Optimization of the Pretreatment of the Mixture of Cassava Peelings and Pineapple Fibers Using Response Surface Methodology and a Process Simulator for the Bioethanol Production

The increase in oil prices and greenhouse gas emissions has led to the search for substitutes for fossil fuels. In Cameroon, the abundance of lignocellulosic resources is inherent to agricultural activity. Production of bioethanol remains a challenge given the crystallinity of cellulose and the presence of the complex. The pretreatment aimed to solubilize the lignin fraction and to make cellulose more accessible to the hydrolytic enzymes, was done using the organosolv process. A mathematical modeling was performed to point out the effect of the temperature on the kinetics of the release of the reducing sugars during the pretreatment. Two mathematical model was used, SAEMAN’s model and Response surface methodology. The first show that the kinetic parameters of the hydrolysis of the cellulose and reducing sugar are: 0.05089 min-1, 5358.1461 J·mol-1, 1383.03691 min-1, 51577.6100 J·mol-1 respectively. The second model was used. Temperature is the factor having the most positive influence whereas, ethanol concentration is not an essential factor. To release the maximum, an organosolv pre-treatment of this sub-strate should be carried out at 209.08°C for 47.60 min with an ethanol-water ratio of 24.02%. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure.

IGA Based Bi-Layer Fiber Angle Optimization Method for Variable Stiffness Composites

This paper presents a topology optimization method for variable stiffness composite panels with varying fiber orientation and curvilinear fiber path.Non-uniform rational B-Splines(NURBS)based Isogeometric analysis(IGA)is utilized for the numerical computation of the general minimum compliance problem.The sensitivity analysis of the structure compliance function for the density and bi-layer orientation is conducted.The bi-layer fiber paths in the design domain are generated using streamline method and updated by divided pieces reselection method after the optimization process.Several common examples are tested to demonstrate the effectiveness of the method.The results show that the proposed method can generate more manufacturable fiber paths than some typical topology optimization methods.

The Optimization of Radio over Fiber Link by Proper Link Gain Control

we demonstrate the adjustability of optimal input power(OIP) of the radio over fiber(RoF) link by proper link gain control in the central unit(CU) and remote antenna unit(RAU).The experiment results show that the reading and writing distance(RWD)of the radio frequency identification(RFID)service and the throughput of the WiFi service have a max increase of 3cm and 6.975Mbit/s respectively when the OIP value equals to output power of commercial products,compared with OIP value with 5-dBm right/left shift to the output power.

The Technology Parameters Optimization of Extracting Natural Cellulose Fibers from Eulaliopsis Binata

The extracting process and parameters optimization of Eulaliopsis binata fibers were studied.The components of Eulaliopsis binata were tested,the cellulose contents was about 45%,and the lignin content was as high as 18.5%.And the components of Eulaliopsis binata fibers were compared with some bast fibers.The analysis of physical and chemical properties related to acid,alkali,and auxiliary agent about cellulose and pectin,and lignin components in Eulaliopsis binata fibers were investigated.The chemical processing was employed to extract Eulaliopsis binata fibers in which NaOH as cooking agent and Na5P3O10 as auxiliary agent.The universal rotatable composite experiment design was used to get the highly precise regression equations,in which the NaOH concentration,the auxiliary agent Na5P3O10 concentration and the processing time were the main technological parameters.The residual gum content,fiber fineness,fiber strength,and fiber length of Eulaliopsis binata were the evaluation indexes.Based on the relation among parameters of extracting process,degumming effect and quality indexs of Eulaliopsis binata fibers,the optimum parameters of extracting process on Eulaliopsis binata fibers can be obtained.The fibers extracted from Eulaliopsis binata can be developed as one kind of natural cellulose fibers suitable for producing various textile products.

Retro-Reflective Fiber Optic Displacement Sensor for Performance Optimization Using Taguchi Method

Fiber optic displacement sensors are widely used in industry. Retro reflective fiber optic displacement sensor consists of parallel fibers with a reflector at a distance. Light is launched into the transmitting fiber which gets reflected by reflector. This reflected light is collected by the receiving fiber. The received light is function of the displacement of the reflector from the fiber end faces. This paper is targeted to obtain a robust design for the fiber optic displacement sensor (FODS) using well known Taguchi method. The design takes care of all noise parameters within constraints of manufacturing tolerances. The statistical data analysis is performed on the simulated results. The larger the better signal to noise quality characteristics is used to find the effect of control parameters in the data analysis. Taguchi analysis suggests dominant parameters, which affects the sensitivity of the FODS and causes immunity to noise. A source fiber inclination angle is chosen as an adjustment parameter. Other control parameters are used for fine tuning of the FODS design for achieving three qualities viz. best robustness, optimized sensitivity and robustness and best sensitivity.

