complex approach to study the peculiarities of children with ADHD through expert analysis of children’s behavior and play, acoustic spectrographic analysis of speech and questionnaires about early childhood development filled out by parents. Results: The characteristics of behavior, play, and acoustic features of speech of children with ADHD and ADHD and comorbidity were revealed. Children with ADHD had lower behavior scores in the play situation on the expert assessment than TD children, with the greatest differences for characteristics of play, “Playing for toy”, and of behavior “Displaced activity” and “Losing attention”. The speech of children with ADHD is characterized by low values of the third formant and the difference between the first two formants, compared to the corresponding speech features of children from other groups. The speech of children with ADHD+ASD is characterized by maximal pitch values (high voice), while that of children with ADHD+ID is characterized by low vowel articulation index values. Conclusions: Based on the analysis of behavior and speech of children with TD, ADHD, ADHD and comorbidity performing the “co-op play” test task, the set of characteristics specific to ADHD was identified. The obtained data expand our understanding of the specificity of children with ADHD and may contribute to the development of qualified support for families with children with ADHD. Full article

Under extreme fault conditions or during maintenance restarts, DC collection wind farms may experience a total blackout due to protective isolation. Addressing the black-start challenges arising from the unidirectional power flow structure and weak damping characteristics inherent to DC step-up collection wind farms, this paper proposes a sequential black-start control scheme predicated on grid-source coordination. A representative topology and an equivalent black-start model of the DC collection system are established to analyze the start-up mechanism and to design an active voltage build-up strategy with virtual impedance for the grid-side Modular Multilevel Converter (MMC). Meanwhile, generator-side permanent-magnet direct-drive wind turbines exploit their self-excitation capability and optimized pitch control to realize islanded self-bootstrapping and stable rotational speed. In addition, we develop a two-stage soft cut-in strategy that combines open-loop voltage scanning for pre-synchronization with closed-loop constant-current ramping of DC/DC converters, together with control logic for sequentially connecting multiple units to the DC grid. Simulation results show that the proposed approach smoothly restores the system from a zero-energy state to the rated operating point without external power sources, confirming the feasibility of full-farm start-up using the grid-side converter station and unit self-bootstrapping. Full article

Certified flight simulation training devices support pilot training and standardized instruction. However, high acquisition costs and vendor constraints on high-resolution operational/flight data can hinder academic research. This paper describes a low-cost, academically accessible simulator research infrastructure for systematic flight data logging, traceability, and post-flight visualization/analysis. The platform combines a two-station architecture (pilot and instructor) with a modular cockpit layout and physical interfaces (control column, rudder pedals, and switch panels), visual/auditory feedback, and software for scenario management and monitoring. A key contribution is a high-resolution (≥60 Hz) end-to-end data logging and traceability workflow that captures relevant telemetry, stores it in purpose-oriented formats (replay, .csv/.xlsx for analysis, and .log for maintenance), and enables time-aligned debriefing via the IOS/Pilot Log. As a proof of concept, a single-sample illustrative demonstration uses landing-phase data to generate representative diagnostic plots (approach profile, pitch–roll behavior, heading–track relationships), demonstrating the types of post-flight diagnostic visualizations that the infrastructure can generate. Since no baseline/control conditions, repeated trials, or benchmarks are included, the demonstration does not support generalized performance claims. Overall, the system is designed to provide an experimental infrastructure for researchers seeking to collect and analyze flight data using a simulator. Full article

The advent of electric propulsion for new aircraft designs necessitates the optimization of propeller aerodynamic performance and the reduction of acoustic signatures. Variable-pitch propellers present a promising solution, offering the flexibility to adjust blade angles in response to different flight conditions. The study investigates the performance of blade pitch configurations tailored to specific flight conditions. Rather than a dynamic pitch change, the research evaluates discrete pitch settings coupled with corresponding advance ratios to identify optimal operating points. Findings show that increasing collective pitch in response to a higher advance ratio (forward flight) successfully maintains aerodynamic efficiency and thrust, with an expected increase in torque. While this adjustment leads to an anticipated rise in noise due to higher aerodynamic loading, results reveal that a collective pitch increment of $+5°$ actively suppresses broadband noise at frequencies above 2 kHz. Analysis of the flow field and surface pressure fluctuations indicates this suppression is directly attributed to the mitigation of outboard propeller stall. Ultimately, this work demonstrates the feasibility of using collective pitch adjustments not only to enhance flight performance but also to actively control and suppress components of the propeller noise signature, such as the broadband noise. Full article

