A Cell-Based Smoothed Finite Element Method for Modal Analysis of Non-Woven Fabrics

The combination of a 4-node quadrilateral mixed interpolation of tensorial components element(MITC4)and the cell-based smoothed finite element method(CSFEM)was formulated and implemented in this work for the analysis of free vibration and unidirectional buckling of shell structures.This formulation was applied to numerous numerical examples of non-woven fabrics.As CSFEM schemes do not require coordinate transformation,spurious modes and numerical instabilities are prevented using bilinear quadrilateral element subdivided into two,three and four smoothing cells.An improvement of the original CSFEM formulation was made regarding the calculation of outward unit normal vectors,which allowed to remove the integral operator in the strain smoothing operation.This procedure conducted both to the simplification of the developed formulation and the reduction of computational cost.A wide range of values for the thickness-to-length ratio and edge boundary conditions were analysed.The developed numerical model proved to overcome the shear locking phenomenon with success,revealing both reduced implementation effort and computational cost in comparison to the conventional FEM approach.The cell-based strain smoothing technique used in this work yields accurate results and generally attains higher convergence rate in energy at low computational cost.

Beijing Dayuan Non-woven Fabric Co.Ltd

Situated in the Shilong Industrial District of Mentougou, Beijing, the Beijing Dayuan Non-woven Fabric Co. Ltd is a Sino-foreign joint venture producing non-woven fabrics, set up in 1991.

Preparation of UV-curable Nano-silver Antimicrobial Agent and Its Application in Non-woven Fabric

Nano-silver and waterborne polyurethane(WPU)composite emulsion was synthesized.The average diameter of silver nanoparticles(SNPs)was about 20 nm,and the average diameter of WPU was 101.32 nm.The anti-bacteria finishing of a polypropylene non-woven fabric(NWF)was carried out by ultraviolet finishing technology and the double dipping twin-roll method.The standard AATCC100 was used to test the antimicrobial activity of the samples.The results showed that the antimicrobial rates of Klebsiella pneumoniae(K.pneumoniae)and Staphylococcus aureus(S.aureus)were above 90%,which indicated that the NWF finishing had good antimicrobial activity.In addition,the thermal stability,mechanical properties,whiteness and contact angle of antimicrobial finishing nonwovens were characterized.The results showed that the performance of antimicrobial nonwovens was stable at 300℃.The breaking strength was better than that of untreated nonwovens,and the contact angle reached 119.1°.

Relationship between Light Scattering Intensity and Basis Weight of Non-Woven Fabrics

The relationship between light scattering intensity and basis weight of nonwoven fabrics is studied by using the theory of electromagnetic wave propagation and scatter-ing in random media.The theoretical analysis shows that the backscattering intensity of nonwoven fabric is closely related to its basis weight,and 2 series nonwoven samples manufactured by spun-bonded and thermal-bounded processing methods are tested for checking the theoretical expression.The study shows that the scattering intensity increases with increasing basis weight of nonwoven fabrics in exponential equation,and theoretical expression is consistent with the experimental data.

TiO_2/Polyester Non-woven Fabrics as a Kind of Photocatalyst for the Degradation of Formaldehyde Gas

The feasibility of photocatalytic degradation of the formaldehyde gas by titanium dioxide （TiO2）/polyester non-woven fabrics was studied. The effects of parameters such as the concentration of TiO2 solution, pH value, and drying temperature on the photocatalytic degradation of the formaldehyde gas were also studied. The results showed that the photodegradation efficiency of the formaldehyde gas increased rapidly with the increasing of the concentration of TiO2 solution up to 15g/L, but when the concentration was in excess of 15 g/L, the photodegradation efficiency decreased gradually and fluctuated due to light obstruction and disperse state of TiO2. Adjusting the pH value in the solution, the efficiency of photocatalytic degradation of the formaldehyde gas could be improved. The mechanisms of the reaction and the role of the additives were also investigated. After 42hours, TiO2/polyester non-woven fabric showed no significant loss of the photocatalytic activity.

