The increasing demand for sustainable and environmentally friendly materials has driven research towards the development of green composites. In this work, the flax/polylactic acid(PLA) braided yarns were fabricated by braiding PLA filaments with 4 to 24 spindles on flax yarns. After curing at different temperatures(180 ℃ and 190 ℃), the core/sheath structural flax/PLA composite yarns were manufactured. According to the results of the tensile test, the flax/PLA composite yarn with 4-spindle PLA yarns as a sheath layer and at a curing temperature of 180 ℃ reached the maximum elastic modulus of about(5.79±0.65) GPa and the maximum tensile strength of about(162.17±18.18) MPa. This flax/PLA composite yarn with good mechanical properties would be suitable for green composites in the automobile manufacturing industry and building materials.

Regenerated cellulose/amylopectin blend fibers with controlled biodegradation were produced using dry-jet wet-spinning technology from cellulose/amylopectin/1-butyl-3-methylimidazolium chloride blends. Morphological, structural and chemical analyses revealed that dense, homogeneous and void-free blend fibers were prepared in a two-stage dissolution process. The blend fibers were regenerated from water and treated with water or 95%(volume fraction) ethanol. However, cellulose-amylopectin interactions caused crystalline rearrangements in the blend fibers, resulting in a general decrease in crystallinity. Generally, tensile properties decreased with increasing amylopectin content, except that the blend fibers with 10%(mass fraction) amylopectin exhibited higher tensile strength than the regenerated cellulose control fibers. Ethanol treatment reduced the hydrophilicity of the blend fibers, increasing the crystallinity of the blend fibers. The blend fibers exhibited remarkable degradation, directly proportional to the amylopectin content. Despite higher crystallinity, ethanol-treated blend fibers degraded faster than water-treated fibers, indicating amylopectin and ethanol regulated the degradation.

Flexible thermoelectric(TE) materials that convert heat into electricity have been widely used in wearable electronics and other flexible devices. In this work, inorganic TE pillars were combined with thermoplastic polyurethane(TPU) to assemble a flexible string-shaped TE generator(TEG) for the fabrication of the thermoelectric fabric(TEF). Moreover, finite element analysis(FEA) was used to optimize the dimensions of the TE string and evaluate its performance. The FEA results showed that the inter-pillar spacing significantly affected the temperature difference, the output voltage and the internal resistance. A maximum power density of 3.43 μW/cm²(temperate gradient ΔT=10.5 K) was achieved by the TE string with a diameter of 3.5 mm and an inter-pillar spacing of 2 mm. However, under the experimental condition, the achievable power density of the fabricated three-dimensional(3D) TEF was limited to 29% of the simulation result because of the inclination of the TE string within the fabric concerning heat plate contact and copper wire-TE pillar connections. The actual TE string also demonstrated high flexibility and stable mechanical properties after 450 bending cycles. Thus, the study would provide a foundation for future research in developing more efficient TEFs to offer a comfortable and conformable option for wearable energy harvesting applications.

Cardiovascular disease persists as the primary cause of human mortality, significantly impacting healthy life expectancy. The routine electrocardiogram(ECG) stands out as a pivotal noninvasive diagnostic tool for identifying arrhythmias. The evolving landscape of fabric electrodes, specifically designed for the prolonged monitoring of human ECG signals, is the focus of this research. Adhering to the preferred reporting items for systematic reviews and meta-analyses(PRISMA) statement and assimilating data from 81 pertinent studies sourced from reputable databases, the research conducts a comprehensive systematic review and meta-analysis on the materials, fabric structures and preparation methods of fabric electrodes in the existing literature. It provides a nuanced assessment of the advantages and disadvantages of diverse textile materials and structures, elucidating their impacts on the stability of biomonitoring signals. Furthermore, the study outlines current developmental constraints and future trajectories for fabric electrodes. These insights could serve as essential guidance for ECG monitoring system designers, aiding them in the selection of materials that optimize the measurement of biopotential signals.

In order to solve the problem of metal impurities mixed in the production line of wood pulp nonwoven raw materials, intelligent metal detection and disposal automation equipment is designed. Based on the principle of electromagnetic induction, the precise positioning of metal coordinates is realized by initial inspection and multi-directional re-inspection. Based on a geometry optimization driving algorithm, the cutting area is determined by locating the center of the circle that covers the maximum area. This approach aims to minimize the cutting area and maximize the use of materials. Additionally, the method strives to preserve as many fabrics at the edges as possible by employing the farthest edge covering circle algorithm. Based on a speed compensation algorithm, the flexible switching of upper and lower rolls is realized to ensure the maximum production efficiency. Compared with the metal detection device in the existing production line, the designed automation equipment has the advantages of higher detection sensitivity, more accurate metal coordinate positioning, smaller cutting material areas and higher production efficiency, which can make the production process more continuous, automated and intelligent.

Automatic splicing of interrupted yarns in ring spinning has always been a problem in the industry. Factors such as low yarn strengths and environmental influence on yarn tensions make it difficult to control the yarn tension during the robotic splicing process. The purpose of this research is to design active disturbance rejection control(ADRC) for a third-order nonlinear tension system subject to external disturbances. Firstly, a third-order extended state observer(ESO) is designed to achieve the suppression and the compensation of the internal modeling error and the external disturbances of the system. Secondly, the adaptive gain error feedback control and the filtering process are designed to reduce the influence of sensor noise on the disturbance observation. Finally, the tension control during the splicing process is simulated and experimented, and the experiments show that the method has good robustness in the tension tracking task under a dynamic environment, which verifies the effectiveness of the method.

