不同破口大小对B型主动脉夹层假腔内压力的影响

为了研究夹层内的血流动力学变化对夹层转归的重要影响,并期望为临床判断主动脉夹层发展及转归提供理论依据,通过3D打印技术制作不同出入口比例及破口大小的B型主动脉夹层模型,对主动脉夹层内血流变化进行模拟,并测量观察主动脉夹层模型假腔内压力变化及流场情况.真腔内固定压力为18.620、21.280 k Pa两组中,不同破口比例的假腔入口压力比普遍均小于夹层模型内其他假腔位置,且压力值低于真腔压力;真腔内压力为23.940 k Pa组中,破口比例为2∶1的夹层模型内假腔压力比较其他破口比例模型的压力比明显升高;所有模型真腔固定水压为21.280、23.940 k Pa下均可观测到同真腔压力下,真腔流速更快,其内部压力低于假腔.同一模型中,假腔压力普遍低于真腔压力;相同压力下,原发破口大的模型假腔流速相对较低,而涡流明显;相同模型相同压力下,假腔流速低于真腔,假腔的涡流更为明显,复杂的涡流和旋动对壁面造成冲击进而使假腔破裂风险增加.     

Partition model into 3D-printable and no supporting parts

The printing object must fit into the printing working volume and overhangs require a disposable support structure to be added, which are two main problems in the 3D printing process. Existing algorithms cannot solve these two problems at the same time. To solve these problems, we present a model partition algorithm, dividing the model into the pyramidal fitting printing working volume, with the pyramidal having the shape which can be printed without a supporting structure. Firstly, we partition the model surface using the region growing method and analyze the region's normal vector to determine the candidate dividing directions. Secondly, we use the candidate dividing directions to generate candidate dividing planes in order to segment the model. If the divided sub-model is not a pyramidal,continue segmenting the sub-model by using the same method until all of the sub-models are pyramidal. The candidate dividing planes may generate multi-group division modes. Each division mode constructs a tree, the evaluation function is employed to appraise the dividing values and the beam search method is utilized to search the largest value tree in the solution space which is the optimal partition. Experimental results show that the proposed algorithm can divide the model into sub-models which needn't support structures and fit into the printing working volume.     

基于数字光处理技术的3D打印技术

介绍了以数字光处理(digital light processing,DLP)技术发展出的3D打印技术并讨论了其光学系统对成型效果的影响.介绍了现有3D打印技术的种类、光固化快速成型技术以及DLP技术的原理.说明了以DLP技术为核心的3D打印系统的基本结构,具体说明了DLP技术如何运用于快速成型领域.内容包括数字微镜器件(digital micro-mirror device,DMD)的组成和驱动原理、DLP技术中使用的典型光学系统结构,以及它们在3D打印技术中起到的作用.接着,讨论了在3D打印应用中,DLP技术需要注意的问题.内容包括DLP系统适用的光波长、投影幅面的均匀性和成型精度.最后,总结了DLP技术在3D打印领域的优势及不足.     

绘图仪式高速激光树脂3D打印设备研制

为了进一步探索3D打印实现方法,提高精度和效率,在绘图仪的结构基础上,结合光固化立体打印技术(SLA)的原理,设计了一种用于树脂材料的绘图仪式3D打印设备(SLP),它拥有绘图仪式的运动结构,激光及聚焦部分可直接做xy二维运动.相对于SLA技术,SLP大幅减小了焦距,所以对光源的要求更低.相比SLA和数字光处理技术(DLP),SLP加工幅面更容易扩大.     

两墨辊对滚过程中相邻墨区间的影响

对两墨辊的对滚转动进行了模拟仿真分析,旨在研究相邻墨区之间的相互作用,以及主动辊的串动对油墨流动特性的影响.为此,以相邻5个墨区进行仿真分析.对中间墨区墨量等于、小于和大于相邻墨区3种情况下墨辊的对滚转动模拟仿真,以对比分析相邻墨区对中间墨区的影响.分析得出,在两墨辊对滚转动的过程中,相邻墨区之间相互作用,使得墨辊上油墨流场的压力、轴向速度、墨层厚度都受到影响.对主动辊有轴向串动时,分析中间墨区的压力、轴向速度、墨层厚度可知,主动辊的串动增大了相邻墨区之间的相互影响.     

