A minicomputer-controlled all-digital tensile test system

This paper presents the design, construction, and evaluation of an all-digital programmable tensile test system, superior in several ways to other systems presently available for testing yarns. However, the basic system concepts can be applied to tensile test systems for other materials. The system is capable of performing three standard yarn tests: constant rate of extension, constant rate of loading, and fatigue. Extension rates range from 1 mm/s to 420 mm/s. Loading rates of up to 700 g/s and above are possible. Fatigue testing allows sinusoidal loading of yarn at frequencies from 0.88 to 5.2 Hz. A minicomputer is used for direct digital control, data acquisition, and on-line analysis. A digital tension mechanism incorporating a variable-reluctance step motor was designed and constructed. A "fractional stepping" scheme is presented where the computer software is used to improve the displacement resolution for slow-speed breaks. A unique indirect digital force transducer was designed for the system employing transistor-transistor logic integrated circuits. The interrogation rate is 7 kHz, the load range is 0-700 g, and resolution for the present design is 4 g. Final testing of the digital system involves the comparison of test results with those from a proved programmable analog tester. The three types of tests produced good results and show that the digital test system does characterize yarn break strength for different types of yarn. It overcomes many disadvantages of analog systems and performs certain tasks which these systems are unable to perform.     

Highly Conductive Carbon Nanotube‐Graphene Hybrid Yarn

An efficient procedure for the fabrication of highly conductive carbon nanotube/graphene hybrid yarns has been developed. To start, arrays of vertically aligned multi‐walled carbon nanotubes (MWNT) are converted into indefinitely long MWNT sheets by drawing. Graphene flakes are then deposited onto the MWNT sheets by electrospinning to form a composite structure that is transformed into yarn filaments by twisting. The process is scalable for yarn fabrication on an industrial scale. Prepared materials are characterized by electron microscopy, electrical, mechanical, and electrochemical measurements. It is found that the electrical conductivity of the composite MWNT‐graphene yarns is over 900 S/cm. This value is 400% and 1250% higher than electrical conductivity of pristine MWNT yarns or graphene paper, respectively. The increase in conductivity is asssociated with the increase of the density of states near the Fermi level by a factor of 100 and a decrease in the hopping distance by an order of magnitude induced by grapene flakes. It is found also that the MWNT‐graphene yarn has a strong electrochemical response with specific capacitance in excess of 111 Fg^?1. This value is 425% higher than the capacitance of pristine MWNT yarn. Such substantial improvements of key properties of the hybrid material can be associated with the synergy of MWNT and graphene layers in the yarn structure. Prepared hybrid yarns can benefit such applications as high‐performance supercapacitors, batteries, high current capable cables, and artificial muscles.     

Fast and High-Strain Electrochemically Driven Yarn Actuators in Twisted and Coiled Configurations

Commercially available yarns are promising precursor for artificial muscles for smart fabric-based textile wearables. Electrochemically driven conductive polymer (CP) coated yarns have already shown their potential to be used in smart fabrics. Unfortunately, the practical application of these yarns is still hindered due to their slow ion exchange properties and low strain. Here, a method is demonstrated to morph poly-3,4-ethylenedioxythiophene:poly-styrenesulfonate (PEDOT:PSS) coated multifilament textile yarns in highly twisted and coiled structures, providing > 1% linear actuation in < 1 s at a potential of + 0.6 V. A potential window of + 0.6 V and –1.2 V triggers the fully reversible actuation of a coiled yarn providing > 1.62% strain. Compared to the untwisted, regular yarns, the twisted and coiled yarns produce > 9 ×  and > 20 ×  higher strain, respectively. The strain and speed are significantly higher than the maximum reported results from other electrochemically operated CP yarns. The yarn's actuation is explained by reversible oxidation/reduction reactions occurring at CPs. However, the helical opening/closing of the twisted or coiled yarns due to the torsional yarn untwisting/retwisting assists the rapid and large linear actuation. These PEDOT:PSS coated yarn actuators are of great interest to drive smart textile exoskeletons.     

基于红外传感器的环锭纺断纱在线检测装置

为了解决环锭纺纱在纺纱过程中细纱断头难以及时发现的问题,提高纺织企业的生产效能,设计了基于红外传感器的环锭纺断纱在线检测装置,装置包括红外传感器、双运算放大器和单片机控制模块。在环锭细纱机上试纺18.2 tex棉纱,利用环锭纺断纱检测装置对纺纱过程中的细纱气圈信号进行在线检测。实验结果表明,装置将细纱气圈信号转换成电信号,再经过单片机控制模块处理判断,准确实现了细纱断纱在线检测。为了验证装置对棉纱的品种适应性,对5.8 tex、9.7 tex、18.2 tex三种纱支的棉纱进行检测。结果表明,装置能够实现对市场上大部分棉纱的断纱在线检测。     

