车用汽油辛烷值浅论

本文简要地介绍了汽油辛烷值的基本概念以及辛烷值测量的意义。     

学生公寓:高校育人的重要场所

学生公寓是大学生在校四年中学习、生活的最主要场所之一,在大学生身心的发育、能力的锻炼、素质的提高、品行的修炼与养成等方面扮演着重要角色.要进一步增强高校整体育人工作的实效性,必须采取得力措施,充分发挥学生公寓管理育人、服务育人、环境育人的功能.     

悬臂式管桩在基坑支护工程中的应用研究

基于土拱效应及土体M-C屈服准则,建立了桩间土拱计算模型,并得到了悬臂段桩身土反力计算公式;考虑桩身挤土效应及深度效应,利用Vesic圆孔扩张理论,推导出挤土管桩水平承载力与水平位移之间的关系式;在此基础上,利用力和弯矩平衡条件,建立了悬臂式管桩支护结构设计方法.为了验证理论公式的可行性,将计算结果、现场实测结果及朗肯土压力计算结果进行对比分析,结果表明本文计算结果与实测结果桩侧土反力相差较小,且变化趋势基本一致,并且其计算精度相对经典土压力理论得到较大的提高,验证了理论方法的可行性.     

二阶随机占优约束保险资金资产组合优化

建立二阶随机占优约束的保险资金资产组合优化模型,论述模型的罚问题,并在保险资金的收益率和基准收益率都为离散有限分布的情况下,用光滑化方法来处理模型,从而简化了模型的求解.为保险公司的资产组合及最优投资比例提供了一种可借鉴的思路.     

Angular response of ‘pin-hole’ imaging structure measured by collimated β source

The pitch-angle distribution of energetic particles is important for space physics studies on magnetic storm and particle acceleration.A‘pin-hole’imaging structure is built with the‘pin-hole’technique and a position sensitive detector,which can be used to measure the pitch angle distribution of energetic particles.To calibrate the angular response of the‘pin-hole’imaging structure,special experiment facilities are needed,such as the particle accelerator with special design.The features of this kind of particle accelerator are:1)The energy range of the outgoing particles should be mid-energy particles(tens keV to several hundred keV);2)the particle flux should be consistent in time-scale;3)the directions of the outgoing particles should be the same and 4)the particle number within the spot should be low enough.In this paper,a method to calibrate the angular response of the‘pin-hole’imaging structure by the90Sr/90Y β source with a collimator is introduced and simulated by Geant4 software.The result of the calibration with the collimated β source is in accord with the Geant4 simulations,which verifies the validity of this method.     

城市居住区室外热环境的分析方法

针对建筑室外热环境模拟研究中对物理模型过于简化的问题,提出了一种基于数字图像分析的室外热环境模拟方法,实现了图像处理技术与数学模型的结合,有效地分析了室外热环境分布情况,并在测试结果和模拟结果的对比分析中得到证实,研究结果为室外热环境的研究方法提供了新的参考。     

Preliminary study on some properties of Co-Cr dental alloy formed by selective laser melting technique

The surface condition, some properties and ion releasing behavior of cobalt-chromium (Co-Cr) dental alloy formed by selective laser melting (SLM) technique were investigated. Before porcelain fused firing, the surface condition of the Co-Cr alloy was observed using a scanning electron microscope (SEM), and then the density and hardness were examined. After porcelain fused firing, the interface of porcelain and alloy was observed, and then the metal-ion release of the samples was tested. SLM technique provides Co-Cr alloy higher hardness than casting method. After degassing-oxidation procedure and porcelain fused firing, the interface of the alloy and porcelain showed excellent combination. Co ion was more than Cr ion released from SLM Co-Cr alloy, the amounts of Co and Cr ions were safe according to ISO security criterion. Considering the properties before and after porcelain fused sintering process, SLM technique is suitable for dental Co-Cr alloy restoration.     

三电平逆变器供电永磁同步电机直接转矩控制研究

针对临近空间飞行器电驱动系统的高效控制问题,构建一种三电平逆变器供电永磁同步电机直接转矩控制系统,以减少输出电流的谐波含量,降低转矩脉动,提升驱动系统整体效率。针对三电平逆变器空间电压矢量调制(SVPWM)实现复杂的问题,通过对大、小电压矢量选择的归纳研究,利用矢量的对称性和归一化处理方法,提出一种易于通过可编程器件实现的简洁计算方法,实现不同扇区的统一计算;构建参考矢量的复数表达形式,利用极坐标相角信息简化扇角区间判别。采用Matlab/Simulink分别构建传统两电平逆变器和三电平逆变器直接转矩控制系统进行对比分析,仿真结果验证了该算法在减小电流谐波和削弱转矩脉动方面的有效性。     

塔中岩溶储层地震反射地质特征及其成因机理

综合地震反射强弱及反射形态的差异,将地震反射类型划分为串珠状反射、片状反射、杂乱反射和弱反射,并对串珠状反射和片状反射进行细分.总结塔中西部下奥陶统鹰山组地震反射特征与岩溶储层对应关系,在此基础上比较每种地震反射类型所对应地质特征的差异,归纳形成四种地震反射类型的地质原因.     

基于 KQML的多智能体系统建模与验证

为了保证 MAS相关属性的可满足性、有效性以及验证的高效性,提出了一种基于 KQML 通信语言的MAS建模以及能够实现自动验证相关规范的方法.设计并实现了 KQML 语言转化为完整描述状态转换关系的一组状态迁移七元组的算法,以及从七元组到多智能体模型检测工具 MCMAS输入语言ISPL的转化算法,从而实现多智能体系统的自动形式化建模,并用 MCMAS对多智能体系统规范的正确性进行验证.实验结果表明,所提出的算法不仅能够验证多智能体系统的时态规范,还能验证其特有的认知规范.