育果袋纸生产工艺改造及成本分析

与传统育果袋纸生产方法相比,采用印刷法生产育果袋纸具有生产效率高、环境友好等特点.在前期研究基础上,本文探讨了印刷法生产育果袋纸工艺设备的改造方案,可实现育果袋纸原纸生产与后续印刷过程连续化的目的.此外,还对以不同原料采用传统生产工艺——层合法制备育果套袋纸和以OCC为原料采用印刷法制备育果套袋纸的生产成本进行了比较.改造结果表明:无论采用圆网纸机或长网纸机,通过对设备进行简单地调整或增加印刷单元,即可实现印刷法育果套袋纸工艺的连续化生产;原料成本核算结果表明:以废旧瓦楞纸板纸浆为原料采用印刷法制备育果袋纸,其成本虽与传统方法相当,但却提高了生产效率,降低了环境污染.因此,若在今后的研究中,能够研究开发出适合育果袋纸生产的低成本油墨,对于育果袋纸产业而言具有较大的借鉴意义.     

复合絮凝剂与活性砂滤池协同深度处理印染废水研究及应用

采用复合絮凝剂和活性砂滤池协同处理印染废水,研究了复合絮凝剂对浊度、COD（化学需氧量）和TP（总磷）的去除性能,在实际运行系统中考察了复合絮凝剂和活性砂滤池协同处理后的出水水质情况.结果表明：活性砂滤池在平均处理水量为3500m3/h情况下,当复合絮凝剂投加量为ρ（PAC） =50 mg/L,ρ（FeCl3） =10.0 mg/L,ρ（APAM）=1.0 mg/L时,出水水质指标浊度、COD和TP的平均去除率分别达到了56.6％,45.3％,59.4％,出水水质各项指标均达到《城镇污水处理厂污染物排放标准》（GB 18918-2002）一级A标准.     

曝气生物滤池深度处理印染废水的实验研究

采用曝气生物滤池（BAF）对经生化预处理后的印染废水进行中试规模的深度处理实验研究,考察了水力负荷、进水有机负荷和滤层高度对污水化学需氧量（COD）和总磷（TP）的去除效果。结果表明：当BAF进水水力负荷为2.5 m3/（m2·h）,气水比为2∶1,进水COD和TP质量浓度分别为77.7~102 mg/L和0.872~0.957 mg/L范围变化时,COD和TP平均去除率分别达到了47.9%和46.0%,出水水质满足《城镇污水处理厂污染物排放标准》（GB 18918—2002）一级A标准。     

明代出版业的发展与通俗小说的勃兴

明代中后期,城市经济与文化持续发展,社会发生了一系列深刻的变革。商品经济空前繁荣,雕版印刷业迎来了发展高峰,刻印书籍数量之大、品种之多,刻印技术之先进是前代无法想象的。坊刻迎合市民意识高涨、市民文化日趋多元的社会需要,组织创作、编纂、刊刻了大量通俗小说,为通俗小说的发生流传提供了最直接、最重要的载体,促进了明代通俗小说的发展和繁荣。     

Mass transfer in 3D-printed electrolyzers: The importance of inlet effects

This article investigates the effect of inlet shape, entrance length, and turbulence promoters on mass transfer by using 3D-printed electrolyzers. Our results show that the inlet design can promote turbulence and lead to an earlier transition to turbulent flow. The Reynolds number at which the transition occurs can be predicted by the ratio of the cross-sectional area of the inlet to the cross-sectional area of the electrolyzer channel. A longer entrance length results in more laminar behavior and a later transition to turbulent flow. With an entrance length of 550 mm, the inlet design did no longer affect the mass transfer performance significantly. The addition of gyroid type turbulence promoters resulted in a factor of 2 to 4 increase in mass transfer depending on inlet design, entrance length, and the type of promoter. From one configuration to another, there was a minimal variation in pressure drop (<1600 Pa).