光氧老化对聚丙烯长丝蠕变行为的影响

分别在室内环境及人工加速老化条件下对聚丙烯长丝进行恒定载荷作用下的蠕变实验，在同样的外载荷作用下，受到紫外辐射的作用而发生光氧老化的聚丙烯长丝，其蠕变速率系数有所增大；恒定载荷越大，紫外辐射对材料蠕变的影响越明显；有紫外辐射情况下，恒定载荷大小对蠕变的影响也会变得明显。对不同蠕变时间的聚丙烯长丝进行强力和粘度测试，观察其蠕变过程中性能的变化情况，发现断裂强力和相对分子质量均有所降低，说明在紫外辐射作用下，材料发生光氧老化反应，大分子的降解使微观结构发生改变，导致断裂强力及蠕变行为的变化。     

盛装打扮的黑嘴松鸡

黑嘴松鸡又名细嘴松鸡,是国家一级重点保护动物,是大兴安岭汗马自然保护区内的旗舰物种,对大众具有特别号召力和吸引力,可促进人们对动物保护的关注,可说是地区保育的主题物种.每年的四五月份,在汗马自然保护区里都会上演几十甚至上百只雄性黑嘴松鸡聚集一处,向雌性黑嘴松鸡献舞示爱的好戏.拍摄黑嘴松鸡求偶的精彩照片需要付出艰辛的努力.2014年4月18日凌晨两点,我们蹲守在保护区野外,陪伴我们的只有原始的落叶松林和满天繁星,偶尔能听见狍子、驼鹿、乌林鹗和棕熊的叫声,北噪鸦、黑啄木鸟和紫貂也会在头上或身边倏地掠过.     

项目式数学在程序设计中的应用

传统的程序设计课程的教学存在语句语法过细过多、忽视基本问题求解过程、算法意识薄弱等问题,项目式教学通过一些趣味性的实际问题的求解来贯穿各个知识点,抓住主线,突出基本概念与方法,重点放在思路、算法、编程构思与程序实现上,可以很好地激发学生学习兴趣,提高教学效率和质量.     

网络环境下的自主学习探究

结合教学实践主要研究网络环境下的自主学习新模式,从其理论依据、培养目标、基本模式、存在优势、对教学构成要素的要求、评价办法及注意事项等方面对网络环境下的自主学习进行了分析和探索。     

Psychometric Properties of Geometrical Texture Features for Tactile Roughness Sensation of Fabric Surfaces

The lack of understanding of the psychometric properties on the basic texture features forming tactile texture sense hinders the development of haptic rendering technology of textiles. The differential threshold and Weber fraction were investigated for a deep understanding of how surface texture features of fabrics affect the perceived roughness sensation by the constant stimulus method and the paired comparison method. The results showed that the differential threshold for the mean deviation of surface profile was0. 86 μm,and that the differential threshold of texture spatial period(TSP) was 2. 48 mm. And also,the difference thresholds and Weber fraction were affected by the reference stimulus intensity. As there is a significant interaction between four extracted texture feature indexes,any of the indexes alone cannot represent roughness sensation of fabrics.     

浅析市场营销中的消费者行为分析

消费者市场的购买是最终市场的购买,意味着商品价值和使用价值的最终实现。市场营销学研究消费者市场,核心是研究消费者的购买行为,即消费者购买商品的活动和与这种活动有关的决策过程,购买行为是与购买商品有关的各种可见的活动,而这些活动必须受消费者心理活动的支配,并受消费者个人特性和社会文化因素的影响,是这些复杂的因素相互制约和作用的结果。     

不同光源条件下PVC涂层膜材料的光氧老化性能

以聚氯乙烯(PVC)涂层膜材料为研究对象,分别采用UVB313和UVA340型紫外灯管为光源进行人工加速老化试验,研究其光氧老化过程.对老化过程中试样的拉伸性能进行测试,并进行红外光谱和紫外光谱分析,以探究其光氧老化动力学过程.试验结果表明:两种光源条件下试样的光氧老化机制没有发生变化,但当累积紫外辐射能相同时,试样的老化程度并不一致,这是由两种光源的发光光谱不同造成的,因此,互易定律不适用于PVC涂层膜材料寿命预测模型的建立.根据两光源发光光谱的不同,引入有效紫外辐射的概念,依据改进的Schwarzschild定律建立了不同光源条件下PVC涂层膜材料老化结果的相关性.     

Anthropomorphic Classification of Tactile Qualities of Woven Fabrics Based on Skin/Textile Friction-Induced Vibrations

The common method classifying tactile qualities of fabrics is indirectly based on their difference of purely mechanical and physical properties. When human skin slides across fabric surfaces, the friction interaction between fabrics and skin will occur and trigger the cutaneouS tactile receptors, which are responsible for perceived tactile sensation. By the extracted features from friction- induced vibration signals, this paper presents an anthropomorphic classification method classifying tactile qualities of fabrics. The friction-induced vibration signals are recorded by a three-axis accelerator sensor, and the entice testing procedure is conducted in an anthropomorphic way to obtain vibration signals. The fast Fourier transform （FFT） is applied to analyzing the recoded signals, and then the classification features are extracted from the FFT data by the neurophysiological properties of tactile receptors. The extracted features are used to classify fabric samples by the softness sensation and the roughness sensation, respectively, and the classification performance is checked by a comparison with those in a sensory evaluation procedure. The results showed that the anthropomorphic objective classification method was precise and efficient to clarify tactile qualities of woven fabrics.     

Effects of Polyethylene Oxide Concentration on the Size of Beads in Electrospun Beaded Nanofibers

Embedding particle drugs in beaded nanofibers by electrospinning has been shown a potential approach to control drug release in tissue engineering. The bead size is one of the critical parameters in controlling the drug release rate. In this study,the relationship between polymer concentration and beads size was investigated. Aqueous polyethylene oxide（ PEO） solutions with different concentrations were prepared to obtain various beaded nanofibers by electrospnning. Optical microscope and scanning electron microscope（ SEM） were used to observe the variation tendency of bead size. With an increase in the polymer concentration,the diameter of fibers between beads became bigger,while the fiber uniformity improved. In addition, the polymer concentration influenced the distribution of bead diameter. Higher polymer concentration would reduce the possibility of small-sized beads formation and improve the uniformity of bead diameter. The study provides a possible way to control the size of beads,which is helpful for further research on the control of particle drug release.     

高可用集群中TCP连接同步策略的研究

在分析比较了基于TCP连接的各种高可用方案中同步策略的基础上,提出了一种“混合式”的同步策略,该策略对输入流采用集中同步的方式,主服务器复制转发TCP连接建立过程中的初始序列号ISN给服务端的其他节点,来保证服务端所有节点与客户端成功进行三次握手并建立连接,对输入流采用集中同步简化了设置和实现的复杂度;对输出流采用后台同步的方式,该方式通过修改TCP协议栈的接收缓存来保存用于同步的必要信息,以保证输出流消息的后台一致性,提高了服务端在高负荷环境下的性能.