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 b...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.展开更多
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 ...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.展开更多
为解决Hadoop现有调度器调度任务时不能根据任务的紧迫程度分配资源的问题,研究YARN中的资源调度机制,改进原调度器(Capacity Scheduler),提出一种基于优先级权重的Hadoop YARN(Yet Another Resource Negotiator)调度算法(Weight Schedu...为解决Hadoop现有调度器调度任务时不能根据任务的紧迫程度分配资源的问题,研究YARN中的资源调度机制,改进原调度器(Capacity Scheduler),提出一种基于优先级权重的Hadoop YARN(Yet Another Resource Negotiator)调度算法(Weight Scheduler Based on Priority)。为叶子队列设置队列优先级,结合队列资源利用率和队列优先级选择队列;将应用程序的初始权重设置为应用程序优先级的大小,通过等待时间判断是否更新权重,根据权重对队列中的应用程序进行排序,调度时优先为权重高的应用程序分配资源。实验结果表明,与原有调度算法相比,改进算法平均任务执行时间约减少141 s,平均等待时间减少34.5%,保证了用户执行任务的相对公平,提高了用户总体满意度。展开更多
In this paper, the difference of the twist insertion levels of the compact and ring spun yarns of the same count is analyzed based on the relationship of the yarn twist factor to the twist angle and the bulk density. ...In this paper, the difference of the twist insertion levels of the compact and ring spun yarns of the same count is analyzed based on the relationship of the yarn twist factor to the twist angle and the bulk density. It is proposed that the relationship of the twist angle, twist level, and the yarn diameter should be synthetically considered when evaluating the twist insertion level of the compact yarn. The twist angle of the compact yarn is smaller than that of the ring yarn with the same twist insertion level. This results from the ordered fiber arrangement and compact structure of the compact yarn. Experiment was conducted to verify the conclusions. It is also discovered that the selection of the twist factor of the compact yarn, which can be usually lower than that of the ring yarn by 10%-15%, can be determined based on the yarn tensile strength.展开更多
Yarn sensors have shown promising application prospects in wearable electronics owing to their shape adaptability, good flexibility, and weavability. However, it is still a critical challenge to develop simultaneously...Yarn sensors have shown promising application prospects in wearable electronics owing to their shape adaptability, good flexibility, and weavability. However, it is still a critical challenge to develop simultaneously structure stable, fast response, body conformal, mechanical robust yarn sensor using full microfibers in an industrial-scalable manner. Herein, a full-fiber auxetic-interlaced yarn sensor(AIYS) with negative Poisson’s ratio is designed and fabricated using a continuous, mass-producible, structure-programmable, and low-cost spinning technology. Based on the unique microfiber interlaced architecture, AIYS simultaneously achieves a Poisson’s ratio of-1.5, a robust mechanical property(0.6 c N/dtex), and a fast train-resistance responsiveness(0.025 s), which enhances conformality with the human body and quickly transduce human joint bending and/or stretching into electrical signals. Moreover, AIYS shows good flexibility, washability, weavability, and high repeatability. Furtherly, with the AIYS array, an ultrafast full-letter sign-language translation glove is developed using artificial neural network. The sign-language translation glove achieves an accuracy of 99.8% for all letters of the English alphabet within a short time of 0.25 s. Furthermore, owing to excellent full letter-recognition ability, real-time translation of daily dialogues and complex sentences is also demonstrated. The smart glove exhibits a remarkable potential in eliminating the communication barriers between signers and non-signers.展开更多
A theoretical analysis on the two extreme cases of yarn bending rigidity as well as the relationship between them is proposed. The significant influence of fiber-to-fiber interaction on yarn bending rigidity is reveal...A theoretical analysis on the two extreme cases of yarn bending rigidity as well as the relationship between them is proposed. The significant influence of fiber-to-fiber interaction on yarn bending rigidity is revealed.Experimental observation on the relationship between fabric/yarn bending property and fiber fineness, yarn structure, fabric structure is given as we ll. Three problems are discussed and the following conclusion is thus obtained. There exists, similar t0 a rigid engineering rod, a linear relationship between yarn bending rigidity and the square of yarn fineness (expressed as yarn count in tex), but the increasing speed is much lower. Yarn bending rigidity in the fabric also to a great extent depends on the fabric density and yarn twist factor, and so on. Fabric's bending hysteresis primarily depends on its bending rigidity.展开更多
基金National Natural Science Foundation of China(No.52273054)Shanghai Natural Science Foundation,China(No.20ZR1402200)。
文摘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.
