The Periodic Boundary Problem and the Initial Value Problem for a Nonlinear System of Equations of Changing Type

In this paper, we study the global existences of regular solutions, classical solutions and C^∞-solutions of the periodic boundary problem and the initial value problem for a nonlinear system of equations of changing type.     

On the Second-order Equations of Mixed Type of First Kind

In this paper the generalized Tricomi problem for the second-order equation of mixed type of first kind is considered. The uniqueness or solutions is proved under very weak conditions oil the coefficients or equation and the boundary curve of domain. The existence of H¹ strong solutions is proved for the Tricomi problem.     

The Global Solutions of a Nonlinear System of Equations of Changing Type

In this paper, the global existence of regular solutions to the initial-boundary value problem for a higher-order multidimensional system of equations of changing type with a strong nonlinear term is studied.     

RDF热解前后表面结构变化的研究

对城市生活垃圾衍生燃料(RDF)及其在不同温度及时间下快速热解生成半焦的比表面积和孔容积的变化进行了分析研究。实验结果发现RDF热解时比表面积及孔容积先随热解温度升高而降低,然后随反应程度的加深而增大,在约550℃时出现极大值,而后由于产生结焦等原因再次降低。研究表明RDF热解半焦孔结构与煤焦孔结构变化有一定的相似性。此外对RDF及半焦孔结构分布的分形特征进行了初步分析。     

Ni-W-Co/SiC复合材料磨损特性与磨损机制

研究了ＳｉＣ颗粒和ＳｉＣ晶须为复合第二相的Ｎｉ－Ｗ－Ｃｏ合金基复合材料的磨损特性和磨损机制．结果表明,复合相含量、几何特性及载荷和滑动速度对复合材料的耐磨性影响很大．其原因在于ＳｉＣ颗粒与ＳｉＣ晶须以不同的形式发生流失．     

基于混沌自适应粒子群人工神经网络的气体在聚合物中的溶解模型

为提高溶解预测模型的效率和关联度, 建立基于混沌理论、自适应粒子群优化(PSO)算法和反向传播(BP)算法的混沌自适应PSO-BP神经网络模型, 并对二氧化碳(CO₂)在聚苯乙烯(PS)和聚丙烯(PP)中、氮气(N₂)在PS中的溶解度进行预测试验. 模型选用压力和温度作为输入参数, 使用试探法确定隐含层结点个数为8, 输出为预测的溶解度. 模型融合混沌理论、自适应PSO和BP算法各自的优势, 提高了训练速度和预测精度. 结果表明, 混沌自适应PSO-BP神经网络有很好的预测能力, 预测值与实验值相当吻合, 通过与传统BP神经网络和PSO-BP神经网络的比较可知, 其预测精度和相关性均明显较优, 预测平均绝对误差(AAD), 标准偏差(SD)和平方相关系数(R²)分别为0.0058, 0.0198和0.9914.     

Robust self-healing waterborne polyurethane coatings via dynamic covalent Diels-Alder bonds for corrosion protection

For waterborne polyurethanes (PUs), balancing robust mechanical performances and excellent self-healing ability is a great challenge. Here, we show that this goal can be achieved by a rational tuning of the PU chemistry. In particular, we synthesized an anionic self-healing waterborne PU using acetone process, in which 2,2-bis(hydroxymethyl)propionic acid (DMPA) serves as inner emulsifier, thermally dynamic Diels-Alder bonds act as healing motifs and hexamethylene diisocyanate trimer is the crosslinker. The mechanical performance can be tuned by increasing DMPA concentration due to the gradually increased hard segment contents and ionic interactions. The tensile stress and elongation at break of films containing 5.6 wt% of DMPA are 24.9 MPa and 911.9%, respectively. Moreover, dynamic reversible Diels-Alder bonds located in main chains and cross-linking points ensure excellent self-repairing capability. Upon mechanical damage, the tensile stress can be restored to 95% of its initial value. Electrochemical impedance spectroscopy also points out an outstanding barrier ability and excellent corrosion protection performance of the coatings, which can be recovered even after serious damages.     

去卤缩聚法合成蓝色电致发光聚合物聚（2,5—二庚基）对苯乙炔

利用双卤甲基苯衍生物在强碱诱导下的缩合反应，合成了共轭态可溶的聚对苯乙炔，并利用ＩＲ，ＵＶ－Ｖｉｓ，＾１Ｈ－ＮＭＲ，ＴＧＡ等对聚合物结构与性能进行了有征，其Ｎｎ＝０．４８×１０＾４。电致发光器件的发光峰值波长为４８６ｎｍ，起亮电压为２２Ｖ。     

On the spherically symmetric gauge fields

The spherically symmetric gauge fields with a compact gauge group over 4-dimensional Minkowski space are determined completely. Expressions for the gauge potentials of these fields are obtained.     

通过τ→a_1v→π~±π~0π~0v道测量由Z~0衰变的τ的极化不对称性

利用L3合作组1992年和1993年的数据，通过τ→a1v→π±π0π0v道测量了由Z0衰变的τ的极化不对称性A(pol)＝－0．239±0．126±0．100，其中第一项误差为统计误差，第二项误差为系统误差．由此推断有效电弱混合角sin2θw＝0．2197±0．0219．