Search Results (38)

Under the dual impetus of the “Dual Carbon” goals and the construction of smart grids, the development of new energy power infrastructure has been fully realized. The All-Fiber Optical Current Transformer (FOCT), leveraging its unique advantages, is in the process of supplanting traditional current transformers to become the core component of power system monitoring equipment. Currently, to achieve higher precision and stability in magnetic field or current detection, FOCT structures frequently incorporate active components such as Y-waveguides and phase modulators, and closed-loop feedback systems are often used in demodulation. This has led to issues of high cost, complex demodulation, and difficult maintenance, significantly hindering the further advancement of FOCTs. Addressing the problems of high cost and complex demodulation, this paper proposes a passive multiplexing structure that achieves time-domain multiplexing of pulsed sensing signals, designs a corresponding intensity demodulation algorithm, and applies this structure to FOCTs. This enables low-cost, simple-demodulation current sensing, which can also be utilized for magnetic field detection, showcasing vast application potential. Full article

Structural batteries, also known as “massless batteries”, integrate energy storage directly into load-bearing materials, offering a transformative alternative to traditional Li-ion batteries. Unlike conventional systems that serve only as energy storage devices, structural batteries replace passive structural components, reducing overall weight while providing mechanical reinforcement. However, achieving uniform and efficient coatings of active materials on carbon fibers remains a major challenge, limiting their scalability and electrochemical performance. This study investigates ultrasonic spray coating as a precise and scalable technique for fabricating composite cathodes in structural batteries. Using a computer-controlled ultrasonic nozzle, this method ensures uniform deposition with minimal material waste while maintaining the mechanical integrity of carbon fibers. Compared to traditional techniques such as electrophoretic deposition, vacuum bag hot plate processing, and dip-coating, ultrasonic spray coating achieved superior coating consistency and reproducibility. Electrochemical testing revealed a specific capacity of 100 mAh/g_LFP with 80% retention for more than 350 cycles at 0.5 C, demonstrating its potential as a viable coating solution. While structural batteries are not yet commercially viable, these findings represent a step toward their practical implementation. Further research and optimization will be essential in advancing this technology for next-generation aerospace and transportation applications. Full article

For the new type of CFRP (Carbon Fiber Reinforced Plastic) thin-walled components with a large size and weak rigid structure, due to the integration of geometric features and the reduction in the amount of parts, the assembly size transmission chain is short compared to traditional metal assembly structures. In addition, the manufacturing errors and layer parameters of large composite parts in different regions are different, and they also have a lower forming accuracy. For the current assembly method that mainly concerns geometric dimensions and tolerances, it is difficult to support precise analysis and accurate geometric error forms for different local and global regions. As a result, in practical engineering, the forced method of applying a local clamping force is inevitably adopted to passively reduce and compensate for assembly errors. However, uneven stress distribution and possible internal damage occur. To avoid the assembly quality problems caused by forced clamping operations, the research status on the optimization of forced clamping process parameters before assembly, the flexible position–force adjustment of fixtures during assembly, and gap compensation and strengthening before assembly completion was analyzed systematically. The relevant key technologies, such as force limit setting, geometric gap reduction, stress/damage evolution prediction, the reverse optimization of clamping process parameters, and precise stress/damage measurement, are proposed and resolved in this paper. With the specific implementation solutions, geometric and mechanical assembly status coupling analysis, active control, and a collaborative guarantee could be achieved. Finally, future research work is proposed, i.e., dynamic evolution behavior modeling and the equalization of the induction and control of physical assembly states. Full article

