科创中国

Forming limit curves(FLCs) are commonly used for evaluating the formability of sheet metals. However, it is difficult to obtain the FLCs with desirable accuracy by experiments due to that the friction effects are non-negligible under warm/hot stamping conditions. To investigate the experimental errors, experiments for obtaining the FLCs of the AA5754 are conducted at 250℃. Then, FE models are created and validated on the basis of experimental results. A number of FE simulations are carried out for FLC test-pieces and punches with different geometry configurations and varying friction coefficients between the test-piece and the punch. The errors for all the test conditions are predicted and analyzed. Particular attention of error analysis is paid to two special cases, namely, the biaxial FLC test and the uniaxial FLC test. The failure location and the variation of the error with respect to the friction coefficient are studied as well. The results obtained from the FLC tests and the above analyses show that, for the biaxial tension state, the friction coefficient should be controlled within 0.15 to avoid significant shifting of the necking location away from the center of the punch; for the uniaxial tension state, the friction coefficient should be controlled within 0.1 to guarantee the validity of the data collected from FLC tests. The conclusions summarized are beneficial for obtaining accurate FLCs under warm/hot stamping conditions.

针对物流信息平台中信息资源采集系统建设的不足,提出建立基于Nutch的网页资源定向采集系统,并对中文分词、主题相关度分析、结果排序、正文解析等关键模块进行重点探讨.最后在一定条件下进行了实验,并分析了实验结果.

目的 通过了解巨噬细胞游走抑制因子(MIF)和环加氧酶(COX-2)、神经生长因子(NGF)在化学性前列腺炎大鼠模型前列腺、膀胱、尿道中的表达及这些器官的炎症情况,以探讨前列腺炎是否引起临近盆腔脏器炎症,以及引起前列腺炎临床症状的机制.方法 (1)实验动物分组:20只健康成年雄性SD大鼠随机分成两组,即福尔马林(formalin)组和生理盐水(saline)组,每组10只.(2)采用腹侧前列腺内注射福尔马林法建立化学性前列腺炎模型.(3)用HE染色法检测前列腺、膀胱、尿道的炎症情况.(4)用免疫组织化学方法、Western blot法检测各标本MIF、NGF和COX-2的表达.结果 观察到前列腺注射福尔马林引起了前列腺、膀胱和尿道炎症的组织学改变.包括前列腺注射福尔马林后膀胱和尿道MIF蛋白量降低,而COX-2蛋白和NGF蛋白量增加.结论 大鼠化学性前列腺炎通过神经反射引起膀胱、尿道上皮细胞释放P物质,促使MIF释放,诱导其他炎性介质如COX-2,NGF的活化,进而引起临近脏器如膀胱、尿道出现炎症,并维持炎症循环,出现临床症状.