Search Results (1,575)

The development and maintenance of the nervous system depend on a tightly regulated intracellular transport network in which kinesin superfamily (KIF) motor proteins drive microtubule-based delivery of synaptic vesicle precursors, organelles, mRNAs, and signaling components along axons and dendrites. Disruption of this machinery underlies a clinically heterogeneous spectrum of neurodevelopmental disorders (NDDs), including intellectual disability, epilepsy, autism spectrum disorder, microcephaly, malformations of cortical development, spasticity, and axonal neuropathy. Here, we synthesize current knowledge on how kinesin dysfunction shapes neurodevelopment. We outline the physiological roles of kinesins in neuronal polarity, organelle and mitochondrial positioning, synaptogenesis, and progenitor division, and survey principal disease-associated genes, including KIF1A, KIF5A, KIF7, KIF11, KIF2A, KIF5C, and emerging members such as KIF14, KIF15, and KIF16B. We detail how distinct pathogenic mechanisms, such as loss of motility, impaired cargo coupling, motor hyperactivity, mitotic spindle defects, and disrupted ciliary signaling, converge on shared cellular endpoints, and how tubulin isotypes and posttranslational modifications further modulate motor output. In this review, we discuss translational implications, including variant-resolved diagnosis and precision strategies to restore transport, dampen pathological hyperactivity, or stabilize the microtubule track. Collectively, these advances reframe kinesinopathies as mechanistically stratified disorders of neuronal transport. Full article

To address the structural deformation and mechanism jamming frequently observed in critical linkages during retraction and extension of door-coupled landing gear systems, this study proposes a rigid–flexible coupled dynamic modeling approach. A representative landing gear system was studied, and a high-fidelity rigid–flexible multibody dynamics model was developed based on a conventional rigid-body framework. The left linkage, which was prone to failure, was modeled as a flexible finite element component, while the remaining parts were treated as rigid bodies. A multibody dynamics method based on nonlinear finite element was adopted, incorporating elastoplastic constitutive relations and Lagrange constraint equations. Two materials, ultra-high-strength 300M steel and high-strength 7075-T6 aluminum alloy, were evaluated to investigate the influence of structural stiffness on critical linkage stress and door kinematics during deployment. Results showed that maximum stress occurred at the hinge joint, identified as the critical region for strength assessment. The peak stress for 300M reached approximately 168 MPa, about 8.4% higher than that of 7075-T6. However, 7075-T6 exhibited lower stress oscillation frequency and superior damping performance, which helped suppress high-frequency vibration. Material selection had negligible influence on door centroid displacement, velocity, and opening angle, and the motion trajectories remained highly consistent. Full article

The contradiction between high compliance and low load-bearing capacity of flexible manipulators limits their engineering applications. Meanwhile, the theoretical modeling of the deformation and variable stiffness characteristics of flexible joints still faces considerable challenges. This paper proposes a positive-pressure double-airbag gap-constrained particle-jamming variable stiffness method and develops a novel actively variable stiffness pneumatic flexible bending joint with an integrated configuration of actuator, variable stiffness device (VSD), and primary structure. Based on classical elasticity theory and Coulomb–Amontons’ law of friction, theoretical models for the bending angle and tangential stiffness are established and verified through prototype experiments. With VSD activation, the joint reaches a bending angle of 56.35° at 0.4 MPa. At 40° forward bending, VSD activation increases the tangential stiffness from 0.167 N/mm to 0.832 N/mm, with the stiffness ratio between 40° and 0° increasing from 1.56 without VSD to 4.80 with VSD activation. Model predictions agree well with experimental data, yielding mean relative errors of 6.77% for the bending-angle model with VSD and 6.76% for the forward tangential-stiffness model with VSD activation. A coupling effect between bending deformation and stiffness is observed. The results demonstrate that the proposed joint achieves substantial stiffness regulation, providing a basis for its application in flexible robotic systems. Full article

