基于绿色再制造的多层激光送丝堆焊

作为再制造工程的关键技术之一的激光送丝堆焊技术,在重要零件的修复中起到独特的作用,本文通过在45号钢上用大功率CO2 激光束和自动送丝机构进行激光堆焊工艺试验研究,就这一技术的特点、工艺控制方法以及组织性能等方面做了考察,结果显示:优化的工艺范围为比能量Es=100-130J/mm2、送丝速度应高于激光扫描速度(ΔV=1.5~2.5 mm/s);与氩弧堆焊相比激光堆焊层组织明显细化,硬度提高70%,过渡区狭小,激光堆焊层显维组织随Es增加而逐渐粗大,同时,热影响区易出现过热组织;激光堆焊层体现出良好的抗磨性能,比高速钢的耐磨性提高42.6%。     

Carbon Fiber Reinforced Thermoset Composite with Near 100% Recyclability

Both environmental and economic factors have driven the development of recycling routes for the increasing amount of composite waste generated. This paper presents a new paradigm to fully recycle epoxy‐based carbon fiber reinforced polymer (CFRP) composites. After immersing the composite in ethylene glycol (EG) and increasing the temperature, the epoxy matrix can be dissolved as the EG molecules participate in bond exchange reactions (BERs) within the covalent adaptable network (CAN), effectively breaking the long polymer chains into small segments. The clean carbon fibers can be then reclaimed with the same dimensions and mechanical properties as those of fresh ones. Both the dissolution rate and the minimum amount of EG required to fully dissolve the CAN are experimentally determined. Further heating the dissolved solution leads to repolymerization of the epoxy matrix, so a new generation of composite can be fabricated by using the recycled fiber and epoxy; in this way a closed‐loop near 100% recycling paradigm is realized. In addition, epoxy composites with surface damage are shown to be fully repaired. Both the recycled and the repaired composites exhibit the same level of mechanical properties as fresh materials.     

深亚微米IC物理设计流程中的串扰控制

信号完整性的设计收敛已经成为当前深亚微米集成电路物理设计流程中的关键问题。对信号完整性收敛产生不利影响的有三个因素：串扰、直流电压降和电迁移。其中影响最大的是串扰,串扰噪声会产生大量的时序违规、逻辑错误。主要关注基于串扰控制的物理设计方法,包括新的流程、各个设计阶段对串扰的分析及修正的方法,以达到快速的时序收敛。并且根据真实的设计实例,提出了几点有效的控制串扰的方法和对于信号完整性管理比较有价值的观点。     

有线数字电视用户端故障维修若干实例

随着广电网络不断升级和改造,电视网络已从模拟信号步入数字信号的新阶段,数字信号的推广和实施使用户能够看到更加清晰的电视节目和享受更多的服务,但是与此同时有线数字电视用户端的故障也在所难免,通过有线数字电视用户端故障维修的若干实例,简要介绍了排除故障的基本方法。     

DYL高速视频12位DAC的研制

文中介绍了以我国独创的DYL多元逻辑电路为基础,并配合了申请国家发明专利的高速差动电压模拟开关构成的12位高速DAC转换器。同时解决了以往高速转换器输出阻抗、使用范围受限的缺点。同时对所研制的高速DAC在结构、工艺、修正技术及测试上进行了多方面的研究探讨。     

Bioinspired Highly Anisotropic,Ultrastrong and Stiff,and Osteoconductive Mineralized Wood Hydrogel Composites for Bone Repair

Anisotropic hydrogels mimicking the biological tissues with directional functions play essential roles in damage-tolerance, cell guidance and mass transport. However, conventional synthetic hydrogels often have an isotropic network structure, insufficient mechanical properties and lack of osteoconductivity, which greatly limit their applications for bone repair. Herein, inspired by natural bone and wood, a biomimetic strategy is presented to fabricate highly anisotropic, ultrastrong and stiff, and osteoconductive hydrogel composites via impregnation of biocompatible hydrogels into the delignified wood followed by in situ mineralization of hydroxyapatite (HAp) nanocrystals. The well-aligned cellulose nanofibrils endow the composites with highly anisotropic structural and mechanical properties. The strong intermolecular bonds of the aligned cellulose fibrils and hydrogel/wood interaction, and the reinforcing nanofillers of HAp enable the composites remarkable tensile strength of 67.8 MPa and elastic modulus of 670 MPa, three orders of magnitude higher than those of conventional alginate hydrogels. More importantly, the biocompatible hydrogel together with aligned HAp nanocrystals could effectively promote osteogenic differentiation in vitro and induce bone formation in vivo. The bone ingrowth into the hydrogel composite scaffold also yields good osteointegration. This study provides a low-cost, eco-friendly, feasible, and scalable approach for fabricating anisotropic, strong, stiff, hydrophilic, and osteoconductive hydrogel composites for bone repair.     

自浮式气压沉柜在水下工程检修中的应用

万福闸管理所设计、研制的自浮式气压沉柜，适用于水深为2．8～7．5m的水下工程检修。它较其它常规水下检修方法具有投资少、移动灵活、排水方便、适应性强等优点。并已在葛洲坝、万福闸等8个大中型水下工程检修中成功应用，取得显著的社会和经济效益。     

Multifunctional Upconversion Nanoparticles for Dual‐Modal Imaging‐Guided Stem Cell Therapy under Remote Magnetic Control

Stem cells have generated a great deal of excitement in cell‐based therapies. Here, a unique class of multifunctional nanoparticles (MFNPs) with both upconversion luminescence (UCL) and superparamagnetic properties is used for stem cell research. It is discovered that after being labeled with MFNPs, mouse mesenchymal stem cells (mMSCs) are able to maintain their viability and differentiation ability. In vivo UCL imaging of MFNP‐labeled mMSCs transplanted into animals is carried out, achieving ultrahigh tracking sensitivity with a detection limit as low as ≈10 cells in a mouse. Using both UCL optical and magnetic resonance (MR) imaging approaches, MFNP‐labeled mMSCs are tracked after being intraperitoneally injected into wound‐bearing mice under a magnetic field. The translocation of mMSCs from the injection site to the wound nearby the magnet is observed and, intriguingly, a remarkably improved tissue repair effect is observed as the result of magnetically induced accumulation of stem cells in the wound site. The results demonstrate the use MFNPs as novel multifunctional probes for labeling, in vivo tracking, and manipulation of stem cells, which is promising for imaging guided cell therapies and tissue engineering.     

532nm激光照射后的兔视网膜损伤修复

目的:观察532nm激光照射后的兔视网膜损伤和修复。方法:采用(光斑直径约为2mm、照射时间100s、能量密度200J/cm2、532nm)激光照射家兔视网膜后极部,连续观察1d、3d、7d、14d和28d后眼底及组织学改变。结果:照后1d可见明显水肿及出血。3d后凝固斑边界清晰,出血范围扩大,可见脉络膜成纤维细胞开始增生。14d后渗出和出血大部分吸收。28d后大量纤维组织增生及新生血管形成。结论:该照射剂量可以引起家兔视网膜较为严重的损伤,其修复存在一定的规律性。     

市县级有线电视用户管理系统设计

通过构建局域网,利用计算机处理信息的准确、快速与强大的信息存储能力,设计出适合县市、乡镇有线电视台的用户管理系统软件,以提高有线电视用户管理水平,为有线电视的快速发展提供有力支持.