管道修复用管状非织造布复合材料的结构设计

基于修复大管径管道对管状非织造布复合材料强度与厚度的要求,对管状非织造布复合材料的结构进行了设计。通过在非织造布中加筋增强了其强度;加筋非织造布设计块数在2块和2块以上,形成管状非织造布复合材料在周向接缝等距离设置的结构,这种多接缝的管状非织造布复合材料结构对称,在翻衬时避免单个接缝应力集中现象,从而防止了在接缝处出现开裂;在每块加筋非织造布覆膜时,两侧预留缝合区域,减少了缝合难度,增加了缝合效率,而且降低了缝合处的厚度,使得接缝处更容易膜焊接,保证了整个管状非织造布复合材料的密封性。最后通过实验验证了结构设计的合理性。     

青海湖沙化地区石膏基固沙植生复合材料植物相容性效果试验

以石膏基固沙复合材料为基体,利用适合青藏高原沙漠化地区生长的5种植物草种,在青海湖周边进行固沙植生野外效果试验研究,对石膏基固沙复合材料固结层沙层进行了温度、含水量测试,并探讨了不同配合方式的草种与石膏基固沙复合材料混合植生试验的植物相容性机理.结果表明,石膏基固沙复合材料对沙层内部起到一定的控温保湿作用,日光照射不强时,图沙材料草种混合后种植的试验小区的沙层温度高于不含固沙材料种植草种的试验小区的温度,在日光照射变强时,这种影响反而相反;固结层沙层深度在3～12 cm处,固结层对沙丘内部含水量的影响最显著,当深度达到12～15 cm处,这种保湿作用缓慢变小;采用固沙材料和5种植物草种混合搅拌及固沙材料形成洞穴后分别种植5种植物草种的配合方式,圉沙材料与植物相容性效果显著,发芽率均大于80％以上.这为青海湖周边沙化地区提供有效的固沙材料与沙生植物奠定了基础.     

纺丝工艺对静电纺纳米纤维包芯纱包覆性能的影响

提出了一种制备连续纳米纤维包芯纱的方法,利用接地平行铝片作为接收装置,使得纳米纤维平行地搭接在2块铝片之间,处于2块铝片中央的芯纱通过绕自身纱轴旋转,将取向的纳米纤维卷绕在其表面。研究了平行铝片间距、纺丝电压、纺丝距离以及溶液流量对纳米纤维包芯纱包覆率及耐磨性的影响规律。结果表明,利用该方法制备的纳米纤维包芯纱包覆较为均匀,无露芯现象,并且芯纱表面纳米纤维直径分布均匀,排列整齐且具有良好的取向度。当平行铝片间距为2 cm,电压为17 k V,纺丝距离为14 cm,流量为1.0 m L/h时,电纺过程较稳定,包覆效果较好,包覆率最高可达41.9%,并且所得纳米纤维包芯纱的耐磨性与其包覆率成正相关关系,增磨率最大可达142.3%,同时其力学性能较原纱也有略微提高。     

三维五向管状织物纱束轨迹及纤维体积分数的分析与研究

针对四步法编织的三维五向管状织物,基于圆形编织的纱束运动过程及机理分析,研究了织物内部与表面纱束的几何拓扑关系,继而提出三维五向管状织物的单胞结构模型。在此基础上,分别用阿基米德螺旋线段和圆弧段近似预成型内部与表面的纱束轨迹投影,并给出相应的数学描述。根据单胞几何特征,提出了织物横截面上不同位置处的纤维体积分数计算方法。通过建立纱束数据结构及运用计算机可视化技术,对纱束空间轨迹及横截面纤维体积分数进行了模拟显示。这对表征三维五向管状织物的结构性质、实现编织参数优化设计有着重要的意义。      

可生物降解聚乳酸/助剂/聚丙烯复合纺粘非织造布的制备与性能研究

以聚乳酸(PLA)、聚丙烯(PP)为原料,以自制马来酸酐接枝物为助剂,通过综合纺丝机熔融共混制备可生物降解PLA/助剂/PP复合纺粘非织造布,研究纺丝温度、计量泵转速、热辊温度和助剂用量对非织造布物理性能的影响;对牵伸前后的纤维进行了热学性能分析。结果表明,纺丝温度170℃、计量泵转速25r/min、热辊温度60℃及助剂用量12%(wt,质量分数)为复合非织造布的最优制备工艺条件;复合纤维经过牵伸后,总结晶度得到提高。     