Nowadays, the internal structure of spacecraft has been increasingly complex. As its “lifeline”, cables require extensive manpower and resources for manual testing, and it is challenging to quickly and accurately locate quality problems and find solutions. To address this problem, a knowledge graph based method is employed to extract multi-source heterogeneous cable knowledge entities. The method utilizes the bidirectional encoder representations from transformers(BERT) network to embed word vectors into the input text, then extracts the contextual features of the input sequence through the bidirectional long short-term memory(BiLSTM) network, and finally inputs them into the conditional random field(CRF) network to predict entity categories. Simultaneously, by using the entities extracted by this model as the data layer, a knowledge graph based method has been constructed. Compared to other traditional extraction methods, the entity extraction method used in this study demonstrates significant improvements in metrics such as precision, recall and an F1 score. Ultimately, employing cable test data from a particular aerospace precision machining company, the study has constructed the knowledge graph based method in the field to achieve visualized queries and the traceability and localization of quality problems.

The flow field and flow state of thin-film evaporators are complex, and it is significant to effectively divide and quantify the flow field and flow state, as well as to study the internal flow field distribution and material mixing characteristics to improve the efficiency of thin-film evaporators. By using computational fluid dynamics(CFD) numerical simulation, the distribution pattern of the highviscosity fluid flow field in the thin-film evaporators was obtained. It was found that the staggered interrupted blades could greatly promote material mixing and transportation, and impact the film formation of high-viscosity materials on the evaporator wall. Furthermore, a flow field state recognition method based on radial volume fraction statistics was proposed, and could quantitatively describe the internal flow field of thin-film evaporators. The method divides the high-viscosity materials in the thin-film evaporators into three flow states, the liquid film state, the exchange state and the liquid mass state. The three states of materials could be quantitatively described. The results show that the materials in the exchange state can connect the liquid film and the liquid mass, complete the material mixing and exchange, renew the liquid film, and maintain continuous and efficient liquid film evaporation.

An alternating current(AC) microgrid is a system that integrates renewable power, power converters, controllers and loads. Hierarchical control can manage the frequency of the microgrid to prevent imbalance and collapse of the system. The existing frequency control methods use traditional proportion integration(PI) controllers, which cannot adjust PI parameters in real-time to respond to the status changes of the system. Hierarchical control driven by fuzzy logic allows real-time adjustment of the PI parameters and the method used a two-layer control structure. The primary control used droop control to adjust power distribution, and fuzzy logic was used in the voltage loop of the primary control. The secondary control was added to make up for frequency deviation caused by droop control, and fuzzy logic was used in the secondary frequency control to deal with the dynamic change of frequency caused by the disturbances of loads. The proposed method was simulated in Matlab/Simulink. In the primary control, the proposed method reduced the total harmonic distortion(THD) of two cycles of the output voltage from 4.19% to 3.89%; in the secondary control, the proposed method reduced the frequency fluctuation of the system by about 0.03 Hz and 0.04 Hz when the load was increased and decreased, respectively. The results show that the proposed methods have a better effect on frequency maintenance and voltage control of the AC microgrid.

Deep neural networks are extremely vulnerable to externalities from intentionally generated adversarial examples which are achieved by overlaying tiny noise on the clean images. However, most existing transfer-based attack methods are chosen to add perturbations on each pixel of the original image with the same weight, resulting in redundant noise in the adversarial examples, which makes them easier to be detected. Given this deliberation, a novel attention-guided sparse adversarial attack strategy with gradient dropout that can be readily incorporated with existing gradient-based methods is introduced to minimize the intensity and the scale of perturbations and ensure the effectiveness of adversarial examples at the same time. Specifically, in the gradient dropout phase, some relatively unimportant gradient information is randomly discarded to limit the intensity of the perturbation. In the attention-guided phase, the influence of each pixel on the model output is evaluated by using a soft mask-refined attention mechanism, and the perturbation of those pixels with smaller influence is limited to restrict the scale of the perturbation. After conducting thorough experiments on the NeurIPS 2017 adversarial dataset and the ILSVRC 2012 validation dataset, the proposed strategy holds the potential to significantly diminish the superfluous noise present in adversarial examples, all while keeping their attack efficacy intact. For instance, in attacks on adversarially trained models, upon the integration of the strategy, the average level of noise injected into images experiences a decline of 8.32%. However, the average attack success rate decreases by only 0.34%. Furthermore, the competence is possessed to substantially elevate the attack success rate by merely introducing a slight degree of perturbation.

The transition towards the fifth generation(5G) of communication systems has been fueled by the need for compact, high-speed and wide-bandwidth systems. These advancements necessitate the development of novel and highly efficient antenna designs characterized by the compact size. In this paper, a novel antenna design with a hexagonal-shaped resonating element and two U-shaped open-ended stubs is presented. Millimeter-wave(mmWave) frequency range suffers from attenuation due to atmosphere and path loss because of higher frequencies. To address these issues, the deployment of a high-gain antenna is imperative. This design is created through an evolutionary process to work best in the mmWave frequency range with a high gain. A thin Rogers RT5880 substrate with a thickness of 0.254 mm, a dielectric constant of 2.3 and a loss tangent of 0.000 9 supports the copper-based radiating element. A partial ground plane with a square slot and trimmed corners at the bottom enhances the antenna's bandwidth. The single-element antenna exhibits a wide bandwidth of nearly 6 GHz and a gain of 4.58 dBi. By employing the proposed antenna array, the antenna gain is significantly enhanced to 14.90 dBi while maintaining an ultra-compact size of 24 mm × 46 mm at the resonant frequency of 31 GHz. The antenna demonstrates a wider impedance bandwidth of 15.73%(28-34 GHz) and an efficiency of 94%. The proposed design works well for 5G communication and satellite communication, because it has a simple planar structure and focused dual-beam radiation patterns from a simple feeding network.