CAN网络控制系统的网络时延分析与检测

针对CAN总线的实时特性,分析CAN网络控制系统的网络时延模型.结合CAN报文延迟时间在错误帧影响下的数学模型,分析了影响报文延迟时间的主要因素.通过所设计的CAN网络实验平台,在线检测CAN报文延迟时间,分析报文实际传输时延与理论分析的差异.实验表明错误帧及网络负载是造成较大网络时延的直接原因,进而验证了网络时延分析的有效性.     

网络控制系统在线时延预估策略与实现

分析网络时延的产生以及影响其取值规律的原因,提出网络时延在线预估法以预估将来时刻可能产生的控制器与执行器之间的时延.在CAN bus网络控制实验平台上对该预估法的有效性进行验证,实验结果表明,该方法准确地预估出下一时刻网络时延的大小,并且基于预估到的网络时延设计的控制器很好地保证了控制系统的稳定性.     

基于双轨图的网络控制系统稳定性分析

网络控制系统中网络时延的引入,影响系统性能,甚至引起不稳定.为了便于分析网络时延对控制系统稳定性的影响,采用简单的比例控制器,利用双轨图,分析了单摆网络控制系统存在网络时延时的稳定性问题,给出了不稳定范围和稳定范围.同时也给出了单摆网络控制系统稳定性与阻尼系数之间的关系.结果显示利用双轨图进行有时间延迟的网络控制系统稳...     

CAN网络控制系统网络时延分析及其控制

通过反复实验,捕获了大量由于CAN网络而引起的网络时延.通过对这些时延数据分析,归纳出基于CAN网络的网络时延统计特性.利用得到的网络时延统计特性,设计相应的控制系统.实验结果证明,在不同的网络负载下,网络控制系统设计需要采用不同的控制算法.尤其是在网络负载很重的情况下,现有的控制器设计已经不能保证系统的稳定性.     

尼龙基MCA母粒的制备及其在阻燃尼龙的应用

针对三聚氰胺氰尿酸盐(MCA)粉体对尼龙(PA)进行阻燃改性时,MCA分散性差,材料阻燃性能不稳定的问题,运用特殊的包覆工艺成功制得了PA基MCA母粒。将制得的MCA母粒及MCA粉体分别与PA6或PA66共混挤出,制得阻燃PA材料。对比分析了MCA母粒及MCA粉体阻燃PA6或PA66的垂直燃烧性能和力学性能。结果表明,与MCA粉体相比,MCA母粒可在MCA含量较低的情况下使厚度为0.8 mm及1.6 mm的阻燃PA6或PA66试样的垂直燃烧等级达到V–0级。MCA母粒及粉体对阻燃PA6的弯曲强度和PA66的拉伸强度影响很小,MCA母粒阻燃PA6的拉伸强度较粉体阻燃的高,而阻燃PA66的弯曲强度低;MCA母粒使阻燃PA的缺口冲击强度降低,而MCA粉体对PA的缺口冲击强度影响较小,当MCA含量较低时,MCA母粒阻燃PA的缺口冲击强度明显高于MCA粉体阻燃的PA。制备的MCA阻燃母粒对PA的阻燃效果不受黑色母料的影响,且具有较好的阻燃稳定性。     

长碳链聚酰胺改性聚酰胺6的进展

长碳链聚酰胺的高柔性链段可以显著改善短链聚酰胺6(PA6)链段柔性，同时提高了其抗冲击强度，降低了其熔点及吸水性等，因此，采用PA11、PA12或PA1010改性PA6仍为该领域近年来的研究热点。虽然长碳链聚酰胺在改善PA6的力学性能及加工性能等方面的效果显著，但是，由于分子链柔性、氢键形成能力及结晶能力的影响，改性效果并不随长碳链含量的增加而提高。因此，详细地分析了高柔性分子链对改性PA6的链段与结构的影响，综述了不同的长碳链聚酰胺种类、成分比例及改性方法对改性PA6的力学性能、熔点、结晶性能及吸水性等性能的影响。最后，对该领域中亟待解决的问题进行了总结，并且对未来的发展提出了方向及建议。     

汽车技术状态远程监测诊断的数据传输研究与实验

论文在说明数据传输问题对实施汽车技术状态远程监测诊断工作的重要意义之后,分析了GSM网的数据传输特性,以及GSM对TCPAP数据传输特性的影响.在此基础上,论文提出了数据传输时延测试实验方案及测试方法,概述了相关时延测试实验.最后,论文对数据传榆时延测试结果及系统传输能力展开分析,并获得相关结论.     