This paper addresses Region-3 control of a 2.5 MW three-bladed HAWT using a data-driven workflow that links empirical modeling to implementable pitch control. To focus on fundamental regulation dynamics, the turbine is modeled as a rigid single-mass drivetrain driven by identified quasi-steady aerodynamics. First, we identify a compact shaft-power surface $P(\omega ,V,\beta )$ and recover the associated MPP condition, which clarifies why the optimal rotor speed rises with wind and motivates a comparison between capped-MPP operation and constant-speed regulation. We then synthesize a practical Region-3 loop—PI in rate with a first-order pitch servo and saturation handling—and evaluate proportional (P), PI, and PI + servo controllers under sinusoidal and Kaimal-turbulent inflow. Finally, we propose an adaptive PI variant that keeps a fixed acceleration feed-through but retunes the integral path online via ARX(1,1) + RLS to maintain a target closed-loop bandwidth. Performance metrics computed over the full simulation window (t ∈ [0, 50] s) show that P-only control exhibits large steady bias and cap violations; PI recenters speed and power around their targets; adding a pitch servo further trims peaks and ripple. In steady-state turbulent tests, PI + servo achieves tight regulation, Δω_peak ≈ 0.033% (0.079 rad/s), P_RMS ≈ 0.62%, while the adaptive PI maintains similar tightness with the lowest variability overall Δω_peak ≈ 0.0104% (0.025 rad/s), P_RMS ≈ 0.17. The workflow yields a practically implementable β(V) schedule and a lightweight adaptation mechanism that compensates for slow aerodynamic performance drift without changing the control structure. While structural loads and aeroelastic modes are not explicitly modeled, the proposed controller enforces strict speed and power constraints via a rigid-body dynamic analysis. Extensions to IPC, preview/forecast augmentation, and validation on higher-fidelity aeroelastic/drivetrain models are identified as future work. Full article

The construction of ultra-high voltage transmission lines puts extremely high demands on the high-altitude operation of heavy-load unmanned aerial vehicles (UAV). Air density and temperature at high altitudes have a great influence on the efficiency and stability of the UAV power system. Traditional regulation methods based on parameters pre-set or simple look-up tables cannot achieve the best adaptability. In this paper, we presents an intelligent method for the high-altitude adaptability control of heavy-load UAV power systems using a deep neural network. The proposed method collects real-time, multi-dimensional environmental parameters, including altitude, temperature, and air pressure, using a barometric altimeter and GPS receiver, constructs a High-Altitude Adaptive Regulation Network (HAARN), and intelligently learns complex nonlinear relationships to predict the optimal motor speed, propeller pitch angle, and current limit under the current environmental conditions so as to dynamically adjust power output. The HAARN model was trained on a dataset of 12,000 synchronized samples collected from both controlled environmental-chamber experiments (temperature range: −10 $°\mathrm{C}$ to 20 $°\mathrm{C}$; pressure range: 100–50 kPa, corresponding approximately to 0–5500 m) and multi-point plateau flight trials conducted at 2000 m, 3000 m, 4000 m, and 4500 m. This combined dataset was used for feature engineering, exhaustive-label generation, and model validation to ensure robust generalization across realistic high-altitude operating conditions. Experimental results show that, compared with traditional PID control and lookup-table approaches, the proposed method reduces thrust attenuation by about 12.5% and improves energy efficiency by 8.3% at the altitude of 4000 m. In addition, HAARN demonstrates consistent improvements across the tested altitude range (0–4500 m). Full article

Low-melting bioabsorbable polymers, such as poly(caprolactone-co-lactide) (PCLA), hold significant promise for biomedical applications. However, achieving high-precision micro- and nanotopographical functionalization remains a formidable challenge due to the material’s susceptibility to thermal deformation during conventional thermal molding processes. In this study, functional microstructured PCLA coatings were engineered via low-temperature nanoimprint lithography utilizing a TiO₂–SiO₂ gas-permeable mold. These molds were synthesized via a sol–gel method utilizing titanium dioxide and silicon precursors. The gas-permeable nature of the mold facilitated the efficient evacuation of trapped air and volatiles during the imprinting process, enabling the high-fidelity replication of microstructures (1.3 μm height, 3 μm pitch) and nanostructured PCLA coatings featuring linewidths as narrow as 600 nm. The resultant microstructured PCLA coatings demonstrated modulated surface wettability, evidenced by an increase in water contact angles from 70.1° to 91.4°, and exhibited enhanced FD4 elution kinetics. These results confirm morphology-driven functionalities, specifically hydrophobicity and controlled release capabilities. Collectively, these findings underscore the efficacy of this microfabrication approach for polycaprolactone-based materials and highlight its potential to catalyze the development of high-value-added biomaterials for advanced medical and life science applications. This study establishes a foundational framework for the practical deployment of next-generation bioabsorbable materials and is anticipated to drive innovation in precision medical manufacturing. Full article