梯度结构双组份纺粘水刺超细纤维非织造布透气性能数值模拟

为探究梯度结构对双组份纺粘水刺超细纤维非织造布透气性能的影响,采用三步法工艺制备了系列梯度结构双组份纺粘水刺超细纤维非织造布并测试其特征参数;利用Geodict软件建立了梯度结构双组份纺粘水刺超细纤维非织造布的三维纤维分布模型,分析了梯度结构对超细纤维非织造布的流速、流线和流场压力的影响,预测了其透气系数,结果分别为3544.07 mDarcy,2527.90 m Darcy,2320.68 m Darcy,1860.18 mDarcy和1770.46 mDarcy。得到的模拟结果与实验数据吻合良好,验证了模拟结果的有效性,揭示了梯度结构与性能之间的构效关系,且表明梯度结构明显的双组份纺粘水刺超细纤维非织造布具有较高的透气性能。     

静电纺PLA管状支架的结构及其生物力学性能

以具有良好生物相容性、生物可降解性的聚乳酸(PLA)为原料,通过静电纺丝法,以高速旋转的滚轴为收集装置,制备了PLA小口径管状支架(d=4.5mm).研究了不同工艺对PLA管状支架形态结构、孔隙率和生物力学性能的影响.结果表明:随着纺丝液质量分数的增加,纤维直径增大,孔隙率减小,断裂强度提高;当滚轴转速为2000r/min时,可获得取向很好的纤维,此时,PLA管状支架的孔隙率最小,断裂强度最大,其爆破强度远高于人体正常血压;随着管壁厚度的增加,PLA管状支架的孔隙率减小,其断裂强度及爆破强度均增加.     

医疗用非织造材料的加工技术及发展

结合非织造材料在医疗领域的发展现状,选取了4种医疗非织造布所使用的原材料,从本身特性及在医疗中应用优势出发,介绍了聚丙烯、聚乳酸纤维、生物基纤维、再生纤维素纤维的研究现状;再从工艺特点与用途方面,阐述了纺粘法、熔喷法、SMS复合技术、纺粘水刺复合技术4种医用非织造布加工技术;重点总结出国外医用非织造布新型加工工艺,包括后整理工艺、静电纺技术以及其他改进工艺,介绍了新型工艺改进流程、改进后特性及在未来医疗中的应用;为医用非织造材料的选择与加工提供一定的理论依据和技术支持。     

柔性纺织电阻传感器的研究进展

纺织电阻传感器具有质量轻、柔性好和可拉伸等优良特性,在可穿戴电子产品领域具有很大的应用价值。文中根据近年来不同纺织材料基电阻传感器的研究进展,介绍了无捻纤维(束)基电阻传感器、纱线(长丝纱、短纤维纱、复合纱)基电阻传感器和织物(针织物、机织物、非织造织物)基电阻传感器的制备、性能及应用研究。在纱线基电阻传感器中,主要基于导电涂覆纱线受力过程中纤维的内在弹性或长丝之间接触程度的变化所引起电阻改变的原理,制备电阻传感器;对于织物电阻传感器,主要利用织物结构体的变形特征并结合对织物进行导电涂覆或碳化等方法,制备电阻传感器。     

复合结构防护口罩材料的制备及性能研究

利用静电纺丝技术,在粘胶水刺非织造基表面沉积时长分别为9 min、11 min、13 min、17 min、21 min、25 min、29 min,质量分数为13％的醋酸纤维素(CA)载药纳米纤维,药物为没食子酸(GA),再在表层覆盖丙纶纺粘非织造布,作为复合结构防护口罩材料.采用扫描电镜对非织造布及载药纳米纤维膜进行形貌表征,测试其孔径大小及分布,并进行了过滤效率、过滤阻力、抗菌性能测试.结果表明:在实验范围内,纳米纤维连续均匀,负载药物后的纳米纤维比纯CA纳米纤维直径稍粗,但直径更加均匀;随纺丝时间延长,复合结构材料孔径变小、孔径分布更均匀;并且对1μm以下的粒子的过滤效率从24.12％提高到69.76％左右,但对过滤阻力影响不大;复合结构材料对大肠杆菌和金黄色葡萄球菌的抑菌圈宽度分别达到1.40 cm和2.30 cm,具有良好抗菌抑菌性能.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...