Semisupervised dimensionality reduction for hyperspectral images based on the combination of semisupervised learning and metric learning

This paper presents a semisupervised dimensionality reduction (DR) method based on the combination of semisupervised learning (SSL) and metric learning (ML) (CSSLML-DR) in order to overcome some existing limitations in HSIs analysis. Specifically, CSSML focuses on the difficulties of high dimensionality of hyperspectral images (HSIs) data, the insufficient number of labelled samples and inappropriate distance metric. CSSLML aims to learn a local metrics under which the similar samples are pushed as close as possible, and simultaneously, the different samples are pulled away as far as possible. CSSLML constructs two local-reweighted dynamic graphs in an iterative two-steps approach: L-step and V-step. In L-step, the local between-class and within-class graphs are updated. In V-step, the transformation matrix and the reduced space are updated. The algorithm is repeated until a stopping criterion is satisfied. Experimental results on two well-known hyperspectral image data sets demonstrate the superiority of CSSLML algorithm compared to some traditional DR methods.     

漆酶介体体系对纸模材料强度与疏水性的影响

目的利用漆酶介体体系对杨木CTMP浆进行生物酶处理,研究优化后的漆酶介体体系对纸浆模塑包装材料强度和表面疏水性能的影响。方法利用正交试验方法和红外光谱以及扫描电镜等手段,分析拉伸强度、接触角、纤维表面木素结构、纤维表面形貌等的变化。结果漆酶介体体系处理杨木浆的最优方案为A2B1C4D3E2,最优反应条件为漆酶用量1.68 g,介体0.2%(均相对绝干浆),pH值为6,反应温度为60℃,反应时间为90 min,通空气。结论在此条件下采用漆酶介体体系处理杨木CTMP浆,纸浆中残余木素在漆酶处理过程中部分会被氧化降解,使纤维间粘结作用得到增强,纸浆模塑包装材料的强度与疏水性得到提高。     

废纸浆增强玉米淀粉基复合材料的制备及其力学性能研究

以甘油和尿素作为混合塑化剂、废纸浆为增强体,玉米淀粉、聚乙烯醇为基体,利用熔融共混法制备了废纸浆增强玉米淀粉复合材料。研究了混合增塑剂、废纸浆、水含量、氢氧化钠浓度对复合材料力学性能的影响。力学性能测试结果表明,甘油和尿素混合塑化剂对复合材料有反增塑作用,当甘油/尿素含量分别为10/20份时,拉伸强度最佳为10.26MPa;氢氧化钠浓度为4%时,复合材料综合力学性能最好;废纸浆对复合材料有增强作用,当含量为35份时,拉伸强度最佳为11.35MPa;随着含水率的增加,材料的拉伸强度降低,断裂伸长率先增加后降低;扫描电镜观察发现,甘油和尿素混合塑化剂能够增塑淀粉,很好的改善废纸浆和玉米淀粉之间的相容性。     

生物体中重金属元素分析方法的研究进展

重金属污染威胁人类健康和物种生存,已成为全社会关注的环境热点,因此,重金属防治和检测显得尤为重要。在分析重金属元素检测现状的基础上,该文对生物体内重金属的主要检测及样品前处理方法进行了综述,讨论了当前生物体中重金属检测的新技术,提出了所存在的问题并展望了这一方面的发展趋势,以期为发展出更灵敏、更准确、更快速的检测方法提供参考。     

纸浆发泡缓冲材料研究

以纸浆为原料,使用复合发泡剂(碳酸氢钠、钾明矾、淀粉、酒石酸氢钾、轻质碳酸钙),制作纸浆发泡缓冲材料,得到稳定的实验配方,所得发泡材料的静态缓冲系数在4～5之间.     

