降落伞用锦纶伞材织物的防灼和阻燃研究

对降落伞用锦纶伞材织物的防灼及阻燃整理进行了研究及开发,研制出的防灼剂及防灼工艺有效地解决了以锦纶为主要原料的飞机机载降落伞的灼伤问题,在使用过程中可将灼伤率降低70%以上;同时研制出了一种新型阻燃单体,采用光引发接枝阻燃后处理技术,有效地改善了锦纶的阻燃性能,同时其力学性能变化不大。     

特纺材料拉伸耐久性能的试验研究

阻力伞是航空救生领域中可以多次反复使用的产品。特纺材料作为阻力伞的主体材料,在复杂条件下的拉伸性能应满足产品设计和使用需要。模拟阻力伞任务环境和工作条件,依据产品寿命期间的使用次数要求,参照材料使用工况,开展主体特纺材料在持续承载和反复拉伸等模式下的耐久性能研究,研究内容包括试验方案和试验步骤设计、试验验证和结果分析等,目的是为设计、工艺及试验人员提供技术支撑和服务。     

纺织品色差定量评定方法分析

纺织品色差评定是材料外观质量的重要项目。目视色差评定主要采用灰色样卡将试样与标样进行比对,评定结果受光线和评定者主观情绪的影响较大。以飞行员救生服装和降落伞用纺织品为对象,利用色差计进行色差评定数据定量化分析。结果表明,色差计测量准确,可用于材料验收和产品交付等质量控制。     

纺织品缝合强度试验方法改进

纺织品是飞行员个体防护救生服装、军用伞等装备和产品的主体材料,需要以特定的方式进行缝合。缝合强度不仅体现缝纫工艺的优劣性,还是产品选材和结构设计的重要依据。试验以航空救生领域产品技术条件对于结构强度设计要求为出发点,结合现有缝合强度试验过程中存在的问题,从试样制备、试验夹具设计等方面来进行纺织品缝合强度改进的试验研究和验证。结果证明,此研究方法可以真实、准确地反映纺织品的缝纫性能,为特纺材料的设计提供有价值的参考数据,对于提升中国个体防护救生装备的技术水平有着重要的意义。     

芯材密度对复合材料夹层梁弯曲力学性能影响

研究了聚氨酯泡沫密度对复合材料夹层梁弯曲力学性能的影响。首先,对5种不同密度(48~413kg/m3)泡沫芯材复合材料夹层梁进行三点弯试验研究,结果表明,夹层梁极限承载力随芯材密度的增大而增大;当芯材密度大于等于199kg/m3时,继续增大泡沫密度,夹层梁极限承载力增加速度变慢;随着芯材密度的增加,夹层梁破坏模式由芯材压陷变为面板受压屈服破坏。其次,基于考虑芯材竖向压缩变形的高阶剪切变形理论,对不同试验梁弯曲受力机理进行弹性分析,得到夹层梁上、下面板挠度变化及应变分布规律,并与试验结果对比,验证了理论分析方法的正确性。最后,对试验过程中夹层梁典型的破坏模式进行极限承载力分析,提出其极限承载力计算公式,并与试验结果对比,结果吻合良好。     

橡胶丝弹性垫材

江苏省化工研究所研制了一种用于弹性垫材的聚氨酯粘合剂 ,它与橡胶丝结合而生产的橡胶丝弹性体垫具有优异的防渗、抗震、防湿滑性能。橡胶丝弹性垫材由旧轮胎等废旧橡胶经造丝、分选及染色后 ,与聚氨酯粘合剂混合模压而成。预成型的垫材铺设简便 ,可用于幼儿园、游乐园、训练场及公共走廊等场所。垫材的密度约 0 .72ｇ/ｃｍ3 ,回弹率 33% ,拉伸强度 4.2ＭＰａ ,伸长率 15 0 %。橡胶丝弹性垫材产品 1998年 11月获国家科技部、国家环保总局等五部委颁发的国家重点产品证书 ,1999年在江苏省石化厅幼儿园等处铺设 ,使用效果良好。橡胶丝弹性垫…     