玄武岩-聚乙烯醇纤维对再生混凝土抗冻性能的影响

为了推广再生混凝土在高海拔和北方寒冷地区的应用,对单掺、混掺不同体积掺量玄武岩纤维和聚乙烯醇纤维的再生混凝土进行质量损失率、相对动弹性模量、抗压强度损失率3项抗冻性能指标的探究,并用SEM对200次冻融循环后混掺纤维再生混凝土进行细观作用机理分析,最后结合响应面法对混掺纤维掺量进行优选。结果显示:外掺纤维能够提高再生混凝土的抗冻性能,而混掺纤维效果优于单掺纤维;2种纤维在试件内部呈网状分布,协同受力,与基体互相约束,很大程度限制了裂缝的扩展和数量;纤维优化结果显示当聚乙烯醇纤维与玄武岩体积掺量分别为0.170%和0.246%时,再生混凝土的抗冻性能最优。研究成果对玄武岩-聚乙烯醇纤维再生混凝土纤维掺量设计具有一定的借鉴意义。

Optimizing the Glass Fiber Cutting Process Using the Taguchi Methods and Grey Relational Analysis

This paper mainly describes a new approach to optimizing of the cutting glass fiber with multiple performance characteristics, based on reliability analysis, Taguchi and Grey methods. During the cutting process, the speed, the volume and the cutting load are optimized cutting parameters when the performance characteristics, which include Weibull modulus and blade wear, are taken into consideration. In this paper, optimization with multiple performance characteristics is found to be the highest cutting speed and the smallest cutting volume, and the medium cutting load. An analysis of the variance of the blade wear indicates that the cutting speed (47.21%), the cutting volume (14.62%) and the cutting load (12.20%) are the most significant parameters in the cutting process of glass fibers. In summary, the most optimal cutting parameter should be A3B1C2. The results of experiments have shown that the multiple performance characteristics of cutting glass fiber are improved effectively through this approach.

柚子皮不溶性膳食纤维的提取工艺优化及特性分析

为获得复合酶法制备柚子皮不溶性膳食纤维的制备工艺及其吸附特性,实验以柚子皮为原料,采用正交试验优化提取柚子皮不溶性膳食纤维(IDF),并对其特性进行研究。结果表明,料液比1:40 g/mL、淀粉酶的添加量0.6%、淀粉酶的酶解时间90 min、木瓜蛋白酶的添加量0.2%、木瓜蛋白酶的酶解时间30 min为最佳提取条件,该条件下柚子皮IDF得率为55.07%。柚子皮IDF的膨胀力、持水力、持油力和阳离子交换能力分别为2.84±0.09 mL/g、12.54±0.11 g/g、1.54±0.02 g/g和0.36±0.04 mmol/g。此外,体外吸附研究表明,柚子皮IDF对葡萄糖、胆固醇、胆酸钠的吸附能力分别为0.13±0.003 mmol/g、12.27±0.020 mg/g和53.25±0.100 mg/g。FT-IR分析表明,柚子皮IDF具有纤维素类多糖的特征吸收峰,符合膳食纤维的结构。综上,优化工艺后提取的柚子皮IDF具有较好的特性,这为进一步开发利用柚子皮IDF提供了理论依据。

Polarization-Dependent Optimization of Fiber-Coupled Terahertz Time-Domain Spectroscopy System

The optimization of the fiber-coupled terahertz time-domain spectroscopy（THz-TDS） system is performed by changing the polarization of the optical excitation pulse centered at 1550 nm. In Ga As/In Al As multilayer structures based photoconductive antennas are used in TDS setup as both the emitter and receiver. The experimental results demonstrate that not only the THz signal power but also the temporal waveform vary with the rotation of the exciting pulse polarization. Maximum output power of the emitter is obtained when the polarization of the pump pulse is perpendicular to the edge of the metal electrodes. At this moment the THz waveform is close to a single-cycled pulse. However, double THz pulses could be recorded when the pump laser polarization is parallel to the electrodes. Laser pulse splitting induced by the birefringence of the optical fiber may attribute to the polarizationdependent performance of the fiber-coupled THz-TDS system.