Humanoid robots have gained public awareness and intrigue over the last few years. During this time, there has been a greater push to develop robots to behave more like humans, not just in how they speak but also in how they move. A novel humanoid robotic head-and-neck platform designed to facilitate the investigation of movement characteristics is proposed. The research presented here aims to characterise the motion of a humanoid robotic head, Aquila, to aid the development of humanoid robots with head movements more similar to those of humans. This platform also aims to promote further studies in human head motion. This paper proposes a design for a humanoid robotic head platform capable of performing three principal human motion patterns: yaw, pitch, and roll. Using the Arduino IDE (2.3.2) and MATLAB/Simulink (2024b), all three types of movement were implemented and tested with various parameters. Each type of movement is quantified in terms of range, stability, and dynamic response using time-series data collected over 35 s of continuous observation. The results demonstrate that a humanoid robot head can mimic the range of displacement of a healthy human subject but does not exhibit the same smoothness and micro-adjustments observed in dynamic human head movements. An RMSE of under 0.3 rad is achieved for each motion axis—pitch, roll, and yaw—when comparing robotic head movement to human head movement. The investigation of preliminary results highlights the need for further system optimisation. This paper’s conclusion highlights that the bio-inspired control concept, paired with the proposed 8-stepper motor platform, enhances realism and interaction in the context of head movement in robotic systems. Full article

Substantial improvements in the performance of optical interconnects based on multi-mode fibers are required to support emerging single-channel data transmission rates of 200 Gb/s and 400 Gb/s. Future optical components must combine very high modulation bandwidths—supporting signaling at 100 Gbaud and 200 Gbaud—with reduced spectral width to mitigate chromatic-dispersion-induced pulse broadening and increased brightness to further restrict flux-confining area in multi-mode fibers and thereby increase the effective modal bandwidth (EMB). A particularly promising route to improved performance within standard oxide-confined VCSEL technology is the introduction of multiple isolated or optically coupled oxide-confined apertures, which we refer to collectively as multi-aperture (MA) VCSEL arrays. We show that properly designed MA VCSELs exhibit narrow emission spectra, narrow far-field profiles and extended intrinsic modulation bandwidths, enabling longer-reach data transmission over both multi-mode (MMF) and single-mode fibers (SMF). One approach uses optically isolated apertures with lateral dimensions of approximately 2–3 µm arranged with a pitch of 10–12 µm or less. Such devices demonstrate relaxation oscillation frequencies of around 30 GHz in continuous-wave operation and intrinsic modulation bandwidths approaching 50 GHz. Compared with a conventional single-aperture VCSELs of equivalent oxide-confined area, MA designs can reduce the spectral width (root mean square values < 0.15 nm), lower series resistance (≈50 Ω) and limit junction overheating through more efficient multi-spot heat dissipation at the same total current. As each aperture lases in a single transverse mode, these devices exhibit narrow far-field patterns. In combination with well-defined spacing between emitting spots, they permit tailored restricted launch conditions in MMFs, enhancing effective modal bandwidth. In another MA approach, the apertures are optically coupled such that self-injection locking (SIL) leads to lasing in a single supermode. One may regard one of the supermodes as acting as a master mode controlling the other one. Streak-camera studies reveal post-pulse oscillations in the SIL regime at frequencies up to 100 GHz. MA VCSELs enable a favorable combination of wavelength chirp and chromatic dispersion, extending transmission distances over MMFs beyond those expected for zero-chirp sources and supporting transfer bandwidths up to 60 GHz over kilometer-length SMF links. Full article

