Preparation and Characterization of the Covalent-Integrated Poly（lactic acid） and Scrap Leather Fiber Composites

Scrap leather fibers (SLFs) modified with active silane containing epoxide groups were incorporated into poly(lactic acid) (PLA) modified by vinyl trimethoxysilane, i.e., the PLA/SLF composites were prepared for bio-composites by solvent compounding technology in this article. The effects of silane coupling agents on the structures of PLA and SLF molecules were examined, and the mechanical properties and thermal stability of PLA/SLF composites were also measured. The results of Fourier-transform infrared spectroscopy (FTIR) had proved that silane had been incorporated successfully to PLA and SLF molecules by means of the solvent technology. Scanning electric microscopy (SEM) was used to investigate both the changes in shapes between the pristine SLFs and the treated SLFs and the microscopic structures of composites. According to SEM results, it was shown that there were some significant differences between the untreated and treated SLFs, and a double continuous phase structure had occurred in PLA/SLF composites due to the excellent dispersion of SLFs in matrix. The addition of the treated SLFs into PLA resulted in a distinct improvement of the impact and tensile strengths. When the mass fraction of the treated SLFs was 15%, the notched impact strength and tensile strength of PLA/SLF bio-composites were improved by 34.4% and 21.2% compared with the pristine PLA, respectively. Additionally, with the increase of the modified SLFs content, the thermal stability of PLA/SLF bi-composites was apparently improved. The macroscopic properties of bio-composites were found to be strongly dependent on their components, concentration, dispersion and resulted morphological structures.     

威远互通立交E匝道现浇箱梁施工工艺及应用实例

介绍了威远互通立交E匝道现浇箱梁施工过程。阐述了现浇箱梁的施工工艺,该工艺不仅施工速度快,而且能保证箱梁的质量。     

基于改进Unet模型的混凝土裂缝分割研究

【目的】针对桥梁、隧道等环境下产生的混凝土裂缝情况复杂、干扰因素多的问题,提出一种改进Unet模型（A-Unet）的裂缝检测方法。【方法】以Unet网络为基础,研究了编码器的深度如何影响模型训练时间、检测精度。在解码过程中设计一种融合空间和通道注意力模块,将高分辨率的浅层特征与上采样获得的深层特征信息赋予不同权重,进一步增强裂缝特征。同时,增加dice损失函数对模型进行评价,减少因检测目标与背景数量相差较大,导致评价不准确的问题。【结果】在测试数据集中进行评价,精确度,MIou,召回率分别达到94.70%,86.16%,91.34%。A-Unet模型检测效果明显优于其他5种模型。【结论】利用该方法检测混凝土裂缝精度得到较大提升,且节约了模型训练时间,提高检测效率。     

浅谈蓄电池技术状态的检验

维修时,常会遇到车辆电起动失败故障,该类故障产生的原因比较复杂。电起动顺利起动发动机,首要的条件就是蓄电池要处于良好的技术状态,能够有力地驱动起动电机,拖动发动机达到起动转速,进入起动丁况。如果蓄电池技术状态不良,发动机无法起动着火。所以在排除故障时,要对蓄电池的技术状态进行检验,以便进一步分析排查故障疑点,快速排除故障。     

Petal failure characteristics of a conical projectile penetrating a thin plate at high oblique angle

In order to determine the impact depth of a conical projectile impacting a thin plate at high oblique angle, the residual velocity of the projectile after penetrating must be known. Based on the petal failure mode of the conical projectile impacting the thin plate at high oblique angle, the energy consumption mode of the target was determined. During the perforation process, the energy consumption of the target was completed by the saucerization, the power work of the petals, the propagation of radial cracks and petal bending. The energy formula was deduced for each energy dissipation mode and the energy consumed in the impact process was determined. The residual velocity and the ballistic limit velocity of the projectile were deduced by energy conservation principle. Comparison of the analytical results of the residual velocity to the numerical results demonstrates the accuracy and reliability of the analytical formula.     

墨西哥的城市交通

墨西哥位于北美洲南部,拉丁美洲西北端,是南、北美洲陆路交通的必经之地。北邻美国,南接危地马拉和伯利兹,东临墨西哥湾和加勒比海,西南濒太平洋。     

Cyclopamine联合YH-16对人胰腺癌BxPC-3细胞的抑制作用

目的 体外研究Hedgehog(HH)信号通路阻断剂Cyclopamine和抗血管生成剂YH-16对胰腺癌细胞株BxPC-3的抑制作用.方法 以Cyclopamine和YH-16单独或联合干预BxPC-3细胞,MTT法观察药物对肿瘤细胞生长的影响,流式细胞仪检测细胞凋亡,RT-PCR法检测细胞凋亡相关蛋白Bcl-2和Bax的表达情况.结果 Cyclopamine和YH-16对BxPC-3细胞均有明显的抑制作用,两者联合作用时抑制作用更强(P<0.05).Cyclopamine和YH-16均可诱导细胞凋亡,联合作用后细胞的凋亡率更高(P<0.05).Cyclopamine和YH-16均可下调Bcl-2和上调Bax的表达,联合用药则下调Bcl-2和上调Bax更明显(P<0.05).结论 Cyclopamine和YH-16能抑制BxPC-3肿瘤细胞的增殖,诱导细胞凋亡,两者联合作用时抑瘤效果明显增加,其机制可能与调控凋亡相关蛋白Bcl-2、Bax的表达有关.     

隧道明洞暗挖施工技术

介绍了景鹰高速公路北晨亭隧道明洞暗挖的施工技术。该隧道进入峡谷地段,根据线路设计有一地段隧道顶部露出原地面,经方案比选,采用先清理该地段表土,随后进行水泥稳定碎石分层回填压实,然后打设注浆管,实施注浆固结,形成壳体,最后在其保护下进行隧道暗挖施工成型。施工实践表明该施工方法合理、有效,对类似工程会提供有益借鉴。     

农村公路交通安全设施设置技术研究

农村公路的安全状况已不能满足人们对出行安全的期望。文章就农村公路的特点,结合我国国情阐述了在农村公路设置交通安全设施的方法:排查黑点、综合处理,诱导为主、防护为辅,因地制宜、旧材新用,经济有效、简单实用。针对保护弱势群体和超限严重路段提出具体诱导、减速、限行的对策。     

高塔横梁施工非落地支撑系统研究

高塔两塔肢间的横梁是大型的斜拉桥和悬索桥的结构构件之一,随着施工技术和工艺的进步,近年来高塔横梁施工中常用的支撑系统也在逐步改进。文章以一个具体工程为依托,利用MIDAS分析软件的建模和计算,深入的讨论了非落地支撑系统设计中鱼腹结构和张弦结构的位移和内力,为施工方案设计提供参考。