Extended-state-observer-based output feedback adaptive control of hydraulic system with continuous friction compensation

This paper presents an extended state observer-based output feedback adaptive controller with a continuous LuGre friction compensation for a hydraulic servo control system. A continuous approximation of the LuGre friction model is employed, which preserves the main physical characteristics of the original model without increasing the complexity of the system stability analysis. By this way, continuous friction compensation is used to eliminate the majority of nonlinear dynamics in hydraulic servo system. Besides, with the development of a new parameter adaption law, the problems of parametric uncertainties are overcome so that more accurate friction compensation is realized. For another, the developed adaption law is driven by tracking errors and observation errors simultaneously. Thus, the burden of extended state observer to solve the remaining uncertainties is alleviated greatly and high gain feedback is avoided, which means better tracking performance and robustness are achieved. The designed controller handles not only matched uncertainties but also unmatched dynamics with requiring little system information, more importantly, it is based on output feedback method, in other words, the synthesized controller only relies on input signal and position output signal of the system, which greatly reduces the effects caused by signal pollution, measurement noise and other unexpected dynamics. Lyapunov-based analysis has proved this strategy presents a prescribed tracking transient performance and final tracking accuracy while obtaining asymptotic tracking performance in the presence of parametric uncertainties only. Finally, comparative experiments are conducted on a hydraulic servo platform to verify the high tracking performance of the proposed control strategy.     

一个工程系的创办和ABET评估认证:东卡罗来纳大学案例分享

从受评方的角度,总结了创办一个工程系和准备美国ABET工程技术专业认证的整个过程.首先对ABET和东卡罗来纳大学工程系进行必要的介绍,然后完整讲述了为准备ABET认证的组织协调,人员配置,评估计划书的制定,受评方与ABET的沟通,以及评估小组进校考察的前后过程.并且提供了课程-产出映射关系的具体实例.希望为中国工程教育同行今后准备此类认证工作提供实用的参考.     

Impacts of Globalization on E-Commerce Use and Firm Performance: A Cross-Country Investigation

This article develops and tests a model examining the relationship between firm globalization, scope of e-commerce use, and firm performance, using data from a large-scale cross-country survey of firms from three industries. We find that globalization leads to both greater scope of e-commerce use and improved performance, measured as efficiency, coordination, and market impacts. Scope of e-commerce use also leads to greater firm performance of all three types. Globalization has differential effects on B2B and B2C e-commerce, however, such that highly global firms are more likely to do B2B but less likely to do B2C. Our findings provide support for Porter's (1986) thesis that upstream business activities (namely, B2B) are more global while downstream business activities (B2C) are more local or multidomestic.     

Digital redesign tracker for cascaded analog systems with state saturation and external loads

This paper presents a newly developed digital redesign control scheme with a weighted switching strategy and output-reference tracking, for a cascaded analog system with state saturation and external loads. The proposed method improves the generally poor transition response and output deviation caused by state-saturation constraint and external loads. It replaces an existing or theoretically well-designed analog controller with state saturation, by a digital controller with almost identical performance.     

Understanding value in the student experience through student–staff partnerships

ABSTRACT

Questions such as ‘what is value in the student experience?’ and ‘how do we measure or assess value in higher education?’ remain an under-researched area. However, in the context of marketisation and competitive forces in higher education, there is a need to unpack what is value in the student experience. In this article, a conceptualisation of value that can be applied in higher education (known as value-in-use) is introduced and applied to a specific and increasingly important aspect of the student experience – student–staff partnerships. Qualitative survey data (n?=?97) and interviews (n?=?35) from ten cases of various manifestations of student–staff partnerships in the Australasian context is presented and assessed in relation to value. The findings highlight that student–staff partnerships may enhance value in the student experience and that value-in-use may be an appropriate lens through which to continue to explore how value is created and measured in the student experience.     

Recruiting the graduate voice: informing higher education initiatives to underpin an emerging,veterinary paraprofession in Australia

In Australia, the inception of veterinary technology, as a higher education discipline underpinning an emerging, mid-tier paraveterinary field, reflected global trends for more highly educated veterinary paraprofessionals to meet changing societal demands. In this study, veterinary technology graduates were surveyed about their experiences in the workforce and reflections on their education. Seeking feedback on how well a new programme has prepared graduates for the workforce is a useful quality assurance tool. Clinical veterinary practice was the primary employment sector with the majority of respondents in full-time employment. Career advancement, professional recognition and salaries were identified as key career challenges. The important roles of the veterinary and veterinary nursing professions, the university, government and graduates in the development of this mid-tier, veterinary paraprofession were elucidated. Graduates’ feedback on criteria that underpinned ‘work-readiness’ revealed seven key domains: communication skills, research skills, knowledge, critical thinking/problem-solving, employability, practical skills and professionalism. Veterinary nursing skills, work placement, practice management and production animal health were flagged as areas for curricular improvement. This study illuminated facilitators and barriers critical to establishing a mid-tier veterinary paraprofession, bridging the divide between the vocational and higher education sectors in Australia.

Abbreviations: AUD: Australian dollar; AVA: Australian Veterinary Association; AVBC: Australasian Veterinary Boards Council; AVMA: American Veterinary Medical Association; BVNA: British Veterinary Nursing Association; CSU: Charles Sturt University; DAF: Department of Agriculture and Fisheries; FWC: Fair Work Commission; GCA: Graduate Careers Australia; HE: Higher Education; NHMRC: National Health and Medical Research Council; QLD: Queensland; RCVS: Royal College of Veterinary Surgeons; UK: United Kingdom; UQ: University of Queensland; VN: Veterinary nursing; VNCA: Veterinary Nurses Council of Australia; VSB: Veterinary Surgeons Board; VT: Veterinary technology; WIL: Work-integrated learning.     

Phonological processing and emergent literacy in younger and older preschool children

Phonological awareness, phonological memory, and phonological access to lexical storage play important roles in acquiring literacy. We examined the convergent, discriminant, and predictive validity of these phonological processing abilities (PPA) in 389 3-, 4-, and 5-year-old children. Confirmatory factor analysis supported the validity of each PPA as separate from general cognitive ability and separate from each other. Multigroup structural equation modeling (SEM) with mean structure demonstrated that older preschoolers have better developed latent PPA than younger preschoolers but that the structure of PPA is equivalent. RAN was found uniquely associated with letter knowledge and text discrimination in younger preschoolers, and PA was found uniquely associated with word reading skills in older preschoolers. Finally, general cognitive ability was only indirectly associated with emergent literacy via PPA. These results highlight the importance of PPA in the early literacy development of English-speaking preschool children.     

The WISC-R and Woodcock-Johnson tests of cognitive ability: A comparative study

The Woodcock-Johnson Psycho-Educational Battery has become a popular instrument for assessing students with learning problems. Previous research has indicated a possible discrepancy between overall scores on the WISC-R and the congnitive portion of the Woodcock-Johnson with samples of learning disabled (LD) students. The current study, conducted with samples of students not designated as LD, also found significant differences in the mean scores between the two measures. The hypothesis that the difference between measures is a function of grade level was not supported. Other findings of the current study, coupled with previous research, suggest that the congnitive portion of the Woodcock-Johnson may be loaded with verbal factors.