热老化时间对PA66动态力学性能影响的研究

用动态力学热机械分析(DMA)仪研究了热老化时间对PA66玻璃化转变温度、储能柔量及表观活化能的影响,并分析了产生这些影响的原因。通过试样动态力学性能参数和活化能的突变点确定了PA66的临界失效时间,依据所得的临界失效时间和活化能,以及动态力学性能得到的寿命方程预估了PA66在25℃下的贮存期为40.9年。     

PA6/LiC1复合材料结构分析与性能研究

采用熔融共混挤出的方法,制备了尼龙(PA)6/LiCl复合材料,研究了不同含量的LiC1对PA6的结晶结构及性能的影响.傅立叶变换红外光谱、差示扫描量热、X射线衍射分析及力学性能测试结果表明,LiC1中“+和PA6间产生了络合作用,破坏了PA6中原有的氢键,降低了PA6的分子链的规整排列,但该络合作用使PA6分子链间产...     

改性纤维素纳米晶对聚酰胺6结晶行为的影响

通过表面基团反应制备了异氰酸酯改性纤维素纳米晶（IPDI?CNC),将其与聚酰胺6（PA6）共混后研究了有机纳米晶对PA6结晶行为的影响。利用差示扫描量热仪（DSC）对比分析了纤维素纳米晶（CNC）和IPDI?CNC对PA6的结晶度、结晶动力学参数及结晶速率的影响。结果表明,由于IPDI的引入,IPDI?CNC在PA6中的分散性更好,可以有效提高PA6的结晶度;采用 Jeziorny法研究非等温结晶过程,发现IPDI?CNC起到了异相成核作用,提高了PA6的结晶速度和结晶度;由于PA6的结晶能力提高了,IPDI?CNC的加入使PA6的吸水率降低了71.4 %。     

毛毛虫形粗旦仿毛锦纶6纤维的生产工艺

对毛毛虫形粗旦仿毛锦纶6的生产工艺进行了研究分析,发现合理控制纺丝速度、纺丝温度、侧吹风、热辊温度和拉伸比等工艺参数,改进上油方式,可以生产出物性指标良好,并具有较好仿毛手感的粗旦仿毛锦纶6FDY。试验表明:纺速在4000~4300m/min,拉伸比1.1~1.3,热拉伸温度150~170℃,侧吹风速0.10~0.18m/s,下调上油位置,延缓上油时间,可以生产出外观好、染色均匀、性能指标好、仿毛手感好的粗旦仿毛锦纶6全拉伸丝。     

挤出工艺对长碳链尼龙管断裂伸长率的影响

通过挤出工艺生产长碳链尼龙(PA)11管,并采用火焰热处理方式对PA11管进行后处理,借助拉伸试验设备对PA11管的断裂伸长率进行评价。研究了不同的挤出模具温度(模温)、挤出速度、冷却水温和火焰热处理强度等工艺参数对PA11管断裂伸长率的影响。结果表明,PA11管的断裂伸长率随着模温和火焰热处理强度的升高呈现先升高后降低的趋势,随着挤出速度和冷却水温的降低而升高。生产PA11管最佳的工艺参数为模温235℃、挤出速度25 m/min、冷却水温20℃、火焰热处理强度40%,此时PA11管的断裂伸长率达到219%,拉伸后试样表面的“橘皮状”缺陷消失。     

尼龙6/丙烯酸酯橡胶热塑性弹性体非等温结晶动力学

采用动态硫化法制备尼龙6/丙烯酸酯橡胶热塑性弹性体(PA6/ACM TPE),通过差示扫描量热仪研究了PA6和PA6/ACM TPE在5种不同冷却速率下的结晶过程,并分别用Jezirony法、Ozawa法以及Mo法分析了PA6和PA6/ACM TPE的非等温结晶动力学.结果显示,冷却速率越大,PA6和PA6/ACM T...     

神经元网络技术方法研究PET高速纺丝过程中的细颈点

首次将神经元网络技术运用于ＰＥＴ高速纺丝细颈点的研究中,同时比较了神经元网络预测结果与文献报导数据。并对神经元网络方法和数学模拟方法进行讨论,分析了两种方法的优缺点,分“互补法”的建立奠定了基础。     

Study of the properties of compatibilized ABS/PA6 blends using response surface methodology

Styrene‐(maleic anhydride) copolymer (SMA) compatibilized blends of acrylonitrile‐butadiene rubber (ABS) and polyamide 6 (PA6) with a variety of compositions and compatibilizer levels were prepared at various screw speeds in a corotating twin screw extruder. A Box–Behnken model for three variables, with three levels, was chosen as an experimental design, and the mechanical properties of the blends were considered as the responses. Each response was analyzed and formulated versus the considered factors by the use of response surface methodology. Impact resistance increased with increased SMA concentration and reduced screw speed. In compatibilized samples, with an increase in PA6 content, higher impact resistance was observed. Increasing PA6 content and SMA concentration, as well as decreasing screw speed, gave improvements in both tensile and flexural strengths. In each case, all of the correlations among factors were studied. Grafting of SMA was proved by detecting the graft copolymer (SMA‐PA6) formed through extraction in formic acid and FTIR spectroscopy. Compared with uncompatibilized blends, compatibilized samples displayed more uniform and finer particle sizes, thereby proving the compatibilizing effect of the graft copolymer. The asymmetry trend in dispersed particle size before and after the phase inversion became more differentiated in the presence of the compatibilizer. Adding SMA lowered the phase inversion composition (based on PA6), whereas higher screw speed increased it. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