相似度距离耦合角度径向变换的图像配准算法

目的为了解决当前图像配准算法因利用l1距离或l2距离相似度测量手段来完成图像特征点匹配,使其忽略了相位信息,难以有效消除高斯噪声的影响,使其配准精度与效率不佳不足的问题。方法提出最优相似度距离耦合角度径向变换的抗噪图像配准算法。首先引入角度径向变换,以降低算法复杂度,快速提取图像的特征点。然后联合图像的幅度和相位信息,基于欧式距离测度,定义最优相似度距离测量模型,通过求解其全局最小值,对特征点完成匹配,提高算法的抗噪性能。最后将图像分割为内点与外点,择取6个内点,通过计算其变换矩的几何配准误差,改进随机样本一致策略,对匹配进行提纯,消除误配。结果仿真实验结果显示,与当前基于l1距离或l2距离相似度测量的图像配准技术相比,该算法具有更强的抗高斯噪声性能和更高的匹配精度,且算法时耗最短。结论所提算法能够精确完成图像特征配准。     

纸浆模制波状结构缓冲性能的仿真影响因素

目的对纸浆模制双向波状结构的静态压缩缓冲性能进行有限元仿真模拟,分析影响仿真结果的各种因素。方法设计纸浆模制双向波状结构,制备样品并测试其缓冲性能;建立有限元模型并进行模型可靠性的验证,在此基础上分别讨论网格数目、摩擦因数、材料模型、弹性模量和泊松比的变化对仿真结果的影响。结果网格数目的划分、泊松比、材料模型和弹性模量的变化对纸浆模制双向波状结构的仿真结果影响较大,摩擦因数的变化对仿真结果影响较小。结论在进行有限元分析前应对模型进行网格无关性验证;材料模型应选取各向同性;静态压缩时载荷值会随着弹性模量和泊松比的增大而增大,呈现非线性增长模式。     

基于TRIZ理论的成垛浆粕上料机设计

目的针对目前成垛浆粕上料采用人工操作产生的劳动强度大、效率低、人力成本高的问题,设计一种成垛浆粕自动上料机。方法运用TRIZ理论的冲突解决原理进行成垛浆粕自动上料机设计,设计中对存在的问题进行归纳和分析,根据自动上料机的冲突矩阵,得到相应的创新设计原理,通过分析比较选择最佳原理解决设计中涉及到的技术冲突问题,并利用有限元软件对滑套进行力学分析。结果基于TRIZ理论设计的自动上料机可实现自动寻料、自动夹紧、自动提升、自动旋转、自动放料。结论该上料机完全取代了人工操作,生产效率提高了38%。     

Transportation,handling, and microbial growth performance of molded fiber and expanded polystyrene apple trays

Washington State apples are shipped all over the United States for retail sales. Adequate packaging is needed to minimize apple damage during distribution. Two common materials used for apple trays are expanded polystyrene (EPS) and molded fiber (MF). A recent industry change from MF to EPS trays provoked an interest in exploring the performance difference between the two. Distribution environment hazards include shock, vibration, and compression forces. Prior work has focused only on comparing vibration or shock performance of EPS and MF trays used in protecting apples. In this study, a variety of typical hazards encountered between case pack and retail preparation are considered on a larger sampling scale. The shock, vibration, and interlayer dynamic compressive forces are simulated as well as free‐fall drops possible with manual handling of the cases. A novel device and test method is developed to simulate the forces because of human hands removing trays of apples from the case at retail. Further, a microbial analysis of worst case apple condensation is performed to compare the tray materials effect on apple microbial populations. It is concluded through physical and microbial testing that there is no statistical difference in the physical protection or the growth of microbial populations between EPS and MF apple trays. Most significant tray damage is observed in the EPS trays because of free‐fall drop testing. Apple tray material selection can be shifted to other factors such as cost or consumer preference.     

Robustness of asymptotic accelerated life test plans to small‐sample settings

Much of the statistical literature on optimal test planning for accelerated life testing utilize asymptotic methods to derive optimal test plans. While sufficient effort is made to assess the robustness of these test plans to the choice of design parameters and distribution assumptions, there is very little literature on the performance of asymptotic test plans relative to small samples (on the order of 10‐15 samples). An alternative concern is that the asymptotic test plans may not necessarily be the true “optimal” test plan for a given sample size. The purpose of this research is to present exact or “near‐exact” methods for developing test plans and compare the performance of these test plans with corresponding asymptotic test plans in small‐sample settings. The optimal location of design points and sample allocation is determined using each method for lognormal and Weibull lifetime distributions with both complete and Type 1 right‐censored data under two selected acceleration factor models. The investigations reveal that asymptotic test plans tend to corroborate quite well with exact test plans and thus are suitably robust to small‐sample settings in terms of optimal variance.