Search Results (2,198)

Background: Radiation dermatitis (ARD), particularly its most severe form, moist desquamation (MD), is a frequent and distressing complication of external beam radiotherapy (RT) in head and neck (H&N) cancer patients. Standard management often provides limited benefit for healing and symptom control. Silicone-based foam dressings, including Mepilex Lite and Mepilex Ag, may offer atraumatic adherence, moisture balance, and pain reduction. This study evaluated their real-world effectiveness for MD after conventional RT. Methods: Ten H&N cancer patients with clinically confirmed MD post-radiotherapy were prospectively followed until healing. Patients received Mepilex Lite or Mepilex Ag based on exudate level and infection risk, with dressings changed every three days. Patient- and healthcare provider-reported measures were collected throughout follow-up. The primary endpoint was time to MD resolution, defined as healing to grade 1 skin status. Secondary endpoints included changes in symptom burden, dressing tolerability and satisfaction, and adverse events. Results: Median age was 69 years (range 44–78). All wounds healed to grade 1, with a mean time of 8.6 days (SD 3.9). No infections or adverse events occurred. Pain, burning, and interference with daily activity decreased, and most patients reported improved comfort. Conclusions: In this small prospective cohort study, use of Mepilex dressings was associated with rapid healing, good tolerability, and improvement in patient-reported symptoms of acute radiation dermatitis. These findings suggest that Mepilex dressings may be a promising management option and warrant evaluation in larger comparative studies. Full article

This paper presents and validates a unified spreadsheet-based framework for engineering mechanics education and preliminary design. Three modules are integrated within a single openly available workbook: multi-point resultant force and moment computation; axial normal stress with stress concentration effects for three geometric configurations (plate with hole, shoulder plate, stepped shaft); and beam deflection for simply supported and cantilever configurations under point loads. All governing equations are implemented as explicit closed-form expressions validated against analytical reference solutions for six independent cases; relative errors fall below ${10}^{-10}$ in all cases. Three worked exercises demonstrate the practical scope of the framework. A biomechanical multi-point force system yields joint moments of $-6880$, −33,421, and −58,241 N·mm at the wrist, elbow, and shoulder, respectively. A tensile shoulder plate with $K_t\approx 1.85$ produces ${\sigma }_{max}=232$ MPa against ${\sigma }_y=200$ MPa, identifying a design failure; a parametric redesign with fillet radius $r=10$ mm reduces $K_t$ to approximately 1.59 and ${\sigma }_{max}$ to approximately 198.7 MPa, restoring structural safety. A cantilever beam subjected to a 20,000 N tip load yields a maximum deflection of 13,133 μm. The framework constitutes a validated intermediate layer between manual analytical derivations and high-fidelity numerical simulations, applicable to preliminary design, parametric sensitivity studies, and engineering education at the linear elastic level. Full article

The rapid expansion of wireless connectivity has led to vast amounts of radio-frequency (RF) energy being continuously radiated into the environment, much of which is dissipated due to severe propagation losses. Recycling this otherwise wasted RF energy is, therefore, a critical enabler for energy-efficient and sustainable wireless systems. RF energy harvesting nodes and passive backscatter communication devices provide promising solutions by enabling battery-less or low-maintenance operation for future green networks. However, both paradigms suffer from fundamental limitations, including restricted communication range, near–far effects, and insufficient harvested energy at extended distances. This review examines how cooperative relays can address these challenges by harvesting ambient RF energy and assisting both information transfer and power delivery. From a communication perspective, we review cooperative backscatter communication and harvest-then-transmit (HTT) protocols, highlighting how multi-hop relaying significantly extends coverage and improves throughput for energy-constrained devices. Particular emphasis is placed on tag-to-tag (T2T) backscatter systems, relay-assisted architectures, decode-and-forward and amplify-and-forward protocols, and optimal multi-access time allocation strategies that mitigate the doubly near–far problem in passive networks. From an energy-transfer perspective, the review is structured around three pillars: wireless power transfer (WPT), multi-hop energy transfer (MET), and integrated charging-and-sensing frameworks. We discuss relay deployment and placement optimisation, UAV-enabled mobile energy relays, waveform and beam-forming design, and the transition from idealised linear harvesting models to practical nonlinear rectification models. Key practical constraints, such as regulatory limits, safety compliance, self-interference, protocol overhead, synchronisation, and imperfect channel knowledge, are systematically reviewed. The paper concludes by identifying the scalability limits of multi-hop cooperative systems, outlining how the joint optimisation of energy relaying and cooperative communication enables RF energy recycling for sustainable, low-carbon wireless networks and highlighting open challenges and future research directions. Full article