新型快速固化环氧树脂胶粘剂的制备及性能

以己二酸、多胺(如二乙烯三胺、三乙烯四胺或多乙烯多胺等)为原料,采用熔融缩聚法合成了3种低黏度、低毒性且可室温固化的环氧树脂(EP)胶粘剂用聚酰胺固化剂(PA1、PA2或PA3)。探讨了固化剂含量对EP胶粘剂的固化速率和粘接性能等影响,并采用单因素试验法优选出EP/固化剂的最佳配比。结果表明:EP胶粘剂的固化速率和剥离强度依次为EP/PA1胶粘剂>EP/PA2胶粘剂>EP/PA3胶粘剂;当m(PA1):m(EP)=0.6:1.0、w(促进剂)=1.0%(相对于EP质量而言)、固化温度为80℃和固化时间为60min时,相应胶粘剂的适用期较长,并且加热后能快速固化,而且用该胶粘剂制备的包封膜经处理后,其综合性能良好,可满足柔性印刷电路板(FPC)的生产要求。     

Thermal properties and surface energy characteristics of interpenetrating polyacrylate and polybenzoxazine networks

We have prepared semi-interpenetrating polyacrylate networks (PA/BA-m s-IPNs) through rapid photopolymerization of a triacrylate monomer (TMPTA) in the presence of a photoinitiator (I184), a tetramercaptane transfer agent (4SH), and N-methyl-bisbenzoxazine (BA-m). Next, we prepared novel fully interpenetrating polyacrylate (PA) and polybenzoxazine (PBZ) networks (PA/PBZ f-IPNs) through thermal polymerization of the BA-m monomer at 180 °C for 4 h. For the PA/BA-m s-IPNs, the BA-m monomers can be frozen and dispersed in the UV-cured PA network within 5 min to inhibit macrophase separation. After thermal polymerization, the phenol units of the ring-opened PBZ segments can form a hydrogen-bonding interface with the carbonyl groups to improve the compatibility between the PBZ microdomains and the PA networks. From an analysis using Kissinger's method, the non-isothermal kinetics of the thermal polymerization for the PA/BA-m s-IPNs indicate that an increase in the PA content increased the steric hindrance of PBZ polymerization. We used DSC, TGA, and contact angle analyses to determine the glass transition temperature, thermal stability, and surface free energy, respectively, of the PA/PBZ f-IPNs. The thermal stability and surface free energy of these PA/PBZ f-IPNs display linear relationships with respect to the PBZ content.     

单入双出的模糊预测协调控制在篦冷机系统中的应用研究

针对水泥回转窑的工艺特点，研究了适合大惯性，大滞后等特点的典型工业对象的模糊预测控制算法，并提出了一种解决系统输出多于输入的协调控制问题的方法，以篦冷机系统为对象的仿真结果表明该算法具有很好的快速性和鲁棒性，可在模糊失配很严重的情况下依然保护良好的控制特性，并能充分利用系统信息，增强算法的抗干扰能力及跟踪特性。该方法算法简捷，易于工程实现。     

Effects of microcompounding process parameters on the properties of ABS/polyamide‐6 blends based nanocomposites

Melt intercalation method was applied to produce acrylonitrile‐butadiene‐styrene/polyamide‐6 (ABS/PA6) blends based organoclay nanocomposites using a conical twin‐screw microcompounder. The blend was compatibilized using a maleated olefinic copolymer. The effects of microcompounding conditions such as screw speed, screw rotation‐mode (co‐ or counter‐), and material parameters such as blend composition and clay loading level on the morphology of the blends, dispersibility of nanoparticles, and mechanical properties were investigated. Furthermore, corotating screws were modified to achieve elongational flow which is efficient for obtaining dispersive mixing. The morphology was examined by SEM analysis after preferential extraction of the minor phase. Subsequently, the SEM micrographs were quantitatively analyzed using image analyzer software. The morphology of the blends indicated that processing with counter‐rotation at a given screw speed yielded coarser morphology than that of processed with corotation. X‐ray diffraction analysis showed that highest level of exfoliation is observed with increasing PA6 content, at 200 rpm of screw speed and in corotation mode. Also, the effects of screw speed, screw rotation mode, and screw modification were discussed in terms of XRD responses of the nanocomposites. The aspect ratio of the clay particles which were measured by performing image analysis on TEM micrographs exhibited a variation with processing conditions and they are in accordance with the modulus of the nanocomposites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008