The continuous increase in the operating speed of rail vehicles demands higher requirements for passive safety protection and lightweight design. This paper focuses on an energy-absorbing component (circular tubes) at the end of a train. Thin-walled carbon fiber-reinforced polymer (CFRP) tubes were prepared using the filament winding process. Through a combination of sled impact tests and finite element simulations, the effects of a chamfered trigger (Tube I) and embedded trigger (Tube II) on the impact response and crashworthiness of the structure were investigated. The results showed that both triggering methods led to the progressive end failure of the tubes. Tube I exhibited a mean crush force (MCF) of 891.89 kN and specific energy absorption (SEA) of 38.69 kJ/kg. In comparison, the MCF and SEA of Tube II decreased by 21.2% and 21.9%, respectively. The reason for this reduction is that the presence of the embedded trigger in Tube II restricts the expansion of the inner plies (plies 4 to 6), thereby affecting the overall energy absorption mechanism. Based on the validated finite element model, a modeling strategy study was conducted, including the failure parameters (DFAILT/DFAILC), the friction coefficient, and the interfacial strength. It was found that the prediction results are significantly influenced by modeling methods. Specifically, as the interfacial strength decreases, the tube wall is more prone to circumferential cracking or overall buckling under axial impact. Full article

Passive Optical Networks (PONs) are telecommunication technologies that use fiber-optic cables to deliver high-speed internet and other communication services to end users. PONs split optical signals from a single fiber into multiple fibers, serving multiple homes or businesses without requiring active electronic components. PONs planning involves designing and optimizing the infrastructure for delivering fiber-optic communications to end users. The main contribution of this paper is the introduction of tailored operators within a genetic algorithm (GA) optimization approach for PONs planning. A three vector and an aggregator vector are devised to account, respectively, for physical and logical connections of the network, facilitating the execution of GA operators. This codification and these operators are versatile and can be applied to any population-based algorithm, not limited to GAs alone. Furthermore, the proposed operators are specifically designed to exploit the unique characteristics of PONs, thereby minimizing the occurrence of unfeasible solutions and accelerating convergence towards an optimal network design. By incorporating these specialized operators, this research aims to enhance the efficiency of PONs planning, ultimately leading to reduced costs and improved network performance. Full article

Integrated photonics on Silicon-On-Insulator (SOI) substrates is a well developed research field that has already significantly impacted various fields, such as quantum computing, micro sensing devices, biosensing, and high-rate communications. Although quite complex circuits can be made with such technology, everything is based on a few ’building blocks’ which are then combined to form more complex circuits. This review article provides a detailed examination of the state of the art of integrated photonic building blocks focusing on passive elements, covering fundamental principles and design methodologies. Key components discussed include waveguides, fiber-to-chip couplers, edges and gratings, phase shifters, splitters and switches (including y-branch, MMI, and directional couplers), as well as subwavelength grating structures and ring resonators. Additionally, this review addresses challenges and future prospects in advancing integrated photonic circuits on SOI platforms, focusing on scalability, power efficiency, and fabrication issues. The objective of this review is to equip researchers and engineers in the field with a comprehensive understanding of the current landscape and future trajectories of integrated photonic components on SOI substrates with a 220 nm thick device layer of intrinsic silicon. Full article

There is increasing interest in the use of novel elastomers with inherent or modified advanced dielectric and mechanical properties, as components of dielectric elastomer actuators (DEA). This requires corresponding techniques to assess their electro-mechanical performance. A common way to test dielectric materials is the fabrication of actuators with pre-stretch fixed by a stiff frame. This results in the problem that the electrode size has an influence on the achievable actuator displacement and strain, which is detrimental to the comparability of experiments. This paper presents an in-depth study of the active-to-passive ratio with the aim of investigating the influence of the coverage ratio on uniaxial actuator displacement and strain. To model the effect, a simple lumped-parameter model is proposed. The model shows that the coverage ratio for maximal displacement is 50%. To validate the model results, experiments are carried out. For this, a rectangular, fiber-reinforced DEA is used to assess the relation of the coverage ratio and deformation. Due to the stiffness of the fibers, highly anisotropic mechanical properties are achieved, leading to the uniaxial strain behavior of the actuator, which allows the validation of the one-dimensional model. To consider the influence of the simplifications in the lumped-parameter model, the results are compared to a hyperelastic model. In summary, it is shown that the ratio of the active-to-passive area has a significant influence on the actuator deformation. Both the model and experiments confirm that an active-to-passive ratio of 50% is particularly advantageous in most cases. Full article

