改性水溶性高分子粘结剂的制备及性能的研究

动物胶粘结剂是水溶性天然高分子粘结材料,具有无毒无害、可降解等特性,但其也具有在常温下易凝聚、流动性差、型砂强度低等问题,针对这一问题需要对其进行改性处理。在碱解条件下,采用丙三醇、乙醇和糊精对动物胶进行改性处理。试验表明:在碱解过程中,水胶比为8∶5,Na OH加入量为动物胶质量的5%,在改性过程中,选择的改性剂最佳配比(质量比)为:动物胶∶丙三醇∶乙醇∶糊精=100∶10∶10∶10,改性温度为75℃、改性时间为90 min。测得其表面张力值为26.451m N/m、抗压强度达到3.30 MPa,最后通过红外光谱对改性机理进行理论分析,分析认为改性剂丙三醇、乙醇和糊精可与动物胶发生反应。结果证明丙三醇、乙醇和糊精复合改性剂可以降低动物胶表面张力,提高表面润湿性,最终使得砂型强度增大。     

羧甲基壳聚糖接枝甲基丙烯酸共聚物的合成研究

以过硫酸铵为引发剂,将羧甲基壳聚糖与甲基丙烯酸进行接枝共聚,讨论了引发剂浓度、羧甲基壳聚糖浓度、甲基丙烯酸浓度对接枝率和接枝效率的影响,当引发剂浓度为4.5×10-3mol/L,甲基丙烯酸浓度为1.5mol/L,羧甲基壳聚糖浓度为5g/L,在50℃反应2.5h,反应的接枝率和接枝效率较高,并用红外光谱对所得的接枝产物进行了表征。以接枝共聚物为载体制备了红霉素药物的缓释片剂,通过测定药物片剂在磷酸盐缓冲溶液(pH=7.4)中的释放速率,表明药物片剂具有缓释作用。     

氟橡胶/三元乙丙橡胶密封材料的制备及性能研究

氟橡胶(FKM)具有耐高温、耐化学腐蚀以及摩擦因数和表面能较低等特点,是一种在特殊环境有较高应用价值的密封材料,但其弹性和耐寒性能较差、加工性不良,且价格昂贵。采用三元乙丙橡胶(EPDM)与其并用,可在改善低温和加工性能的同时,降低成本。通过万能材料试验机、阿克隆磨耗仪及老化箱考察硫化体系、FKM/EPDM配比及吸酸剂对硫化胶的耐磨、耐腐蚀、耐油等性能的影响。结果表明:采用双硫化体系能获得性能良好的FKM/EP-DM并用硫化胶;当FKM/EPDM并用胶的配比为3∶1,双酚AF质量分数为2.5%,BPP为0.4%,DCP为1.5%,TAIC为4%时,能充分发挥EPDM的优势,FKM的性能得到改善,同时成本降低;高活性氧化镁(吸酸剂)的加入,减少了在硫化过程中大分子的降解,可提高硫化胶的性能,其较佳用量为1.5%。     

成核剂对聚对苯二甲酸乙二醇酯的结晶行为影响

在HAAKE转矩流变仪中进行了聚对苯二甲酸乙二醇酯(PET)和不同类型成核剂的熔融共混,采用差示扫描量热仪(DSC)研究了不同粘度纯PET、纯PBT及添加小分子成核剂、高分子成核剂、复合成核剂的PET非等温结晶过程。通过红外光谱(FTIR)、热台偏光显微镜(POM)和扫描电镜(SEM)对添加成核剂前后PET的结晶形貌进行对比分析。结果表明低粘度PET的结晶能力较中粘度和高粘度的PET结晶能力强,添加成核剂后PET的结晶峰温移向高温、半结晶时间缩短、结晶速率常数增大。其中高分子成核剂、复合成核剂对PET结晶行为改善效果更好,其成核机理为化学成核,但高分子成核剂不会造成PET分子链的降解。     

分散剂用量对悬浮聚合MMA-EA-GMA三元共聚物粒径的影响

以甲基丙烯酸甲酯(MMA),甲基丙烯酸缩水甘油酯(GMA),甲基丙烯酸乙酯(EA)为单体,过氧化苯甲酰(BPO)为引发剂,以聚乙烯醇(PVA)为分散剂,采用悬浮聚合方法合成了MMM-GMA-EA三元共聚物,研究了聚乙烯醇分散剂加入量对MMA-GMA-EA三元共聚物粒径大小的影响。研究结果表明聚乙烯醇加入量为0.3 g时,产物的粒径最小,分布最均匀。     

