Relationships between the Tensile Properties and Tenacity-extension Behaviour of Fibre-bundles

Fibre bundle testing is different from single-fibre measurement, not only in testing methods and instruments, but in the results obtained. For wool fibres, Sirolan-TENSOR can supply fibre-bundle tenacity (BS) and bundle extension (BE), but has some limitations on the analysis of the measured tensile curves of fibre bundles. It has not only raised new parameters,such as initial modulus (BM) and specific work of rupture (BW), as well as the specific work before or after the peak-point(WBP or WAP) and the ratios of WAP/WBP and WAP/BW, but also compared the tensile behaviour of different fibre-bundles, e.g. wool,polyester and viscose rayon fibre- bundles. The experimental results from 32 lots of wool tops show that there are correlations between bundle tensile properties,such as BS-BE, BS-BM, BS-BW, BE-BW and BM-BW.However, the variables of coefficients of variance (CV)are almost independent of each other and have no correlation with the average values of fibre bundle tensile parameters, except for BS-CVBM and CVBM-BW.

New Bounds on Tenacity of Graphs with Small Genus

A new lower bound on the tenacity ?of a graph G in terms of its connectivity and genus is obtained. The lower bound and interrelationship involving tenacity and other well-known graphical parameters are considered, and another formulation introduced from further bounds are derived.

Nest site tenacity and mate fidelity in the Black-headed Gull(Chroicocephalus ridibundus)

Breeding philopatry is well known in the Black-headed Gull(Chroicocephalus ridibundus).Using a capture-markrecapture method,we studied if Black-headed Gulls show nest site tenacity and mate fidelity as well,and investigated if there are differences between a stable,and a newly established and fast-growing colony,as well as for differences between the center and edges of these colonies located in north-eastern Germany.We found a high level of nest site tenacity in the center of the stable colony on B?hmke Island,and lower degrees of nest site tenacity at the edge of the same colony and in the newly established and fast-growing colony on Riether Werder.Mate fidelity was very strong in all individuals which returned to their previous breeding place,regardless of the nest site location.

Production of super-high strength aluminum alloy billets by low frequency electromagnetic casting

The effects of low frequency electromagnetic field on the macro-physical fields in the semi-continuous casting process of aluminum alloys and the microstructure and crack in the billets were studied and analyzed by the numerical and experimental methods.Comparison of the results for the macro-physical fields in the low frequency electromagnetic casting（LFEC） process with the conventional DC casting process indicates the following characters due to the application of electromagnetic field：an entirely changed direction and remarkably increased velocity of melt flow;a uniform distribution and a decreased gradient of temperature;elevated isothermal lines;a reduced sump depth;decreased stress and plastic deformation.Further,the microstructure of the billets is refined remarkably and the crack in the billets is eliminated in LFEC process because of modification of the macro-physical fields induced by the application of low frequency electromagnetic field.

Lyocell纤维的特性与应用前景

Lyocell纤维作为当下再生纤维素纤维中相对前沿且绿色环保的材料,相比涤纶拥有更好的吸湿性及可降解性,相比棉纤维及其他再生纤维素纤维拥有更高的强力及更光滑的截面。这些特点使得Lyocell纤维能够在服装、家纺、非织造及产业用纺织领域拥有其独特的应用范围。近年来,随着国内Lyocell纤维产能的提升,许多下游企业在Lyocell纤维的应用开拓上开展了大量的研究工作。简述了基于当前研究背景下的Lyocell纤维的性能及其在纺织、非织造和复合材料领域的应用,并探讨了Lyocell纤维未来应用的前景。

锭帽式假捻装置在环锭纺上的应用效果研究

为降低低捻纱的断头率,提高低捻纱的成纱质量,设计了可直接安装在细纱管上的锭帽式假捻装置。采用不同直径和不同表面结构的锭帽式假捻装置分别纺制24.4 tex低捻羊毛单纱,测试其断裂强度、断裂伸长率和毛羽数,并与常规环锭纺低捻纱进行对比。结果表明:采用锭帽式假捻装置纺出纱较相同捻度常规纱的断裂强度提高10%左右,断裂伸长率提高30%左右,断裂功提高30%左右,长毛羽(4 mm~9 mm)数降低8%左右;总体而言,光滑锭帽比凸条锭帽对成纱质量的改善效果更好;锭帽假捻装置的直径对上述指标也有影响,凸条锭帽的直径为48 mm、52 mm和54 mm时,假捻效果较好;光滑锭帽的直径为44 mm、56 mm和58 mm时,假捻效果较好。认为:所设计的锭帽式假捻装置结构简单、安装方便、无能源消耗,可有效提高环锭纺羊毛低捻纱的成纱质量,具有很好的应用价值。

