Stress dependent properties of Ga-doped ZnO thin films prepared by magnetron sputtering

Ga doped ZnO films have been prepared by radio frequency magnetron sputtering at room temperature. The (002) preferential orientation is observed for all the films. In plane lattice parameters of the films are obtained by X-ray diffraction θ–2θ scan with the samples tilted 61.63°. Intrinsic compressive stress is observed parallel to the film surface, varying from 410 to 3,000 MPa. Electrical properties of the films show a great dependence on the stress. Carrier concentration and mobility are both improved as the intrinsic compressive stress is reduced which is greatly affected by adjusting the deposition pressure. Therefore, the electrical resistivity is optimized to be 1.8 × 10^?3 Ω·cm for the film prepared at 8.0 Pa. In addition, the optical analysis reveals that the transmittance of the films is higher than 90 %. The band gap of the films increases from 3.11 to 3.38 eV with decreasing the stress due to the increase in the carrier concentration, which is related to Burstein–Moss effect.     

Generating collision-free tool orientations for 5-axis NC machining with a short ball-end cutter

A novel tool orientation optimisation algorithm is proposed for 5-axis NC machining with a short ball-end cutter. It can generate collision-free and smooth tool orientations along with a safe and shortest tool length (SSTL). The use of shorter cutters without collision is a key advantage of 5-axis machining because the magnitude of tool deflection and the stability of cutting process are greatly affected by the slenderness ratio of the cutter. Existing methods can calculate the SSTL in the NC simulation process. However, the SSTL is essentially determined by the tool orientations and should be considered in the process of tool path generation. To overcome this limitation, a new tool orientation optimisation algorithm is proposed. The SSTL is determined by optimising the tool orientations under the constraints of global collision avoidance and tool orientation smoothness. The algorithm first computes the global accessibility cone and the SSTL along each accessible tool orientation. Then the tool orientations are optimised based on the discrete dynamic programming with the SSTL along the whole tool path being the optimisation objective. Finally, the tool path is generated by globally smoothing the tool orientations. Computational examples and cutting experiment are given to illustrate the validity and efficiency of the proposed algorithm.     

Asymmetric polyurethane membrane with inflammation-responsive antibacterial activity for potential wound dressing application

By combining solvent evaporation with wet phase inversion technique, an asymmetric polyurethane membrane (ASPU) was constructed from a sulfanilamide-conjugated PU, as a potential candidate for wound dressing application. As a result of the combined membrane-formation method, the ASPU membrane was constituted by an integral and dense skin layer supported by a porous sublayer. The skin layer was found impermeable to pathogenic organisms, while the sublayer was intended for draining excessive exudates. Compared with typical PU membrane dressings commercially available, the ASPU membrane exhibited a reasonable moisture vapor transmission rate, as well as significantly improved gas circulation and exudate absorption capabilities, which synergistically optimized the wound microenvironment for proper healing. Furthermore, the sulfanilamide-conjugated PU constituting ASPU membrane was designed as susceptible to urease, a representative hydrolase derived from inflammation-causing pathogens. In the presence of urease, urea linkages adjacent to sulfanilamide monomeric units were found catalytically cleaved, enabling release of free antibiotic sulfanilamide that held pharmacological activity from ASPU membrane. When incubated without urease, those cleavage sites exhibited substantially high resistance against hydrolysis so that no sulfanilamide release was detected throughout the incubation period. In this inflammation-responsive manner, the anti-inflammatory efficiency of antibiotics was significantly enhanced, while undesirable side effects associated with antibiotic abuse was minimized. Cell culture assay further revealed that the ASPU membrane displayed no cytotoxicity toward normal human dermis fibroblasts, suggesting a biocompatible potential. Based on these results, the multifunctional ASPU membrane designed in this study might be clinically suitable as an ideal biomedical dressing for wound care.     

A generic Petri net model for flexible manufacturing systems and its use for FMS control software testing

Developing a flexible manufacturing system (FMS) controller is a complicated task both in the hardware development and software development. To test the control software prior to putting it into use is crucial for the development of a FMS controller. An intelligent testing environment for FMS controllers is under development, the aim of which is to reduce manual work in the testing. To reach this objective the automatic building of a behavioural model of the FMS is demanded. This paper proposes a generic Petri net (GPN) model and approach for the development of control software for FMSs. The principle of this approach is based on checking the control parts of FMSs with the help of temporal relationships between physical operations, and the specification of the FMS controller with GPN. The strategy of GPN modelling is then incorporated with more general problem solving strategies in artificial intelligence. A template is first defined for a GPN model, and then the model for FMS individuals is established in the form of instances of the template. The transitions of the GPN are represented with the proposed general expressions with two syntaxes, 'verb+ noun' and 'verb+ noun+ where', from which the GPN can be formulated. GPN makes it simple to express FMS controls, and procedural language can also be used for information processing. A case study for the testing of FMS controller software is provided to show effectiveness and cost saving over development with conventional methods in which only ordinary Petri net and procedural language are used.     

中高职护生职业指导现况分析

目的了解中高职护生职业指导现状,探讨中高职护生职业指导模式。方法针对目前中高职护生职业指导现状及存在的问题,对职业指导进行探讨。结果提出中高职护生职业指导模式的建议,改革和完善中高职护生职业指导现状。结论学校应针对中高职护生全面开展专业的职业指导,从而提高中高职护生就业质量。     

矿用胶带输送机液压纠偏装置的研究与应用

分析了胶带输送机发生胶带跑偏的原因,并对胶带跑偏现象进行了力学分析,对比了目前常见的几种纠偏装置的优缺点,设计了液压纠偏装置,对该装置的纠偏工作原理及优点进行了介绍。该装置在南屯煤矿使用后,减少了因胶带跑偏而造成的各种危害和事故,保障了矿井煤流系统的安全运转。     

一次成井技术在石人沟铁矿的应用

传统上分段凿岩阶段矿房法切割天井的形成,大都采用7655型凿岩机进行浅孔凿岩方式,人员劳动强度大,劳动效率低,且安全上也没有保障,为提高劳动效率,石人沟铁矿采用进口1254台车,进行中深孔凿岩,一次爆破成井,大幅提高了劳动效率,降低了人员劳动强度,提高了安全系数.     

基于Labview的激光光热法界面热阻测量系统

根据激光光热法原理,设计了一套低温下界面热阻测量系统,通过Labview操作平台实现对实验温度的精确控制以及对实验数据的自动采集记录。该实验系统能够实现低温下超导带材与导冷材料间界面热阻的测量,为研究直接冷却条件下超导磁体的应用提供实验依据。     

Nd:YAG透明陶瓷的研究进展

掺钕钇铝石榴石(Nd:Y3Al5O12,Nd:YAG)多晶陶瓷具有易制造、成本低、尺寸大、掺杂原子分数高、热导率高、耐热冲击性好、可大批量生产、易实现多层和多功能的陶瓷结构等优点,是目前应用范围最广的固体激光材料。综述了近年来国内外关于YAG激光透明陶瓷的最新研究成果,展望了陶瓷激光器的未来发展价值。