Single-wall carbon nanotube fiber non-woven fabrics with a high electrothermal heating response

Carbon nanotube(CNT)fibers have great promise for constructing multifunctional fabrics with high electrical conductivity,good electro-heating ability,excellent flexibility,and a low density.However,the inter-fiber contacts in the fabric greatly reduce these advantages and limit their application.Herein,a simple pressure-fusing method to fabricate single-wall CNT(SWCNT)fiber non-woven fabrics(NWFs)that are composed of interconnected SWCNT fibers with fused joints is reported,which have good flexibility,a low density of 0.46 g/cm^(3),a high electrical conductivity of 3.7×10^(5)S/m,and a record high specific electrical conductivity of 803(S·m^(2))/kg.They also showed excellent electrical heating ability,so that a temperature of~160℃was rapidly reached at a low voltage of 2 V.Combined with their low density,the SWCNT fiber NWFs are promising for use as a heating unit for low temperature battery protection and de-icing applications.

基于Fabric的海量交易数据上链预处理机制

Hyperledger Fabric是一种国内外广泛使用的联盟链框架,在基于Fabric技术的一些业务中具有协同组织众多、交易操作频繁、事务冲突增加等特点。Fabric采用的多版本并发控制技术能够在一定程度上解决部分交易冲突,提升系统并发性,但其机制不完善,会出现部分交易数据无法正常上链存储的问题。为了实现海量交易数据完整、高效、可信的上链存储,提出一种基于Fabric预言机的数据上链预处理机制。设计海量数据冲突预处理(MCPP)方法,通过检测、监听、延时提交、事务加锁、重排序缓存等方式实现主键冲突交易数据的完整上链。引入数据传输保障措施,在传输过程中利用非对称加密技术防止恶意节点伪造认证信息,确保交易数据链外处理前后的一致性。通过理论分析和实验结果表明,该机制可有效解决联盟链平台中海量交易数据上链时的并发冲突问题,当交易数据规模达到1 000和10 000时,MCPP的时效性比LMLS提高了38%和21.4%,且成功率接近100%,具有高效性和安全性,同时在无并发冲突情况下不影响Fabric系统性能。

基于CP-ABE算法的Fabric隐私保护模型

传统区块链系统缺少对区块数据的隐私保护。结合CP-ABE(基于属性加密的密文策略)算法和IPFS(星际文件系统),提出一种可以对Fabric区块链实现访问控制的隐私保护模型CP-PPM。CP-PPM的数据所有者可以灵活设置访问控制策略。仿真结果表明,与现有Fabric区块链系统相比,CP-PPM模型支持细粒度的访问控制,具有更强的隐私保护效果;CP-ABE算法可以安全初始化,对数据的加解密效率更高,同时增强了区块链系统的存储性能。

Surface Morphology and Thermo-Electrical Energy Analysis of Polyaniline (PANI) Incorporated Cotton Fabric

With the exponential development in wearable electronics,a significant paradigm shift is observed from rigid electronics to flexible wearable devices.Polyaniline(PANI)is considered as a dominant material in this sector,as it is endowed with the optical properties of both metal and semiconductors.However,its widespread application got delineated because of its irregular rigid form,level of conductivity,and precise choice of solvents.Incorporating PANI in textile materials can generate promising functionality for wearable applications.This research work employed a straightforward in-situ chemical oxidative polymerization to synthesize PANI on Cotton fabric surfaces with varying dopant(HCl)concentrations.Pre-treatment using NaOH is implemented to improve the conductivity of the fabric surface by increasing the monomer absorption.This research explores the morphological and structural analysis employing SEM,FTIR and EDX.The surface resistivity was measured using a digital multimeter,and thermal stability is measured using TGA.Upon successful polymerization,a homogenous coating layer is observed.It is revealed that the simple pre-treatment technique significantly reduces the surface resistivity of Cotton fabric to 1.27 kΩ/cm with increasing acid concentration and thermal stability.The electro-thermal energy can also reach up to 38.2°C within 50 s with a deployed voltage of 15 V.The modified fabric is anticipated to be used in thermal regulation,supercapacitor,sensor,UV shielding,antimicrobial and other prospective functional applications.

Fabrication of Non-woven Fabric-Based SERS Substrate for Direct Detection of Pesticide Residues in Fruits

In surface-enhanced Raman scattering(SERS),flexible substrate plays an important role in target molecular collection from various shape surfaces and increases the analytical sensitivity.In this study,silver nanoparticles(Ag NPs)were deposited on a non-woven fabric used as an SERS substrate by self-assembly,in situ growing or the self-assembly/in situ growing combination method.4-Aminothiophenol was selected as a model molecular for the evaluation of the SERS performance using the substrates.The Ag NPs substrate prepared by self-assembly/in situ growing method presented the best Raman enhancement effect and its enhancement factor was estimated as high as 3.59106.The substrate was applied to the determination of four pesticide residues on the surfaces of fruit samples through wipe sampling,and the results revealed the good reproducibility of SERS responses and high detection sensitivity.The prepared flexible substrate was simple to fabricate and environmentally friendly.It could be expected to be a useful tool in rapid on-site test of pesticide residues on fruit surfaces because of its high sensitivity,convenience and non-destructive characteristics.

