漆酶催化杨梅素对羊毛纱线的低强损染色与功能改性

采用漆酶催化杨梅素生成有色聚合产物,通过吸附或接枝到羊毛纱线上,实现羊毛纱线的染色和功能改性。工艺优化结果为:醋酸盐缓冲液pH 5.0,漆酶浓度20 U/mL,染色时间5 h,染色温度50℃。该染色工艺可使纱线在获得较深颜色的同时,赋予其良好的物理机械性能,染色后纱线断裂强力提升20.7%,断裂伸长下降8.4%,耐磨性和耐碱溶性也有一定提升。同时,染色后纱线具有一定的功能性,抗氧化性能和抗菌性能大幅提升,对ABTS+·自由基的清除率为71.77%,对大肠埃希菌和金黄葡萄球菌的抑菌率分别达到90.82%和94.08%。

锦纶66原丝采样和测试方法对帘线强损值计算的影响

研究锦纶66原丝不同取样方法和测试方法对捻织工序帘线强损值计算结果的影响.通过研究锦纶66原丝筒子在下机取样、平衡后取样、流入捻织后随机取样等三种取样方法和原丝加捻、不加捻两种测试条件下的测试结果对捻织计算强损值的影响,可以看出只有正量测试的结果才有利于试验的研究.

基于菠萝蛋白酶的羊毛生物酶法防毡缩整理

针对微生物蛋白酶在羊毛酶法防毡缩整理过程中易造成羊毛纤维损伤的问题,本文采用植物蛋白酶(菠萝蛋白酶)与预处理结合的工艺对羊毛织物进行防毡缩整理。结果表明,菠萝蛋白酶在预处理的基础上能够有效改善羊毛织物的防毡缩性能,整理后的织物毡缩率为5.29%,强力损失率为4.10%。通过扫描电镜、亚甲基蓝着色等表征方法综合判断,菠萝蛋白酶作用于羊毛鳞片层,进而实现在降低羊毛织物毡缩率的同时将强力损失率控制在一个较小的水平。

Damage and fracture behavior and spatio-temporal evolution of acoustic emission of sandstone before and after laser radiation

Laser technology holds significant promise for enhancing rock-breaking efficiency.Experimental investigations were carried out on sandstone subjected to laser radiation,aiming to elucidate its response mechanism to such radiation.The uniaxial compressive strength of sandstone notably decreases by 22.1%–54.7%following exposure to a 750 W laser for 30 s,indicating a substantial weakening effect.Furthermore,the elastic modulus and Poisson ratio of sandstone exhibit an average decrease of 33.7%and 25.9%,respectively.Simultaneously,laser radiation reduces the brittleness of sandstone,increases the dissipated energy proportion,and shifts the failure mode from tensile to tension-shear composite failure.Following laser radiation,both the number and energy of acoustic emission events in the sandstone register a substantial increase,with a more dispersed distribution of these events.In summary,laser radiation induces notable damage to the mechanical properties of sandstone,leading to a substantial decrease in elastic energy storage capacity.Laser rock breaking technology is expected to be applied in hard rock breaking engineering to significantly reduce the difficulty of rock breaking and improve rock breaking efficiency.

黄麻/聚丙烯针刺毡的阻燃性能

采用协效复合型阻燃剂FR-PN-G对黄麻/聚丙烯复合毡进行阻燃整理,利用正交试验方法优化阻燃剂质量浓度、浸渍时间、浸轧次数等阻燃工艺参数,得出最佳阻燃工艺参数:阻燃剂质量浓度为450 g/L,浸渍时间为20 min,浸轧次数为2次。在此工艺参数下进行阻燃整理,测得黄麻/聚丙烯复合纤维毡的极限氧指数为35.2%,炭长40 mm,续燃时间0 min,阴燃时间0 min,拉伸强度24.95 MPa,弯曲强度30.27 MPa,表明阻燃综合效果最佳。

浅谈涤纶仿真丝绸的加工

本文概述了涤纶仿真丝绸的发展、种类及原料选择.分析了涤纶仿真丝绸加工的重要环节——碱减量处理的原理及工艺,说明了有关质量检测方法.