基金National Natural Science Foundation of China(No.52275478)Fundamental Research Funds for the Central Universities,China(No.2232024Y-01)DHU Distinguished Young Professor Program,China(No.LZB2023001)。
文摘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.
文摘为解决Hadoop现有调度器调度任务时不能根据任务的紧迫程度分配资源的问题,研究YARN中的资源调度机制,改进原调度器(Capacity Scheduler),提出一种基于优先级权重的Hadoop YARN(Yet Another Resource Negotiator)调度算法(Weight Scheduler Based on Priority)。为叶子队列设置队列优先级,结合队列资源利用率和队列优先级选择队列;将应用程序的初始权重设置为应用程序优先级的大小,通过等待时间判断是否更新权重,根据权重对队列中的应用程序进行排序,调度时优先为权重高的应用程序分配资源。实验结果表明,与原有调度算法相比,改进算法平均任务执行时间约减少141 s,平均等待时间减少34.5%,保证了用户执行任务的相对公平,提高了用户总体满意度。
基金Key Project of Chinese Ministry of Education(No.108057)
文摘In this paper, the difference of the twist insertion levels of the compact and ring spun yarns of the same count is analyzed based on the relationship of the yarn twist factor to the twist angle and the bulk density. It is proposed that the relationship of the twist angle, twist level, and the yarn diameter should be synthetically considered when evaluating the twist insertion level of the compact yarn. The twist angle of the compact yarn is smaller than that of the ring yarn with the same twist insertion level. This results from the ordered fiber arrangement and compact structure of the compact yarn. Experiment was conducted to verify the conclusions. It is also discovered that the selection of the twist factor of the compact yarn, which can be usually lower than that of the ring yarn by 10%-15%, can be determined based on the yarn tensile strength.
基金supported by a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (NRF-2020R1A2C3003344 and NRF-2020R1A4A2002728)
文摘Yarn sensors have shown promising application prospects in wearable electronics owing to their shape adaptability, good flexibility, and weavability. However, it is still a critical challenge to develop simultaneously structure stable, fast response, body conformal, mechanical robust yarn sensor using full microfibers in an industrial-scalable manner. Herein, a full-fiber auxetic-interlaced yarn sensor(AIYS) with negative Poisson’s ratio is designed and fabricated using a continuous, mass-producible, structure-programmable, and low-cost spinning technology. Based on the unique microfiber interlaced architecture, AIYS simultaneously achieves a Poisson’s ratio of-1.5, a robust mechanical property(0.6 c N/dtex), and a fast train-resistance responsiveness(0.025 s), which enhances conformality with the human body and quickly transduce human joint bending and/or stretching into electrical signals. Moreover, AIYS shows good flexibility, washability, weavability, and high repeatability. Furtherly, with the AIYS array, an ultrafast full-letter sign-language translation glove is developed using artificial neural network. The sign-language translation glove achieves an accuracy of 99.8% for all letters of the English alphabet within a short time of 0.25 s. Furthermore, owing to excellent full letter-recognition ability, real-time translation of daily dialogues and complex sentences is also demonstrated. The smart glove exhibits a remarkable potential in eliminating the communication barriers between signers and non-signers.
文摘A theoretical analysis on the two extreme cases of yarn bending rigidity as well as the relationship between them is proposed. The significant influence of fiber-to-fiber interaction on yarn bending rigidity is revealed.Experimental observation on the relationship between fabric/yarn bending property and fiber fineness, yarn structure, fabric structure is given as we ll. Three problems are discussed and the following conclusion is thus obtained. There exists, similar t0 a rigid engineering rod, a linear relationship between yarn bending rigidity and the square of yarn fineness (expressed as yarn count in tex), but the increasing speed is much lower. Yarn bending rigidity in the fabric also to a great extent depends on the fabric density and yarn twist factor, and so on. Fabric's bending hysteresis primarily depends on its bending rigidity.