抗菌发热功能性粘胶纤维的制备及性能分析

为了制备具有抑菌、发热功能的粘胶纤维,采用β-环糊精包覆姜辣素制得微胶囊,然后将微胶囊加入粘胶纺丝液,通过纺前共混、湿法纺丝工艺制得姜辣素粘胶纤维。借助扫描电镜、红外光谱仪、单纤维强力仪等对制备的姜辣素粘胶纤维、粘胶纤维的结构和性能进行表征与分析,并测试了所织针织物的抗菌性能和发热性能。结果表明:所制备的姜辣素粘胶纤维中位粒径D50为0.599μm,90%粒径在1.293μm以下;具有与粘胶纤维相近的微观结构,但纵向沟槽增多;姜辣素粘胶纤维在1 450 cm^(-1)附近出现不同于粘胶纤维的苯环骨架振动峰;相较于粘胶纤维,姜辣素粘胶纤维的断裂伸长率和干、湿断裂强度都有一定程度下降,但仍然达到一等品标准要求。姜辣素粘胶纤维针织物抑菌率达到抗菌针织品AAA级标准;织物吸湿后30 min内升温值最高达到11℃,平均值达到5.1℃,满足技术标准要求;相比于粘胶纤维,姜辣素粘胶纤维针织物摩擦50次和100次后升温值分别提高0.8℃和1.4℃,具有较好的发热功能。

Population Construction and Super-high Yield Characteristics of Japonica Super Rice in Cold Regions

[Objective] This study was conducted to construct a super-high yield population of Japnica rice in cold regions of North China and to explore its characteristics. [Method] The super rice variety Longjing 21 was selected as the experimental material. Different row spacing（two levels）, plant spacing（three levels） and seedling number per hill（three levels） were designed in field trials. Then, the growth stages,dry matter accumulation, leaf area, yield and yield components of these different treatments were measured. [Result] Rice yield had significantly negative correlation with plant spacing and row spacing, but no significant correlation with seedling number per hill. Rice yield was mainly affected by plant spacing, and less affected by seedling number per hill. The best recommended specifications for plant spacing of super rice variety Longjing 21 were 24 cm for row spacing, 12 cm for plant spacing and five seedlings per hill, and the expected yield was 10 473.0 kg/hm^2.The increased number of total spikelets（4.5×108hm2or more） in populations was the major reason for high yield. Super-high yield populations had fewer tillers at the early growth stage and achieved the expected number of productive tillers at critical leaf-age（June 25）, and tiller number peaked at jointing stage（July 6） and was about 1.2 times of the expected number. The percentage of productive tillers in total tillers of super-high yield population was more than 85% at heading stage. At middle growth stage（from jointing to heading stage）, the dry matter accumulation, leaf area index（LAI） at heading stage, effective leaf area, spikelet number of population,spikelet number per leaf area unit（cm2）, and culm-sheath weight per stem of super-high yield population were significantly higher than those of other populations.At late growth stage（from heading to maturity stage）, the leaf area decreasing rate of super-high yield population was significantly smaller than that of other populations. At late growth stage（from heading to maturity stage）, the leaf area decreasing rate, crop growth rate, net assimilation rate, biomass accumulation, number of filled grains per leaf area unit（cm^2） and grain weight per leaf area unit（cm^2） of high-yield population were significantly higher than those of other populations. Output and translocation of dry matter（weight per stem and sheath and total filling rate at maturity） from heading to milky stage of super-high yield population were significantly higher than those of other populations. [Conclusion] The characteristics of superhigh yield rice in cold region of North China are enriching the amount of actual filling of sink through improving photosynthetic efficiency from heading to maturity stage on the basis of enough panicle numbers.

