μCLinux在TMS320DM270评估板上的移植

给出了以DSP＋ARM结构的嵌入式处理器为目标移植μCLinux操作系统的过程,其目的在于使得评估板成为一个灵活的适用于开发各种便携式影像和多媒体产品的开发平台.     

福建省耕地等别空间分布特征研究

以福建省区域内耕地质量分等成果为基础,利用面积加权和空间分析两种方法,综合分析了全省耕地等别的空间分布特征.研究结果表明,福建省内无劣等地分布,耕地平均等高于全国平均等;全省耕地等别空间分布存在差异性.结合福建省耕地保护网络化监管试点项目耕地保护评价结果发现,分布在中区和差区的耕地面积占全省总耕地面积的50%以上,且中、差区的优等地面积占全省优等地面积的75%.福建省耕地等别总体偏高,耕地等别的空间分异性受到自然条件和经济条件的影响,全省耕地等别存在下降的风险.     

第三方物流服务质量约束下具有利他性的网购供应链决策模型*

针对单个网络商店和单个第三方物流(TPL)形成的服务供需关系,在TPL服务质量约束下构建了一个基于利他属性的网购供应链决策模型,讨论了利他属性对网购供应链系统的影响。首先在分散决策模式下,探讨了系统的均衡解和绩效;然后,分析了集中决策模式下参与者的决策和利益情况,对比分析发现分散决策模式下网络商店和TPL会因利益冲突而使系统决策失衡,从而降低了供应链参与者利润和系统绩效;在此基础上,讨论了在TPL服务质量约束下利他性与系统决策和绩效的关系,结论表明:利他属性的存在有助于改善系统决策和供应链绩效;最后,通过数值分析,进一步揭示了单方参与者具有利他性时的系统决策和绩效的变化规律,以及双方参与者切利他性互动情景下系统决策的变化规律。     

多分量地震监测系统AETA的研究与实现

研制多分量地震监测系统AETA(acoustic & electro-magnetic testing all in one system)。在云南、四川、西藏、河北、北京、广东等地区的现场实验表明, 该系统能够满足大区域密集布设中高灵敏度、低成本和易布设的需求。同时, 若干点的实验观测数据和均值、振铃率、峰值频率在一定程度上反映了映震效果。目前正在中国西南部、首都圈、台湾海峡等地区密集布设, 系统地开展映震效果研究。     

Preparation and performance of a cold gas dynamic sprayed high-aluminum bronze coating

By mixing preheated high-aluminum bronze powders with different amounts of Al₂O₃ powder, a low-pressure cold-sprayed coating was prepared and sprayed onto a Cr12MoV steel substrate. The hardness of the coating and the bonding strength between the coating and the substrate were tested with a HV-1000 microhardness tester and a mechanical universal testing machine. The surface microstructure, cross-section and tensile fracture surface of the coating were observed with a scanning electron microscope (SEM). Correspondingly, the influences of the preheat treatment temperature of the bronze powder and the Al₂O₃ content on the coating performance were investigated. The results indicate that the hardness of bronze powders decreased and the coating deposition rate increased after the preheating treatment of the bronze powder. The Al₂O₃ content in the mixed powders contributed to the deformation of bronze powders during the spraying process. This trend resulted in varied performance of the coating.     

Effect of Ce addition on microstructures and mechanical properties of A380 aluminum alloy prepared by squeeze-casting

The effect of cerium (Ce) addition on the eutectic Si, β-Al₅FeSi phase, and the tensile properties of A380 alloy specimens prepared by squeeze-casting were studied by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The experimental results showed that Ce more effectively modified the eutectic Si and refined the β-Al₅FeSi. The refinement effect significantly increased under a specific pressure of 100 MPa with the addition of Ce from 0.1wt% to 0.9wt%. In contrast, the average length and the aspect ratio of the eutectic Si and β-Al₅FeSi exhibited their optimal values when the content of the added Ce was greater than 0.5wt%. Needle-like Al8Cu4Ce was precipitated with the addition of excessive Ce; hence, the mechanical properties of A380 gradually decreased with increasing Ce content in the range from 0.3wt% to 0.9wt%.     

高速大功率车用永磁同步电机电磁诱发转子横向振动特性

高速大功率车用永磁同步电机的转子轴系是一个涉及电磁、机械高度耦合的非线性系统,因此转子动力学性能是高速车用永磁同步电机设计必须关注的问题.建立了电机中由于转子偏心引起的电磁激励解析模型,以转子动力学和非线性动力学为基础,建立永磁电动机转子系统的非线性模型,用解析法计算得到转子横向振动的幅频特性,结果表明转子横向振动具有负刚度和失稳幅值跳跃现象.最后通过数值计算对等效解析计算的结果进行了验证.     

Damage evolution and failure mechanism of thermal barrier coatings under Vickers indentation by using acoustic emission technique

Acoustic emission(AE) technique was adopted to monitor the damage evolution of air plasma-sprayed(APS) yttria-partially-stabilized zirconia(YSZ) thermal barrier coatings(TBCs) during instrumented indentation testing, and then the failure mechanisms were investigated by cluster analysis and wavelet transform methods.The results of cluster analysis showed that there were three classes associated with distinct failure types for the 8YSZ coatings under Vickers indentation. Based on wavelet transform, these three clusters could be clearly distinguished from their dominant frequency bands, which were concentrated on levels A5(0–156.25 kHz), D5(156.25–312.5 kHz) and D4(312.5–625 kHz), respectively. Thus, the failure mechanism of 8YSZ coatings under Vickers indentation could be clarified by the distribution of different failure types in indentation depth. To sum up, as indentation load increases, the 8YSZ coatings can accommodate the indenter by elastic or little plastic deformation, microcracks propagation and then debonding at the splat boundaries. By comparing the distribution of AE signals induced by different failure types in indentation depth for samples with different thermal exposure time, it can be inferred that thermal exposure treatment can accelerate the degradation of APS 8YSZ TBCs.     

二氧化硅微球的可控制备研究

通过St9ber法制备二氧化硅微球.研究了水醇比例、无机盐种类含量等对二氧化硅微球的微观形貌和粒径分布影响.结果表明,随着反应溶液中去离子水量的增加,二氧化硅微球的粒径逐渐变小.此外,无机盐的添加也会在一定程度上促进二氧化硅微球的长大.究其原因,是因为电解质的加入会破坏微球表面双电层的稳定性,进而促使其发生团聚形成粒径更大的颗粒.     

超密齿面铣刀的铣削力波动特性及其影响

提出了一种超密齿面铣刀概念,并推导了x和y方向的铣削力计算模型,分析了超密齿刀具铣削力及其波动规律.结果显示:随刀具的转动铣削力呈锯齿状变化,x向铣削力波动呈现两个山峰状,在三齿同时参与切削时波动最小.y向铣削力波动随初始切入角的增大先增大后减小,对比发现超密齿刀具铣削力波动远小于疏齿刀具.提出用单位体积材料所需切向铣削力大小来评价超密齿刀具和疏齿刀具性能.通过超密齿面铣刀的铣削实验验证了铣削力计算模型,并发现铣削力波动是影响工件表面粗糙度的因素之一,同时也反映出超密齿刀具的加工优越性.