高速动车组横梁应变场光纤测量与反演研究

针对高速动车组车底底架横梁的应变场反演问题,基于模态叠加法和传感器优化配置理论,提出一种根据部分测点的实测单向应变反演结构空间应变场的方法。以结构的应变模态为输入,以模态坐标独立性为目标,基于信息熵理论建立了传感器优化配置的数学模型,再根据模态坐标和振型采用正则化方法反演结构应变场。仿真计算结果表明,无噪声干扰下,反演的精度较高,最大均方误差为9.87×10~(-12),并且正则化方法可以有效抑制噪声对结果的影响。搭建了基于光纤光栅传感系统的测试试验台,基于实测应变数据和模态结果反演应变场,结果表明,反演后的应变幅值相对误差带为1.21%~10.79%,反演数据和实测数据的均方误差带为0.80~3.69。该方法能够准确识别结构的模态坐标,为获取高速列车关键结构的应变场分布提供参考。

IPRAN网络下5G时间同步优化方案研究

针对5G基站采用GPS同步方式时成本高、安全性低等问题,提出一系列的解决方案。首先,用双模模块解决卫星授时的安全性问题。其次,采用有源功率分配和无源功率分配方案解决卫星天线安装受限问题,并降低建设成本。在无法安装卫星天线的情况下,采用1588v2技术在IPRAN接入环内部署主从时钟源。该方案可以满足100 ns的同步精度需求,并且可以大幅度降低5G时间同步的部署成本,对5G时间同步技术的优化和部署有一定的借鉴作用。

基于响应面法的PP-PAM复合改良微生物固化膨胀土优化研究

【目的】采用微生物诱导碳酸钙沉淀技术(MICP)加固膨胀土,可有效提高膨胀土的强度,降低胀缩性,但存在土体破坏时脆性明显,以及养护初期崩解量高等问题,为了进一步改善微生物固化膨胀土的脆性破坏和养护初期崩解量高的问题,【方法】在微生物固化膨胀土的基础上,研究掺入聚丙烯纤维(PP)和聚丙烯酰胺(PAM)对微生物固化膨胀土破坏模式和水稳性的影响。以纤维长度、纤维掺量和聚丙烯酰胺掺量为影响因素,以无侧限抗压强度和崩解量为响应值,采用Box-Behnken响应面法进行条件优化试验,建立了响应面回归模型,获得聚丙烯纤维长度、聚丙烯纤维和聚丙烯酰胺用量及其交互作用对微生物固化膨胀土强度和崩解性综合指标的影响。【结果】结果表明:聚丙烯纤维的掺入降低了微生物固化膨胀土破坏时的脆性、提高了土体强度、降低了膨胀土的崩解性,但随着纤维长度的增加,崩解量逐渐增加;聚丙烯酰胺的掺入降低了膨胀土的崩解量,但会降低土体强度。【结论】在影响因素试验范围内,以无侧限抗压强度最高和崩解量最低为原则,通过Box-Behnken响应面法获得最佳配比为:聚丙烯纤维长度为9 mm,掺量为0.5%,聚丙烯酰胺掺量为0.12%。在此配比下,复合固化土的无侧限抗压强度为1.24 MPa,相比优化前提高了29.57%,崩解量仅为0.34%,相比优化前降低了99.07%。

丝/Optim纤维混纺织物风格的统计分析

采用绢丝作为经纱,羊毛、羊绒、绢丝、羊毛/绢丝、羊绒/Optim纤维、Optim纤维/绢丝/羊毛、Optim纤维/绢丝/羊绒混纺纱线作为纬纱,试制了具有丝绒、丝毛风格特性的一系列样品,采用FAST织物风格仪等测试触觉风格和视觉风格的性能指标。运用多元线性回归、方差分析和聚类分析等方法对测试结果进行了统计分析,探讨了织物中绢丝、羊绒、Optim纤维及羊毛含量与织物风格特性之间的关系。结果表明,Optim纤维含量对织物厚度、织物经纬向弯曲长度、织物悬垂性等均有较大的影响,Optim纤维能在一定范围内代替羊绒而不影响丝绒类织物的风格。

连续芳纶纤维增强PLA复合材料3D打印技术成型缺陷及工艺优化方法研究

连续纤维3D打印技术结合了复合材料高力学性能和3D打印灵活制造的优点,具有较大发展潜力。然而现有工艺制得的零件存在较多成型缺陷,影响了该技术的大规模应用。本文基于自行研制的3D打印设备制造芳纶纤维增强PLA试验件,研究试验件成型质量并提出了滑移缺陷发生条件,系统研究了纤维束滑移、剥离、断裂和层间孔隙等缺陷,最后提出优化打印速度、路径变化角、冷却系统和喷嘴外形四种工艺优化方法,设计了相关试验进行验证。结果表明,优化打印速度、路径变化角和增设冷却系统可将纤维束滑移距离分别降低45%、81%和50%,优化喷嘴设计可将纤维束断裂率降低90%。本研究为基于3D打印的复合材料设计和制造提供了新的思路和解决方案。