In this research, we present and design a blended wavelength-division-multiplexing passive optical network (WDM-PON) architecture to deliver both baseband and free-space optical (FSO) signals by using two wavelength bands over an available bandwidth to avoid the signal interference. Only using few additional components in the optical line termination (OLT) and optical network unit (ONU)/optical wireless unit (OWU) can achieve self-protected operation in the presented hybrid fiber-FSO access network against fiber breakage. In the measurement, eight WDM wavelengths with 24.3 Gbit/s on-off keying (OOK) modulation format are applied to verify and discuss the bit error rate (BER) performances of baseband and FSO signals, respectively, through 25 km fiber and 2 m wireless FSO connections. Therefore, the presented PON not only can deliver both baseband and FSO traffics, but can also provide a self-restored mechanism against fiber fault. Full article

We reported on the generation of 99.8 fs, 25 kW peak-power, dispersion-managed pulses directly from a passively mode-locked Yb-fiber laser oscillator with a figure-of-9 configuration. The introduction of strongly injected pump power and optical components with a high damage threshold enables high-power operation, while the polarization-maintaining (PM) fiber supports environmentally stable self-started mode-locking. Mode-locking in the soliton-like and negative-dispersion regime is characterized by the dispersion management via tuning the separation distances between a pair of gratings inside the cavity. The oscillator generates stable pulses with up to 40.10 mW average power at a 16.03 MHz repetition rate, corresponding to a pulse energy of 2.5 nJ. To the best of our knowledge, it is the highest peak-power directly obtained by a laser oscillator with a figure-of-9 configuration. Full article

Bi-material composite structures with continuous fibers embedded on polymer substrates exhibit self-morphing under thermal stimulus induced by the different coefficients of thermal expansion (CTE) between the two constituent materials. In this study, a series of such structures are investigated in terms of fiber patterns and materials to achieve programmable and reversible transformations that can be exploited for thermal management applications. Stemming from this investigation’s results, an axial cooling fan prototype is designed and fabricated with composite blades that passively alter their shape, specifically their curvature and twist angle, under different operating temperatures. A series of computational fluid dynamics (CFD) simulations are performed, subjecting the fan’s geometry to different flow temperatures to measure differences in airflow deriving from the induced shape transformations. Corresponding experimental trials are additionally performed, aiming to validate the simulation results. The results indicate the potential of utilizing bilayer self-morphing configurations for the fabrication of smart components for cooling purposes. Full article

Fiber-to-the-home (FTTH) networks are seen as the most future-proof technology to offer increasing bandwidth to customers. By utilizing passive optical network (PON) technology, they provide flexibility and capability to carry higher bandwidths as compared to the legacy copper-based access network. Optical performance monitoring could potentially enable higher stability, reconfigurability, and flexibility in a self-managed optical network. This paper will describe the specific fiber impairments that affect the quality of service for fiber-to-the-home networks. The impairment needs to be monitored and restored. The proposed solution will utilize a photodiode and optical switch as the main components, can easily be integrated with the ONU through the optical interface, and will be referred to as ‘PROMO’. With this scheme, the protection and restoration mechanisms are archived through the detection and availability of the downstream signal from the OLT. The results show that the received power, BER values, and maximum Q factor are acceptable for both simulation and experimental conditions in the case of normal and protection conditions. Full article

The need for energy-storing technologies with lower environmental impact than Li-ion batteries but similar power metrics has revived research in Zn-based battery chemistries. The application of bio-based materials as a replacement for current components can additionally contribute to an improved sustainability of Zn battery systems. For that reason, bacterial cellulose (BC) was investigated as separator material in Ni-Zn batteries. Following the biotechnological production of BC, the biopolymer was purified, and differently shaped separators were generated while surveying the alterations of its crystalline structure via X-ray diffraction measurements during the whole manufacturing process. A decrease in crystallinity and a partial change of the BC crystal allomorph type I_α to II was determined upon soaking in electrolyte. Electrolyte uptake was found to be accompanied by dimensional shrinkage and swelling, which was associated with partial decrystallization and hydration of the amorphous content. The separator selectivity for hydroxide and zincate ions was higher for BC-based separators compared to commercial glass-fiber (GF) or polyolefin separators as estimated from the obtained diffusion coefficients. Electrochemical cycling showed good C-rate capability of cells based on BC and GF separators, whereas cell aging was pronounced in both cases due to Zn migration and anode passivation. Lower electrolyte retention was concluded as major reason for faster capacity fading due to zincate supersaturation within the BC separator. However, combining a dense BC separator with low zincate permeability with a porous one as electrolyte reservoir reduced ZnO accumulation within the separator and improved cycling stability, hence showing potentials for separator adjustment. Full article

