B超扫描仪支架五联动滑块机构模具设计

结合B超扫描仪支架塑件的形状特点，通过合理地选择塑件的分型面，简化了塑件的整体结构设计及脱模机构设计。针对塑件上脱模需要的复杂性，设计了一种五滑块联动机构先实施内壁5个倒扣及内壁凹形部位内壁的脱模；而后通过2个斜导柱滑块机构来实施外壁的脱模及侧端的侧孔抽芯脱模，塑件最后由推管顶出来实施最终的完全脱模。配合于脱模机构的动作需要，模架选用三板式模架，模架第一次打开设置用于驱动五滑块联动机构的抽芯动作，第二次打开设置用于驱动外壁及侧端的斜导柱驱动侧滑块机构的抽芯动作。五滑块联动机构设计中，通过一个中央T形槽驱动块，驱动中间过渡滑块，从而通过燕尾槽联结来带动5个成型滑块做内收式抽芯运动，巧妙地解决了塑件上局部区域内设置多个抽芯机构设计空间不够的问题，保证了塑件的自动化注塑生产的可靠实现。     

Assembly of a DNA Origami Chinese Knot by Only 15% of the Staple Strands

As a giant leap in DNA self-assembly, DNA origami has exhibited an unprecedented ability to construct nanostructures with arbitrary shapes and sizes. In typical DNA origami, hundreds of short DNA staple strands fold a long, single-stranded (ss) DNA scaffold cooperatively into designed nanostructures. However, large numbers of DNA strands are expensive and would hinder applications such as pharmaceutical investigations because of the complicated components. Therefore, one challenge is how to reduce the number of staple strands needed to construct DNA origami. For a DNA origami structure, the scale-free folding pattern of the scaffold strand is determined by staple strands at the branching vertexes. Simple duplex regions help to define the size-related features of the origami geometry. In this study, we hypothesized that a scaffold strand can be correctly folded into a designed topology by using only staple strands involved in branching vertexes. After assembly, any remaining, flexible, single-stranded regions of the scaffold could be converted into rigid duplexes by DNA polymerase to achieve the designed geometric structures. To demonstrate the concept, we used only 18 staple strands (covering 15 % of the scaffold strand) to assemble a porous DNA nanostructure, which was visualized by atomic force microscopy (AFM). This study helps understanding of the role of cooperativity in origami folding, and provides a cost-effective approach for small-scale prototyping DNA origami.     

Analysis on the spatial ecological distribution model of landscape plant community

Because the spatial pattern of plant communities in garden landscapes usually exhibits highly non-random distribution characteristics, the accuracy of the analysis results is not high. For this purpose, a spatial ecological distribution model of landscape landform plant communities is designed. Based on the remote sensing images of landscape plant communities, the study area was obtained. The grassland communities in this area were classified and calculated by geostatistics, and the semi variogram values of typical samples of different vegetation types were obtained. According to the calculation results, the spatial terrain factors of landscape plant community are extracted, and the annual NDVI value is taken as the ecological vitality index of landscape green vegetation, the NDVI level is divided, the spatial ecological distribution model of landscape plant community is constructed, and the evaluation index system is generated, so as to complete the spatial ecological distribution model analysis of landscape plant community. The results show that the method of this study accurately analyzes the area of coniferous and broad-leaved mixed forest, mountain meadow, road, construction land, water area land and slope grade, which is slightly different from the actual value, indicating that the method has certain reliability.     

Paradigm and performance analysis of distributed frequent itemset mining algorithms based on Mapreduce

FrequentItemsetMining (FIM) is one of the most important data mining tasks and is the foundation of many data mining tasks. In Big Data era, centralized FIM algorithms cannot meet the needs of FIM for big data in terms of time and space, so Distributed Frequent Itemset Mining (DFIM) algorithms have been designed to meet the above challenges. In this paper, LocalGlobal and RedistributionMining which are two main paradigms of DFIM algorithm are discussed; Two algorithms of these paradigms on MapReduce named LG and RM are proposed while MapReduce is a popular distributed computing model, and also the related work is discussed. The experimental results show that the RM algorithm has better performance in terms of computation and scalability of sites, and can be used as the basis for designing the DFIM algorithm based on MapReduce. This paper also discusses the main ideas of improving the DFIM algorithms based on MapReduce.     

Government ecological governance management based on heterogeneous multi-processors and dynamic image sampling

With the advent of the governance economy era, traditional government governance models face enormous challenges. Governance management is the source of power to enter the era of the knowledge economy. This is a profound change that governments have needed to implement innovative government governance models, methods of social organization, and management. Governments in many countries are now adopting the construction of e-government as a strategy and response to demonstrate their priority development competitive advantage over the international competition and the challenges of the knowledge economy that spreads around the world. Therefore, the establishment of a new model of government governance has great theoretical and practical significance for impulse and government management innovation. The Dynamic Image Classification Algorithm (DICA) system is introduced in the implementation of the image processing technology and global disaster detection proposed here, and of this dynamic image classification algorithm (DICA) of the government, sector to extract more effectively. DICA is the most important task, or it is a strong shadow, proper access to the characteristics of the disaster area, and a false impact on the impact of the disaster, overcoming false alarms. It creates patches of post-disaster aerial image data from pre-tailoring and pre-adjustment training and satellite imagery. DICA training, all patches to government-managed data modified without delay or image data extraction. Two types of proposed systems are high-speed operation and accuracy (96.6%) and detection of earth disasters.     

合成柠檬酸三丁酯的催化体系

柠檬酸三丁酯是一种新型无毒增塑剂.综述了磺酸、无机盐、固体超强酸、杂多酸、稀土化合物等催化体系对合成柠檬酸三丁酯的催化作用及研究进展.     

(-)-6,6-乙二氧撑-1,10-二甲基-1(9)-八氢萘酮-2的合成

乙基乙烯基酮与4,4-乙二氧撑-2-甲基环乙酮2 c的手性亚胺进行不对称Michael加成,生成2,2-双取代环烷酮5,5经过克莱森缩合得到(-)-6,6-乙二氧撑-1,10-二甲基-1(9)-八氢萘酮-2(-)(1 c)。     

白芍中芍药总苷的提取工艺研究

用正交实验法对白芍中芍药总苷的提取工艺进行优选,考察乙醇体积分数、固液比、提取时间对白芍中芍药总苷提取率的影响。结果表明,在浸提3次条件下,得到最佳工艺条件为:乙醇浓度85%,固液比为1∶5(g/mL),提取时间3 h。在此条件下,白芍中芍药总苷提取率为1.366%。     

新型台式电脑CPU供电电路分析

本文概括了CPU供电电路所采用的新技术,阐述了实现这些技术的VRM电路结构和工作原理,最后详细分析了一种新型X58M主板CPU供电电路的工作原理。     

基于事件的主动队列管理研究

针对随机早期检测RED存在的对参数过于敏感、时延抖动、队长不稳定等问题,采用特殊事件标记法,通过调整丢弃概率的增减幅度,对RED算法进行了改进。实验表明,改进的算法在稳定性、链路利用率方面有了较好的改善。