The spontaneous emergence of macroscopic order in driven, far-from-equilibrium complex fluids lacks a generalized framework capable of bridging continuous and discrete symmetry-breaking transitions. In this study, we propose a non-equilibrium phenomenological framework that synthesizes irreversible thermodynamics, coupled Landau–de Gennes potential expansions, and active hydrodynamics. The formulation employs a single tensorial order parameter, a nonlinear state-dependent jamming mobility closure, and a generalized set of dimensionless groups to map the non-equilibrium phase space. The model predicts a sequential symmetry-breaking cascade and reproduces the emergence of polar heliconical smectic and antiferroelectric phases in driven liquid crystals, as well as the transition from isotropic active gases to macroscopic fluid flocks and active Wigner crystals in purely repulsive Janus colloids. Across these systems, a dimensionless active torque number acts as the principal bifurcation parameter, suggesting that their macroscopic structural transitions are governed by a common balance between thermodynamic and kinematic effects rather than by the details of their microscopic interactions. Full article

Objective: To critically synthesize the available evidence on the pathophysiological variants of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV) and to propose an integrative model based on otoconial location and cupular dynamics to explain their clinical presentation and therapeutic implications. Methods: A scoping review was conducted through a search of PubMed/MEDLINE, Scopus, and the Cochrane Library for studies published between January 1996 and May 2026. Studies describing pathophysiological variants, biomechanical mechanisms, nystagmus patterns, or therapeutic maneuvers in HSC-BPPV were included. A total of 26 studies met the inclusion criteria and underwent qualitative analysis. Results: Six principal mechanical configurations of horizontal canal positional vertigo were identified: long-arm canalolithiasis, short-arm canalolithiasis, canal-side cupulolithiasis, utricular-side cupulolithiasis, canalith jam, and light cupula. The available evidence suggests that these variants represent different mechanical states determined by otoconial location, otoconia–cupula interaction, canal obstruction, or alterations in cupula–endolymph density. This model explains the direction, intensity, and duration of positional nystagmus, the findings observed during the supine roll test and the bow and lean test, as well as the variability in response to repositioning maneuvers. A practical classification integrating pathophysiology, clinical findings, and treatment is proposed. Conclusions: HSC-BPPV may be more appropriately understood as a spectrum of mechanical states in which the configuration of otoconial debris and its interaction with the cupula influence the nystagmus pattern, clinical presentation, and therapeutic response. This integrative model may improve diagnostic accuracy and guide treatment selection, although prospective validation is required. Full article

Active radar jamming recognition is an important technology in modern electronic warfare (EW). With the increasingly widespread application of Digital Radio Frequency Memory (DRFM) technology, the types of jamming have become more diverse. Meanwhile, in most non-cooperative confrontation scenarios, it is difficult to obtain large-scale labeled jamming samples. The commonly used methods for radar jamming signal recognition have some limitations. One is that they require a large number of jamming samples; the other is that their recognition performance degrades severely in few-shot scenarios. To address these limitations, an Adaptive Confidence Dual-Branch Fusion Network (ACDF-Net) is proposed for few-shot jamming recognition. The Short-Time Fourier Transform (STFT) is firstly used to obtain four-channel time–frequency features of the jamming signal, which fully retains the real part, imaginary part, amplitude, and phase information of jamming. Secondly, a dual-branch complementary representation learning network is well designed to extract jamming modulation characteristics and energy-phase characteristics. Finally, an adaptive confidence fusion method controlled by learnable parameters and a multi-task supervised learning paradigm are introduced, which improve recognition accuracy and make the network more robust. A mixed dataset containing 15 types of radar active jamming (including 8 single jamming types, 3 composite jamming types, and 4 real measured jamming types) is established to verify the proposed method. Multi-dimensional validation experiments are conducted, including few-shot performance comparison under different training set proportions (3~11%), per-class recognition performance analysis, measured data generalization validation, and ablation studies of core modules. In few-shot scenarios, the OA of ACDF-Net reaches 92.81% under 3% training data proportion, which is better than the comparison algorithms. More comparative experiments show that the proposed method is better than the comparison methods. The proposed method provides an effective solution for radar active jamming recognition in few-shot and complex electromagnetic environments, which exhibits high feasibility for practical engineering applications. Full article