Niobium Nanowire Yarns and their Application as Artificial Muscles

Metal nanowires are twisted to form yarns that are strong (0.4 to 1.1 GPa), pliable, and more conductive (3 × 10⁶ S m^?1) than carbon nanotube yarns. Niobium nanowire fibers are extracted by etching a copper‐niobium nano‐composite material fabricated using the severe plastic deformation process. When impregnated with paraffin wax, the niobium (Nb) nanowire yarns produce fast rotational actuation as the wax is heated. The heated wax expands, untwisting the yarn, which then re‐twists upon cooling. Normalized to yarn length, 12 deg mm^?1 of torsional rotation was achieved along with twist rates in excess of 1800 rpm. Tensile modulus of 19 ± 5 GPa was measured for the Nb yarns, which is very similar to those of carbon multiwalled nanotubes.     

Knittable and Washable Multifunctional MXene‐Coated Cellulose Yarns

Textile‐based electronics enable the next generation of wearable devices, which have the potential to transform the architecture of consumer electronics. Highly conductive yarns that can be manufactured using industrial‐scale processing and be washed like everyday yarns are needed to fulfill the promise and rapid growth of the smart textile industry. By coating cellulose yarns with Ti₃C₂T_x MXene, highly conductive and electroactive yarns are produced, which can be knitted into textiles using an industrial knitting machine. It is shown that yarns with MXene loading of ≈77 wt% (≈2.2 mg cm^?1) have conductivity of up to 440 S cm^?1. After washing for 45 cycles at temperatures ranging from 30 to 80 °C, MXene‐coated cotton yarns exhibit a minimal increase in resistance while maintaining constant MXene loading. The MXene‐coated cotton yarn electrode offers a specific capacitance of 759.5 mF cm^?1 at 2 mV s^?1. A fully knitted textile‐based capacitive pressure sensor is also prepared, which offers high sensitivity (gauge factor of ≈6.02), wide sensing range of up to ≈20% compression, and excellent cycling stability (2000 cycles at ≈14% compression strain). This work provides new and practical insights toward the development of platform technology that can integrate MXene in cellulose‐based yarns for textile‐based devices.     

Full‐Textile Wireless Flexible Humidity Sensor for Human Physiological Monitoring

Textile‐based electronic techniques that can in real‐time and noncontact detect the respiration rate and respiratory arrest are highly desired for human health monitoring. Yarn‐shaped humidity sensor is fabricated based on a sensitive fiber with relatively high specific surface area and abnormal cross‐section. The response and recovery time of the yarn‐shaped humidity sensor is only 3.5 and 4 s, respectively, with little hysteresis, because of the hydrophobic property of these functional fibers and the grooves on the surface of the fibers, which is much faster than those of the commercial polyimide materials. Moreover, a battery‐free LC wireless testing system combined with the yarn‐shaped sensor is fabricated, which is further successfully imbedded into the intelligent mask to detect human breath. Based on the detection of LC wireless testing system, the frequency of 50.25 MHz under the exhaled condition shifts to 50.86 MHz under the inhaled situation of humidity sensor. In essence, the functional yarns with proper structure, would be an excellent candidature to the yarn‐shaped humidity sensor, in which there are good performance and wide application possibilities, eventually offering a facile method for the wireless detection of human physiological signals in the field of electronic fabrics.     

融合空间模糊C-均值聚类的纱线疵点检测算法

为了精确评价纱线疵点的种类与个数,提出了一种融合空间模糊C-均值(FCM)聚类的纱线疵点检测算法。首先利用融合空间FCM聚类算法提取纱线条干;然后对纱线条干进行形态学开运算处理,以获取精确的纱线条干,并利用条干上下边缘点之间的像素个数计算纱线的直径与平均直径;最后根据纱线疵点标准判定纱线疵点的种类与个数。为了验证本算法的有效性和准确性,对多种不同线密度的纯棉纱线进行测试,并将测试结果与电容性纱疵分级仪的检测结果进行对比。结果表明,本算法与电容性的检测结果一致性较好,且价格低廉,不易受环境温度、湿度等因素的影响。     

High‐Energy Asymmetric Supercapacitor Yarns for Self‐Charging Power Textiles

Rapid growth of electronic textile increases the demand for textile‐based power sources, which should have comparable lightweight, flexibility, and comfort. In this work, a self‐charging power textile interwoven by all‐yarn‐based energy‐harvesting triboelectric nanogenerators (TENG) and energy‐storing yarn‐type asymmetric supercapacitors (Y‐ASC) is reported. Common polyester yarns with conformal Ni/Cu coating are utilized as 1D current collectors in Y‐ASCs and electrodes in TENGs. The solid‐state Y‐ASC achieves high areal energy density (≈78.1 µWh cm^?2), high power density (14 mW cm^?2), stable cycling performance (82.7% for 5000 cycles), and excellent flexibility (1000 cycles bending for 180°). The TENG yarn can be woven into common fabrics with desired stylish designs to harvest energy from human daily motions at high output (≈60 V open‐circuit voltage and ≈3 µA short‐circuit current). The integrated self‐charging power textile is demonstrated to power an electronic watch without extra recharging by other power sources, suggesting its promising applications in electronic textiles and wearable electronics.     