低温液压油用黏度指数改进剂氢化丁二烯异戊二烯共聚物的合成

该文采用正丁基锂/四氢呋喃/环己烷体系引发丁二烯异戊二烯共聚合得到了丁二烯异戊二烯共聚物(BIR),采用2-乙基己酸镍/三乙基铝催化体系对其加氢,得到了不同微观结构与分子量的氢化丁二烯异戊二烯共聚物(HBIR)。聚合物的分子量及其分布采用凝胶渗透色谱(GPC)表征,微观结构采用1H-NMR表征,热稳定性采用热重分析(TGA)进行表征。将HBIR溶解在150SN中,考察了微观结构和分子量对增稠能力、剪切稳定性和低温启动性的影响,以及与降凝剂的配伍效果。以HBIR为黏度指数改进剂,调配了不同黏度级别的低温液压油,HBIR可使油品的黏度指数有很大的提升,而对油品的倾点几乎无影响。     

EPDM/BIIR共混及其并用胶性能研究

为寻求综合性能优异的新型橡胶密封材料,开展三元乙丙橡胶/溴化丁基橡胶(EPDM/BIIR)共混研究,通过体系优选、配方设计与工艺优化制备EPDM/BIIR并用胶,研究其气体阻隔性、耐老化性、相关力学性能与共混比的关系,并与同类产品进行性能对比.结果表明:EPDM与BIIR共混相容性、共硫化性良好,最佳共混比为70∶30;并用胶耐老化性与同类产品相当,气密性、抗压缩永久变形性优于其他同类产品;二者并用实现了性能优势互补.     

建筑给排水管道橡胶密封圈老化程度测试及密封性能分析

为延长给排水管道橡胶密封圈的使用寿命,通过建筑给排水管道橡胶密封圈老化程度测试,分析其密封性能。以固定质量分数的三元乙丙橡胶、炭黑N115、氧化锌、硬脂酸与不同质量分数的硫磺、防老剂4010NA、促进剂TMTD/NS、增塑剂A为配方材料,制备不同配比的建筑给排水管道三元乙丙橡胶密封圈。采用正交试验法通过在85℃污水介质下,研究不同配方材料添加量对三元乙丙橡胶密封圈老化性能指标的影响,获取三元乙丙橡胶密封圈试件最佳配比;通过对试验管道作漏水检测以及不同热氧老化试验,分析试件的耐老化性能与密封性能。试验结果表明：硫磺、防老剂4010NA、促进剂TMTA、促进剂NS、增塑剂A的配比为0.6∶2.2∶1.8∶1.5∶2时,制备的密封圈试件压缩率指标最高、压缩永久变形指标值最小;热氧老化温度为85,100℃时,经90 d老化,密封圈试件密封性能最突出;热氧老化温度升至115,130℃,分别经17,5 d老化后,其密封性能明显下降;24%压缩率下,管道可承受的最大压力为4 MPa,在该压力下仍能保证管道不漏水。     

IA-HPA-AMPS三元聚合物的合成及其性能研究

以衣康酸(IA)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)以及丙烯酸羟丙酯(HPA)为反应单体,以去离子水为溶剂,过硫酸铵为引发剂,采用溶液聚合的方式合成一种三元聚合物阻垢剂(IA-AMPS-HPA),之后利用红外光谱以及热重分析仪对其结构进行表征,并利用扫描电镜观察水垢晶型的变化.通过考察单体配比、反应温度、反应时间...     

熔盐法制备石墨化碳纳米片

以二氨基马来腈为原料、氯化铁为催化剂前驱体、ZnCl2-KCl为熔盐介质,采用熔盐法制备石墨化碳纳米片,研究了反应温度和熔盐/反应物质量比(盐料比)对产物物相组成、显微结构和石墨化程度的影响。结果表明:随着反应温度的升高和盐料比的增加,产物的石墨化程度增大,片状结构的占比增大;当反应温度为1 000℃、盐料比为40∶1时,制备得到了石墨化碳纳米片,其直径为2~10μm,厚度为30nm。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.