In this study, the influence of thermal loading in a supersonic flight environment on the mechanical stiffness of elastic structures and the corresponding aeroelastic stability limits is investigated analytically. Recognizing that elevated temperatures inherently alter constituent elastic properties, a temperature-dependent continuous elasticity framework is incorporated directly into the governing differential operators of the structural domain. The macro-mechanical behavior of representative panel- and wing-type elements is modeled utilizing the Euler–Bernoulli beam formulation, while high-speed supersonic aerodynamic effects are represented through linearized first-order piston theory. The continuous spatial displacement fields are discretized by means of a modal expansion, and the coupled aeroelastic system is subsequently transformed into a finite set of dynamic state-space equations using the Ritz–Galerkin truncation method. The numerical and analytical outputs demonstrate that aerothermal softening not only induces continuous erosion in the material stiffness but also directly modulates the aeroelastic pole trajectories, thereby prematurely contracting the safe supersonic flight envelope. The primary novelty of the proposed framework lies in the derivation of explicit analytical expressions that directly map temperature-dependent stiffness variations onto supersonic aeroelastic instability boundaries. Because this approach is formulated in a generalized analytical form, it can be applied across diverse material systems, geometric profiles, and thermal conditions with reduced computational overhead compared to full fluid–structure interaction solvers, thereby providing a theoretical basis for preliminary stability assessment of supersonic aerospace configurations operating under high-temperature conditions. Full article

Shallow-buried coal seams in western China are commonly overlain by deeply incised gully terrain, where mining is often accompanied by coal-wall spalling and abnormal increases in support resistance, which affect safe and efficient production. To investigate overburden failure during shallow-buried coal seam mining under gully terrain and to clarify the support–resistance mechanism, a typical working face was selected as the engineering background. Physical similarity simulation, 3DEC numerical simulation, and theoretical analysis were used to analyze overburden failure characteristics and the coupled evolution of the stress, displacement, and fracture fields. Mechanical models of key-stratum fracture and a support–resistance estimation model were established to reveal the influence of overburden-thickness variation on key-stratum fracture and support resistance. The results show that overburden failure in gully areas exhibits pronounced stage-dependent and asymmetric characteristics. In the similarity simulation, the initial fracture intervals of the key stratum in the downhill section were 32 m and 36 m, indicating an asymmetric fracture pattern with a shorter span on the left side and a longer span on the right side. In the uphill section, the periodic fracture interval of the key stratum decreased from 30 m to 24 m as the overburden thickness increased. During overburden failure in gully areas, the three fields exhibited a coupled relationship: stress concentration at the working face caused overburden failure and subsidence, which promoted fracture propagation, whereas stress redistribution in the goaf compacted the fractured overburden and promoted fracture closure. The overburden failure characteristics differed significantly between mining stages. During downhill mining, the key stratum behaved as a fixed-ended beam with a relatively large fracture interval, whereas during uphill mining, it formed a cantilever beam, and its fracture interval decreased with increasing overburden thickness. The loading mechanism of support resistance was shown to be jointly controlled by variations in gully overburden thickness and key-stratum fracture. During downhill mining, support loading increased gradually under the support of the fixed-ended beam key stratum. During uphill mining, support loading exhibited periodic abrupt increases under the combined effects of increasing overburden thickness and periodic fracture of the cantilever-beam key stratum. These findings provide a theoretical basis for strata pressure control at working faces in gully areas. Full article

As the core sensor of inertial measurement units, the reliability of Micro-Electro-Mechanical Systems (MEMS) gyroscopes is critical for long-term navigation and motion control applications. To bridge the mechanism-data gap in MEMS multi-mechanism degradation modeling, this paper proposes a physics-informed dual-indicator reliability assessment framework based on Wiener processes. Two degradation indicators under consideration are frequency-related degradation caused by stiffness degradation and Q-factor degradation caused by damping degradation, for which corresponding physics-embedded stochastic degradation models are formulated. The two indicators are normalized and fused through a generalized weighted limit state function, where failure is defined as gyroscope-level performance failure. Closed-form reliability expressions are derived for linear limit states, while Monte Carlo simulation is used for nonlinear cases. Reduced-order multiphysics simulation cases, including a double-ended fixed beam and a cantilevered MEMS mass block, are used to demonstrate the mechanism-to-indicator-to-reliability modeling procedure. The results show that the proposed dual-indicator framework provides more balanced reliability assessment than single-indicator analysis under the simulation setting. The proposed method offers an alternative mechanism-informed approach for reliability analysis and lifetime prediction of other MEMS devices. Full article