粘土水泥浆材流变性能及其对灌浆的影响

粘土水泥浆材性能优越,已广泛应用于水利、矿山、垃圾填埋场等防渗堵漏及基础加固工程,浆材的流变性能对其可灌性和扩散距离有重要影响.利用Broolfield+ R/S流变仪对层流状态下不同配比的粘土水泥浆材的流变参数进行了试验研究,探讨水固比、粘土掺量、温度和岩土体吸附作用及压滤作用等因素对其流变性能的影响.结果表明:粘土掺量对水固比为0.6∶1与1∶1的浆材流变参数影响显著,对水固比为1.5∶1与2∶1的浆材影响微弱;同配比浆材在不同温度下有不同的流变模型.由于岩土体对浆材的吸附作用,浆材的粘度和屈服应力随时间逐渐增大;浆材在岩土体中的压滤效应对粘土水泥浆的流变特性影响较纯水泥浆小,但是同样空隙条件下,粘土水泥浆材更易发生压滤效应.浆材流变性能对其扩散距离的影响显著,粘土水泥浆材的扩散距离明显小于水泥浆材.     

废轮胎制砖材新技术提高砖材耐用性

据专家吴荣光,吴荣照介绍,本技术方案是使用粉碎成细小片状的废轮胎,制成由弹性层、支撑层及再加在其上面的弹性层构成的具有3层叠层结构的砖材,通过保证良好的耐用性、坚固性和弹性,使得施工者和行人满意的用废轮胎碎片生产的砖材及其制造方法。该技术生产的产品具有的稳定感、可保持一定重量感、具有弹性、良好耐用性及坚固性等特点,生产出的产品还拥有多种用途。专家吴荣光,吴荣照说,本技术生产砖材时具有下列3层结构,即由100重量份橡胶颗粒、3～10重量份粘合剂、0.5～5重量份颜料形成的上部弹性层;由100重量份细骨架材料、5～20重量份橡胶片、10～15重量份粘合剂构成的中间支撑层;用与上部弹性层同样条件在上述支撑层下面叠层形成的下部弹性岐所构成的一体化的3层结构。专家吴荣光,吴荣照介绍说,砖材制造方法主要为以下工序:将下部弹性层材料投入到模具中,该下部弹性层材料是在粉碎成     

面板厚度对复合材料夹层梁整体及局部弯曲力学性能影响

考虑芯材局部压陷效应,对泡沫夹芯复合材料夹层梁整体及局部弯曲力学性能进行研究。分析了上面板厚度对夹层梁整体及局部弯曲力学性能影响规律。首先,对三种不同厚度上面板夹层梁进行三点弯曲试验,结果表明,夹层梁破坏模式为芯材压陷破坏和芯材剪切破坏;上面板厚度越大,夹层梁极限承载力越大;增大上面板厚度能有效减弱加载点位置芯材局部压陷效应。其次,基于考虑芯材竖向压缩变形的高阶剪切变形理论,对试验梁整体及局部弯曲受力机理进行分析,得到夹层梁上、下面板不同位置挠度及应变的分布规律。最后,对不同试验梁极限承载力进行理论分析,并与试验结果对比。     

硬木家具上蜡装饰表面耐光性研究

为研究不同上蜡工艺装饰后硬木家具表面的耐光性,本文以大果紫檀为基材,分别对其传统烫蜡材、溶剂型漆托蜡材与水性漆托蜡材等3种上蜡工艺装饰的木材进行紫外光加速照射,测定在光照过程中其表面颜色、光泽、纹理等变化,并利用傅里叶红外光谱观察不同上蜡材表面的化学组成及光照中化学成分的变化。结果表明:溶剂型漆托蜡材与水性漆托蜡材的耐光性优于传统烫蜡材;而且,传统烫蜡涂层可在短时间内延缓木材的老化,长时间的光照下蜡层基本失去了保护作用。     

Study on the Application of the Combination of TMD Simulation and Umbrella Sampling in PMF Calculation for Molecular Conformational Transitions