TBM jamming in deep, weak, squeezing ground poses a persistent threat to construction safety and schedule performance. Most existing approaches evaluate shield jamming and cutterhead jamming independently, even though TBM operation is simultaneously limited by the available thrust and torque capacities. This study proposes a unified thrust–torque assessment framework that integrates the time-dependent response of weak surrounding rock, represented by the Cvisc model, with interface-based rock–TBM contact. The framework was applied to a representative Himalayan tunnel excavated by a double-shield TBM. The calculated total tunnelling resistance and cutterhead torque demand were then evaluated against the corresponding rated machine capacities. A parametric investigation covering advance rates of 0.5–2.5 m/h, over-excavation amounts of 3–9 cm, shield lengths of 12–16.5 m, and surrounding-rock elastic moduli of 2–8 GPa identified advance rate as the dominant controllable factor, contributing 61.6% of the variance in total tunnelling resistance and 96.2% of that in cutterhead torque. Increasing the over-excavation amount primarily alleviated shield–rock contact and reduced shield frictional resistance by up to 56.2%, while exerting only a limited influence on cutterhead torque. These findings were subsequently synthesised into a project-specific jamming-risk zoning matrix, which identified low advance rates combined with small over-excavation under long-shield conditions as the most unfavourable operating regime. Field validation was conducted using 10 representative operating cases satisfying η < 0.9. The calculated responses agreed well with the monitoring data, yielding R² = 0.82 and a MAPE of 12.0% for total tunnelling resistance versus field-monitored thrust, and R² = 0.72 and a MAPE of 16.3% for cutterhead torque. The proposed framework therefore provides a quantitative basis for TBM parameter selection and jamming-risk control in squeezing ground within the validated operating range. Full article

Electronic attack (EA) using jamming signals is an essential component of electronic warfare (EW), consisting of the use of electromagnetic energy to disrupt, block or reduce the effectiveness of enemy communications, radar and navigation systems. In current conflicts, jamming EA is also successfully used against drones (air/ground), which have become an important component of modern warfare. In this context, the article proposes a method of protection against jamming (anti-jamming) for drone communications, thus achieving their resilience to electronic attack. The proposed method combines the wavelet transform with threshold SURE, adaptive filtering (LMS) and Bidirectional Long Short-Term Memory for anti-jamming resilience of 64-QAM (quadrature amplitude modulation) communication used by drones, evaluates the performance of the results obtained against electronic warfare systems and presents the open challenges for future research. Full article

The airborne corner reflector (ACR), a novel radar passive jamming device, has attracted increasing attention from researchers worldwide due to its enhanced interference coverage when suspended by a parachute. However, the directional nature of ACRs renders their effectiveness highly sensitive to in-flight attitude dynamics. By analyzing the parachute body and the corner reflector separately, we propose an improved dynamic model to describe the parachute–payload system. Key innovations include the following: (i) by introducing an 11-degree-of-freedom model for motion analysis of the parachute-mounted double-pyramid octahedron structure, the issue of imprecise analysis in previous methods has been overcome; (ii) explicit modeling of tether tension and geometric constraints is undertaken to capture the parachute–payload coupling mechanism. Numerical simulations of the steady-descent phase demonstrate convergence of the payload’s angular rates and Euler angles, and the results show good agreement with full-scale flight test data. The model strikes a favorable balance between computational efficiency and physical fidelity, and is particularly suited for dynamic analysis of non-axisymmetric payloads in parachute descent systems. Full article