To address the large deformation and instability of gob-side entry roofs in soft, thick coal seams induced by residual cavities left by hydraulic flushing, the 1609 working face of Jiulishan Coal Mine was selected as the engineering background. Field investigation, numerical simulation, and industrial field testing were combined to investigate the deformation and failure characteristics of surrounding rock and the corresponding control technology for gob-side entries with cavity-bearing roofs. The results indicate that residual cavities created by hydraulic flushing disrupt the stress transfer path within the roof, causing stress field distortion and expansion of tensile stress zones, thereby significantly weakening the roof load-bearing capacity. As the cavity size increases, the surrounding rock deformation and plastic zone continuously expand. When the cavity size exceeds 1.0 m, roof subsidence exhibits a nonlinear increase, and the fractured zone around the cavity connects with the roof plastic zone, forming a continuous failure band that serves as the key factor leading to surrounding rock instability. Based on the deformation characteristics of the cavity-bearing roof, namely shallow fragmentation, deep-seated separation, and structural instability, a collaborative control technology consisting of multi-level cable bolts, steel-beam reinforcement, and grouting through injection pipes was proposed. By establishing a shallow–intermediate–deep hierarchical load-bearing structure and reinforcing the fractured cavity zone through grouting, the technology reconstructs the surrounding rock load-bearing system and optimizes the stress environment. Field application results show that, for a roof containing a 1.5 m cavity, the maximum roof subsidence and separation were controlled within 102 mm and 55 mm, respectively, and the roadway maintained a stable condition throughout the monitoring period. The findings provide both a theoretical basis and engineering guidance for surrounding rock control of gob-side entries with cavity-bearing roofs in soft, thick coal seams. Full article

Purpose: To develop an accelerator neutron source suitable for boron neutron capture therapy—a new promising method for treating malignant tumors—and to develop dosimetry tools and methods. Methods: Research into the transport and acceleration of a beam of charged particles, development and manufacture of an accelerator neutron source, study of the radiation generated, and development and implementation of dosimetry tools and methods. Results: A facility called VITA has been created, which includes a tandem electrostatic accelerator of an original design for producing a 2.3 MeV 10 mA proton beam, a lithium target for generating neutrons in the ⁷Li(p,n)⁷Be reaction, and a beam shaping assembly for forming a therapeutic neutron beam. The facility at the institute is used for scientific research, the facility in Xiamen (China) is used for clinical trials, and the facility in Moscow (Russia) will soon be used for clinical trials. Also, new tools and methods for measuring the boron dose, γ-ray dose, and sum of the fast neutron dose and the nitrogen dose have been proposed and implemented. The conducted studies demonstrated the high efficiency of the VITA^® facility, the first possibility of implementing prompt γ-ray spectroscopy for boron imaging, and the first possibility of implementing lithium neutron capture therapy, which has advantages over BNCT, and also presented the results of the development of new tools and methods for measuring the boron dose, γ-ray dose, and the sum of the fast neutron dose and the nitrogen dose. Conclusions: The authors strongly recommend using prompt γ-ray spectroscopy in treatment and developing lithium neutron capture therapy, including in combination with BNCT, and note the high efficiency, reliability and compactness of the VITA^® facility. Full article

The bending stiffness of cables is an important influencing parameter in the analysis of cable structures, and the modeling of cables with bending stiffness has always been a key concern. This paper proposes an accurate beam formulation for planar cables with bending stiffness, in which the deformation–strain relationship is accurately described, thus enabling the geometrically exact form finding of planar cables. After the kinematics of the cable geometry are described, the strong- and weak-form equilibrium equations of the cable are derived, and then the finite element implementations are presented. Three typical examples of cable structures are also presented; the numerical results demonstrate that the presented beam formulation shows stable and accurate numerical performance. The proposed formulation achieves rapid convergence when the number of elements reaches 20. The analysis of a suspension bridge shows that considering bending stiffness has little influence on the completed bridge state, with the error between the calculated hanger forces and the design values remaining within 1.5%. However, in the free cable state, considering bending stiffness causes a saddle pre-offset variation of approximately 5 cm, while the sag difference reaches approximately 1 m. The results demonstrate that the proposed formulation is of significant importance for planar cable form finding problems. Full article