Tiltrotor aircraft, due to their vertical takeoff and landing capability and efficient high-speed cruise performance, are increasingly valuable in both modern military and civilian applications. However, traditional calibration methods for blade pitch control often lack the precision required for large actuator strokes, which limits the control accuracy. This study aims to overcome these limitations by introducing an improved polynomial fitting algorithm to model the nonlinear relationship between the blade pitch control angles and actuator strokes. Using a specific rotor model, a coordinate system was established for the pitch control mechanism and spatial geometric relationships were derived. Experimental comparisons demonstrate that the proposed cubic polynomial fitting algorithm reduces the collective pitch error by approximately 57% and cyclic pitch error by 33%, markedly outperforming traditional linear fitting methods. These improvements significantly enhance the control precision and operational stability. The findings provide a reliable theoretical and practical basis for improving tiltrotor flight performance and safety. Full article

Water injection development represents the predominant development method for enhancing oil recovery (EOR) efficiency and achieving the balanced utilization of oil reservoirs. In light of the current situation of oilfield water injection technology, a comprehensive overview of the evolution of full-scale water injection technology is given, with particular emphasis on the influence of geological factors, technological advancements, and existing challenges. The principal issues currently encountered include an unequal distribution of layers, the complexity of subdivision, casing deformation, and damage to deep well equipment, which collectively impede the effective implementation of subdivision water injection development technology. The novelty of the research lies in the current development status of full-scale injection wells, which is not only reflected in the depth-scale, but also in the operational difficulty-scale. A thorough exploration of subdivision water injection development technologies has been conducted, and the applicability and limitations of these technologies in diverse reservoir conditions have been evaluated. The proposal is for intelligent injection technology to be adopted for medium–shallow heterogeneous wells, and for ball-pitching plugging profile control technology to be adopted for deep/horizontal/special condition wells. A comparative analysis was conducted to evaluate the characteristics, application scenarios, advantages, and disadvantages of intelligent injection technologies, demonstrating its intelligence, automation, and precision in the practical application. In regard to the ball-pitching plugging profile control technology, the design and performance of the plugging ball, the plugging mechanism, and the application effect were elucidated. Based on the existing challenges in the realm of water injection development, the research prospects for full-scale subdivision water injection development technologies were proposed, and the importance of interdisciplinary cooperation and the integration of artificial intelligence technology were also emphasized. This research would provide a technical foundation for increasing oil displacement efficiency, markedly augmenting EOR, and would also be imperative for improving the economic benefits and alleviating the global oil resource tension. Full article

Vehicle suspension significantly influences the safety of cargo transportation. This study presents a 14-degree-of-freedom vehicle–cargo coupling model that explicitly incorporates the frequency-dependent stiffness of air springs. Systematic parametric investigations of air spring orifice resistance, loading mass, and cargo stiffness reveal the following: (a) Compared with leaf spring suspension, air suspension vehicles attenuated the first peak of acceleration power spectral density by over 50%, while slightly amplifying the second peak; (b) When replacing leaf spring suspension with air suspension, the upper-layer cargo exhibited significantly larger vibration reductions (14% vertical, 28% pitch) than the lower-layer cargo under identical cargo parameters. The roll angle should be controlled to prevent the cargo overturning when equipping air suspensions; (c) Under light loading conditions, the vertical vibration response in upper-layer cargo is amplified. This amplification can be effectively suppressed through two complementary approaches, i.e., employing low-stiffness cushion materials and reducing orifice resistance through tunable orifices, which collectively attenuate characteristic peaks in the frequency-domain response and comprehensively mitigate the vertical vibration of cargo. These findings provide guidance for designing transportation schemes for cargo in air suspension vehicles to enhance cargo safety. Full article

This paper proposes a novel hierarchical control architecture that combines Model Predictive Control (MPC) with Explicit Model-Following Control (EMFC) to enable accurate and efficient trajectory tracking for quadrotor electric Vertical Takeoff and Landing (eVTOL) aircraft operating in urban environments. The approach addresses the challenges of strong nonlinear dynamics, multi-axis coupling, and stringent safety constraints by separating the planning task from the fast-response control task. The MPC layer generates constrained velocity and yaw rate commands based on a simplified inertial prediction model, effectively reducing computational complexity while accounting for physical and operational limits. The EMFC layer then compensates for dynamic couplings and ensures the rapid execution of commands. A high-fidelity simulation model, incorporating rotor flapping dynamics, differential collective pitch control, and enhanced aerodynamic interference effects, is developed to validate the controller. Four representative ADS-33E-PRF tasks—Hover, Hovering Turn, Pirouette, and Vertical Maneuver—are simulated. Results demonstrate that the proposed controller achieves accurate trajectory tracking, stable flight performance, and full compliance with ADS-33E-PRF criteria, highlighting its potential for autonomous urban air mobility applications. Full article