Ultra-supercritical (USC) steam turbines combine severe steam conditions with increasingly frequent start-up, shutdown, and load-following operations. Their main steam valves must preserve pressure boundary integrity, sealing, and rapid actuation while non-uniform heating, creep, cyclic plasticity, oxidation, wear, and contact redistribution alter component geometry. However, the relevant evidence remains fragmented across alloy development, component thermo-mechanics, valve aerodynamics, and lifetime monitoring. This short, mechanism-oriented review integrates these domains through a material structure–function framework in which deformation relative to assembly clearance governs jamming risk. It synthesizes evidence on heat-resistant body and surface materials, 9–12% Cr steel stability, weldability and repair sensitivity, and cold, warm, and hot start-up histories. It also evaluates creep–fatigue interaction, contact, flow-induced vibration, multi-physics modeling, validation, uncertainty, monitoring, and digital twins. The synthesis shows that neither peak equivalent stress nor steady-state temperature alone can establish functional reliability. Credible assessment requires temperature-dependent material data, realistic steam-side heat transfer, cyclic constitutive behavior, initial and residual clearances, manufacturing and assembly tolerances, state-dependent friction, uncertainty analysis, and corroborating plant or inspection evidence. The most consequential research needs are valve-level validation datasets, thermal contact testing, function-oriented life criteria, and uncertainty-aware digital twins that jointly inform materials, geometry, and transient operation. Full article

This paper presents an interval-observer-based actuator fault detection and isolation (FDI) method for underactuated autonomous underwater vehicles (AUVs) under bounded hydrodynamic uncertainty and time-varying ocean currents. A locally frozen linear time-invariant (LTI) representation enables deterministic set-membership analysis, and the robust adaptive propagated interval observer (RAPIO) propagates admissible center–radius state bounds within a Lyapunov framework. Adaptivity is introduced through a reinforcement learning (RL)-augmented uncertainty-bound modulation mechanism, where an offline-trained agent scales a nonnegative channel-wise slack term without modifying the scheduled observer-gain rule or the nominal center predictor. Under the stated observer and disturbance-envelope conditions, positivity, stability, and diagnostic-channel inclusion hold for any bounded learning signal. Actuator loss-of-effectiveness (LoE) faults are represented through the actuator-effectiveness channel and detected through interval-consistency violations, enabling axis-wise isolation of surge, yaw-rate, and pitch-rate actuator faults. The same schedule-blind decision layer is additionally evaluated with structurally distinct additive-bias and stuck/jam actuator models. All stuck/jam events are detected, and bias-magnitude sweeps identify channel-wise 100%-detection boundaries with zero false alarms. A structured 72-case scenario sweep shows reliable detection, strong false-alarm rejection, and acceptable detection delays compared with benchmark observers. Full article

Jamming introduces unintentional disruptions in the system to exploit the legitimate communicating equipment. Clustered jamming considers jammers that are present in multiple groups to disrupt the intended communication. Vehicle-to-everything (V2X) transmissions are critical for smart transportation. This research considers full-duplex environment, featuring unmanned aerial vehicles (UAVs) and cellular-base-station-aided V2X (C-V2X) systems exploiting clustered jamming using 3-dimensional (3-D) beam-forming millimeter-wave antennas. UAVs are modeled as a 3-D Poisson point process (PPP), and macro-based tower-mounted base-stations (MBSs) are modeled as a 2-D PPP. Roads are modeled as a Poisson line process. The vehicular nodes (V-Ns) are modeled on each road as a 1-D PPP. The deviations of the UAV’s millimeter-wave band antenna beam follow a Normal distribution. In this paper, for a full-duplex setting, the probabilities of coverage and equipment-association, along with the efficiency of the spectrum associated with various UAV and tower-based connections, are explored in the presence of clustered jamming. The probability of coverage and association of multiple links is derived with respect to the jamming clusters, V-Ns, MBSs, UAVs, jammers’ power, and antenna beams. The results demonstrated that jamming degrades system’s efficiency. This efficiency is further degraded whenever higher 3-D beam-width deviations of the millimeter waveband antenna and jammers are present. Therefore, robust counter-scenarios should be designed for the cases where jamming signals and varying beams disrupt the network. Full article