Free energy calculations of the potential of mean force (PMF) based on the combination of targeted molecular dynamics (TMD) simulations and umbrella samplings as a function of physical coordinates have been applied to explore the detailed pathways and the corresponding free energy profiles for the conformational transition processes of the butane molecule and the 35-residue villin headpiece subdomain (HP35). The accurate PMF profiles for describing the dihedral rotation of butane under both coordinates of dihedral rotation and root mean square deviation (RMSD) variation were obtained based on the different umbrella samplings from the same TMD simulations. The initial structures for the umbrella samplings can be conveniently selected from the TMD trajectories. For the application of this computational method in the unfolding process of the HP35 protein, the PMF calculation along with the coordinate of the radius of gyration (R_g) presents the gradual increase of free energies by about 1 kcal/mol with the energy fluctuations. The feature of conformational transition for the unfolding process of the HP35 protein shows that the spherical structure extends and the middle α-helix unfolds firstly, followed by the unfolding of other α-helices. The computational method for the PMF calculations based on the combination of TMD simulations and umbrella samplings provided a valuable strategy in investigating detailed conformational transition pathways for other allosteric processes.     

实验室用脱泡装置的设计与计算

基于实验室的特点设计脱泡装置。分析了影响脱泡过程的因素。基于一定的数学模型,采用微积分的方法得到设计脱泡装置的计算公式,包括:气泡的逸出速度、液膜厚度、停留时间、分配管管径等,从而计算伞面长度。经检验,自制的脱泡装置大大提高了脱泡效率。     

计算流体力学在氧化沟设计中的应用

利用计算流体力学对氧化沟的倒伞曝气机及推流器建立叶轮机械驱动模型,建立氧化沟污水-污泥多相流模型,利用计算流体力学软件Fluent对倒伞曝气机及推流器驱动的氧化沟进行流场模拟,能够较为准确的预判各种情况下的流场,有效地整合表面曝气机与潜水推流器的统一,能够很好地对氧化沟工程设计,设备配置及布置等起优化作用,并对污水厂运营起指导作用。     

Detection of similar successive groups in a model with diverging number of variable groups

Abstract

In this article, a linear model with grouped explanatory variables is considered. The idea is to perform an automatic detection of different successive groups of the unknown coefficients under the assumption that the number of groups is of the same order as the sample size. The standard least squares loss function and the quantile loss function are both used together with the fused and adaptive fused penalty to simultaneously estimate and group the unknown parameters. The proper convergence rate is given for the obtained estimators and the upper bound for the number of different successive group is derived. A simulation study is used to compare the empirical performance of the proposed fused and adaptive fused estimators, and a real application on the air quality data demonstrates the practical applicability of the proposed methods.     

On the Consistency of the Exfoliation Free Energy of Graphenes by Molecular Simulations

Monolayer graphene is now produced at significant yields, by liquid phase exfoliation of graphites in solvents. This has increased the interest in molecular simulation studies to give new insights in the field. We use decoupling simulations to compute the exfoliation free energy of graphenes in a liquid environment. Starting from a bilayer graphene configuration, we decouple the Van der Waals interactions of a graphene monolayer in the presence of saline water. Then, we introduce the monolayer back into water by coupling its interactions with water molecules and ions. A different approach to compute the graphene exfoliation free energy is to use umbrella sampling. We apply umbrella sampling after pulling the graphene monolayer on the shear direction up to a distance from a bilayer. We show that the decoupling and umbrella methods give highly consistent free energy results for three bilayer graphene samples with different size. This strongly suggests that the systems in both methods remain closely in equilibrium as we move between the states before and after the exfoliation. Therefore, the amount of nonequilibrium work needed to peel the two layers apart is minimized efficiently.     