玻纤增强尼龙复合材料车门拉手座热流道模具设计

在车门拉手座塑件模具设计中,为解决高含量玻璃纤维增强尼龙复合材料成型时容易出现浮纤、收缩各向异性带来的翘曲变形大等潜在品质缺陷问题,运用CAE辅助分析对塑件的成型方案进行了优化分析。将浇注系统优化为潜伏式双浇口浇注系统,浇口的进胶直径为1 mm,流道结构由三级冷流道+一级热流道组成。所获得的浇注效果为:引起浮纤发生的内外壁模温差控制在38℃以下(标准值≤50℃);主要外观面盖面的纤维取向张量范围为0.7373~0.9986,能有效保证盖面的结构强度;塑件最大翘曲变形量为1.024 mm,能保证塑件关键尺寸的成型精度满足MT3级A类精度要求;基于玻纤增强的模腔成型收缩率各向差异化设置分别为X向0.3%,Y向0.1%,Z向0.2%。与优化结果对应的注塑工艺参数为:模温89.4℃,料温292.4℃,注射压力92 MPa,冷却水温度25℃,注塑周期38 s。模具结构为一种两板式热流道模具,一模两腔布局,模具中采用脱模方向集成法设计了3种脱模机构,其中的定模推板斜顶机构和油缸推板型斜抽芯机构对同类塑件脱模机构设计有较好的参考作用。

沅江芦笋可溶性膳食纤维提取工艺的优化

以沅江芦笋为原料,通过超声辅助酶法提取可溶性膳食纤维,探讨α-淀粉酶与糖化酶质量比、浸提时间、超声功率、超声温度以及料液比对可溶性膳食纤维提取得率的影响,并采用正交试验优化可溶性膳食纤维最佳提取工艺。结果表明,最佳提取工艺条件为料液比1∶200(g/mL),α-淀粉酶与糖化酶质量比5∶5,浸提时间4 h。在该工艺条件下沅江芦笋可溶性膳食纤维提取得率为16.77%。

连续碳纤增强B柱加强板结构设计与铺覆仿真

针对连续纤维复合材料成型过程中在大曲率位置易导致纤维断裂、褶皱、撕裂等缺陷问题,本文基于连续纤维复合材料随模铺覆仿真方法,理论分析了铺覆起点、初始取向对铺覆效果的影响规律。以减少纤维成型缺陷为目标,开展了连续碳纤维增强复合材料B柱加强板的结构优化和铺覆优化设计,确定了面向热压成型工艺的B柱加强板几何结构和预浸料铺覆方式。通过分块铺覆优化,使0°、90°、45°、-45°的铺层不合格占比分别由45.18%、52.83%、72.21%、71.78%降至2.47%、3.45%、5.31%、4.77%,有效提高了连续碳纤维的随模铺覆性。基于优化的铺覆设计,成功试制出满足性能要求的B柱加强板。

Experimental investigation of engineered geopolymer composite for structural strengthening against blast loads

The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.

3D打印连续纤维复合材料工艺、结构优化研究进展

连续纤维增强复合材料由于优异的比强度、比刚度、可设计性和轻量化特质,日益受到航空航天等高端装备制造领域的青睐.3D打印技术的发展改变了连续纤维复合材料结构的生产制造流程,使复杂结构的自由成型成为可能,为先进结构材料提供了巨大的设计空间.为充分发挥先进材料性能优势和3D打印成型灵活性,研究人员分别从材料性能和结构设计出发,探索与3D打印连续纤维复合材料相适应的设计制造一体化解决方案,实现产品创新设计和性能提升.本文系统性地回顾了面向连续纤维复合材料性能分析、工艺改进和结构优化的研究工作,结合研究实践对连续纤维复合材料的结构多尺度优化方法进行总结分析,并对未来先进材料结构设计实时化、功能化、智能化的发展趋势进行探讨和展望.

山羊绒/Optim纤维混纺针织纱的开发

文章分析了山羊绒和拉细羊毛Optim的性能及特点,围绕Optim纤维与山羊绒混纺针织纱的产品开发,讨论了复精梳工艺、前纺及细纱各工序在生产中存在的问题,并提供了解决方法;同时讨论了各工序工艺参数的选择及复精梳后再混入羊绒的原因。该工艺可充分发挥2种纤维的特性,为拉细羊毛纤维的产品开发提供借鉴。