BRT-MOM-ILDC方法分析海上无人机群目标全极化散射特性

随着海面低慢小群目标威胁性的不断增强,其雷达回波的有效探测受到了世界各国的广泛重视。海杂波影响分析和对目标上精细结构建模这两个问题是海上低慢小目标雷达散射特性仿真研究的重点内容,因此,本文以海上无人机群为分析目标,针对其飞行高度低、受杂波影响大、局部结构反射截面积小的目标特性,综合采用高频双向射线追踪方法（BRT）、多层快速多极子加速的矩量法（MOM）和边缘区域的增量长度绕射理论方法（ILDC）分区域实现可靠的电磁散射建模。该方法将目标区域分为高频电大区域、低频精细区域和棱边区域进行理论分析与计算,采用多路径方法对目标间、目标与海面的耦合作用进行有效的补充,实现全极化海面目标的散射特性高效计算和快速成像。结果分析表明,采用本文方法可以快速的获取全极化的目标散射回波和雷达图像,从而为目标识别提供大量样本信息。      

Wearable Energy Generating and Storing Textile Based on Carbon Nanotube Yarns

The challenges of textiles that can generate and store energy simultaneously for wearable devices are to fabricate yarns that generate electrical energy when stretched, yarns that store this electrical energy, and textile geometries that facilitate these functions. To address these challenges, this research incorporates highly stretchable electrochemical yarn harvesters, where available mechanical strains are large and electrochemical energy storing yarns are achieved by weaving. The solid‐state yarn harvester provides a peak power of 5.3 W kg^?1 for carbon nanotubes. The solid‐state yarn supercapacitor provides stable performance when dynamically deformed by bending and stretching, for example. A textile configuration that consists of harvesters, supercapacitors, and a Schottky diode is produced and stores as much electrical energy as is needed by a serial or parallel connection of the harvesters or supercapacitors. This textile can be applied as a power source for health care devices or other wearable devices and be self‐powered sensors for detecting human motion.     

Carbon‐Nanotube‐Templated,Sputter‐Deposited,Flexible Superconducting NbN Nanowire Yarns

Flexible superconducting yarns consisting of sputter‐deposited NbN nanowires on highly aligned carbon nanotube (CNT) array sheets are reported. In the microscopic view, the NbN nanowires are formed on top of individual CNT fibrils, and the superconductivity property of the twist‐spun NbN–CNT yarn system is comparable to that of a typical NbN thin film on a normal solid substrate. Because of its intrinsic porosity, the system exhibits superior mechanical flexibility with a small bending radius. It also remains a superconducting state even when subjected to severe mechanical deformations, primarily due to the proximity superconductivity through carbon nanotube bundles. The results demonstrate the possibility of fabricating flexible superconducting yarns in a conventional thin‐film deposition process, using ultraflexible free‐standing CNT sheets as a template. In addition, preliminary tests on reducing the normal‐state resistance toward superconducting cable applications are presented.     

Beyond capacitive systems with optical measurements for yarn evenness evaluation

Yarn evenness is usually obtained with capacitive systems evaluating mass per unit length variations. More recently, optical sensors have been proposed. In this paper, we present experimental results of yarn evenness evaluation with an optical measuring system, sensitive to the light absorbed and diffused by a moving yarn. Results obtained with the optical sensor are compared with measurements performed by means of a capacitive commercial tester. Good agreement in measured count variation CV is obtained.

Moreover, optical and capacitive measurements, simultaneously done on the same thread, allow to obtain a reliable comparison between the two measurement methods, in particular for what concerns yarn signal spectrograms.     