基于粘结性能的高黏改性剂与沥青配伍性研究

现有黏韧性评估方法使用的金属拉头并不能真实反映沥青与集料的粘结能力,为此提出新的黏韧性评估方法,并以黏韧性、韧性为核心指标对2种高黏改性剂与3种沥青进行配伍性试验。结果表明:改性沥青与高黏改性剂M-9314和HVA的配伍性优于基质沥青,且最佳配伍沥青为I-D改性沥青。当高黏改性剂掺量相同时,改性沥青的黏韧性与高黏改性剂中SBS的含量无关,而与改性沥青中SBS的交联状态有关。同时,集料-沥青粘结评估方法的黏韧性与金属-沥青粘结评估方法的黏韧性存在较好的相关性,且集料-沥青粘结评估方法更接近实际情况,建议集料-沥青粘结评估方法的黏韧性指标为:黏韧性>15 N·m,韧性>10 N·m。

常温固化下偏高岭土基高韧性地聚合物复合材料的性能研究

以偏高岭土为前驱体,在常温固化条件下制备了高韧性地聚合物复合材料(HTGC),研究了不同粒径偏高岭土的复掺比例、激发剂的浓度和模数、养护龄期对HTGC抗压、抗拉和抗弯性能的影响。结果表明:复掺适量不同粒径的偏高岭土有利于提高HTGC的抗压和抗拉性能;随着激发剂浓度从6 mol/L增至14 mol/L,试件的抗拉和抗压强度增大,拉伸和抗弯延性有所降低;随着激发剂模数从1.2增至2.0,试件抗压和抗拉强度基本有所降低;偏高岭土基HTGC具有明显的早强特性,这使其在快速建造项目中具有较大的应用潜力。

影响高黏改性沥青黏韧性、韧性指标的因素探究

考察了不同基质沥青种类、改性剂掺比、SBS改性剂掺量、增黏树脂种类、助剂添加以及黏韧性试验制样方式对高黏改性沥青黏韧性、韧性指标的影响。结果表明:采用C公司基质沥青,SBS添加量为8%,树脂种类选择酚醛树脂或者萜烯树脂,不额外添加纳米蒙脱土等助剂及提高半球圆头的预热温度至160℃,均有利于高黏改性沥青黏韧性、韧性指标。

不同掺量SBS改性沥青黏韧行为研究

SBS具有特殊的软硬链段结构,可在沥青中形成稳定的聚合物三维网络结构,因此,SBS改性沥青具备优异的性能。目前,传统三大指标无法充分评价SBS改性沥青的性能。为此,通过黏度、黏韧性和测力延度等黏弹性试验指标对SBS掺量对沥青性能的影响规律进行研究,并与三大指标试验结果进行对比。结果表明:随着SBS掺量的增加,沥青的三大指标、动力黏度、布氏旋转黏度、车辙因子逐渐增大。6%掺量的SBS对沥青常规性能和高温失效温度的提升最为明显。相比基质沥青,SBS改性沥青的最大拉力值增加且应力松弛时间延长。6%SBS掺量下SBS改性沥青的低温延展性最佳,8%掺量下SBS改性沥青黏韧性能最佳且韧性部分提高最多,增韧效果显著。相关性分析表明,沥青60℃动力黏度对数值、70℃车辙因子对数值与黏韧性指标线性相关性较强。

Optimization design of foundation excavation for Xiluodu super-high arch dam in China

With better understanding of the quality and physico-mechanical properties of rocks of dam foundation,and the physico-mechanical properties and structure design of arch dam in association with the foundation excavation of Xiluodu arch dam,the excavation optimization design was proposed for the foundation surface on the basis of feasibility study.Common analysis and numerical analysis results demonstrated the feasibility of using the weakly weathered rocks III1and III2as the foundation surface of super-high arch dam.In view of changes in the geological conditions at the dam foundation along the riverbed direction,the design of extending foundation surface excavation area and using consolidating grouting and optimizing structure of dam bottom was introduced,allowing for harmonization of the arch dam and foundation.Three-dimensional(3D)geomechanics model test and fi nite element analysis results indicated that the dam body and foundation have good overload stability and high bearing capacity.The monitoring data showed that the behaviors of dam and foundation correspond with the designed patterns in the construction period and the initial operation period.

The development of super-high collapse resistant casing

Super-high collapse resistant casings were developed by using Ti, Nb and V microalloyed CrMo steel and cross rolling techniques. A transmission electron microscope（TEM） and X-ray diffractometer were used to observe the characteristics of the microstructure. It was found that the （ 111 ） texture and the nano-scale precipitates distribute in a way that is beneficial to the collapse resistance, and the collapse strength of the prepared casing had a measurement, which was approximately 60% higher than the API standard value. A design concept to attain super-high collapse resistance is proposed based on the texture design and microstructure control.

The Heat Treatment Behavior of Super-High Strength Aluminum Alloys by Spray Forming

In order to understand the stress corrosion behavior of super-high strength aluminum alloys by spray forming, different aluminum alloys by different heat treatment was made. The results showed that the alloy with peak aging has the most sensitive stress corrosion cracking, the crack can even be seen using eyes;the alloys with two step aging were better than one step aging alloys, the alloys has not been found stress corrosion cracking.