A new kind of resin-based wet friction material:Non-woven fabrics with isotropic fiber networks as preforms

As an alternative to short fibers,non-woven fabrics(NWFs)were made using different types of long fibers to optimize the performance of paper-based friction materials and their technology.In this investigation,the fillers and resin were impregnated into these NWFs to prepare three kinds of wet friction material.The tribological,mechanical,and thermal properties of the new wet friction material were studied.The results indicate that the dynamic friction coefficient of the new friction material is approximately 0.12 and the static friction coefficient is approximately 0.15;the better wear rate is 0.81334×10^(-14)m^(3)·(N·m)^(-1).In addition,the temperature for 10%mass loss yielded 100°C enhancement and the tensile strength was improved by 200%,compared to previously reported values.Most importantly,the advantages include a simple preparation flow,low cost,and resource conservation.This is a promising approach for the future development of paper-based friction materials.

Flexible and Reusable Non-woven Fabric Photodetector Based on Polypyrrole/Crystal Violate Lactone for NIR Light Detection and Writing

Rapid NIR light detection and/or writing has drawn much attention,but their practical applications have been limited by obtaining such NIR photodetectors.To address this problem,we have developed a simple and versatile strategy to prepare a non-woven fabric photodetector.The blue non-woven fabric photodetector has been prepared by coating photo-thermochromic ink(including crystal violet lactone(CVL)as the thermo-sensitive dye,polypyrrole(PPy)nanospheres as the photothermal component and hydroxyethyl cellulose(HEC)as the polymer matrix)on white non-woven fabric.When the blue fabric photodetector is irradiated by NIR(808-nm as model,0.75 W cm^(−2))laser,the discoloration occurs in 35 s,and higher laser intensity confers more rapid discoloration.This discoloration results from the photothermal effect of PPy which confers the elevation of temperature(>50℃)and then converts CVL to its leuco form(colorless).When the laser is turned off,the temperature drops to below the transition temperature(<43℃),and then CVL reverts to its initial blue color.Moreover,different figures and images can be easily printed on the fabric photodetector by 808 nm laser,and then they can be erased automatically under ambient conditions,with excellent cycling stability.Therefore,this fabric photodetector may act as a new platform for rapid NIR light detection and writing.

Comparative Study of Polypropylene Non-Woven Surgical Mask and Locally Manufactured Woven and Knitted Fabrics Facial Masks

The outbreak of coronavirus has led to an increase in the demand for facemasks globally. Unavailability of appropriate polypropylene non-woven fabrics face masks as a result of inadequate supply to satisfy the growing population has brought about the manufacturing of locally fabrics masks to augment or substitute standard medical class facemasks. The study aims at analyzing airflow of these locally manufactured fabrics to determine possible means of transmitting the virus as well as establish comfort of the user of these masks. Standard polypropylene non-woven, woven and knitted fabrics were considered for the study. Air permeability test was conducted on these fabrics using Frazier Air permeability tester. Depending on the property significant variation in the textile fabrics, polypropylene non-woven is widely accepted for facial masks. Nevertheless, this study illustrates that woven and knitted fabrics have more open structures, which allow a high rate of air penetration and so may require two or three layers to prevent antimicrobial or antiviral potential.

Composite polymer electrolyte membranes supported by non-woven fabrics for lithium-ion polymer batteries

Poly(vinylidene fluoride-co-hexafluoropropyle- ne) (PVDF-HFP) is one of the most popular polymers for polymer electrolyte membranes because of its excellent oper- ating characteristics and superior electrochemical properties. The electrochemical performances of polymer electrolyte membrane can be enhanced by evenly dispersing nano-meter SiO2 particles in the polymer. In this paper, non-woven fab- rics were immersed in the mixed solution of PVDF-HFP/ SiO2/butanone/butanol/plasticizer, and then dried in a vac- uum oven to remove the solvents and the plasticizer and to make porous composite polymer electrolyte membranes. The prepared composite membranes supported by non-woven fabrics boast good mechanical strength and excellent elec- trochemical properties: the electrochemical stability window is 4.8 V vs. Li+/Li, and the ionic conductivity is 3.35×10?4 S/cm (around 60% of that of a common PE membrane) at room temperature. The lithium-ion polymer battery assem- bled by the composite membrane exhibits high rate capabil- ity and excellent cycling performance.