INTERFACE DAMAGE ANALYSIS OF FIBER REINFORCED COMPOSITES WITH DUCTILE MATRIX

A cohesive zone model is employed to simulate the fiber/matrix interface damage of composites with ductile matrix. The study is carried out to investigate the dependence of the interface damage and the composite tensile strength on the micro parameters of the composite. These parameters contain fiber packing pattern, fiber volume fraction, and the modulus ratio of the fiber to the matrix. The investigation reveals that though the high fiber vo lume fraction, the high fiber′s modulus and the square fiber packing can supply strong reinforcement to the composite, the interface damage is susceptible in these cases. The tensile strength of the composite is dominated by the interface strength when the interface debonding occurs.

Preparation and mechanical properties of in situ Al_2O_3/Al composites by adding NH_4AlO(OH)HCO_3

Aluminium matrix composite reinforced by Al2O3 particles was produced by adding NH4AlO（OH）HCO3 into molten aluminum.The mechanical properties and wear behavior of the as-fabricated composites were studied.The results show that during stirring γ-Al2O3 particles were formed via decomposition reaction of NH4AlO（OH）HCO3,and the distribution of Al2O3 particles is more uniform in the matrix aluminum than directly added Al2O3 into molten aluminum.The density and the hardness values of the as-fabricated composites increase with increasing the particle volume fraction,while the tensile strength of the composites decreases with increasing the volume fraction of the Al2O3 particles.The wear rate of the composites decreases with increasing the volume fraction of the particle and loading.The in situ formed Al2O3/Al composite by adding NH4AlO（OH）HCO3 shows more superior mechanical and wear behaviors than that prepared by directly adding Al2O3 particles.

A damage constitutive model of rock-like materials containing a single crack under the action of chemical corrosion and uniaxial compression

To describe the deformation and strength characteristics of the corroded rock-like specimens containing a single crack under uniaxial compression,a damage constitutive model combining hydro-chemical damage with coupling damage of micro-flaws and macro-cracks is proposed.Firstly,based on phenomenological theory,the damage variable of the rock-like specimens subjected to water environment erosion and chemical corrosion is obtained.Secondly,a coupled damage variable for cracked rock-like specimens is derived based on the Lemaitre strain equivalence hypothesis,which combines the Weibull statistical damage model for micro-flaws and the fracture mechanics model for a macro single crack.Then,considering the residual strength characteristics of the rock-like materials,the damage variable is modified by introducing the correction coefficient,and the damage constitutive model of the corroded rock-like specimens with a single crack under uniaxial compression is established.The model is verified by comparing the experimental stress−strain curves,and the results are in good agreement with those provided in the literature.Finally,the correction coefficient of the damage variable proposed in this paper is discussed.The damage constitutive model developed in this paper provides an effective method to describe the stress−strain relationship and residual strength characteristics of the corroded rock-like specimens with a single crack under uniaxial compression.

Stabilization of saline silty sand using lime and micro silica

Many construction and post-construction problems have been reported in the literature when saline soils have been used without understanding of their abnormal behavior,especially their inferior bearing capacity in the natural condition.The strength of these soils further decreases on soaking.Saline soil deposits cover extensive areas in central Iran and are associated with geotechnical problems such as excessive differential settlement,susceptibility to strength loss and collapse upon wetting.Because of these characteristics,some of the roads constructed on saline soils in Taleghan area have exhibited deterioration in the form of raveling,cracking and landslides.The main objective of this work is to improve the load-bearing capacity of pavements constructed on Taleghan saline soils using lime and micro silica.Soil samples from Hashtgerd-Taleghan road were collected and tested for improving their properties using lime and micro silica at different dosages ranging from 0 to 6%.The load-bearing capacity of stabilized soil mixtures was evaluated using California Bearing Ratio(CBR) and unconfined compressive strength tests.The test results indicate that the lime improves the performance of soil significantly.The addition of 2% lime with 3% micro silica has satisfied the strength-deformation requirements.Therefore,improved soil can be used as a good subbase in flexible pavements.

Vibration analysis of maglev three-span continuous guideway considering control system

The dynamic interaction between maglev vehicle and three-span continuous guideway is discussed. With the consideration of control system, the dynamic interaction model has been developed. Numerical simulation has been performed to study dynamic characteristics of the guideway. The results show that bending rigidity, vehicle speed, span ratio and primary frequency all have important influences on the dynamic characteristics of the guideway and there is no distinct trend towards resonance vibration when fl/（v/l） equals 1.0. The definite way is to control impact coefficient and acceleration of the guideway. The conclusions can serve the design of high-speed maglev three-span continuous guideway.