With the integrated development of high-speed railways and urban underground rail transit, large high-speed railway station buildings are often seamlessly connected or even co-constructed with subway structures, forming a complex structural system that integrates high-speed rail, subway, and station buildings. To investigate the dynamic performance of such “ integrated station-bridge” station buildings constructed with subways, this paper takes Yichang North Station as an engineering case study and examines its vertical dynamic characteristics under multi-source train-induced loads. The station adopts a structural configuration where the station tracks are fully integrated with the station building, while the main lines are separated from it. To accurately simulate the entire process of train operation, this study established a refined “train-track-station” spatially coupled dynamics model that incorporates high-speed and subway trains, tracks, and the station structure. Based on this model, various operational scenarios were systematically analyzed, including high-speed trains passing at different speeds, parallel operation of multiple train lines, and combined operation of high-speed and subway trains. The results demonstrate that, when single or multiple high-speed train lines pass through the station at the design entry speed of 80 km/h, the vertical vibration acceleration of the elevated waiting level meets human comfort standards. The train-induced vibration response is transmitted and superimposed along the “column–beam–slab” path, resulting in localized acceleration peaks at the mid-span regions of beams and slabs directly above the tracks. Second, the impact of subway train operation alone on the vibration of the elevated level is significantly weaker than that of high-speed trains. Furthermore, under combined high-speed and subway train operations, the additional vibration contribution from subway trains shows a decreasing trend as the number of simultaneously operating high-speed train lines increases. The findings of this study validate the effectiveness of the structural design of Yichang North Station in terms of train operational safety and passenger waiting comfort. The revealed patterns of multi-source vibration transmission and superposition can provide important theoretical and numerical references for the dynamic optimization design and vibration control of similar integrated transportation hub structures. Full article

One of the main technological challenges in plasma wakefield acceleration (PWFA) research and development is achieving stable and reproducible acceleration. In particular, for PWFA schemes based on particle-driven plasma wave excitation, beam stability and timing jitter are increasingly critical. In these configurations, magnetic or radio-frequency (RF) compression schemes are often used, and the beam time-of-arrival jitter at the end of the linear accelerator can be strongly correlated with the phase noise of RF accelerating structures operated off-crest. For this reason, since 2008, an RF phase fast-feedback system acting within each RF pulse has been successfully implemented at Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (LNF-INFN) at the Sources for Plasma Accelerators and Radiation Compton with Laser And Beam (SPARC_LAB) facility, operating on both S-band ($2.856$ GHz) and C-band ($5.712$ GHz) klystrons. This paper presents the upgrade and optimization of the fast-feedback system for an S-band klystron powered by a pulse-forming network modulator. This technology introduces significantly higher intrinsic phase noise than, for instance, solid state-based modulators. It is therefore essential to minimize such phase fluctuations to keep the machine stability under control. Both the feedback hardware (electronic boards and RF circuitry) and the software (controller and user interface) have been upgraded. Tests performed at SPARC_LAB achieved a reduction in klystron-induced jitter of a factor of 30, reaching values below 15 fs rms on both power plants. Moreover, adding a remote control of the feedback loop enabled a straightforward optimization of the operating point, allowing the phase stability performance to be pushed close to its practical limits. A detailed analysis of RF phase noise measurements with the fast-feedback loop in operation is also presented. Full article

This paper proposes a multi-sensor fusion autonomous navigation method integrating a nine-axis IMU, the Leishen C16 mechanical LiDAR, and the LakiBeam1L single-line LiDAR, aimed at addressing issues such as track slippage and positioning drift that commonly occur in tracked chassis operating under continuously changing conditions on hilly slopes and farmland. IMU-derived slope and attitude information is used as a terrain prior and incorporated into adaptive ground segmentation, slope-cross-slope path cost modeling, and velocity regulation. Leishen C16 LiDAR point clouds are used for NDT scan-to-map localization and spatial obstacle representation, while the LakiBeam1L LiDAR establishes a velocity-dependent near-field safety zone for dynamic obstacle triggering and local avoidance. Python simulations were conducted in simple, general, and complex environments under five slope conditions, forming 15 environment-slope combinations. Three representative scenarios were further validated in ROS/Gazebo. To strengthen statistical reliability, 10 repeated trials were performed for each environment-slope-algorithm combination, and additional stress tests included obstacle-position perturbation, sensor noise perturbation, initial-pose perturbation, dynamic obstacle speed perturbation, and variable slope/local undulation perturbation. An isolated no-LakiBeam1L ablation, significance tests, IMU perturbation tests, planning-weight sensitivity analysis, and stronger-baseline comparison were also added. In the repeated-trial dataset, the proposed method improved the arrival rate from 23.3% to 94.7%, reduced tracking RMSE by 61.46%, reduced localization RMSE by 60.62%, and increased obstacle recall by 26.32%. Under mixed perturbations, the arrival rate of the proposed method was 81.3%, compared with 29.3% for the baseline. These results indicate improved simulation-level stability and perception reliability, while the applicability to real hilly farmland still requires hardware and field validation. Full article

