Electrochemical micromachining of nitinol by confined-etchant-layer technique

The confined etchant layer technique has been applied to fabricate complex three-dimensional microstructures on nitinol for the first time. HF and HNO₃ were locally and simultaneously electrogenerated at the mold surface to etch a nitinol workpiece. NaOH was used as an efficient scavenger to confine the etchant close to the mold. Cyclic voltammetry was employed to study the electrochemical behavior of a Pt electrode in the etching solution in order to choose an appropriate potential for etchant generation on the mold. The thickness of the confined etchant layer was estimated to be several micrometers by inspecting the deviation of the sizes of the etched spots from the sizes of those on the microelectrode. Thus, the composition of the electrolyte could be optimized for better etching precision. By optimizing the composition of the electrolyte, complex microstructures on a Pt-Ir mold bearing the logo “XMU” of Xiamen University were successfully fabricated on nitinol. The etched patterns were approximately negative copies of the mold, and the precision of duplication could easily reach the micrometer scale.     

货架喷塑前处理工艺的选择与应用

介绍了CZ99-03(7)常温锌系磷化剂在货架上的应用,根据货架构件的特点,优化货架喷塑前处理工艺,讨论了影响磷化质量的工艺因素,提出了提高磷化效果的措施以及进一步改进磷化工艺的工艺设计。     

水蓄冷运行控制分析

随着空调蓄冷技术的不断发展,它已逐渐在节能效果、经济效益和社会效益等方面展现出强大的生命力和广阔的市场。主要探讨了自然分层蓄冷形式,该方式利用温度和密度不同的原理,通过斜温层分隔高、低温水。必须严格进行水蓄冷系统的运行控制,否则极易打破其自然分层的规律。     

探索行动导向教学法在网络架构课程教学改革中的应用

技工学校是以技术型人才培养为目的的学生能力养成和技能操作的教育基地,为确保人才培养质量,学校需要加强对市场形势的把握和教学改革的控制。行动导向教学法是目前广泛应用于技校和职校教学课堂的、有较好实际作用的教学方法,文章以行动导向教学法为重点,以配置交换机实现VLAN学习任务为案例,在教学方法和手段等几个方面讨论了行动导向教学法在网络架构课程教学改革中的研究与实践。     

乳液聚合中单体醋酸乙烯酯与保护胶体聚乙烯醇的接枝反应研究

研究了以聚乙烯醇为保护胶体的醋酸乙烯乳液聚合中,聚乙烯醇与单体的接枝反应。探讨了引发剂用量、聚合反应温度、保护胶体聚合度等因素对接枝反应的影响。     

下期要目

在电气自动控制的设计过程中，设计者根据生产工艺要求和生产控制过程用经验设计法设计出来的控制电路，虽然通过了试验和一定时间的实践验证。但是随着时间的推移，其存在的隐性危害便会逐渐暴露出来，电气自动控制中寄生回路的存在及其隐性危害便是一例。     

入侵检测技术在消防信息网安全中的应用

消防信息网作为公安网子网,与互联网物理分隔,网络安全相对薄弱,自身的安全防护能力并不高。非法入侵、病毒破坏屡有发生,给消防信息网带来不可预测的后果。     

The onset of Taylor-Görtler vortices in impulsively decelerating swirl flow

The onset of hydrodynamical instability induced by impulsive spin-down to rest in a cylinder containing a Newtonian fluid is analyzed by using propagation theory. It is well-known that the primary transient swirl flow is laminar, but with initial high velocities secondary motion sets in at a certain time. The dimensionless critical time Τ_c to mark the onset of instability is presented here as a function of the Reynolds number Re. Available experimental data indicate that for large Re deviation of the velocity profiles from their momentum diffusion occurs starting from a certain time Τ≈4Τ_c. This means that secondary motion is detected at this characteristic time. It seems evident that during Τ_c⪯Τ⪯4Τ_c, secondary motion is relatively very weak and the primary diffusive momentum transfer is dominant.