Comparison of wear behaviour of LM13 Al−Si alloy based composites reinforced with synthetic(B_(4)C)and natural(ilmenite)ceramic particles

Dry sliding wear behaviour of stir-cast aluminium matrix composites(AMCs)containing LM13 alloy as matrix and ceramic particles as reinforcement was investigated.Two different ceramic particle reinforcements were used separately:synthetic ceramic particles(B_(4)C),and natural ceramic particles(ilmenite).Optical micrographs showed uniform dispersion of reinforced particles in the matrix material.Reinforced particles refined the grain size of eutectic silicon and changed its morphology to globular type.B_(4)C reinforced composites(BRCs)showed maximum improvement in hardness of AMCs.Ilmenite reinforced composites(IRCs)showed maximum reduction in coefficient of friction values due to strong matrix−reinforcement interfacial bonding caused by the formation of interfacial compounds.Dry sliding wear behaviour of composites was significantly improved as compared to base alloy.The low density and high hardness of B_(4)C particles resulted in high dislocation density around filler particles in BRCs.On the other hand,the low thermal conductivity of ilmenite particles resulted in early oxidation and formation of a tribo-layer on surface of IRCs.So,both types of reinforcements led to the improvement in wear properties of AMCs,though the mechanisms involved were very different.Thus,the low-cost ilmenite particles can be used as alternative fillers to the high-cost B_(4)C particles for processing of wear resistant composites.

Dry sliding wear behavior of stir cast AA6061-T6/AlN_p composite

The dry sliding wear behavior of AA6061 matrix composite reinforced with aluminium nitride particles（AlN） produced by stir casting process was investigated. A regression model was developed to predict the wear rate of the prepared composite. A four-factor, five-level central composite rotatable design matrix was used to minimize the number of experimental runs. The factors considered in this study were sliding velocity, sliding distance, normal load and mass fraction of AlN reinforcement in the matrix. The developed regression model was validated by statistical software SYSTAT 12 and statistical tools such as analysis of variance（ANOVA） and student＇s t test. It was found that the developed regression model could be effectively used to predict the wear rate at 95% confidence level. The influence of these factors on wear rate of AA6061/AlNp composite was analyzed using the developed regression model and predicted trends were discussed with the aid of worn surface morphologies. The regression model indicated that the wear rate of cast AA6061/AlNp composite decreased with an increase in the mass fraction of AlN and increased with an increase of the sliding velocity, sliding distance and normal load acting on the composite specimen.

Theoretical analysis of characteristics of acoustic emission in rock failure based on statistical damage mechanics

Based on statistical damage mechanics,the constitutive model of a rock underthree-dimensional stress was established by the law that the statistical strength of rockmicro-element obeys Weibull distribution.The acoustic emission (AE) evolution model ofrock failure was put forward according to the view that rock damage and AE were consistent.Moreover,in the failure process of rock under three-dimensional stress,the change inrelationship between stress condition parameter and the characteristic parameters of AE,such as the event number and its change rate,were studied.Also,the rock AE characteristicunder uniaxial compression was analyzed in theory and verified with examples.Theresults indicate that the cumulative event number and change rate of AE in rock failure aredetermined by stress state parameter F.Along with the gradual increase of F,first the cumulativeevent number increases gradually,then rapidly,and then slowly after the stresspeak.The form of change rate of an event by increasing F is consistent with the distributionform of rock micro-element strength.The model explained the phenomenon that a relativelyquiet period of AE appears before rock rupture that is observed by many researchersin experiments.Verification examples indicate that the AE evolution model is consistentwith the test results,so the model is reasonable and correct.

Improving impact wear resistance of Ti-6Al-4V alloy treated by laser shock peening

The effects of laser shock peening (LSP) on the impact wear behavior of Ti-6Al-4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were studied. During the impact wear test, the energy absorption, impact force, wear contact time and wear mechanism of all the test samples were investigated in terms of the influence of the impact kinetic energy. The results showed that microhardness, elastic modulus and residual compressive stress of the treated samples were markedly improved. The wear resistances of both treated samples were highly improved after LSP, and a higher pulse energy corresponded to a more obvious effect. Besides, the wear in all test samples involved a combination of abrasive and oxidation wear and fatigue spalling.