There is a substantial demand for lightweight, low-profile, and conformal antenna integration on the wing platforms of unmanned aerial vehicles (UAVs). This paper presents an S-band (2–4 GHz) flexible conformal metasurface array antenna based on a highly conductive graphene-assembled film (GAF). The main contributions of this work are twofold. First, flexible and highly conductive GAF is used as the conductor together with a flexible polyimide (PI) dielectric substrate to form a GAF-based wing-conformal antenna configuration with a low-profile, lightweight, and easily conformal performance. Second, a GAF conformal antenna element is developed by combining a dipole antenna with a directive and reflective frequency selective surface (FSS), achieving effective control of the beam and stable directional radiation at 2.4 GHz. Full-wave simulations using CST Studio Suite show that the directive FSS narrows the feed beam, whereas the reflective FSS redirects and narrows the H-plane radiation. The simulated results show that the integrated wing-conformal antenna operates over 2.19–2.65 GHz and achieves a gain of 4.65 dBi at 2.4 GHz. The measurement results indicate that the GAF conformal antenna and 1 × 4 GAF conformal array antenna shows measured reflection coefficients below $-10$ dB at 2.4 GHz and effective adjacent-element isolation. In addition, simulated results indicate that the GAF array antenna can perform beam scanning within the ±40° range, verifying the beam-control capability of this structure for UAV forward communication. Overall, this work highlights the feasibility of using GAF as a conductive material for both a high-efficiency radiator and an FSS beamforming structure, offering a practical material and design approach for lightweight, low-profile, and wing-conformal airborne array antennas. Full article

Variational principles and variationally consistent boundary conditions are presented for double-layer graphene nanoribbons undergoing time-dependent and free vibrations. The van der Waals forces acting in the core region are modelled as shear and tensile–compressive effects. The nonlocal constitutive formulation of the problem is based on the sandwich beam model in order to represent the graphene nanoribbon layers as faces and van der Waals forces acting in the core region. The constitutive equations which govern the vibrations of the nanoribbons are in the form of four coupled partial differential equations involving the in-plane and out-of-plane deflections. The first part of the study involves the derivation of the variational principle for the system undergoing time-dependent vibrations. Hamilton’s principle is formulated based on the kinetic and potential energies of the system. The next section involves the freely vibrating nanoribbon system and the formulation of the variational principle for this case is given. Based on this formulation, the expressions for the Rayleigh quotients are obtained for the longitudinal natural frequency and the transverse natural frequency. The last section involves the derivation of the variationally consistent boundary conditions and the expressions for the shear force and moment at the boundaries. Full article

The present study deals with the nonlinear forced vibration of an axially functionally graded beam subjected to an electromagnetic actuator, moving load, and Casimir force, considering the curvature of the beam and it resting on a nonlinear elastic Winkler–Pasternak foundation. The presence of an electromagnetic actuator and Casimir force besides the presence of mechanical impact (moving load) and nonlinear elastic foundation is a characteristic of a real system, but this has not been studied in this form until now, currently representing a remaining gap. The governing differential equations of motion in the considered system are based on Euler–Bernoulli beam theory and von Kármán geometric nonlinearity. The material properties are expressed according to a power law function through the thickness direction. We point out that the present study is the first to consider the curvature in combination with electromagnetic actuation, Casimir force, an elastic foundation, and moving load. Unlike in other works, axial inertia is not assumed to be negligible in our investigation. The Optimal Homotopy Asymptotic Method is employed to obtain an approximate analytical expression for the nonlinear dynamic response and the nonlinear frequency. The solutions obtained are very accurate in comparison with numerical solutions, and our procedure is simple and easy to implement for nonlinear problems. The local stability near the primary resonance and internal resonance is analyzed by means of the variable expansion method, the homotopy perturbation method, equilibrium points, the Jacobian matrix, and the Routh–Hurwitz criterion. Full article