基于纳米压入技术的新型MEMS/NEMS材料力学行为表征

准确了解微/纳米特征尺度条件下材料的力学性能是MEMS/NEMS(micro/nano electro-mechanical system)材料实际应用的一个关键前提条件.文中研究基于纳米压入技术的新型MEMS/NEMS材料力学行为的表征方法,包括高聚物、一维结构纳米材料和形状记忆合金等.研究结果表明,纳米压人技术是评定这些新型MEMS/NEMS材料力学性能的有力工具,并可作为有效的实验手段,揭示力学行为与其依存诸因素之间的内在关联.     

获取固定管板换热器管板一次弯曲应力的一种方法及其应用

利用载荷分解施加,提出一种构建固定管板换热器管板一次结构、获取一次弯曲应力的方法,一次结构中可保留简体对管板转动的有利多余约束.以一台甲醇合成塔为例,结合非一次结构法设计存在的问题,利用所提出的方法进行了有限元设计计算.计算表明,该方法给出的许用载荷与极限载荷分析法给出的许用载荷相当,方法可行.值得注意的是,如果应力评...     

纤维复合材料的可靠性优化研究

采用遗传算法分析有初始缺陷的层合板的可靠性优化问题.初始缺陷、强度参数为随机变量,采用一阶矩法分析单元层的可靠性,每个单层板考虑基体破坏和纤维断裂两种失效模式,系统失效概率的计算基于最终层失效理论.以纤维方向角和层合板厚度为设计变量,系统可靠度最小为目标,采用遗传算法计算优化问题.数值算例说明方法的有效性,分析不同失效理论时的最优解.     

电子鼻技术的发展及展望

文章介绍了电子鼻的定义、系统组成和工作原理,重点阐述了气敏传感器、信号与处理、模式识别等关键技术的发展现状;详细介绍了它在食品工业、精细化工、医疗诊断、环境监测、公安与海关、火星生命探索等方面的应用实例;最后展望了其未来发展趋势。     

烟花爆竹用有色火焰药剂燃放有害气体产物研究

文章通过最小自由能法理论计算和模拟实验研究,选取典型烟花爆竹产品中较为常用的红、绿、蓝、黄焰色药剂为研究对象,对烟花爆竹用有色火焰药剂燃放时的有害气体产物开展了研究。结果表明:有色火焰药剂燃放产物中的有害气体产物主要为CO,有色火焰药剂配方的负氧平衡是其燃放产物中有CO生成的主要原因,提高配方氧平衡可减少CO的生成。     

Corrosion and irradiation behavior of Fe-based amorphous coating in lead-bismuth eutectic liquids

Lead-bismuth eutectics (LBE) have considerable potential as a candidate material for accelerator-driven sub-critical systems (ADS). However, LBE corrosion and irradiation damage are two urgent challenges remaining to be solved for impellers of primary pumps. In this study, we have explored the possibility of using Fe-based amorphous coatings to overcome LBE corrosion and concurrently to sustain irradiation damage. Specifically, the Fe₅₄Cr₁₈Mo₂Zr₈B₁₈ amorphous coating was prepared by high-velocity oxygen-fuel (HVOF) spraying on 316L steel and exposed to saturated oxygen static LBE for 500 h at 400°C. The coating with high thermal stability (T_g=615°C and T_x=660°C) effectively prevented the substrate steel from being corroded by LBE owing to its unique long-range disordered atomic packing. The coating also exhibited strong irradiation resistance when being subjected to 45 dpa (displacement per atom) Au ion irradiation at room temperature, with no sign of crystallization even at the maximum implantation depth of 300 nm. Consequently, the hardness of the coatings before and after irradiation increased slightly. The current findings shed new insights into understanding corrosion mechanism and irradiation behavior of amorphous solids in LBE and expand the application range of amorphous materials.

     

一类自适应隐写的更改比率估计

针对图像自适应隐写的检测问题,分析了最低多有效位(MLSB,multiple least signific ant bits)替换隐写的样本对分析模型在对自适应隐写的适用性,给出了适于该模型检测的自适应隐写须满足的条件,对满足条件的一类自适应隐写,给出了基于特定区域和像素对分析的定量分析一般方法,然后针对一种典型自适应隐写,给出了具体的特定区域选取方法、样本对跟踪集选取方法和隐写更改比率估计算法.实验结果表明针对这种隐写,该算法能够较为准确地估计隐写更改比率,验证了文中方法的有效性.     

提高服务质量的信元丢弃算法

本文提出充分考虑各虚电路连接与拥塞发生处网络节点的信元所耗费的网络资源的不同而有选择地丢弃信元的算法,并描述了该算法的特性。基于该算法,会有更高的网络资源利用率和网络性能,而网络资源利用率的提高又可改善CLR和时延等指标。     

Operational-space wrench and acceleration capability analysis for multi-link cable-driven robots

Science China Technological Sciences - Multi-link cable-driven robots (MCDRs) have potential advantages in confined spaces exploration because of their redundancy and flexibility. Operational space...     

Enhancing interaction performance of soft pneumatic-networks grippers by skeleton topology optimization

Science China Technological Sciences - The inherent compliance of soft materials imbues robots, generally referred to as soft robots, with particular advantages in producing adaptive and safe...