Covert communication has emerged as a promising technique for protecting wireless transmissions by concealing the existence of legitimate communication from malicious wardens. However, achieving end-to-end covert communication in space–air–ground integrated networks (SAGINs) is challenging due to the coupled effects of satellite-to-ground relay access, ground multi-hop forwarding, and cooperative jamming. In this paper, we propose an incentive-aware end-to-end covert routing framework for SAGINs, where a low Earth orbit (LEO) satellite delivers information to a ground destination through a selected relay base station and a self-organizing ground route. We first establish a two-stage SAGIN model and characterize the satellite-to-ground covert capacity under satellite sidelobe interference, as well as the ground-route covert performance in the presence of multiple wardens and cooperative jammers. Since jammers are self-interested and incur power costs when generating artificial interference, we design an incentive mechanism to stimulate cooperative jamming for enhancing ground-route covertness. Specifically, the reward allocation and jamming-power response are jointly derived by considering both the route-dependent covertness gain and the power cost of jammers. Based on the resulting route-dependent utility, the ground routing problem is further transformed into a shortest-weighted path-finding problem. To improve the long-term stability of satellite-to-ground relay access, we model the repeated interaction between the LEO satellite transmitter and the satellite warden as a base-station selection process and develop a zero-determinant strategy to stabilize the long-term expected utility relation under different warden monitoring policies. Simulation results demonstrate that the proposed framework effectively balances satellite-to-ground covert capacity and ground-route utility, outperforms baseline relay selection schemes, and achieves stable long-term covert routing performance against uncertain warden behaviors. Full article

The safe crossing of pedestrians at traffic light-regulated intersections is ensured by the permissive and prohibitive signals provided for them and by certain priority rules that drivers in traffic flows conflicting with pedestrians must comply with. This in turn leads to the occurrence of traffic delays, which are inevitable under certain traffic conditions. The present study focuses on determining the length of traffic delays when pedestrians cross at a traffic light-regulated intersection in the city of Sofia, Republic of Bulgaria. The intersection was selected due to the high intensity of pedestrian flows established in preliminary random observations, which is provoked by its location. The study includes determining the traffic delays over a period of 12 h with full readings of these indicators for each cycle of the traffic light system during the morning and evening peak periods and with partial readings for 15 min for each cycle in the remaining hours of the study period. The results show the lack of a relationship between the waiting time of vehicles and the number of pedestrians crossing. Such an influence can be sought in the behavior and types of pedestrians and the intervals at which they enter the crosswalk. This study can assist researchers in this field in developing pedestrian crossing models and determining additional measures to increase their safety when crossing light-regulated intersections. Full article

In military confrontations, intentional suppression jamming can significantly degrade the reliability of friendly communication systems. By integrating conventional frequency hopping with spectrum sensing, cognitive frequency hopping technology can proactively avoid jammed frequency bands, thereby enhancing anti-jamming performance. This paper proposes a jamming detection and parameter estimation algorithm based on an improved YOLOv8 model. The proposed method extracts the time–frequency features of jamming signals and predicts their bounding boxes in time–frequency images. Based on the coordinates of the predicted bounding boxes, the center frequency, bandwidth, and temporal parameters of the jamming signals are estimated, thereby supporting spectrum sensing. Simulation results under MATLAB-generated signal conditions show that the proposed method achieves high detection accuracy and low mean squared relative error in the considered simulation scenarios. In addition, the proposed method maintains effective detection and parameter-estimation performance in composite jamming scenarios. This study provides a useful simulation-based reference for spectrum sensing in cognitive frequency hopping systems. Full article