Effect of surface conditions related to machining and air exposure on wettability of different Mediterranean wood species

Wettability of 6 different wood species commonly used in the woodworking industry in the Mediterranean region was evaluated in this study. The species were Norway spruce (Picea abies Karst.), umbrella pine (Pinus pinea L.), oak (Quercus sp.p.), chestnut (Castanea sativa Mill.) beech (Fagus sylvatica L.) and poplar (Populus sp.p.), and their surfaces were machined according to 3 different processes: planing, sanding and disc-sawing. Measurement of dynamic contact angle and extractives (evaluated by means of GC–MS analysis) were carried out on freshly cut and 24 h air exposed surfaces, in order to also evaluate the effect of ageing on wettability. The parameterisation of the contact angle vs. time curves allowed for the systematic statistical elaboration of data, in order to find the relationships existing between the four parameters characterising the dynamic curves and the considered factors (species, machining, ageing). The evaluations evidenced a different influence of these factors on the chosen parameters and hence some of them could be used to reliably assess both wood wettability and the effects of the factors here considered. In general softwoods showed higher contact angles than hardwoods due to the different anatomy and to the presence of resins and terpenes in addition to fatty acids and phenolic compounds, also present in hardwoods. After 24 h air exposure a shifting upwards of dynamic contact angle curves was observed but, despite the variation in surface composition, this shifting was imputable to other inactivation factors. Also machining appreciably influenced wettability, and the sanded surfaces were the most wettable as compared to both the planed and the disc-sawn ones. On the other hand, these observed differences diminished after ageing due to the levelling effect of inactivation that overcame surface inhomogeneities.     

Effect of initial slight oxidation on stability of polyunsaturated fatty acid/protein mixtures under controlled atmospheres

A mixture of unsaturated fatty acids (FA), mainly linolenic acid, and bovine serum albumin (BSA) was incubated under several different atmospheres to study the effect of these atmospheres on the stability of FA to oxidation. Four experiments were carried out simultaneously, which consisted of the incubation of the FA/BSA mixture under air, nitrogen, air in the presence of 200 ppm of butylated hydroxytoluene, and air for 6 h and then under nitrogen. The four experiments were tested for lipid oxidation and color changes by measuring absorbances at 234 and 270 nm, formation of thiobarbituric acid-reactive substances, and color differences and yellowness index. The samples that were oxidized with air before storage under nitrogen were the most stable against lipid peroxidation and exhibited the smallest color changes. These results suggest that a slight and controlled lipid oxidation improved the oxidative stability of FA/BSA mixtures.     

Effect of initial slight oxidation on stability of polyunsaturated fatty acid/protein mixtures under controlled atmospheres

A mixture of unsaturated fatty acids (FA), mainly linolenic acid, and bovine serum albumin (BSA) was incubated under several different atmospheres to study the effect of these atmospheres on the stability of FA to oxidation. Four experiments were carried out simultaneously, which consisted of the incubation of the FA/BSA mixture under air, nitrogen, air in the presence of 200 ppm of butylated hydroxytoluene, and air for 6 h and then under nitrogen. The four experiments were tested for lipid oxidation and color changes by measuring absorbances at 234 and 270 nm, formation of thiobarbituric acid-reactive substances, and color differences and yellowness index. The samples that were oxidized with air before storage under nitrogen were the most stable against lipid peroxidation and exhibited the smallest color changes. These results suggest that a slight and controlled lipid oxidation improved the oxidative stability of FA/BSA mixtures.     

伞板形液体布膜装置结构及布膜性能研究

对适用于垂直管降膜蒸发器的伞板形液体布膜装置的结构进行了介绍,给出了伞板形液体布膜装置与换热管内壁之间的环隙的计算公式。并对其成膜性能进行了实验研究,得到了液体雷诺数、液体布膜装置的结构与液体成膜不均匀度系数之间的关系。     

气流预分散对涡流空气分级机分级性能的影响

在物料进入涡流空气分级机前采用了气流预分散装置,使物料悬浮分散并输送到分级机中。以滑石粉和石灰石粉料为原料进行分级实验,研究不同条件下气流预分散对分级性能的影响。采用激光多普勒测速仪对分级机内环形区流场进行速度测定,分析预分散气流对流场的影响。结果表明,当预分散气速大于1.1 m/s时,细粉产率、牛顿分级效率和切割粒径随预分散气速的增大而增加;在不同的系统进口风速条件下,物料预分散后,细粉产率、牛顿分级效率增加;平均粒径小的石灰石粉料其中含有的超细颗粒(<4μm)不易实现气流预分散,预分散气流可以明显地减小对分级不利的轴向速度。