Effect of super-high pressure on microstructure and mechanical properties of Mg_(97)Zn_(1)Y_(2) alloys

Super-high pressure(SHP)technique plays an increasing role in the fields of materials science and engineering.Herein,the Mg_(97)Zn_(1)Y_(2) alloy was heat-treated under SHP(6 GPa)by cubic-anvil large-volume press with six rams for 2 h in the temperature range of 500–1200℃.The microstructure and mechanical properties were investigated.The results indicated that the as-cast sample consists of α-Mg equiaxed dendrites and continuous lamellar long period stacking ordered(LPSO)phase in grain boundaries.After the SHP treatment,the LPSO phase is gradually replaced by eutectic phase(Mg,Zn)_(3)Y with increasing temperature.The microhardness and strength of sample prepared at 1100℃ under SHP treatment are significantly improved compared with the as-cast one at room temperature.The improved mechanical behaviors are mainly attributed to LPSO phase kink-banding strengthening at low temperature and the precipitation strengthening of a large amount of fine(Mg,Zn)_(3)Y particles at high temperature after SHP treatment.It reveals the SHP is an effective approach to prepare high performance Mg alloys.

Super-High Initial Velocity Mechanism of Bullet Propulsion with Adaptive Pressure-Maintaining Chamber

To deal with the problem that the initial velocity of the bullet is difficult to increase,the research on the super-high initial velocity propulsion in the barrel weapon with an adaptive pressure-maintaining chamber are conducted.Considering the law of gun-powder burning and the flow characteristics of gun-powder gas in multi-chamber,the scheme of super-high initial velocity propulsion with an adaptive pressure-maintaining chamber is designed,the ballistic model of the barrel weapon with super-high velocity bullet propulsion is established.The research results show that the technical scheme can greatly increase the initial velocity of the bullet with the peak pressure keeping nearly the same as the tradition barrel weapon.The research results can provide a theoretical foundation to significantly increase the initial velocity in barrel weapons using solid propellants,and have an important reference value to comprehensively increase the power of the barrel weapons.

高韧性纤维混凝土特性及工程应用

高韧性纤维混凝土具有高强、高韧、高耐久性、良好的环保性能及裂缝无害化分布等特点,能显著改善传统混凝土强而不韧、脆性易裂的根本缺陷。针对影响纤维混凝土性能的主要因素,主要从抗压强度、抗折强度等方面分析其力学性能,并从微观角度探索纤维混凝土中纤维发挥增韧作用的机理及工程应用状况,最后指出了高韧性纤维混凝土研究存在的问题并展望其研究与发展前景。

热定形工艺对高强型聚酯工业丝结构性能的影响

为探究不同热定形温度获得的高强型聚酯工业丝性能差异的内在结构因素,对3种高强型聚酯工业丝的结构性能进行对比。采用小角X射线散射和广角X射线衍射方法对其多尺度微观结构进行研究,结合力学性能及热收缩等结果,明确不同热定形工艺对高强型工业丝结构性能的影响。结果表明:热定形温度主要影响聚酯工业丝非晶区取向和片晶结构;相比于高强中缩(HTMS)和高强(HT)聚酯工业丝,高强低伸型(HTLE)聚酯工业丝的热定形温度低,高倍牵伸产生的伸直非晶区分子链在较低热定形温度下并未及时排入晶格形成结晶,而发生了小幅的回复,导致HTLE聚酯工业丝表现出非晶区取向高、结晶度低、晶粒尺寸小与片层倾斜角较大的结构特点,从而使断裂伸长率最小、初始弹性模量最大、尺寸稳定性差。

精梳工艺对涤粘混纺纱质量的影响

为评价精梳工艺在涤粘混纺纱加工过程中的应用效果,分别采用普梳涤粘混纺工艺与精梳涤粘混纺工艺纺制了混纺比为65/35、50/50、35/65的涤粘混纺纱,测试了两种混纺工艺的纤维条与纱线质量。试验结果表明:与普梳涤粘一并条相比,精梳涤粘条的条干CV值略微降低,棉结、杂质粒数以及16.5 mm以下短绒率大幅减小,纤维上四分位长度微量增长;与普梳涤粘纱相比,精梳涤粘纱的条干CV值与3 mm毛羽数明显降低,棉结、粗节、细节大幅减少,断裂强力有所增加;随着粘胶含量的增加,涤粘混纺纤维条与纱线质量呈现恶化的趋势。认为:精梳工艺能显著提高涤粘混纺纤维条与纱线质量。