Catalytic Twist‐Spun Yarns of Nitrogen‐Doped Carbon Nanotubes

The treatment of free‐standing sheets of multiwalled carbon nanotubes (MWNTs) with a NH₃/He plasma results in self‐supporting sheets of aligned N‐doped MWNTs (CN_x). These CN_x sheets can be easily twist spun in the solid state to provide strong CN_x yarns that are knottable, weavable, and sewable. The CN_x yarns exhibit tunable catalytic activity for electrochemically driven oxygen reduction reactions (ORR), as well as specific capacitances (up to 39 F·g^?1) that are 2.6 times higher than for the parent MWNTs. Due to a high degree of nanotube alignment, the CN_x yarns exhibit specific strengths (451 ± 61 MPa·cm³·g^?1) that are three times larger than observed for hybrid CN_x/MWNT biscrolled yarns containing 70 wt.% CN_x in the form of a powder. This difference in mechanical strength arises from substantial differences in yarn morphology, revealed by electron microscopy imaging of yarn cross‐ sections, as well as the absence of a significant strength contribution from CN_x nanotubes in the biscrolled yarns. Finally, the chemical nature and abundance of the incorporated nitrogen within the CN_x nanotubes is studied as function of plasma exposure and annealing processes using X‐ray photoelectron spectroscopy and correlated with catalytic activity.     

The Characterization of Conductive Textile Materials Intended for Radio Frequency Applications

Antennas constructed in part from conductive textile materials (also known as e-textiles) by means of standard textile manufacturing techniques are currently receiving increasing attention from antenna theorists and antenna manufacturers alike. However, due mostly to the unique fabrication methods employed, these novel materials cannot be treated as simple, equivalent substitutes for the more-conventional metallic antennas. Conductive yarns can have considerably less-than-ideal conductivity, and their inhomogeneous internal structure, with features small with respect to the skin depth, can be difficult to analyze directly in terms of conductive-material bulk resistivity. Furthermore, the undulating and sometimes non-planar nature of stitched or woven conductive textile yarns introduces a significant phase delay that must be properly taken into account. This article describes a method to determine the conductivity, sigma , which accurately represents a lossy inhomogeneous textile conductor for a MoM segment having the same radius as the actual conductive yarn. This method has three steps. First, the resistance per unit length of the textile conductor is determined experimentally, in a transmission-line test cell. Next, this measured resistance per unit length is adjusted to account for the nonuniform current distribution across the multiple yarn conductors. Finally, a surface-impedance formulation is employed to derive an equivalent MoM-segment bulk conductivity that accurately represents the measured conductor's performance. Excess phase delay, inherent in textile conductors, is determined by examination of the phase component of the test cell scattering parameter, S₂₁.     

基于C P L D技术的码位交织与反交织系统

介绍了数字通信中交织码编码的基本原则,提出了码位交织与反交织系统的实现方案,并用CPLD对系统电路进行了设计集成,仿真结果表明该系统工作稳定,并具有可扩展的灵活性。     

基于FPGA的高速DSP与液晶模块接口的实现

介绍了一种基于TMS320VC5402 DSP＆FPGA在液晶模块中的设计。针对高速DSP与LCD读写数据过程中时序的不匹配,提出了一种基于FPGA的解决方法。给出了快速器件DSP和慢速器件液晶模块的接口方法,并做出了逻辑时序分析；介绍了TMS320VC5402 DSP与液晶模块通过FPGA接口的硬件和软件实例,并给出了部分程序代码。利用FPGA进行I/O口的扩展,克服了DSP I/O口功能弱的缺点,提高了DSP的控制能力,节省了DSP的I/O资源。实验表明,该系统具有可靠性高的优点。     

Endurance behavior of conductive yarns

Various companies are industrializing ‘photonic’ textiles for medical and architectural applications. Here we report reliability testing of photonic textiles based on woven textiles with integrated copper-based conductive yarns used to drive attached LEDs. These textiles were subjected to cyclic mechanical stress tests and the cycle life was analyzed in terms of fatigue. Results show that failure is due to wire fractures at the transition from the rigid component to the compliant textile. The results are in good agreement with Cu-fatigue data from literature. This shows that it is possible to estimate the lifetime of electronic textiles under use conditions by the mechanical fatigue of the conducting yarn material properties.     

Improvements of Television Picture Quality by Eliminating the Disturbances Caused by Interlaced Scanning

Interlaced scanning is an effective technique to transmit pictures, but it causes an inherent disturbance in interlaced scanning (interlace disturbance) and deteriorates the picture quality. Recent developments of television signals and picture monitors have increased the interlace disturbance. A dual-beam display method which does not produce the interlace disturbance was constructed. By this apparatus, the effect of interlace disturbance and a tradeoff problem of the picture quality were tested. The results are as follows. 1) When the interlace disturbance is eliminated, the still picture quality is greatly improved. The higher the quality of the input signal, the greater the improvement of the picture quality. 2) The conspicuous scene strongly affects the overall picture quality in spite of the small probability of occurrence.     

光缆用膨胀阻水纱

简要介绍了光缆用膨胀阻水纱的阻水原理、性能及在光缆中的使用方法。与传统填充材料相比，膨胀阻水纱具有施工简单、性能可靠、较高的性价比和使用方便等优点。而且使用该材料填充的光缆具有自重轻、性能可靠、成本较低的优点。