Modelling and joint monitoring of input and output of systems with arbitrary order autoregressive disturbance

Considerable studies have been done on modelling and joint monitoring of input and output of systems with autoregressive moving average (ARMA) disturbance. Most of these studies focus on systems with ARMA (1, 1) disturbance. However, many kinds of systems are not conform to ARMA(1, 1) disturbance. Motivated by the fact that an autoregressive (AR) model with high order can be implemented to approximate the stationary ARMA model at any precision, a new generic model and a joint monitoring scheme of systems with arbitrary order AR(p) disturbance are developed. A minimum mean squared error (MMSE) controller with arbitrary order AR disturbance is designed to reduce the system variability. The mathematical expectation and average run length of MMSE-controlled outputs are derived. A new joint chart for monitoring the input and output simultaneously is explored. Two out-of-control rules for the joint monitoring chart are developed. The monitoring performances of the input chart, the output chart and the joint monitoring chart are also discussed. The results of simulation experiments and case studies validate the effectiveness of the developed model and joint monitoring chart.     

Effects of microstructural heterogeneity on very high cycle fatigue properties of 7050-T7451 aluminum alloy friction stir butt welds

In this study, the very high cycle fatigue (VHCF) properties of 7050-T7451 aluminum alloy and its friction stir welding (FSW) butt welds have been investigated. The results show that the failure of FSW joints still occurs at 7.0 × 10⁸ cycles. The fatigue properties of the FSW joints are superior to those of the base material, especially in the super long life regime. Most fatigue cracks initiate at the thermo-mechanically affected zone and heat affected zone on the advancing side of the FSW joints, and the susceptibility of these zones to fatigue is attributed to the metallurgical heterogeneity.     

Engineered microparticles based on drug–polymer coprecipitates for ocular-controlled delivery of Ciprofloxacin: influence of technological parameters

Abstract

Ciprofloxacin is a drug active against a broad spectrum of aerobic Gram-positive and Gram-negative bacteria, for the therapy of ocular infections. It requires frequent administrations owing to rapid ocular clearance and it is a good candidate for ocular controlled release formulations. The preparation of such drug release systems is still a challenge. Ionic interactions between ciprofloxacin and the polyelectrolytes chondroitin sulfate or lambda carrageenan result in coprecipitates that can act as microparticulate controlled release systems from which the drug is released after being displaced by the medium’s ions. In some formulations, Carbopol was added to improve the mucoadhesive properties. The aim of this research was the study of the influence of the technological parameters of the preparation method of coprecipitates on their particle size, with the goal of achieving particles engineered with a size suitable for the ocular administration. Technological parameters taken into account were: concentration of drug and polymer solutions utilized for the preparation of interaction products, possible use of surfactants (kind and concentration), temperature of the solutions and stirring during the process of preparation of the coprecipitates. Preliminary stability study tests were carried out to further characterize the leader formulation. Particle size in suspensions for ocular drug delivery is a critical parameter influencing the quality of the formulation. The results obtained from this study show that chondroitin sulfate coprecipitates present the best characteristics in terms of particle size suitable for ocular administration. A further improvement of the particle size characteristics has been obtained with the addition of surfactants.     

Al-20Cu-9.6Si-xEr钎料对SiC_p/A356复合材料真空钎焊接头组织与性能的影响EI北大核心CSCD

采用不同铒含量的7组Al-20Cu-9.6Si-xEr钎料分别对SiCp/A356复合材料进行了真空钎焊。利用扫描电镜和能谱分析等方法对接头微观组织进行了观察和分析。通过剪切实验对钎焊接头的抗剪强度进行了测定,并对剪切断口的微观形貌进行了观察。结果表明：添加稀土后,钎焊接头的抗剪强度明显提高。当w（Er）=0%时,钎缝处SiC颗粒聚集严重,接头强度为43.5MPa;当w（Er）=0.05%时,钎缝边界无SiC颗粒的聚集,接头强度最高,达到68.6MPa;当w（Er）=0.1%-0.4%时,钎缝处SiC颗粒聚集趋势减弱,接头强度值在45.3-50.5MPa之间;当w（Er）=0.5%时,SiC颗粒分布在钎缝内部,接头强度明显提高,达到62.2MPa。     

激光热处理对1Cr5Mo钢焊接接头组织结构的影响

利用CO_2激光对1Cr5Mo耐热钢焊接接头进行表面热处理,通过4XC型光学显微镜对激光热处理前后焊接接头各区显微组织和晶粒度等级进行分析,并采用X射线应力仪测定激光热处理前后焊接接头残余应力和残余奥氏体的分布规律。结果表明:经激光热处理后1Cr5Mo耐热钢焊接接头表面晶粒发生细化,焊缝区、熔合区、过热区和正火区晶粒等级由9级、9.8级、8级和10.7级提升至10级、10.2级、8.5级和11级,组织结构薄弱区域由过热区、焊缝区和熔合区减少为过热区,均匀性得到了明显改善;激光热处理消除了焊接接头表面残余拉应力,形成了深度约为0.28mm的残余压应力层,残余奥氏体含量有所提高,分布更均匀,有利于改善其力学性能。     

船用5083铝合金厚板搅拌摩擦焊接工艺研究

研究了30 mm厚铝合金5083板材双面对接焊不同焊接速度和旋转速度的焊接参数组合对焊接接头成型质量及力学性能的影响,结果表明,当焊接参数处于旋转速度为400 r/min~600 r/min,焊接速度为80mm/min~120 mm/min的工艺参数窗口内时,可以获得焊缝成型质量与抗拉性能优异的焊缝。     

The privileged sensing framework: A principled approach to improved human-autonomy integration

ABSTRACT

A primary goal for human-autonomy integration (HAI) is to balance the strengths of human and autonomy in order to achieve performance objectives more efficiently and robustly than either the human or autonomous agents would independently. This paper proposes the Privileged Sensing Framework (PSF) as a novel approach to HAI. This approach is based on the concept of dynamically ‘privileging’ information during the process of integration by dynamically bestowing special rights based on the characteristics of each individual agent, the task context, and the performance goals. The proposed framework is tested through a series of simulation experiments that provide a clear demonstration of increased accuracy and throughput of human-autonomy performance. These proof-of-concept simulations provide initial evidence of the utility of the PSF. Continued development of this approach has the potential to revolutionise capabilities of multi-agent cooperative teams across a broad range of applications.     

旋转状态下微波叶尖间隙传感器校准影响因素分析

主要针对应用于发动机叶尖间隙测量的微波叶尖间隙传感器的校准需求,对测量原理、传感器的校准原理等进行了详细阐述,并分析了转速和回缩值等对校准结果的影响。为微波叶尖间隙传感器的进一步优化设计及应用提供了数据依据。     

考虑通关水平的跨境物流服务供应链契约协调机制研究

为实现跨境物流服务供应链完全协调,运用Stackelberg博弈理论,构建由一个跨境物流服务供应商与一个物流服务集成商组成的二级供应链。采用因子分析法测度通关水平,分析通关水平对跨境物流服务供应链最优决策及协调运作的影响,设计可供跨境物流服务供应链完美协调的契约机制。研究表明,考虑通关水平使跨境物流服务供应链成员及供应链整体利润均得到提升;集中决策下跨境物流服务供应链整体利润总是高于分散决策;收益共享契约可实现跨境物流服务供应商及供应链整体决策的帕累托优化,但不能达到供应链的完全协调,而Nash协商改进的二部定价契约模型可实现供应链的完全协调。