基于区块链Fabric架构的个体学信系统设计

目前,个人学信数据的完整性和准确性难以达到用人单位的需求,教育机构的大量学习记录和成果被闲置。针对此问题,文章设计了基于区块链Fabric架构的个体学信系统。该系统由业务系统层、区块层、服务层、应用层组成,涉及学习者、用人单位、教育机构和颁证部门4个主体,通过授权的方式实现区块链交易和共识机制。

基于Hyperledger Fabric框架区块链基础平台安全沙箱机制研究

区块链基础平台基于Hyperledger Fabric框架开发,主要包括智能合约、客户端、共识机制等。数据以沙箱方式传输到数据需求方,智能合约会根据指定策略控制沙箱的访问权限和时效性,阅后即焚,保障数据提供方的数据所有权。区块链基础平台可实现数据使用可溯、可管,采用原数据目录上链的形式进行数据共享,以智能合约定义数据使用规则,数据使用记录上链,全程记录数据调用信息,确保数据安全、不可篡改,数据可信、可追踪。

面向Fabric的跨链可行性方法研究

随着区块链技术不断地发展,Fabric框架已成为目前最主流的联盟链框架。面对不同业务需求,区块链研发人员往往为不同的应用场景构建不同的区块链,这种单链架构的业务链面临业务复杂、吞吐率低、拓展难等风险,跨链技术能帮助简单业务链完成互操作从而实现复杂的业务功能。本文综合分析了目前主流跨链技术的优缺点,提出了基于中继链与跨链中间件的跨链模型,并在此模型下基于跨链协议、背书策略交易证明、跨链事务管理实现Fabric跨链智能合约互操作。经过实验与性能分析表明本文提出的方法是可行的。

基于键值状态分片的HyperLedger Fabric性能优化

HyperLedger Fabric是受关注度较高的开源联盟区块链.针对现有区块链分片方法不适用于Fabric三阶段交易模型的问题和分片粒度过粗导致存在热点访问的问题,提出一种基于Fabric实现的细粒度键值状态分片方法.首先,详细设计了Fabric在键值状态分片下的跨片交易处理,引入跨分片排序节点和两阶段提交处理流程,高效保证跨片交易的一致性和原子性.然后,针对细粒度分片可能导致交易跨片概率上升进而影响性能的问题,提出启发式的交易提案路由表,旨在减少预执行阶段交易的跨片读数据请求,降低计算资源和网络资源的消耗.最后,在Fabric仿真系统上实现改进的分片方案并进行性能测试.实验结果表明,该方法在提升Fabric性能的基础上,有效解决了热点访问问题和高跨片交易占比下的性能下降问题.

基于Hyperledger Fabric与星际文件系统相结合的数据存储框架

利用Hyperledger Fabric和星际文件系统设计了一种新的数据存储框架,使用Hyperledger Fabric的Level DB保存规模较小的状态数据,利用星际文件系统保存账本中大规模的交易数据,并改造了原来的数据存储和数据查询模块。新框架有效扩展了Hyperledger Fabric的存储能力,缓解了记账节点的数据膨胀问题。实验结果表明,新框架在保证安全性的前提下,增加了部分网络延迟,但相对于区块链存储的可扩展性而言,这个代价是可以接受的。

Solvent engineering towards scalable fabrication of high-quality perovskite films for efficient solar modules

Over the last decade,remarkable progress has been made in metal halide perovskite solar cells(PSCs),which have been a focus of emerging photovoltaic techniques and show great potential for commercialization.However,the upscaling of small-area PSCs to large-area solar modules to meet the demands of practical applications remains a significant challenge.The scalable production of high-quality perovskite films by a simple,reproducible process is crucial for resolving this issue.Furthermore,the crystallization behavior in the solution-processed fabrication of perovskite films can be strongly influenced by the physicochemical properties of the precursor inks,which are significantly affected by the employed solvents and their interactions with the solutes.Thus,a comprehensive understanding of solvent engineering for fabricating perovskite films over large areas is urgently required.In this paper,we first analyze the role of solvents in the solution-processed fabrication of large-area perovskite films based on the classical crystal nucleation and growth mechanism.Recent efforts in solvent engineering to improve the quality of perovskite films for solar modules are discussed.Finally,the basic principles and future challenges of solvent system design for scalable fabrication of high-quality perovskite films for efficient solar modules are proposed.