The objective of this article is to present the results of our investigations concerning the environmental conditions that can be expected during the embedding process into fibre metal laminates and the consequences for a sensor node for structural health monitoring. The idea behind this investigation is to determine for which manufacturing conditions the integration of sensor nodes into the material can be done and to identify limits for this. The sensor nodes consist of commercially available integrated circuits and passive components soldered onto an adhesive-less flexible printed circuit board. They are tested under conditions above their specified limits, to find out if they are still working reliably after experiencing 155 min of 180 ${}^{\circ }\mathrm{C}$ and 7 bar of pressure. Apart from occurring temperature damage, the effect of surrounding fibres potentially pushing away the components under the amount of pressure of the manufacturing process, as well as the potential of shorts due to conductive fibers are investigated and suitable solutions to prevent this are evaluated. One experiment exceeding the typical requirements of a fiber metal laminate embedding process for structural components will be conducted at 250 ${}^{\circ }\mathrm{C}$ for 10 h, in order to determine the limits of embedding electronic sensor nodes. This time and temperature combination is expected to cause irreversible damage to the electronic system. Results show that it is possible to integrate electronics into materials under conditions far above their specifications when precautions are taken but also that there are limits that must not be exceeded during the embedding process. Full article

A low-temperature plasma-enhanced chemical vapor deposition grown germanium (Ge) thin-film is employed as a nonlinear saturable absorber (SA). This Ge SA can passively mode-lock the erbium-doped fiber laser (EDFL) for soliton generation at a central wavelength of 1600 nm. The lift-off and transfer of the Ge film synthesized upon the SiO₂/Si substrate are performed by buffered oxide etching and direct imprinting. The Ge film with a thickness of 200 nm exhibits its Raman peak at 297 cm⁻¹, which both the nanocrystalline and polycrystalline Ge phases contribute to. In addition, the Ge thin-film is somewhat oxidized but still provides two primary crystal phases at the (111) and (311) orientations with corresponding diffraction ring radii of 0.317 and 0.173 nm, respectively. The nanocrystalline structure at (111) orientation with a corresponding d-spacing of 0.319 nm is also observed. The linear and nonlinear transmittances of the Ge thin-film are measured to show its self-amplitude modulation coefficient of 0.016. This is better than nano-scale charcoal and carbon-black SA particles for initiating the mode-locking at the first stage. After the Ge-based saturable absorber into the L-band EDFL system without using any polarized components, the narrowest pulsewidth and broadest linewidth of the soliton pulse are determined as 654.4 fs and 4.2 nm, respectively, with a corresponding time–bandwidth product of 0.32 under high pumping conditions. Full article

The dependence of the output pulse characteristics of a Mamyshev fiber oscillator on cavity parameters is investigated in detail. We analyze the change in pulse spectrum bandwidth, pulse duration, dechirped pulse duration and chirp with the change in fiber group velocity dispersion, fiber nonlinearity, gain, and filters by putting forward a numerical model. In particular, as one of the most important components, the effect of filters bandwidth and the central wavelength interval between them is discussed. The passive fibers are classified into two kinds according to their locations in the cavity, which are the one before the gain fiber and the one after the gain fiber. Numerical simulation results show that a wide spectrum can be obtained by increasing the nonlinearity of the second passive fiber, while the change in nonlinearity of the first passive fiber has a weak effect on spectrum broadening. A wide spectrum could also be obtained by increasing the nonlinearity or the small-signal gain coefficient of the gain fiber. A Yb-doped Mamyshev fiber oscillator is demonstrated. The results show the increase in pump power, which agrees reasonably well with the numerical simulation results. Full article