Damage Pattern Recognition of Spatially Distributed Slope Damages and Rainfall Using Optimal GIS Mesh Dimensions

Damage assessment for slopes using geographical information system(GIS) has been actively carried out by researchers working on several government organizations and research institutes in Korea. In this study, 596 slope damages were examined to identify the types of damage associated with dip angles, dip directions, and heavy rainfall resulting from typhoons in South Korea. Heavy rainfall of 100 mm to 300 mm resulted in 80% at the investigated slope damages. A GIS database was developed for highways, rainfall, soil or rock geometry, and types of damage. A grid of rainfall intensity was generated from the records of maximum daily rainfall. Contours for slope damages and heavy rainfall using optimal GIS mesh dimensions were generated to visualize damage patterns and show substantially strong correlation of rainfall with slope damages. The combination of remote sensing with the GIS pattern recognition process described in this work are being expanded for a new generation of emergency response and rapid decision support systems.

Application of analytical hierarchy process to selection of primary crusher

Selection of crusher required a great deal of design based on the mining plan and operation input. Selection of the best primary crusher from all of available primary crushers is a Multi-Criterion Decision Making （MCDM） problem, in this paper, the Analytical Hierarchy Process （AHP） method was used to selection of the best primary crusher for Golegohar Iron Mine in Iran. For this reason, gyratory, double toggle jaw, single toggle jaw, high speed roll crusher, low speed sizer, impactor, hammer mill and feeder breaker crushers were considered as alternatives and capacity, feed size, product size, rock compressive strength, abrasion index and mobility of crusher were considered as criteria. As a result of our study, the gyvratory crusher was offered as the best primary crusher for the studied mine.

Effect of TiO_2 and ZrO_2 reinforcements on properties of Al_2O_3 coatings fabricated by thermal flame spraying

The alumina composite coatings reinforced with 25% ZrO2 （denoted as AZ-25） and 3% TiO2 （denoted as AT-3） were deposited on low carbon steel using a thermal flame spraying. The microstructure, phase composition, microhardness and tribological properties of the coatings were investigated. The XRD results of the coatings reinforced by TiO2 （AT-3） revealed the presence of α-Al2O3 phase as matrix and new metastable phases of α-Al2O3 and α-Al2O3. However, the coatings reinforced by ZrO2 （AZ-25） consist of α-Al2O3 as matrix, q-ZrO2 and m-ZrO2. In most studied conditions, the AT-3 coating displays a better tribological performance, i.e., lower coefficient of frictions and wear rates, than the AZ-25 coating. It was also found that the microhardness of the coatings was decreased with the reinforcement of ZrO2 and increased with TiO2.

Dynamic tensile strength and failure mechanisms of thermally treated sandstone under dry and water-saturated conditions

To study the tensile strength and failure mechanisms of rock with hydro-thermal coupling damage under different loading rates,a series of static and dynamic splitting tests were conducted on thermally treated sandstone under dry and water-saturated conditions.Experimental results showed that high temperatures effectively weakened the tensile strength of sandstone specimens,and the P-wave velocity declined with increasing temperature.Overall,thermal damage of rock increased gradually with increasing temperature,but obvious negative damage appeared at the temperature of 100℃.The water-saturated sandstone specimens had lower indirect tensile strength than the dry ones,which indicated that water-rock interaction led to secondary damage in heat-treated rock.Under both dry and water-saturated conditions,the dynamic tensile strength of sandstone increased with the increase of strain rate.The water-saturated rock specimens showed stronger rate dependence than the dry ones,but the loading rate sensitivity of thermally treated rock decreased with increasing treatment temperature.With the help of scanning electron microscopy technology,the thermal fractures of rock,caused by extreme temperature,were analyzed.Hydro-physical mechanisms of sandstone under different loading rate conditions after heat treatment were further discussed.

Synergistic regulation of current-carrying wear performance of resin matrix carbon brush composites with tungsten copper composite powder

Resin matrix carbon brush composites(RMCBCs)are critical materials for high-powered electric tools.However,effectively improving their wear resistance and heat dissipation remains a challenge.RMCBCs prepared with flake graphite powders that were evenly loaded with tungsten copper composite powder(RMCBCs-W@Cu)exhibited a low wear rate of 1.63 mm^(3)/h,exhibiting 48.6%reduction in the wear rate relative to RCMBCs without additives(RMCBCs-0).In addition,RMCBCs-W@Cu achieved a low friction coefficient of 0.243 and low electric spark grade.These findings indicate that tungsten copper composite powders provide particle reinforcement and generate a gradation effect for the epoxy resin(i.e.,connecting phase)in RMCBCs,which weakens the wear of RMCBCs caused by fatigue under a cyclic current-carrying wear.